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Sample records for spectral radiometric spatial

  1. The effect of spatial, spectral and radiometric factors on classification accuracy using thematic mapper data

    NASA Technical Reports Server (NTRS)

    Wrigley, R. C.; Acevedo, W.; Alexander, D.; Buis, J.; Card, D.

    1984-01-01

    An experiment of a factorial design was conducted to test the effects on classification accuracy of land cover types due to the improved spatial, spectral and radiometric characteristics of the Thematic Mapper (TM) in comparison to the Multispectral Scanner (MSS). High altitude aircraft scanner data from the Airborne Thematic Mapper instrument was acquired over central California in August, 1983 and used to simulate Thematic Mapper data as well as all combinations of the three characteristics for eight data sets in all. Results for the training sites (field center pixels) showed better classification accuracies for MSS spatial resolution, TM spectral bands and TM radiometry in order of importance.

  2. Evaluation of spatial, radiometric and spectral Thematic Mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V.; Ackleson, S. G.; Hardisky, M. A.

    1985-01-01

    On 31 March 1983, the University of Delaware's Center for Remote Sensing initiated a study to evaluate the spatial, radiometric and spectral performance of the LANDSAT Thematic Mapper for coastal and estuarine studies. The investigation was supported by Contract NAS5-27580 from the NASA Goddard Space Flight Center. The research was divided into three major subprojects: (1) a comparison of LANDSAT TM to MSS imagery for detecting submerged aquatic vegetation in Chesapeake Bay; (2) remote sensing of submerged aquatic vegetation - a radiative transfer approach; and (3) remote sensing of coastal wetland biomass using Thematic Mapper wavebands.

  3. Investigation of LANDSAT follow-on thematic mapper spatial, radiometric and spectral resolution

    NASA Technical Reports Server (NTRS)

    Nalepka, R. F. (Principal Investigator); Morgenstern, J. P.; Kent, E. R.; Erickson, J. D.

    1976-01-01

    The author has identified the following significant results. Fine resolution M7 multispectral scanner data collected during the Corn Blight Watch Experiment in 1971 served as the basis for this study. Different locations and times of year were studied. Definite improvement using 30-40 meter spatial resolution over present LANDSAT 1 resolution and over 50-60 meter resolution was observed, using crop area mensuration as the measure. Simulation studies carried out to extrapolate the empirical results to a range of field size distributions confirmed this effect, showing the improvement to be most pronounced for field sizes of 1-4 hectares. Radiometric sensitivity study showed significant degradation of crop classification accuracy immediately upon relaxation from the nominally specified values of 0.5% noise equivalent reflectance. This was especially the case for data which were spectrally similar such as that collected early in the growing season and also when attempting to accomplish crop stress detection.

  4. Radiometric and Spectral Measurement Instruments

    DTIC Science & Technology

    1992-03-18

    NSWCCR/RDTN-92/0003 AD-A250 771LI~ llliii11l li l l iillt111 RADIOMETRIC AND SPECTRAL MEASUREMENT INSTRUMENTS CRANE DIVISION NAVAL SURFACE WARFARE... INSTRUMENTS 6. AUTHOR(S) B. E. DOUDA H. A. WEBSTER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) a. PERFORMING ORGANIZATION REPORT NIJMBER...Maxiry-um 200 w ords) THIS IS A DESCRIPTION OF AN ASSORTMENT OF RADIOMETRIC AND SPECTRAL INSTRUMENTATION USED FOR MEASUREMENT OF THE RADIATIVE OUTPUT OF

  5. The Moon Mineralogy (M3) Imaging Spectrometer: Early Assessment of the Spectral, Radiometric, Spatial and Uniformity Properties

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Pieters, C. M.; Boardman, J.; Barr, D.; Bruce, C.; Bousman, J.; Chatterjee, A.; Eastwood, M.; Essandoh, V.; Geier, S.; Glavich, T.; Green, R.; Haemmerle, V.; Hyman, S.; Hovland, L.; Koch, T.; Lee, K.; Lundeen, S.; Motts, E.; Mouroulis, P.; Paulson, S.; Plourde, K.; Racho, C.; Robinson, D.; Rodriquez, J.

    2009-01-01

    The Moon Mineralogy Mapper's (M3) is a high uniformity and high signal-to-noise ratio NASA imaging spectrometer that is a guest instrument on the Indian Chandrayaan-1 Mission to the Moon. The laboratory measured spectral, radiometric, spatial, and uniformity characteristics of the M3 instrument are given. The M3 imaging spectrometer takes advantage of a suite of critical enabling capabilities to achieve its measurement requirement with a mass of 8 kg, power usage of 15 W, and volume of 25X18X12 cm. The M3 detector and spectrometer are cooled by a multi-stage passive cooler. This paper presents early M3 performance assessment results.

  6. Evaluation of spatial, radiometric and spectral thematic mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V.

    1985-01-01

    The main emphasis of the research was to determine what effect different wetland plant canopies would have upon observed reflectance in Thematic Mapper bands. The three major vegetation canopy types (broadleaf, gramineous and leafless) produce unique spectral responses for a similar quantity of live biomass. Biomass estimates computed from spectral data were most similar to biomass estimates determined from harvest data when models developed for a specific canopy were used. In other words, the spectral biomass estimate of a broadleaf canopy was most similar to the harvest biomass estimate when a broadleaf canopy radiance model was used. Work is continuing to more precisely determine regression coefficients for each canopy type and to model the change in the coefficients with various combinations of canopy types. Researchers suspect that textural and spatial considerations can be used to identify canopy types and improve biomass estimates from Thematic Mapper data.

  7. Evaluation of spatial, radiometric and spectral Thematic Mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1984-01-01

    The effect different wetland plant canopies have upon observed reflectance in Thematic Mapper bands is studied. The three major vegetation canopy types (broadleaf, gramineous and leafless) produce unique spectral responses for a similar quantity of live biomass. The spectral biomass estimate of a broadleaf canopy is most similar to the harvest biomass estimate when a broadleaf canopy radiance model is used. All major wetland vegetation species can be identified through TM imagery. Simple regression models are developed equating the vegetation index and the infrared index with biomass. The spectral radiance index largely agreed with harvest biomass estimates.

  8. Evaluation of spatial, radiometric and spectral Thematic Mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1983-01-01

    A series of experiments were initiated to determine the feasibility of using thematic mapper spectral data to estimate wetlands biomass. The experiments were conducted using hand-held radiometers simulating thematic mapper wavebands 3, 4 and 5. Spectral radiance data were collected from the ground and from a low altitude aircraft in an attempt to gain some insight into the potential utility of actual thematic mapper data for biomass estimation in wetland plant communities. In addition, radiative transfer models describing volume reflectance of eight water column containing submerged aquatic vegetation were refined.

  9. Evaluation of spatial, radiometric and spectral Thematic Mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1984-01-01

    The effect different wetland plant canopies have upon observed reflectance in Thematic Mapper bands is examined. The three major vegetation canopy types (broadleaf, gramineous and leafless) produce unique spectral responses for a similar quantity of live biomass. Biomass estimates computed from spectral data were most similar to biomass estimates determined from harvest data when models developed for a specific canopy were used. Precise determination of regression coefficients for each canopy type and modeling changes in the coefficients with various combinations of canopy types are being tested. The multispectral band scanner vegetation index estimates are very similar to the vegetation index estimates.

  10. Evaluation of spatial, radiometric and spectral thematic mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V. (Principal Investigator)

    1983-01-01

    An area along the southeastern shore of the Chesapeake Bay was subsetted from TM imagery. The subsetted image was then enhanced and classified using an ERDAS 400 system. Results obtained were compared with a chart showing the distribution of both Zolsters marina and Rupplia martime in the Vaucluse Shores and which supports a large community of SAV. Radiative transfer models describing the irradiance reflectance of a water column containing SAV are being refined. Radiative transfer theory was used to model upwelling radiance for an orbiting sensor viewing an estuarine environment. Upwelling radiance was calculated for a clear maritime atmosphere, an optically shallow estuary of either clear or turbid water, and one of three bottom types: vegetation, sand, or mud using TM bands 1, 2, and 3 and MSS bands 4 and 5. A spectral quality index was defined similar to the equation for apparent contrast and used to evaluate the relative effectiveness of TM and MSS bands in detecting submerged vegetation.

  11. GIFTS SM EDU Radiometric and Spectral Calibrations

    NASA Technical Reports Server (NTRS)

    Tian, J.; Reisse, R. a.; Johnson, D. G.; Gazarik, J. J.

    2007-01-01

    The Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) Sensor Module (SM) Engineering Demonstration Unit (EDU) is a high resolution spectral imager designed to measure infrared (IR) radiance using a Fourier transform spectrometer (FTS). The GIFTS instrument gathers measurements across the long-wave IR (LWIR), short/mid-wave IR (SMWIR), and visible spectral bands. The raw interferogram measurements are radiometrically and spectrally calibrated to produce radiance spectra, which are further processed to obtain atmospheric profiles via retrieval algorithms. This paper describes the processing algorithms involved in the calibration. The calibration procedures can be subdivided into three categories: the pre-calibration stage, the calibration stage, and finally, the post-calibration stage. Detailed derivations for each stage are presented in this paper.

  12. Study of Spectral/Radiometric Characteristics of the Thematic Mapper for Land Use Applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A. (Principal Investigator); Metzler, M. D. (Principal Investigator)

    1985-01-01

    An investigation conducted in support of the LANDSAT 4/5 Image Data Quality Analysis (LIDQA) Program is discussed. Results of engineering analyses of radiometric, spatial, spectral, and geometric properties of the Thematic Mapper systems are summarized; major emphasis is placed on the radiometric analysis. Details of the analyses are presented in appendices, which contain three of the eight technical papers produced during this investigation; these three, together, describe the major activities and results of the investigation.

  13. Evaluation of computational radiometric and spectral sensor calibration techniques

    NASA Astrophysics Data System (ADS)

    Manakov, Alkhazur

    2016-04-01

    Radiometric and spectral calibration are essential for enabling the use of digital sensors for measurement purposes. Traditional optical calibration techniques require expensive equipment such as specialized light sources, monochromators, tunable filters, calibrated photo-diodes, etc. The trade-offs between computational and physics-based characterization schemes are, however, not well understood. In this paper we perform an analysis of existing computational calibration schemes and elucidate their weak points. We highlight the limitations by comparing against ground truth measurements performed in an optical characterization laboratory (EMVA 1288 standard). Based on our analysis, we present accurate and affordable methods for the radiometric and spectral calibration of a camera.

  14. Issues in Absolute Spectral Radiometric Calibration: Intercomparison of Eight Sources

    NASA Technical Reports Server (NTRS)

    Goetz, Alexander F. H.; Kindel, Bruce; Pilewskie, Peter

    1998-01-01

    The application of atmospheric models to AVIRIS and other spectral imaging data to derive surface reflectance requires that the sensor output be calibrated to absolute radiance. Uncertainties in absolute calibration are to be expected, and claims of 92% accuracy have been published. Measurements of accurate surface albedos and cloud absorption to be used in radiative balance calculations depend critically on knowing the absolute spectral-radiometric response of the sensor. The Earth Observing System project is implementing a rigorous program of absolute radiometric calibration for all optical sensors. Since a number of imaging instruments that provide output in terms of absolute radiance are calibrated at different sites, it is important to determine the errors that can be expected among calibration sites. Another question exists about the errors in the absolute knowledge of the exoatmospheric spectral solar irradiance.

  15. Spectrally and Radiometrically Stable, Wideband, Onboard Calibration Source

    NASA Technical Reports Server (NTRS)

    Coles, James B.; Richardson, Brandon S.; Eastwood, Michael L.; Sarture, Charles M.; Quetin, Gregory R.; Porter, Michael D.; Green, Robert O.; Nolte, Scott H.; Hernandez, Marco A.; Knoll, Linley A.

    2013-01-01

    The Onboard Calibration (OBC) source incorporates a medical/scientific-grade halogen source with a precisely designed fiber coupling system, and a fiber-based intensity-monitoring feedback loop that results in radiometric and spectral stabilities to within less than 0.3 percent over a 15-hour period. The airborne imaging spectrometer systems developed at the Jet Propulsion Laboratory incorporate OBC sources to provide auxiliary in-use system calibration data. The use of the OBC source will provide a significant increase in the quantitative accuracy, reliability, and resulting utility of the spectral data collected from current and future imaging spectrometer instruments.

  16. Radiometric flight results from the HyperSpectral Imager for Climate Science (HySICS)

    NASA Astrophysics Data System (ADS)

    Kopp, Greg; Smith, Paul; Belting, Chris; Castleman, Zach; Drake, Ginger; Espejo, Joey; Heuerman, Karl; Lanzi, James; Stuchlik, David

    2017-04-01

    Long-term monitoring of the Earth-reflected solar spectrum is necessary for discerning and attributing changes in climate. High radiometric accuracy enables such monitoring over decadal timescales with non-overlapping instruments, and high precision enables trend detection on shorter timescales. The HyperSpectral Imager for Climate Science (HySICS) is a visible and near-infrared spatial/spectral imaging spectrometer intended to ultimately achieve ˜ 0.2 % radiometric accuracies of Earth scenes from space, providing an order-of-magnitude improvement over existing space-based imagers. On-orbit calibrations from measurements of spectral solar irradiances acquired by direct views of the Sun enable radiometric calibrations with superior long-term stability than is currently possible with any manmade spaceflight light source or detector. Solar and lunar observations enable in-flight focal-plane array (FPA) flat-fielding and other instrument calibrations. The HySICS has demonstrated this solar cross-calibration technique for future spaceflight instrumentation via two high-altitude balloon flights. The second of these two flights acquired high-radiometric-accuracy measurements of the ground, clouds, the Earth's limb, and the Moon. Those results and the details of the uncertainty analyses of those flight data are described.

  17. Determination of in-flight AVIRIS spectral, radiometric, spatial and signal-to-noise characteristics using atmospheric and surface measurements from the vicinity of the rare-earth-bearing carbonatite at Mountain Pass, California

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Vane, Gregg; Conel, James E.

    1988-01-01

    An assessment of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) performance was made for a flight over Mountain Pass, California, July 30, 1987. The flight data were reduced to reflectance using an empirical algorithm which compensates for solar, atmospheric and instrument factors. AVIRIS data in conjunction with surface and atmospheric measurements acquired concurrently were used to develop an improved spectral calibration. An accurate in-flight radiometric calibration was also performed using the LOWTRAN 7 radiative transfer code together with measured surface reflectance and atmospheric optical depths. A direct comparison with coincident Thematic Mapper imagery of Mountain Pass was used to demonstrate the high spatial resolution and good geometric performance of AVIRIS. The in-flight instrument noise was independently determined with two methods which showed good agreement. A signal-to-noise ratio was calculated using data from a uniform playa. This ratio was scaled to the AVIRIS reference radiance model, which provided a basis for comparison with laboratory and other in-flight signal-to-noise determinations.

  18. IRCM spectral signature measurements instrumentation featuring enhanced radiometric accuracy

    NASA Astrophysics Data System (ADS)

    Lantagne, Stéphane; Prel, Florent; Moreau, Louis; Roy, Claude; Willers, Cornelius J.

    2015-10-01

    Hyperspectral Infrared (IR) signature measurements are performed in military applications including aircraft- and -naval vessel stealth characterization, detection/lock-on ranges, and flares efficiency characterization. Numerous military applications require high precision measurement of infrared signature characterization. For instance, Infrared Countermeasure (IRCM) systems and Infrared Counter-Countermeasure (IRCCM) system are continuously evolving. Infrared flares defeated IR guided seekers, IR flares became defeated by intelligent IR guided seekers and Jammers defeated the intelligent IR guided seekers [7]. A precise knowledge of the target infrared signature phenomenology is crucial for the development and improvement of countermeasure and counter-countermeasure systems and so precise quantification of the infrared energy emitted from the targets requires accurate spectral signature measurements. Errors in infrared characterization measurements can lead to weakness in the safety of the countermeasure system and errors in the determination of detection/lock-on range of an aircraft. The infrared signatures are analyzed, modeled, and simulated to provide a good understanding of the signature phenomenology to improve the IRCM and IRCCM technologies efficiency [7,8,9]. There is a growing need for infrared spectral signature measurement technology in order to further improve and validate infrared-based models and simulations. The addition of imagery to Spectroradiometers is improving the measurement capability of complex targets and scenes because all elements in the scene can now be measured simultaneously. However, the limited dynamic range of the Focal Plane Array (FPA) sensors used in these instruments confines the ranges of measurable radiance intensities. This ultimately affects the radiometric accuracy of these complex signatures. We will describe and demonstrate how the ABB hyperspectral imaging spectroradiometer features enhanced the radiometric accuracy

  19. Study of spectral/radiometric characteristics of the Thematic Mapper for land use applications: Objectives, accomplishments, conclusions, and recommendations

    NASA Technical Reports Server (NTRS)

    Malila, W. A.; Metzler, M. D.

    1985-01-01

    The objectives of this investigation are to quantify the performance of the Thematic Mapper, as manifested by the quality of its image data, in order to suggest improvements in data production and to assess the effects of the data quality on its utility for land resources applications. Analyses of radiometric, spatial, spectral, and geometric effects, with primary emphasis on radiometric effects are included. This effort is part of the LANDSAT 4/5 Image Data Quality Analysis (LIDQA) program sponsored by the NASA Goddard Space Flight Center.

  20. Simultaneous Inflight Spectral and Radiometric Calibration Validation of AVRIS and HYDICE Over Lunar Lake, Nevada

    NASA Technical Reports Server (NTRS)

    Chrien, Thomas; Green, Robert; Chovit, Chris; Faust, Jessica; Johnson, Howell; Basedow, Robert; Zalewski, Edward; Colwell, John

    1995-01-01

    An experiment to check the spectral and radiometric calibration of two sensors--the airborne visible/infrared imaging spectromenter (AVRIS) and the Hyperspectral digital image collection experiment (HYDICE)--is described.

  1. Performance and Results from a Space Borne, Uncooled Microbolometer Array Spectral Radiometric Imager

    NASA Technical Reports Server (NTRS)

    Spinhirne, James M; Scott, V. Stan; Lancaster, Redgie S.; Manizade, Kathrine; Palm, Steven P.

    2000-01-01

    The Infrared Spectral Imaging Radiometer experiment was flown on a space shuttle mission as a shuttle hitchhiker experiment in August of 1997. The goals of the experiment were to test uncooled array detectors for infrared spectral imaging from space and to apply for the first time retrieval from space of brightness temperatures of cloud, land and sea along with direct laser measurements of cloud top height. The instrument operates in 3 narrow and one broad spectral band, all between 7 and 13 microns in either stare or time-delay and integration mode. The nominal spatial resolution was 1/4 kilometer. Using onboard calibrations along with periodic views of deep space, radiometric calibration of imagery was carried out and performance analyzed. The noise equivalent temperature difference and absolute accuracy reported here varied with operating mode, spectral band and scene temperature but were within requirements. This paper provides a description of the instrument, its operating modes, the method of brightness temperature retrieval, the method of spectral registration and results from the flight.

  2. Spatial and radiometric characterization of multi-spectrum satellite images through multi-fractal analysis

    NASA Astrophysics Data System (ADS)

    Alonso, Carmelo; Tarquis, Ana M.; Zúñiga, Ignacio; Benito, Rosa M.

    2017-03-01

    Several studies have shown that vegetation indexes can be used to estimate root zone soil moisture. Earth surface images, obtained by high-resolution satellites, presently give a lot of information on these indexes, based on the data of several wavelengths. Because of the potential capacity for systematic observations at various scales, remote sensing technology extends the possible data archives from the present time to several decades back. Because of this advantage, enormous efforts have been made by researchers and application specialists to delineate vegetation indexes from local scale to global scale by applying remote sensing imagery. In this work, four band images have been considered, which are involved in these vegetation indexes, and were taken by satellites Ikonos-2 and Landsat-7 of the same geographic location, to study the effect of both spatial (pixel size) and radiometric (number of bits coding the image) resolution on these wavelength bands as well as two vegetation indexes: the Normalized Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI). In order to do so, a multi-fractal analysis of these multi-spectral images was applied in each of these bands and the two indexes derived. The results showed that spatial resolution has a similar scaling effect in the four bands, but radiometric resolution has a larger influence in blue and green bands than in red and near-infrared bands. The NDVI showed a higher sensitivity to the radiometric resolution than EVI. Both were equally affected by the spatial resolution. From both factors, the spatial resolution has a major impact in the multi-fractal spectrum for all the bands and the vegetation indexes. This information should be taken in to account when vegetation indexes based on different satellite sensors are obtained.

  3. Time-Series Hyperspectral and Multi-spectral Radiometric Measurements at the Martha's Vineyard Coastal Observatory

    NASA Astrophysics Data System (ADS)

    Lohrenz, S. E.; Sosik, H. M.; Crockford, E. T.; Chakraborty, S.

    2016-02-01

    High frequency temporal measurements are critical to resolving processes in dynamic coastal environments and geo-stationary satellites enable multiple observations over the course of a day. Such temporal resolution will be important in understanding rapid evolution of coastal physical processes (e.g., tides, wind forcing, water mass movement) as well as short-term changes in biological and chemical properties. The GEO-CAPE (Geostationary Coastal and Air Pollution Events) is one of 17 priority missions identified in the National Research Council's Earth Science Decadal Survey and will provide high spatial and temporal resolution observations of tropospheric trace gases and aerosols and coastal ocean phytoplankton, water quality and biogeochemistry. At present, however there are a limited number of hyperspectral ocean color observations in coastal waters and even fewer time-series observations. Such data sets, particularly when coupled with supporting optical and water property observations, would be highly beneficial in evaluating sensor requirements and algorithm performance. Here, we describe results of comparisons of hyperspectral and multi-spectral radiometric observations deployed at a cabled coastal ocean observatory on the New England continental shelf, the Martha's Vineyard Coastal Observatory (MVCO). The radiometric measurements are complemented by a broad suite of meteorological and hydrographic core measurements as well as efforts providing detailed characterization of changes in phytoplankton community structure with automated submersible flow cytometry and in-water optical properties (chl fluorescence, CDOM fluorescence, backscattering). Our findings illustrate the dynamic nature of this coastal ecosystem and the utility of hyperspectral radiometry and geostationary satellite observations to characterize short term variability in optical and biogeochemical properties of coastal environments.

  4. Spectral radiometric instrumentation and modelling for PV applications

    SciTech Connect

    Cannon, T.W.

    1995-09-01

    This paper describes issues dealing with instrumentation and atmospheric transmission modelling for determining solar spectral irradiance for outdoor photovoltaic (PV) applications. The relevance of these determinations to PV testing and evaluation is discussed with examples.

  5. Impact of the cameras radiometric resolution on the accuracy of determining spectral reflectance coefficients

    NASA Astrophysics Data System (ADS)

    Orych, A.; Walczykowski, P.; Jenerowicz, A.; Zdunek, Z.

    2014-11-01

    Nowadays remote sensing plays a very important role in many different study fields, i.e. environmental studies, hydrology, mineralogy, ecosystem studies, etc. One of the key areas of remote sensing applications is water quality monitoring. Understanding and monitoring of the water quality parameters and detecting different water contaminants is an important issue in water management and protection of whole environment and especially the water ecosystem. There are many remote sensing methods to monitor water quality and detect water pollutants. One of the most widely used method for substance detection with remote sensing techniques is based on usage of spectral reflectance coefficients. They are usually acquired using discrete methods such as spectrometric measurements. These however can be very time consuming, therefore image-based methods are used more and more often. In order to work out the proper methodology of obtaining spectral reflectance coefficients from hyperspectral and multispectral images, it is necessary to verify the impact of cameras radiometric resolution on the accuracy of determination of them. This paper presents laboratory experiments that were conducted using two monochromatic XEVA video sensors (400-1700 nm spectral data registration) with two different radiometric resolutions (12 and 14 bits). In view of determining spectral characteristics from images, the research team used set of interferometric filters. All data collected with multispectral digital video cameras were compared with spectral reflectance coefficients obtained with spectroradiometer. The objective of this research is to find the impact of cameras radiometric resolution on reflectance values in chosen wavelength. The main topic of this study is the analysis of accuracy of spectral coefficients from sensors with different radiometric resolution. By comparing values collected from images acquired with XEVA sensors and with the curves obtained with spectroradiometer it

  6. [VMTBB-Based Spectral Radiometric Calibration of NIR Fiber Coupled Spectrometer].

    PubMed

    Zheng, Feng; Liu, Li-ying; Liu, Xiao-xi; Li, Ye; Shi, Xiao-guang; Zhang, Guo-yu; Huan, Ke-wei

    2015-09-01

    The medium temperature black body (MTBB) is conventional high precision equipment used as spectral radiometric scale in infrared spectral region. However, in near-infrared (NIR) spectral region, there are few papers about spectral radiometric calibration by using MTBB, that is because NIR spectral region is the borderland of its effective spectral region. The main research of this paper is spectral radiometric calibration method by using MTBB in NIR spectral region. Accordingly, this paper is devoted mostly to a discussion of how the calibration precision could be affected by selecting different structural parameters of calibration model. The purpose of this paper is to present the results of research and provide technical reference for improving the traceability in NIR spectral radiometric calibration. In this paper, a NIR fiber coupled spectrometer, whose wavelength range covers from 950 to 1700 nm, has been calibrated by a MTBB with adjustable temperature range from 50 to 1050 °C. Concentrating on calibration process, two key points have been discussed. For one thing, the geometric factors of radiation transfer model of the calibration systems have been compared between traditional structure and fiber direct-coupled structure. Because the fiber direct-coupled model is simple and effective, it has been selected instead of traditional model based on the radiation transfer between two coaxial discs. So, it is an advantaged radiation transfer model for radiometric calibration of fiber coupled spectrometer. For another thing, the relation between calibration accuracy and structural parameters of calibration model has been analyzed intensively. The root cause is scale feature of attribute of calibration data itself, which is the nonlinear structure in scales of spectral data. So, the high precision calibration needs nonlinear calibration model, and the uniform sampling for scale feature is also very important. Selecting sample is an inevitable problem when the

  7. Radiometric Calibration Assessment of Commercial High Spatial Resolution Multispectral Image Products

    NASA Technical Reports Server (NTRS)

    Holekamp, Kara; Aaron, David; Thome, Kurtis

    2006-01-01

    Radiometric calibration of commercial imaging satellite products is required to ensure that science and application communities can better understand their properties. Inaccurate radiometric calibrations can lead to erroneous decisions and invalid conclusions and can limit intercomparisons with other systems. To address this calibration need, satellite at-sensor radiance values were compared to those estimated by each independent team member to determine the sensor's radiometric accuracy. The combined results of this evaluation provide the user community with an independent assessment of these commercially available high spatial resolution sensors' absolute calibration values.

  8. Pre-flight radiometric and spectral calibration of Resourcesat-2A-LISS3* payload

    NASA Astrophysics Data System (ADS)

    Seth, Harish; Detroja, M. P.; Padmanabhan, Deepa; Raj, Vedant; Kumar, Anil; Sarkar, S. S.

    2016-05-01

    Resourcesat-2A is a follow-on mission of Resourcesat-2, belongs to Indian Remote Sensing Program. It is expected to be launched in 2016 and is dedicated mainly to agricultural applications. One of the payloads, LISS3* is a medium resolution (23.5 m) sensor having four multispectral bands from 450 to 1650 nm. These spectral bands are named as B2 (550 nm), B3 (650 nm), B4 (815 nm) and B5 (1625 nm) respectively covering Visible, Near Infrared (NIR) and Short Wave Infrared (SWIR) regions. In order to provide quality data to the user community for long term scientific applications pre-flight ground calibration is carried out. This paper describes pre-flight spectral and radiometric calibration of LISS3* payload and its performance evaluation. Since it is a continuity mission to Resourcesat-2, which was launched in April 2011 so for generating long-term data record and correlation with previous observations, its parameters are compared with Resourcesat-2 LISS3* payload. The main spectral parameters like central wavelength, and pass band is determined using system level spectral response and compared for both the mission and differences are outlined. The next important exercise is pre-flight radiometric calibration, which was carried out in laboratory using a standard integrating sphere traceable to NIST standards. This paper highlights the technique adopted during pre-flight calibration of the radiometric response and performance assessment of all 4 bands of LISS3* in terms of major electro-optical parameters like Signal to Noise Ratio (SNR), Saturation Radiance (SR) etc. The observed SR shows that the sensor can measure spectral radiance from Earth up to 100% albedo.

  9. Lunar Spectral Irradiance and Radiance (LUSI): New Instrumentation to Characterize the Moon as a Space-Based Radiometric Standard

    PubMed Central

    Smith, Allan W.; Lorentz, Steven R.; Stone, Thomas C.; Datla, Raju V.

    2012-01-01

    The need to understand and monitor climate change has led to proposed radiometric accuracy requirements for space-based remote sensing instruments that are very stringent and currently outside the capabilities of many Earth orbiting instruments. A major problem is quantifying changes in sensor performance that occur from launch and during the mission. To address this problem on-orbit calibrators and monitors have been developed, but they too can suffer changes from launch and the harsh space environment. One solution is to use the Moon as a calibration reference source. Already the Moon has been used to remove post-launch drift and to cross-calibrate different instruments, but further work is needed to develop a new model with low absolute uncertainties capable of climate-quality absolute calibration of Earth observing instruments on orbit. To this end, we are proposing an Earth-based instrument suite to measure the absolute lunar spectral irradiance to an uncertainty1 of 0.5 % (k=1) over the spectral range from 320 nm to 2500 nm with a spectral resolution of approximately 0.3 %. Absolute measurements of lunar radiance will also be acquired to facilitate calibration of high spatial resolution sensors. The instruments will be deployed at high elevation astronomical observatories and flown on high-altitude balloons in order to mitigate the effects of the Earth’s atmosphere on the lunar observations. Periodic calibrations using instrumentation and techniques available from NIST will ensure traceability to the International System of Units (SI) and low absolute radiometric uncertainties. PMID:26900523

  10. Status of MODIS spatial and spectral characterization and performance

    NASA Astrophysics Data System (ADS)

    Link, Dan; Wang, Zhipeng; Xiong, Xiaoxiong

    2016-05-01

    Since launch, both Terra and Aqua MODIS instruments have continued to operate and make measurements of the earth's top of atmospheric (TOA) radiances and reflectance. MODIS collects data in 36 spectral bands covering wavelengths from 0.41 to 14.4 μm. These spectral bands and detectors are located on four focal plane assemblies (FPAs). MODIS on-board calibrators (OBC) include a spectro-radiometric calibration assembly (SRCA), which was designed to characterize and monitor sensor spatial and spectral performance, such as on-orbit changes in the band-to-band registration (BBR), modulation transfer function (MTF), spectral band center wavelengths (CW) and bandwidths (BW). In this paper, we provide a status update of MODIS spatial and spectral characterization and performance, following a brief description of SRCA functions and on-orbit calibration activities. Sensor spatial and spectral performance parameters derived from SRCA measurements are introduced and discussed. Results show that on-orbit spatial performance has been very stable for both Terra and Aqua MODIS instruments. The large BBR shifts in Aqua MODIS, an issue identified pre-launch, have remained the same over its entire mission. On-orbit changes in CW and BW are less than 0.5 nm and 1 nm, respectively, for most VIS/NIR spectral bands of both instruments.

  11. Impacts of spectral solar irradiance on inter-sensor radiometric calibrations

    NASA Astrophysics Data System (ADS)

    Wu, D. L.; Marshak, A.; Lee, J. N.; Yang, Y.; Marchenko, S. V.; DeLand, M. T.; Krotkov, N. A.; Pilewskie, P.; Woods, T. N.; Harder, J. W.; Richard, E. C.

    2016-12-01

    Spectral solar irradiance (SSI) is often used to calibrate the radiances of UV-VIS-SWIR bands in Earth remote sensing. Although reflectance factor measurements (upwelling radiance normalized by SSI) are less affected by the SSI accuracy, radiance measurements and inter-sensor calibration are very sensitive to errors in the irradiance spectrum used. Modern reflective solar sensors are able to detect 1-2% errors in radiometric calibration and demand a better (<1%) accuracy of SSI measurements. In this study we analyzed 9 widely used SSI spectra for radiometric calibration evaluation. We found that differences in the so-called "calibrated radiances" could reach as large as +/-2% in VIS-SWIR bands and +/-7% in UV bands, depending on what SSI spectrum is used. In addition, uncertainty also arises from convolution of a higher resolution SSI reference spectrum to an instrument bandwidth. Such a large uncertainty has been a major challenge not only for inter-sensor calibration but also for the SSI measurements themselves. NASA's SORCE (Solar Radiation and Climate Experiment, 2003-present) and future TSIS (Total and Spectral Solar Irradiance Sensor) missions has an objective to provide accurate SSI measurements. While the SORCE SSI accuracy is 2% at present, TSIS-1 (to be launched to International Space Station in late 2017 or early 2018) is tasked to improve the SSI accuracy to 1% or better.

  12. In-flight calibration of the spectral and radiometric characteristics of AVIRIS in 1991

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Conel, James E.; Bruegge, Carol J.; Margolis, Jack S.; Carrere, Veronique; Vane, Gregg; Hoover, Gordon

    1992-01-01

    On 7 Mar. 1991, an in-flight calibration experiment was held at the Ivanpah Playa in southeastern California for the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imaging spectrometer. Five AVIRIS overflights were acquired of a calibration target designated on the Ivanpah Playa surface. At the time of the overflights, the reflectance of the calibration target was measured with a field spectrometer. In addition, the atmospheric optical depths and water vapor abundance were measured from a radiometer station adjacent to the calibration target. These in-situ measurements were used to constrain the MODTRAN radiative transfer code to model the upwelling spectral radiance incident to the sensor aperture during the overflights. Analyses of this modeled radiance in conjunction with the laboratory-calibrated radiance were used to determine the spectral and radiometric calibration of AVIRIS while in flight.

  13. Assessment of Infrared Sounder Radiometric Noise from Analysis of Spectral Residuals

    NASA Astrophysics Data System (ADS)

    Dufour, E.; Klonecki, A.; Standfuss, C.; Tournier, B.; Serio, C.; Masiello, G.; Tjemkes, S.; Stuhlmann, R.

    2016-08-01

    For the preparation and performance monitoring of the future generation of hyperspectral InfraRed sounders dedicated to the precise vertical profiling of the atmospheric state, such as the Meteosat Third Generation hyperspectral InfraRed Sounder, a reliable assessment of the instrument radiometric error covariance matrix is needed.Ideally, an inflight estimation of the radiometrric noise is recommended as certain sources of noise can be driven by the spectral signature of the observed Earth/ atmosphere radiance. Also, unknown correlated noise sources, generally related to incomplete knowledge of the instrument state, can be present, so a caracterisation of the noise spectral correlation is also neeed.A methodology, relying on the analysis of post-retreival spectral residuals, is designed and implemented to derive in-flight the covariance matrix on the basis of Earth scenes measurements. This methodology is successfully demonstrated using IASI observations as MTG-IRS proxy data and made it possible to highlight anticipated correlation structures explained by apodization and micro-vibration effects (ghost). This analysis is corroborated by a parallel estimation based on an IASI black body measurement dataset and the results of an independent micro-vibration model.

  14. Comparison of the spatial and radiometric resolution of ERS and Metop C-band radars

    NASA Astrophysics Data System (ADS)

    Elyouncha, Anis; Neyt, Xavier

    2014-10-01

    ERS-1/2 and Metop-A/B satellites carry a very similar radars operating at similar frequencies (5.3/5.255 GHz) and same polarization (VV). However, the radars on-board the satellites of these two missions differ in the pulse waveform, bandwidth and slightly in geometry. Moreover, the on-board and the on-ground processing is different. This paper investigates the spatial and radiometric resolution of these radars and the resolution enhancement between ERS (1991-2011) and Metop (2006- ) missions. The spatial resolution assessment implies the computation and the comparison of the Spatial Response Function (SRF) of both systems. The SRF involves mainly the antenna gain pattern, the pulse waveform and the different on-board filtering stages. The radiometric resolution depends mainly on the signal to noise ratio (SNR) and the number of averaged independent samples (N). Furthermore, the correlation of the measurement samples in a resolution cell is computed to assess the independence assumption. The metric used to quantify the radiometric accuracy in scatterometry is called Kp which is the relative standard deviation. A comparison of Kp parameter extracted from the nominal products of the two missions confirms the expected performance based on the SNR, N and correlation analysis.

  15. Radiometric Cross-Calibration of the HJ-1B IRS in the Thermal Infrared Spectral Band

    NASA Astrophysics Data System (ADS)

    Sun, K.

    2012-12-01

    The natural calamities occur continually, environment pollution and destruction in a severe position on the earth presently, which restricts societal and economic development. The satellite remote sensing technology has an important effect on improving surveillance ability of environment pollution and natural calamities. The radiometric calibration is precondition of quantitative remote sensing; which accuracy decides quality of the retrieval parameters. Since the China Environment Satellite (HJ-1A/B) has been launched successfully on September 6th, 2008, it has made an important role in the economic development of China. The satellite has four infrared bands; and one of it is thermal infrared. With application fields of quantitative remote sensing in china, finding appropriate calibration method becomes more and more important. Many kinds of independent methods can be used to do the absolute radiometric calibration. In this paper, according to the characteristic of thermal infrared channel of HJ-1B thermal infrared multi-spectral camera, the thermal infrared spectral band of HJ-1B IRS was calibrated using cross-calibration methods based on MODIS data. Firstly, the corresponding bands of the two sensors were obtained. Secondly, the MONDTRAN was run to analyze the influences of different spectral response, satellite view zenith angle, atmosphere condition and temperature on the match factor. In the end, their band match factor was calculated in different temperature, considering the dissimilar band response of the match bands. Seven images of Lake Qinghai in different time were chosen as the calibration data. On the basis of radiance of MODIS and match factor, the IRS radiance was calculated. And then the calibration coefficients were obtained by linearly regressing the radiance and the DN value. We compared the result of this cross-calibration with that of the onboard blackbody calibration, which consistency was good.The maximum difference of brightness temperature

  16. Spatial-Temporal Variation of the Radiometric Color of the Largest Ten Lakes in China

    NASA Astrophysics Data System (ADS)

    Li, J.

    2016-02-01

    The optical properties of inland waters are complicated, limiting the use of remote sensing to monitor inland water quality in large regions over long time periods. The radiometric color of water, reflecting overall water quality, is an important parameter in traditional water quality investigations. In this study, we retrieved the Forel-Ule (FU) class radiometric color parameters from MODIS surface reflectance product (MOD09) image, and analyzed its long term time-series variation in the largest ten lakes in China during 2000-2012. Based on validation by in situ measured reflectance data, the MOD09-derived FU products are reliable, with a linear correlation coefficient of 0.97, RMSE of 1.2, and average relative error of 7.7%. Since FU class is an optical parameter, it can be derived from optical remote sensing data without seasonal and area limitations. The FU class products were used to analyze the spatial and temporal variations of turbidity and trophic states in the ten lakes. The largest ten lakes in China include typical types with different optical properties, so the FU class can also be used to assess the quality of other inland waters. The FU class retrieval method can also be applied to other remote sensing data after a simple normalization process. As a result, the FU class radiometric color can be used to assess inland water quality in large regions over long time periods.

  17. Apparatus description and data analysis of a radiometric technique for measurements of spectral and total normal emittance

    NASA Technical Reports Server (NTRS)

    Edwards, S. F.; Kantsios, A. G.; Voros, J. P.; Stewart, W. F.

    1975-01-01

    The development of a radiometric technique for determining the spectral and total normal emittance of materials heated to temperatures of 800, 1100, and 1300 K by direct comparison with National Bureau of Standards (NBS) reference specimens is discussed. Emittances are measured over the spectral range of 1 to 15 microns and are statistically compared with NBS reference specimens. Results are included for NBS reference specimens, Rene 41, alundum, zirconia, AISI type 321 stainless steel, nickel 201, and a space-shuttle reusable surface insulation.

  18. Improved capabilities of the Chinese high-resolution remote sensing satellite GF-1 for monitoring suspended particulate matter (SPM) in inland waters: Radiometric and spatial considerations

    NASA Astrophysics Data System (ADS)

    Li, Jian; Chen, Xiaoling; Tian, Liqiao; Huang, Jue; Feng, Lian

    2015-08-01

    Dominated by high dynamic and small-scale variability, remote sensing of inland or coastal waters is frequently impended by insufficient spatial resolutions from conventional ocean color sensors. With the urgent need and the rapid progress in high-resolution earth observation systems (HR), it is critical to assess the capabilities of HR in inland water monitoring. In this study, the radiometric and spatial performance of the Chinese high-resolution GF-1 Wide Field Imager (WFI) data for water quality monitoring were evaluated in term of the signal-to-noise ratio (SNR), sensitivity to suspended particulate matter (SPM) variations and spatial depiction ability. The SNR was statistically estimated from variable moving window method, and the radiometric sensitivity was simulated using the Moderate Resolution Atmospheric Transmission (MODTRAN) under varied surface and atmospheric conditions. Results indicated that both the SNR and the radiometric sensitivity of the GF-1 WFI were enhanced by 3-5 times than its predecessor (Chinese HJ-1 CCD) or Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and were comparable to Landsat 8 Operational Land Imager (OLI) and Moderate Resolution Imaging Spectroradiometer (MODIS) medium-resolution bands (250 and 500 m), which have been extensively applied in inland water environment monitoring. Cross comparisons demonstrated high consistency of the spatial distribution and concentration of SPM maps between GF-1 WFI and Landsat 8 OLI. Furthermore, more than 75% of the spatial variations in high turbid waters were resolved from GF-1 WFI data, whereas the ability dropped to 40% when the spatial resolution was degraded to 250 m (MODIS-like sensors). Overall, GF-1 WFI is extraordinarily promising with an enhanced SNR, an increased spectral sensitivity to SPM variations and an advanced spatial resolution. With the ongoing plans of the successive GF series (2-7), the findings would serve as a reference for forthcoming applications, and are critical

  19. SPATIAL AND SPECTRAL RESOLUTION IN GEOBOTANY.

    USGS Publications Warehouse

    Milton, Nancy M.; Mouat, D.A.

    1984-01-01

    Remotely sensed data are now available from a wide variety of instruments, each data set having a particular spectral and spatial resolution. The changes in vegetation associated with changes in lithology or the presence of mineral deposits can also occur at different scales. The task of geobotanical remote sensing is to choose or adapt the remotely sensed data to the appropriate geobotanical technique to solve the geological problem of interest. Examples are given of a number of applications of data sets of different spectral and spatial resolution. The relative importance of spectral and spatial resolution is discussed.

  20. Effect of radiometric errors on accuracy of temperature-profile measurement by spectral scanning using absorption-emission pyrometry

    NASA Technical Reports Server (NTRS)

    Buchele, D. R.

    1972-01-01

    The spectral-scanning method may be used to determine the temperature profile of a jet- or rocket-engine exhaust stream by measurements of gas radiation and transmittance, at two or more wavelengths. A single, fixed line of sight is used, using immobile radiators outside of the gas stream, and there is no interference with the flow. At least two sets of measurements are made, each set consisting of the conventional three radiometric measurements of absorption-emission pyrometry, but each set is taken over a different spectral interval that gives different weight to the radiation from a different portion of the optical path. Thereby, discrimination is obtained with respect to location along the path. A given radiometric error causes an error in computed temperatures. The ratio between temperature error and radiometric error depends on profile shape, path length, temperature level, and strength of line absorption, and the absorption coefficient and its temperature dependency. These influence the choice of wavelengths, for any given gas. Conditions for minimum temperature error are derived. Numerical results are presented for a two-wavelength measurement on a family of profiles that may be expected in a practical case of hydrogen-oxygen combustion. Under favorable conditions, the fractional error in temperature approximates the fractional error in radiant-flux measurement.

  1. Extraction of auxiliary data from AVIRIS distribution tape for spectral, radiometric, and geometric quality assessment

    NASA Technical Reports Server (NTRS)

    Meyer, Peter; Green, Robert O.; Chrien, Thomas G.

    1993-01-01

    Remotely sensed data are affected by system (sensor and platform), and scene related effects. For quantitative investigations the spectral, radiometric characteristics of the system and scene have to be known. The relevant effects and their possible influence on an image have to be specifically determined for every remote sensing system and adequate description parameters need to be updated and reported on a regular basis as they are carried out, e.g., for the AVIRIS system. It is evident that the strength of the influence of similar effects in very dependent on the accessibility of auxiliary information about such sensor systems. Degradation in a spaceborne system can normally be just reported and cannot be corrected. In contrast, an airborne sensor can be evaluated, maintained and improved periodically. Such maintenance efforts are particularly important because airborne systems are exposed to extreme and changing environments. These include tens of takeoffs and landing each year as well as extreme changes in temperature and humidity on the tarmac and in flight. For the AVIRIS system there are environmental stresses such as changes in temperature, air pressure, humidity, vibration of the platform or scene-related reasons like atmospheric conditions, and topography. The information contained in the auxiliary files included with the AVIRIS data can be used to assess these effects and compensate for them. In addition the spectral, radiometer and geometric calibration data contained in the auxiliary file are required for quantitative analysis of the data. The paper describes tools to access the auxiliary information that characterizes the AVIRIS system. These tools allow the examination of parameters that may impact the quality of the measured AVIRIS image. An example of the use of this auxiliary data was carried out with regard to a parametric geocoding approach. Emphasis is placed on the reported auxiliary information that describes the geometric character of the

  2. Study on spectral/radiometric characteristics of the Thematic Mapper for land use applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A.; Metzler, M. D. (Principal Investigator); Crist, E. P.

    1983-01-01

    Previous characterization of scan-related low-frequency noise was extended and refined through detailed analysis of shutter calibration data on CCT-ADDS tapes and reflective-band data from nighttime acquisitions. A recommended correction procedure was identified that uses calibration shutter data both as a diagnostic and to obtain correction values. Through comparison of coincident TM and MSS data, illustrations of the added information content of TM data for agricultural applications were developed. The capability of improved spatial resolution to better define boundaries and to resolve spatial details is shown. Spectral analysis of tasseled-cap transformations of TM and MSS data shows high correlation between greenness features, greater signal range for TM, and indications that a subset of TM bands could accurately simulate MSS data, if required.

  3. Electronic transport characterization of silicon wafers by spatially resolved steady-state photocarrier radiometric imaging

    SciTech Connect

    Wang, Qian; Li, Bincheng

    2015-09-28

    Spatially resolved steady-state photocarrier radiometric (PCR) imaging technique is developed to characterize the electronic transport properties of silicon wafers. Based on a nonlinear PCR theory, simulations are performed to investigate the effects of electronic transport parameters (the carrier lifetime, the carrier diffusion coefficient, and the front surface recombination velocity) on the steady-state PCR intensity profiles. The electronic transport parameters of an n-type silicon wafer are simultaneously determined by fitting the measured steady-state PCR intensity profiles to the three-dimensional nonlinear PCR model. The determined transport parameters are in good agreement with the results obtained by the conventional modulated PCR technique with multiple pump beam radii.

  4. On-ground characterization of Rosetta/VIRTIS-M. II. Spatial and radiometric calibrations

    SciTech Connect

    Filacchione, G.; Ammannito, E.; Coradini, A.; Capaccioni, F.; Piccioni, G.; De Sanctis, M. C.; Dami, M.; Barbis, A.

    2006-10-15

    After having considered the spectral and geometrical performances of the Rosetta/VIRTIS-M experiment, we complete here the analysis by evaluating quantitatively the flat-field and radiometric responses. The purpose of this work is to retrieve the flat-field matrix necessary to homogenize the focal plane response. Moreover, the most important result is the determination of the instrument transfer function that allows to convert digital numbers in physical units of spectral radiance (W m{sup -2} {mu}m{sup -1} sterad{sup -1}). The strategy adopted to organize measurement sequence, a basic description of the on-ground experimental setups and the analysis of the collected data, is included in this article. An analysis of the instrumental stability has been performed as well by examining how the internal calibration data are affected by environmental conditions. These data allow to evaluate the cumulative effects of thermal and vibrational stresses on the instrumental performances: up to now we have verified that this effect is negligible. Finally the basic calibration pipeline used to calibrate in-flight data with on-ground parameters is fully described.

  5. Spectrally-spatial fourier-holography.

    PubMed

    Kalenkov, S G; Kalenkov, G S; Shtanko, A E

    2013-10-21

    We propose a novel method to obtain non-lens holographic images of micro-objects in white light with diffraction limit quality, based on fourier-spectroscopy principles. We developed a simple method for numerical acquisition of digital holograms of micro-objects at any spectral component from the set of two-dimensional interferograms, registered by fourier-spectrometer. In our experiments we used spectrally-spatial holographic fourier-spectrometer (SSHFS), equipped with supercontinuum light source and CCD camera for registration. Holographic images of several test objects acquired experimentally at different spectral components are presented. Visualization of local spatially-spectral inhomogeneities of micro-objects is discussed through the example of silver berry scaly hair sample.

  6. Study on spectral/radiometric characteristics of the Thematic Mapper for land use applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A. (Principal Investigator); Metzler, M. D.

    1984-01-01

    Progress under the LANDSAT-4 and 5 Image Data Quality Assessment program for the Thematic Mapper is described. An initial screening of LANDSAT-5 data is performed. Tools are developed to allow access to TIPS-format data. Analysis of scan direction related signal droop is resumed with detailed analysis of nighttime data. A new mathematical model is developed to describe the effect. Coherent noise of a lower frequency than previously reported is discovered and analyzed. Coincident LANDSAT-4 TM and MSS data are analyzed to improve understanding of radiometric relationships between similar wavebands in the two sensors.

  7. Study of spectral/radiometric characteristics of the Thematic Mapper for land use applications

    NASA Technical Reports Server (NTRS)

    Malila, W. A. (Principal Investigator); Metzler, M. D.

    1984-01-01

    Progress during the Environmental Research Institute of Michigan-ERIM's and 5 image data quality assessment program for the thematic mapper is described. Analyses of LANDSAT 5 TM radiometric characteristics were performed. Effects which had earlier been found in LANDSAT 4 TM data were found to be present in LANDSAT 5 data as well, including: (1) scan direction related signal droop; (2) scan correlated level shifts; and (3) low frequency coherent noise. Coincident LANDSAT 4 and 5 raw TM data were analyzed, and band by band relationships between the two sensors were derived. Earlier efforts which developed an information theoretic measure of multispectral information content were continued, comparing TM and MSS information content.

  8. Instrumentation For Detector Spectral / Spatial Uniformity Measurements

    NASA Astrophysics Data System (ADS)

    Craft, Ronald W.; Bronson, Robert M.

    1989-09-01

    The information presented in this report describes an instrument which is used for precision measurements of detector spectral response and spatial response. Emphasis will be placed on detector spatial uniformity measurements. To allow spatial uniformity testing at selected wavelengths, an instrument was designed by applying existing spectral response instrumentation technology with the addition of special exit optics, a dual axis motorized positioning table, and supporting software. Supporting components consisted of a computer controlled radiometer and a monochromator with a high intensity light source attached. Spectral response is determined by measuring the wavelength response photosensitivity of a stationary specimen to the irradiance of a calibrated monochromatic light source over the wavelength range of interest at evenly spaced intervals. Data is presented in a pictorial format by graphing the RESPONSE versus the WAVELENGTH. Detector spatial response is determined by measuring the variation in photosensitivity over the surface of the test detector by moving the detector in an X,Y grid at evenly spaced intervals under a small monochromatic spot of light. Several versions of the instrument were built and test results are provided which represent data from the spatial uniformity testing of Ge, PbS, and PbSe detectors. Data acquired is presented as a 3-Dimensional surface map by plotting the RESPONSE versus the X POSITION versus the Y POSITION.

  9. SeaWiFS technical report series. Volume 23: SeaWiFS prelaunch radiometric calibration and spectral characterization

    NASA Technical Reports Server (NTRS)

    Barnes, Robert A.; Holmes, Alan W.; Barnes, William L.; Esaias, Wayne E.; Mcclain, Charles R.; Svitek, Tomas; Hooker, Stanford B.; Firestone, Elaine R.; Acker, James G.

    1994-01-01

    Based on the operating characteristics of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), calibration equations have been developed that allow conversion of the counts from the radiometer into Earth-existing radiances. These radiances are the geophysical properties the instrument has been designed to measure. SeaWiFS uses bilinear gains to allow high sensitivity measurements of ocean-leaving radiances and low sensitivity measurements of radiances from clouds, which are much brighter than the ocean. The calculation of these bilinear gains is central to the calibration equations. Several other factors within these equations are also included. Among these are the spectral responses of the eight SeaWiFS bands. A band's spectral response includes the ability of the band to isolate a portion of the electromagnetic spectrum and the amount of light that lies outside of that region. The latter is termed out-of-band response. In the calibration procedure, some of the counts from the instrument are produced by radiance in the out-of-band region. The number of those counts for each band is a function of the spectral shape of the source. For the SeaWiFS calibration equations, the out-of-band responses are converted from those for the laboratory source into those for a source with the spectral shape of solar flux. The solar flux, unlike the laboratory calibration, approximates the spectral shape of the Earth-existing radiance from the oceans. This conversion modifies the results from the laboratory radiometric calibration by 1-4 percent, depending on the band. These and other factors in the SeaWiFS calibration equations are presented here, both for users of the SeaWiFS data set and for researchers making ground-based radiance measurements in support of Sea WiFS.

  10. Mesoscale, Radiometrically Referenced, Multi-Temporal Hyperspectral Data for Co2 Leak Detection by Locating Spatial Variation of Biophysically Relevant Parameters

    NASA Astrophysics Data System (ADS)

    McCann, Cooper Patrick

    Low-cost flight-based hyperspectral imaging systems have the potential to provide valuable information for ecosystem and environmental studies as well as aide in land management and land health monitoring. This thesis describes (1) a bootstrap method of producing mesoscale, radiometrically-referenced hyperspectral data using the Landsat surface reflectance (LaSRC) data product as a reference target, (2) biophysically relevant basis functions to model the reflectance spectra, (3) an unsupervised classification technique based on natural histogram splitting of these biophysically relevant parameters, and (4) local and multi-temporal anomaly detection. The bootstrap method extends standard processing techniques to remove uneven illumination conditions between flight passes, allowing the creation of radiometrically self-consistent data. Through selective spectral and spatial resampling, LaSRC data is used as a radiometric reference target. Advantages of the bootstrap method include the need for minimal site access, no ancillary instrumentation, and automated data processing. Data from a flight on 06/02/2016 is compared with concurrently collected ground based reflectance spectra as a means of validation achieving an average error of 2.74%. Fitting reflectance spectra using basis functions, based on biophysically relevant spectral features, allows both noise and data reductions while shifting information from spectral bands to biophysical features. Histogram splitting is used to determine a clustering based on natural splittings of these fit parameters. The Indian Pines reference data enabled comparisons of the efficacy of this technique to established techniques. The splitting technique is shown to be an improvement over the ISODATA clustering technique with an overall accuracy of 34.3/19.0% before merging and 40.9/39.2% after merging. This improvement is also seen as an improvement of kappa before/after merging of 24.8/30.5 for the histogram splitting technique

  11. TES Level 1 Algorithms: Interferogram Processing, Geolocation, Radiometric, and Spectral Calibration

    NASA Technical Reports Server (NTRS)

    Worden, Helen; Beer, Reinhard; Bowman, Kevin W.; Fisher, Brendan; Luo, Mingzhao; Rider, David; Sarkissian, Edwin; Tremblay, Denis; Zong, Jia

    2006-01-01

    The Tropospheric Emission Spectrometer (TES) on the Earth Observing System (EOS) Aura satellite measures the infrared radiance emitted by the Earth's surface and atmosphere using Fourier transform spectrometry. The measured interferograms are converted into geolocated, calibrated radiance spectra by the L1 (Level 1) processing, and are the inputs to L2 (Level 2) retrievals of atmospheric parameters, such as vertical profiles of trace gas abundance. We describe the algorithmic components of TES Level 1 processing, giving examples of the intermediate results and diagnostics that are necessary for creating TES L1 products. An assessment of noise-equivalent spectral radiance levels and current systematic errors is provided. As an initial validation of our spectral radiances, TES data are compared to the Atmospheric Infrared Sounder (AIRS) (on EOS Aqua), after accounting for spectral resolution differences by applying the AIRS spectral response function to the TES spectra. For the TES L1 nadir data products currently available, the agreement with AIRS is 1 K or better.

  12. High-spectral-resolution radiometric measurements of aerosol extinction over an urban region in India

    NASA Astrophysics Data System (ADS)

    Devara, P. C. S.; Ramkumar, M.; Maheskumar, R. S.; Pandithurai, G.

    2001-06-01

    Concurrent observations of aerosol optical depth (AOD) were carried out using a high-spectral-resolution radiometer (HSRR) and solar radiometer (SR) at the Indian Institute of Tropical Meteorology (IITM), Pune, India, on all clear-sky days available during November 1995-February 1996. The HSRR observations were collected at 5 nm intervals throughout the 400-700 nm spectrum while the SR measurements were made at discrete wavelengths of 400, 600, 940, 1060 and 1630 nm. In order to study the effect of integrated spectral observations on the derived AODs as compared to such depths from a single spectrum, multi-spectral observations at 2 nm intervals were collected. The AODs and their wavelength dependence from the HSRR and SR are compared and fairly good agreement found. The HSRR derived AODs at 400 nm and 700 nm from the present data sets are compared with those obtained during the winters of 1993-94 and 1994-95. The results reveal greater AODs, indicating abundance of aerosol particle concentration, during 1995-96 as compared to 1993-94 and 1994-95.

  13. Metaoptics for Spectral and Spatial Beam Manipulation

    NASA Astrophysics Data System (ADS)

    Raghu Srimathi, Indumathi

    Laser beam combining and beam shaping are two important areas with applications in optical communications, high power lasers, and atmospheric propagation studies. In this dissertation, metaoptical elements have been developed for spectral and spatial beam shaping, and multiplexing. Beams carrying orbital angular momentum (OAM), referred to as optical vortices, have unique propagation properties. Optical vortex beams carrying different topological charges are orthogonal to each other and have low inter-modal crosstalk which allows for them to be (de)multiplexed. Efficient spatial (de)multiplexing of these beams have been carried out by using diffractive optical geometrical coordinate transformation elements. The spatial beam combining technique shown here is advantageous because the efficiency of the system is not dependent on the number of OAM states being combined. The system is capable of generating coaxially propagating beams in the far-field and the beams generated can either be incoherently or coherently multiplexed with applications in power scaling and dynamic intensity profile manipulations. Spectral beam combining can also be achieved with the coordinate transformation elements. The different wavelengths emitted by fiber sources can be spatially overlapped in the far-field plane and the generated beams are Bessel-Gauss in nature with enhanced depth of focus properties. Unique system responses and beam shapes in the far-field can be realized by controlling amplitude, phase, and polarization at the micro-scale. This has been achieved by spatially varying the structural parameters at the subwavelength scale and is analogous to local modification of material properties. With advancements in fabrication technology, it is possible to control not just the lithographic process, but also the deposition process. In this work, a unique combination of spatial structure variations in conjunction with the conformal coating properties of an atomic layer deposition tool

  14. High Altitude Measurements of Radiance at High Spectral and Spatial Resolution for SIMBIOS Sensor Calibration, Validation, and Intercomparisons. Chapter 11

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Pavri, Betina; Chrien, Thomas G.

    2001-01-01

    The successful combination of data from different ocean color sensors depends on the correct interpretation of signal from each of these sensors. Ideally, the sensor measured signals are calibrated to geophysical units of spectral radiance, and sensor artifacts are removed and corrected. The calibration process resamples the signal into a common radiometric data space so that subsequent ocean color algorithms that are applied to the data are based on physical processes and are inherently sensor independent. The objective of this project is to calibrate and validate the on-orbit radiometric characteristics of Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) with underflights of NASA's calibrated Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). This objective is feasible because AVIRIS measures the same spectral range as SeaWIFS at higher spectral resolution. In addition to satellite sensor underflights, the AVIRIS project has supported comparison and analysis of the radiometric calibration standards used for AVIRIS and SeaWIFS. To date, both the OCTS and SeaWIFS satellite sensors have been underflown by AVIRIS with matching spectral, spatial, geometric, radiometric, and temporal domains. The calibration and validation objective of this project is pursued for the following reasons: (1) Calibration is essential for the quantitative use of SeaWIFS and other SIMBIOS (Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies) sensor data; (2) Calibration in the laboratory of spaceborne sensors is challenging; (3) Satellite sensors are subjected aging on the ground and to trauma during launch; (4) The Earth orbit environment is significantly different than the laboratory calibration environment; (5) Through years of effort AVIRIS has been demonstrated to be well calibrated; and (6) AVIRIS can match the spectral and spatial observation characteristics near the top of the atmosphere at the time of SeaWIFS measurements.

  15. High Altitude Measurements of Radiance at High Spectral and Spatial Resolution for SIMBIOS Sensor Calibration, Validation, and Intercomparisons. Chapter 11

    NASA Technical Reports Server (NTRS)

    Green, Robert O.; Pavri, Betina; Chrien, Thomas G.

    2001-01-01

    The successful combination of data from different ocean color sensors depends on the correct interpretation of signal from each of these sensors. Ideally, the sensor measured signals are calibrated to geophysical units of spectral radiance, and sensor artifacts are removed and corrected. The calibration process resamples the signal into a common radiometric data space so that subsequent ocean color algorithms that are applied to the data are based on physical processes and are inherently sensor independent. The objective of this project is to calibrate and validate the on-orbit radiometric characteristics of Sea-Viewing Wide Field-of-view Sensor (SeaWiFS) with underflights of NASA's calibrated Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). This objective is feasible because AVIRIS measures the same spectral range as SeaWIFS at higher spectral resolution. In addition to satellite sensor underflights, the AVIRIS project has supported comparison and analysis of the radiometric calibration standards used for AVIRIS and SeaWIFS. To date, both the OCTS and SeaWIFS satellite sensors have been underflown by AVIRIS with matching spectral, spatial, geometric, radiometric, and temporal domains. The calibration and validation objective of this project is pursued for the following reasons: (1) Calibration is essential for the quantitative use of SeaWIFS and other SIMBIOS (Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies) sensor data; (2) Calibration in the laboratory of spaceborne sensors is challenging; (3) Satellite sensors are subjected aging on the ground and to trauma during launch; (4) The Earth orbit environment is significantly different than the laboratory calibration environment; (5) Through years of effort AVIRIS has been demonstrated to be well calibrated; and (6) AVIRIS can match the spectral and spatial observation characteristics near the top of the atmosphere at the time of SeaWIFS measurements.

  16. Spectral deconvolution and operational use of stripping ratios in airborne radiometrics.

    PubMed

    Allyson, J D; Sanderson, D C

    2001-01-01

    Spectral deconvolution using stripping ratios for a set of pre-defined energy windows is the simplest means of reducing the most important part of gamma-ray spectral information. In this way, the effective interferences between the measured peaks are removed, leading, through a calibration, to clear estimates of radionuclide inventory. While laboratory measurements of stripping ratios are relatively easy to acquire, with detectors placed above small-scale calibration pads of known radionuclide concentrations, the extrapolation to measurements at altitudes where airborne survey detectors are used bring difficulties such as air-path attenuation and greater uncertainties in knowing ground level inventories. Stripping ratios are altitude dependent, and laboratory measurements using various absorbers to simulate the air-path have been used with some success. Full-scale measurements from an aircraft require a suitable location where radionuclide concentrations vary little over the field of view of the detector (which may be hundreds of metres). Monte Carlo simulations offer the potential of full-scale reproduction of gamma-ray transport and detection mechanisms. Investigations have been made to evaluate stripping ratios using experimental and Monte Carlo methods.

  17. Spatially resolved spectral-imaging device

    DOEpatents

    Bloom, Joshua Simon; Tyson, John Anthony

    2016-02-09

    A spatially resolved spectral device comprising a dispersive array to receive an incident light comprising a principal ray. The dispersive array comprising a plurality of dichroic layers, each of the plurality of dichroic layers disposed in a path of a direction of the principal ray. Each of the plurality of dichroic layers configured to at least one of reflect or transmit a different wavelength range of the incident light. The device further comprising a detection array operatively coupled with the dispersive array. The detection array comprising a photosensitive component including a plurality of detection pixels, each of the plurality of detection pixels having a light-receiving surface disposed parallel to the direction of the principal ray to detect a respective one of the different wavelength ranges of incident light reflected from a corresponding one of the plurality of dichroic layers.

  18. Spectral radiant power measurements of VUV and soft x-ray sources using the electron storage ring BESSY as a radiometric standard source.

    PubMed

    Fischer, J; Kühne, M; Wende, B

    1984-12-01

    A method is described for measuring the spectral radiant power of VUV and soft x-ray sources using the electron storage ring BESSY as a radiometric standard source of calculable spectral radiant power and degree of polarization. An ellipsoidal grazing incidence mirror stigmatically images the stored electrons or the source under investigation in equal optical conditions into a toroidal grating monochromator. The monochromator can be rotated around its optical axis in UHV conditions to account for different degrees of polarization of the two sources. The accuracy presently available with this method is demonstrated by a measurement of the spectral concentration of radiant intensity of a laser-produced tungsten plasma in the wavelength range between 7 and 100 nm with an overall uncertainty of 10%. A detailed analysis of the contributions to this uncertainty shows that the major part of it is caused by the presently uncertain knowledge of the polarizing properties of the radiometric instrumentation and by the uncertainty of the correction procedure which accounts for the influence of higher diffraction orders of the monochromator grating. The results of the radiation measurements of the laser-produced tungsten plasma let us expect that this source type has the potential to serve as a radiometric transfer standard in the VUV and soft x-ray range below 100 nm.

  19. [Laser-based radiometric calibration].

    PubMed

    Li, Zhi-gang; Zheng, Yu-quan

    2014-12-01

    Increasingly higher demands are put forward to spectral radiometric calibration accuracy and the development of new tunable laser based spectral radiometric calibration technology is promoted, along with the development of studies of terrestrial remote sensing, aeronautical and astronautical remote sensing, plasma physics, quantitative spectroscopy, etc. Internationally a number of national metrology scientific research institutes have built tunable laser based spectral radiometric calibration facilities in succession, which are traceable to cryogenic radiometers and have low uncertainties for spectral responsivity calibration and characterization of detectors and remote sensing instruments in the UK, the USA, Germany, etc. Among them, the facility for spectral irradiance and radiance responsivity calibrations using uniform sources (SIRCCUS) at the National Institute of Standards and Technology (NIST) in the USA and the Tunable Lasers in Photometry (TULIP) facility at the Physikalisch-Technische Bundesanstalt (PTB) in Germany have more representatives. Compared with lamp-monochromator systems, laser based spectral radiometric calibrations have many advantages, such as narrow spectral bandwidth, high wavelength accuracy, low calibration uncertainty and so on for radiometric calibration applications. In this paper, the development of laser-based spectral radiometric calibration and structures and performances of laser-based radiometric calibration facilities represented by the National Physical Laboratory (NPL) in the UK, NIST and PTB are presented, technical advantages of laser-based spectral radiometric calibration are analyzed, and applications of this technology are further discussed. Laser-based spectral radiometric calibration facilities can be widely used in important system-level radiometric calibration measurements with high accuracy, including radiance temperature, radiance and irradiance calibrations for space remote sensing instruments, and promote the

  20. Small satellite radiometric measurements

    SciTech Connect

    Weber, P.G.

    1991-01-01

    A critical need for the Mission to Planet Earth is to provide continuous, well-calibrated radiometric data for the radiation budget. This paper describes a new, compact, flexible radiometer which will provide both spectrally integrated data and data in selected spectral bands. The radiometer design is suitable for use on small satellites, aircraft, or remotely piloted vehicles (RPVs). 12 refs., 2 figs.

  1. Diffusing screen for on-board radiometric calibration of the stereo-spectral-imaging system ARGUS for Mars 94/96 mission.

    NASA Astrophysics Data System (ADS)

    Morozova, S. P.; Sapritsky, V. I.; Morozov, P. A.; Novitsky, A. V.; Khlevnoy, B. B.; Lisiansky, B. E.; Tarnopolsky, V. I.; Belousov, A. V.

    1996-05-01

    A new stereo-spectral-imaging system, ARGUS, has been developed for the Mars 94/96 mission and consists of three videospectrometers with a wide field-of-view covering the spectral range 320 nm to 5200 nm. The on-board radiometric calibration is based on a diffusing target illuminated by the Sun's radiation. The provision for a common target for all the videospectrometers of the ARGUS system allows an intercomparison of instruments to be carried out in addition to individual calibration verification. The development and testing of the target for on-board radiometric calibration is described and techniques for preparing the target surface are given. A brief description of the setup for measurements of the spectral and angular response of the target reflectivity is presented, together with results of the spectral and angular response of the target reflectivity, for an angle of incidence of -70° (relative to the normal) and at viewing angles from 0° to +60° at 2° intervals. The bidirectional reflectance factor of the target is reported for the spectral range 320 nm to 5200 nm at an angle of incidence of -70° and at a viewing angle of +20°.

  2. Algorithm for automatic image dodging of unmanned aerial vehicle images using two-dimensional radiometric spatial attributes

    NASA Astrophysics Data System (ADS)

    Li, Wenzhuo; Sun, Kaimin; Li, Deren; Bai, Ting

    2016-07-01

    Unmanned aerial vehicle (UAV) remote sensing technology has come into wide use in recent years. The poor stability of the UAV platform, however, produces more inconsistencies in hue and illumination among UAV images than other more stable platforms. Image dodging is a process used to reduce these inconsistencies caused by different imaging conditions. We propose an algorithm for automatic image dodging of UAV images using two-dimensional radiometric spatial attributes. We use object-level image smoothing to smooth foreground objects in images and acquire an overall reference background image by relative radiometric correction. We apply the Contourlet transform to separate high- and low-frequency sections for every single image, and replace the low-frequency section with the low-frequency section extracted from the corresponding region in the overall reference background image. We apply the inverse Contourlet transform to reconstruct the final dodged images. In this process, a single image must be split into reasonable block sizes with overlaps due to large pixel size. Experimental mosaic results show that our proposed method reduces the uneven distribution of hue and illumination. Moreover, it effectively eliminates dark-bright interstrip effects caused by shadows and vignetting in UAV images while maximally protecting image texture information.

  3. Spectrally and Radiometrically Stable Wide-Band on Board Calibration Source for In-Flight Data Validation in Imaging Spectroscopy Applications

    NASA Technical Reports Server (NTRS)

    Coles, J. B.; Richardson, Brandon S.; Eastwood, Michael L.; Sarture, Charles M.; Quetin, Gregory R.; Hernandez, Marco A.; Kroll, Linley A.; Nolte, Scott H.; Porter, Michael D.; Green, Robert O.

    2011-01-01

    The quality of the quantitative spectral data collected by an imaging spectrometer instrument is critically dependent upon the accuracy of the spectral and radiometric calibration of the system. In order for the collected spectra to be scientifically useful, the calibration of the instrument must be precisely known not only prior to but during data collection. Thus, in addition to a rigorous in-lab calibration procedure, the airborne instruments designed and built by the NASA/JPL Imaging Spectroscopy Group incorporate an on board calibrator (OBC) system with the instrument to provide auxiliary in-use system calibration data. The output of the OBC source illuminates a target panel on the backside of the foreoptics shutter both before and after data collection. The OBC and in-lab calibration data sets are then used to validate and post-process the collected spectral image data. The resulting accuracy of the spectrometer output data is therefore integrally dependent upon the stability of the OBC source. In this paper we describe the design and application of the latest iteration of this novel device developed at NASA/JPL which integrates a halogen-cycle source with a precisely designed fiber coupling system and a fiber-based intensity monitoring feedback loop. The OBC source in this Airborne Testbed Spectrometer was run over a period of 15 hours while both the radiometric and spectral stabilities of the output were measured and demonstrated stability to within 1% of nominal.

  4. Calibration chain design based on integrating sphere transfer radiometer for SI-traceable on-orbit spectral radiometric calibration and its uncertainty analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Wei-Ning; Fang, Wei; Sun, Li-Wei; Cui, Li-Hong; Wang, Yu-Peng

    2016-09-01

    In order to satisfy the requirement of SI-traceable on-orbit absolute radiation calibration transfer with high accuracy for satellite remote sensors, a transfer chain consisting of a fiber coupling monochromator (FBM) and an integrating sphere transfer radiometer (ISTR) was designed in this paper. Depending on the Sun, this chain based on detectors provides precise spectral radiometric calibration and measurement to spectrometers in the reflective solar band (RSB) covering 300-2500 nm with a spectral bandwidth of 0.5-6 nm. It shortens the traditional chain based on lamp source and reduces the calibration uncertainty from 5% to 0.5% by using the cryogenic radiometer in space as a radiometric benchmark and trap detectors as secondary standard. This paper also gives a detailed uncertainty budget with reasonable distribution of each impact factor, including the weak spectral signal measurement with uncertainty of 0.28%. According to the peculiar design and comprehensive uncertainty analysis, it illustrates that the spectral radiance measurement uncertainty of the ISTR system can reach to 0.48%. The result satisfies the requirements of SI-traceable on-orbit calibration and has wider significance for expanding the application of the remote sensing data with high-quality. Project supported by the National Natural Science Foundation of China (Grant No. 41474161) and the National High-Technology Program of China (Grant No. 2015AA123703).

  5. Spectrally and Radiometrically Stable Wide-Band on Board Calibration Source for In-Flight Data Validation in Imaging Spectroscopy Applications

    NASA Technical Reports Server (NTRS)

    Coles, J. B.; Richardson, Brandon S.; Eastwood, Michael L.; Sarture, Charles M.; Quetin, Gregory R.; Hernandez, Marco A.; Kroll, Linley A.; Nolte, Scott H.; Porter, Michael D.; Green, Robert O.

    2011-01-01

    The quality of the quantitative spectral data collected by an imaging spectrometer instrument is critically dependent upon the accuracy of the spectral and radiometric calibration of the system. In order for the collected spectra to be scientifically useful, the calibration of the instrument must be precisely known not only prior to but during data collection. Thus, in addition to a rigorous in-lab calibration procedure, the airborne instruments designed and built by the NASA/JPL Imaging Spectroscopy Group incorporate an on board calibrator (OBC) system with the instrument to provide auxiliary in-use system calibration data. The output of the OBC source illuminates a target panel on the backside of the foreoptics shutter both before and after data collection. The OBC and in-lab calibration data sets are then used to validate and post-process the collected spectral image data. The resulting accuracy of the spectrometer output data is therefore integrally dependent upon the stability of the OBC source. In this paper we describe the design and application of the latest iteration of this novel device developed at NASA/JPL which integrates a halogen-cycle source with a precisely designed fiber coupling system and a fiber-based intensity monitoring feedback loop. The OBC source in this Airborne Testbed Spectrometer was run over a period of 15 hours while both the radiometric and spectral stabilities of the output were measured and demonstrated stability to within 1% of nominal.

  6. Towards IASI-New Generation (IASI-NG): impact of improved spectral resolution and radiometric noise on the retrieval of thermodynamic, chemistry and climate variables

    NASA Astrophysics Data System (ADS)

    Crevoisier, C.; Clerbaux, C.; Guidard, V.; Phulpin, T.; Armante, R.; Barret, B.; Camy-Peyret, C.; Chaboureau, J.-P.; Coheur, P.-F.; Crépeau, L.; Dufour, G.; Labonnote, L.; Lavanant, L.; Hadji-Lazaro, J.; Herbin, H.; Jacquinet-Husson, N.; Payan, S.; Péquignot, E.; Pierangelo, C.; Sellitto, P.; Stubenrauch, C.

    2014-12-01

    Besides their strong contribution to weather forecast improvement through data assimilation, thermal infrared sounders onboard polar-orbiting platforms are now playing a key role for monitoring atmospheric composition changes. The Infrared Atmospheric Sounding Interferometer (IASI) instrument developed by the French space agency (CNES) and launched by EUMETSAT onboard the Metop satellite series is providing essential inputs for weather forecasting and pollution/climate monitoring owing to its smart combination of large horizontal swath, good spectral resolution and high radiometric performance. EUMETSAT is currently preparing the next polar-orbiting program (EPS-SG) with the Metop-SG satellite series that should be launched around 2020. In this framework, CNES is studying the concept of a new instrument, the IASI-New Generation (IASI-NG), characterized by an improvement of both spectral and radiometric characteristics as compared to IASI, with three objectives: (i) continuity of the IASI/Metop series; (ii) improvement of vertical resolution; and (iii) improvement of the accuracy and detection threshold for atmospheric and surface components. In this paper, we show that an improvement of spectral resolution and radiometric noise fulfil these objectives by leading to (i) a better vertical coverage in the lower part of the troposphere, thanks to the increase in spectral resolution; and (ii) an increase in the accuracy of the retrieval of several thermodynamic, climate and chemistry variables, thanks to the improved signal-to-noise ratio as well as less interference between the signatures of the absorbing species in the measured radiances. The detection limit of several atmospheric species is also improved. We conclude that IASI-NG has the potential to strongly benefit the numerical weather prediction, chemistry and climate communities now connected through the European GMES/Copernicus initiative.

  7. Towards IASI-New Generation (IASI-NG): impact of improved spectral resolution and radiometric noise on the retrieval of thermodynamic, chemistry and climate variables

    NASA Astrophysics Data System (ADS)

    Crevoisier, C.; Clerbaux, C.; Guidard, V.; Phulpin, T.; Armante, R.; Barret, B.; Camy-Peyret, C.; Chaboureau, J.-P.; Coheur, P.-F.; Crépeau, L.; Dufour, G.; Labonnote, L.; Lavanant, L.; Hadji-Lazaro, J.; Herbin, H.; Jacquinet-Husson, N.; Payan, S.; Péquignot, E.; Pierangelo, C.; Sellitto, P.; Stubenrauch, C.

    2013-12-01

    Besides their strong contribution to weather forecast improvement through data assimilation, thermal infrared sounders onboard polar-orbiting platforms are now playing a key role for monitoring atmospheric composition changes. The Infrared Atmospheric Sounding Interferometer (IASI) instrument developed by the French space agency (CNES) and launched by Eumetsat onboard the Metop satellite series is providing essential inputs for weather forecasting and pollution/climate monitoring owing to its smart combination of large horizontal swath, good spectral resolution and high radiometric performance. EUMETSAT is currently preparing the next polar-orbiting program (EPS-SG) with the Metop-SG satellite series that should be launched around 2020. In this framework, CNES is studying the concept of a new instrument, the IASI-New Generation (IASI-NG), characterized by an improvement of both spectral and radiometric characteristics as compared to IASI, with three objectives: (i) continuity of the IASI/Metop series; (ii) improvement of vertical resolution; (iii) improvement of the accuracy and detection threshold for atmospheric and surface components. In this paper, we show that an improvement of spectral resolution and radiometric noise fulfill these objectives by leading to (i) a better vertical coverage in the lower part of the troposphere, thanks to the increase in spectral resolution; (ii) an increase in the accuracy of the retrieval of several thermodynamic, climate and chemistry variables, thanks to the improved signal-to-noise ratio as well as less interferences between the signatures of the absorbing species in the measured radiances. The detection limit of several atmospheric species is also improved. We conclude that IASI-NG has the potential for strongly benefiting the numerical weather prediction, chemistry and climate communities now connected through the European GMES/Copernicus initiative.

  8. ROLE OF SPATIAL RESOLUTION AND SPECTRAL CONTENT IN CHANGE DETECTION.

    USGS Publications Warehouse

    Milazzo, Valerie A.

    1984-01-01

    Summary form only given, as follows. Advancements in remote sensing technology have brought improvements and sophistication to modern remote sensor systems, especially those aboard earth resources satellites. These improvements have considerbly expanded the capabilities of the newer sensor systems, particularly the capability to achieve greatly increased spatial and spectral resolution levels. The debate still lingers, however, over whether future systems should maximize spatial resolution or spectral information, or both. As yet, the high costs and large volumes of data associated with even modest incremental improvements in spatial and spectral content have precluded the design of a single system that attempts to fully optimize both. Thus, the user is faced with having to choose between those systems providing high spatial resolutions but limited spectral information and those which offer a broad range of spectral data but hold spatial resolution to a less than optimum level. In this study, the contribution of both spatial resolution and spectral content to land cover change detection is examined. Ten-meter SPOT simulation imagery is compared with multispectral images acquired by the Thematic Mapper sensor system for use in the visual interpretation and mapping of changes. Several image processing and enhancement techniques are utilized to maximize the spatial and spectral data content offered by each system. Results indicate that when using visual image interpretation techniques to detect change, higher spatial resolutions are generally preferred over increased spectral content.

  9. Broadband Radiometric LED Measurements

    PubMed Central

    Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

    2017-01-01

    At present, broadband radiometric measurements of LEDs with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed. PMID:28649167

  10. Broadband radiometric LED measurements

    NASA Astrophysics Data System (ADS)

    Eppeldauer, G. P.; Cooksey, C. C.; Yoon, H. W.; Hanssen, L. M.; Podobedov, V. B.; Vest, R. E.; Arp, U.; Miller, C. C.

    2016-09-01

    At present, broadband radiometric LED measurements with uniform and low-uncertainty results are not available. Currently, either complicated and expensive spectral radiometric measurements or broadband photometric LED measurements are used. The broadband photometric measurements are based on the CIE standardized V(λ) function, which cannot be used in the UV range and leads to large errors when blue or red LEDs are measured in its wings, where the realization is always poor. Reference irradiance meters with spectrally constant response and high-intensity LED irradiance sources were developed here to implement the previously suggested broadband radiometric LED measurement procedure [1, 2]. Using a detector with spectrally constant response, the broadband radiometric quantities of any LEDs or LED groups can be simply measured with low uncertainty without using any source standard. The spectral flatness of filtered-Si detectors and low-noise pyroelectric radiometers are compared. Examples are given for integrated irradiance measurement of UV and blue LED sources using the here introduced reference (standard) pyroelectric irradiance meters. For validation, the broadband measured integrated irradiance of several LED-365 sources were compared with the spectrally determined integrated irradiance derived from an FEL spectral irradiance lamp-standard. Integrated responsivity transfer from the reference irradiance meter to transfer standard and field UV irradiance meters is discussed.

  11. A spatial-temporal-spectral blending model using satellite images

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Fu, D.; Sun, X.; Chen, H.; She, X.

    2016-04-01

    Due to the budget and technical limitations, remote sensing sensor designs trade spatial resolution, swath width and spectral resolution. Consequently, no sensor can provide high spatial resolution, high temporal resolution and high spectral resolution simultaneously. However, the ability of Earth observation at fine resolution is urgently needed for global change science. One possible solution is to “blend” the reflectance from a variety of satellite data sources, including those providing high spatial resolution and less frequent coverage (e.g., Landsat Thematic Mapper, TM), daily global data (e.g., Moderate Resolution Imaging Spectroradiometer, MODIS), and high spectral resolution and infrequent revisit cycle (e.g., Hyperion). However, the previous algorithms for blending multi-source remotely sensed data have some shortcomings, especially with regard to hyperspectral information. This study has developed a SPAtial-Temporal-Spectral blending model (SPATS) that can simulate surface reflectance with high spatial-temporal-spectral resolution. SPATS is based on an existing spatial-temporal image blending model and a spatial-spectral image blending model. The performance of SPATS was tested with both simulated and observed satellite data, using Landsat TM, Hyperion and MODIS data, as well as heterogeneous landscapes as examples. The results show that the high spatial-temporal-spectral resolution reflectance data can be applied to investigations of global landscapes that are changing at different temporal scales.

  12. Spectral DAISY: a combined target spatial-spectral dense feature descriptor for improved tracking performance

    NASA Astrophysics Data System (ADS)

    Weinheimer, Jeffrey J.; Villeneuve, Pierre; Beaven, Scott G.

    2011-09-01

    In EO tracking, target spatial and spectral features can be used to improve performance since they help distinguish the targets from each other when confusion occurs during normal kinematic tracking. In this paper we introduce a method to encode a target's descriptive spatial information into a multi-dimensional signature vector, allowing us to convert the problem of spatial template matching into a form similar to spectral signature matching. This allows us to leverage multivariate algorithms commonly used with hyperspectral data to the problem of exploiting panchromatic imagery. We show how this spatial signature formulation naturally leads to a hybrid spatial-spectral descriptor vector that supports exploitation using commonly-used spectral algorithms. We introduce a new descriptor called Spectral DAISY for encoding spatial information into a signature vector, based on the concept of the DAISY dense descriptor. We demonstrate the process on real data and show how the combined spatial/spectral feature can be used to improve target/track association over spectral or spatial features alone.

  13. Advances in Spectral-Spatial Classification of Hyperspectral Images

    NASA Technical Reports Server (NTRS)

    Fauvel, Mathieu; Tarabalka, Yuliya; Benediktsson, Jon Atli; Chanussot, Jocelyn; Tilton, James C.

    2012-01-01

    Recent advances in spectral-spatial classification of hyperspectral images are presented in this paper. Several techniques are investigated for combining both spatial and spectral information. Spatial information is extracted at the object (set of pixels) level rather than at the conventional pixel level. Mathematical morphology is first used to derive the morphological profile of the image, which includes characteristics about the size, orientation and contrast of the spatial structures present in the image. Then the morphological neighborhood is defined and used to derive additional features for classification. Classification is performed with support vector machines using the available spectral information and the extracted spatial information. Spatial post-processing is next investigated to build more homogeneous and spatially consistent thematic maps. To that end, three presegmentation techniques are applied to define regions that are used to regularize the preliminary pixel-wise thematic map. Finally, a multiple classifier system is defined to produce relevant markers that are exploited to segment the hyperspectral image with the minimum spanning forest algorithm. Experimental results conducted on three real hyperspectral images with different spatial and spectral resolutions and corresponding to various contexts are presented. They highlight the importance of spectral-spatial strategies for the accurate classification of hyperspectral images and validate the proposed methods.

  14. Advances in Spectral-Spatial Classification of Hyperspectral Images

    NASA Technical Reports Server (NTRS)

    Fauvel, Mathieu; Tarabalka, Yuliya; Benediktsson, Jon Atli; Chanussot, Jocelyn; Tilton, James C.

    2012-01-01

    Recent advances in spectral-spatial classification of hyperspectral images are presented in this paper. Several techniques are investigated for combining both spatial and spectral information. Spatial information is extracted at the object (set of pixels) level rather than at the conventional pixel level. Mathematical morphology is first used to derive the morphological profile of the image, which includes characteristics about the size, orientation and contrast of the spatial structures present in the image. Then the morphological neighborhood is defined and used to derive additional features for classification. Classification is performed with support vector machines using the available spectral information and the extracted spatial information. Spatial post-processing is next investigated to build more homogeneous and spatially consistent thematic maps. To that end, three presegmentation techniques are applied to define regions that are used to regularize the preliminary pixel-wise thematic map. Finally, a multiple classifier system is defined to produce relevant markers that are exploited to segment the hyperspectral image with the minimum spanning forest algorithm. Experimental results conducted on three real hyperspectral images with different spatial and spectral resolutions and corresponding to various contexts are presented. They highlight the importance of spectral-spatial strategies for the accurate classification of hyperspectral images and validate the proposed methods.

  15. Advances in Spectral-Spatial Classification of Hyperspectral Images

    NASA Technical Reports Server (NTRS)

    Fauvel, Mathieu; Tarabalka, Yuliya; Benediktsson, Jon Atli; Chanussot, Jocelyn; Tilton, James C.

    2012-01-01

    Recent advances in spectral-spatial classification of hyperspectral images are presented in this paper. Several techniques are investigated for combining both spatial and spectral information. Spatial information is extracted at the object (set of pixels) level rather than at the conventional pixel level. Mathematical morphology is first used to derive the morphological profile of the image, which includes characteristics about the size, orientation, and contrast of the spatial structures present in the image. Then, the morphological neighborhood is defined and used to derive additional features for classification. Classification is performed with support vector machines (SVMs) using the available spectral information and the extracted spatial information. Spatial postprocessing is next investigated to build more homogeneous and spatially consistent thematic maps. To that end, three presegmentation techniques are applied to define regions that are used to regularize the preliminary pixel-wise thematic map. Finally, a multiple-classifier (MC) system is defined to produce relevant markers that are exploited to segment the hyperspectral image with the minimum spanning forest algorithm. Experimental results conducted on three real hyperspectral images with different spatial and spectral resolutions and corresponding to various contexts are presented. They highlight the importance of spectral–spatial strategies for the accurate classification of hyperspectral images and validate the proposed methods.

  16. Evaluation of AMOEBA: a spectral-spatial classification method

    USGS Publications Warehouse

    Jenson, Susan K.; Loveland, Thomas R.; Bryant, J.

    1982-01-01

    Muitispectral remotely sensed images have been treated as arbitrary multivariate spectral data for purposes of clustering and classifying. However, the spatial properties of image data can also be exploited. AMOEBA is a clustering and classification method that is based on a spatially derived model for image data. In an evaluation test, Landsat data were classified with both AMOEBA and a widely used spectral classifier. The test showed that irrigated crop types can be classified as accurately with the AMOEBA method as with the generally used spectral method ISOCLS; the AMOEBA method, however, requires less computer time.

  17. Theory of spatially and spectrally partially coherent pulses.

    PubMed

    Lajunen, Hanna; Vahimaa, Pasi; Tervo, Jani

    2005-08-01

    A coherent-mode representation for spatially and spectrally partially coherent pulses is derived both in the space-frequency domain and in the space-time domain. It is shown that both the cross-spectral density and the mutual coherence function of partially coherent pulses can be expressed as a sum of spatially and spectrally and temporally completely coherent modes. The concept of the effective degree of coherence for nonstationary fields is introduced. As an application of the theory, the propagation of Gaussian Schell-model pulsed beams in the space-frequency domain is considered and their coherent-mode representation is presented.

  18. Radiometric Calibration Assessment of Commercial High Spatial Resolution Multispectral Image Products

    NASA Technical Reports Server (NTRS)

    Thome, Kurt; Leisso, Nathan; Buchanan, John

    2007-01-01

    This paper describes the results of commercial high spatial resolution sensors. The topics include: 1) Reflectance-based approach; 2) U of A test sites; 3) Test Site Selection; 4) Resort Living; 5) Aerosol parameters; 6) Surface reflectance retrieval; 7) Accuracy/precision; 8) Data sets; 9) June 23, 2005 for Ikonos; 10) QuickBird Results; 11) Ikonos results; 12) Orbview results; 13) Ikonos redux; and 14) Overall results.

  19. An upper-bound metric for characterizing spectral and spatial coregistration errors in spectral imaging.

    PubMed

    Skauli, Torbjørn

    2012-01-16

    Coregistration errors in multi- and hyperspectral imaging sensors arise when the spatial sensitivity pattern differs between bands or when the spectral response varies across the field of view, potentially leading to large errors in the recorded image data. In imaging spectrometers, spectral and spatial offset errors are customarily specified as "smile" and "keystone" distortions. However these characteristics do not account for errors resulting from variations in point spread function shape or spectral bandwidth. This paper proposes improved metrics for coregistration error both in the spatial and spectral dimensions. The metrics are essentially the integrated difference between point spread functions. It is shown that these metrics correspond to an upper bound on the error in image data. The metrics enable estimation of actual data errors for a given image, and can be used as part of the merit function in optical design optimization, as well as for benchmarking of spectral image sensors.

  20. Digital phantoms generated by spectral and spatial light modulators

    PubMed Central

    Chon, Bonghwan; Tokumasu, Fuyuki; Lee, Ji Youn; Allen, David W.; Rice, Joseph P.; Hwang, Jeeseong

    2015-01-01

    Abstract. A hyperspectral image projector (HIP) based on liquid crystal on silicon spatial light modulators is explained and demonstrated to generate data cubes. The HIP-constructed data cubes are three-dimensional images of the spatial distribution of spectrally resolved abundances of intracellular light-absorbing oxyhemoglobin molecules in single erythrocytes. Spectrally and spatially resolved image data indistinguishable from the real scene may be used as standard data cubes, so-called digital phantoms, to calibrate image sensors and validate image analysis algorithms for their measurement quality, performance consistency, and interlaboratory comparisons for quantitative biomedical imaging applications. PMID:26502383

  1. Digital phantoms generated by spectral and spatial light modulators

    NASA Astrophysics Data System (ADS)

    Chon, Bonghwan; Tokumasu, Fuyuki; Lee, Ji Youn; Allen, David W.; Rice, Joseph P.; Hwang, Jeeseong

    2015-12-01

    A hyperspectral image projector (HIP) based on liquid crystal on silicon spatial light modulators is explained and demonstrated to generate data cubes. The HIP-constructed data cubes are three-dimensional images of the spatial distribution of spectrally resolved abundances of intracellular light-absorbing oxyhemoglobin molecules in single erythrocytes. Spectrally and spatially resolved image data indistinguishable from the real scene may be used as standard data cubes, so-called digital phantoms, to calibrate image sensors and validate image analysis algorithms for their measurement quality, performance consistency, and interlaboratory comparisons for quantitative biomedical imaging applications.

  2. Performance analysis of improved methodology for incorporation of spatial/spectral variability in synthetic hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Scanlan, Neil W.; Schott, John R.; Brown, Scott D.

    2004-01-01

    measures used in this study will in combination attempt to determine which texture characterization models best capture the correct statistical and radiometric attributes of the corresponding real image textures in both the spatial and spectral domains. The motivation for this work is to refine our understanding of the complexities of texture phenomena so that an optimal texture characterization model that can accurately account for these complexities can be eventually implemented into a synthetic image generation (SIG) model. Further, conclusions will be drawn regarding which of the candidate texture models are able to achieve realistic levels of spatial and spectral clutter, thereby permitting more effective and robust testing of hyperspectral algorithms in synthetic imagery.

  3. Performance analysis of improved methodology for incorporation of spatial/spectral variability in synthetic hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Scanlan, Neil W.; Schott, John R.; Brown, Scott D.

    2003-12-01

    measures used in this study will in combination attempt to determine which texture characterization models best capture the correct statistical and radiometric attributes of the corresponding real image textures in both the spatial and spectral domains. The motivation for this work is to refine our understanding of the complexities of texture phenomena so that an optimal texture characterization model that can accurately account for these complexities can be eventually implemented into a synthetic image generation (SIG) model. Further, conclusions will be drawn regarding which of the candidate texture models are able to achieve realistic levels of spatial and spectral clutter, thereby permitting more effective and robust testing of hyperspectral algorithms in synthetic imagery.

  4. Multiple Spectral-Spatial Classification Approach for Hyperspectral Data

    NASA Technical Reports Server (NTRS)

    Tarabalka, Yuliya; Benediktsson, Jon Atli; Chanussot, Jocelyn; Tilton, James C.

    2010-01-01

    A .new multiple classifier approach for spectral-spatial classification of hyperspectral images is proposed. Several classifiers are used independently to classify an image. For every pixel, if all the classifiers have assigned this pixel to the same class, the pixel is kept as a marker, i.e., a seed of the spatial region, with the corresponding class label. We propose to use spectral-spatial classifiers at the preliminary step of the marker selection procedure, each of them combining the results of a pixel-wise classification and a segmentation map. Different segmentation methods based on dissimilar principles lead to different classification results. Furthermore, a minimum spanning forest is built, where each tree is rooted on a classification -driven marker and forms a region in the spectral -spatial classification: map. Experimental results are presented for two hyperspectral airborne images. The proposed method significantly improves classification accuracies, when compared to previously proposed classification techniques.

  5. Evaluation of spatial, radiometric and spectral thematic mapper performance for coastal studies

    NASA Technical Reports Server (NTRS)

    Klemas, V.

    1983-01-01

    Radiative transfer theory was used to model upwelling radiance for an orbiting sensor viewing an estuarine environment. Radiance was calculated in Tm bands 3,4, and 5 and MSS bands 4 and 5 for an optically shallow estuary of either clear or turbid water, and of three bottom types: vegetation, sand, or mud. A portion of a TM image of Chesapeake Bay was enhanced to obtain a quick look at what submerged features could be detected. The enhancements were compared with low altitude color aerial photography. The TM bands 1,2, and 3 were found to contain water and submerged features information. Band 1 contained a significant amount of noise and low contrast. Band 2 appeared to contain the most amount of bottom information. Band 3, while having the least amount of noise and best constrast, contained a lesser amount of bottom information because of increase water absorption. Several water signatures were identified which correlated with submerged vegetation shown in the aerial photography.

  6. Comparison of Spectral-Only and Spectral/Spatial Face Recognition for Personal Identity Verification

    NASA Astrophysics Data System (ADS)

    Pan, Zhihong; Healey, Glenn; Tromberg, Bruce

    2009-12-01

    Face recognition based on spatial features has been widely used for personal identity verification for security-related applications. Recently, near-infrared spectral reflectance properties of local facial regions have been shown to be sufficient discriminants for accurate face recognition. In this paper, we compare the performance of the spectral method with face recognition using the eigenface method on single-band images extracted from the same hyperspectral image set. We also consider methods that use multiple original and PCA-transformed bands. Lastly, an innovative spectral eigenface method which uses both spatial and spectral features is proposed to improve the quality of the spectral features and to reduce the expense of the computation. The algorithms are compared using a consistent framework.

  7. The spectral signature of cloud spatial structure in shortwave irradiance

    PubMed Central

    Song, Shi; Schmidt, K. Sebastian; Pilewskie, Peter; King, Michael D.; Heidinger, Andrew K.; Walther, Andi; Iwabuchi, Hironobu; Wind, Gala; Coddington, Odele M.

    2017-01-01

    In this paper, we used cloud imagery from a NASA field experiment in conjunction with three-dimensional radiative transfer calculations to show that cloud spatial structure manifests itself as a spectral signature in shortwave irradiance fields – specifically in transmittance and net horizontal photon transport in the visible and near-ultraviolet wavelength range. We found a robust correlation between the magnitude of net horizontal photon transport (H) and its spectral dependence (slope), which is scale-invariant and holds for the entire pixel population of a domain. This was surprising at first given the large degree of spatial inhomogeneity. We prove that the underlying physical mechanism for this phenomenon is molecular scattering in conjunction with cloud spatial structure. On this basis, we developed a simple parameterization through a single parameter ε, which quantifies the characteristic spectral signature of spatial inhomogeneities. In the case we studied, neglecting net horizontal photon transport leads to a local transmittance bias of ±12–19 %, even at the relatively coarse spatial resolution of 20 km. Since three-dimensional effects depend on the spatial context of a given pixel in a nontrivial way, the spectral dimension of this problem may emerge as the starting point for future bias corrections. PMID:28824698

  8. Spectral-spatial classification to pattern recognition of hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Su, Tung-Ching

    2012-04-01

    Recently several spectral-spatial classification methods had been presented and applied to pattern recognition of hyperspectral imagery. However, the present methods are especially suitable for classifying images with large spatial structures in spite of the derived classification accuracies of above 90%. To classify hyperspectral images with larger as well as smaller spatial structures, a novel spectral-spatial classification method was presented and tested on an Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) image with 145×145 pixels and 220 bands. Firstly, the AVIRIS image was implemented a spectral mixture analysis using minimum noise fraction (MNF). Based on the obtained n-dimensional eigenimage, support vector machine (SVM) was used to classify the AVIRIS image. Simultaneously, the eigenimage was calculated the mathematical morphology-based image gradients for the n dimensions so to obtain n watershed segmentation images. Finally, the SVM classification map was turned into several new ones through a series of post-processing. The experimental results verify that the proposed spectral-spatial classification method has the capability to detect larger as well as smaller spatial structures in hyperspectral imagery.

  9. The spectral signature of cloud spatial structure in shortwave irradiance.

    PubMed

    Song, Shi; Schmidt, K Sebastian; Pilewskie, Peter; King, Michael D; Heidinger, Andrew K; Walther, Andi; Iwabuchi, Hironobu; Wind, Gala; Coddington, Odele M

    2016-11-08

    In this paper, we used cloud imagery from a NASA field experiment in conjunction with three-dimensional radiative transfer calculations to show that cloud spatial structure manifests itself as a spectral signature in shortwave irradiance fields - specifically in transmittance and net horizontal photon transport in the visible and near-ultraviolet wavelength range. We found a robust correlation between the magnitude of net horizontal photon transport (H) and its spectral dependence (slope), which is scale-invariant and holds for the entire pixel population of a domain. This was surprising at first given the large degree of spatial inhomogeneity. We prove that the underlying physical mechanism for this phenomenon is molecular scattering in conjunction with cloud spatial structure. On this basis, we developed a simple parameterization through a single parameter ε, which quantifies the characteristic spectral signature of spatial inhomogeneities. In the case we studied, neglecting net horizontal photon transport leads to a local transmittance bias of ±12-19 %, even at the relatively coarse spatial resolution of 20 km. Since three-dimensional effects depend on the spatial context of a given pixel in a nontrivial way, the spectral dimension of this problem may emerge as the starting point for future bias corrections.

  10. Anticipating HESSI's Spatially Resolved View of Spectral Evolution

    NASA Technical Reports Server (NTRS)

    Newton, Elizabeth K.; Giblin, Timothy; Tom, Metcalf

    2000-01-01

    The spectral evolution of observed flares' hard X-ray emission is found to conform to certain patterns in color-color diagrams. By combining the spectral resolution of BATSE data with the spatial resolution of HXT data, we are able to address the nature of flare energy release and anticipate what kind of observations HESSI may make of the energy release/particle acceleration site in flares.

  11. Spatial-spectral method for classification of hyperspectral images.

    PubMed

    Bian, Xiaoyong; Zhang, Tianxu; Yan, Luxin; Zhang, Xiaolong; Fang, Houzhang; Liu, Hai

    2013-03-15

    Spatial-spectral approach with spatially adaptive classification of hyperspectral images is proposed. The rotation-invariant spatial texture information for each object is exploited and incorporated into the classifier by using the modified local Gabor binary pattern to distinguish different types of classes of interest. The proposed method can effectively suppress anisotropic texture in spatially separate classes as well as improve the discrimination among classes. Moreover, it becomes more robust with the within-class variation. Experimental results on the classification of three real hyperspectral remote sensing images demonstrate the effectiveness of the proposed approach.

  12. Methods for spectral image analysis by exploiting spatial simplicity

    DOEpatents

    Keenan, Michael R.

    2010-05-25

    Several full-spectrum imaging techniques have been introduced in recent years that promise to provide rapid and comprehensive chemical characterization of complex samples. One of the remaining obstacles to adopting these techniques for routine use is the difficulty of reducing the vast quantities of raw spectral data to meaningful chemical information. Multivariate factor analysis techniques, such as Principal Component Analysis and Alternating Least Squares-based Multivariate Curve Resolution, have proven effective for extracting the essential chemical information from high dimensional spectral image data sets into a limited number of components that describe the spectral characteristics and spatial distributions of the chemical species comprising the sample. There are many cases, however, in which those constraints are not effective and where alternative approaches may provide new analytical insights. For many cases of practical importance, imaged samples are "simple" in the sense that they consist of relatively discrete chemical phases. That is, at any given location, only one or a few of the chemical species comprising the entire sample have non-zero concentrations. The methods of spectral image analysis of the present invention exploit this simplicity in the spatial domain to make the resulting factor models more realistic. Therefore, more physically accurate and interpretable spectral and abundance components can be extracted from spectral images that have spatially simple structure.

  13. Methods for spectral image analysis by exploiting spatial simplicity

    DOEpatents

    Keenan, Michael R.

    2010-11-23

    Several full-spectrum imaging techniques have been introduced in recent years that promise to provide rapid and comprehensive chemical characterization of complex samples. One of the remaining obstacles to adopting these techniques for routine use is the difficulty of reducing the vast quantities of raw spectral data to meaningful chemical information. Multivariate factor analysis techniques, such as Principal Component Analysis and Alternating Least Squares-based Multivariate Curve Resolution, have proven effective for extracting the essential chemical information from high dimensional spectral image data sets into a limited number of components that describe the spectral characteristics and spatial distributions of the chemical species comprising the sample. There are many cases, however, in which those constraints are not effective and where alternative approaches may provide new analytical insights. For many cases of practical importance, imaged samples are "simple" in the sense that they consist of relatively discrete chemical phases. That is, at any given location, only one or a few of the chemical species comprising the entire sample have non-zero concentrations. The methods of spectral image analysis of the present invention exploit this simplicity in the spatial domain to make the resulting factor models more realistic. Therefore, more physically accurate and interpretable spectral and abundance components can be extracted from spectral images that have spatially simple structure.

  14. Spatial and spectral effects in subcritical system pulsed experiments

    SciTech Connect

    Dulla, S.; Nervo, M.; Ravetto, P.; Carta, M.

    2013-07-01

    Accurate neutronic models are needed for the interpretation of pulsed experiments in subcritical systems. In this work, the extent of spatial and spectral effects in the pulse propagation phenomena is investigated and the analysis is applied to the GUINEVERE experiment. The multigroup cross section data is generated by the Monte Carlo SERPENT code and the neutronic evolution following the source pulse is simulated by a kinetic diffusion code. The results presented show that important spatial and spectral aspects need to be properly accounted for and that a detailed energy approach may be needed to adequately capture the physical features of the system to the pulse injection. (authors)

  15. Passive Standoff Super Resolution Imaging using Spatial-Spectral Multiplexing

    DTIC Science & Technology

    2017-08-14

    transform variable of OPD in cycles per unit length, and the constant term from Eq. (89) has been removed for clarity. The full width spectral resolution...an average spatial period of 145.8 μm, which corresponds to an average spatial frequency of fc = 6.87 cycles /mm across the SLM. This carrier was...an average frequency of fc = 6.87 cycles /mm, was modulated with randomly generated envelopes. Random angular spectra were generated in MATLAB as

  16. Spatial, Temporal and Spectral Satellite Image Fusion via Sparse Representation

    NASA Astrophysics Data System (ADS)

    Song, Huihui

    Remote sensing provides good measurements for monitoring and further analyzing the climate change, dynamics of ecosystem, and human activities in global or regional scales. Over the past two decades, the number of launched satellite sensors has been increasing with the development of aerospace technologies and the growing requirements on remote sensing data in a vast amount of application fields. However, a key technological challenge confronting these sensors is that they tradeoff between spatial resolution and other properties, including temporal resolution, spectral resolution, swath width, etc., due to the limitations of hardware technology and budget constraints. To increase the spatial resolution of data with other good properties, one possible cost-effective solution is to explore data integration methods that can fuse multi-resolution data from multiple sensors, thereby enhancing the application capabilities of available remote sensing data. In this thesis, we propose to fuse the spatial resolution with temporal resolution and spectral resolution, respectively, based on sparse representation theory. Taking the study case of Landsat ETM+ (with spatial resolution of 30m and temporal resolution of 16 days) and MODIS (with spatial resolution of 250m ~ 1km and daily temporal resolution) reflectance, we propose two spatial-temporal fusion methods to combine the fine spatial information of Landsat image and the daily temporal resolution of MODIS image. Motivated by that the images from these two sensors are comparable on corresponding bands, we propose to link their spatial information on available Landsat- MODIS image pair (captured on prior date) and then predict the Landsat image from the MODIS counterpart on prediction date. To well-learn the spatial details from the prior images, we use a redundant dictionary to extract the basic representation atoms for both Landsat and MODIS images based on sparse representation. Under the scenario of two prior Landsat

  17. Spatial and spectral performance of a chromotomosynthetic hyperspectral imaging system

    NASA Astrophysics Data System (ADS)

    Bostick, Randall L.; Perram, Glen P.

    2012-03-01

    The spatial and spectral resolutions achievable by a prototype rotating prism chromotomosynthetic imaging (CTI) system operating in the visible spectrum are described. The instrument creates hyperspectral imagery by collecting a set of 2D images with each spectrally projected at a different rotation angle of the prism. Mathematical reconstruction techniques that have been well tested in the field of medical physics are used to reconstruct the data to produce the 3D hyperspectral image. The instrument operates with a 100 mm focusing lens in the spectral range of 400-900 nm with a field of view of 71.6 mrad and angular resolution of 0.8-1.6 μrad. The spectral resolution is 0.6 nm at the shortest wavelengths, degrading to over 10 nm at the longest wavelengths. Measurements using a point-like target show that performance is limited by chromatic aberration. The system model is slightly inaccurate due to poor estimation of detector spatial resolution, this is corrected based on results improving model performance. As with traditional dispersion technology, calibration of the transformed wavelength axis is required, though with this technology calibration improves both spectral and spatial resolution. While this prototype does not operate at high speeds, components exist which will allow for CTI systems to generate hyperspectral video imagery at rates greater than 100 Hz.

  18. Radiometric consistency assessment of hyperspectral infrared sounders

    NASA Astrophysics Data System (ADS)

    Wang, L.; Han, Y.; Jin, X.; Chen, Y.; Tremblay, D. A.

    2015-07-01

    The radiometric and spectral consistency among the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) is fundamental for the creation of long-term infrared (IR) hyperspectral radiance benchmark datasets for both inter-calibration and climate-related studies. In this study, the CrIS radiance measurements on Suomi National Polar-orbiting Partnership (SNPP) satellite are directly compared with IASI on MetOp-A and -B at the finest spectral scale and with AIRS on Aqua in 25 selected spectral regions through one year of simultaneous nadir overpass (SNO) observations to evaluate radiometric consistency of these four hyperspectral IR sounders. The spectra from different sounders are paired together through strict spatial and temporal collocation. The uniform scenes are selected by examining the collocated Visible Infrared Imaging Radiometer Suite (VIIRS) pixels. Their brightness temperature (BT) differences are then calculated by converting the spectra onto common spectral grids. The results indicate that CrIS agrees well with IASI on MetOp-A and IASI on MetOp-B at the longwave IR (LWIR) and middle-wave IR (MWIR) bands with 0.1-0.2 K differences. There are no apparent scene-dependent patterns for BT differences between CrIS and IASI for individual spectral channels. CrIS and AIRS are compared at the 25 spectral regions for both Polar and Tropical SNOs. The combined global SNO datasets indicate that, the CrIS-AIRS BT differences are less than or around 0.1 K among 21 of 25 comparison spectral regions and they range from 0.15 to 0.21 K in the remaining 4 spectral regions. CrIS-AIRS BT differences in some comparison spectral regions show weak scene-dependent features.

  19. Radiometric consistency assessment of hyperspectral infrared sounders

    NASA Astrophysics Data System (ADS)

    Wang, L.; Han, Y.; Jin, X.; Chen, Y.; Tremblay, D. A.

    2015-11-01

    The radiometric and spectral consistency among the Atmospheric Infrared Sounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), and the Cross-track Infrared Sounder (CrIS) is fundamental for the creation of long-term infrared (IR) hyperspectral radiance benchmark data sets for both intercalibration and climate-related studies. In this study, the CrIS radiance measurements on Suomi National Polar-orbiting Partnership (SNPP) satellite are directly compared with IASI on MetOp-A and MetOp-B at the finest spectral scale and with AIRS on Aqua in 25 selected spectral regions through simultaneous nadir overpass (SNO) observations in 2013, to evaluate radiometric consistency of these four hyperspectral IR sounders. The spectra from different sounders are paired together through strict spatial and temporal collocation. The uniform scenes are selected by examining the collocated Visible Infrared Imaging Radiometer Suite (VIIRS) pixels. Their brightness temperature (BT) differences are then calculated by converting the spectra onto common spectral grids. The results indicate that CrIS agrees well with IASI on MetOp-A and IASI on MetOp-B at the long-wave IR (LWIR) and middle-wave IR (MWIR) bands with 0.1-0.2 K differences. There are no apparent scene-dependent patterns for BT differences between CrIS and IASI for individual spectral channels. CrIS and AIRS are compared at the 25 spectral regions for both polar and tropical SNOs. The combined global SNO data sets indicate that the CrIS-AIRS BT differences are less than or around 0.1 K among 21 of 25 spectral regions and they range from 0.15 to 0.21 K in the remaining four spectral regions. CrIS-AIRS BT differences in some comparison spectral regions show weak scene-dependent features.

  20. The Spectral Signature of Cloud Spatial Structure in Shortwave Radiation

    NASA Astrophysics Data System (ADS)

    Song, Shi

    In this thesis, we aim to systematically understand the relationship between cloud spatial structure and its radiation imprints, i.e., three-dimensional (3D) cloud effects, with the ultimate goal of deriving accurate radiative energy budget estimates from space, aircraft, or ground-based observations under spatially inhomogeneous conditions. By studying the full spectral information in the measured and modeled shortwave radiation fields of heterogeneous cloud scenes sampled during aircraft field experiments, we find evidence that cloud spatial structure reveals itself through spectral signatures in the associated irradiance and radiance fields in the near-ultraviolet and visible spectral range. The spectral signature of 3D cloud effects in irradiances is apparent as a domain- wide, consistent correlation between the magnitude and spectral dependence of net horizontal photon transport. The physical mechanism of this phenomenon is molecular scattering in conjunction with cloud heterogeneity. A simple parameterization with a single parameter epsilon is developed, which holds for individual pixels and the domain as a whole. We then investigate the impact of scene parameters on the discovered correlation and find that it is upheld for a wide range of scene conditions, although the value of epsilon varies from scene to scene. The spectral signature of 3D cloud effects in radiances manifests itself as a distinct relationship between the magnitude and spectral dependence of reflectance, which cannot be reproduced in the one-dimensional (1D) radiative transfer framework. Using the spectral signature in radiances and irradiances, it is possible to infer information on net horizontal photon transport from spectral radiance perturbations on the basis of pixel populations in sub-domains of a cloud scene. We show that two different biases need to be considered when attempting radiative closure between measured and modeled irradiance fields below inhomogeneous cloud fields: the

  1. A spatially adaptive spectral re-ordering technique for lossless coding of hyper-spectral images

    NASA Technical Reports Server (NTRS)

    Memon, Nasir D.; Galatsanos, Nikolas

    1995-01-01

    In this paper, we propose a new approach, applicable to lossless compression of hyper-spectral images, that alleviates some limitations of linear prediction as applied to this problem. According to this approach, an adaptive re-ordering of the spectral components of each pixel is performed prior to prediction and encoding. This re-ordering adaptively exploits, on a pixel-by pixel basis, the presence of inter-band correlations for prediction. Furthermore, the proposed approach takes advantage of spatial correlations, and does not introduce any coding overhead to transmit the order of the spectral bands. This is accomplished by using the assumption that two spatially adjacent pixels are expected to have similar spectral relationships. We thus have a simple technique to exploit spectral and spatial correlations in hyper-spectral data sets, leading to compression performance improvements as compared to our previously reported techniques for lossless compression. We also look at some simple error modeling techniques for further exploiting any structure that remains in the prediction residuals prior to entropy coding.

  2. Spatial-spectral preprocessing for endmember extraction on GPU's

    NASA Astrophysics Data System (ADS)

    Jimenez, Luis I.; Plaza, Javier; Plaza, Antonio; Li, Jun

    2016-10-01

    Spectral unmixing is focused in the identification of spectrally pure signatures, called endmembers, and their corresponding abundances in each pixel of a hyperspectral image. Mainly focused on the spectral information contained in the hyperspectral images, endmember extraction techniques have recently included spatial information to achieve more accurate results. Several algorithms have been developed for automatic or semi-automatic identification of endmembers using spatial and spectral information, including the spectral-spatial endmember extraction (SSEE) where, within a preprocessing step in the technique, both sources of information are extracted from the hyperspectral image and equally used for this purpose. Previous works have implemented the SSEE technique in four main steps: 1) local eigenvectors calculation in each sub-region in which the original hyperspectral image is divided; 2) computation of the maxima and minima projection of all eigenvectors over the entire hyperspectral image in order to obtain a candidates pixels set; 3) expansion and averaging of the signatures of the candidate set; 4) ranking based on the spectral angle distance (SAD). The result of this method is a list of candidate signatures from which the endmembers can be extracted using various spectral-based techniques, such as orthogonal subspace projection (OSP), vertex component analysis (VCA) or N-FINDR. Considering the large volume of data and the complexity of the calculations, there is a need for efficient implementations. Latest- generation hardware accelerators such as commodity graphics processing units (GPUs) offer a good chance for improving the computational performance in this context. In this paper, we develop two different implementations of the SSEE algorithm using GPUs. Both are based on the eigenvectors computation within each sub-region of the first step, one using the singular value decomposition (SVD) and another one using principal component analysis (PCA). Based

  3. Assessing spatial and seasonal variations in grasslands with spectral reflectances from a helicopter platform

    SciTech Connect

    Walthall, C.L. ); Middleton, E.M. )

    1992-11-30

    This work is part of the First International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment (FIFE), an international land-surface-atmosphere experiment aimed at improving the way climate models represent energy, water, heat, and carbon exchanges, and improving the utilization of satellite based remote sensing to monitor such parameters. The authors present radiometric measurements taken from a helicopter based platform. This base was chosen to serve as a platform at a height between the surface based instruments and the aircraft borne instruments. It is close enough to the ground to provide detailed spatial and spectral measurements comparable to the ground based systems, and can sample many sites in a two hour flight plan. The helicopter carried an eight channel modular multiband radiometer (MMR), video, and still camera. Data was analyzed for five separate sites on four seasonally different dates to get a measure of seasonal and spatial variation. Data from all eight channels was looked at, and compared with linear models which describe simple ratio (SR) and normalized difference vegetation index (NDVI) in terms of different surface variables.

  4. Spectral-spatial hyperspectral image classification using super-pixel-based spatial pyramid representation

    NASA Astrophysics Data System (ADS)

    Fan, Jiayuan; Tan, Hui Li; Toomik, Maria; Lu, Shijian

    2016-10-01

    Spatial pyramid matching has demonstrated its power for image recognition task by pooling features from spatially increasingly fine sub-regions. Motivated by the concept of feature pooling at multiple pyramid levels, we propose a novel spectral-spatial hyperspectral image classification approach using superpixel-based spatial pyramid representation. This technique first generates multiple superpixel maps by decreasing the superpixel number gradually along with the increased spatial regions for labelled samples. By using every superpixel map, sparse representation of pixels within every spatial region is then computed through local max pooling. Finally, features learned from training samples are aggregated and trained by a support vector machine (SVM) classifier. The proposed spectral-spatial hyperspectral image classification technique has been evaluated on two public hyperspectral datasets, including the Indian Pines image containing 16 different agricultural scene categories with a 20m resolution acquired by AVIRIS and the University of Pavia image containing 9 land-use categories with a 1.3m spatial resolution acquired by the ROSIS-03 sensor. Experimental results show significantly improved performance compared with the state-of-the-art works. The major contributions of this proposed technique include (1) a new spectral-spatial classification approach to generate feature representation for hyperspectral image, (2) a complementary yet effective feature pooling approach, i.e. the superpixel-based spatial pyramid representation that is used for the spatial correlation study, (3) evaluation on two public hyperspectral image datasets with superior image classification performance.

  5. Impervious surface extraction using coupled spectral-spatial features

    NASA Astrophysics Data System (ADS)

    Yu, Xinju; Shen, Zhanfeng; Cheng, Xi; Xia, Liegang; Luo, Jiancheng

    2016-07-01

    Accurate extraction of urban impervious surface data from high-resolution imagery remains a challenging task because of the spectral heterogeneity of complex urban land-cover types. Since the high-resolution imagery simultaneously provides plentiful spectral and spatial features, the accurate extraction of impervious surfaces depends on effective extraction and integration of spectral-spatial multifeatures. Different features have different importance for determining a certain class; traditional multifeature fusion methods that treat all features equally during classification cannot utilize the joint effect of multifeatures fully. A fusion method of distance metric learning (DML) and support vector machines is proposed to find the impervious and pervious subclasses from Chinese ZiYuan-3 (ZY-3) imagery. In the procedure of finding appropriate spectral and spatial feature combinations with DML, optimized distance metric was obtained adaptively by learning from the similarity side-information generated from labeled samples. Compared with the traditional vector stacking method that used each feature equally for multifeatures fusion, the approach achieves an overall accuracy of 91.6% (4.1% higher than the prior one) for a suburban dataset, and an accuracy of 92.7% (3.4% higher) for a downtown dataset, indicating the effectiveness of the method for accurately extracting urban impervious surface data from ZY-3 imagery.

  6. Radiometric sources for the Los Alamos National Laboratory calibration Laboratory

    SciTech Connect

    Maier, W.B. II; Holland, R.; Bender, S.; Byrd, D.; Michaud, F.D.; Moore, S.; O`Brian, T.R.

    1994-07-01

    Los Alamos is developing a laboratory that will support state of the art calibration of moderate-aperture instrumentation (< 40 cm diameter) having high spatial and thermal resolution. Highly accurate calibration in the reflected solar and thermal infrared spectral regions are required for newly developed instrumentation. Radiometric calibration of the instrumentation requires well-characterized, extensive sources of radiation from 0.45 to 12 {mu}m. For wavelengths above 2.5 {mu}m, blackbodies having temperature control and radiometric uniformity to within 100 mK are being designed and will be radiometrically characterized at the National Institute of Standards and Technology (NIST). For the spectral range 0.45--2.5 {mu}m, a ``whitebody`` integrating sphere equipped with tungsten-halogen lamps and enclosed inside a vacuum shroud will be used; this vacuum-compatible extensive standard diffuse source utilizes well-known technology and will be characterized at NIST`s existing facilities. Characterization of instrumental contrast performance for wavelengths, {lambda}, beyond 2.5 {mu}m will utilize a recently designed absolute variable-contrast IR radiometric calibrator, and preliminary data indicate that this calibrator will perform satisfactorily. Conceptual design and status of these extensive broad-band sources and of a monochromatic source to be used for spectral calibrations will be presented.

  7. Optical Imaging and Radiometric Modeling and Simulation

    NASA Technical Reports Server (NTRS)

    Ha, Kong Q.; Fitzmaurice, Michael W.; Moiser, Gary E.; Howard, Joseph M.; Le, Chi M.

    2010-01-01

    OPTOOL software is a general-purpose optical systems analysis tool that was developed to offer a solution to problems associated with computational programs written for the James Webb Space Telescope optical system. It integrates existing routines into coherent processes, and provides a structure with reusable capabilities that allow additional processes to be quickly developed and integrated. It has an extensive graphical user interface, which makes the tool more intuitive and friendly. OPTOOL is implemented using MATLAB with a Fourier optics-based approach for point spread function (PSF) calculations. It features parametric and Monte Carlo simulation capabilities, and uses a direct integration calculation to permit high spatial sampling of the PSF. Exit pupil optical path difference (OPD) maps can be generated using combinations of Zernike polynomials or shaped power spectral densities. The graphical user interface allows rapid creation of arbitrary pupil geometries, and entry of all other modeling parameters to support basic imaging and radiometric analyses. OPTOOL provides the capability to generate wavefront-error (WFE) maps for arbitrary grid sizes. These maps are 2D arrays containing digital sampled versions of functions ranging from Zernike polynomials to combination of sinusoidal wave functions in 2D, to functions generated from a spatial frequency power spectral distribution (PSD). It also can generate optical transfer functions (OTFs), which are incorporated into the PSF calculation. The user can specify radiometrics for the target and sky background, and key performance parameters for the instrument s focal plane array (FPA). This radiometric and detector model setup is fairly extensive, and includes parameters such as zodiacal background, thermal emission noise, read noise, and dark current. The setup also includes target spectral energy distribution as a function of wavelength for polychromatic sources, detector pixel size, and the FPA s charge

  8. Inverse spectral problems for differential operators on spatial networks

    NASA Astrophysics Data System (ADS)

    Yurko, V. A.

    2016-06-01

    A short survey is given of results on inverse spectral problems for ordinary differential operators on spatial networks (geometrical graphs). The focus is on the most important non-linear inverse problems of recovering coefficients of differential equations from spectral characteristics when the structure of the graph is known a priori. The first half of the survey presents results related to inverse Sturm-Liouville problems on arbitrary compact graphs. Results on inverse problems for differential operators of arbitrary order on compact graphs are then presented. In the conclusion the main results on inverse problems on non-compact graphs are given. Bibliography: 55 titles.

  9. Constrained Spectral Conditioning for spatial sound level estimation

    NASA Astrophysics Data System (ADS)

    Spalt, Taylor B.; Brooks, Thomas F.; Fuller, Christopher R.

    2016-11-01

    Microphone arrays are utilized in aeroacoustic testing to spatially map the sound emitted from an article under study. Whereas a single microphone allows only the total sound level to be estimated at the measurement location, an array permits differentiation between the contributions of distinct components. The accuracy of these spatial sound estimates produced by post-processing the array outputs is continuously being improved. One way of increasing the estimation accuracy is to filter the array outputs before they become inputs to a post-processor. This work presents a constrained method of linear filtering for microphone arrays which minimizes the total signal present on the array channels while preserving the signal from a targeted spatial location. Thus, each single-channel, filtered output for a given targeted location estimates only the signal from that location, even when multiple and/or distributed sources have been measured simultaneously. The method is based on Conditioned Spectral Analysis and modifies the Wiener-Hopf equation in a manner similar to the Generalized Sidelobe Canceller. This modified form of Conditioned Spectral Analysis is embedded within an iterative loop and termed Constrained Spectral Conditioning. Linear constraints are derived which prevent the cancellation of targeted signal due to random statistical error as well as location error in the sensor and/or source positions. The increased spatial mapping accuracy of Constrained Spectral Conditioning is shown for a simulated dataset of point sources which vary in strength. An experimental point source is used to validate the efficacy of the constraints which yield preservation of the targeted signal at the expense of reduced filtering ability. The beamforming results of a cold, supersonic jet demonstrate the qualitative and quantitative improvement obtained when using this technique to map a spatially-distributed, complex, and possibly coherent sound source.

  10. Spatially explicit spectral analysis of point clouds and geospatial data

    USGS Publications Warehouse

    Buscombe, Daniel D.

    2015-01-01

    The increasing use of spatially explicit analyses of high-resolution spatially distributed data (imagery and point clouds) for the purposes of characterising spatial heterogeneity in geophysical phenomena necessitates the development of custom analytical and computational tools. In recent years, such analyses have become the basis of, for example, automated texture characterisation and segmentation, roughness and grain size calculation, and feature detection and classification, from a variety of data types. In this work, much use has been made of statistical descriptors of localised spatial variations in amplitude variance (roughness), however the horizontal scale (wavelength) and spacing of roughness elements is rarely considered. This is despite the fact that the ratio of characteristic vertical to horizontal scales is not constant and can yield important information about physical scaling relationships. Spectral analysis is a hitherto under-utilised but powerful means to acquire statistical information about relevant amplitude and wavelength scales, simultaneously and with computational efficiency. Further, quantifying spatially distributed data in the frequency domain lends itself to the development of stochastic models for probing the underlying mechanisms which govern the spatial distribution of geological and geophysical phenomena. The software packagePySESA (Python program for Spatially Explicit Spectral Analysis) has been developed for generic analyses of spatially distributed data in both the spatial and frequency domains. Developed predominantly in Python, it accesses libraries written in Cython and C++ for efficiency. It is open source and modular, therefore readily incorporated into, and combined with, other data analysis tools and frameworks with particular utility for supporting research in the fields of geomorphology, geophysics, hydrography, photogrammetry and remote sensing. The analytical and computational structure of the toolbox is

  11. Spatially explicit spectral analysis of point clouds and geospatial data

    NASA Astrophysics Data System (ADS)

    Buscombe, Daniel

    2016-01-01

    The increasing use of spatially explicit analyses of high-resolution spatially distributed data (imagery and point clouds) for the purposes of characterising spatial heterogeneity in geophysical phenomena necessitates the development of custom analytical and computational tools. In recent years, such analyses have become the basis of, for example, automated texture characterisation and segmentation, roughness and grain size calculation, and feature detection and classification, from a variety of data types. In this work, much use has been made of statistical descriptors of localised spatial variations in amplitude variance (roughness), however the horizontal scale (wavelength) and spacing of roughness elements is rarely considered. This is despite the fact that the ratio of characteristic vertical to horizontal scales is not constant and can yield important information about physical scaling relationships. Spectral analysis is a hitherto under-utilised but powerful means to acquire statistical information about relevant amplitude and wavelength scales, simultaneously and with computational efficiency. Further, quantifying spatially distributed data in the frequency domain lends itself to the development of stochastic models for probing the underlying mechanisms which govern the spatial distribution of geological and geophysical phenomena. The software package PySESA (Python program for Spatially Explicit Spectral Analysis) has been developed for generic analyses of spatially distributed data in both the spatial and frequency domains. Developed predominantly in Python, it accesses libraries written in Cython and C++ for efficiency. It is open source and modular, therefore readily incorporated into, and combined with, other data analysis tools and frameworks with particular utility for supporting research in the fields of geomorphology, geophysics, hydrography, photogrammetry and remote sensing. The analytical and computational structure of the toolbox is described

  12. Radiometric calibration of optical microscopy and microspectroscopy apparata over a broad spectral range using a special thin-film luminescence standard

    SciTech Connect

    Valenta, J. Greben, M.

    2015-04-15

    Application capabilities of optical microscopes and microspectroscopes can be considerably enhanced by a proper calibration of their spectral sensitivity. We propose and demonstrate a method of relative and absolute calibration of a microspectroscope over an extraordinary broad spectral range covered by two (parallel) detection branches in visible and near-infrared spectral regions. The key point of the absolute calibration of a relative spectral sensitivity is application of the standard sample formed by a thin layer of Si nanocrystals with stable and efficient photoluminescence. The spectral PL quantum yield and the PL spatial distribution of the standard sample must be characterized by separate experiments. The absolutely calibrated microspectroscope enables to characterize spectral photon emittance of a studied object or even its luminescence quantum yield (QY) if additional knowledge about spatial distribution of emission and about excitance is available. Capabilities of the calibrated microspectroscope are demonstrated by measuring external QY of electroluminescence from a standard poly-Si solar-cell and of photoluminescence of Er-doped Si nanocrystals.

  13. DISENTANGLING OVERLAPPING ASTRONOMICAL SOURCES USING SPATIAL AND SPECTRAL INFORMATION

    SciTech Connect

    Jones, David E.; Kashyap, Vinay L.; Van Dyk, David A.

    2015-08-01

    We present a powerful new algorithm that combines both spatial information (event locations and the point-spread function) and spectral information (photon energies) to separate photons from overlapping sources. We use Bayesian statistical methods to simultaneously infer the number of overlapping sources, to probabilistically separate the photons among the sources, and to fit the parameters describing the individual sources. Using the Bayesian joint posterior distribution, we are able to coherently quantify the uncertainties associated with all these parameters. The advantages of combining spatial and spectral information are demonstrated through a simulation study. The utility of the approach is then illustrated by analysis of observations of FK Aqr and FL Aqr with the XMM-Newton Observatory and the central region of the Orion Nebula Cluster with the Chandra X-ray Observatory.

  14. Spectral-Spatial Hyperspectral Image Classification Based on KNN

    NASA Astrophysics Data System (ADS)

    Huang, Kunshan; Li, Shutao; Kang, Xudong; Fang, Leyuan

    2016-12-01

    Fusion of spectral and spatial information is an effective way in improving the accuracy of hyperspectral image classification. In this paper, a novel spectral-spatial hyperspectral image classification method based on K nearest neighbor (KNN) is proposed, which consists of the following steps. First, the support vector machine is adopted to obtain the initial classification probability maps which reflect the probability that each hyperspectral pixel belongs to different classes. Then, the obtained pixel-wise probability maps are refined with the proposed KNN filtering algorithm that is based on matching and averaging nonlocal neighborhoods. The proposed method does not need sophisticated segmentation and optimization strategies while still being able to make full use of the nonlocal principle of real images by using KNN, and thus, providing competitive classification with fast computation. Experiments performed on two real hyperspectral data sets show that the classification results obtained by the proposed method are comparable to several recently proposed hyperspectral image classification methods.

  15. Shaping the spatial and spectral emissivity at the diffraction limit

    SciTech Connect

    Makhsiyan, Mathilde; Bouchon, Patrick Jaeck, Julien; Pelouard, Jean-Luc; Haïdar, Riad

    2015-12-21

    Metasurfaces have attracted a growing interest for their ability to artificially tailor an electromagnetic response on various spectral ranges. In particular, thermal sources with unprecedented abilities, such as directionality or monochromaticity, have been achieved. However, these metasurfaces exhibit homogeneous optical properties whereas the spatial modulation of the emissivity up to the wavelength scale is at the crux of the design of original emitters. In this letter, we study an inhomogeneous metasurface made of a nonperiodic set of optical nano-antennas that spatially and spectrally control the emitted light up to the diffraction limit. Each antenna acts as an independent deep subwavelength emitter for given polarization and wavelength. Their juxtaposition at the subwavelength scale encodes far field multispectral and polarized images. This opens up promising breakthroughs for applications such as optical storage, anti-counterfeit devices, and multispectral emitters for biochemical sensing.

  16. A spectral method for spatial downscaling | Science Inventory ...

    EPA Pesticide Factsheets

    Complex computer models play a crucial role in air quality research. These models are used to evaluate potential regulatory impacts of emission control strategies and to estimate air quality in areas without monitoring data. For both of these purposes, it is important to calibrate model output with monitoring data to adjust for model biases and improve spatial prediction. In this paper, we propose a new spectral method to study and exploit complex relationships between model output and monitoring data. Spectral methods allow us to estimate the relationship between model output and monitoring data separately at different spatial scales, and to use model output for prediction only at the appropriate scales. The proposed method is computationally efficient and can be implemented using standard software. We apply the method to compare Community Multiscale Air Quality (CMAQ) model output with ozone measurements in the United States in July, 2005. We find that CMAQ captures large-scale spatial trends, but has low correlation with the monitoring data at small spatial scales. The National Exposure Research Laboratory′s (NERL′s)Atmospheric Modeling Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing ch

  17. GOES-R Advanced Baseline Imager: spectral response functions and radiometric biases with the NPP Visible Infrared Imaging Radiometer Suite evaluated for desert calibration sites.

    PubMed

    Pearlman, Aaron; Pogorzala, David; Cao, Changyong

    2013-11-01

    The Advanced Baseline Imager (ABI), which will be launched in late 2015 on the National Oceanic and Atmospheric Administration's Geostationary Operational Environmental Satellite R-series satellite, will be evaluated in terms of its data quality postlaunch through comparisons with other satellite sensors such as the recently launched Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the Suomi National Polar-orbiting Partnership satellite. The ABI has completed much of its prelaunch characterization and its developers have generated and released its channel spectral response functions (response versus wavelength). Using these responses and constraining a radiative transfer model with ground reflectance, aerosol, and water vapor measurements, we simulate observed top of atmosphere (TOA) reflectances for analogous visible and near infrared channels of the VIIRS and ABI sensors at the Sonoran Desert and White Sands National Monument sites and calculate the radiometric biases and their uncertainties. We also calculate sensor TOA reflectances using aircraft hyperspectral data from the Airborne Visible/Infrared Imaging Spectrometer to validate the uncertainties in several of the ABI and VIIRS channels and discuss the potential for validating the others. Once on-orbit, calibration scientists can use these biases to ensure ABI data quality and consistency to support the numerical weather prediction community and other data users. They can also use the results for ABI or VIIRS anomaly detection and resolution.

  18. Spatial-spectral characterization of focused spatially chirped broadband laser beams.

    PubMed

    Greco, Michael J; Block, Erica; Meier, Amanda K; Beaman, Alex; Cooper, Samuel; Iliev, Marin; Squier, Jeff A; Durfee, Charles G

    2015-11-20

    Proper alignment is critical to obtain the desired performance from focused spatially chirped beams, for example in simultaneous spatial and temporal focusing (SSTF). We present a simple technique for inspecting the beam paths and focusing conditions for the spectral components of a broadband beam. We spectrally resolve the light transmitted past a knife edge as it was scanned across the beam at several axial positions. The measurement yields information about spot size, M2, and the propagation paths of different frequency components. We also present calculations to illustrate the effects of defocus aberration on SSTF beams.

  19. Rapid simulation of spatial epidemics: a spectral method.

    PubMed

    Brand, Samuel P C; Tildesley, Michael J; Keeling, Matthew J

    2015-04-07

    Spatial structure and hence the spatial position of host populations plays a vital role in the spread of infection. In the majority of situations, it is only possible to predict the spatial spread of infection using simulation models, which can be computationally demanding especially for large population sizes. Here we develop an approximation method that vastly reduces this computational burden. We assume that the transmission rates between individuals or sub-populations are determined by a spatial transmission kernel. This kernel is assumed to be isotropic, such that the transmission rate is simply a function of the distance between susceptible and infectious individuals; as such this provides the ideal mechanism for modelling localised transmission in a spatial environment. We show that the spatial force of infection acting on all susceptibles can be represented as a spatial convolution between the transmission kernel and a spatially extended 'image' of the infection state. This representation allows the rapid calculation of stochastic rates of infection using fast-Fourier transform (FFT) routines, which greatly improves the computational efficiency of spatial simulations. We demonstrate the efficiency and accuracy of this fast spectral rate recalculation (FSR) method with two examples: an idealised scenario simulating an SIR-type epidemic outbreak amongst N habitats distributed across a two-dimensional plane; the spread of infection between US cattle farms, illustrating that the FSR method makes continental-scale outbreak forecasting feasible with desktop processing power. The latter model demonstrates which areas of the US are at consistently high risk for cattle-infections, although predictions of epidemic size are highly dependent on assumptions about the tail of the transmission kernel.

  20. Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on Atlas 1

    NASA Technical Reports Server (NTRS)

    Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Dougani, H.; Swift, W.

    1993-01-01

    This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory (ISO) on the ATLAS I mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v' = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of + 10%, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v' = 5 level is not observed although there is a suggestion of depletion in v' = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

  1. Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on ATLAS 1

    NASA Technical Reports Server (NTRS)

    Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Fellows, C. W.; Dougani, H.

    1993-01-01

    This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory on the ATLAS 1 mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v-prime = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of +/- 10 percent, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v-prime = 5 level is not observed although there is a suggestion of depletion in v-prime = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

  2. Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on ATLAS 1

    NASA Technical Reports Server (NTRS)

    Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Fellows, C. W.; Dougani, H.

    1993-01-01

    This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory on the ATLAS 1 mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v-prime = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of +/- 10 percent, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v-prime = 5 level is not observed although there is a suggestion of depletion in v-prime = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

  3. Mesospheric nightglow spectral survey taken by the ISO spectral spatial imager on Atlas 1

    NASA Technical Reports Server (NTRS)

    Owens, J. K.; Torr, D. G.; Torr, M. R.; Chang, T.; Fennelly, J. A.; Richards, P. G.; Morgan, M. F.; Baldridge, T. W.; Dougani, H.; Swift, W.

    1993-01-01

    This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory (ISO) on the ATLAS I mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v' = 3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of + 10%, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v' = 5 level is not observed although there is a suggestion of depletion in v' = 6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen.

  4. Spatial routing of optical beams through time-domain spatial-spectral filtering

    NASA Astrophysics Data System (ADS)

    Babbitt, W. R.; Mossberg, T. W.

    1995-04-01

    We propose a novel new method of temporal-waveform-controlled high-speed passive spatial routing of optical beams. The method provides for the redirection of optical signals contained within a single input beam into output directions that are specified entirely by temporal information encoded on the waveform of each incident signal. The routing is effected by means of deflection from spectrally structured spatial gratings that may be optically programmed into materials with or without intrinsic frequency selectivity.

  5. Spatial and spectral resolution necessary for remotely sensed vegetation studies

    NASA Technical Reports Server (NTRS)

    Rock, B. N.

    1982-01-01

    An outline is presented of the required spatial and spectral resolution needed for accurate vegetation discrimination and mapping studies as well as for determination of state of health (i.e., detection of stress symptoms) of actively growing vegetation. Good success was achieved in vegetation discrimination and mapping of a heterogeneous forest cover in the ridge and valley portion of the Appalachians using multispectral data acquired with a spatial resolution of 15 m (IFOV). A sensor system delivering 10 to 15 m spatial resolution is needed for both vegetation mapping and detection of stress symptoms. Based on the vegetation discrimination and mapping exercises conducted at the Lost River site, accurate products (vegetation maps) are produced using broad-band spectral data ranging from the .500 to 2.500 micron portion of the spectrum. In order of decreasing utility for vegetation discrimination, the four most valuable TM simulator VNIR bands are: 6 (1.55 to 1.75 microns), 3 (0.63 to 0.69 microns), 5 (1.00 to 1.30 microns) and 4 (0.76 to 0.90 microns).

  6. On the effects of spatial and spectral resolution on spatial-spectral target detection in SHARE 2012 and Bobcat 2013 hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Kaufman, Jason R.; Eismann, Michael T.; Ratliff, Bradley M.; Celenk, Mehmet

    2015-05-01

    Previous work with the Bobcat 2013 data set1 showed that spatial-spectral feature extraction on visible to near infrared (VNIR) hyperspectral imagery (HSI) led to better target detection and discrimination than spectral-only techniques; however, the aforementioned study could not consider the possible benefits of the shortwaveinfrared (SWIR) portion of the spectrum due to data limitations. In addition, the spatial resolution of the Bobcat 2013 imagery was fixed at 8cm without exploring lower spatial resolutions. In this work, we evaluate the tradeoffs in spatial and spectral resolution and spectral coverage between for a common set of targets in terms of their effects on spatial-spectral target detection performance. We show that for our spatial-spectral target detection scheme and data sets, the adaptive cosine estimator (ACE) applied to S-DAISY and pseudo Zernike moment (PZM) spatial-spectral features can distinguish between targets better than ACE applied only to the spectral imagery. In particular, S-DAISY operating on bands uniformly selected from the SWIR portion of ProSpecTIR-VS sensor imagery in conjunction with bands closely corresponding to the Airborne Real-time Cueing Hyperspectral Reconnaissance (ARCHER) sensor's VNIR bands (80 total) led to the best overall average performance in both target detection and discrimination.

  7. Novel techniques for the analysis of the TOA radiometric uncertainty

    NASA Astrophysics Data System (ADS)

    Gorroño, Javier; Banks, Andrew; Gascon, Ferran; Fox, Nigel P.; Underwood, Craig I.

    2016-10-01

    In the framework of the European Copernicus programme, the European Space Agency (ESA) has launched the Sentinel-2 (S2) Earth Observation (EO) mission which provides optical high spatial -resolution imagery over land and coastal areas. As part of this mission, a tool (named S2-RUT, from Sentinel-2 Radiometric Uncertainty Tool) estimates the radiometric uncertainties associated to each pixel using as input the top-of-atmosphere (TOA) reflectance factor images provided by ESA. The initial version of the tool has been implemented — code and user guide available1 — and integrated as part of the Sentinel Toolbox. The tool required the study of several radiometric uncertainty sources as well as the calculation and validation of the combined standard uncertainty in order to estimate the TOA reflectance factor uncertainty per pixel. Here we describe the recent research in order to accommodate novel uncertainty contributions to the TOA reflectance uncertainty estimates in future versions of the tool. The two contributions that we explore are the radiometric impact of the spectral knowledge and the uncertainty propagation of the resampling associated to the orthorectification process. The former is produced by the uncertainty associated to the spectral calibration as well as the spectral variations across the instrument focal plane and the instrument degradation. The latter results of the focal plane image propagation into the provided orthoimage. The uncertainty propagation depends on the radiance levels on the pixel neighbourhood and the pixel correlation in the temporal and spatial dimensions. Special effort has been made studying non-stable scenarios and the comparison with different interpolation methods.

  8. Spectral-Spatial Classification of Hyperspectral Images Using Hierarchical Optimization

    NASA Technical Reports Server (NTRS)

    Tarabalka, Yuliya; Tilton, James C.

    2011-01-01

    A new spectral-spatial method for hyperspectral data classification is proposed. For a given hyperspectral image, probabilistic pixelwise classification is first applied. Then, hierarchical step-wise optimization algorithm is performed, by iteratively merging neighboring regions with the smallest Dissimilarity Criterion (DC) and recomputing class labels for new regions. The DC is computed by comparing region mean vectors, class labels and a number of pixels in the two regions under consideration. The algorithm is converged when all the pixels get involved in the region merging procedure. Experimental results are presented on two remote sensing hyperspectral images acquired by the AVIRIS and ROSIS sensors. The proposed approach improves classification accuracies and provides maps with more homogeneous regions, when compared to previously proposed classification techniques.

  9. Multi-frequency scanning interferometry using variable spatial spectral filter

    NASA Astrophysics Data System (ADS)

    Choi, Samuel; Sato, Ryoko; Kato, Heiichi; Sasaki, Osami; Suzuki, Takamasa

    2014-04-01

    Recently, a variety of the optical comb-based interferometries has been developed for profilometry and tomography. However the interference amplitude and phase characteristics involving the center frequency and mode spacing of the optical comb have not been sufficiently studied. To investigate these multi-frequency interference characteristics, we proposed a broadband frequency variable quasi-comb generator utilizing 4-f optical system and a spatial spectral filter which can perform unrestricted scanning of the center frequency and mode spacing. By using a sinusoidal phase modulating interferometer with the quasi-comb generator, fundamental proof-of-principle experiments were successfully demonstrated. The interference phase fixation during the symmetrical varying of the mode spacing produced the interference amplitude peak envelope without fringes. On the other hand, it was confirmed that the interference phase was changed linearly without the amplitude change by the center frequency shift of the multi-frequency spectrum.

  10. UNDERSTANDING SPATIAL AND SPECTRAL MORPHOLOGIES OF ULTRACOMPACT H II REGIONS

    SciTech Connect

    Peters, Thomas; Banerjee, Robi; Klessen, Ralf S.; Low, Mordecai-Mark Mac; Dullemond, Cornelis P.

    2010-08-10

    The spatial morphology, spectral characteristics, and time variability of ultracompact (UC) H II regions provide strong constraints on the process of massive star formation. We have performed simulations of the gravitational collapse of rotating molecular cloud cores, including treatments of the propagation of ionizing and non-ionizing radiation. We here present synthetic radio continuum observations of H II regions from our collapse simulations, to investigate how well they agree with observation, and what we can learn about how massive star formation proceeds. We find that intermittent shielding by dense filaments in the gravitationally unstable accretion flow around the massive star leads to highly variable H II regions that do not grow monotonically, but rather flicker, growing and shrinking repeatedly. This behavior appears to be able to resolve the well-known lifetime problem. We find that multiple ionizing sources generally form, resulting in groups of UC H II regions, consistent with observations. We confirm that our model reproduces the qualitative H II region morphologies found in surveys, with generally consistent relative frequencies. We also find that simulated spectral energy distributions (SEDs) from our model are consistent with the range of observed H II region SEDs, including both regions showing a normal transition from optically thick to optically thin emission, and those with intermediate spectral slopes. In our models, anomalous slopes are solely produced by inhomogeneities in the H II region, with no contribution from dust emission at millimeter or submillimeter wavelengths. We conclude that many observed characteristics of UC H II regions appear consistent with massive star formation in fast, gravitationally unstable, accretion flows.

  11. Understanding Spatial and Spectral Morphologies of Ultracompact H II Regions

    SciTech Connect

    Peters, Thomas; Mac Low, Mordecai-Mark; Banerjee, Robi; Klessen, Ralf S.; Dullemond, Cornelis P.; /Heidelberg, Max Planck Inst. Astron.

    2010-08-25

    The spatial morphology, spectral characteristics, and time variability of ultracompact H II regions provide strong constraints on the process of massive star formation. We have performed simulations of the gravitational collapse of rotating molecular cloud cores, including treatments of the propagation of ionizing and non-ionizing radiation. We here present synthetic radio continuum observations of H II regions from our collapse simulations, to investigate how well they agree with observation, and what we can learn about how massive star formation proceeds. We find that intermittent shielding by dense filaments in the gravitationally unstable accretion flow around the massive star leads to highly variable H II regions that do not grow monotonically, but rather flicker, growing and shrinking repeatedly. This behavior appears able to resolve the well-known lifetime problem. We find that multiple ionizing sources generally form, resulting in groups of ultracompact H II regions, consistent with observations. We confirm that our model reproduces the qualitative H II region morphologies found in surveys, with generally consistent relative frequencies. We also find that simulated spectral energy distributions (SEDs) from our model are consistent with the range of observed H II region SEDs, including both regions showing a normal transition from optically thick to optically thin emission, and those with intermediate spectral slopes. In our models, anomalous slopes are solely produced by inhomogeneities in the H II region, with no contribution from dust emission at millimeter or submillimeter wavelengths. We conclude that many observed characteristics of ultracompact H II regions appear consistent with massive star formation in fast, gravitationally unstable, accretion flows.

  12. Understanding Spatial and Spectral Morphologies of Ultracompact H II Regions

    NASA Astrophysics Data System (ADS)

    Peters, Thomas; Mac Low, Mordecai-Mark; Banerjee, Robi; Klessen, Ralf S.; Dullemond, Cornelis P.

    2010-08-01

    The spatial morphology, spectral characteristics, and time variability of ultracompact (UC) H II regions provide strong constraints on the process of massive star formation. We have performed simulations of the gravitational collapse of rotating molecular cloud cores, including treatments of the propagation of ionizing and non-ionizing radiation. We here present synthetic radio continuum observations of H II regions from our collapse simulations, to investigate how well they agree with observation, and what we can learn about how massive star formation proceeds. We find that intermittent shielding by dense filaments in the gravitationally unstable accretion flow around the massive star leads to highly variable H II regions that do not grow monotonically, but rather flicker, growing and shrinking repeatedly. This behavior appears to be able to resolve the well-known lifetime problem. We find that multiple ionizing sources generally form, resulting in groups of UC H II regions, consistent with observations. We confirm that our model reproduces the qualitative H II region morphologies found in surveys, with generally consistent relative frequencies. We also find that simulated spectral energy distributions (SEDs) from our model are consistent with the range of observed H II region SEDs, including both regions showing a normal transition from optically thick to optically thin emission, and those with intermediate spectral slopes. In our models, anomalous slopes are solely produced by inhomogeneities in the H II region, with no contribution from dust emission at millimeter or submillimeter wavelengths. We conclude that many observed characteristics of UC H II regions appear consistent with massive star formation in fast, gravitationally unstable, accretion flows.

  13. Changes of spectral and radiometric properties of vegetation and soil electric properties in response to simulated surface CO2 leakage of geologically sequestered CO2

    NASA Astrophysics Data System (ADS)

    Zhou, X.; Lakkaraju, V. R.; Apple, M. E.; Dobeck, L.; Cunningham, A. B.; Spangler, L.

    2010-12-01

    During the summers (July 15 - August 12, 2009 and July 19 - August 15) CO2 release experiments to simulate CO2 leakage of geologically sequestrated CO2 at the Zero Emission Research and Technology Center (ZERT) at Bozeman, Montana, the hyperspectral reflectance and infrared radiation of vegetation canopy, soil electrical conductivity, soil moisture, soil temperature, and soil CO2 concentration were monitored. Analyses of vegetation indices derived from the spectral reflectance show that with increased soil CO2 concentration due to the surface CO2 leakage, (1) the structural independent pigment index (SIPI) increased, indicating a high carotenoid to chlorophyll ratio; (2) the chlorophyll normalized difference vegetation index (Chl NDI) decreased, suggesting a decrease in chlorophyll content with time; (3) pigment specific simple ratios (both PSSRa and PSSRb) were reduced for stressed vegetation station compared to that at the control site, indicating a reduction in both chlorophyll a and chlorophyll b; and (4) Normalized-difference first derivative index (NFDI) decreased for the CO2 stressed vegetation while it is almost constant at the control site. All four indices were found to be sensitive to stress in vegetation induced by high soil CO2 concentration. Inversion of biophysical parameters from radiative transfer modeling shows that the chlorophyll content and structural parameter decrease with increasing accumulated CO2 leakage. Temporal variation of the vegetation brightness temperature as measured by two infrared radiometers shows different patterns for the vegetation at the CO2 leaking hotspot and control site, indicating the stress among vegetation caused by the CO2 leakage changed the radiometric properties of vegetation. Multivariate analyses of the observed time series of the soil data show that (1) the slope of the linear relationship between the bulk soil EC and soil moisture increases (from 2.067 to 4.982) with increase in the soil CO2 concentration due

  14. Lansat MSS, Radiometric Processing Improvement

    NASA Astrophysics Data System (ADS)

    Saunier, Sebastien; Salgues, Germain; Gascon, Ferran; Biaasutti, Roberto

    2016-08-01

    The reprocessing campaigns of Landsat European Space Agency (ESA) data archive have been initiated since 3 years [1]. As part of this project, the processing algorithms have been upgraded. This article focuses on the radiometric processing of historical data observed with the Multi Spectral Scanner (MSS) instruments on board Landsat 1, 2, 3, 4 and 5.The Landsat MSS data have been recorded data from 1972 up to 1990. The MSS instruments have been designed with four visible bands covering the near / infrared regions of the electromagnetic spectrum, allowing the spatial sampling of our Earth surface at 60 meter.The current calibration method has shown some limitations in case of data observed out of mid latitude areas, where the Earth surface is bright because of desert or snow. The resulting image data suffers from saturations and is not fit for the potential application purposes.Although, when saturation exist, further investigations have shown that the radiometry of the raw data involved in the production of the Level 1 images is generally correct. As consequences, experiments have been undertaken to adapt the current processing in order to produce image data saturation free products.

  15. Spectral and spatial selectivity of luminance vision in reef fish

    PubMed Central

    Siebeck, Ulrike E.; Wallis, Guy Michael; Litherland, Lenore; Ganeshina, Olga; Vorobyev, Misha

    2014-01-01

    Luminance vision has high spatial resolution and is used for form vision and texture discrimination. In humans, birds and bees luminance channel is spectrally selective—it depends on the signals of the long-wavelength sensitive photoreceptors (bees) or on the sum of long- and middle-wavelength sensitive cones (humans), but not on the signal of the short-wavelength sensitive (blue) photoreceptors. The reasons of such selectivity are not fully understood. The aim of this study is to reveal the inputs of cone signals to high resolution luminance vision in reef fish. Sixteen freshly caught damselfish, Pomacentrus amboinensis, were trained to discriminate stimuli differing either in their color or in their fine patterns (stripes vs. cheques). Three colors (“bright green”, “dark green” and “blue”) were used to create two sets of color and two sets of pattern stimuli. The “bright green” and “dark green” were similar in their chromatic properties for fish, but differed in their lightness; the “dark green” differed from “blue” in the signal for the blue cone, but yielded similar signals in the long-wavelength and middle-wavelength cones. Fish easily learned to discriminate “bright green” from “dark green” and “dark green” from “blue” stimuli. Fish also could discriminate the fine patterns created from “dark green” and “bright green”. However, fish failed to discriminate fine patterns created from “blue” and “dark green” colors, i.e., the colors that provided contrast for the blue-sensitive photoreceptor, but not for the long-wavelength sensitive one. High resolution luminance vision in damselfish, Pomacentrus amboinensis, does not have input from the blue-sensitive cone, which may indicate that the spectral selectivity of luminance channel is a general feature of visual processing in both aquatic and terrestrial animals. PMID:25324727

  16. Spectral and spatial selectivity of luminance vision in reef fish.

    PubMed

    Siebeck, Ulrike E; Wallis, Guy Michael; Litherland, Lenore; Ganeshina, Olga; Vorobyev, Misha

    2014-01-01

    Luminance vision has high spatial resolution and is used for form vision and texture discrimination. In humans, birds and bees luminance channel is spectrally selective-it depends on the signals of the long-wavelength sensitive photoreceptors (bees) or on the sum of long- and middle-wavelength sensitive cones (humans), but not on the signal of the short-wavelength sensitive (blue) photoreceptors. The reasons of such selectivity are not fully understood. The aim of this study is to reveal the inputs of cone signals to high resolution luminance vision in reef fish. Sixteen freshly caught damselfish, Pomacentrus amboinensis, were trained to discriminate stimuli differing either in their color or in their fine patterns (stripes vs. cheques). Three colors ("bright green", "dark green" and "blue") were used to create two sets of color and two sets of pattern stimuli. The "bright green" and "dark green" were similar in their chromatic properties for fish, but differed in their lightness; the "dark green" differed from "blue" in the signal for the blue cone, but yielded similar signals in the long-wavelength and middle-wavelength cones. Fish easily learned to discriminate "bright green" from "dark green" and "dark green" from "blue" stimuli. Fish also could discriminate the fine patterns created from "dark green" and "bright green". However, fish failed to discriminate fine patterns created from "blue" and "dark green" colors, i.e., the colors that provided contrast for the blue-sensitive photoreceptor, but not for the long-wavelength sensitive one. High resolution luminance vision in damselfish, Pomacentrus amboinensis, does not have input from the blue-sensitive cone, which may indicate that the spectral selectivity of luminance channel is a general feature of visual processing in both aquatic and terrestrial animals.

  17. Breast density estimation from high spectral and spatial resolution MRI.

    PubMed

    Li, Hui; Weiss, William A; Medved, Milica; Abe, Hiroyuki; Newstead, Gillian M; Karczmar, Gregory S; Giger, Maryellen L

    2016-10-01

    A three-dimensional breast density estimation method is presented for high spectral and spatial resolution (HiSS) MR imaging. Twenty-two patients were recruited (under an Institutional Review Board--approved Health Insurance Portability and Accountability Act-compliant protocol) for high-risk breast cancer screening. Each patient received standard-of-care clinical digital x-ray mammograms and MR scans, as well as HiSS scans. The algorithm for breast density estimation includes breast mask generating, breast skin removal, and breast percentage density calculation. The inter- and intra-user variabilities of the HiSS-based density estimation were determined using correlation analysis and limits of agreement. Correlation analysis was also performed between the HiSS-based density estimation and radiologists' breast imaging-reporting and data system (BI-RADS) density ratings. A correlation coefficient of 0.91 ([Formula: see text]) was obtained between left and right breast density estimations. An interclass correlation coefficient of 0.99 ([Formula: see text]) indicated high reliability for the inter-user variability of the HiSS-based breast density estimations. A moderate correlation coefficient of 0.55 ([Formula: see text]) was observed between HiSS-based breast density estimations and radiologists' BI-RADS. In summary, an objective density estimation method using HiSS spectral data from breast MRI was developed. The high reproducibility with low inter- and low intra-user variabilities shown in this preliminary study suggest that such a HiSS-based density metric may be potentially beneficial in programs requiring breast density such as in breast cancer risk assessment and monitoring effects of therapy.

  18. Calibrated infrared ground/air radiometric spectrometer

    NASA Astrophysics Data System (ADS)

    Silk, J. K.; Schildkraut, Elliot Robert; Bauldree, Russell S.; Goodrich, Shawn M.

    1996-06-01

    The calibrated infrared ground/air radiometric spectrometer (CIGARS) is a new high performance, multi-purpose, multi- platform Fourier transform spectrometer (FPS) sensor. It covers the waveband from 0.2 to 12 micrometer, has spectral resolution as fine as 0.3 cm-1, and records over 100 spectra per second. Two CIGARS units are being used for observations of target signatures in the air or on the ground from fixed or moving platforms, including high performance jet aircraft. In this paper we describe the characteristics and capabilities of the CIGARS sensor, which uses four interchangeable detector modules (Si, InGaAs, InSb, and HgCdTe) and two optics modules, with internal calibration. The data recording electronics support observations of transient events, even without precise information on the timing of the event. We present test and calibration data on the sensitivity, spectral resolution, stability, and spectral rate of CIGARS, and examples of in- flight observations of real targets. We also discuss plans for adapting CIGARS for imaging spectroscopy observations, with simultaneous spectral and spatial data, by replacing the existing detectors with a focal plane array (FPA).

  19. A spectral-spatial kernel-based method for hyperspectral imagery classification

    NASA Astrophysics Data System (ADS)

    Li, Li; Ge, Hongwei; Gao, Jianqiang

    2017-02-01

    Spectral-based classification methods have gained increasing attention in hyperspectral imagery classification. Nevertheless, the spectral cannot fully represent the inherent spatial distribution of the imagery. In this paper, a spectral-spatial kernel-based method for hyperspectral imagery classification is proposed. Firstly, the spatial feature was extracted by using area median filtering (AMF). Secondly, the result of the AMF was used to construct spatial feature patch according to different window sizes. Finally, using the kernel technique, the spectral feature and the spatial feature were jointly used for the classification through a support vector machine (SVM) formulation. Therefore, for hyperspectral imagery classification, the proposed method was called spectral-spatial kernel-based support vector machine (SSF-SVM). To evaluate the proposed method, experiments are performed on three hyperspectral images. The experimental results show that an improvement is possible with the proposed technique in most of the real world classification problems.

  20. Cloud Filtering Using a Bi-Spectral Spatial Coherence Approach

    NASA Technical Reports Server (NTRS)

    Guillory, Anthony R.; Lecue, Juan M.; Jedlovec, Gary J.; Whitworth, Brandon N.

    1998-01-01

    The research in this paper focuses on describing a technique developed for cloud filtering using a bi-spectral approach on GOES-8/9 Imager data. The application was developed for use with infrared retrievals of geophysical parameters in mind, where cloud cover contaminates the derived product. However, numerous potential applications of the technique exist. The technique will be described and a preliminary validation of the algorithm will be presented. Although initially based on the spatial coherence approach from Coakley and Brethereton (1982), it has evolved to utilize a difference image of the I I and 3.9 micrometer channels on the GOES-8/9 Imager. This image is very similar to that produced by Nelson and Ellrod (1996). During the daytime the technique makes use of the varying solar reflectance in the 3.9 micrometer channel by clouds and land to identify cloudy pixels. While at night, the technique makes use of the varying emissivity of the clouds in the scene to discriminate between clear and cloudy pixels. The technique applies three basic threshold tests to produce the final cloud filtered image: 1) a standard deviation threshold to detect the spatial variance in the scene, 2) a difference threshold between adjacent pixels, and 3) a simple infrared temperature threshold. The first test is applied to the entire image at once, then in a second pass the next two tests are applied. The final infrared temperature threshold is only meant to identify the coldest clouds that might pass the previous tests. The technique performs well during the daytime, while nighttime performance is degraded but is promising. The technique has proven to be robust and shows great promise of meeting its original goal of cloud filtering for use in an infrared retrieval algorithm for use in climate studies.

  1. Cloud Filtering Using a Bi-Spectral Spatial Coherence Approach

    NASA Technical Reports Server (NTRS)

    Guillory, Anthony R.; Lecue, Juan M.; Jedlovec, Gary J.; Whitworth, Brandon N.

    1998-01-01

    The research in this paper focuses on describing a technique developed for cloud filtering using a bi-spectral approach on GOES-8/9 Imager data. The application was developed for use with infrared retrievals of geophysical parameters in mind, where cloud cover contaminates the derived product. However, numerous potential applications of the technique exist. The technique will be described and a preliminary validation of the algorithm will be presented. Although initially based on the spatial coherence approach from Coakley and Brethereton (1982), it has evolved to utilize a difference image of the 11 and 3.9 micrometer channels on the GOES-8/9 Imager. This image is very similar to that produced by Nelson and Ellrod (1996). During the daytime the technique makes use of the varying solar reflectance in the 3.9 micrometer channel by clouds and land to identify cloudy pixels. While at night, the technique makes use of the varying emissivity of the clouds in the scene to discriminate between clear and cloudy pixels. The technique applies three basic threshold tests to produce the final cloud filtered image: 1) a standard deviation threshold to detect the spatial variance in the scene, 2) a difference threshold between adjacent pixels, and 3) a simple infrared temperature threshold. The first test is applied to the entire image at once, then in a second pass the next two tests are applied. The final infrared temperature threshold is only meant to identify the coldest clouds that might pass the previous tests. The technique performs well during the daytime, while nighttime performance is degraded but is promising. The technique has proven to be robust and shows great promise of meeting its original goal of cloud filtering for use in an infrared retrieval algorithm for use in climate studies.

  2. Pansharpening remotely sensed data by using nonnegative matrix factorization and spectral-spatial degradation models

    NASA Astrophysics Data System (ADS)

    Farhi, Nezha; Karoui, Moussa Sofiane; Djerriri, Khelifa; Boukerch, Issam

    2016-10-01

    In this paper, a new pansharpening method, which uses nonnegative matrix factorization, is proposed to enhance the spatial resolution of remote sensing multispectral images. This method, based on the linear spectral unmixing concept and called joint spatial-spectral variables nonnegative matrix factorization, optimizes, by new iterative and multiplicative update rules, a joint-variables criterion that exploits spatial and spectral degradation models between the considered images. This criterion considers only two unknown high spatial-spectral resolutions variables. The proposed method is tested on synthetic and real datasets and its effectiveness, in spatial and spectral domains, is evaluated with established performance criteria. Results show the good performances of the proposed approach in comparison with other standard literature ones.

  3. Spatial and Spectral Brightness Enhancement of High Power Semiconductor Lasers

    NASA Astrophysics Data System (ADS)

    Leidner, Jordan Palmer

    The performance of high-power broad-area diode lasers is inhibited by beam filamentation induced by free-carrier-based self-focusing. The resulting beam degradation limits their usage in high-brightness, high-power applications such as pumping fiber lasers, and laser cutting, welding, or marking. Finite-difference propagation method simulations via RSoft's BeamPROP commercial simulation suite and a custom-built MATLAB code were used for the study and design of laser cavities that suppress or avoid filamentation. BeamPROP was used to design a tapered, passive, multi-mode interference cavity for the creation of a self-phase-locking laser array, which is comprised of many single-mode gain elements coupled to a wide output coupler to avoid damage from local high optical intensities. MATLAB simulations were used to study the effects of longitudinal and lateral cavity confinement on lateral beam quality in conventional broad-area lasers. This simulation was expanded to design a laser with lateral gain and index prescription that is predicted to operate at or above state-of-the-art powers while being efficiently coupled to conventional telecom single-mode optical fibers. Experimentally, a commercial broad-area laser was coupled in the far-field to a single-mode fiber Bragg grating to provide grating-stabilized single-mode laser feedback resulting in measured spectral narrowing for efficient pump absorption. Additionally a 19 GHz-span, spatially resolved, self-heterodyne measurement was made of a broad-area laser to study the evolution/devolution of the mode content of the emitted laser beam with increasing power levels.

  4. Change Detection Method with Spatial and Spectral Information from Deep Learning

    NASA Astrophysics Data System (ADS)

    Lyu, Haobo; Lu, Hui

    2017-04-01

    Change detection is a key application of remote sensing technology. For multi-spectral images, the available spatial information and useful spectral information is both helpful for data analysis, especially change detection tasks. However, it is difficult that how to learn the changed features from spatial and spectral information meantime in one model. In this paper, we proposed a new method which combines 2-dimensional Convolutional Neural Network and 1-dimensional Recurrent Neural Network for learn changed feature. Compared with only using spectral information, the spatial information will be helpful to overcome temporal spectral variance issues. Our method extracts the spatial difference and spectral difference meantime, and these change information will be balanced in final memory cell of our model, and the leaned change information will be exploited to character change features for change detection. Finally, experiments are performed on two multi-temporal datasets, and the results show superior performance on detecting changes with spatial information and spectral information. Index Terms— Change detection, multi-temporal images, recurrent neural network, convolutional neural network , deep learning, spatial information, spectral information

  5. Data Field Modeling and Spectral-Spatial Feature Fusion for Hyperspectral Data Classification.

    PubMed

    Liu, Da; Li, Jianxun

    2016-12-16

    Classification is a significant subject in hyperspectral remote sensing image processing. This study proposes a spectral-spatial feature fusion algorithm for the classification of hyperspectral images (HSI). Unlike existing spectral-spatial classification methods, the influences and interactions of the surroundings on each measured pixel were taken into consideration in this paper. Data field theory was employed as the mathematical realization of the field theory concept in physics, and both the spectral and spatial domains of HSI were considered as data fields. Therefore, the inherent dependency of interacting pixels was modeled. Using data field modeling, spatial and spectral features were transformed into a unified radiation form and further fused into a new feature by using a linear model. In contrast to the current spectral-spatial classification methods, which usually simply stack spectral and spatial features together, the proposed method builds the inner connection between the spectral and spatial features, and explores the hidden information that contributed to classification. Therefore, new information is included for classification. The final classification result was obtained using a random forest (RF) classifier. The proposed method was tested with the University of Pavia and Indian Pines, two well-known standard hyperspectral datasets. The experimental results demonstrate that the proposed method has higher classification accuracies than those obtained by the traditional approaches.

  6. Data Field Modeling and Spectral-Spatial Feature Fusion for Hyperspectral Data Classification

    PubMed Central

    Liu, Da; Li, Jianxun

    2016-01-01

    Classification is a significant subject in hyperspectral remote sensing image processing. This study proposes a spectral-spatial feature fusion algorithm for the classification of hyperspectral images (HSI). Unlike existing spectral-spatial classification methods, the influences and interactions of the surroundings on each measured pixel were taken into consideration in this paper. Data field theory was employed as the mathematical realization of the field theory concept in physics, and both the spectral and spatial domains of HSI were considered as data fields. Therefore, the inherent dependency of interacting pixels was modeled. Using data field modeling, spatial and spectral features were transformed into a unified radiation form and further fused into a new feature by using a linear model. In contrast to the current spectral-spatial classification methods, which usually simply stack spectral and spatial features together, the proposed method builds the inner connection between the spectral and spatial features, and explores the hidden information that contributed to classification. Therefore, new information is included for classification. The final classification result was obtained using a random forest (RF) classifier. The proposed method was tested with the University of Pavia and Indian Pines, two well-known standard hyperspectral datasets. The experimental results demonstrate that the proposed method has higher classification accuracies than those obtained by the traditional approaches. PMID:27999259

  7. NASA Radiometric Characterization

    NASA Technical Reports Server (NTRS)

    Holekamp, Kara

    2006-01-01

    This viewgraph presentation reviews the characterization of radiometric data by NASA. The objective was to perform radiometric vicarious calibrations of imagery and compare with vendor-provided calibration coefficients. The approach was to use multiple, well-characterized sites. These sites are widely used by the NASA science community for radiometric characterization of airborne and space borne sensors. Using the data from these sites, the investigators performed independent characterizations with independent teams. Each team has slightly different measurement techniques and data processing methods.

  8. Spectral-spatial classification combined with diffusion theory based inverse modeling of hyperspectral images

    NASA Astrophysics Data System (ADS)

    Paluchowski, Lukasz A.; Bjorgan, Asgeir; Nordgaard, Hâvard B.; Randeberg, Lise L.

    2016-02-01

    Hyperspectral imagery opens a new perspective for biomedical diagnostics and tissue characterization. High spectral resolution can give insight into optical properties of the skin tissue. However, at the same time the amount of collected data represents a challenge when it comes to decomposition into clusters and extraction of useful diagnostic information. In this study spectral-spatial classification and inverse diffusion modeling were employed to hyperspectral images obtained from a porcine burn model using a hyperspectral push-broom camera. The implemented method takes advantage of spatial and spectral information simultaneously, and provides information about the average optical properties within each cluster. The implemented algorithm allows mapping spectral and spatial heterogeneity of the burn injury as well as dynamic changes of spectral properties within the burn area. The combination of statistical and physics informed tools allowed for initial separation of different burn wounds and further detailed characterization of the injuries in short post-injury time.

  9. Characterizing Intra-Die Spatial Correlation Using Spectral Density Fitting Method

    NASA Astrophysics Data System (ADS)

    Fu, Qiang; Luk, Wai-Shing; Tao, Jun; Yan, Changhao; Zeng, Xuan

    In this paper, a spectral domain method named the SDF (Spectral Density Fitting) method for intra-die spatial correlation function extraction is presented. Based on theoretical analysis of random field, the spectral density, as the spectral domain counterpart of correlation function, is employed to estimate the parameters of the correlation function effectively in the spectral domain. Compared with the existing extraction algorithm in the original spatial domain, the SDF method can obtain the same quality of results in the spectral domain. In actual measurement process, the unavoidable measurement error with arbitrary frequency components would greatly confound the extraction results. A filtering technique is further developed to diminish the high frequency components of the measurement error and recover the data from noise contamination for parameter estimation. Experimental results have shown that the SDF method is practical and stable.

  10. Double Fourier spatio-spectral interferometry - Combining high spectral and high spatial resolution in the near infrared

    NASA Astrophysics Data System (ADS)

    Mariotti, J.-M.; Ridgway, S. T.

    1988-04-01

    The authors present a new method to combine high angular with high spectral resolution interferometry. The fundamental characteristic of this method is that it is sequential in spatial frequency space and multiplexed in spectrum space. Hence, it combines the multiplex advantage of the Fourier Transform Spectrometry (when detector noise is dominant) with the non-redundancy advantage of pupil plane interferometry, that is, independence of the spatial transfer function from the seeing. The principle can be applied to single pupil interferometry, especially if coupled with detector mosaics, and to arrays of two or more telescopes. In this context, the natural preservation of the spectral phase gradient is very interesting. As for differential speckle interferometry, it should provide super-resolution in the spatial domain, and a possibility of estimating the object phase, leading to diffraction limited imaging.

  11. Small satellite radiometric measurement system

    SciTech Connect

    Weber, P.G.

    1992-01-01

    A critical need for the US Global Change Research Program is to provide continuous, well-calibrated radiometric data for the earth's radiation budget. This paper describes a new, compact, relatively light-weight, adaptable radiometer which will provide both spectrally integrated measurements and data in selected spectral bands. The radiometer design is suitable for use on small satellites, aircraft, or remotely piloted aircraft (RPAs). An example of the implementation of this radiometer on a small satellite is given. Significant benefits derive from simultaneous measurements of specific narrow (in wavelength) spectral features; such data may be obtained by combining LARI with a compact spectrometer on the same platform. Well-chosen satellite orbits allow one to use data from other satellites (e.g. DMSP) to enhance the data product, or to provide superior coverage of specific locations. 23 refs.

  12. Small satellite radiometric measurement system

    SciTech Connect

    Weber, P.G.

    1992-01-01

    A critical need for the US Global Change Research Program is to provide continuous, well-calibrated radiometric data for the earth`s radiation budget. This paper describes a new, compact, relatively light-weight, adaptable radiometer which will provide both spectrally integrated measurements and data in selected spectral bands. The radiometer design is suitable for use on small satellites, aircraft, or remotely piloted aircraft (RPAs). An example of the implementation of this radiometer on a small satellite is given. Significant benefits derive from simultaneous measurements of specific narrow (in wavelength) spectral features; such data may be obtained by combining LARI with a compact spectrometer on the same platform. Well-chosen satellite orbits allow one to use data from other satellites (e.g. DMSP) to enhance the data product, or to provide superior coverage of specific locations. 23 refs.

  13. MODIS On-orbit Radiometric Calibration Algorithms

    NASA Astrophysics Data System (ADS)

    Xiong, X.; Chiang, K.; Adimi, F.; Sun, J.; Esposito, J.; Barnes, W. L.

    2002-05-01

    The MODerate Resolution Imaging Spectroradiometer (MODIS), a key instrument for NASA's Earth Observing System (EOS), consists of 36 spectral bands with wavelengths ranging form 0.41 micron to 14.4 microns and spatial resolutions of 0.25km (2 bands), 0.5km (5 bands), and 1.0km at nadir. The 36 spectral bands are distributed on four Focal Plane Assemblies (FPA): visible (VIS), near-infrared (NIR), short- and mid-wave infrared (SMIR), and long-wave infrared (LWIR). A Spectral Radiometric Calibration Assembly (SRCA), built into the MODIS instrument, is used to characterize the relative band to band registration and VIS and NIR bands' spectral stability. The MODIS 2-sided paddle wheel scan mirror provides a -55 degree to +55 degree scan of the Earth covering a 10km (at nadir) along track by 2330km along scan swath. The MODIS ProtoFlight Model (PFM) was launched on-board the EOS Terra spacecraft on December 18, 1999 (Sun-synchronous near polar orbit, 10:30 am equator crossing time, descending node). MODIS has been providing the science community global coverage of the land, oceans, and atmosphere. A second instrument, the Flight Model 1 (FM1), will be launched on the EOS Aqua spacecraft in April 2002 (Sun-synchronous near polar orbit, 1:30 pm equator crossing time, ascending node). The MODIS Characterization Support Team (MCST), funded by the MODIS Science Team, is responsible for the instrument pre-launch and on-orbit calibration and characterization and for developing, maintaining, and improving the Level 1B algorithm that converts the instrument digital counts to radiometrically calibrated top of the atmosphere (TOA) radiance and reflectance products. The Level1B data, along with other science products (oceans, land, and atmosphere), are freely available to the public through NASA Goddard Earth Science (GES) Distributed Active Archive Center (DAAC). The MODIS 20 reflective solar bands (RSB) from 0.41 to 2.1 microns are calibrated on-orbit by a solar diffuser (SD) and

  14. NASA IKONOS Radiometric Characterization

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Frisbee, Troy; Zanoni, Vicki; Blonski, Slawek; Daehler, Erik; Grant, Brennan; Holekamp, Kara; Ryan, Robert; Sellers, Richard; Smith, Charles

    2002-01-01

    The objective of this program: Perform radiometric vicarious calibrations of IKQNOS imagery and compare with Space Imaging calibration coefficients The approach taken: utilize multiple well-characterized sites which are widely used by the NASA science community for radiometric characterization of airborne and spaceborne sensors; and to Perform independent characterizations with independent teams. Each team has slightly different measurement techniques and data processing methods.

  15. Zoom lens design for a novel imaging spectrometer that controls spatial and spectral resolution individually.

    PubMed

    Choi, Jin; Kim, T H; Kong, H J; Lee, Jong Ung

    2006-05-20

    A novel imaging spectrometer can individually control spatial and spectral resolution by using zoom lenses as the foreoptics of the system and a focusing lens. By varying the focal length we can use the focusing lens to change the spatial and spectral dimensions; with the foreoptics, however, we can change only the spatial dimension. Therefore the spectral resolution and the spectral range are affected by the zoom ratio of the focusing lens, whereas the spatial resolution and the field of view are affected by the multiplication of the zoom ratios of the foreoptics and the focusing lens. By properly combining two zoom ratios, we can control the spectral resolution with a fixed spatial resolution or the spatial resolution with a fixed spectral resolution. For an imaging spectrometer with this novel zooming function, we used the lens module method and third-order aberration theory to design an initial four-group zoom system with an external entrance pupil for the focusing lens. Furthermore, using the optical design software CODE V, we obtained an optimized zoom lens with a focal-length range of 50 to 150 mm. Finally, the zoom system with its transmission grating in the Littrow configuration performs satisfactorily as the focusing lens of an imaging spectrometer in the wavelength range 450-900 nm.

  16. Spatial-spectral signature modeling for solid targets in hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Kaufman, Jason R.; Meola, Joseph

    2017-05-01

    Spatial-spectral feature extraction algorithms - such as those based on spatial descriptors applied to selected spectral bands within a hyperspectral image - can provide additional discrimination capability beyond traditional spectral-only approaches. However, when attempting to detect a target with such algorithms, an exemplar target signature is often manually derived from the hyperspectral images representation in the spatial-spectral feature space. This requires a reference image in which the targets location is known. Additionally, the scenebased signature captures only the representation of the target under certain collection conditions from a specific sensor, namely, illumination level and atmospheric composition, look angle, and target pose against a specific background. A detection algorithm utilizing this spatial-spectral signature (or the spatial descriptor itself) that is sensitive to changes in these collection conditions could suffer a loss in performance should the new conditions significantly deviate from the exemplars case. To begin to overcome these limitations, we formulate and evaluate the effectiveness of a modeling technique for synthesizing exemplar spatial-spectral signatures for solid targets, particularly when the spatial structure of the target of interest varies due to pose or obscuration by the background, and when applicable, the target temperature varies. We assess the impact of these changes on a group of spatial descriptors responses to guide the modeling process for a set of two-dimensional targets specifically designed for this study. The sources of variability that most affect each descriptor are captured in target subspaces, which then form the basis of new spatial-spectral target detection algorithms.

  17. Evaluation on Radiometric Capability of Chinese Optical Satellite Sensors

    PubMed Central

    Yang, Aixia; Zhong, Bo; Wu, Shanlong; Liu, Qinhuo

    2017-01-01

    The radiometric capability of on-orbit sensors should be updated on time due to changes induced by space environmental factors and instrument aging. Some sensors, such as Moderate Resolution Imaging Spectroradiometer (MODIS), have onboard calibrators, which enable real-time calibration. However, most Chinese remote sensing satellite sensors lack onboard calibrators. Their radiometric calibrations have been updated once a year based on a vicarious calibration procedure, which has affected the applications of the data. Therefore, a full evaluation of the sensors’ radiometric capabilities is essential before quantitative applications can be made. In this study, a comprehensive procedure for evaluating the radiometric capability of several Chinese optical satellite sensors is proposed. In this procedure, long-term radiometric stability and radiometric accuracy are the two major indicators for radiometric evaluation. The radiometric temporal stability is analyzed by the tendency of long-term top-of-atmosphere (TOA) reflectance variation; the radiometric accuracy is determined by comparison with the TOA reflectance from MODIS after spectrally matching. Three Chinese sensors including the Charge-Coupled Device (CCD) camera onboard Huan Jing 1 satellite (HJ-1), as well as the Visible and Infrared Radiometer (VIRR) and Medium-Resolution Spectral Imager (MERSI) onboard the Feng Yun 3 satellite (FY-3) are evaluated in reflective bands based on this procedure. The results are reasonable, and thus can provide reliable reference for the sensors’ application, and as such will promote the development of Chinese satellite data. PMID:28117745

  18. Evaluation on Radiometric Capability of Chinese Optical Satellite Sensors.

    PubMed

    Yang, Aixia; Zhong, Bo; Wu, Shanlong; Liu, Qinhuo

    2017-01-22

    The radiometric capability of on-orbit sensors should be updated on time due to changes induced by space environmental factors and instrument aging. Some sensors, such as Moderate Resolution Imaging Spectroradiometer (MODIS), have onboard calibrators, which enable real-time calibration. However, most Chinese remote sensing satellite sensors lack onboard calibrators. Their radiometric calibrations have been updated once a year based on a vicarious calibration procedure, which has affected the applications of the data. Therefore, a full evaluation of the sensors' radiometric capabilities is essential before quantitative applications can be made. In this study, a comprehensive procedure for evaluating the radiometric capability of several Chinese optical satellite sensors is proposed. In this procedure, long-term radiometric stability and radiometric accuracy are the two major indicators for radiometric evaluation. The radiometric temporal stability is analyzed by the tendency of long-term top-of-atmosphere (TOA) reflectance variation; the radiometric accuracy is determined by comparison with the TOA reflectance from MODIS after spectrally matching. Three Chinese sensors including the Charge-Coupled Device (CCD) camera onboard Huan Jing 1 satellite (HJ-1), as well as the Visible and Infrared Radiometer (VIRR) and Medium-Resolution Spectral Imager (MERSI) onboard the Feng Yun 3 satellite (FY-3) are evaluated in reflective bands based on this procedure. The results are reasonable, and thus can provide reliable reference for the sensors' application, and as such will promote the development of Chinese satellite data.

  19. Spatial-Spectral Classification Based on the Unsupervised Convolutional Sparse Auto-Encoder for Hyperspectral Remote Sensing Imagery

    NASA Astrophysics Data System (ADS)

    Han, Xiaobing; Zhong, Yanfei; Zhang, Liangpei

    2016-06-01

    Current hyperspectral remote sensing imagery spatial-spectral classification methods mainly consider concatenating the spectral information vectors and spatial information vectors together. However, the combined spatial-spectral information vectors may cause information loss and concatenation deficiency for the classification task. To efficiently represent the spatial-spectral feature information around the central pixel within a neighbourhood window, the unsupervised convolutional sparse auto-encoder (UCSAE) with window-in-window selection strategy is proposed in this paper. Window-in-window selection strategy selects the sub-window spatial-spectral information for the spatial-spectral feature learning and extraction with the sparse auto-encoder (SAE). Convolution mechanism is applied after the SAE feature extraction stage with the SAE features upon the larger outer window. The UCSAE algorithm was validated by two common hyperspectral imagery (HSI) datasets - Pavia University dataset and the Kennedy Space Centre (KSC) dataset, which shows an improvement over the traditional hyperspectral spatial-spectral classification methods.

  20. Spectral and Spatial Pattern Recognition in Digital Imagery

    DTIC Science & Technology

    1992-12-01

    soil axis used in the PVI equations is based on 16 data points in Texas, from four dates in 1975. "It is unlikely that such a small and geographically ...This process requires that multiple images of a specific geographic region be taken in several spectral bands and that the images be in good...used to image the geographic region. For ease of explanation and understanding, only two imaging bands will be used in the discussion on supervised

  1. Simultaneous Spectral-Spatial Feature Selection and Extraction for Hyperspectral Images.

    PubMed

    Zhang, Lefei; Zhang, Qian; Du, Bo; Huang, Xin; Tang, Yuan Yan; Tao, Dacheng

    2016-09-12

    In hyperspectral remote sensing data mining, it is important to take into account of both spectral and spatial information, such as the spectral signature, texture feature, and morphological property, to improve the performances, e.g., the image classification accuracy. In a feature representation point of view, a nature approach to handle this situation is to concatenate the spectral and spatial features into a single but high dimensional vector and then apply a certain dimension reduction technique directly on that concatenated vector before feed it into the subsequent classifier. However, multiple features from various domains definitely have different physical meanings and statistical properties, and thus such concatenation has not efficiently explore the complementary properties among different features, which should benefit for boost the feature discriminability. Furthermore, it is also difficult to interpret the transformed results of the concatenated vector. Consequently, finding a physically meaningful consensus low dimensional feature representation of original multiple features is still a challenging task. In order to address these issues, we propose a novel feature learning framework, i.e., the simultaneous spectral-spatial feature selection and extraction algorithm, for hyperspectral images spectral-spatial feature representation and classification. Specifically, the proposed method learns a latent low dimensional subspace by projecting the spectral-spatial feature into a common feature space, where the complementary information has been effectively exploited, and simultaneously, only the most significant original features have been transformed. Encouraging experimental results on three public available hyperspectral remote sensing datasets confirm that our proposed method is effective and efficient.

  2. Spatial and spectral superconvergence of discontinuous Galerkin method for hyperbolic problems

    NASA Astrophysics Data System (ADS)

    Marchandise, Emilie; Chevaugeon, Nicolas; Remacle, Jean-Francois

    2008-06-01

    In this paper, we analyze the spatial and spectral superconvergence properties of one-dimensional hyperbolic conservation law by a discontinuous Galerkin (DG) method. The analyses combine classical mathematical arguments with MATLAB experiments. Some properties of the DG schemes are discovered using discrete Fourier analyses: superconvergence of the numerical wave numbers, Radau structure of the X spatial error.

  3. Unsupervised Spectral-Spatial Feature Selection-Based Camouflaged Object Detection Using VNIR Hyperspectral Camera

    PubMed Central

    2015-01-01

    The detection of camouflaged objects is important for industrial inspection, medical diagnoses, and military applications. Conventional supervised learning methods for hyperspectral images can be a feasible solution. Such approaches, however, require a priori information of a camouflaged object and background. This letter proposes a fully autonomous feature selection and camouflaged object detection method based on the online analysis of spectral and spatial features. The statistical distance metric can generate candidate feature bands and further analysis of the entropy-based spatial grouping property can trim the useless feature bands. Camouflaged objects can be detected better with less computational complexity by optical spectral-spatial feature analysis. PMID:25879073

  4. A Comparison of Spatial and Spectral Image Resolution for Mapping Invasive Plants in Coastal California

    NASA Astrophysics Data System (ADS)

    Underwood, Emma C.; Ustin, Susan L.; Ramirez, Carlos M.

    2007-01-01

    We explored the potential of detecting three target invasive species: iceplant ( Carpobrotus edulis), jubata grass ( Cortaderia jubata), and blue gum ( Eucalyptus globulus) at Vandenberg Air Force Base, California. We compared the accuracy of mapping six communities (intact coastal scrub, iceplant invaded coastal scrub, iceplant invaded chaparral, jubata grass invaded chaparral, blue gum invaded chaparral, and intact chaparral) using four images with different combinations of spatial and spectral resolution: hyperspectral AVIRIS imagery (174 wavebands, 4 m spatial resolution), spatially degraded AVIRIS (174 bands, 30 m), spectrally degraded AVIRIS (6 bands, 4 m), and both spatially and spectrally degraded AVIRIS (6 bands, 30 m, i.e., simulated Landsat ETM data). Overall success rates for classifying the six classes was 75% (kappa 0.7) using full resolution AVIRIS, 58% (kappa 0.5) for the spatially degraded AVIRIS, 42% (kappa 0.3) for the spectrally degraded AVIRIS, and 37% (kappa 0.3) for the spatially and spectrally degraded AVIRIS. A true Landsat ETM image was also classified to illustrate that the results from the simulated ETM data were representative, which provided an accuracy of 50% (kappa 0.4). Mapping accuracies using different resolution images are evaluated in the context of community heterogeneity (species richness, diversity, and percent species cover). Findings illustrate that higher mapping accuracies are achieved with images possessing high spectral resolution, thus capturing information across the visible and reflected infrared solar spectrum. Understanding the tradeoffs in spectral and spatial resolution can assist land managers in deciding the most appropriate imagery with respect to target invasives and community characteristics.

  5. A comparison of spatial and spectral image resolution for mapping invasive plants in coastal california.

    PubMed

    Underwood, Emma C; Ustin, Susan L; Ramirez, Carlos M

    2007-01-01

    We explored the potential of detecting three target invasive species: iceplant (Carpobrotus edulis), jubata grass (Cortaderia jubata), and blue gum (Eucalyptus globulus) at Vandenberg Air Force Base, California. We compared the accuracy of mapping six communities (intact coastal scrub, iceplant invaded coastal scrub, iceplant invaded chaparral, jubata grass invaded chaparral, blue gum invaded chaparral, and intact chaparral) using four images with different combinations of spatial and spectral resolution: hyperspectral AVIRIS imagery (174 wavebands, 4 m spatial resolution), spatially degraded AVIRIS (174 bands, 30 m), spectrally degraded AVIRIS (6 bands, 4 m), and both spatially and spectrally degraded AVIRIS (6 bands, 30 m, i.e., simulated Landsat ETM data). Overall success rates for classifying the six classes was 75% (kappa 0.7) using full resolution AVIRIS, 58% (kappa 0.5) for the spatially degraded AVIRIS, 42% (kappa 0.3) for the spectrally degraded AVIRIS, and 37% (kappa 0.3) for the spatially and spectrally degraded AVIRIS. A true Landsat ETM image was also classified to illustrate that the results from the simulated ETM data were representative, which provided an accuracy of 50% (kappa 0.4). Mapping accuracies using different resolution images are evaluated in the context of community heterogeneity (species richness, diversity, and percent species cover). Findings illustrate that higher mapping accuracies are achieved with images possessing high spectral resolution, thus capturing information across the visible and reflected infrared solar spectrum. Understanding the tradeoffs in spectral and spatial resolution can assist land managers in deciding the most appropriate imagery with respect to target invasives and community characteristics.

  6. Visible/infrared radiometric calibration station

    SciTech Connect

    Byrd, D.A.; Maier, W.B. II; Bender, S.C.; Holland, R.F.; Michaud, F.D.; Luettgen, A.L.; Christensen, R.W.; O`Brian, T.R.

    1994-07-01

    We have begun construction of a visible/infrared radiometric calibration station that will allow for absolute calibration of optical and IR remote sensing instruments with clear apertures less than 16 inches in diameter in a vacuum environment. The calibration station broadband sources will be calibrated at the National Institute of Standards and Technology (NIST) and allow for traceable absolute radiometric calibration to within {plus_minus}3% in the visible and near IR (0.4--2.5 {mu}m), and less than {plus_minus}1% in the infrared, up to 12 {mu}m. Capabilities for placing diffraction limited images or for sensor full-field flooding will exist. The facility will also include the calibration of polarization and spectral effects, spatial resolution, field of view performance, and wavefront characterization. The configuration of the vacuum calibration station consists of an off-axis 21 inch, f/3.2, parabolic collimator with a scanning fold flat in collimated space. The sources are placed, via mechanisms to be described, at the focal plane of the off-axis parabola. Vacuum system pressure will be in the 10{sup {minus}6} Torr range. The broadband white-light source is a custom design by LANL with guidance from Labsphere Inc. The continuous operating radiance of the integrating sphere will be from 0.0--0.006 W/cm{sup 2}/Sr/{mu}m (upper level quoted for {approximately}500 nm wavelength). The blackbody source is also custom designed at LANL with guidance from NIST. The blackbody temperature will be controllable between 250--350{degrees}K. Both of the above sources have 4.1 inch apertures with estimated radiometric instability at less than 1%. The designs of each of these units will be described. The monochromator and interferometer light sources are outside the vacuum, but all optical relay and beam shaping optics are enclosed within the vacuum calibration station. These sources are described, as well as the methodology for alignment and characterization.

  7. Radiometric correction procedure study

    NASA Technical Reports Server (NTRS)

    Colby, C.; Sands, R.; Murphrey, S.

    1978-01-01

    A comparison of MSS radiometric processing techniques identified as a preferred radiometric processing technique a procedure which equalizes the mean and standard deviation of detector-specific histograms of uncalibrated scene data. Evaluation of MSS calibration data demonstrated that the relationship between detector responses is essentially linear over the range of intensities typically observed in MSS data, and that the calibration wedge data possess a high degree of temporal stability. An analysis of the preferred radiometric processing technique showed that it could be incorporated into the MDP-MSS system without a major redesign of the system, and with minimal impact on system throughput.

  8. Combined spectral and spatial processing of ERTS imagery data

    NASA Technical Reports Server (NTRS)

    Haralick, R. M.; Shanmugam, K. S.

    1973-01-01

    A procedure for extracting a set of textural features for ERTS-1 MSS data is presented. The textural features were combined with a set of spectral features and were used to develop a classification algorithm for identifying the land use categories of blocks of digital MSS data. The classification algorithm was derived from a training set of 314 blocks and tested on a set of 310 blocks. The overall accuracy of the classifier was found to be 83.5% on seven land use categories.

  9. Hyperspectral Imagery Super-Resolution by Compressive Sensing Inspired Dictionary Learning and Spatial-Spectral Regularization

    PubMed Central

    Huang, Wei; Xiao, Liang; Liu, Hongyi; Wei, Zhihui

    2015-01-01

    Due to the instrumental and imaging optics limitations, it is difficult to acquire high spatial resolution hyperspectral imagery (HSI). Super-resolution (SR) imagery aims at inferring high quality images of a given scene from degraded versions of the same scene. This paper proposes a novel hyperspectral imagery super-resolution (HSI-SR) method via dictionary learning and spatial-spectral regularization. The main contributions of this paper are twofold. First, inspired by the compressive sensing (CS) framework, for learning the high resolution dictionary, we encourage stronger sparsity on image patches and promote smaller coherence between the learned dictionary and sensing matrix. Thus, a sparsity and incoherence restricted dictionary learning method is proposed to achieve higher efficiency sparse representation. Second, a variational regularization model combing a spatial sparsity regularization term and a new local spectral similarity preserving term is proposed to integrate the spectral and spatial-contextual information of the HSI. Experimental results show that the proposed method can effectively recover spatial information and better preserve spectral information. The high spatial resolution HSI reconstructed by the proposed method outperforms reconstructed results by other well-known methods in terms of both objective measurements and visual evaluation. PMID:25608212

  10. Spatial-spectral data redundancy requirement for Fourier ptychographic microscopy

    NASA Astrophysics Data System (ADS)

    Sun, Jiasong; Zhang, Yuzhen; Chen, Qian; Zuo, Chao

    2016-10-01

    Fourier ptychographic microscopy (FPM) is a new computational super-resolution approach, which can obtain not only the correct object function, but also the pupil aberration, the LED misalignment, and beyond. Although many state-mixed FPM techniques have been proposed to achieve higher data acquisition efficiency and recovery accuracy in the past few years, little is known that their reconstruction performance highly depends on the data redundancy in both object and frequency domains. In this paper, we explore the spatial and spectrum data redundancy requirements for the FPM recovery process to introduce sampling criteria for the conventional and state-mixed FPM techniques in both object and frequency space.

  11. Radiometric instrumentation and measurements guide for photovoltaic performance testing

    SciTech Connect

    Myers, D.

    1997-04-01

    The Photovoltaic Module and Systems Performance and Engineering Project at the National Renewable Energy Laboratory performs indoor and outdoor standardization, testing, and monitoring of the performance of a wide range of photovoltaic (PV) energy conversion devices and systems. The PV Radiometric Measurements and Evaluation Team (PVSRME) within that project is responsible for measurement and characterization of natural and artificial optical radiation which stimulates the PV effect. The PV manufacturing and research and development community often approaches project members for technical information and guidance. A great area of interest is radiometric instrumentation, measurement techniques, and data analysis applied to understanding and improving PV cell, module, and system performance. At the Photovoltaic Radiometric Measurements Workshop conducted by the PVSRME team in July 1995, the need to communicate knowledge of solar and optical radiometric measurements and instrumentation, gained as a result of NREL`s long-term experiences, was identified as an activity that would promote improved measurement processes and measurement quality in the PV research and manufacturing community. The purpose of this document is to address the practical and engineering need to understand optical and solar radiometric instrument performance, selection, calibration, installation, and maintenance applicable to indoor and outdoor radiometric measurements for PV calibration, performance, and testing applications. An introductory section addresses radiometric concepts and definitions. Next, concepts essential to spectral radiometric measurements are discussed. Broadband radiometric instrumentation and measurement concepts are then discussed. Each type of measurement serves as an important component of the PV cell, module, and system performance measurement and characterization process.

  12. Evaluating the Usability of Spatially-Interpolated Endmembers for Spectral Mixture Analysis with Imaging Spectroscopy

    NASA Astrophysics Data System (ADS)

    Shi, C.; Wang, L.

    2016-12-01

    A number of upcoming spaceborne imaging spectrometer missions such as the Environmental Mapping and Analysis Program (EnMAP) and the Hyperspectral Infrared Imager (HyspIRI) will provide the unprecedented opportunities for global land cover mapping with hyperspectral data. However, due to the moderate spatial resolution of those satellite sensors, a mixture of disparate materials is inevitably contained in a pixel. Although spectral mixture analysis is capable of analyzing land cover composition at the subpixel level, most studies use invariant, image-wide endmember spectra for the estimation of fractional abundances. It is widely acknowledged that due to spatial and temporal variations in environmental, atmospheric, and physical conditions as well as variable illumination conditions, the measured spectral signature of an endmember may vary across a remotely sensed image. Since spectral signatures of an endmember present in nearby pixels tend to be similar with one another, this property of spatial autocorrelation may provide a solution to the endmember variability problem. In this study, the usability of spatially-interpolated endmembers for spectral mixture analysis is thoroughly evaluated. Three major steps are involved: (1) the extraction of image endmembers using a supervised classification method; (2) spatial interpolation of endmember spectra for each mixed pixel via the synthesis of image endmember pixels present in its spatial neighborhood; (3) the estimation of fractional abundances using spatially-interpolated endmember spectra. Two well-known spatial interpolators, namely, Inverse Distance Weighting and Ordinary Kriging, are employed to synthesize endmember spectra on a per-pixel basis. A 1 m resolution image acquired by the Airborne Imaging Spectroradiometer for Applications (AISA) sensor was adopted, and spatially aggregated to 30 m resolution for abundance estimation. The results showed that more accurate abundance maps could be produced by the use of

  13. Schroedinger Eigenmaps with nondiagonal potentials for spatial-spectral clustering of hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Cahill, Nathan D.; Czaja, Wojciech; Messinger, David W.

    2014-06-01

    Schroedinger Eigenmaps (SE) has recently emerged as a powerful graph-based technique for semi-supervised manifold learning and recovery. By extending the Laplacian of a graph constructed from hyperspectral imagery to incorporate barrier or cluster potentials, SE enables machine learning techniques that employ expert/labeled information provided at a subset of pixels. In this paper, we show how different types of nondiagonal potentials can be used within the SE framework in a way that allows for the integration of spatial and spectral information in unsupervised manifold learning and recovery. The nondiagonal potentials encode spatial proximity, which when combined with the spectral proximity information in the original graph, yields a framework that is competitive with state-of-the-art spectral/spatial fusion approaches for clustering and subsequent classification of hyperspectral image data.

  14. Spectral and Spatial Characterization of Protein Loaded PLGA Nanoparticles

    PubMed Central

    Zidan, Ahmed S.; Rahman, Ziyaur; Habib, Muhammad J.; Khan, Mansoor A.

    2011-01-01

    The objective of this study was to evaluate near infrared (NIR) spectroscopy and imaging as approaches to assess drug contents in poly(dl-lactide-co-glycolide) (PLGA) based nanoparticles of a model protein, cyclosporine A (CyA). A 6-factors 12-runs designed set of experiments with Plackett–Burman (PB) screening was applied in order to examine the effects of drug loading (X1), polymer loading (X2), emulsifier concentration (X3), stirring rate (X4), type of organic solvent (X5), and ratio of organic to aqueous phases' volumes (X6), on drug entrapment efficiency (EFF). After omitting the factors with nonsignificant influences on EFF, a reduced mathematical relationship, EFF = 48.34 + 7.3X1 − 29.95X3, was obtained to explain the effect of the significant factors on EFF. Using two different sets for calibration and validation, the developed NIR calibration model was able to assess CyA contents within the 12 PB formulations. NIR spectral imaging was capable of clearly distinguishing the 12 formulations, both qualitatively and quantitatively. A good correlation with a coefficient of 0.9727 was obtained for constructing a quantile-quantile plot for the actual drug loading percentage and the % standard deviation obtained for the drug loading prediction using the hyperspectral images. PMID:19774658

  15. Spatial correlation properties and the spectral intensity distributions of focused Gaussian Schell-model array beams

    NASA Astrophysics Data System (ADS)

    Ji, Xiaoling; Pu, Zhengcai; Jia, Xinhong

    2009-07-01

    The spatial correlation properties and the spectral intensity distributions of focused Gaussian Schell-model (GSM) array beams are studied in detail. The closed-form expressions for the spectral degree of coherence and the spectral intensity of focused GSM array beams are derived. It is shown that the spectral degree of coherence of focused GSM array beams is the same as that of focused GSM beams in the focal plane. On the other hand, it is found that, in the focal plane the spectral intensity distribution of focused GSM array beams is the fringe pattern when the value of the coherence length is small. However, it becomes one peak located at the center as the value of the coherence length is large enough. In the focal plane, the spectral intensity maximum increases and the width of the normalized spectral intensity distribution decreases as the beam number increases. In general, for GSM array beams, the width of the modulus of the spectral degree of coherence in the focal plane always exceeds that of the normalized spectral intensity distribution, which is different from the behavior of focused GSM beams. In addition, the power in the bucket (PIB) and the beam propagation factor ( M2 factor) are also discussed. The main results are explained physically.

  16. Spectral analysis and filtering techniques in digital spatial data processing

    USGS Publications Warehouse

    Pan, Jeng-Jong

    1989-01-01

    A filter toolbox has been developed at the EROS Data Center, US Geological Survey, for retrieving or removing specified frequency information from two-dimensional digital spatial data. This filter toolbox provides capabilities to compute the power spectrum of a given data and to design various filters in the frequency domain. Three types of filters are available in the toolbox: point filter, line filter, and area filter. Both the point and line filters employ Gaussian-type notch filters, and the area filter includes the capabilities to perform high-pass, band-pass, low-pass, and wedge filtering techniques. These filters are applied for analyzing satellite multispectral scanner data, airborne visible and infrared imaging spectrometer (AVIRIS) data, gravity data, and the digital elevation models (DEM) data. -from Author

  17. Adjusting Spectral Indices for Spectral Response Function Differences of Very High Spatial Resolution Sensors Simulated from Field Spectra

    PubMed Central

    Cundill, Sharon L.; van der Werff, Harald M. A.; van der Meijde, Mark

    2015-01-01

    The use of data from multiple sensors is often required to ensure data coverage and continuity, but differences in the spectral characteristics of sensors result in spectral index values being different. This study investigates spectral response function effects on 48 spectral indices for cultivated grasslands using simulated data of 10 very high spatial resolution sensors, convolved from field reflectance spectra of a grass covered dike (with varying vegetation condition). Index values for 48 indices were calculated for original narrow-band spectra and convolved data sets, and then compared. The indices Difference Vegetation Index (DVI), Global Environmental Monitoring Index (GEMI), Enhanced Vegetation Index (EVI), Modified Soil-Adjusted Vegetation Index (MSAVI2) and Soil-Adjusted Vegetation Index (SAVI), which include the difference between the near-infrared and red bands, have values most similar to those of the original spectra across all 10 sensors (1:1 line mean 1:1R2 > 0.960 and linear trend mean ccR2 > 0.997). Additionally, relationships between the indices’ values and two quality indicators for grass covered dikes were compared to those of the original spectra. For the soil moisture indicator, indices that ratio bands performed better across sensors than those that difference bands, while for the dike cover quality indicator, both the choice of bands and their formulation are important. PMID:25781511

  18. Characterizing the temporal and spatial variability of longwave infrared spectral images of targets and backgrounds

    NASA Astrophysics Data System (ADS)

    Jeganathan, Nirmalan; Kerekes, John; Rosario, Dalton

    2017-05-01

    Following the public release of the Spectral and Polarimetric Imagery Collection Experiment (SPICE) dataset, a persistent imaging experiment dataset collected by the Army Research Laboratory (ARL), the data were analyzed and materials in the scene characterized temporally and spatially using radiance data. The noise equivalent spectral radiance provided by the sensor manufacturer was compared with instrument noise calculated from in-scene information, and found to be comparable given differences in laboratory setting and real-life conditions. The processed dataset have regular "inconsistent cubes," specifically for data collected immediately after blackbody measurements, which were automatically executed approximately at each hour mark. Omitting these erroneous data, three target detection algorithms (adaptive coherent/cosine estimator, spectral angle mapper, and spectral matched filter) were tested on the temporal data using two target spectra (noon and midnight). The spectral matched filter produced the best detection rate for both noon and midnight target spectra for a 24-hrs period.

  19. Spectral Analysis of Spatial Series Data of Pathologic Tissue: A Study on Small Intestine in ICR Mouse

    NASA Astrophysics Data System (ADS)

    Mise, Keiji; Sumi, Ayako; Kobayashi, Nobumichi; Torigoe, Toshihiko; Ohtomo, Norio

    2009-01-01

    We examined the usefulness of spectral analysis for investigating quantitatively the spatial pattern of pathologic tissue. To interpret the results obtained from real tissue, we constructed a two-dimensional spatial model of the tissue. Spectral analysis was applied to the spatial series data, which were obtained from the real tissue and model. From the results of spectral analysis, spatial patterns of the tissue and model were characterized quantitatively in reference to the frequencies and powers of the spectral peaks in power spectral densities (PSDs). The results for the model were essentially consistent with those for the tissue. It was concluded that the model was capable of adequately explaining the spatial pattern of the tissue. It is anticipated that spectral analysis will become a useful tool for characterizing the spatial pattern of the tissue quantitatively, resulting in an automated first screening of pathological specimens.

  20. Comparison of local and global angular interpolation applied to spectral-spatial EPR image reconstruction.

    PubMed

    Ahn, Kang-Hyun; Halpern, Howard J

    2007-03-01

    Spectral-spatial images reconstructed from a small number of projections suffer from streak artifacts that are seen as noise, particularly in the spectral dimension. Interpolation in projection space can reduce artifacts in the reconstructed images. The reduction of background artifacts improves lineshape fitting. In this work, we compared the performances of angular interpolation implemented using linear, cubic B-spline, and sinc methods. Line width maps were extracted from 4-D EPR images of phantoms using spectral fitting to evaluate each interpolation method and its robustness to noise. Results from experiment and simulation showed that the cubic B-spline, angular interpolation was preferable to either sinc or linear interpolation methods.

  1. Spectral Preferences and the Role of Spatial Coherence in Simultaneous Integration in Gray Treefrogs (Hyla chrysoscelis)

    PubMed Central

    Bee, Mark A.

    2010-01-01

    The perceptual analysis of acoustic scenes may often require the integration of simultaneous sounds arising from a single source. Few studies have investigated the cues that promote simultaneous integration in the context of acoustic communication in nonhuman animals. This study of Cope’s gray treefrog (Hyla chrysoscelis) examined female preferences based on spectral features of conspecific male advertisement calls to test the hypothesis that cues related to common spatial origin promote the perceptual integration of simultaneous signal elements (harmonics). The typical advertisement call comprises two harmonically related spectral peaks near 1.1 kHz and 2.2 kHz. Subjects generally exhibited preferences for calls with two spatially coherent harmonics over alternatives with just one harmonic. When given a choice between a spatially coherent call (both harmonics originating from the same speaker) and a spatially incoherent call (each harmonic from different spatially separated speakers), subjects preferentially chose the former in the same relative proportions in which it was chosen over single-harmonic alternatives. Preferences for spatially coherent calls over spatially incoherent alternatives did not appear to result from greater difficulty localizing the spatially incoherent sources. These results are consistent with the hypothesis that spatial coherence promotes perceptual integration of simultaneous signal elements in frogs. PMID:20853948

  2. The Importance of High Spatial and Appropriate Spectral Resolution Spectroscopy

    NASA Technical Reports Server (NTRS)

    Gull, Theodore

    2007-01-01

    Many diverse astronomical sources are resolved with diffraction-limited large telescopes. Application of appropriate dispersion spectroscopy unveils much information on the physics of these objects ranging from gamma ray bursters in host galaxies, star-formation regions and central engines in nearby galaxies, structures in galactic nebulae, resolved binaries with mass exchange, extended winds of massive stars, protoplanetary systems, and comets, asteroids and planets within our own solar system. Active optics and interferometers coupled with spectrographs can provide near-diffraction-limited spectroscopy from the ground but only longward of one micron. Below one micron, and certainly below 6000A, we must turn to space-based large telescopes equipped with spectrographs capable of providing spatially diffraction-limited spectroscopy of astronomical sources. Examples will be presented from the HST/STIS, ground-based and other instruments on science that has been accomplished. Suggestions will be made of what might be possible, and limitations thereof, with future large monolithic, multiple mirror or interferometric telescopes equipped with spectrographs that would be matched to the diffraction limit of the telescope.

  3. S4: A spatial-spectral model for speckle suppression

    SciTech Connect

    Fergus, Rob; Hogg, David W.; Oppenheimer, Rebecca; Brenner, Douglas; Pueyo, Laurent

    2014-10-20

    High dynamic range imagers aim to block or eliminate light from a very bright primary star in order to make it possible to detect and measure far fainter companions; in real systems, a small fraction of the primary light is scattered, diffracted, and unocculted. We introduce S4, a flexible data-driven model for the unocculted (and highly speckled) light in the P1640 spectroscopic coronagraph. The model uses principal components analysis (PCA) to capture the spatial structure and wavelength dependence of the speckles, but not the signal produced by any companion. Consequently, the residual typically includes the companion signal. The companion can thus be found by filtering this error signal with a fixed companion model. The approach is sensitive to companions that are of the order of a percent of the brightness of the speckles, or up to 10{sup –7} times the brightness of the primary star. This outperforms existing methods by a factor of two to three and is close to the shot-noise physical limit.

  4. Assessment of spectral, misregistration, and spatial uncertainties inherent in the cross-calibration study

    USGS Publications Warehouse

    Chander, G.; Helder, D.L.; Aaron, D.; Mishra, N.; Shrestha, A.K.

    2013-01-01

    Cross-calibration of satellite sensors permits the quantitative comparison of measurements obtained from different Earth Observing (EO) systems. Cross-calibration studies usually use simultaneous or near-simultaneous observations from several spaceborne sensors to develop band-by-band relationships through regression analysis. The investigation described in this paper focuses on evaluation of the uncertainties inherent in the cross-calibration process, including contributions due to different spectral responses, spectral resolution, spectral filter shift, geometric misregistrations, and spatial resolutions. The hyperspectral data from the Environmental Satellite SCanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY and the EO-1 Hyperion, along with the relative spectral responses (RSRs) from the Landsat 7 Enhanced Thematic Mapper (TM) Plus and the Terra Moderate Resolution Imaging Spectroradiometer sensors, were used for the spectral uncertainty study. The data from Landsat 5 TM over five representative land cover types (desert, rangeland, grassland, deciduous forest, and coniferous forest) were used for the geometric misregistrations and spatial-resolution study. The spectral resolution uncertainty was found to be within 0.25%, spectral filter shift within 2.5%, geometric misregistrations within 0.35%, and spatial-resolution effects within 0.1% for the Libya 4 site. The one-sigma uncertainties presented in this paper are uncorrelated, and therefore, the uncertainties can be summed orthogonally. Furthermore, an overall total uncertainty was developed. In general, the results suggested that the spectral uncertainty is more dominant compared to other uncertainties presented in this paper. Therefore, the effect of the sensor RSR differences needs to be quantified and compensated to avoid large uncertainties in cross-calibration results.

  5. Simultaneous spectral/spatial detection of edges for hyperspectral imagery: the HySPADE algorithm revisited

    NASA Astrophysics Data System (ADS)

    Resmini, Ronald G.

    2012-06-01

    The hyperspectral/spatial detection of edges (HySPADE) algorithm, originally published in 2004 [1], has been modified and applied to a wider diversity of hyperspectral imagery (HSI) data. As originally described in [1], HySPADE operates by converting the naturally two-dimensional edge detection process based on traditional image analysis methods into a series of one-dimensional edge detections based on spectral angle. The HySPADE algorithm: i) utilizes spectral signature information to identify edges; ii) requires only the spectral information of the HSI scene data and does not require a spectral library nor spectral matching against a library; iii) facilitates simultaneous use of all spectral information; iv) does not require endmember or training data selection; v) generates multiple, independent data points for statistical analysis of detected edges; vi) is robust in the presence of noise; and vii) may be applied to radiance, reflectance, and emissivity data--though it is applied to radiance and reflectance spectra (and their principal components transformation) in this report. HySPADE has recently been modified to use Euclidean distance values as an alternative to spectral angle. It has also been modified to use an N x N-pixel sliding window in contrast to the 2004 version which operated only on spatial subset image chips. HySPADE results are compared to those obtained using traditional (Roberts and Sobel) edge-detection methods. Spectral angle and Euclidean distance HySPADE results are superior to those obtained using the traditional edge detection methods; the best results are obtained by applying HySPADE to the first few, information-containing bands of principal components transformed data (both radiance and reflectance). However, in practice, both the Euclidean distance and spectral angle versions of HySPADE should be applied and their results compared. HySPADE results are shown; extensions of the HySPADE concept are discussed as are applications for Hy

  6. Compact hybrid real-time hyperspectral imaging system with high effective spatial, spectral, and temporal resolution

    NASA Astrophysics Data System (ADS)

    Roth, Filip; Abbadi, Ahmad; Herman, Ondrej; Pavelek, Martin; Prenosil, Vaclav

    2016-10-01

    Medical endoscopes for image-guided surgery commonly use standard color image sensors, discarding any more detailed spectral information. Medical spectroscopy devices with various spectral working ranges are specialized to specific medical procedures and in general are not usable for image-guided surgery due to limitations in spatial or temporal resolution. In this paper, we present an initial demonstrator of hyperspectral endoscope, composed of two image sensors with complementing parameters. Using this hybrid approach, combining sensors with different spatial and spectral resolutions and spectral ranges, we obtain improved coverage of all the respective parameters. After digitally processing and merging the video streams, while maintaining the better features of both, we obtain an imaging system providing high effective spatial, spectral, and temporal resolution. The system is based on field programmable gate arrays. It provides real-time video output (60 Hz), which is usable for navigation during image-guided surgery. The flexible system architecture allows for an easy extension of the processing algorithms and enables minimal video signal latency. Physical dimensions and portability of the system are comparable to standard off-the-shelf medical endoscope cameras. The device can output both processed video and standard visible light video signals on one or more video outputs of the system. The resulting processed video signal obtained from the combined image sensor data greatly increases the amount of useful information available to the end user.

  7. High spatial resolution three-dimensional mapping of vegetation spectral dynamics using computer vision

    Treesearch

    Jonathan P. Dandois; Erle C. Ellis

    2013-01-01

    High spatial resolution three-dimensional (3D) measurements of vegetation by remote sensing are advancing ecological research and environmental management. However, substantial economic and logistical costs limit this application, especially for observing phenological dynamics in ecosystem structure and spectral traits. Here we demonstrate a new aerial remote sensing...

  8. Advanced Remote-sensing Imaging Emission Spectrometer (ARIES): AIRS Spectral Resolution with MODIS Spatial Resolution

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Chahine, Moustafa T.; Aumann, Hartmut H.; OCallaghan, Fred G.; Broberg, Steve E.

    2006-01-01

    This paper describes a space based instrument concept that will provide scientists with data needed to support key ongoing and future Earth System Science investigations. The measurement approach builds on the observations made by AIRS and MODIS and exceeds their capability with improved spatial and spectral resolution. This paper describes the expected products and the instrument concept that can meet those requirements.

  9. Hyperspectral image spectral-spatial classification using local tensor discriminant feature extraction

    NASA Astrophysics Data System (ADS)

    Wu, Di; Zhang, Ye; Zhong, Sheng Wei; Zhou, Guang Jiao

    2016-10-01

    Classification of real-world remote sensing images is a challenging task because of complex spectral-spatial information with high-dimensional feature vectors. Most of the traditional classification approaches directly treat data as vectors, which usually results in a small sample size problem and abundant redundant information; thus, they inevitably degrade the performance of the classifier. To overcome the drawbacks, we take advantage of the benefits of local scatters and tensor representation and propose a framework for hyperspectral image (HSI) classification through combining local tensor discriminant analysis (LTDA) with spectral-spatial feature extraction. First, we use a well-known spectral-spatial feature extraction approach to extract abundant spectral-spatial features as feature tensors. Then, based on class label information, LTDA is used to eliminate redundant information and to extract discriminant feature tensors for the subsequent classification. Two real HSIs are used as experimental datasets. The obtained results indicate that the proposed method exhibits good performance, while using a small number of training samples.

  10. Spectral-spatial classification of hyperspectral images with semi-supervised graph learning

    NASA Astrophysics Data System (ADS)

    Luo, Renbo; Liao, Wenzhi; Zhang, Hongyan; Pi, Youguo; Philips, Wilfried

    2016-10-01

    In this paper, we propose a novel semi-supervised graph leaning method to fuse spectral (of original hyperspectral (HS) image) and spatial (from morphological features) information for classification of HS image. In our proposed semi-supervised graph, samples are connected according to either label information (labeled samples) or their k-nearest spectral and spatial neighbors (unlabeled samples). Furthermore, we link the unlabeled sample with all labeled samples in one class which is the closest to this unlabeled sample in both spectral and spatial feature spaces. Thus, the connected samples have similar characteristics on both spectral and spatial domains, and have high possibilities to belong to the same class. By exploiting the fused semi-supervised graph, we then get transformation matrices to project high-dimensional HS image and morphological features to their lower dimensional subspaces. The final classification map is obtained by concentrating the lower-dimensional features together as an input of SVM classifier. Experimental results on a real hyperspectral data demonstrate the efficiency of our proposed semi-supervised fusion method. Compared to the methods using unsupervised fusion or supervised fusion, the proposed semi-supervised fusion method enables improved performances on classification. Moreover, the classification performances keep stable even when a small number of labeled training samples is available.

  11. Spectral absorbance and spatial distribution of macular pigment using heterochromatic flicker photometry.

    PubMed

    Wooten, Billy R; Hammond, Billy R

    2005-05-01

    The validity of the heterochromatic flicker photometric (HFP) technique for measuring macular pigment (MP) was assessed by evaluating the spatial density and spectral absorption curves of normal subjects. Standard Maxwellian view optics were used to measure MP spatial density and spectral absorption curves. Four subjects with normal color vision and one protanope were tested. All of the subjects were experienced psychophysical observers. Spatial density profiles for all subjects were nearly symmetric. The width of the spatial distribution, at half maximal density, averaged 0.70 degrees (standard deviation = 0.15). A first-order exponential decay with eccentricity described the distribution profile well (average r = 0.95). The shape of the spectral absorption curves matched an ex vivo template closely at wavelengths greater than approximately 430 nm. Stimulus size did not influence the derived spectral curves. Based on data from this study and others, the HFP method appears to be a valid method for measuring MP density in subjects without retinal disease.

  12. Can spectral-spatial image segmentation be used to discriminate experimental burn wounds?

    NASA Astrophysics Data System (ADS)

    Paluchowski, Lukasz A.; Nordgaard, Håvard B.; Bjorgan, Asgeir; Hov, Håkon; Berget, Sissel M.; Randeberg, Lise L.

    2016-10-01

    Hyperspectral imaging (HSI) is a noncontact and noninvasive optical modality emerging the field of medical research. The goal of this study was to determine the ability of HSI and image segmentation to discriminate burn wounds in a preclinical porcine model. A heated brass rod was used to introduce burn wounds of graded severity in a pig model and a sequence of hyperspectral data was recorded up to 8-h postinjury. The hyperspectral images were processed by an unsupervised spectral-spatial segmentation algorithm. Segmentation was validated using results from histology. The proposed algorithm was compared to K-means segmentation and was found superior. The obtained segmentation maps revealed separated zones within the burn sites, indicating a variation in burn severity. The suggested image-processing scheme allowed mapping dynamic changes of spectral properties within the burn wounds over time. The results of this study indicate that unsupervised spectral-spatial segmentation applied on hyperspectral images can discriminate burn injuries of varying severity.

  13. Spatial-Spectral EOF analysis of AIRS data: an exploratory study

    NASA Astrophysics Data System (ADS)

    Huang, X.; Yung, Y. L.; Lambrigtsen, B. H.

    2003-12-01

    We apply spatial-spectral EOF analysis to 14 days of AIRS (Atmospheric Infrared Sounder) calibrated radiance data collected over the tropics and subtropics (32S to 32N) from July 1 to July 14, 2003. We limit our analysis to the nadir-view (scan angle less than 5o) spectra only. After the quality control procedure, we have an average of 1400 spectra over this period for each 4o by 5o grid box. We obtain a 14-day averaged spectrum for each grid box and apply EOF analysis to these averaged spectra to obtain principal components in spectrally resolved radiance and associated spatial patterns. The first principal component (PC1) can explain more than 90% of the total variance. With the second principal component (PC2), these two leading principal components can explain more than 99% of the total variance. The PC1 spectral features are consistent with spectral features due to the change of surface (or cloud deck) emission temperature. A couple of features can be clearly seen in the PC1 spatial map: ITCZ due to the low emission temperature of optically-thick high cloud, Sahara due to the high surface emission temperature and the clear sky. The spatial map of PC1 closely resembles that of NCEP/NCAR reanalysis of outgoing longwave radiation over the same period. It is also highly correlated with the map of high cloud amount. Both the spectral features and spatial map indicate that the PC1 is mainly due to the spatial variation of cloud emission temperature (for grid boxes with the optically thick clouds) and surface temperature. The PC2 shows spectral features similar to those due to the change of the optical depth of low clouds. Moreover, the PC2 spatial map shows maxima near the coasts of Peru, Namibia and California, as well as over the southern ocean west of Australia. All these regions are known for high frequency of marine stratus. Unlike the traditional approach of observing low clouds from the visible reflectance, these results indicate that we can actually see

  14. 3D Spatial and Spectral Fusion of Terrestrial Hyperspectral Imagery and Lidar for Hyperspectral Image Shadow Restoration Applied to a Geologic Outcrop

    NASA Astrophysics Data System (ADS)

    Hartzell, P. J.; Glennie, C. L.; Hauser, D. L.; Okyay, U.; Khan, S.; Finnegan, D. C.

    2016-12-01

    Recent advances in remote sensing technology have expanded the acquisition and fusion of active lidar and passive hyperspectral imagery (HSI) from an exclusively airborne technique to terrestrial modalities. This enables high resolution 3D spatial and spectral quantification of vertical geologic structures for applications such as virtual 3D rock outcrop models for hydrocarbon reservoir analog analysis and mineral quantification in open pit mining environments. In contrast to airborne observation geometry, the vertical surfaces observed by horizontal-viewing terrestrial HSI sensors are prone to extensive topography-induced solar shadowing, which leads to reduced pixel classification accuracy or outright removal of shadowed pixels from analysis tasks. Using a precisely calibrated and registered offset cylindrical linear array camera model, we demonstrate the use of 3D lidar data for sub-pixel HSI shadow detection and the restoration of the shadowed pixel spectra via empirical methods that utilize illuminated and shadowed pixels of similar material composition. We further introduce a new HSI shadow restoration technique that leverages collocated backscattered lidar intensity, which is resistant to solar conditions, obtained by projecting the 3D lidar points through the HSI camera model into HSI pixel space. Using ratios derived from the overlapping lidar laser and HSI wavelengths, restored shadow pixel spectra are approximated using a simple scale factor. Simulations of multiple lidar wavelengths, i.e., multi-spectral lidar, indicate the potential for robust HSI spectral restoration that is independent of the complexity and costs associated with rigorous radiometric transfer models, which have yet to be developed for horizontal-viewing terrestrial HSI sensors. The spectral restoration performance is quantified through HSI pixel classification consistency between full sun and partial sun exposures of a single geologic outcrop.

  15. Radiometric calibration of the telescope and ultraviolet spectrometer SUMER on SOHO

    NASA Astrophysics Data System (ADS)

    Hollandt, Jörg; Schühle, Udo; Paustian, Wolfgang; Curdt, Werner; Kühne, Michael; Wende, Burkhard; Wilhelm, Klaus

    1996-09-01

    The prelaunch spectral-sensitivity calibration of the solar spectrometer SUMER (Solar Ultraviolet Measurements of Emitted Radiation) is described. SUMER is part of the payload of the Solar and Heliospheric Observatory (SOHO), which begins its scientific mission in 1996. The instrument consists of a telescope and a spectrometer capable of taking spatially and spectrally highly resolved images of the Sun in a spectral range from 50 to 161 nm. The pointing capabilities, the dynamic range, and the sensitivity of the instrument allow measurements both on the solar disk and above the limb as great as two solar radii. To determine plasma temperatures and densities in the solar atmosphere, the instrument needs an absolute spectral-sensitivity calibration. Here we describe the prelaunch calibration of the full instrument, which utilizes a radiometric transfer-standard source. The transfer standard was based on a high-current hollow-cathode discharge source. It had been calibrated in the laboratory for vacuum UV radiometry of the Physikalisch-Technische Bundesanstalt by use of the calculable spectral photon flux of the Berlin electron storage ring for synchrotron radiation (BESSY)-a primary radiometric source standard.

  16. Hyperspectral Region Classification Using Three-Dimensional Spectral/Spatial Gabor Filters

    NASA Astrophysics Data System (ADS)

    Bau, Tien Cheng

    A three-dimensional (3D) spectral/spatial DFT can be used to represent a hyperspectral image region using a dense sampling in the frequency domain. In many cases, a more compact frequency-domain representation that preserves the three-dimensional structure of the data can be exploited. For this purpose, we have developed a new model for spectral/spatial information based on 3D Gabor filters. These filters capture specific orientation, scale, and wavelength-dependent properties of hyperspectral image data and provide an efficient means of sampling a three-dimensional frequency-domain representation. Since 3D Gabor filters allow for a large number of spectral/spatial features to be used to represent an image region, the performance and efficiency of algorithms that use this representation can be further improved if methods are available to reduce the size of the model. Thus, we have derived methods for selecting features that emphasize the most significant spectral/spatial differences for a set of classes. In addition, the orientation and scale selective properties of the filters allow the development of new algorithms that are invariant to rotation and scale. The new approach can also adapt to changes in the environmental conditions. The analysis of 3D textures under changing environmental conditions is addressed using an invariant recognition algorithm. The new features are compared against pure spectral features and multiband generalizations of gray-level co-occurrence matrix (GLCM) features using both synthesized and real-world data. We have demonstrated that the 3D Gabor features can be used to improve the classification of hyperspectral regions over using only spectral features.

  17. Application of spatial features to satellite land-use analysis. [spectral signature variations

    NASA Technical Reports Server (NTRS)

    Smith, J.; Hornung, R.; Berry, J.

    1975-01-01

    A Level I land-use analysis of selected training areas of the Colorado Front Range was carried out using digital ERTS-A satellite imagery. Level I land-use categories included urban, agriculture (irrigated and dryland farming), rangeland, and forests. The spatial variations in spectral response for these land-use classes were analyzed using discrete two-dimensional Fourier transforms to isolate and extract spatial features. Analysis was performed on ERTS frame 1352-17134 (July 10, 1973) and frame number 1388-17131 (August 15, 1973). On training sets, spatial features yielded 80 to 100 percent classification accuracies with commission errors ranging from 0 to 20 percent.

  18. Application of spatial features to satellite land-use analysis. [spectral signature variations

    NASA Technical Reports Server (NTRS)

    Smith, J.; Hornung, R.; Berry, J.

    1975-01-01

    A Level I land-use analysis of selected training areas of the Colorado Front Range was carried out using digital ERTS-A satellite imagery. Level I land-use categories included urban, agriculture (irrigated and dryland farming), rangeland, and forests. The spatial variations in spectral response for these land-use classes were analyzed using discrete two-dimensional Fourier transforms to isolate and extract spatial features. Analysis was performed on ERTS frame 1352-17134 (July 10, 1973) and frame number 1388-17131 (August 15, 1973). On training sets, spatial features yielded 80 to 100 percent classification accuracies with commission errors ranging from 0 to 20 percent.

  19. Importance of spatial and spectral data reduction in the detection of internal defects in food products.

    PubMed

    Zhang, Xuechen; Nansen, Christian; Aryamanesh, Nader; Yan, Guijun; Boussaid, Farid

    2015-04-01

    Despite the importance of data reduction as part of the processing of reflection-based classifications, this study represents one of the first in which the effects of both spatial and spectral data reductions on classification accuracies are quantified. Furthermore, the effects of approaches to data reduction were quantified for two separate classification methods, linear discriminant analysis (LDA) and support vector machine (SVM). As the model dataset, reflection data were acquired using a hyperspectral camera in 230 spectral channels from 401 to 879 nm (spectral resolution of 2.1 nm) from field pea (Pisum sativum) samples with and without internal pea weevil (Bruchus pisorum) infestation. We deployed five levels of spatial data reduction (binning) and eight levels of spectral data reduction (40 datasets). Forward stepwise LDA was used to select and include only spectral channels contributing the most to the separation of pixels from non-infested and infested field peas. Classification accuracies obtained with LDA and SVM were based on the classification of independent validation datasets. Overall, SVMs had significantly higher classification accuracies than LDAs (P < 0.01). There was a negative association between pixel resolution and classification accuracy, while spectral binning equivalent to up to 98% data reduction had negligible effect on classification accuracies. This study supports the potential use of reflection-based technologies in the quality control of food products with internal defects, and it highlights that spatial and spectral data reductions can (1) improve classification accuracies, (2) vastly decrease computer constraints, and (3) reduce analytical concerns associated with classifications of large and high-dimensional datasets.

  20. Infrared radiometric technique in temperature measurement

    NASA Technical Reports Server (NTRS)

    Glazer, S.; Madding, R.

    1988-01-01

    One class of commercially available imaging infrared radiometers using cooled detectors is sensitive to radiation over the 3 to 12 micron wavelength band. Spectral filters can tailor instrument sensitivity to specific regions where the target exhibits optimum radiance. The broadband spectral response coupled with real time two-dimensional imaging and emittance/background temperature corrections make the instruments useful for remote measurement of surface temperatures from -20 C to +1500 C. Commonly used radiometric techniques and assumptions are discussed, and performance specifications for a typical modern commercial instrument are presented. The potential usefulness of an imaging infrared radiometer in space laboratories is highlighted through examples of research, nondestructive evaluation, safety, and routine maintenance applications. Future improvements in instrument design and application of the radiometric technique are discussed.

  1. Simultaneous iterative reconstruction technique software for spectral-spatial EPR imaging

    NASA Astrophysics Data System (ADS)

    Spitzbarth, Martin; Drescher, Malte

    2015-08-01

    Continuous wave electron paramagnetic resonance imaging (EPRI) experiments often suffer from low signal to noise ratio. The increase in spectrometer time required to acquire data of sufficient quality to allow further analysis can be counteracted in part by more processing effort during the image reconstruction step. We suggest a simultaneous iterative reconstruction algorithm (SIRT) for reconstruction of continuous wave EPRI experimental data as an alternative to the widely applied filtered back projection algorithm (FBP). We show experimental and numerical test data of 2d spatial images and spectral-spatial images. We find that for low signal to noise ratio and spectral-spatial images that are limited by the maximum magnetic field gradient strength SIRT is more suitable than FBP.

  2. Temporal and spatial variation of canopy spectral characteristics in apple orchard

    NASA Astrophysics Data System (ADS)

    Deng, Xiaolei; Li, Minzan; Zheng, Lihua; Zhang, Yao; An, Xiaofei

    2012-11-01

    Plant nutritional status can be evaluated with remote sensing. In order to detect the temporal and spatial variation of spectral characteristics in apple orchard, the experiments were carried out. Firstly the flower/ leaf samples from 15 year-on trees and 5 year-off t rees were collected. The real time reflectance spectra of flowers/leaves from three parts (base, middle, top) of each main branch were measured by using the ASD spectrometer. And then the temporal and spatial variations of spectral characteristics were analyzed. The results showed that leaves from the top of the branch had higher reflectance than the other parts of the branch at the same time. The reflectance spectra of apple trees changed significantly at different stages. Furthermore, the reflectance spectra varied in different parts of the apple trees as well as in different trees. Accordingly the temporal curve and spatial figure were obtained and the growing informat ion can be analyzed from them.

  3. Bobcat 2013: a hyperspectral data collection supporting the development and evaluation of spatial-spectral algorithms

    NASA Astrophysics Data System (ADS)

    Kaufman, Jason; Celenk, Mehmet; White, A. K.; Stocker, Alan D.

    2014-06-01

    The amount of hyperspectral imagery (HSI) data currently available is relatively small compared to other imaging modalities, and what is suitable for developing, testing, and evaluating spatial-spectral algorithms is virtually nonexistent. In this work, a significant amount of coincident airborne hyperspectral and high spatial resolution panchromatic imagery that supports the advancement of spatial-spectral feature extraction algorithms was collected to address this need. The imagery was collected in April 2013 for Ohio University by the Civil Air Patrol, with their Airborne Real-time Cueing Hyperspectral Enhanced Reconnaissance (ARCHER) sensor. The target materials, shapes, and movements throughout the collection area were chosen such that evaluation of change detection algorithms, atmospheric compensation techniques, image fusion methods, and material detection and identification algorithms is possible. This paper describes the collection plan, data acquisition, and initial analysis of the collected imagery.

  4. A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching

    PubMed Central

    Mei, Xiaoguang; Ma, Yong; Li, Chang; Fan, Fan; Huang, Jun; Ma, Jiayi

    2015-01-01

    The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for infrared ultra-spectral signature classification via spatial pyramid matching (SPM), which includes two aspects. First, we introduce an infrared ultra-spectral signature similarity measure method via SPM, which is the foundation of the matching-based classification method. Second, we propose the classification method with reference spectral libraries, which utilizes the SPM-based similarity for the real-time infrared ultra-spectral signature classification with robustness performance. Specifically, instead of matching with each spectrum in the spectral library, our method is based on feature matching, which includes a feature library-generating phase. We calculate the SPM-based similarity between the feature of the spectrum and that of each spectrum of the reference feature library, then take the class index of the corresponding spectrum having the maximum similarity as the final result. Experimental comparisons on two publicly-available datasets demonstrate that the proposed method effectively improves the real-time classification performance and robustness to noise. PMID:26205263

  5. A Real-Time Infrared Ultra-Spectral Signature Classification Method via Spatial Pyramid Matching.

    PubMed

    Mei, Xiaoguang; Ma, Yong; Li, Chang; Fan, Fan; Huang, Jun; Ma, Jiayi

    2015-07-03

    The state-of-the-art ultra-spectral sensor technology brings new hope for high precision applications due to its high spectral resolution. However, it also comes with new challenges, such as the high data dimension and noise problems. In this paper, we propose a real-time method for infrared ultra-spectral signature classification via spatial pyramid matching (SPM), which includes two aspects. First, we introduce an infrared ultra-spectral signature similarity measure method via SPM, which is the foundation of the matching-based classification method. Second, we propose the classification method with reference spectral libraries, which utilizes the SPM-based similarity for the real-time infrared ultra-spectral signature classification with robustness performance. Specifically, instead of matching with each spectrum in the spectral library, our method is based on feature matching, which includes a feature library-generating phase. We calculate the SPM-based similarity between the feature of the spectrum and that of each spectrum of the reference feature library, then take the class index of the corresponding spectrum having the maximum similarity as the final result. Experimental comparisons on two publicly-available datasets demonstrate that the proposed method effectively improves the real-time classification performance and robustness to noise.

  6. Evaluation of atmospheric correction procedures for ocean color data processing using hyper- and multi-spectral radiometric measurements from the Long Island Sound Coastal Observatory

    NASA Astrophysics Data System (ADS)

    Ahmed, S.; Gilerson, A.; Harmel, T.; Hlaing, S.; Tonizzo, A.; Weidemann, A.; Arnone, R.

    2012-06-01

    In Ocean Color (OC) data processing one of the most critical steps is the atmospheric correction procedure used to separate the water leaving radiance, which contains information on water constituents, from the total radiance measured by space borne sensors, which contains atmospheric contributions. To ensure reliability of retrieved water leaving radiance values, and OC information derived from them, the quality of the atmospheric correction procedures applied needs to be assessed and validated. In this regard, the Long Island Sound Coastal Observatory (LISCO), jointly established by the City College of New York and the Naval Research Laboratory is becoming one of the key elements for OC sensors validation efforts, in part because of its capabilities for co-located hyper and multi-spectral measurements using HyperSAS and SeaPRISM radiometers respectively, with the latter being part of the NASA AERONET - OC network. Accordingly, the impact of the procedures used for atmospheric correction on the retrieval of remote sensing reflectance (Rrs) data can then be evaluated based on satellite OC data acquired from the LISCO site over the last two years. From this, the qualities of atmospheric correction procedures are assessed by performing matchup comparisons between the satellites retrieved atmospheric data and that of LISCO.

  7. Intraband radiometric performance of the Landsat Thematic Mappers.

    USGS Publications Warehouse

    Kieffer, H.H.; Cook, D.A.; Eliason, E.M.; Eliason, P.T.

    1985-01-01

    Radiometric characteristics have been examined of the Landsat-4 and Landsat-5 Thematic Mappers (TMs) that can be established without absolute calibration of spectral data. This analysis is based on radiometrically and geometrically raw (B-type) data of both uniform (flat-field) and high-contrast scenes. Subscenes selected for uniform radiance were used to characterized subtle radiometric differences and noise problems. Although the general performance of the Thematic Mappers is excellent, various anomalies that have a magnitude of a few digital levels (DN) or less are quantified. -from Authors

  8. Radiometric cloud imaging with an uncooled microbolometer thermal infrared camera.

    PubMed

    Shaw, Joseph; Nugent, Paul; Pust, Nathan; Thurairajah, Brentha; Mizutani, Kohei

    2005-07-25

    An uncooled microbolometer-array thermal infrared camera has been incorporated into a remote sensing system for radiometric sky imaging. The radiometric calibration is validated and improved through direct comparison with spectrally integrated data from the Atmospheric Emitted Radiance Interferometer (AERI). With the improved calibration, the Infrared Cloud Imager (ICI) system routinely obtains sky images with radiometric uncertainty less than 0.5 W/(m(2 )sr) for extended deployments in challenging field environments. We demonstrate the infrared cloud imaging technique with still and time-lapse imagery of clear and cloudy skies, including stratus, cirrus, and wave clouds.

  9. Reduction of Radiometric Miscalibration—Applications to Pushbroom Sensors

    PubMed Central

    Rogaß, Christian; Spengler, Daniel; Bochow, Mathias; Segl, Karl; Lausch, Angela; Doktor, Daniel; Roessner, Sigrid; Behling, Robert; Wetzel, Hans-Ulrich; Kaufmann, Hermann

    2011-01-01

    The analysis of hyperspectral images is an important task in Remote Sensing. Foregoing radiometric calibration results in the assignment of incident electromagnetic radiation to digital numbers and reduces the striping caused by slightly different responses of the pixel detectors. However, due to uncertainties in the calibration some striping remains. This publication presents a new reduction framework that efficiently reduces linear and nonlinear miscalibrations by an image-driven, radiometric recalibration and rescaling. The proposed framework—Reduction Of Miscalibration Effects (ROME)—considering spectral and spatial probability distributions, is constrained by specific minimisation and maximisation principles and incorporates image processing techniques such as Minkowski metrics and convolution. To objectively evaluate the performance of the new approach, the technique was applied to a variety of commonly used image examples and to one simulated and miscalibrated EnMAP (Environmental Mapping and Analysis Program) scene. Other examples consist of miscalibrated AISA/Eagle VNIR (Visible and Near Infrared) and Hawk SWIR (Short Wave Infrared) scenes of rural areas of the region Fichtwald in Germany and Hyperion scenes of the Jalal-Abad district in Southern Kyrgyzstan. Recovery rates of approximately 97% for linear and approximately 94% for nonlinear miscalibrated data were achieved, clearly demonstrating the benefits of the new approach and its potential for broad applicability to miscalibrated pushbroom sensor data. PMID:22163960

  10. Reduction of radiometric miscalibration--applications to pushbroom sensors.

    PubMed

    Rogass, Christian; Spengler, Daniel; Bochow, Mathias; Segl, Karl; Lausch, Angela; Doktor, Daniel; Roessner, Sigrid; Behling, Robert; Wetzel, Hans-Ulrich; Kaufmann, Hermann

    2011-01-01

    The analysis of hyperspectral images is an important task in Remote Sensing. Foregoing radiometric calibration results in the assignment of incident electromagnetic radiation to digital numbers and reduces the striping caused by slightly different responses of the pixel detectors. However, due to uncertainties in the calibration some striping remains. This publication presents a new reduction framework that efficiently reduces linear and nonlinear miscalibrations by an image-driven, radiometric recalibration and rescaling. The proposed framework-Reduction Of Miscalibration Effects (ROME)-considering spectral and spatial probability distributions, is constrained by specific minimisation and maximisation principles and incorporates image processing techniques such as Minkowski metrics and convolution. To objectively evaluate the performance of the new approach, the technique was applied to a variety of commonly used image examples and to one simulated and miscalibrated EnMAP (Environmental Mapping and Analysis Program) scene. Other examples consist of miscalibrated AISA/Eagle VNIR (Visible and Near Infrared) and Hawk SWIR (Short Wave Infrared) scenes of rural areas of the region Fichtwald in Germany and Hyperion scenes of the Jalal-Abad district in Southern Kyrgyzstan. Recovery rates of approximately 97% for linear and approximately 94% for nonlinear miscalibrated data were achieved, clearly demonstrating the benefits of the new approach and its potential for broad applicability to miscalibrated pushbroom sensor data.

  11. Extending the effective imaging depth in spectral domain optical coherence tomography by dual spatial frequency encoding

    NASA Astrophysics Data System (ADS)

    Wu, Tong; Wang, Qingqing; Liu, Youwen; Wang, Jiming

    2016-03-01

    We present a spatial frequency domain multiplexing method for extending the imaging depth range of a SDOCT system without any expensive device. This method uses two reference arms with different round-trip optical delay to probe different depth regions within the sample. Two galvo scanners with different pivot-offset distances in the reference arms are used for spatial frequency modulation and multiplexing. While simultaneously driving the galvo scanners in the reference arms and the sample arm, the spatial spectrum of the acquired two-dimensional OCT spectral interferogram corresponding to the shallow and deep depth of the sample will be shifted to the different frequency bands in the spatial frequency domain. After data filtering, image reconstruction and fusion the spatial frequency multiplexing SDOCT system can provide an approximately 1.9 fold increase in the effective ranging depth compared with that of a conventional single-reference-arm full-range SDOCT system.

  12. Radiometric Dating Does Work!

    ERIC Educational Resources Information Center

    Dalrymple, G. Brent

    2000-01-01

    Discusses the accuracy of dating methods and creationist arguments that radiometric dating does not work. Explains the Manson meteorite impact and the Pierre shale, the ages of meteorites, the K-T tektites, and dating the Mount Vesuvius eruption. (Author/YDS)

  13. Radiometric Dating Does Work!

    ERIC Educational Resources Information Center

    Dalrymple, G. Brent

    2000-01-01

    Discusses the accuracy of dating methods and creationist arguments that radiometric dating does not work. Explains the Manson meteorite impact and the Pierre shale, the ages of meteorites, the K-T tektites, and dating the Mount Vesuvius eruption. (Author/YDS)

  14. Photovoltaics radiometric issues and needs

    SciTech Connect

    Myers, D.R.

    1995-11-01

    This paper presents a summary of issues discussed at the photovoltaic radiometric measurements workshop. Topics included radiometric measurements guides, the need for well-defined goals, documentation, calibration checks, accreditation of testing laboratories and methods, the need for less expensive radiometric instrumentation, data correlations, and quality assurance.

  15. Cross-Calibration between ASTER and MODIS Visible to Near-Infrared Bands for Improvement of ASTER Radiometric Calibration

    PubMed Central

    Tsuchida, Satoshi; Thome, Kurtis

    2017-01-01

    Radiometric cross-calibration between the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) has been partially used to derive the ASTER radiometric calibration coefficient (RCC) curve as a function of date on visible to near-infrared bands. However, cross-calibration is not sufficiently accurate, since the effects of the differences in the sensor’s spectral and spatial responses are not fully mitigated. The present study attempts to evaluate radiometric consistency across two sensors using an improved cross-calibration algorithm to address the spectral and spatial effects and derive cross-calibration-based RCCs, which increases the ASTER calibration accuracy. Overall, radiances measured with ASTER bands 1 and 2 are on averages 3.9% and 3.6% greater than the ones measured on the same scene with their MODIS counterparts and ASTER band 3N (nadir) is 0.6% smaller than its MODIS counterpart in current radiance/reflectance products. The percentage root mean squared errors (%RMSEs) between the radiances of two sensors are 3.7, 4.2, and 2.3 for ASTER band 1, 2, and 3N, respectively, which are slightly greater or smaller than the required ASTER radiometric calibration accuracy (4%). The uncertainty of the cross-calibration is analyzed by elaborating the error budget table to evaluate the International System of Units (SI)-traceability of the results. The use of the derived RCCs will allow further reduction of errors in ASTER radiometric calibration and subsequently improve interoperability across sensors for synergistic applications. PMID:28777329

  16. Spectral and spatial decomposition of lithospheric magnetic field models using spherical Slepian functions

    NASA Astrophysics Data System (ADS)

    Beggan, Ciarán D.; Saarimäki, Jarno; Whaler, Kathryn A.; Simons, Frederik J.

    2013-04-01

    Global magnetic field models are typically expressed as spherical-harmonic expansion coefficients. Slepian functions are linear combinations of spherical harmonics that produce new basis functions, which vanish approximately outside chosen geographical boundaries but also remain orthogonal within the spatial region of interest. Hence, they are suitable for decomposing spherical-harmonic models into portions that have significant magnetic field strength only in selected areas. Slepian functions are spatio-spectrally concentrated, balancing spatial bias and spectral leakage. Here, we employ them as a basis to decompose the global lithospheric magnetic field model MF7 up to degree and order 72, into two distinct regions. One of the resultant fields is concentrated within the ensemble of continental domains, and the other is localized over its complement, the oceans. Our procedure neatly divides the spectral power at each harmonic degree into two parts. The field over the continents dominates the overall crustal magnetic field, and each region has a distinct power-spectral signature. The oceanic power spectrum is approximately flat, while that of the continental region shows increasing power as the spherical-harmonic degree increases. We provide a further breakdown of the field into smaller, non-overlapping continental and oceanic regions, and speculate on the source of the variability in their spectral signatures.

  17. A combined spatial-spectral method for automated white blood cells segmentation

    NASA Astrophysics Data System (ADS)

    Li, Qingli; Wang, Yiting; Liu, Hongying; Wang, Jianbiao; Guo, Fangmin

    2013-12-01

    To overcome the shortcomings in the traditional white blood cells (WBCs) identification methods based on the color or gray images captured by light microscopy, a microscopy hyperspectral imaging system was used to analyze the blood smears. The system was developed by coupling an acousto-optic tunable filter (AOTF) adapter to a microscopy and driven by a SPF Model AOTF controller, which can capture hyperspectral images from 550 nm to 1000 nm with the spectral resolution 2-5 nm. Moreover, a combined spatial-spectral algorithm is proposed to segment the nuclei and cytoplasm of WBCs from the microscopy hyperspectral images. The proposed algorithm is based on the pixel-wise improved spectral angle mapper (ISAM) segmentation, followed by the majority voting within the active contour model regions. Experimental results show that the accuracy of the proposed algorithm is 91.06% (nuclei) and 85.59% (cytoplasm), respectively, which is higher than that of the spectral information divergence (SID) algorithm because the new method can jointly use both the spectral and spatial information of blood cells.

  18. A Weighted Spatial-Spectral Kernel RX Algorithm and Efficient Implementation on GPUs

    PubMed Central

    Zhao, Chunhui; Li, Jiawei; Meng, Meiling; Yao, Xifeng

    2017-01-01

    The kernel RX (KRX) detector proposed by Kwon and Nasrabadi exploits a kernel function to obtain a better detection performance. However, it still has two limits that can be improved. On the one hand, reasonable integration of spatial-spectral information can be used to further improve its detection accuracy. On the other hand, parallel computing can be used to reduce the processing time in available KRX detectors. Accordingly, this paper presents a novel weighted spatial-spectral kernel RX (WSSKRX) detector and its parallel implementation on graphics processing units (GPUs). The WSSKRX utilizes the spatial neighborhood resources to reconstruct the testing pixels by introducing a spectral factor and a spatial window, thereby effectively reducing the interference of background noise. Then, the kernel function is redesigned as a mapping trick in a KRX detector to implement the anomaly detection. In addition, a powerful architecture based on the GPU technique is designed to accelerate WSSKRX. To substantiate the performance of the proposed algorithm, both synthetic and real data are conducted for experiments. PMID:28241511

  19. A Weighted Spatial-Spectral Kernel RX Algorithm and Efficient Implementation on GPUs.

    PubMed

    Zhao, Chunhui; Li, Jiawei; Meng, Meiling; Yao, Xifeng

    2017-02-23

    The kernel RX (KRX) detector proposed by Kwon and Nasrabadi exploits a kernel function to obtain a better detection performance. However, it still has two limits that can be improved. On the one hand, reasonable integration of spatial-spectral information can be used to further improve its detection accuracy. On the other hand, parallel computing can be used to reduce the processing time in available KRX detectors. Accordingly, this paper presents a novel weighted spatial-spectral kernel RX (WSSKRX) detector and its parallel implementation on graphics processing units (GPUs). The WSSKRX utilizes the spatial neighborhood resources to reconstruct the testing pixels by introducing a spectral factor and a spatial window, thereby effectively reducing the interference of background noise. Then, the kernel function is redesigned as a mapping trick in a KRX detector to implement the anomaly detection. In addition, a powerful architecture based on the GPU technique is designed to accelerate WSSKRX. To substantiate the performance of the proposed algorithm, both synthetic and real data are conducted for experiments.

  20. Detection of the power lines in UAV remote sensed images using spectral-spatial methods.

    PubMed

    Bhola, Rishav; Krishna, Nandigam Hari; Ramesh, K N; Senthilnath, J; Anand, Gautham

    2017-09-17

    In this paper, detection of the power lines on images acquired by Unmanned Aerial Vehicle (UAV) based remote sensing is carried out using spectral-spatial methods. Spectral clustering was performed using Kmeans and Expectation Maximization (EM) algorithm to classify the pixels into the power lines and non-power lines. The spectral clustering methods used in this study are parametric in nature, to automate the number of clusters Davies-Bouldin index (DBI) is used. The UAV remote sensed image is clustered into the number of clusters determined by DBI. The k clustered image is merged into 2 clusters (power lines and non-power lines). Further, spatial segmentation was performed using morphological and geometric operations, to eliminate the non-power line regions. In this study, UAV images acquired at different altitudes and angles were analyzed to validate the robustness of the proposed method. It was observed that the EM with spatial segmentation (EM-Seg) performed better than the Kmeans with spatial segmentation (Kmeans-Seg) on most of the UAV images. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The Next Step in Ice Flow Measurement from Optical Imagery: Comprehensive Mapping Of Ice Sheet Flow in Landsat 8 Imagery Using Spatial Frequency Filtering, Enabled by High Radiometric Sensitivity

    NASA Astrophysics Data System (ADS)

    Fahnestock, M. A.; Scambos, T. A.; Klinger, M. J.

    2014-12-01

    The advent of large area satellite coverage in the visible spectrum enabled satellite-based tracking of ice sheet flow just over twenty years ago. Following this, rapid development of techniques for imaging radar data enabled the wide-area mapping and time series coverage that SAR has brought to the documentation of changing ice discharge. We report on the maturation of feature tracking in visible-band satellite imagery of the ice sheets enabled by the high radiometric resolution and accurate geolocation delivered by Landsat 8, and apply this to mapping ice flow in the interiors of Antarctica and Greenland. The high radiometric resolution of Landsat 8 enables one to track subtle patterns on the surface of the ice sheet, unique at spatial scales of a few hundred meters, between images separated by multiple orbit cycles. In areas with significant dynamic topography generated by ice flow, this requires use of simple spatial filtering techniques first applied by Scambos et al. 1992. The result is densely sampled maps of surface motion that begin to rival the coverage available from SAR speckle tracking and interferometry. Displacement accuracy can approach one tenth of a pixel for reasonable chip sizes using conventional normalized cross-correlation; this can exceed the geolocation accuracy of the scenes involved, but coverage is sufficient to allow correction strategies based on very slow moving ice. The advance in radiometry, geo-location, and tracking tools is augmented by an increased rate of acquisition by Landsat 8. This helps mitigate the issue of cloud cover, as much of every 16-day orbit cycle over ice is acquired, maximizing the acquisition of clear-sky scenes. Using the correlation techniques common to IMCORR and later software, modern libraries, and single-cpu hardware, we are able to process full Landsat 8 scene pairs in a few minutes, allowing comprehensive analysis of ~1K available ice sheet image pairs in a few days.

  2. Radiometric Characterization of IKONOS Multispectral Imagery

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Ryan, Robert E.; Kelly, Michelle; Holekamp, Kara; Zanoni, Vicki; Thome, Kurtis; Schiller, Stephen

    2002-01-01

    A radiometric characterization of Space Imaging's IKONOS 4-m multispectral imagery has been performed by a NASA funded team from the John C. Stennis Space Center (SSC), the University of Arizona Remote Sensing Group (UARSG), and South Dakota State University (SDSU). Both intrinsic radiometry and the effects of Space Imaging processing on radiometry were investigated. Relative radiometry was examined with uniform Antarctic and Saharan sites. Absolute radiometric calibration was performed using reflectance-based vicarious calibration methods on several uniform sites imaged by IKONOS, coincident with ground-based surface and atmospheric measurements. Ground-based data and the IKONOS spectral response function served as input to radiative transfer codes to generate a Top-of-Atmosphere radiance estimate. Calibration coefficients derived from each vicarious calibration were combined to generate an IKONOS radiometric gain coefficient for each multispectral band assuming a linear response over the full dynamic range of the instrument. These calibration coefficients were made available to Space Imaging, which subsequently adopted them by updating its initial set of calibration coefficients. IKONOS imagery procured through the NASA Scientific Data Purchase program is processed with or without a Modulation Transfer Function Compensation kernel. The radiometric effects of this kernel on various scene types was also investigated. All imagery characterized was procured through the NASA Scientific Data Purchase program.

  3. Fast Multispectral Imaging by Spatial Pixel-Binning and Spectral Unmixing.

    PubMed

    Pan, Zhi-Wei; Shen, Hui-Liang; Li, Chunguang; Chen, Shu-Jie; Xin, John H

    2016-08-01

    Multispectral imaging system is of wide application in relevant fields for its capability in acquiring spectral information of scenes. Its limitation is that, due to the large number of spectral channels, the imaging process can be quite time-consuming when capturing high-resolution (HR) multispectral images. To resolve this limitation, this paper proposes a fast multispectral imaging framework based on the image sensor pixel-binning and spectral unmixing techniques. The framework comprises a fast imaging stage and a computational reconstruction stage. In the imaging stage, only a few spectral images are acquired in HR, while most spectral images are acquired in low resolution (LR). The LR images are captured by applying pixel binning on the image sensor, such that the exposure time can be greatly reduced. In the reconstruction stage, an optimal number of basis spectra are computed and the signal-dependent noise statistics are estimated. Then the unknown HR images are efficiently reconstructed by solving a closed-form cost function that models the spatial and spectral degradations. The effectiveness of the proposed framework is evaluated using real-scene multispectral images. Experimental results validate that, in general, the method outperforms the state of the arts in terms of reconstruction accuracy, with additional 20× or more improvement in computational efficiency.

  4. Comparison of spatial variability in visible and near-infrared spectral images

    USGS Publications Warehouse

    Chavez, P.S.

    1992-01-01

    The visible and near-infrared bands of the Landsat Thematic Mapper (TM) and the Satellite Pour l'Observation de la Terre (SPOT) were analyzed to determine which band contained more spatial variability. It is important for applications that require spatial information, such as those dealing with mapping linear features and automatic image-to-image correlation, to know which spectral band image should be used. Statistical and visual analyses were used in the project. The amount of variance in an 11 by 11 pixel spatial filter and in the first difference at the six spacings of 1, 5, 11, 23, 47, and 95 pixels was computed for the visible and near-infrared bands. The results indicate that the near-infrared band has more spatial variability than the visible band, especially in images covering densely vegetated areas. -Author

  5. Experimental Estimation of CLASP Spatial and Spectral Resolutions: Results of the Instrument's Optical Alignment

    NASA Technical Reports Server (NTRS)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Bando, T.; Kano, R.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchere, F.

    2015-01-01

    The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket experiment design to measure for the first time the polarization signal of the Lyman-Alpha line (121.6nm), emitted in the solar upper-chromosphere and transition region. This instrument aims to detect the Hanle effect's signature hidden in the Ly-alpha polarization, as a tool to probe the chromospheric magnetic field. Hence, an unprecedented polarization accuracy is needed ((is) less than 10 (exp -3). Nevertheless, spatial and spectral resolutions are also crucial to observe chhromospheric feature such as spicules, and to have precise measurement of the Ly-alpha line core and wings. Hence, this poster will present how the telescope and the spectrograph were separately aligned, and their combined spatial and spectral resolutions.

  6. Spatial and spectral coherence in propagating high-intensity twin beams.

    PubMed

    Haderka, Ondřej; Machulka, Radek; Peřina, Jan; Allevi, Alessia; Bondani, Maria

    2015-09-25

    Spatial and spectral coherence of high-intensity twin-beam states propagating from the near-field to the far-field configurations is experimentally investigated by measuring intensity auto- and cross-correlation functions. The experimental setup includes a moving crystal and an iCCD camera placed at the output plane of an imaging spectrometer. Evolution from the tight near-field spatial position cross-correlations to the far-field momentum cross-correlations, accompanied by changeless spectral cross-correlations, is observed. Intensity autocorrelation functions and beam profiles are also monitored as they provide the number of degrees of freedom constituting the down-converted beams. The strength of intensity cross-correlations as an alternative quantity for the determination of the number of degrees of freedom is also measured. The relation between the beam coherence and the number of degrees of freedom is discussed.

  7. The development of a spectral-spatial classifier for earth observational data

    NASA Technical Reports Server (NTRS)

    Landgrebe, D. A.

    1980-01-01

    Over the last several years a classifier for earth observational image data has been under development intended to achieve improved performance by utilizing spatial characteristics of the data as an adjunct to multispectral properties. The paper provides an overview of the conception, development, evaluation and documentation of this spectral-spatial classifier. The research program leading to this classifier is described, the algorithms of the current implementation called ECHO are outlined, and results on its performance are summarized. These results show improved accuracy, with greater computation efficiency, and only slightly increased operator complexity.

  8. Spatially-Coherent Non-Linear Dimensionality Reduction and Segmentation of Hyper-Spectral Images (PREPRINT)

    DTIC Science & Technology

    2006-06-01

    projection methods such as Principal Component Analysis ( PCA ) [16]. Methods like PCA , Factor analysis, and multidimensional scaling, assume that the...underlying data manifold is linear, which is not necessarily true in the case of hyper-spectral data and most imaging modalities. PCA has been shown not to...accurate classification and segmentation. This spatial coherence is introduced following recent results in the literature of image denoising and texture

  9. Optical Design for a Spatial-Spectral Volume Holographic Imaging System

    PubMed Central

    Gelsinger-Austin, Paul J.; Luo, Yuan; Watson, Jonathan M.; Kostuk, Raymond K.; Barbastathis, George; Barton, Jennifer K.; Castro, Jose M.

    2010-01-01

    Spatial Spectral Holographic imaging system (S2-VHIS) is a promising alternative to confocal microscopy due to its capabilities to simultaneously image several sample depths with high resolution. However, the field of view of previously presented S2-VHIS prototypes has been restricted to less than 200μm. This paper presents experimental results of an improved S2-VHIS design which have a field of view of ~1mm while maintaining high resolution and dynamic range. PMID:20664803

  10. Radiometric characterization of ultra-bright xenon short-arc discharge lamps for novel applications

    NASA Astrophysics Data System (ADS)

    Nakar, Doron; Malul, Asher; Feuermann, Daniel; Gordon, Jeffrey M.

    2007-09-01

    The latest generations of ultra-bright Xenon short-arc discharge lamps have prodigious emissions outside the visible spectrum, primarily in the near infrared. Their brightness distributions are spatially and angularly inhomogeneous due to both the pronounced non-uniformities of the plasma arc and the substantial infrared radiation from the hot electrodes. These characteristics are fortuitously favorable for applications in photonic surgery, biomedical diagnostics, high-temperature chemical reactors and furnaces: cases where the full lamp spectrum is utilizable, and the key is reconstituting the spectral power density of the optimal regions of the lamp's plasma at a remote target. The associated optical systems must be tailored to lamp radiometric properties that are not extensively available and invariably are restricted to visible light due to their widespread use in projection systems. We present experimental measurements for the spectral, spatial and angular distributions of 150 W lamps of this genre, and relate to their ramifications for broadband high-flux applications.

  11. A hybrid spatial-spectral denoising method for infrared hyperspectral images using 2DPCA

    NASA Astrophysics Data System (ADS)

    Huang, Jun; Ma, Yong; Mei, Xiaoguang; Fan, Fan

    2016-11-01

    The traditional noise reduction methods for 3-D infrared hyperspectral images typically operate independently in either the spatial or spectral domain, and such methods overlook the relationship between the two domains. To address this issue, we propose a hybrid spatial-spectral method in this paper to link both domains. First, principal component analysis and bivariate wavelet shrinkage are performed in the 2-D spatial domain. Second, 2-D principal component analysis transformation is conducted in the 1-D spectral domain to separate the basic components from detail ones. The energy distribution of noise is unaffected by orthogonal transformation; therefore, the signal-to-noise ratio of each component is used as a criterion to determine whether a component should be protected from over-denoising or denoised with certain 1-D denoising methods. This study implements the 1-D wavelet shrinking threshold method based on Stein's unbiased risk estimator, and the quantitative results on publicly available datasets demonstrate that our method can improve denoising performance more effectively than other state-of-the-art methods can.

  12. Hierarchical Sparse Learning with Spectral-Spatial Information for Hyperspectral Imagery Denoising

    PubMed Central

    Liu, Shuai; Jiao, Licheng; Yang, Shuyuan

    2016-01-01

    During the acquisition process hyperspectral images (HSI) are inevitably corrupted by various noises, which greatly influence their visual impression and subsequent applications. In this paper, a novel Bayesian approach integrating hierarchical sparse learning and spectral-spatial information is proposed for HSI denoising. Based on the structure correlations, spectral bands with similar and continuous features are segmented into the same band-subset. To exploit local similarity, each subset is then divided into overlapping cubic patches. All patches can be regarded as consisting of clean image component, Gaussian noise component and sparse noise component. The first term is depicted by a linear combination of dictionary elements, where Gaussian process with Gamma distribution is applied to impose spatial consistency on dictionary. The last two terms are utilized to fully depict the noise characteristics. Furthermore, the sparseness of the model is adaptively manifested through Beta-Bernoulli process. Calculated by Gibbs sampler, the proposed model can directly predict the noise and dictionary without priori information of the degraded HSI. The experimental results on both synthetic and real HSI demonstrate that the proposed approach can better suppress the existing various noises and preserve the structure/spectral-spatial information than the compared state-of-art approaches. PMID:27763511

  13. A new method for spatial resolution enhancement of hyperspectral images using sparse coding and linear spectral unmixing

    NASA Astrophysics Data System (ADS)

    Hashemi, Nezhad Z.; Karami, A.

    2015-10-01

    Hyperspectral images (HSI) have high spectral and low spatial resolutions. However, multispectral images (MSI) usually have low spectral and high spatial resolutions. In various applications HSI with high spectral and spatial resolutions are required. In this paper, a new method for spatial resolution enhancement of HSI using high resolution MSI based on sparse coding and linear spectral unmixing (SCLSU) is introduced. In the proposed method (SCLSU), high spectral resolution features of HSI and high spatial resolution features of MSI are fused. In this case, the sparse representation of some high resolution MSI and linear spectral unmixing (LSU) model of HSI and MSI is simultaneously used in order to construct high resolution HSI (HRHSI). The fusion process of HSI and MSI is formulated as an ill-posed inverse problem. It is solved by the Split Augmented Lagrangian Shrinkage Algorithm (SALSA) and an orthogonal matching pursuit (OMP) algorithm. Finally, the proposed algorithm is applied to the Hyperion and ALI datasets. Compared with the other state-of-the-art algorithms such as Coupled Nonnegative Matrix Factorization (CNMF) and local spectral unmixing, the SCLSU has significantly increased the spatial resolution and in addition the spectral content of HSI is well maintained.

  14. A Linear Spatial Spectral Mixture Model for the Improved Estimation of Subpixel Saltcedar Cover along the Forgotten River

    NASA Astrophysics Data System (ADS)

    Shi, C.; Wang, L.

    2015-12-01

    Spectral unmixing is the process of decomposing the measured spectrum of a mixed pixel into a set of pure spectral signatures called endmembers and their corresponding abundances indicating the fractional area coverage of each endmember present in the pixel. A substantial number of spectral unmixing studies rely on a spectral mixture model which assumes that spectral mixing only occurs within the extent of a pixel. However, due to adjacency effect, the spectral measurement of the pixel may be contaminated by spatial interactions from materials that are present in its spatial neighborhood. In this paper, a linear spatial spectral mixture model is developed to improve the accuracy of the estimated abundance of invasive saltcedar along the Forgotten River reach of the Rio Grande. A spatial weights matrix which specifies for each pixel the locations and the weights of its neighborhood set is used to summarize the spatial relationships among pixels in the Landsat data. A spatial lag operator, defined as a weighted average of the values at neighboring locations, is adopted as an expression of spectral contribution from nearby pixels and added to the classic linear mixture model. The fractional abundances are iteratively estimated using the alternating direction method of multipliers (ADMM) algorithm. With the incorporation of adjacency effect, RMSEs of the fractional cover of ground classes were reduced. The derived sub-pixel abundances of saltcedar are beneficial for ecological management.

  15. Laboratory Measurement of Bidirectional Reflectance of Radiometric Tarps

    NASA Technical Reports Server (NTRS)

    Knowlton, Kelly

    2006-01-01

    Objectives: a) To determine the magnitude of radiometric tarp BRDF; b) To determine whether an ASD FieldSpec Pro spectroradiometer can be used to perform the experiment. Radiometric tarps with nominal reflectance values of 52%, 35%, and 3.5%, deployed for IKONOS. QuickBird, and OrbView-3 overpasses Ground-based spectroradiometric measurements of tarp and Spectralon@ panel taken during overpass using ASD FieldSpec Pro spectroradiometer, and tarp reflectance calculated. Reflectance data used in atmospheric radiative transfer model (MODTRAN) to predict satellite at-sensor radiance for radiometric calibration. Reflectance data also used to validate atmospheric correction of high-spatial-resolution multispectral image products

  16. Maximum Linear-Phase Spectral-Spatial RF Pulses for Fat-Suppressed PRF-Shift MR Thermometry

    PubMed Central

    Grissom, William A; Kerr, Adam B; Holbrook, Andrew B; Pauly, John M; Butts-Pauly, Kim

    2009-01-01

    Conventional spectral-spatial pulses used for water-selective excitation in proton-resonance-frequency (PRF-) shift MR thermometry require increased sequence length, compared to shorter wideband pulses. This is because spectral-spatial pulses are longer than wideband pulses, and the TE period starts midway through them. Therefore, for a fixed TE, one must increase sequence length to accommodate conventional spectral-spatial pulses in PRF-shift thermometry. We introduce improved water-selective spectral-spatial pulses for which the TE period starts near the beginning of excitation. Instead of requiring increased sequence length, these pulses extend into the long TE periods common to PRF sequences. The new pulses therefore alleviate the traditional tradeoff between sequence length and fat suppression. We experimentally demonstrate an 11% improvement in frame rate in a PRF imaging sequence, compared to conventional spectral-spatial excitation. We also introduce a novel spectral-spatial pulse design technique that is a hybrid of previous model- and filter-based techniques, and that inherits advantages from both. We experimentally validate the pulses’ performance in suppressing lipid signal, and in reducing sequence length compared to conventional spectral-spatial pulses. PMID:19780177

  17. Measuring temporal, spectral and spatial changes in electrophysiological brain network connectivity.

    PubMed

    Brookes, Matthew J; O'Neill, George C; Hall, Emma L; Woolrich, Mark W; Baker, Adam; Palazzo Corner, Sofia; Robson, Siân E; Morris, Peter G; Barnes, Gareth R

    2014-05-01

    The topic of functional connectivity in neuroimaging is expanding rapidly and many studies now focus on coupling between spatially separate brain regions. These studies show that a relatively small number of large scale networks exist within the brain, and that healthy function of these networks is disrupted in many clinical populations. To date, the vast majority of studies probing connectivity employ techniques that compute time averaged correlation over several minutes, and between specific pre-defined brain locations. However, increasing evidence suggests that functional connectivity is non-stationary in time. Further, electrophysiological measurements show that connectivity is dependent on the frequency band of neural oscillations. It is also conceivable that networks exhibit a degree of spatial inhomogeneity, i.e. the large scale networks that we observe may result from the time average of multiple transiently synchronised sub-networks, each with their own spatial signature. This means that the next generation of neuroimaging tools to compute functional connectivity must account for spatial inhomogeneity, spectral non-uniformity and temporal non-stationarity. Here, we present a means to achieve this via application of windowed canonical correlation analysis (CCA) to source space projected MEG data. We describe the generation of time-frequency connectivity plots, showing the temporal and spectral distribution of coupling between brain regions. Moreover, CCA over voxels provides a means to assess spatial non-uniformity within short time-frequency windows. The feasibility of this technique is demonstrated in simulation and in a resting state MEG experiment where we elucidate multiple distinct spatio-temporal-spectral modes of covariation between the left and right sensorimotor areas. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Estimating and Mapping Urban Impervious Surfaces: Reflection on Spectral, Spatial, and Temporal Resolutions

    NASA Astrophysics Data System (ADS)

    Weng, Q.

    2007-12-01

    Impervious surface is a key indicator of urban environmental quality and urbanization degree. Therefore, estimation and mapping of impervious surfaces in urban areas has attracted more and more attention recently by using remote sensing digital images. In this paper, satellite images with various spectral, spatial, and temporal resolutions are employed to examine the effects of these remote sensing data characteristics on mapping accuracy of urban impervious surfaces. The study area was the city proper of Indianapolis (Marion County), Indiana, United States. Linear spectral mixture analysis was applied to generate high albedo, low albedo, vegetation, and soil fraction images (endmembers) from the satellite images, and impervious surfaces were then estimated by adding high albedo and low albedo fraction images. A comparison of EO-1 ALI (multispectral) and Hyperion (hyperspectral) images indicates that the Hyperion image was more effective in discerning low albedo surface materials, especially the spectral bands in the mid-infrared region. Linear spectral mixing modeling was found more useful for medium spatial resolution images, such as Landsat TM/ETM+ and ASTER images, due to the existence of a large amount of mixed pixels in the urban areas. The model, however, may not be suitable for high spatial resolution images, such as IKONOS images, because of less influence from the mixing pixel. The shadow problem in the high spatial resolution images, caused by tall buildings and large tree crowns, is a challenge in impervious surface extraction. Alternative image processing algorithms such as decision tree classifier may be more appropriate to achieve high mapping accuracy. For mid-latitude cities, seasonal vegetation phenology has a significant effect on the spectral response of terrestrial features, and therefore, image analysis must take into account of this environmental characteristic. Three ASTER images, acquired on April 5, 2004, June 16, 2001, and October 3, 2000

  19. Spatially uniform sampling in 4-D EPR spectral-spatial imaging

    NASA Astrophysics Data System (ADS)

    Ahn, Kang-Hyun; Halpern, Howard J.

    2007-03-01

    Four-dimensional EPR imaging involves a computationally intensive inversion of the sampled Radon transform. Conventionally, N-dimensional reconstructions have been carried out with N-1 stages of 2-D backprojection to exploit a dimension-dependent reduction in execution time. The huge data size of 4-D EPR imaging demands the use of a 3-stage reconstruction each consisting of 2-D backprojections. This gives three orders of magnitude reduction in computation relative to a single stage 4-D filtered backprojection. The multi-stage reconstruction, however, requires a uniform angular sampling that yields an inefficient distribution of gradient directions. We introduce a solution that involves acquisition of projections uniformly distributed in solid angle and reconstructs in three 2-D stages with the spatial uniform solid angle data set converted to uniform linear angular projections using 2-D interpolation. Images were taken from the two sampling schemes to compare the spatial resolution and the line width resolution. The degradation in the image quality due to the additional interpolation was small, and we achieved ˜30% reduction in data acquisition time.

  20. JPSS-1 VIIRS Pre-Launch Radiometric Performance

    NASA Technical Reports Server (NTRS)

    Oudrari, Hassan; McIntire, Jeff; Xiong, Xiaoxiong; Butler, James; Efremova, Boryana; Ji, Jack; Lee, Shihyan; Schwarting, Tom

    2015-01-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) on-board the first Joint Polar Satellite System (JPSS) completed its sensor level testing on December 2014. The JPSS-1 (J1) mission is scheduled to launch in December 2016, and will be very similar to the Suomi-National Polar-orbiting Partnership (SNPP) mission. VIIRS instrument was designed to provide measurements of the globe twice daily. It is a wide-swath (3,040 kilometers) cross-track scanning radiometer with spatial resolutions of 370 and 740 meters at nadir for imaging and moderate bands, respectively. It covers the wavelength spectrum from reflective to long-wave infrared through 22 spectral bands [0.412 microns to 12.01 microns]. VIIRS observations are used to generate 22 environmental data products (EDRs). This paper will briefly describe J1 VIIRS characterization and calibration performance and methodologies executed during the pre-launch testing phases by the independent government team, to generate the at-launch baseline radiometric performance, and the metrics needed to populate the sensor data record (SDR) Look-Up-Tables (LUTs). This paper will also provide an assessment of the sensor pre-launch radiometric performance, such as the sensor signal to noise ratios (SNRs), dynamic range, reflective and emissive bands calibration performance, polarization sensitivity, bands spectral performance, response-vs-scan (RVS), near field and stray light responses. A set of performance metrics generated during the pre-launch testing program will be compared to the SNPP VIIRS pre-launch performance.

  1. JPSS-1 VIIRS pre-launch radiometric performance

    NASA Astrophysics Data System (ADS)

    Oudrari, Hassan; McIntire, Jeff; Xiong, Xiaoxiong; Butler, James; Efremova, Boryana; Ji, Qiang; Lee, Shihyan; Schwarting, Tom

    2015-09-01

    The Visible Infrared Imaging Radiometer Suite (VIIRS) on-board the first Joint Polar Satellite System (JPSS) completed its sensor level testing on December 2014. The JPSS-1 (J1) mission is scheduled to launch in December 2016, and will be very similar to the Suomi-National Polar-orbiting Partnership (SNPP) mission. VIIRS instrument was designed to provide measurements of the globe twice daily. It is a wide-swath (3,040 km) cross-track scanning radiometer with spatial resolutions of 370 and 740 m at nadir for imaging and moderate bands, respectively. It covers the wavelength spectrum from reflective to long-wave infrared through 22 spectral bands [0.412 μm to 12.01 μm]. VIIRS observations are used to generate 22 environmental data products (EDRs). This paper will briefly describe J1 VIIRS characterization and calibration performance and methodologies executed during the pre-launch testing phases by the independent government team, to generate the at-launch baseline radiometric performance, and the metrics needed to populate the sensor data record (SDR) Look-Up-Tables (LUTs). This paper will also provide an assessment of the sensor pre-launch radiometric performance, such as the sensor signal to noise ratios (SNRs), dynamic range, reflective and emissive bands calibration performance, polarization sensitivity, bands spectral performance, response-vs-scan (RVS), near field and stray light responses. A set of performance metrics generated during the pre-launch testing program will be compared to the SNPP VIIRS pre-launch performance.

  2. Spectral and spatial shifts of post-ictal slow waves in temporal lobe seizures.

    PubMed

    Yang, Lin; Worrell, Gregory A; Nelson, Cindy; Brinkmann, Benjamin; He, Bin

    2012-10-01

    Temporal lobe seizures have a significant chance to induce impairment of normal brain functions. Even after the termination of ictal discharges, during the post-ictal period, loss of consciousness, decreased responsiveness or other cognitive dysfunctions can persist. Previous studies have found various anatomical and functional abnormalities accompanying temporal lobe seizures, including an abnormal elevation of cortical slow waves. Intracranial electroencephalography studies have shown a prominent increase of lower frequency components during and following seizures that impair (complex partial seizures) but not those that preserve (simple partial seizures) normal consciousness and responsiveness. However, due to the limited spatial coverage of intracranial electroencephalography, the investigation of cortical slow waves cannot be easily extended to the whole brain. In this study, we used scalp electroencephalography to study the spectral features and spatial distribution of post-ictal slow waves with comprehensive spatial coverage. We studied simple partial, complex partial and secondarily generalized seizures in 28 patients with temporal lobe seizures. We used dense-array electroencephalography and source imaging to reconstruct the post-ictal slow-wave distribution. In the studied cohort, we found that a 'global' spectral power shift to lower frequencies accompanied the increased severity of seizures. The delta spectral power relative to higher frequency bands was highest for secondarily generalized seizures, followed by complex partial seizures and lastly simple partial seizures. In addition to this 'global' spectral shift, we found a 'regional' spatial shift in slow-wave activity. Secondarily generalized seizures and complex partial seizures exhibited increased slow waves distributed to frontal areas with spread to contralateral temporal and parietal regions than in simple partial seizures. These results revealed that a widespread cortical network including

  3. Spectral and spatial shifts of post-ictal slow waves in temporal lobe seizures

    PubMed Central

    Yang, Lin; Worrell, Gregory A.; Nelson, Cindy; Brinkmann, Benjamin

    2012-01-01

    Temporal lobe seizures have a significant chance to induce impairment of normal brain functions. Even after the termination of ictal discharges, during the post-ictal period, loss of consciousness, decreased responsiveness or other cognitive dysfunctions can persist. Previous studies have found various anatomical and functional abnormalities accompanying temporal lobe seizures, including an abnormal elevation of cortical slow waves. Intracranial electroencephalography studies have shown a prominent increase of lower frequency components during and following seizures that impair (complex partial seizures) but not those that preserve (simple partial seizures) normal consciousness and responsiveness. However, due to the limited spatial coverage of intracranial electroencephalography, the investigation of cortical slow waves cannot be easily extended to the whole brain. In this study, we used scalp electroencephalography to study the spectral features and spatial distribution of post-ictal slow waves with comprehensive spatial coverage. We studied simple partial, complex partial and secondarily generalized seizures in 28 patients with temporal lobe seizures. We used dense-array electroencephalography and source imaging to reconstruct the post-ictal slow-wave distribution. In the studied cohort, we found that a ‘global’ spectral power shift to lower frequencies accompanied the increased severity of seizures. The delta spectral power relative to higher frequency bands was highest for secondarily generalized seizures, followed by complex partial seizures and lastly simple partial seizures. In addition to this ‘global’ spectral shift, we found a ‘regional’ spatial shift in slow-wave activity. Secondarily generalized seizures and complex partial seizures exhibited increased slow waves distributed to frontal areas with spread to contralateral temporal and parietal regions than in simple partial seizures. These results revealed that a widespread cortical network

  4. Simplified Vicarious Radiometric Calibration

    NASA Technical Reports Server (NTRS)

    Stanley, Thomas; Ryan, Robert; Holekamp, Kara; Pagnutti, Mary

    2010-01-01

    A measurement-based radiance estimation approach for vicarious radiometric calibration of spaceborne multispectral remote sensing systems has been developed. This simplified process eliminates the use of radiative transfer codes and reduces the number of atmospheric assumptions required to perform sensor calibrations. Like prior approaches, the simplified method involves the collection of ground truth data coincident with the overpass of the remote sensing system being calibrated, but this approach differs from the prior techniques in both the nature of the data collected and the manner in which the data are processed. In traditional vicarious radiometric calibration, ground truth data are gathered using ground-viewing spectroradiometers and one or more sun photometer( s), among other instruments, located at a ground target area. The measured data from the ground-based instruments are used in radiative transfer models to estimate the top-of-atmosphere (TOA) target radiances at the time of satellite overpass. These TOA radiances are compared with the satellite sensor readings to radiometrically calibrate the sensor. Traditional vicarious radiometric calibration methods require that an atmospheric model be defined such that the ground-based observations of solar transmission and diffuse-to-global ratios are in close agreement with the radiative transfer code estimation of these parameters. This process is labor-intensive and complex, and can be prone to errors. The errors can be compounded because of approximations in the model and inaccurate assumptions about the radiative coupling between the atmosphere and the terrain. The errors can increase the uncertainty of the TOA radiance estimates used to perform the radiometric calibration. In comparison, the simplified approach does not use atmospheric radiative transfer models and involves fewer assumptions concerning the radiative transfer properties of the atmosphere. This new technique uses two neighboring uniform

  5. An approach to estimate spatial distribution of analyte within cells using spectrally-resolved fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Sharma, Dharmendar Kumar; Irfanullah, Mir; Basu, Santanu Kumar; Madhu, Sheri; De, Suman; Jadhav, Sameer; Ravikanth, Mangalampalli; Chowdhury, Arindam

    2017-03-01

    While fluorescence microscopy has become an essential tool amongst chemists and biologists for the detection of various analyte within cellular environments, non-uniform spatial distribution of sensors within cells often restricts extraction of reliable information on relative abundance of analytes in different subcellular regions. As an alternative to existing sensing methodologies such as ratiometric or FRET imaging, where relative proportion of analyte with respect to the sensor can be obtained within cells, we propose a methodology using spectrally-resolved fluorescence microscopy, via which both the relative abundance of sensor as well as their relative proportion with respect to the analyte can be simultaneously extracted for local subcellular regions. This method is exemplified using a BODIPY sensor, capable of detecting mercury ions within cellular environments, characterized by spectral blue-shift and concurrent enhancement of emission intensity. Spectral emission envelopes collected from sub-microscopic regions allowed us to compare the shift in transition energies as well as integrated emission intensities within various intracellular regions. Construction of a 2D scatter plot using spectral shifts and emission intensities, which depend on the relative amount of analyte with respect to sensor and the approximate local amounts of the probe, respectively, enabled qualitative extraction of relative abundance of analyte in various local regions within a single cell as well as amongst different cells. Although the comparisons remain semi-quantitative, this approach involving analysis of multiple spectral parameters opens up an alternative way to extract spatial distribution of analyte in heterogeneous systems. The proposed method would be especially relevant for fluorescent probes that undergo relatively nominal shift in transition energies compared to their emission bandwidths, which often restricts their usage for quantitative ratiometric imaging in

  6. Spectral and Radiometric Calibration Using Tunable Lasers

    NASA Technical Reports Server (NTRS)

    McCorkel, Joel (Inventor)

    2017-01-01

    A tunable laser system includes a tunable laser, an adjustable laser cavity for producing one or more modes of laser light emitted from the tunable laser, a first optical parametric oscillator positioned in a light path of the adjustable laser cavity, and a controller operable to simultaneously control parameters of at least the tunable laser, the first optical parametric oscillator, and the adjustable laser cavity to produce a range of wavelengths emitted from the tunable laser system. A method of operating a tunable laser system includes using a controller to simultaneously control parameters of a tunable laser, an adjustable laser cavity for producing one or more modes of laser light emitted from the tunable laser, and a first optical parametric oscillator positioned in a light path of the adjustable laser cavity, to produce a range of wavelengths emitted from the tunable laser system.

  7. Spectral and spatial variability of undisturbed and disturbed grass under different view and illumination directions

    NASA Astrophysics Data System (ADS)

    Borel-Donohue, Christoph C.; Shivers, Sarah Wells; Conover, Damon

    2017-05-01

    It is well known that disturbed grass covered surfaces show variability with view and illumination conditions. A good example is a grass field in a soccer stadium that shows stripes indicating in which direction the grass was mowed. These spatial variations are due to a complex interplay of spectral characteristics of grass blades, density, their length and orientations. Viewing a grass surface from nadir or near horizontal directions results in observing different components. Views from a vertical direction show more variations due to reflections from the randomly oriented grass blades and their shadows. Views from near horizontal show a mixture of reflected and transmitted light from grass blades. An experiment was performed on a mowed grass surface which had paths of simulated heavy foot traffic laid down in different directions. High spatial resolution hyperspectral data cubes were taken by an imaging spectrometer covering the visible through near infrared over a period of time covering several hours. Ground truth grass reflectance spectra with a hand held spectrometer were obtained of undisturbed and disturbed areas. Close range images were taken of selected areas with a hand held camera which were then used to reconstruct the 3D geometry of the grass using structure-from-motion algorithms. Computer graphics rendering using raytracing of reconstructed and procedurally created grass surfaces were used to compute BRDF models. In this paper, we discuss differences between observed and simulated spectral and spatial variability. Based on the measurements and/or simulations, we derive simple spectral index methods to detect spatial disturbances and apply scattering models.

  8. The impact of spatial and spectral frequencies in structured light imaging of thick tissues

    NASA Astrophysics Data System (ADS)

    Weber, Jessie Ruth

    This research focuses on development of structured light imaging (SLI), a new optical imaging technique based on spatial frequency domain modulation. The goal of this method is to quantitatively measure and map tissue optical properties, absorption and scattering, to determine tissue biochemical structure and composition. The work presented here extends the technology's spatial and spectral frequency impact. First, to expand the depth sectioning capability of spatial frequency modulation, a layered tissue model was developed, validated and shown to accurately recover in vivo parameters in skin (epidermis and dermis), effectively filtering out signal from the underlying subcutaneous tissue. Next, to expand the impact of spectral frequency information, the SLI system was combined with a Computed Tomography Imaging Spectrometer (CTIS), which eliminates the need to scan through wavelengths when gathering multispectral information. A single SLI-CTIS measurement gathers 36 absorption maps and 36 scattering maps, with a resulting measurement speed ˜30 times faster than the liquid crystal tunable filter method currently employed in multispectral SLI systems. The multispectral information can be used to determine the concentrations of multiple tissue chromophores and the relative density of the tissue. This is immediately useful for monitoring the brain for signs of trauma, including monitoring of oxygen delivery across the brain, mapping of hemoglobin concentration to detect hemorrhage, mapping of water content to monitor edema, and mapping of tissue density to monitor swelling. A simple in vivo brain injury example is presented to demonstrate recovery of these parameters. Finally, to demonstrate the spatial, spectral and temporal resolution of the SLI-CTIS system, measurements were performed on in vivo mouse brain during seizure with electroencephalography (EEG) confirmation.

  9. 3D high spectral and spatial resolution imaging of ex vivo mouse brain

    SciTech Connect

    Foxley, Sean Karczmar, Gregory S.; Domowicz, Miriam; Schwartz, Nancy

    2015-03-15

    Purpose: Widely used MRI methods show brain morphology both in vivo and ex vivo at very high resolution. Many of these methods (e.g., T{sub 2}{sup *}-weighted imaging, phase-sensitive imaging, or susceptibility-weighted imaging) are sensitive to local magnetic susceptibility gradients produced by subtle variations in tissue composition. However, the spectral resolution of commonly used methods is limited to maintain reasonable run-time combined with very high spatial resolution. Here, the authors report on data acquisition at increased spectral resolution, with 3-dimensional high spectral and spatial resolution MRI, in order to analyze subtle variations in water proton resonance frequency and lineshape that reflect local anatomy. The resulting information compliments previous studies based on T{sub 2}{sup *} and resonance frequency. Methods: The proton free induction decay was sampled at high resolution and Fourier transformed to produce a high-resolution water spectrum for each image voxel in a 3D volume. Data were acquired using a multigradient echo pulse sequence (i.e., echo-planar spectroscopic imaging) with a spatial resolution of 50 × 50 × 70 μm{sup 3} and spectral resolution of 3.5 Hz. Data were analyzed in the spectral domain, and images were produced from the various Fourier components of the water resonance. This allowed precise measurement of local variations in water resonance frequency and lineshape, at the expense of significantly increased run time (16–24 h). Results: High contrast T{sub 2}{sup *}-weighted images were produced from the peak of the water resonance (peak height image), revealing a high degree of anatomical detail, specifically in the hippocampus and cerebellum. In images produced from Fourier components of the water resonance at −7.0 Hz from the peak, the contrast between deep white matter tracts and the surrounding tissue is the reverse of the contrast in water peak height images. This indicates the presence of a shoulder in

  10. Tensor subspace analysis for spatial-spectral classification of hyperspectral data

    NASA Astrophysics Data System (ADS)

    Fan, Lei; Messinger, David W.

    2016-05-01

    Remotely sensed data fusion aims to integrate multi-source information generated from different perspectives, acquired with different sensors or captured at different times in order to produce fused data that contains more information than one individual data source. Recently, extended morphological attribute profiles (EMAPs) were proposed to embed contextual information, such as texture, shape, size and etc., into a high dimensional feature space as an alternative data source to hyperspectral image (HSI). Although EMAPs provide greater capabilities in modeling both spatial and spectral information, they lead to an increase in the dimensionality of the extracted features. Conventionally, a data point in high dimensional feature space is represented by a vector. For HSI, this data representation has one obvious shortcoming in that only spectral knowledge is utilized without contextual relationship being exploited. Tensors provide a natural representation for HSI data by incorporating both spatial neighborhood awareness and spectral information. Besides, tensors can be conveniently incorporated into a superpixel-based HSI image processing framework. In our paper, three tensor-based dimensionality reduction (DR) approaches were generalized for high dimensional image with promising results reported. Among the tensor-based DR approaches, the Tensor Locality Preserving Projection (TLPP) algorithm utilized graph Laplacian to model the pairwise relationship among the tensor data points. It also demonstrated excellent performance for both pixel-wise and superpixel-wise classification on Pavia University dataset.

  11. Radiometric sounding system

    SciTech Connect

    Whiteman, C.D.; Anderson, G.A.; Alzheimer, J.M.; Shaw, W.J.

    1995-04-01

    Vertical profiles of solar and terrestrial radiative fluxes are key research needs for global climate change research. These fluxes are expected to change as radiatively active trace gases are emitted to the earth`s atmosphere as a consequence of energy production and industrial and other human activities. Models suggest that changes in the concentration of such gases will lead to radiative flux divergences that will produce global warming of the earth`s atmosphere. Direct measurements of the vertical variation of solar and terrestrial radiative fluxes that lead to these flux divergences have been largely unavailable because of the expense of making such measurements from airplanes. These measurements are needed to improve existing atmospheric radiative transfer models, especially under the cloudy conditions where the models have not been adequately tested. A tethered-balloon-borne Radiometric Sounding System has been developed at Pacific Northwest Laboratory to provide an inexpensive means of making routine vertical soundings of radiative fluxes in the earth`s atmospheric boundary layer to altitudes up to 1500 m above ground level. Such vertical soundings would supplement measurements being made from aircraft and towers. The key technical challenge in the design of the Radiometric Sounding System is to develop a means of keeping the radiometers horizontal while the balloon ascends and descends in a turbulent atmospheric environment. This problem has been addressed by stabilizing a triangular radiometer-carrying platform that is carried on the tetherline of a balloon sounding system. The platform, carried 30 m or more below the balloon to reduce the balloon`s effect on the radiometric measurements, is leveled by two automatic control loops that activate motors, gears and pulleys when the platform is off-level. The sensitivity of the automatic control loops to oscillatory motions of various frequencies and amplitudes can be adjusted using filters.

  12. Relative Radiometric Normalization and Atmospheric Correction of a SPOT 5 Time Series

    PubMed Central

    Hajj, Mahmoud El; Bégué, Agnès; Lafrance, Bruno; Hagolle, Olivier; Dedieu, Gérard; Rumeau, Matthieu

    2008-01-01

    Multi-temporal images acquired at high spatial and temporal resolution are an important tool for detecting change and analyzing trends, especially in agricultural applications. However, to insure a reliable use of this kind of data, a rigorous radiometric normalization step is required. Normalization can be addressed by performing an atmospheric correction of each image in the time series. The main problem is the difficulty of obtaining an atmospheric characterization at a given acquisition date. In this paper, we investigate whether relative radiometric normalization can substitute for atmospheric correction. We develop an automatic method for relative radiometric normalization based on calculating linear regressions between unnormalized and reference images. Regressions are obtained using the reflectances of automatically selected invariant targets. We compare this method with an atmospheric correction method that uses the 6S model. The performances of both methods are compared using 18 images from of a SPOT 5 time series acquired over Reunion Island. Results obtained for a set of manually selected invariant targets show excellent agreement between the two methods in all spectral bands: values of the coefficient of determination (r2 exceed 0.960, and bias magnitude values are less than 2.65. There is also a strong correlation between normalized NDVI values of sugarcane fields (r2 = 0.959). Despite a relative error of 12.66% between values, very comparable NDVI patterns are observed. PMID:27879849

  13. Radiometric resolution enhancement by lossy compression as compared to truncation followed by lossless compression

    NASA Technical Reports Server (NTRS)

    Tilton, James C.; Manohar, Mareboyana

    1994-01-01

    Recent advances in imaging technology make it possible to obtain imagery data of the Earth at high spatial, spectral and radiometric resolutions from Earth orbiting satellites. The rate at which the data is collected from these satellites can far exceed the channel capacity of the data downlink. Reducing the data rate to within the channel capacity can often require painful trade-offs in which certain scientific returns are sacrificed for the sake of others. In this paper we model the radiometric version of this form of lossy compression by dropping a specified number of least significant bits from each data pixel and compressing the remaining bits using an appropriate lossless compression technique. We call this approach 'truncation followed by lossless compression' or TLLC. We compare the TLLC approach with applying a lossy compression technique to the data for reducing the data rate to the channel capacity, and demonstrate that each of three different lossy compression techniques (JPEG/DCT, VQ and Model-Based VQ) give a better effective radiometric resolution than TLLC for a given channel rate.

  14. Mapping plastic greenhouse with medium spatial resolution satellite data: Development of a new spectral index

    NASA Astrophysics Data System (ADS)

    Yang, Dedi; Chen, Jin; Zhou, Yuan; Chen, Xiang; Chen, Xuehong; Cao, Xin

    2017-06-01

    Plastic greenhouses (PGs) are an important agriculture development technique to protect and control the growing environment for food crops. The extensive use of PGs can change the agriculture landscape and affects the local environment. Accurately mapping and estimating the coverage of PGs is a necessity to the strategic planning of modern agriculture. Unfortunately, PG mapping over large areas is methodologically challenging, as the medium spatial resolution satellite imagery (such as Landsat data) used for analysis lacks spatial details and spectral variations. To fill the gap, the paper proposes a new plastic greenhouse index (PGI) based on the spectral, sensitivity, and separability analysis of PGs using medium spatial resolution images. In the context of the Landsat Enhanced Thematic Mapper Plus (ETM+) imagery, the paper examines the effectiveness and capability of the proposed PGI. The results indicate that PGs in Landsat ETM+ image can be successfully detected by the PGI if the PG fraction is greater than 12% in a mixed pixel. A kappa coefficient of 0.83 and overall accuracy of 91.2% were achieved when applying the proposed PGI in the case of Weifang District, Shandong, China. These results show that the proposed index can be applied to identifying transparent PGs in atmospheric corrected Landsat image and has the potential for the digital mapping of plastic greenhouse coverage over a large area.

  15. Persistence of atomic spectral line on laser-induced Cu plasma with spatial confinement

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Chen, Anmin; Sui, Laizhi; Li, Suyu; Liu, Dunli; Wang, Xiaowei; Jiang, Yuanfei; Huang, Xuri; Jin, Mingxing

    2016-11-01

    This paper carries out the spatial confinement effect on laser-induced Cu breakdown spectroscopy in a cylindrical cavity via a nanosecond pulsed Q-switch Nd:YAG laser operating at a wavelength of 1064 nm. The temporal evolution of the laser-induced plasma spectroscopy is used to investigate the characteristics of spectral persistence. The atomic spectral persistence in plasma generated from Cu with spatial confinement is experimentally demonstrated, where the results indicate that the diameter of the confinement cavity plays a very important role in the persistence of an excited neutral Cu emission line, while the depth of the confinement cavity is almost independent of Cu (I) line persistence. As the diameter of the confinement cavity increases, the persistence of the Cu (I) line in the plasma grows longer under a certain limit. The likely reason for this phenomenon is that under spatial confinement, the reflected shockwave compresses the plasma and leads to an increase in the plasma temperature and density at a certain delay time, which causes further excitation of atomic population to higher excited levels. Finally, the collision rate between particles in the plasma plume is increased.

  16. SPATIAL AND SPECTRAL MODELING OF THE GAMMA-RAY DISTRIBUTION IN THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Foreman, Gary; Chu, You-Hua; Gruendl, Robert; Fields, Brian; Ricker, Paul; Hughes, Annie

    2015-07-20

    We perform spatial and spectral analyses of the LMC gamma-ray emission collected over 66 months by the Fermi Gamma-ray Space Telescope. In our spatial analysis, we model the LMC cosmic-ray distribution and gamma-ray production using observed maps of the LMC interstellar medium, star formation history, interstellar radiation field, and synchrotron emission. We use bootstrapping of the data to quantify the robustness of spatial model performance. We model the LMC gamma-ray spectrum using fitting functions derived from the physics of π{sup 0} decay, Bremsstrahlung, and inverse Compton scattering. We find the integrated gamma-ray flux of the LMC from 200 MeV to 20 GeV to be 1.37 ± 0.02 × 10{sup −7} ph cm{sup −2} s{sup −1}, of which we attribute about 6% to inverse Compton scattering and 44% to Bremsstrahlung. From our work, we conclude that the spectral index of the LMC cosmic-ray proton population is 2.4 ± 0.2, and we find that cosmic-ray energy loss through gamma-ray production is concentrated within a few 100 pc of acceleration sites. Assuming cosmic-ray energy equipartition with magnetic fields, we estimate LMC cosmic rays encounter an average magnetic field strength ∼3 μG.

  17. Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use.

    PubMed

    Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale; Manceron, Laurent

    2016-06-01

    When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6-20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here.

  18. Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use

    SciTech Connect

    Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale; Manceron, Laurent

    2016-06-15

    When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6–20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here.

  19. Spectral and Spatial Distribution of the Scattered Radiation of AN Electron Radiotherapy Beam

    NASA Astrophysics Data System (ADS)

    Bartesaghi, G.; Conti, V.; Mascagna, V.; Prest, M.; Mozzanica, A.; Frigerio, G.; Monti, A.; Vallazza, E.

    2006-04-01

    The characterization of the radiation scattered by the collimating system of a linear accelerator for medical applications is becoming a must given the increase in the survival of the radio-treated patients. This paper describes both the spectral and spatial study of the scattered radiation of an electron beam in the energy range 6-20 MeV, produced by a Varian CLINAC 1800 accelerator at the Radiotherapy Unit of the Sant'Anna Hospital in Como. The detectors used are plastic and fiber scintillators characterized by a timing response of ≈ 25 nsec in order to cope with the high fluxes. The results have been compared with a Montecarlo simulation based on Geant 3.21 and are presented both in terms of spectral and dose distributions.

  20. Application requirement analysis of high spectral and high spatial resolution satellite for environment remote sensing monitoring

    NASA Astrophysics Data System (ADS)

    Liu, S. H.; Yang, Y. P.; Zhao, Z. H.; Yao, Y. J.; Mao, X. J.; Wu, Y. T.; Gao, Y. H.

    2016-03-01

    China's environmental situation is still grim, environmental pressure continues to increase. The demand of environmental protection work in the new era for high resolution remote sensing application will continue to increase. Environmental monitoring has multi factor, quantitative inversion and high precision as features, environment department need to use a wide spectrum of remote sensing data with high spectral resolution capability to monitor the total amount of pollutants in macro scale and long time series. The implementation of the high resolution earth observation project provides support for the improvement of the quantitative application of environmental remote sensing. On the basis of sorting out the key work of environmental protection, the application requirements of high spectral resolution and high spatial resolution satellite remote sensing in the field of environmental protection and the building needs of national environmental remote sensing application platform are put forward.

  1. Simultaneous spatial and spectral mapping of flow using photoacoustic Doppler measurement

    NASA Astrophysics Data System (ADS)

    Sheinfeld, Adi; Gilead, Sharon; Eyal, Avishay

    2010-11-01

    We demonstrate the use of tone-burst excitation and time-gated spectral analysis for photoacoustic Doppler mapping of flow in an unperturbed vessel phantom and in a vessel with a spatially varying lumen. The method, which mimics pulsed Doppler ultrasound, enables simultaneous measurement of axial position and flow as well as complete characterization of the Doppler spectrum over a wide range of mean velocities (3.5 to 200 mm/s). To generate the required optical excitation, a continuous cw laser source followed by an external electro-optic modulator is used. Stenoses at various levels are emulated in a C-flex tube with a flowing suspension of micrometer-scale carbon particles. Two-dimensional maps of spectral content versus axial position at different points along the vessel and for various levels of perturbations demonstrate the potential use of the method for characterization of flow irregularities.

  2. Improved mid infrared detector for high spectral or spatial resolution and synchrotron radiation use

    NASA Astrophysics Data System (ADS)

    Faye, Mbaye; Bordessoule, Michel; Kanouté, Brahim; Brubach, Jean-Blaise; Roy, Pascale; Manceron, Laurent

    2016-06-01

    When using bright, small effective size sources, such as synchrotron radiation light beam, for broadband spectroscopy at spectral or spatial high resolution for mid-IR FTIR measurements, a marked detectivity improvement can be achieved by setting up a device matching the detector optical étendue to that of the source. Further improvement can be achieved by reducing the background unmodulated flux and other intrinsic noise sources using a lower temperature cryogen, such as liquid helium. By the combined use of cooled apertures, cold reimaging optics, filters and adapted detector polarization, and preamplification electronics, the sensitivity of a HgCdTe photoconductive IR detector can be improved by a significant factor with respect to standard commercial devices (more than one order of magnitude on average over 6-20 μm region) and the usable spectral range extended to longer wavelengths. The performances of such an optimized detector developed on the AILES Beamline at SOLEIL are presented here.

  3. Assessing spatial and seasonal variations in grasslands with spectral reflectances from a helicopter platform

    NASA Technical Reports Server (NTRS)

    Walthall, Charles L.; Middleton, Elizabeth M.

    1992-01-01

    The helicopter system data acquisition technique has shown to be a viable means of gathering surface data with spectral detail adequate for intersite, intrasite, and temporal characterizations and for assessing temporal and spatial variability throughout the FIFE 1987 IFCs. The successful employment of nadir measurements for grassland assessments is notable given the reflectance anisotropy (Middleton, 1992). Though only five sites were repetitively observed, the conclusions reached from this particular sample of sites agree well with assessments from other data sources (Sellars et al., 1990 and Kittel et al., 1990).

  4. Advanced Remote-Sensing Imaging Emission Spectrometer (ARIES): AIRS Spectral Resolution with MODIS Spatial Resolution

    NASA Technical Reports Server (NTRS)

    Pagano, Thomas S.; Chahine, Moustafa T.; Aumann, Hartmut H.; OCallaghan, Fred

    2006-01-01

    The Advanced Remote-sensing Imaging Emission Spectrometer (ARIES) will measure a wide range of earth quantities fundamental to the study of global climate change. It will build upon the success of the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) instruments currently flying on the EOS Aqua Spacecraft. Both instruments are facility instruments for NASA providing data to thousands of scientists investigating land, ocean and atmospheric Earth System processes. ARIES will meet all the requirements of AIRS and MODIS in a single compact instrument, while providing the next-generation capability of improved spatial resolution for AIRS and improved spectral resolution for MODIS.

  5. Spectral and spatial characteristics of third-harmonic generation in conical light beams

    SciTech Connect

    Peet, V.E.; Shchemeljov, S.V.

    2003-01-01

    Generation of resonance-enhanced third harmonic in Bessel and other conical beams is analyzed from a simple picture, where the fundamental light field is decomposed into elementary configurations of crossed plain-wave sub-beams. We show that the overall harmonic output can be derived as a superposition of all partial harmonic components driven by elementary configurations of the fundamental field. Good agreement with experimental observations has been obtained in simulation of spectral and spatial characteristics of the generated third harmonic. Some peculiarities of harmonic generation in conical light fields are discussed.

  6. Color camera computed tomography imaging spectrometer for improved spatial-spectral image accuracy

    NASA Technical Reports Server (NTRS)

    Wilson, Daniel W. (Inventor); Bearman, Gregory H. (Inventor); Johnson, William R. (Inventor)

    2011-01-01

    Computed tomography imaging spectrometers ("CTIS"s) having color focal plane array detectors are provided. The color FPA detector may comprise a digital color camera including a digital image sensor, such as a Foveon X3.RTM. digital image sensor or a Bayer color filter mosaic. In another embodiment, the CTIS includes a pattern imposed either directly on the object scene being imaged or at the field stop aperture. The use of a color FPA detector and the pattern improves the accuracy of the captured spatial and spectral information.

  7. [Common and individual in EEG spectral differences while performing verbal and spatial tasks].

    PubMed

    Dan'ko, N Iu; Ivanitskiĭ, G A; Boĭtsova, Iu A; Solov'eva, M L; Roik, A O

    2013-01-01

    It is shown previously that types of carried-out spatial-figurative and verbal-logic tasks can be distinguished by means of the trained automatic classifier, using individual for each examinee characteristics of EEG power spectra. Research with application of a subset of the same tasks, but aimed to identify the EEG spectral power group differences has been carried out with 31 participants. Contrast distribution of statistically significant differences on frequency bands qualitatively coincides with ranging of the bands by estimates of efficiency of recognition with the trained classifier, except for a range theta. Alpha bands are most involved. Results of comparison of the general (group) and individual indicators correspond to ideas of more significant involvement of mechanisms of semantic memory in the solution of verbal tasks, and also point to possible differences in balance of internal and external attention at realization of verbal-logic and spatial-figurative activity.

  8. Spatial hole burning and spectral stability of a quantum-dot laser

    SciTech Connect

    Savelyev, A. V. Korenev, V. V.; Maximov, M. V.; Zhukov, A. E.

    2015-11-15

    The inhomogeneous intensity distribution of the optical model along the axis of a semiconductor quantum-dot laser results in spatial hole burning. The influence of this phenomenon on the stability of the multifrequency emission spectrum is studied when the optical transition of the quantum dots is characterized by considerable homogeneous broadening. The results of two models—in which inhomogeneous broadening is disregarded and taken into account—regarding the stability of the radiation spectrum under the influence of slight variation of the spectral loss dependence in the resonator are compared. Inhomogeneous distribution of the charge carriers (spatial hole burning) is found to be a critical factor in determining the form and stability of the spectrum.

  9. Novel characterization of the nonlinear refractive response of materials using spatially and spectrally resolved interferometry

    NASA Astrophysics Data System (ADS)

    Meier, Amanda; Adams, Daniel; Squier, Jeff; Durfee, Charles

    2010-10-01

    Characterization of the nonlinear refractive index of a material is important in order to fully understand the nonlinear propagation of femtosecond laser pulses. The most common method to obtaining the nonlinear refractive index is Z-scan. However, since it averages over pulse duration and beam profile, Z-scan is not reliable when there is time- and intensity-dependence of the nonlinear response. The new method we are exploring to make these nonlinear refractive index measurements is spatially and spectrally resolved interferometry (SSRI). SSRI is a method that can give a simultaneous measurement of the spatial wave-front across the frequency or temporal profile of the pulse. The SSRI method proves better in measuring response at specific y and t, allowing it to measure both delayed response and saturation effects. The ability to make a measurement in both dimensions enables understanding of spatiotemporal dynamics in other experiments as cross-wave polarization and filamentation.

  10. Improved Cloud and Snow Screening in MAIAC Aerosol Retrievals Using Spectral and Spatial Analysis

    NASA Technical Reports Server (NTRS)

    Lyapustin, A.; Wang, Y.; Laszlo, I.; Kokrkin, S.

    2012-01-01

    An improved cloud/snow screening technique in the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm is described. It is implemented as part of MAIAC aerosol retrievals based on analysis of spectral residuals and spatial variability. Comparisons with AERONET aerosol observations and a large-scale MODIS data analysis show strong suppression of aerosol optical thickness outliers due to unresolved clouds and snow. At the same time, the developed filter does not reduce the aerosol retrieval capability at high 1 km resolution in strongly inhomogeneous environments, such as near centers of the active fires. Despite significant improvement, the optical depth outliers in high spatial resolution data are and will remain the problem to be addressed by the application-dependent specialized filtering techniques.

  11. JPSS-1 VIIRS Pre-Launch Radiometric Performance

    NASA Technical Reports Server (NTRS)

    Oudrari, Hassan; Mcintire, Jeffrey; Xiong, Xiaoxiong; Butler, James; Ji, Qiang; Schwarting, Tom; Zeng, Jinan

    2015-01-01

    The first Joint Polar Satellite System (JPSS-1 or J1) mission is scheduled to launch in January 2017, and will be very similar to the Suomi-National Polar-orbiting Partnership (SNPP) mission. The Visible Infrared Imaging Radiometer Suite (VIIRS) on board the J1 spacecraft completed its sensor level performance testing in December 2014. VIIRS instrument is expected to provide valuable information about the Earth environment and properties on a daily basis, using a wide-swath (3,040 km) cross-track scanning radiometer. The design covers the wavelength spectrum from reflective to long-wave infrared through 22 spectral bands, from 0.412 m to 12.01 m, and has spatial resolutions of 370 m and 740 m at nadir for imaging and moderate bands, respectively. This paper will provide an overview of pre-launch J1 VIIRS performance testing and methodologies, describing the at-launch baseline radiometric performance as well as the metrics needed to calibrate the instrument once on orbit. Key sensor performance metrics include the sensor signal to noise ratios (SNRs), dynamic range, reflective and emissive bands calibration performance, polarization sensitivity, bands spectral performance, response-vs-scan (RVS), near field response, and stray light rejection. A set of performance metrics generated during the pre-launch testing program will be compared to the sensor requirements and to SNPP VIIRS pre-launch performance.

  12. Effects of decreasing resolution on spectral and spatial information content in an agricultural area. [Pottawatmie study site, Iowa and Nebraska

    NASA Technical Reports Server (NTRS)

    1983-01-01

    The effects of decreasing spatial resolution from 6 1/4 miles square to 50 miles square are described. The effects of increases in cell size is studied on; the mean and variance of spectral data; spatial trends; and vegetative index numbers. Information content changes on cadastral, vegetal, soil, water and physiographic information are summarized.

  13. A unified description of spatial and spectral distribution of fluctuation intensities in wall turbulence

    NASA Astrophysics Data System (ADS)

    Ji, Yong; She, Zhen-Su

    2016-11-01

    The streamwise turbulent intensity in wall turbulence (pipe and boundary layer) presents non-uniform distribution in both physical and wave number space. The well-known Townsend-Perry attached eddy hypothesis divides the energy spectrum into three distinct ranges: a constant range at small wavenumbers kspectral model is needed. We present here a unified analytical expression, based on a generalized dilation-invariant ansatz. It will be shown that analytic description of a stress length ell giving rise to accurate description of the mean velocity profile yields equally accurate prediction of the integral scale wavenumber ki, and the predicted dissipation gives rise of good prediction of the Kolmorogov dissipation wavenumber kd. Finally, the large-scale characteristic wavenumber kc follows a simple scaling law in terms of the stress length ell. Furthermore, we find that the Princeton data reveals possible anomalous scaling in the k-1 and k-5/3 range. The spectral curves based on our generalized dilation-invariant ansatz agree very well with the experimental spectrum, and the kinetic energy profile is also accurately reproduced. We have thus achieved, for the first time, a unified description of spatial and spectral distribution of fluctuation intensity from a recently developed symmetry approach.

  14. Retrieving LAI from Remotely Sensed Images: Spectral Indices vs. Spatial Texture

    NASA Astrophysics Data System (ADS)

    Song, C.; Gray, J. M.; Zhang, S.

    2008-12-01

    Leaves are the interface where energy and gas exchanges between the atmosphere and forest ecosystems occur. Accurate knowledge of the amount leaves is essential to successfully modeling the fluxes of water and carbon through the earth's forests. Leaf area index (LAI) is a parameter used to quantify the abundance of leaves in a given stand. Remote sensing offers the only feasible way to quantify LAI over large areas. Tremendous efforts have been devoted to this task by remote sensing scientists, but there is still a lack of concensus on how LAI can be best retrieved. Though global LAI products are available, their accuracy has remained unsatisfactory for regional applications. Previous work has primarily focused on using the spectral information in remotely sensed imagery. In this study, we compared the potential of LAI retrieval from various spectral indices derived from Landsat TM images with retrieval using the spatial information, image texture, derived from the Ikonos images. LAI on the ground was derived from allometry, LAI-2000 and the TRAC device in the Duke Forest area in central North Carolina. Our results show that the commonly used spectral indices, normalized difference vegetation index (NDVI) and simple ratio vegetation index (SRVI) were not the best choice for LAI retrieval. We found that Landsat TM derived Structural Index (SI=TM4/TM5) and normalized difference water index (NDWI), as well as Ikonos image texture are much better alternatives.

  15. Wide-Field Imaging Interferometry Spatial-Spectral Image Synthesis Algorithms

    NASA Technical Reports Server (NTRS)

    Lyon, Richard G.; Leisawitz, David T.; Rinehart, Stephen A.; Memarsadeghi, Nargess; Sinukoff, Evan J.

    2012-01-01

    Developed is an algorithmic approach for wide field of view interferometric spatial-spectral image synthesis. The data collected from the interferometer consists of a set of double-Fourier image data cubes, one cube per baseline. These cubes are each three-dimensional consisting of arrays of two-dimensional detector counts versus delay line position. For each baseline a moving delay line allows collection of a large set of interferograms over the 2D wide field detector grid; one sampled interferogram per detector pixel per baseline. This aggregate set of interferograms, is algorithmically processed to construct a single spatial-spectral cube with angular resolution approaching the ratio of the wavelength to longest baseline. The wide field imaging is accomplished by insuring that the range of motion of the delay line encompasses the zero optical path difference fringe for each detector pixel in the desired field-of-view. Each baseline cube is incoherent relative to all other baseline cubes and thus has only phase information relative to itself. This lost phase information is recovered by having point, or otherwise known, sources within the field-of-view. The reference source phase is known and utilized as a constraint to recover the coherent phase relation between the baseline cubes and is key to the image synthesis. Described will be the mathematical formalism, with phase referencing and results will be shown using data collected from NASA/GSFC Wide-Field Imaging Interferometry Testbed (WIIT).

  16. Global analysis of microscopic fluorescence lifetime images using spectral segmentation and a digital micromirror spatial illuminator.

    PubMed

    Bednarkiewicz, Artur; Whelan, Maurice P

    2008-01-01

    Fluorescence lifetime imaging (FLIM) is very demanding from a technical and computational perspective, and the output is usually a compromise between acquisition/processing time and data accuracy and precision. We present a new approach to acquisition, analysis, and reconstruction of microscopic FLIM images by employing a digital micromirror device (DMD) as a spatial illuminator. In the first step, the whole field fluorescence image is collected by a color charge-coupled device (CCD) camera. Further qualitative spectral analysis and sample segmentation are performed to spatially distinguish between spectrally different regions on the sample. Next, the fluorescence of the sample is excited segment by segment, and fluorescence lifetimes are acquired with a photon counting technique. FLIM image reconstruction is performed by either raster scanning the sample or by directly accessing specific regions of interest. The unique features of the DMD illuminator allow the rapid on-line measurement of global good initial parameters (GIP), which are supplied to the first iteration of the fitting algorithm. As a consequence, a decrease of the computation time required to obtain a satisfactory quality-of-fit is achieved without compromising the accuracy and precision of the lifetime measurements.

  17. Spectral-spatial classification of hyperspectral images using trilateral filter and stacked sparse autoencoder

    NASA Astrophysics Data System (ADS)

    Zhao, Chunhui; Wan, Xiaoqing; Zhao, Genping; Yan, Yiming

    2017-01-01

    A spectral-spatial classification method using a trilateral filter (TF) and stacked sparse autoencoder (SSA) for improving the classification accuracy of hyperspectral image (HSI) is proposed. The operation is carried out in two main stages: edge-preserved smoothing and high-level feature learning. First, a reference image obtained from dual tree complex wavelet transform is adopted in a TF for smoothing the HSI. As expected, the filter not only can effectively attenuate the mixed noise (e.g., Gaussian noise and impulse noise) where the bilateral filter shows poor performance but also can produce useful spectral-spatial features from HSI by considering geometric closeness and photometric similarity between pixels simultaneously. Second, an artificial fish swarm algorithm (AFSA) is first introduced into a SSA, and the proposed deep learning architecture is used to adaptively exploit more abstract and differentiable high-level feature representations from the smoothed HSI, based on the factor that AFSA provides better trade-off among concurrency, search efficiency, and convergence rate compared with gradient descent and back-propagation algorithms in a traditional SSA. Finally, a random forest classifier is utilized to perform supervised fine-tuning and classification. Experimental results on two real HSI data sets demonstrate that the proposed method generates competitive performance compared with those of conventional methods.

  18. Mapping invasive Fallopia japonica by combined spectral, spatial, and temporal analysis of digital orthophotos

    NASA Astrophysics Data System (ADS)

    Dorigo, Wouter; Lucieer, Arko; Podobnikar, Tomaž; Čarni, Andraž

    2012-10-01

    Japanese knotweed (Fallopia japonica) is listed among 100 of the World's worst invasive alien species and poses an increasing threat to ecosystems and agriculture in Northern America, Europe, and Oceania. This study proposes a remote sensing method to detect local occurrences of F. japonica from low-cost digital orthophotos taken in early spring and summer by concurrently exploring its temporal, spectral, and spatial characteristics. Temporal characteristics of the species are quantified by a band ratio calculated from the green and red spectral channels of both images. The normalized difference vegetation index was used to capture the high near-infrared (NIR) reflectance of F. japonica in summer while the characteristic texture of F. japonica is quantified by calculating gray level co-occurrence matrix (GLCM) measures. After establishing the optimum kernel size to quantify texture, the different input features (spectral, spatial, and texture) were stacked and used as input to the random forest (RF) classifier. The proposed method was tested for a built-up and semi-natural area in Slovenia. The spectral, spatial, and temporal provided an equally important contribution for differentiating F. japonica from other land cover types. The combination of all signatures resulted in a producer accuracy of 90.3% and a user accuracy of 98.1% for F. japonica when validation was based on independent regions of interest. A producer accuracy of 61.4% was obtained for F. japonica when comparing the classification result with all occurrences of F. japonica identified during a field validation campaign. This is an encouraging result given the very small patches in which the species usually occur and the high degree of intermingling with other plants. All hot spots were identified and even likely infestations of F. japonica that had remained undiscovered during the field campaign were detected. The probability images resulting from the RF classifier can be used to reduce the

  19. Spectral and Spatial Analysis of Volatile Deposits in Io's Loki Patera

    NASA Astrophysics Data System (ADS)

    Landis, C. E.; Howell, R. R.

    2012-12-01

    Loki Patera is an active volcanic feature approximately 200 km in diameter on Jupiter's moon Io. The goals of this research are to better understand the nature of volatile distribution in and around the Loki region. Images taken by Voyager I show a number of bright features distributed across the patera surface. These features, referred to as "bergs," may be fumaroles which allow sulfur gases from the lava beneath the hardened crust to escape onto the surface. By examining the spatial distribution of the bergs and the spectral signatures of bergs and other features around Loki Patera, we can better understand their role in the volcanic activity observed at Loki, and perhaps elsewhere on Io. Spectral data from the Voyager and Galileo missions were examined using ISIS3, a program suite developed by the USGS. Photometric corrections were applied to the images to adjust for changes in lighting geometry. The spatial distribution of the bergs was examined using ArcMap. Initial results indicate that the bergs seldom occur near the inner and outer edges of the patera, which are known to be hotter than other parts of the patera. The lack of bergs in this area suggests that thermal properties of the crust may control the distribution of the bergs. The spacing of the bergs, which on average are about 6 km from each other, and other distribution statistics are used to test whether there is some maximum area of crust in which one berg can accommodate the escaping gases. The spectral signatures of the bergs themselves are compared to other surface features in and around the patera. Further study of the bergs and other features will continue to shed light on the underlying geologic and volcanic processes responsible for the activity at Loki. This work was supported in part by NASA JDAP grant NNX09AE06G.

  20. High Spectral and Spatial Resolution Observations of Mars in 1999 and 2001

    NASA Astrophysics Data System (ADS)

    Simrell, E. R.; Chanover, N. J.; Murphy, J.; Beebe, R. F.; Hillman, J. J.; Glenar, D. A.; Kervin, P.; Africano, J. L.; Roberts, L., Jr.

    2001-12-01

    Visible and near-IR imaging observations of Mars were made during the 1999 and 2001 apparitions using high spectral and spatial resolution techniques that employ acousto-optic tuning and adaptive optics. The 1999 images were taken at the Apache Point Observatory 3.5 meter telescope using a near-infrared acousto-optic tunable filter (AOTF) camera, which operated between 1.6 and 3.6 microns. This enabled us to acquire ``spectral image cubes'' (x,y images with wavelength as the z-dimension) across the H and K bands on 24-25 April 1999. We analyzed the disk-integrated brightness across the H and K bands in an effort to identify atmospheric and/or surface absorption bands of CO2 and H2O. The AOTF data are examined to determine the optimal spectral resolution for spatially resolved images of Mars. The 2001 data were acquired between 18 March and 08 July 2001 in a service observing mode at the Air Force Advanced Electro-Optical System (AEOS) 3.6 meter telescope. This telescope is equipped with an adaptive optics (AO) system, and we utilized the facility AO science camera with several broad-band filters in the red/near-IR. These data are used for the characterization of several narrow-band filters that will be purchased for the AO system. Surface features in this data set are compared to those seen in recent Hubble Space Telescope imagery of Mars in a comparison of ground-based adaptive optics vs. spacecraft imaging techniques. Observations made at the Maui Space Surveillance System (MSSS), Maui, Hawaii, USA, were made as part of a collaboration between New Mexico State University and Detachment 15 of the US Air Force Research Laboratory's Directed Energy Directorate, which owns and operates the MSSS.

  1. SNPP VIIRS spectral bands co-registration and spatial response characterization

    NASA Astrophysics Data System (ADS)

    Lin, Guoqing; Tilton, James C.; Wolfe, Robert E.; Tewari, Krishna P.; Nishihama, Masahiro

    2013-09-01

    The Visible Infrared Imager Radiometer Suite (VIIRS) instrument onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite was launched on 28 October 2011. The VIIRS has 5 imagery spectral bands (I-bands), 16 moderate resolution spectral bands (M-bands) and a panchromatic day/night band (DNB). Performance of the VIIRS spatial response and band-to-band co-registration (BBR) was measured through intensive pre-launch tests. These measurements were made in the non-aggregated zones near the start (or end) of scan for the I-bands and M-bands and for a limited number of aggregation modes for the DNB in order to test requirement compliance. This paper presents results based on a recently re-processed pre-launch test data. Sensor (detector) spatial impulse responses in the scan direction are parameterized in terms of ground dynamic field of view (GDFOV), horizontal spatial resolution (HSR), modulation transfer function (MTF), ensquared energy (EE) and integrated out-of-pixel (IOOP) spatial response. Results are presented for the non-aggregation, 2-sample and 3-sample aggregation zones for the I-bands and M-bands, and for a limited number of aggregation modes for the DNB. On-orbit GDFOVs measured for the 5 I-bands in the scan direction using a straight bridge are also presented. Band-to-band co-registration (BBR) is quantified using the prelaunch measured band-to-band offsets. These offsets may be expressed as fractions of horizontal sampling intervals (HSIs), detector spatial response parameters GDFOV or HSR. BBR bases on HSIs in the non-aggregation, 2-sample and 3-sample aggregation zones are presented. BBR matrices based on scan direction GDFOV and HSR are compared to the BBR matrix based on HSI in the non-aggregation zone. We demonstrate that BBR based on GDFOV is a better representation of footprint overlap and so this definition should be used in BBR requirement specifications. We propose that HSR not be used as the primary image quality indicator, since we

  2. SNPP VIIRS Spectral Bands Co-Registration and Spatial Response Characterization

    NASA Technical Reports Server (NTRS)

    Lin, Guoqing; Tilton, James C.; Wolfe, Robert E.; Tewari, Krishna P.; Nishihama, Masahiro

    2013-01-01

    The Visible Infrared Imager Radiometer Suite (VIIRS) instrument onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite was launched on 28 October 2011. The VIIRS has 5 imagery spectral bands (I-bands), 16 moderate resolution spectral bands (M-bands) and a panchromatic day/night band (DNB). Performance of the VIIRS spatial response and band-to-band co-registration (BBR) was measured through intensive pre-launch tests. These measurements were made in the non-aggregated zones near the start (or end) of scan for the I-bands and M-bands and for a limited number of aggregation modes for the DNB in order to test requirement compliance. This paper presents results based on a recently re-processed pre-launch test data. Sensor (detector) spatial impulse responses in the scan direction are parameterized in terms of ground dynamic field of view (GDFOV), horizontal spatial resolution (HSR), modulation transfer function (MTF), ensquared energy (EE) and integrated out-of-pixel (IOOP) spatial response. Results are presented for the non-aggregation, 2-sample and 3-sample aggregation zones for the I-bands and M-bands, and for a limited number of aggregation modes for the DNB. On-orbit GDFOVs measured for the 5 I-bands in the scan direction using a straight bridge are also presented. Band-to-band co-registration (BBR) is quantified using the prelaunch measured band-to-band offsets. These offsets may be expressed as fractions of horizontal sampling intervals (HSIs), detector spatial response parameters GDFOV or HSR. BBR bases on HSIs in the non-aggregation, 2-sample and 3-sample aggregation zones are presented. BBR matrices based on scan direction GDFOV and HSR are compared to the BBR matrix based on HSI in the non-aggregation zone. We demonstrate that BBR based on GDFOV is a better representation of footprint overlap and so this definition should be used in BBR requirement specifications. We propose that HSR not be used as the primary image quality indicator, since we

  3. Making digital phantoms with spectral and spatial light modulators for quantitative applications of hyperspectral optical medical imaging devices

    NASA Astrophysics Data System (ADS)

    Chon, Bonghwan; Tokumasu, Fuyuki; Lee, Ji Youn; Allen, David W.; Rice, Joseph P.; Hwang, Jeeseong

    2015-03-01

    We present a procedure to generate digital phantoms with a hyperspectral image projector (HIP) consisting of two liquid crystal on silicon (LCoS) spatial light modulators (SLMs). The digital phantoms are 3D image data cubes of the spatial distribution of spectrally resolved abundances of intracellular light-absorbing oxy-hemoglobin molecules in single erythrocytes. Spectrally and spatially resolved image data indistinguishable from the real scene may be used as standards to calibrate image sensors and validate image analysis algorithms for their measurement quality, performance consistency, and inter-laboratory comparisons for quantitative biomedical imaging applications.

  4. Spectral sensitivity, spatial resolution and temporal resolution and their implications for conspecific signalling in cleaner shrimp.

    PubMed

    Caves, Eleanor M; Frank, Tamara M; Johnsen, Sönke

    2016-02-01

    Cleaner shrimp (Decapoda) regularly interact with conspecifics and client reef fish, both of which appear colourful and finely patterned to human observers. However, whether cleaner shrimp can perceive the colour patterns of conspecifics and clients is unknown, because cleaner shrimp visual capabilities are unstudied. We quantified spectral sensitivity and temporal resolution using electroretinography (ERG), and spatial resolution using both morphological (inter-ommatidial angle) and behavioural (optomotor) methods in three cleaner shrimp species: Lysmata amboinensis, Ancylomenes pedersoni and Urocaridella antonbruunii. In all three species, we found strong evidence for only a single spectral sensitivity peak of (mean ± s.e.m.) 518 ± 5, 518 ± 2 and 533 ± 3 nm, respectively. Temporal resolution in dark-adapted eyes was 39 ± 1.3, 36 ± 0.6 and 34 ± 1.3 Hz. Spatial resolution was 9.9 ± 0.3, 8.3 ± 0.1 and 11 ± 0.5 deg, respectively, which is low compared with other compound eyes of similar size. Assuming monochromacy, we present approximations of cleaner shrimp perception of both conspecifics and clients, and show that cleaner shrimp visual capabilities are sufficient to detect the outlines of large stimuli, but not to detect the colour patterns of conspecifics or clients, even over short distances. Thus, conspecific viewers have probably not played a role in the evolution of cleaner shrimp appearance; rather, further studies should investigate whether cleaner shrimp colour patterns have evolved to be viewed by client reef fish, many of which possess tri- and tetra-chromatic colour vision and relatively high spatial acuity.

  5. Image slicing with a twist: spatial and spectral Nyquist sampling without anamorphic optics

    NASA Astrophysics Data System (ADS)

    Tecza, Matthias

    2014-07-01

    Integral field spectrographs have become mainstream instruments at modern telescopes because of their efficient way of collecting data-cubes. Image slicer based integral field spectrographs achieve the highest fill-factor on the detector, but due to the need to Nyquist-sample the spectra, their spatial sampling on the sky is rectangular. Using anamorphic pre-optics before the image slicer overcomes this effect further maximising the fill-factor, but introduces optical aberrations, throughput losses, and additional alignment and calibration requirements, compromising overall instrument performance. In this paper I present a concept for an image-slicer that achieves both spatial and spectral Nyquist-sampling without anamorphic pre-optics. Rotating each slitlet by 45° with respect to the dispersion direction, and arranging them into a saw-tooth pseudo-slit, leads to a lozenge shaped sampling element on the sky, however, the centres of the lozenges lie on a regular and square grid, satisfying the Nyquist sampling criterion in both spatial directions.

  6. Absolute Radiometric Calibration of KOMPSAT-3A

    NASA Astrophysics Data System (ADS)

    Ahn, H. Y.; Shin, D. Y.; Kim, J. S.; Seo, D. C.; Choi, C. U.

    2016-06-01

    This paper presents a vicarious radiometric calibration of the Korea Multi-Purpose Satellite-3A (KOMPSAT-3A) performed by the Korea Aerospace Research Institute (KARI) and the Pukyong National University Remote Sensing Group (PKNU RSG) in 2015.The primary stages of this study are summarized as follows: (1) A field campaign to determine radiometric calibrated target fields was undertaken in Mongolia and South Korea. Surface reflectance data obtained in the campaign were input to a radiative transfer code that predicted at-sensor radiance. Through this process, equations and parameters were derived for the KOMPSAT-3A sensor to enable the conversion of calibrated DN to physical units, such as at-sensor radiance or TOA reflectance. (2) To validate the absolute calibration coefficients for the KOMPSAT-3A sensor, we performed a radiometric validation with a comparison of KOMPSAT-3A and Landsat-8 TOA reflectance using one of the six PICS (Libya 4). Correlations between top-of-atmosphere (TOA) radiances and the spectral band responses of the KOMPSAT-3A sensors at the Zuunmod, Mongolia and Goheung, South Korea sites were significant for multispectral bands. The average difference in TOA reflectance between KOMPSAT-3A and Landsat-8 image over the Libya 4, Libya site in the red-green-blue (RGB) region was under 3%, whereas in the NIR band, the TOA reflectance of KOMPSAT-3A was lower than the that of Landsat-8 due to the difference in the band passes of two sensors. The KOMPSAT-3Aensor includes a band pass near 940 nm that can be strongly absorbed by water vapor and therefore displayed low reflectance. Toovercome this, we need to undertake a detailed analysis using rescale methods, such as the spectral bandwidth adjustment factor.

  7. Blast investigation by fast multispectral radiometric analysis

    NASA Astrophysics Data System (ADS)

    Devir, A. D.; Bushlin, Y.; Mendelewicz, I.; Lessin, A. B.; Engel, M.

    2011-06-01

    Knowledge regarding the processes involved in blasts and detonations is required in various applications, e.g. missile interception, blasts of high-explosive materials, final ballistics and IED identification. Blasts release large amount of energy in short time duration. Some part of this energy is released as intense radiation in the optical spectral bands. This paper proposes to measure the blast radiation by a fast multispectral radiometer. The measurement is made, simultaneously, in appropriately chosen spectral bands. These spectral bands provide extensive information on the physical and chemical processes that govern the blast through the time-dependence of the molecular and aerosol contributions to the detonation products. Multi-spectral blast measurements are performed in the visible, SWIR and MWIR spectral bands. Analysis of the cross-correlation between the measured multi-spectral signals gives the time dependence of the temperature, aerosol and gas composition of the blast. Farther analysis of the development of these quantities in time may indicate on the order of the detonation and amount and type of explosive materials. Examples of analysis of measured explosions are presented to demonstrate the power of the suggested fast multispectral radiometric analysis approach.

  8. Closing the terrestrial-planetary remote sensing loop: Spectral, spatial and physical proxies

    NASA Astrophysics Data System (ADS)

    Ramsey, M. S.

    2002-12-01

    The physical and erosional environments on Earth and Mars are clearly very different, however current instruments orbiting each planet offer a unique opportunity for comparative studies. Thermal infrared (TIR) images from the Thermal Emission Imaging System (THEMIS) instrument now returning data from Mars offer the potential of mapping very small regions, with detection limits as low as 500 - 1000 m2. The Earth-orbiting Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument compares favorably to the spectral and spatial resolution of THEMIS and can be used to test spectral analysis models. However, accurate mineral identification using techniques such as linear deconvolution can be hindered by the multispectral resolution of these instruments, the robustness of current spectral libraries, and complicating surface factors such as dust. The accuracy and confidence in such modeling approaches must rely on precursor field and laboratory investigations that develop a methodology for quantitative extraction of mineralogy using scale-dependant modeling, while completely exploring the data sets. The fundamental goal of remote sensing measurements, whether in the laboratory or from space, is to determine the physical and chemical characteristics of the object under study. One technique employed to ascertain the surface mineralogy is spectral deconvolution, which has been used for a variety of scientific problems involving mixture analyses. This methodology is constrained by several assumptions in order to provide meaningful results. Foremost, the approach allows a maximum number of end-members equal to one plus the total number of equations or instrument wavelengths. This becomes a critical limitation in attempting to deconvolve multispectral data using large spectral end-member libraries. In other words, analyses of these data sets requires a robust search algorithm to winnow mineral libraries for the best possible subset of end-member spectra

  9. Radiometric Cross-Calibration of Polar Orbital Sensors Using Geostationary Ocean Color Imager (GOCI)

    NASA Astrophysics Data System (ADS)

    Park, Wook; Won, Joong-Sun

    2012-04-01

    The possibility of radiometric cross-calibration between a Geostationary Ocean Color Image (GOCI) and polar-orbital sensors is discussed. A sensor on a geostationary satellite is useful for the cross-calibration with sensors mounted on polar orbit satellites due to frequent data acquisition. The GOCI has a limitation on precisely measuring the reflectance of land objects because spectral setting of the GOCI is originally designed for ocean monitoring, and therefore GOCI images must be carefully calibrated first with a help of in-situ data to be used as a standard image. Preliminary results from the comparison between the GOCI and MODIS AQUA are presented. Test sites were selected from a snow cover in Baekdu-san (or Mt. Baekdu), a playa and a sand dune in the Inner Mongolia, and snow cover or water (seasonal) in the Hankka Lake. The results showed the GOCI data is good for cross-calibration as defined by spectral differences less than 7% under various conditions (four bands and four different surface conditions) compared with simulated GOCI radiance from MODIS AQUA land bands. Correlation coefficient R2 was over 0.93 in most cases. Scale effect due to surface inhomogeneity and different spatial resolutions between different sensors will be further examined in the near future. The geostationary sensor can be utilized for radiometric cross-calibration of SENTINEL-2.

  10. Spectral and spatial dependence of
diffuse optical signals in response to
peripheral nerve stimulation

    PubMed Central

    Chen, Debbie K.; Erb, M. Kelley; Tong, Yunjie; Yu, Yang; Sassaroli, Angelo; Bergethon, Peter R.; Fantini, Sergio

    2010-01-01

    Using non-invasive, near-infrared spectroscopy we have previously reported optical signals measured at or around peripheral nerves in response to their stimulation. Such optical signals featured amplitudes on the order of 0.1% and peaked about 100 ms after peripheral nerve stimulation in human subjects. Here, we report a study of the spatial and spectral dependence of the optical signals induced by stimulation of the human median and sural nerves, and observe that these optical signals are: (1) unlikely due to either dilation or constriction of blood vessels, (2) not associated with capillary bed hemoglobin, (3) likely due to blood vessel(s) displacement, and (4) unlikely due to fiber-skin optical coupling effects. We conclude that the most probable origin of the optical response to peripheral nerve stimulation is from displacement of blood vessels within the optically probed volume, as a result of muscle twitch in adjacent areas. PMID:21258519

  11. Strain-Induced Spatial and Spectral Isolation of Quantum Emitters in Mono- and Bilayer WSe2

    PubMed Central

    2015-01-01

    Two-dimensional transition metal dichalcogenide semiconductors are intriguing hosts for quantum light sources due to their unique optoelectronic properties. Here, we report that strain gradients, either unintentionally induced or generated by substrate patterning, result in spatially and spectrally isolated quantum emitters in mono- and bilayer WSe2. By correlating localized excitons with localized strain variations, we show that the quantum emitter emission energy can be red-tuned up to a remarkable ∼170 meV. We probe the fine-structure, magneto-optics, and second-order coherence of a strained emitter. These results raise the prospect of strain-engineering quantum emitter properties and deterministically creating arrays of quantum emitters in two-dimensional semiconductors. PMID:26480237

  12. Evaluation of a novel fiber probe for spatially and spectrally resolved reflectance measurements of turbid media

    NASA Astrophysics Data System (ADS)

    Andree, Stefan; Luckmann, Heiko; Reble, Carina; Gersonde, Ingo; Helfmann, Jürgen

    2011-07-01

    A novel fiber probe for spatially resolved reflectance measurements is presented, which uses simultaneously read-out spectrometers for each source-detector separation. Therefore, with this fiber probe and a Monte Carlo simulation, it is possible to determine spectrally resolved absorption and reduced scattering coefficients from various skinsites. The absolute calibration is done by using an integrating sphere but a phantom based calibration procedure was undertaken to compare the results of different calibration techniques. For tissue measurements, a standard SMA adaptor with a one inch diameter face can be used to provide a stable base for placing the probe onto the tissue and the possibility to apply pressure. The evaluation process was carried out by comparing the measured absorption and scattering of silicone and liquid phantoms to their reference values, obtained by integrating sphere spectroscopy. In addition, preliminary skin measurements are presented.

  13. Absolute measurement of spatial and spectral characteristics of bremsstrahlung using the photoexcitation of nuclear isomers

    NASA Astrophysics Data System (ADS)

    Carroll, J. J.; Richmond, D. G.; Sinor, T. W.; Taylor, K. N.; Hong, C.; Standifird, J. D.; Collins, C. B.; Huxel, N.; von Neumann-Cosel, P.; Richter, A.

    1993-08-01

    A method of obtaining absolute, direct measurements of the spatial and spectral characteristics of bremsstrahlung is discussed. This technique, called x-ray activation of nuclei (XAN) is based on the use of well-known photonuclear reactions which populate long-lived nuclear isomers. These populations sample incident photon continua at discrete excitation energies and effectively store this information for convenient retrieval following the irradiation of gram-sized targets. Recently a series of experiments has been conducted which has significantly expanded the available data for the photoexcitation of a wide range of isomers at higher energies. Thus it has become feasible to extend the use of XAN to energies approaching 4 MeV. The utility of this technique is demonstrated by the characterization of bremsstrahlung from the newly installed research linac at the University of Texas at Dallas.

  14. Illumination-invariant recognition of 3D hyperspectral textures using spectral/spatial Gabor filters

    NASA Astrophysics Data System (ADS)

    Bau, Tien C.; Healey, Glenn

    2010-04-01

    We develop a method for the recognition of textures with three-dimensional structure in hyperspectral images. Properties of a texture are captured by a feature vector that is generated by a bank of spectral/spatial Gabor filters. Variation in the illumination and atmospheric conditions is modeled using a subspace of the feature vectors. Since a large bank of filters is used, we develop methods for reducing the dimension of the feature vector that is used to represent a texture. The goal of the dimension-reduction process is to optimize the discriminability of a set of textures. We demonstrate the utility of the approach using experiments with hyperspectral textures of three-dimensional objects that are generated by DIRSIG over a range of conditions.

  15. Spatial representations of temporal and spectral sound cues in human auditory cortex.

    PubMed

    Herdener, Marcus; Esposito, Fabrizio; Scheffler, Klaus; Schneider, Peter; Logothetis, Nikos K; Uludag, Kamil; Kayser, Christoph

    2013-01-01

    Natural and behaviorally relevant sounds are characterized by temporal modulations of their waveforms, which carry important cues for sound segmentation and communication. Still, there is little consensus as to how this temporal information is represented in auditory cortex. Here, by using functional magnetic resonance imaging (fMRI) optimized for studying the auditory system, we report the existence of a topographically ordered spatial representation of temporal sound modulation rates in human auditory cortex. We found a topographically organized sensitivity within auditory cortex to sounds with varying modulation rates, with enhanced responses to lower modulation rates (2 and 4 Hz) on lateral parts of Heschl's gyrus (HG) and faster modulation rates (16 and 32 Hz) on medial HG. The representation of temporal modulation rates was distinct from the representation of sound frequencies (tonotopy) that was orientated roughly orthogonal. Moreover, the combination of probabilistic anatomical maps with a previously proposed functional delineation of auditory fields revealed that the distinct maps of temporal and spectral sound features both prevail within two presumed primary auditory fields hA1 and hR. Our results reveal a topographically ordered representation of temporal sound cues in human primary auditory cortex that is complementary to maps of spectral cues. They thereby enhance our understanding of the functional parcellation and organization of auditory cortical processing.

  16. The role of spatial and spectral resolution on the effectiveness of satellite-based vegetation indices

    NASA Astrophysics Data System (ADS)

    Psomiadis, Emmanouil; Dercas, Nicholas; Dalezios, Nicolas R.; Spyropoulos, Nikolaos V.

    2016-10-01

    Remote Sensing applications are designed to provide farmers with timely crop monitoring and production information. Such information can be used to identify crop needs or health problems and provide solutions for a better crop management. Vegetation indices (VIs) derived from satellite data have been widely used to assess variations in the physiological state and biophysical properties of vegetation. In the present study, the experimental area is located near the village Eleftherion of Larissa Prefecture in the Thessaly Plain, and consisted of two adjacent agricultural fields of cotton and corn. Imagery from WorldView-2 (WV2) satellite platform was obtained from European Space Imaging and Landsat-8 (L8) free of charge data were downloaded from the United States Geological Survey (USGS) archive. The images were selected for a four month span to evaluate continuity with respect to vegetation growth variation. VIs for each satellite platform data such as the Normalized Difference Vegetation Index (NDVI), the Soil-Adjusted Vegetation Index (SAVI) and the Fraction Photosynthetically Radiation (FPAR) were calculated. The comparison of these VIs produced from the two satellite systems with different spatial and spectral resolution was made for each growth stage of the crops and their results were analyzed in order to examine their correlation. Utilizing the WV2 new spectral data, several innovative chlorophyll and vegetation indices were created and evaluated so as to reveal their effectiveness in the detection of problematic plant growth areas. The Green Chlorophyll index appeared to be the most efficient index for the delineation of these areas.

  17. Laser-induced fluorescence imaging of subsurface tissue structures with a volume holographic spatial-spectral imaging system.

    PubMed

    Luo, Yuan; Gelsinger-Austin, Paul J; Watson, Jonathan M; Barbastathis, George; Barton, Jennifer K; Kostuk, Raymond K

    2008-09-15

    A three-dimensional imaging system incorporating multiplexed holographic gratings to visualize fluorescence tissue structures is presented. Holographic gratings formed in volume recording materials such as a phenanthrenquinone poly(methyl methacrylate) photopolymer have narrowband angular and spectral transmittance filtering properties that enable obtaining spatial-spectral information within an object. We demonstrate this imaging system's ability to obtain multiple depth-resolved fluorescence images simultaneously.

  18. Radiometric Navigation Update

    NASA Astrophysics Data System (ADS)

    Nettles, James L.; Witsmeer, A. James; Wilt, Robert E.

    1980-12-01

    Boeing Aerospace Company (BAC) of Seattle, Washington and Sperry Microwave Electronics of Clearwater, Florida have developed a multiple-beam radiometric navigation update system. This paper describes the system design, flight test program, and preliminary results. The system was designed and its performance evaluated using analytically derived formulas for performance measures and detailed Monte Carlo simulations. As a result BAC recommended a five or seven fixed beam radiometer. Sperry built a seven-beam, 35 GHz radiometer which BAC flight tested in 1979 to demonstrate its effectiveness over a variety of test scenes under various environmental conditions. Four scenes were selected for the flight test varying from land-water to highly forested regions. Preliminary analysis of the flight test results confirm the expected performance improvement over the single-fixed-beam system tested in 1975. This approach to a terrain sensing millimeter wave radiometer would be applicable to low altitude penetrating aircraft. The system is low cost, with no moving parts; low volume, requiring only a single receiver with small wide-beam antennas; and stealthy, being completely passive. Radiometry can also be complementary to todays terrain correlation approach since flat areas usually contain a maximum of cultural features; where one system works poorly the other works well. This test program provides a data base for studying a wide variety of pattern matching and correlation algorithms, with and without attitude compensation, and using various subsets of the full seven-beam combination.

  19. ATLID receiving spatial and spectral filtering units: design and associated performances

    NASA Astrophysics Data System (ADS)

    Vaché, Maxime; de Saint Seine, Diego; Leblay, Pierrick; Hélière, Arnaud; Pereira Do Carmo, João.; Berlioz, Philippe; Archer, Julien

    2015-09-01

    ATLID (ATmospheric LIDar) is one of the four key instruments of EarthCARE (Earth Clouds, Aerosols and Radiations Explorer) satellite. It is a program of and funded by the European Space Agency and under prime contractorship of Airbus Defence and Space. ATLID is dedicated to the understanding of aerosols and clouds contribution to earth climate. It is an atmospheric LIDAR that measures the emitted 354.8nm ultraviolet laser which is backscattered by the atmosphere. The molecules and the particles have different optical signatures and can consequently be distinguished thanks to polarization analyses and spectral filtering of the backscattered signal. The following optical units of ATLID receiver chain directly contribute to this function : after ATLID afocal telescope, the CAS-OA, the Optical Assembly of the Co Alignment Sensor, samples and images the beam on the CAS sensor in order to optimize the alignment of transmitting and receiving telescopes. The beam goes through the BF sub-assemblies, the Blocking Filter which has two filtering functions: (1) spatial with the ERO-BF, which is a Kepler afocal spatial filtering module that defines the instrument field of view and blocks the background and straylight out of the useful field of view; (2) spectral with the ERO-EFO, the Entrance Filtering Optic, which is mainly composed of a very narrow bandpass filter with a high rejection factor. This filter rejects the background from the useful signal and contributes to increase the signal-to-noise ratio. The EFO also allows an on-ground adjustment of the orientation of the linear polarization of the input beam. After filtering and polarization adjustment, the beam is injected in several optical fibers and transported to the instrument detectors. This last transport function is done by the FCA, the Fiber Coupler Assembly. This paper presents the flight models of the previously described units, details the opto-mechanical design, and reviews the main achieved performances with a

  20. A hybrid discontinuous finite element-spectral nodal method for slab-geometry transport problems without spatial truncation error

    SciTech Connect

    Barros, R.C. de

    1995-12-31

    Described here is a hybrid discontinuous finite element-spectral nodal method for slab-geometry one-speed transport problems without spatial truncation error. For the angular approximation the author used a linear discontinuous (LD) expansion for the angular flux inside each of the N elements of a uniform angular grid. This procedure yields the LD{sub N} equations that is solved numerically using the Spectral Green`s Function (SGF) method with the one-node block inversion (NBI) iterative scheme. The SGF method generates numerical solutions for the LD{sub N} equations that are completely free from spatial approximations. Numerical results are given to illustrate the methods accuracy.

  1. Spatially Complete Global Spectral Surface Albedos: Value-Added Datasets Derived from Terra MODIS Land Products

    NASA Technical Reports Server (NTRS)

    Moody, Eric G.; King, Michael D.; Platnick, Steven; Schaaf, Crystal B.; Gao, Feng

    2004-01-01

    Land surface albedo is an important parameter in describing the radiative properties of the earth s surface as it represents the amount of incoming solar radiation that is reflected from the surface. The amount and type of vegetation of the surface dramatically alters the amount of radiation that is reflected; for example, croplands that contain leafy vegetation will reflect radiation very differently than blacktop associated with urban areas. In addition, since vegetation goes through a growth, or phenological, cycle, the amount of radiation that is reflected changes over the course of a year. As a result, albedo is both temporally and spatially dependant upon global location as there is a distribution of vegetated surface types and growing conditions. Land surface albedo is critical for a wide variety of earth system research projects including but not restricted to remote sensing of atmospheric aerosol and cloud properties from space, ground-based analysis of aerosol optical properties from surface-based sun/sky radiometers, biophysically-based land surface modeling of the exchange of energy, water, momentum, and carbon for various land use categories, and surface energy balance studies. These projects require proper representation of the surface albedo s spatial, spectral, and temporal variations, however, these representations are often lacking in datasets prior to the latest generation of land surface albedo products.

  2. The influence of spectral and spatial resolution in classification approaches: Landsat TM data vs. Hyperspectral data

    NASA Astrophysics Data System (ADS)

    Rodríguez-Galiano, Víctor; Garcia-Soldado, Maria José; Chica-Olmo, Mario

    The importance of accurate and timely information describing the nature and extent of land and natural resources is increasing especially in rapidly growing metropolitan areas. While metropolitan area decision makers are in constant need of current geospatial information on patterns and trends in land cover and land use, relatively little researchers has investigated the influence of the satellite data resolution for monitoring geo-enviromental information. In this research a suite of remote sensing and GIS techniques is applied in a land use mapping study. The main task is to asses the influence of the spatial and spectral resolution in the separability between classes and in the classificatiońs accuracy. This study has been focused in a very dynamical area with respect to land use, located in the province of Granada (SE of Spain). The classifications results of the Airborne Hyperspectral Scanner (AHS, Daedalus Enterprise Inc., WA, EEUU) at different spatial resolutions: 2, 4 and 6 m and Landsat 5 TM data have been compared.

  3. Effects of spatial resolution and spectral purity on transvenous coronary angiography images

    SciTech Connect

    Chapman, D.; Thomlinson, W.; Gumer, N.F.

    1994-11-01

    Measurements have been made on the National Synchrotron Light Source (NSLS) Coronary Angiography X17B2 beamline under ideal and real imaging conditions to investigate the optimal imaging conditions for spatial resolution and spectral purity. The spatial resolution tests were performed using two multielement Si(Li) detectors (600 element, 0.5mm, pixel-pixel spacing; 1200 element, 0.25mm pixel-pixel spacing. Images were taken of phantoms containing iodine contrast agent over a wide range of incident beam absorption conditions. Patient images were also obtained using the same viewing projection with both detectors. Harmonics present in the imaging beam can be reduced by operating the superconducting wiggler source at reduced field strength. At regions of high absorption in the patient, the harmonics present can contribute to the detected signal. Iodine phantom images were obtained at a wiggler field strength of 3 Tesla (E{sub c}=13.3keV) and 4 Tesla (E{sub c}= I 7.8keV) for comparison. As before, patient images were obtained using the same projection at both wiggler fields. Results of the detector resolution and wiggler eld measurements will be presented for the phantoms as well as the patient scans.

  4. The Circumstellar Environment of T Tauri S at High Spatial and Spectral Resolution

    NASA Astrophysics Data System (ADS)

    Duchêne, G.; Ghez, A. M.; McCabe, C.; Ceccarelli, C.

    2005-08-01

    We have obtained the first high spatial (0.05") and spectral (R~35,000) resolution 2 μm spectrum of the T Tau S tight binary system using adaptive optics on the Keck II telescope. We have also obtained the first 3.8 and 4.7 μm images that resolve the three components of the T Tau multiple system, as well as new 1.6 and 2.2 μm images. Together with its very red near-infrared colors, the spectrum of T Tau Sb shows that this T Tauri star is extincted by a roughly constant extinction of AV~15 mag, which is probably the 0.7"×0.5" circumbinary structure recently observed in absorption in the ultraviolet. T Tau Sa, which is also observed through this screen and is actively accreting, further possesses a small edge-on disk that is evidenced by warm (390 K), narrow overtone CO rovibrational absorption features in our spectrum. We find that T Tau Sa is most likely an intermediate-mass star surrounded by a semitransparent 2-3 AU radius disk whose asymmetries and short Keplerian rotation explain the large photometric variability of the source on relatively short timescales. We also show that molecular hydrogen emission exclusively arises from the gas that surrounds T Tau S and that its spatial and kinematic structure, while providing suggestive evidence of a jetlike structure, is highly complex.

  5. a Comparison Study of Different Marker Selection Methods for Spectral-Spatial Classification of Hyperspectral Images

    NASA Astrophysics Data System (ADS)

    Akbari, D.; Safari, A. R.; Homayouni, S.; Khazai, S.

    2015-12-01

    An effective approach based on the Minimum Spanning Forest (MSF), grown from automatically selected markers using Support Vector Machines (SVM), has been proposed for spectral-spatial classification of hyperspectral images by Tarabalka et al. This paper aims at improving this approach by using image segmentation to integrate the spatial information into marker selection process. In this study, the markers are extracted from the classification maps, obtained by both SVM and segmentation algorithms, and then are used to build the MSF. The segmentation algorithms are the watershed, expectation maximization (EM) and hierarchical clustering. These algorithms are used in parallel and independently to segment the image. Moreover, the pixels of each class, with the largest population in the classification map, are kept for each region of the segmentation map. Lastly, the most reliable classified pixels are chosen from among the exiting pixels as markers. Two benchmark urban hyperspectral datasets are used for evaluation: Washington DC Mall and Berlin. The results of our experiments indicate that, compared to the original MSF approach, the marker selection using segmentation algorithms leads in more accurate classification maps.

  6. Insights into the content and spatial distribution of dust from the integrated spectral properties of galaxies

    NASA Astrophysics Data System (ADS)

    Chevallard, J.; Charlot, S.; Wandelt, B.; Wild, V.

    2013-07-01

    We present a new approach to investigate the content and spatial distribution of dust in structurally unresolved star-forming galaxies from the observed dependence of integrated spectral properties on galaxy inclination. Motivated by the observation that different stellar populations reside in different spatial components of nearby star-forming galaxies, we develop an innovative combination of generic models of radiative transfer in dusty media with a prescription for the spectral evolution of galaxies, via the association of different geometric components of galaxies with stars in different age ranges. We start by showing that a wide range of radiative transfer models all predict a quasi-universal relation between slope of the attenuation curve at any wavelength, from the ultraviolet to the near-infrared, and V-band attenuation optical depth in the diffuse interstellar medium (ISM), at all galaxy inclinations. This relation predicts steeper (shallower) dust attenuation curves than both the Calzetti and Milky Way curves at small (large) attenuation optical depths, which implies that geometry and orientation effects have a stronger influence on the shape of the attenuation curve than changes in the optical properties of dust grains. We use our new, combined radiative transfer and spectral evolution model to interpret the observed dependence of the Hα/Hβ ratio and ugrizYJH attenuation curve on inclination in a sample of about 23 000 nearby star-forming galaxies, which we correct for systematic biases by developing a general method based on importance sampling. From the exploration of the model parameter space by means of a Bayesian Markov chain Monte Carlo technique, we measure the central face-on B-band optical depth of this sample to be τB⊥ ≈ 1.8 ± 0.2 (corresponding to an angle-averaged {< hat{τ}^ISM_V> _θ }≈ 0.3). We also quantify the enhanced optical depth towards newly formed stars in their birth clouds, finding this to be significantly larger in

  7. High Spectral and Spatial Resolution Near-IR Spectroscopy of M1-92

    NASA Astrophysics Data System (ADS)

    Trammell, S. R.; Goodrich, R. W.

    1997-05-01

    We present high spectral and spatial resolution near-IR spectroscopy of the bipolar proto-planetary nebula M1-92. The spectra were obtained using the high resolution spectrograph, CSHELL, at the NASA Infrared Telescope Facility on Mauna Kea. The goal of this project was to spatially resolve the location of the H_2 emission present in this object and to determine its relative velocity as a function of nebular position. Previous optical spectropolarimetry of M1-92 revealed that the line emission seen in the bipolar lobes is indicative of shock heating with V_s = 40 - 100 km s(-1) (Trammell et al. 1993). Subsequent high resolution optical spectroscopy demonstrated that this shock emission is associated with a high velocity outflow (Solf 1994). Narrow-band HST images of this object show a highly collimated outflow originating near the central star and impacting the bipolar lobes (Trammell and Goodrich 1996). Using a 1arcsec slit placed along the bipolar axis, we mapped the velocity field of the Br gamma and H_2 2.122 micron emission lines in M1-92. In both cases, high velocity components (> 100 km s(-1) ) of emission are evident. The high velocity components of emission are co-spatial with the collimated outflow seen in the lobes of M1-92 in the HST images. Further, the outflow velocities derived for the near-IR emission lines are consistent with those estimated from the optical emission line ratios and found using optical spectroscopy. These results suggest that the near-IR H_2 emission is associated with the collimated outflow seen in the lobes of M1-92. We discuss several mechanisms that could be responsible for producing the kinematic features observed in M1-92, in particular the action of a precessing, episodic jet.

  8. The spatial, spectral and polarization properties of solar flare X-ray sources

    NASA Astrophysics Data System (ADS)

    Jeffrey, Natasha L. S.

    2014-12-01

    X-rays are a valuable diagnostic tool for the study of high energy accelerated electrons. Bremsstrahlung X-rays produced by, and directly related to, high energy electrons accelerated during a flare, provide a powerful diagnostic tool for determining both the properties of the accelerated electron distribution, and of the flaring coronal and chromospheric plasmas. This thesis is specifically concerned with the study of spatial, spectral and polarization properties of solar flare X-ray sources via both modelling and X-ray observations using the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Firstly, a new model is presented, accounting for finite temperature, pitch angle scattering and initial pitch angle injection. This is developed to accurately infer the properties of the acceleration region from the observations of dense coronal X-ray sources. Moreover, examining how the spatial properties of dense coronal X-ray sources change in time, interesting trends in length, width, position, number density and thermal pressure are found and the possible causes for such changes are discussed. Further analysis of data in combination with the modelling of X-ray transport in the photosphere, allows changes in X-ray source positions and sizes due to the X-ray albedo effect to be deduced. Finally, it is shown, for the first time, how the presence of a photospheric X-ray albedo component produces a spatially resolvable polarization pattern across a hard X-ray (HXR) source. It is demonstrated how changes in the degree and direction of polarization across a single HXR source can be used to determine the anisotropy of the radiating electron distribution.

  9. Uncooled radiometric camera performance

    NASA Astrophysics Data System (ADS)

    Meyer, Bill; Hoelter, T.

    1998-07-01

    Thermal imaging equipment utilizing microbolometer detectors operating at room temperature has found widespread acceptance in both military and commercial applications. Uncooled camera products are becoming effective solutions to applications currently using traditional, photonic infrared sensors. The reduced power consumption and decreased mechanical complexity offered by uncooled cameras have realized highly reliable, low-cost, hand-held instruments. Initially these instruments displayed only relative temperature differences which limited their usefulness in applications such as Thermography. Radiometrically calibrated microbolometer instruments are now available. The ExplorIR Thermography camera leverages the technology developed for Raytheon Systems Company's first production microbolometer imaging camera, the Sentinel. The ExplorIR camera has a demonstrated temperature measurement accuracy of 4 degrees Celsius or 4% of the measured value (whichever is greater) over scene temperatures ranges of minus 20 degrees Celsius to 300 degrees Celsius (minus 20 degrees Celsius to 900 degrees Celsius for extended range models) and camera environmental temperatures of minus 10 degrees Celsius to 40 degrees Celsius. Direct temperature measurement with high resolution video imaging creates some unique challenges when using uncooled detectors. A temperature controlled, field-of-view limiting aperture (cold shield) is not typically included in the small volume dewars used for uncooled detector packages. The lack of a field-of-view shield allows a significant amount of extraneous radiation from the dewar walls and lens body to affect the sensor operation. In addition, the transmission of the Germanium lens elements is a function of ambient temperature. The ExplorIR camera design compensates for these environmental effects while maintaining the accuracy and dynamic range required by today's predictive maintenance and condition monitoring markets.

  10. High spectral and spatial resolution spectroscopy of YSOs with a silicon grism and adaptive optics

    NASA Astrophysics Data System (ADS)

    Ge, J.; Lloyd, J. P.; Gavel, D.; Macintosh, B.; Max, C. E.; Ciarlo, D.; Kuzmenko, P.; Graham, J. R.

    2000-12-01

    We have obtained complete K band spectra of a total of 6 T Tauri and Ae/Be stars and their close companions at a spectral resolution of R ≈ 5000 using a silicon grism at the Lick 3m telescope. These results represent our first scientific observations conducted by the high resolution silicon grisms. Coupled with the LLNL adaptive optics system, a spatial resolution of 0.2 arcsec was achieved to allow observations of the companions with separations between 0.3-1.3 arcsec. The complete wavelength coverage was achieved by placing 16 cross-dispersed echelle orders on a 256x256 HgCdTe array with the silicon grism operating on high diffraction orders and a low dispersing CaF2 grism as a cross-disperser. High spectral resolution observations allow us to characterize each of the companions. Analysis of the spectra of these YSOs will be reported. The observations also allow us to measure the optical performance of the second generation of silicon grisms made with the techniques developed in early 2000. The new silicon grism has a peak efficiency of 45% and scattered light of ~ 8% in the K band. New techniques have been developed at Penn State to further reduce scattered light in the K band (Bernecker et al. this meeting) and are being applied in fabricating the third generation of silicon grisms for scientific observations. Fabrication of the silicon grisms and work on the Lick adaptive optics system was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-ENG-48. Graham and Lloyd were also supported by the Center for Adaptive Optics under the STC Program of the National Science Foundation, Agreement No. AST-9876783

  11. Radiometric sensor performance model including atmospheric and IR clutter effects

    NASA Astrophysics Data System (ADS)

    Richter, Rudolf; Davis, Joel S.; Duggin, Michael J.

    1997-06-01

    The computer code SENSAT developed for radiometric investigations in remote sensing was extended to include two statistical clutter models of infrared background and the prediction of the target detection probability. The first one is based on the standard deviation of scene clutter estimated from scene data, the second one is based on the power spectral density of different classes of IR background as a function of temporal or spatial frequency. The overall code consists of modules describing the optoelectronic sensor (optics, detector, signal processor), a radiative transfer code (MODTRAN) to include the atmospheric effects, and the scene module consisting of target and background. The scene is evaluated for a certain pixel at a time. However, a sequence of pixels can be simulated by varying the range, view angle, atmospheric condition, or the clutter level. The target consists of one or two subpixel surface elements, the remaining part of the pixels represents background. Multiple paths, e.g. sun-ground-target-sensor, can also be selected. An expert system, based upon the IDL language, provides user-friendly input menus, performs consistency checks, and submits the required MODTRAN and SENSAT runs. A sample case of the detection probability of a sub-pixel target in a marine cluttered background is discussed.

  12. Improved classification accuracy of powdery mildew infection levels of wine grapes by spatial-spectral analysis of hyperspectral images.

    PubMed

    Knauer, Uwe; Matros, Andrea; Petrovic, Tijana; Zanker, Timothy; Scott, Eileen S; Seiffert, Udo

    2017-01-01

    Hyperspectral imaging is an emerging means of assessing plant vitality, stress parameters, nutrition status, and diseases. Extraction of target values from the high-dimensional datasets either relies on pixel-wise processing of the full spectral information, appropriate selection of individual bands, or calculation of spectral indices. Limitations of such approaches are reduced classification accuracy, reduced robustness due to spatial variation of the spectral information across the surface of the objects measured as well as a loss of information intrinsic to band selection and use of spectral indices. In this paper we present an improved spatial-spectral segmentation approach for the analysis of hyperspectral imaging data and its application for the prediction of powdery mildew infection levels (disease severity) of intact Chardonnay grape bunches shortly before veraison. Instead of calculating texture features (spatial features) for the huge number of spectral bands independently, dimensionality reduction by means of Linear Discriminant Analysis (LDA) was applied first to derive a few descriptive image bands. Subsequent classification was based on modified Random Forest classifiers and selective extraction of texture parameters from the integral image representation of the image bands generated. Dimensionality reduction, integral images, and the selective feature extraction led to improved classification accuracies of up to [Formula: see text] for detached berries used as a reference sample (training dataset). Our approach was validated by predicting infection levels for a sample of 30 intact bunches. Classification accuracy improved with the number of decision trees of the Random Forest classifier. These results corresponded with qPCR results. An accuracy of 0.87 was achieved in classification of healthy, infected, and severely diseased bunches. However, discrimination between visually healthy and infected bunches proved to be challenging for a few samples

  13. High spatial and spectral resolution near-infrared mapping of Europa with ESO/VLT/ SINFONI

    NASA Astrophysics Data System (ADS)

    Ligier, Nicolas; Carter, John; Poulet, François; Langevin, Yves; Dumas, Christophe; Gourgeot, Florian

    2014-11-01

    Europa is a major exobiological target of interest owing to the possibility of a sub-surface briny ocean deeply buried under a water ice dominated crust several km thick (Dalton et al., 2010). The upcoming ESA L-class mission JUICE to the Jupiter system and its ambitious payload will address this question, in particular through compositional remote sensing in the near-infrared (MAJIS) and visible (MAJIS and JANUS) wavelength range.In order to improve our knowledge mainly acquired by the instrument NIMS on the Galileo spacecraft, we have started a compositional mapping campaign of the icy moons using adaptive optics on ground-based observations from the Very Large Telescope (VLT) in Chile. Thanks to five nights of observation on the integral field spectrograph SINFONI, we have obtained spatially resolved spectra of nearly the entire surface of Europa, with a spectral resolution of 0.5 nm in the wavelength range 1.48-2.42 μm for a pixel scale of 12.5 by 25 m.a.s, equivalent to 35 by 70 km on Europa’s surface.In this wavelength range, the spectra are generally dominated by crystalline and amorphous water-ice absorption features, but the distorted and asymmetric aspect of the 2.0 μm water-ice band on Europa’s leading side confirms the presence of non-ice minerals such as sulfuric acid hydrate (Carlson et al., 2005) and magnesium sulfates such as epsomite (MgSO4 - 7H2O) (Brown et al., 2013).Our first analysis reveals that the maps of the ice-water bands at 1.65 μm and 2.0 μm are, as expected, dominated by the leading/trailing effect, but also well correlated to well-identified geological structures as Pwyll Crater and Tara Regio. Global maps of relevant spectral parameters will be presented so as to showcase the spectral inhomogeneity of the surface of Europa for both major and minor signatures. No narrow signature, which could indicate the presence of material of exobiological interest, has been so far detected in this complex data set. By the time of the

  14. A spectral method for numerical elastodynamic fracture analysis without spatial replication of the rupture event

    NASA Astrophysics Data System (ADS)

    Cochard, Alain; Rice, James R.

    1997-08-01

    Perrin et al. (1995) and Geubelle and Rice (1995) have introduced a spectral method for numerical solution of two- and three-dimensional elastodynamic fracture problems. The method applies for ruptures confined to a plane separating homogeneous elastic half spaces. In this method, the physical variables, such as the traction components of stress and displacement discontinuity on the rupture plane, are represented as Fourier series in space with time-dependent coefficients. An analytical solution is found for each Fourier mode, in that each Fourier coefficient for stress is expressed by the time convolution of the corresponding coefficient for displacement with a convolution kernel specific to the rupture mode. Once the 2D formulation of the method is known, the method is readily generalizable to 3D problems in that it involves only linear combinations of the convolution kernels found for each rupture mode in 2D. This conceptual simplicity has, however, a major drawback : due to the Fourier series representations of the physical variables, the problem solved is in fact an infinite and periodic replication of rupture events on the fracture plane. So, in order to study the evolution of a single rupture, one has to use a spatial period large enough in order that the waves coming from the replication cracks do not enter the zone of interest during the time duration studied, or provide negligible stress alteration when they do arrive. We show here how to rigorously offset this defect while retaining the modal independence. Once expressed in the spatial domain, the method amounts to truncating in space the space-time convolution kernels, in a manner that provides an exact evaluation for all positions within the rupture domain (where the constitutive law between stress and displacement discontinuity is to be imposed), but not outside. In order for the method to be identical in structure to the method of Perrin et al. (1995) and Geubelle and Rice (1995), the period of the

  15. Dissecting galaxies: spatial and spectral separation of emission excited by star formation and AGN activity

    NASA Astrophysics Data System (ADS)

    Davies, Rebecca L.; Groves, Brent; Kewley, Lisa J.; Dopita, Michael A.; Hampton, Elise J.; Shastri, Prajval; Scharwächter, Julia; Sutherland, Ralph; Kharb, Preeti; Bhatt, Harish; Jin, Chichuan; Banfield, Julie; Zaw, Ingyin; James, Bethan; Juneau, Stéphanie; Srivastava, Shweta

    2016-10-01

    The optical spectra of Seyfert galaxies are often dominated by emission lines excited by both star formation and active galactic nucleus (AGN) activity. Standard calibrations (such as for the star formation rate) are not applicable to such composite (mixed) spectra. In this paper, we describe how integral field data can be used to spectrally and spatially separate emission associated with star formation from emission associated with accretion on to an AGN. We demonstrate our method using integral field data for two AGN host galaxies (NGC 5728 and NGC 7679) from the Siding Spring Southern Seyfert Spectroscopic Snapshot Survey (S7). The spectra of NGC 5728 and NGC 7679 form clear sequences of AGN fraction on standard emission line ratio diagnostic diagrams. We show that the emission line luminosities of the majority (>85 per cent) of spectra along each AGN fraction sequence can be reproduced by linear superpositions of the emission line luminosities of one AGN dominated spectrum and one star formation dominated spectrum. We separate the Hα, Hβ, [N II]λ6583, [S II]λλ6716, 6731, [O III]λ5007 and [O II]λλ3726, 3729 luminosities of every spaxel into contributions from star formation and AGN activity. The decomposed emission line images are used to derive the star formation rates and AGN bolometric luminosities for NGC 5728 and NGC 7679. Our calculated values are mostly consistent with independent estimates from data at other wavelengths. The recovered star-forming and AGN components also have distinct spatial distributions which trace structures seen in high-resolution imaging of the galaxies, providing independent confirmation that our decomposition has been successful.

  16. Spatial-Spectral Studies of Cometary Volatiles and the Physical Environment of Inner Cometary Atmospheres

    NASA Astrophysics Data System (ADS)

    Bonev, Boncho P.; Fougere, Nicolas; Villanueva, Geronimo L.; Mumma, Michael J.; Combi, Michael R.; DiSanti, Michael A.; Paganini, Lucas; Cordiner, Martin; Gibb, Erika L.; Milam, Stefanie N.

    2015-11-01

    How is water released in comets - directly from the nucleus versus sublimation from icy grains in the coma? How common and how prevalent are icy grains as a source of gas-phase water (and other volatiles) among the active comet population? These questions are being addressed through synergy between spatial-spectral studies of native volatiles in comets and the physical models tested against them. This synergy is extending the state-of-the-art in both domains. Ground-based near-IR spectroscopy (Keck, NASA IRTF, and ESO VLT) allowed measurements of spatially resolved inner coma temperatures and column densities for H2O - the most abundant volatile in the coma. These measurements motivated the inclusion of new physics in the models. The evolved models now open new questions and trigger improvement in the accuracy of measured temperature profiles, most recently extended to other molecules (HCN in the near-IR) and to other wavelength domains (CH3OH, through ALMA; S. Milam et al., this meeting). The net result is deeper quantitative insight into the competition among processes that cause heating and cooling of the coma and into the prevalent mechanism(s) for release of native volatiles in the gas phase.The same inner-coma modeling formalisms are used to interpret both the environment of Rosetta's mission target (67P/Churyumov-Gerasimenko) and those from the ground-based observations reported here (Combi et al. 2015, LPSC, #1714; Fougere et al., this meeting). While ground-based spectroscopy offers less detail than in-situ missions, it can probe the comae of many comets that may differ greatly from one another and from Rosetta's target, thereby assessing the extent to which the inner-coma environment of 67P is unique, and how it relates to other comets.We gratefully acknowledge support from NASA Planetary Atmospheres, Solar System Workings, Planetary Astronomy, and Astrobiology programs, and from NSF Astronomy and Astrophysics Research Grants program.

  17. A Detailed Spatial and Spectral Study of Synchrotron X-rays from Supernova Remnants with Chandra

    NASA Astrophysics Data System (ADS)

    Bamba, Aya

    2004-01-01

    We present the first results of a systematic spatial and spectral X-ray study of small scale structures on the shock of five supernova remnants (Cas A, Kepler, Tycho, SN 1006, and RCW 86) and a super bubble (30 Dor C), with excellent spatial resolution of the Chandra X-ray observatory. All targets have synchrotron X-ray emission which concentrate on a very narrow region of the outer edge of the shock. The scale length of the region emitting synchrotron X-rays is incredibly small, less than 1% of the radius of the system both in the upstream and the downstream, in which smaller lengths are seen in the upstream than in the downstream. Together with the information of wide band spectra from radio to X-ray, both age-limited and loss-limited assumptions are checked for the acceleration history of all the SNRs. We found a possible magnetic field strength and configuration, and the maximum energy of accelerated electrons have been estimated for each target. The perpendicular magnetic field to the shock normal is accepted in all SNR cases, with highly turbulent magnetic field downstream. Comparing the samples, we found that the scale length of shocks grows as its age increases, in the same rate of Sedov similar solution for upstream (∝ t4/5) and in a faster rate for downstream (∝ t1/2). The energy density of magnetic field and cosmic rays evolve keeping an equipartition with the thermal and kinetic energies of the shock (∝ t-6/5) under the assumption that the system is in the age-limited case, implying that there are strong energy interaction between kinetic, thermal, magnetic field, and cosmic ray energy densities. The magnetic field is always near to perpendicular. These are the first results to estimate observationally the magnetic field and its direction, energy density of magnetic field and cosmic rays, and their evolutions.

  18. A Spatial and Spectral Study of Nonthermal Filaments in Historical Supernova Remnants: Observational Results with Chandra

    NASA Astrophysics Data System (ADS)

    Bamba, Aya; Yamazaki, Ryo; Yoshida, Tatsuo; Terasawa, Toshio; Koyama, Katsuji

    2005-03-01

    The outer shells of young supernova remnants (SNRs) are the most plausible acceleration sites of high-energy electrons with the diffusive shock acceleration (DSA) mechanism. We studied spatial and spectral properties close to the shock fronts in four historical SNRs (Cas A, Kepler's remnant, Tycho's remnant, and RCW 86) with excellent spatial resolution of Chandra. In all of the SNRs, hard X-ray emissions were found on the rims of the SNRs, which concentrate in very narrow regions (so-called filaments); apparent scale widths on the upstream side are below or on the order of the point-spread function of Chandra, while they are 0.5"-40" (0.01-0.4 pc) on the downstream side with most reliable distances. The spectra of these filaments can be fitted with both thermal and nonthermal (power law and SRCUT) models. The former requires unrealistic high temperature (>~2 keV) and low abundances (<~1 solar) for emission from young SNRs and may be thus unlikely. The latter reproduces the spectra with best-fit photon indices of 2.1-3.8, or roll-off frequencies of (0.1-28)×1017 Hz, which reminds us of the synchrotron emission from electrons accelerated via DSA. We consider various physical parameters as functions of the SNR age, including the previous results on SN 1006; the filament width on the downstream side increases with the SNR age, and the spectrum becomes softer, keeping a nonthermal feature. It was also found that a function, that is, the roll-off frequency divided by the square of the scale width on the downstream side, shows negative correlation with the age, which might provide us some information on the DSA theory.

  19. Spatial Variations of PAH Properties in M17SW Revealed by Spitzer/IRS Spectral Mapping

    NASA Astrophysics Data System (ADS)

    Yamagishi, M.; Kaneda, H.; Ishihara, D.; Oyabu, S.; Suzuki, T.; Onaka, T.; Nagayama, T.; Umemoto, T.; Minamidani, T.; Nishimura, A.; Matsuo, M.; Fujita, S.; Tsuda, Y.; Kohno, M.; Ohashi, S.

    2016-12-01

    We present Spitzer/IRS mid-infrared spectral maps of the Galactic star-forming region M17 as well as IRSF/SIRIUS Brγ and Nobeyama 45 m/FOREST 13CO (J = 1-0) maps. The spectra show prominent features due to polycyclic aromatic hydrocarbons (PAHs) at wavelengths of 6.2, 7.7, 8.6, 11.3, 12.0, 12.7, 13.5, and 14.2 μm. We find that the PAH emission features are bright in the region between the H ii region traced by Brγ and the molecular cloud traced by 13CO, supporting that the PAH emission originates mostly from photo-dissociation regions. Based on the spatially resolved Spitzer/IRS maps, we examine spatial variations of the PAH properties in detail. As a result, we find that the interband ratio of PAH 7.7 μm/PAH 11.3 μm varies locally near M17SW, but rather independently of the distance from the OB stars in M17, suggesting that the degree of PAH ionization is mainly controlled by local conditions rather than the global UV environments determined by the OB stars in M17. We also find that the interband ratios of the PAH 12.0 μm, 12.7 μm, 13.5 μm, and 14.2 μm features to the PAH 11.3 μm feature are high near the M17 center, which suggests structural changes of PAHs through processing due to intense UV radiation, producing abundant edgy irregular PAHs near the M17 center.

  20. Landsat-5 TM reflective-band absolute radiometric calibration

    USGS Publications Warehouse

    Chander, G.; Helder, D.L.; Markham, B.L.; Dewald, J.D.; Kaita, E.; Thome, K.J.; Micijevic, E.; Ruggles, T.A.

    2004-01-01

    The Landsat-5 Thematic Mapper (TM) sensor provides the longest running continuous dataset of moderate spatial resolution remote sensing imagery, dating back to its launch in March 1984. Historically, the radiometric calibration procedure for this imagery used the instrument's response to the Internal Calibrator (IC) on a scene-by-scene basis to determine the gain and offset of each detector. Due to observed degradations in the IC, a new procedure was implemented for U.S.-processed data in May 2003. This new calibration procedure is based on a lifetime radiometric calibration model for the instrument's reflective bands (1-5 and 7) and is derived, in part, from the IC response without the related degradation effects and is tied to the cross calibration with the Landsat-7 Enhanced Thematic Mapper Plus. Reflective-band absolute radiometric accuracy of the instrument tends to be on the order of 7% to 10%, based on a variety of calibration methods.

  1. Radiometric framework for image mosaicking.

    PubMed

    Litvinov, Anatoly; Schechner, Yoav Y

    2005-05-01

    Nonuniform exposures often affect imaging systems, e.g., owing to vignetting. Moreover, the sensor's radiometric response may be nonlinear. These characteristics hinder photometric measurements. They are particularly annoying in image mosaicking, in which images are stitched to enhance the field of view. Mosaics suffer from seams stemming from radiometric inconsistencies between raw images. Prior methods feathered the seams but did not address their root cause. We handle these problems in a unified framework. We suggest a method for simultaneously estimating the radiometric response and the camera nonuniformity, based on a frame sequence acquired during camera motion. The estimated functions are then compensated for. This permits image mosaicking, in which no seams are apparent. There is no need to resort to dedicated seam-feathering methods. Fundamental ambiguities associated with this estimation problem are stated.

  2. Airborne microwave radiometric imaging system

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Zhang, Zuyin; Chen, Zhengwen

    1998-08-01

    A dual channel Airborne Microwave Radiometric Imaging system (AMRI) was designed and constructed for regional environment mapping. The system operates at 35GHz, which collects radiation at horizontal and vertical polarized. It runs at mechanical conical scanning with 45 degrees incidence angle. Two Cassegrain antennas with 1.5 degrees 3 dB beamwidth scan the scene alternately and two pseudo-color images of two channels are displayed on the screen of PC in real time. Simultaneously all parameters of flight and radiometric data are stored in hard disk for postprocessing. The sensitivity of the radiometers of flight and radiometric data are stored in hard disk for postprocessing. The sensitivity of the radiometers (Delta) T equals 0.16K. A new display method, unequal size element arc displaying method, is used in image displaying. Several experiments on mobile tower were carried out and the images demonstrate the AMRI is available to work steadily and accurately.

  3. High-Spatial- and High-Spectral-Resolution Observations of the Inhomogeneous Outer Atmosphere of the M Giant BK Vir

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.

    2011-09-01

    We present high-spatial- and high-spectral-resolution observations of the normal M-type AGB star BK Vir using the AMBER instrument at the Very Large Telescope Interferometer. AMBER's high spatial resolution (9.5 mas) and high spectral resolution (λ/Δλ = 12000) enable us to probe the inhomogeneous structure of the atmosphere using the CO first-overtone lines near 2.3μm. The AMBER data in the CO lines reveal the presence of inhomogeneous CO layers, which are much more extended than predicted by hydrostatic photospheric models. These AMBER observations are the first to spatially resolve the “warm molecular envelope” toward AGB stars in individual CO lines.

  4. TEMPORAL AND SPATIAL ANALYSES OF SPECTRAL INDICES OF NONTHERMAL EMISSIONS DERIVED FROM HARD X-RAYS AND MICROWAVES

    SciTech Connect

    Asai, Ayumi; Kiyohara, Junko; Takasaki, Hiroyuki; Narukage, Noriyuki; Yokoyama, Takaaki; Masuda, Satoshi; Shimojo, Masumi; Nakajima, Hiroshi

    2013-02-15

    We studied electron spectral indices of nonthermal emissions seen in hard X-rays (HXRs) and microwaves. We analyzed 12 flares observed by the Hard X-Ray Telescope aboard Yohkoh, Nobeyama Radio Polarimeters, and the Nobeyama Radioheliograph (NoRH), and compared the spectral indices derived from total fluxes of HXRs and microwaves. Except for four events, which have very soft HXR spectra suffering from the thermal component, these flares show a gap {Delta}{delta} between the electron spectral indices derived from HXRs {delta} {sub X} and those from microwaves {delta}{sub {mu}} ({Delta}{delta} = {delta} {sub X} - {delta}{sub {mu}}) of about 1.6. Furthermore, from the start to the peak times of the HXR bursts, the time profiles of the HXR spectral index {delta} {sub X} evolve synchronously with those of the microwave spectral index {delta}{sub {mu}}, keeping the constant gap. We also examined the spatially resolved distribution of the microwave spectral index by using NoRH data. The microwave spectral index {delta}{sub {mu}} tends to be larger, which means a softer spectrum, at HXR footpoint sources with stronger magnetic field than that at the loop tops. These results suggest that the electron spectra are bent at around several hundreds of keV, and become harder at the higher energy range that contributes the microwave gyrosynchrotron emission.

  5. Spectral-spatial fusion model for robust blood pulse waveform extraction in photoplethysmographic imaging

    PubMed Central

    Amelard, Robert; Clausi, David A.; Wong, Alexander

    2016-01-01

    Photoplethysmographic imaging is an optical solution for non-contact cardiovascular monitoring from a distance. This camera-based technology enables physiological monitoring in situations where contact-based devices may be problematic or infeasible, such as ambulatory, sleep, and multi-individual monitoring. However, automatically extracting the blood pulse waveform signal is challenging due to the unknown mixture of relevant (pulsatile) and irrelevant pixels in the scene. Here, we propose a signal fusion framework, FusionPPG, for extracting a blood pulse waveform signal with strong temporal fidelity from a scene without requiring anatomical priors. The extraction problem is posed as a Bayesian least squares fusion problem, and solved using a novel probabilistic pulsatility model that incorporates both physiologically derived spectral and spatial waveform priors to identify pulsatility characteristics in the scene. Evaluation was performed on a 24-participant sample with various ages (9–60 years) and body compositions (fat% 30.0 ± 7.9, muscle% 40.4 ± 5.3, BMI 25.5 ± 5.2 kg·m−2). Experimental results show stronger matching to the ground-truth blood pulse waveform signal compared to the FaceMeanPPG (p < 0.001) and DistancePPG (p < 0.001) methods. Heart rates predicted using FusionPPG correlated strongly with ground truth measurements (r2 = 0.9952). A cardiac arrhythmia was visually identified in FusionPPG’s waveform via temporal analysis. PMID:28018712

  6. System for processing of airborne images of forest ecosystems using high spectral and spatial resolution data

    NASA Astrophysics Data System (ADS)

    Kozoderov, V. V.; Dmitriev, E. V.; Kamentsev, V. P.

    2014-12-01

    The developed hardware and software system for the recognition of natural and man-made objects based on the airborne hyperspectral sensing implements flight tasks on selected survey routes and computational procedures for solving applied problems that occur in data processing. The basics of object recognition based on obtained images of high spectral and spatial resolution in mathematical terms of sets of sites and labels and the basics of interrelations between separate resolution elements (pixels) for selected object classes are presented. Features of energy minimization of the processed scene are depicted as a target function of the optimization of computation and regularization of the solution of the considered problems as a theoretical basis for distinguishing between classes of objects in the presence of boundaries between them. Examples of the formation of information layers of recorded spectra for selected "pure species" of pine and birch forests are cited, with the separation of illuminated and shaded pixels, which increases the accuracy of object recognition in the processing of the images.

  7. Parallel Implementation of Morphological Profile Based Spectral-Spatial Classification Scheme for Hyperspectral Imagery

    NASA Astrophysics Data System (ADS)

    Kumar, B.; Dikshit, O.

    2016-06-01

    Extended morphological profile (EMP) is a good technique for extracting spectral-spatial information from the images but large size of hyperspectral images is an important concern for creating EMPs. However, with the availability of modern multi-core processors and commodity parallel processing systems like graphics processing units (GPUs) at desktop level, parallel computing provides a viable option to significantly accelerate execution of such computations. In this paper, parallel implementation of an EMP based spectralspatial classification method for hyperspectral imagery is presented. The parallel implementation is done both on multi-core CPU and GPU. The impact of parallelization on speed up and classification accuracy is analyzed. For GPU, the implementation is done in compute unified device architecture (CUDA) C. The experiments are carried out on two well-known hyperspectral images. It is observed from the experimental results that GPU implementation provides a speed up of about 7 times, while parallel implementation on multi-core CPU resulted in speed up of about 3 times. It is also observed that parallel implementation has no adverse impact on the classification accuracy.

  8. Spectral-spatial fusion model for robust blood pulse waveform extraction in photoplethysmographic imaging.

    PubMed

    Amelard, Robert; Clausi, David A; Wong, Alexander

    2016-12-01

    Photoplethysmographic imaging is an optical solution for non-contact cardiovascular monitoring from a distance. This camera-based technology enables physiological monitoring in situations where contact-based devices may be problematic or infeasible, such as ambulatory, sleep, and multi-individual monitoring. However, automatically extracting the blood pulse waveform signal is challenging due to the unknown mixture of relevant (pulsatile) and irrelevant pixels in the scene. Here, we propose a signal fusion framework, FusionPPG, for extracting a blood pulse waveform signal with strong temporal fidelity from a scene without requiring anatomical priors. The extraction problem is posed as a Bayesian least squares fusion problem, and solved using a novel probabilistic pulsatility model that incorporates both physiologically derived spectral and spatial waveform priors to identify pulsatility characteristics in the scene. Evaluation was performed on a 24-participant sample with various ages (9-60 years) and body compositions (fat% 30.0 ± 7.9, muscle% 40.4 ± 5.3, BMI 25.5 ± 5.2 kg·m(-2)). Experimental results show stronger matching to the ground-truth blood pulse waveform signal compared to the FaceMeanPPG (p < 0.001) and DistancePPG (p < 0.001) methods. Heart rates predicted using FusionPPG correlated strongly with ground truth measurements (r(2) = 0.9952). A cardiac arrhythmia was visually identified in FusionPPG's waveform via temporal analysis.

  9. Spatial/Spectral Identification of Endmembers from AVIRIS Data using Mathematical Morphology

    NASA Technical Reports Server (NTRS)

    Plaza, Antonio; Martinez, Pablo; Gualtieri, J. Anthony; Perez, Rosa M.

    2001-01-01

    During the last several years, a number of airborne and satellite hyperspectral sensors have been developed or improved for remote sensing applications. Imaging spectrometry allows the detection of materials, objects and regions in a particular scene with a high degree of accuracy. Hyperspectral data typically consist of hundreds of thousands of spectra, so the analysis of this information is a key issue. Mathematical morphology theory is a widely used nonlinear technique for image analysis and pattern recognition. Although it is especially well suited to segment binary or grayscale images with irregular and complex shapes, its application in the classification/segmentation of multispectral or hyperspectral images has been quite rare. In this paper, we discuss a new completely automated methodology to find endmembers in the hyperspectral data cube using mathematical morphology. The extension of classic morphology to the hyperspectral domain allows us to integrate spectral and spatial information in the analysis process. In Section 3, some basic concepts about mathematical morphology and the technical details of our algorithm are provided. In Section 4, the accuracy of the proposed method is tested by its application to real hyperspectral data obtained from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imaging spectrometer. Some details about these data and reference results, obtained by well-known endmember extraction techniques, are provided in Section 2. Finally, in Section 5 we expose the main conclusions at which we have arrived.

  10. Spatial/Spectral Identification of Endmembers from AVIRIS Data using Mathematical Morphology

    NASA Technical Reports Server (NTRS)

    Plaza, Antonio; Martinez, Pablo; Gualtieri, J. Anthony; Perez, Rosa M.

    2001-01-01

    During the last several years, a number of airborne and satellite hyperspectral sensors have been developed or improved for remote sensing applications. Imaging spectrometry allows the detection of materials, objects and regions in a particular scene with a high degree of accuracy. Hyperspectral data typically consist of hundreds of thousands of spectra, so the analysis of this information is a key issue. Mathematical morphology theory is a widely used nonlinear technique for image analysis and pattern recognition. Although it is especially well suited to segment binary or grayscale images with irregular and complex shapes, its application in the classification/segmentation of multispectral or hyperspectral images has been quite rare. In this paper, we discuss a new completely automated methodology to find endmembers in the hyperspectral data cube using mathematical morphology. The extension of classic morphology to the hyperspectral domain allows us to integrate spectral and spatial information in the analysis process. In Section 3, some basic concepts about mathematical morphology and the technical details of our algorithm are provided. In Section 4, the accuracy of the proposed method is tested by its application to real hyperspectral data obtained from the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imaging spectrometer. Some details about these data and reference results, obtained by well-known endmember extraction techniques, are provided in Section 2. Finally, in Section 5 we expose the main conclusions at which we have arrived.

  11. Capability of existing spectral indices to map biocrusts in a spatially heterogeneous semiarid areas

    NASA Astrophysics Data System (ADS)

    Alonso, Marta; Rodriguez-Caballero, Emilio; Escribano, Paula; Chamizo, Sonia; Luna, Lourdes; Cantón, Yolanda

    2014-05-01

    Dryland ecosystems cover about 40 % of the land surface and play a major role in global biophysical processes. These systems usually show sparse vegetation cover interspersed over a bare open matrix, often covered by complex communities of cyanobacteria, algae, fungi, lichens and bryophytes, so called biological soil crusts (BSCs). These microorganisms control gas, water and nutrient exchange into and through soils and affect essential ecosystem processes, including soil respiration, carbon and nitrogen fixation, establishment and performance of vascular plants, soil erodibility, evaporation, water retention and water infiltration. Given the importance of BSCs in ecosystem functioning, accurate and spatially explicit information on the distribution of BSCs is mandatory. With this objective, considerable effort has been devoted in the last decades to identify and map BSCs using remote sensing data, and some spectral indices have been developed for BSC mapping: the crust index (CI), the biological soil crust index (BSCI), the continuum removal crust identification algorithm (CRCIA) and the methodology proposed by Chamizo et al. (2012), hereafter Crust Development Index (CDI). Despite many of these indices have demonstrated their usefulness to map BSCs in the areas where they have been developed, their applicability for mapping BSCs in other areas, with different BSC composition, has not been tested. In this study, we test the feasibility of the 4 previous indices published in the literature (CI, BSCI, CRCIA and CDI) for mapping different types of BSC in a topography complex area (a badlands system in SE Spain) covered by sparse vegetation embedded in a heterogeneous bare matrix dominated by two main types of BSC, lichen and cyanobacteria. We calibrated all indices for both, lichen and cyanobacteria separately, previous to their application to a hyperespectral image of the area. Moreover, we applied a support vector machine classification (SVM) to test its accuracy as

  12. A Radiometric Uncertainty Tool for OLCI

    NASA Astrophysics Data System (ADS)

    Hunt, S.; Nieke, J.

    2016-08-01

    With its first satellite launched in February 2016, the Sentinel-3 mission will support Ocean, Land, Atmospheric, Emergency, Security and Cryospheric applications and related Copernicus services (http://www.copernicus.eu). One of the key payloads carried by the satellite, OLCI (Ocean and Land Colour Instrument), is a push-broom imaging spectrometer designed to image the Earth's surface in 21 spectral bands, from the visible to the near infrared, across a 1200 km swath. An understanding of the quality of the Level 1b (L1) data produced by OLCI is important for many of its applications. As such, work has been ongoing to develop a software tool to determine the per pixel uncertainty of these images to be used by L1 product users. This tool has been named OLCI-RUT (OLCI - Radiometric Uncertainty Tool) and this report provides a description of its development.

  13. JACIE Radiometric Assessment of QuickBird Multispectral Imagery

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Carver, David; Holekamp, Kara; Knowlton, Kelly; Ryan, Robert; Zanoni, Vicki; Thome, Kurtis; Aaron, David

    2004-01-01

    Radiometric calibration of commercial imaging satellite products is required to ensure that science and application communities can place confidence in the imagery they use and can fully understand its properties. Inaccurate radiometric calibrations can lead to erroneous decisions and invalid conclusions and can limit intercomparisons with other systems. To address this calibration need, the NASA Stennis Space Center (SSC) Earth Science Applications (ESA) directorate,through the Joint Agency for Commercial Imagery Evaluation (JACIE) framework, established a commercial imaging satellite radiometric calibration team consisting of two groups: 1) NASA SSC ESA, supported by South Dakota State University, and 2) the University of Arizona Remote Sensing Group. The two groups determined the absolute radiometric calibration coefficients of the Digital Globe 4-band, 2.4-m QuickBird multispectral product covering the visible through near-infrared spectral region. For a 2-year period beginning in 2002, both groups employed some variant of a reflectance-based vicarious calibration approach, which required ground-based measurements coincident with QuickBird image acquisitions and radiative transfer calculations. The groups chose several study sites throughout the United States that covered nearly the entire dynamic range of the QuickBird sensor. QuickBird at-sensor radiance values were compared with those estimated by the two independent groups to determine the QuickBird sensor's radiometric accuracy. Approximately 20 at-sensor radiance estimates were vicariously determined each year. The estimates were combined to provide a high-precision radiometric gain calibration coefficient. The results of this evaluation provide the user community with an independent assessment of the QuickBird sensor's absolute calibration and stability over the 2-year period. While the techniques and method described reflect those developed at the NASA SSC, the results of both JACIE team groups are

  14. Development of a practical spatial-spectral analysis protocol for breast histopathology using Fourier transform infrared spectroscopic imaging.

    PubMed

    Pounder, F Nell; Reddy, Rohith K; Bhargava, Rohit

    2016-06-23

    Breast cancer screening provides sensitive tumor identification, but low specificity implies that a vast majority of biopsies are not ultimately diagnosed as cancer. Automated techniques to evaluate biopsies can prevent errors, reduce pathologist workload and provide objective analysis. Fourier transform infrared (FT-IR) spectroscopic imaging provides both molecular signatures and spatial information that may be applicable for pathology. Here, we utilize both the spectral and spatial information to develop a combined classifier that provides rapid tissue assessment. First, we evaluated the potential of IR imaging to provide a diagnosis using spectral data alone. While highly accurate histologic [epithelium, stroma] recognition could be achieved, the same was not possible for disease [cancer, no-cancer] due to the diversity of spectral signals. Hence, we employed spatial data, developing and evaluating increasingly complex models, to detect cancers. Sub-mm tumors could be very confidently predicted as indicated by the quantitative measurement of accuracy via receiver operating characteristic (ROC) curve analyses. The developed protocol was validated with a small set and statistical performance used to develop a model that predicts study design for a large scale, definitive validation. The results of evaluation on different instruments, at higher noise levels, under a coarser spectral resolution and two sampling modes [transmission and transflection], indicate that the protocol is highly accurate under a variety of conditions. The study paves the way to validating IR imaging for rapid breast tumor detection, its statistical validation and potential directions for optimization of the speed and sampling for clinical deployment.

  15. Radiometric Calibration of the Earth Observing System's Imaging Sensors

    NASA Technical Reports Server (NTRS)

    Slater, Philip N. (Principal Investigator)

    1997-01-01

    The work on the grant was mainly directed towards developing new, accurate, redundant methods for the in-flight, absolute radiometric calibration of satellite multispectral imaging systems and refining the accuracy of methods already in use. Initially the work was in preparation for the calibration of MODIS and HIRIS (before the development of that sensor was canceled), with the realization it would be applicable to most imaging multi- or hyper-spectral sensors provided their spatial or spectral resolutions were not too coarse. The work on the grant involved three different ground-based, in-flight calibration methods reflectance-based radiance-based and diffuse-to-global irradiance ratio used with the reflectance-based method. This continuing research had the dual advantage of: (1) developing several independent methods to create the redundancy that is essential for the identification and hopefully the elimination of systematic errors; and (2) refining the measurement techniques and algorithms that can be used not only for improving calibration accuracy but also for the reverse process of retrieving ground reflectances from calibrated remote-sensing data. The grant also provided the support necessary for us to embark on other projects such as the ratioing radiometer approach to on-board calibration (this has been further developed by SBRS as the 'solar diffuser stability monitor' and is incorporated into the most important on-board calibration system for MODIS)- another example of the work, which was a spin-off from the grant funding, was a study of solar diffuser materials. Journal citations, titles and abstracts of publications authored by faculty, staff, and students are also attached.

  16. Spatial resolution enhancement of hyperspectral image based on the combination of spectral mixing model and observation model

    NASA Astrophysics Data System (ADS)

    Zhang, Yifan

    2014-10-01

    To improve the spatial resolution of a hyperspectral (HS) observation of a scene with the aid of an auxiliary multispectral (MS) observation, a new spectral unmixing-based HS and MS image fusion approach is presented in this paper. In the proposed fusion approach, linear spectral unmixing with sparsity constraint is employed, by taking the impact of linear observation model on linear mixing model into consideration. Simulative experiment is employed for verification and comparison. It is illustrated that the proposed approach would be more promising for practical utilization compared to some state-of-the-art approaches, due to its good balance between fusion performance and calculation cost.

  17. LANDSAT-4 multispectral scanner (MSS) subsystem radiometric characterization

    NASA Technical Reports Server (NTRS)

    Alford, W. (Editor); Barker, J. (Editor); Clark, B. P.; Dasgupta, R.

    1983-01-01

    The multispectral band scanner (mass) and its spectral characteristics are described and methods are given for relating video digital levels on computer compatible tapes to radiance into the sensor. Topics covered include prelaunch calibration procedures and postlaunch radiometric processng. Examples of current data resident on the MSS image processing system are included. The MSS on LANDSAT 4 is compared with the scanners on earlier LANDSAT satellites.

  18. Nonlinear Spatial-Temporal Spectral Analyses for Diagnosing Solar 11-Year Signal in the Northern Hemisphere Atmosphere

    NASA Astrophysics Data System (ADS)

    Powell, A. M.; Chen, M.

    2005-12-01

    The major dilemma in the search for a Sun-Earth connection is tiny solar output variations appear insignificant relative to dynamic atmospheric changes while many synoptic and climatic parameters are found to be significantly correlated with the solar variation at different time scales. Based on previous analysis, the solar variations are assumed to exert their influence through nonlinear modulation of the existing dynamic or thermodynamic processes. Nonlinear spatial-temporal spectral analysis is helpful for identifying nonlinear solar signals in the atmospheric observations and establishing nonlinear feedback mechanisms. Using the 50-year NCEP/NCAR reanalysis data, an extensive spatial-temp spectral analysis is performed. Fourier transformation is first applied latitude by latitude to get zonal waves of different spatial scales. The time series of the amplitude (energy) of each wave is filtered to isolate different time-scale waves. From the viewpoint of linear wave theory, these waves are assumed to carry atmospheric energy derived from the original sources and the atmospheric response to the source functions. The temporal change of wave amplitude is closely related to the source energy change, such as boundary condition change, or nonlinear adjustment of background state (energy exchange from different scales), etc. The relevant spatial-temp spectral structure change associated with solar variations will be addressed in this study. The results suggest nonlinear atmospheric processes may couple solar variation with atmospheric variations.

  19. Effects of simulated spectral holes on speech intelligibility and spatial release from masking under binaural and monaural listening

    PubMed Central

    Garadat, Soha N.; Litovsky, Ruth Y.; Yu, Gongqiang; Zeng, Fan-Gang

    2010-01-01

    The possibility that “dead regions” or “spectral holes” can account for some differences in performance between bilateral cochlear implant (CI) users and normal-hearing listeners was explored. Using a 20-band noise-excited vocoder to simulate CI processing, this study examined effects of spectral holes on speech reception thresholds (SRTs) and spatial release from masking (SRM) in difficult listening conditions. Prior to processing, stimuli were convolved through head-related transfer-functions to provide listeners with free-field directional cues. Processed stimuli were presented over headphones under binaural or monaural (right ear) conditions. Using Greenwood’s [(1990). J. Acoust. Soc. Am. 87, 2592–2605] frequency-position function and assuming a cochlear length of 35 mm, spectral holes were created for variable sizes (6 and 10 mm) and locations (base, middle, and apex). Results show that middle-frequency spectral holes were the most disruptive to SRTs, whereas high-frequency spectral holes were the most disruptive to SRM. Spectral holes generally reduced binaural advantages in difficult listening conditions. These results suggest the importance of measuring dead regions in CI users. It is possible that customized programming for bilateral CI processors based on knowledge about dead regions can enhance performance in adverse listening situations. PMID:20136220

  20. Effects of simulated spectral holes on speech intelligibility and spatial release from masking under binaural and monaural listening.

    PubMed

    Garadat, Soha N; Litovsky, Ruth Y; Yu, Gongqiang; Zeng, Fan-Gang

    2010-02-01

    The possibility that "dead regions" or "spectral holes" can account for some differences in performance between bilateral cochlear implant (CI) users and normal-hearing listeners was explored. Using a 20-band noise-excited vocoder to simulate CI processing, this study examined effects of spectral holes on speech reception thresholds (SRTs) and spatial release from masking (SRM) in difficult listening conditions. Prior to processing, stimuli were convolved through head-related transfer-functions to provide listeners with free-field directional cues. Processed stimuli were presented over headphones under binaural or monaural (right ear) conditions. Using Greenwood's [(1990). J. Acoust. Soc. Am. 87, 2592-2605] frequency-position function and assuming a cochlear length of 35 mm, spectral holes were created for variable sizes (6 and 10 mm) and locations (base, middle, and apex). Results show that middle-frequency spectral holes were the most disruptive to SRTs, whereas high-frequency spectral holes were the most disruptive to SRM. Spectral holes generally reduced binaural advantages in difficult listening conditions. These results suggest the importance of measuring dead regions in CI users. It is possible that customized programming for bilateral CI processors based on knowledge about dead regions can enhance performance in adverse listening situations.

  1. Spatially-dense, multi-spectral, frequency-domain diffuse optical tomography of breast cancer

    NASA Astrophysics Data System (ADS)

    Ban, Han Yong

    Diffuse optical tomography (DOT) employs near-infrared light to image the concentration of chromophores and cell organelles in tissue and thereby providing access to functional parameters that can differentiate cancerous from normal tissues. This thesis describes research at the bench and in the clinic that explores and identifies the potential of DOT breast cancer imaging. The bench and clinic instrumentation differ but share important features: they utilize a very large, spatially dense, set of source-detector pairs (10 7) for imaging in the parallel-plate geometry. The bench experiments explored three-dimensional (3D) image resolution and fidelity as a function of numerous parameters and also ascertained the effects of a chest wall phantom. The chest wall is always present but is typically ignored in breast DOT. My experiments clarified chest wall influences and developed schemes to mitigate these effects. Mostly, these schemes involved selective data exclusion, but their efficacy also depended on reconstruction approach. Reconstruction algorithms based on analytic (fast) Fourier inversion and linear algebraic techniques were explored. The clinical experiments centered around a DOT instrument that I designed, constructed, and have begun to test (in-vitro and in-vivo). This instrumentation offers many features new to the field. Specifically, the imager employs spatially-dense, multi-spectral, frequency-domain data; it possesses the world's largest optical source-detector density yet reported, facilitated by highly-parallel CCD-based frequency-domain imaging based on gain-modulation heterodyne detection. The instrument thus measures both phase and amplitude of the diffusive light waves. Other features include both frontal and sagittal breast imaging capabilities, ancillary cameras for measurement of breast boundary profiles, real-time data normalization, and mechanical improvements for patient comfort. The instrument design and construction is my most significant

  2. A Non-Radiative Transfer Approach to Radiometric Vicarious Calibration

    NASA Technical Reports Server (NTRS)

    Ryan, Robert; Holekamp, Kara; Pagnutti, Mary; Stanley, Thomas

    2007-01-01

    TOA (top-of-atmosphere) radiance from high-spatial-resolution satellite imagery systems is important for a wide variety of research and applications. Many research initiatives require data with absolute radiometric accuracy better than a few percent. The conversion of satellite digital numbers to radiance depends on accurate radiometric calibration. A common method for determining and validating radiometric calibrations is to rely upon vicarious calibration approaches. Historically, vicarious calibration methods use radiative transfer codes with ground-based atmosphere and surface reflectance or radiance inputs for estimating TOA radiance values. These TOA radiance values are compared against the satellite digital numbers to determine the radiometric calibration. However, the radiative transfer codes used depend on many assumptions about the aerosol properties and the atmospheric point spread function. A measurement-based atmospheric radiance estimation approach for high-spatial-resolution, multispectral, visible/near-infrared sensors is presented that eliminates the use of radiative transfer codes and many of the underlying assumptions. A comparison between the radiative transfer and non-radiative transfer approaches is made.

  3. Reduced field-of-view excitation using second-order gradients and spatial-spectral radiofrequency pulses.

    PubMed

    Ma, Chao; Xu, Dan; King, Kevin F; Liang, Zhi-Pei

    2013-02-01

    The performance of multidimensional spatially selective radiofrequency (RF) pulses is often limited by their long duration. In this article, high-order, nonlinear gradients are exploited to reduce multidimensional RF pulse length. Specifically, by leveraging the multidimensional spatial dependence of second-order gradients, a two-dimensional spatial-spectral RF pulse is designed to achieve three-dimensional spatial selectivity, i.e., to excite a circular region-of-interest in a thin slice for reduced field-of-view imaging. Compared to conventional methods that use three-dimensional RF pulses and linear gradients, the proposed method requires only two-dimensional RF pulses, and thus can significantly shorten the RF pulses and/or improve excitation accuracy. The proposed method has been validated through Bloch equation simulations and phantom experiments on a commercial 3.0T MRI scanner.

  4. Relationships Among Peripheral and Central Electrophysiological Measures of Spatial and Spectral Selectivity and Speech Perception in Cochlear Implant Users

    PubMed Central

    Scheperle, Rachel A.; Abbas, Paul J.

    2014-01-01

    Objectives The ability to perceive speech is related to the listener’s ability to differentiate among frequencies (i.e., spectral resolution). Cochlear implant (CI) users exhibit variable speech-perception and spectral-resolution abilities, which can be attributed in part to the extent of electrode interactions at the periphery (i.e., spatial selectivity). However, electrophysiological measures of peripheral spatial selectivity have not been found to correlate with speech perception. The purpose of this study was to evaluate auditory processing at the periphery and cortex using both simple and spectrally complex stimuli to better understand the stages of neural processing underlying speech perception. The hypotheses were that (1) by more completely characterizing peripheral excitation patterns than in previous studies, significant correlations with measures of spectral selectivity and speech perception would be observed, (2) adding information about processing at a level central to the auditory nerve would account for additional variability in speech perception, and (3) responses elicited with spectrally complex stimuli would be more strongly correlated with speech perception than responses elicited with spectrally simple stimuli. Design Eleven adult CI users participated. Three experimental processor programs (MAPs) were created to vary the likelihood of electrode interactions within each participant. For each MAP, a subset of 7 of 22 intracochlear electrodes was activated: adjacent (MAP 1), every-other (MAP 2), or every third (MAP 3). Peripheral spatial selectivity was assessed using the electrically evoked compound action potential (ECAP) to obtain channel-interaction functions for all activated electrodes (13 functions total). Central processing was assessed by eliciting the auditory change complex (ACC) with both spatial (electrode pairs) and spectral (rippled noise) stimulus changes. Speech-perception measures included vowel-discrimination and the Bamford

  5. Spatial and spectral image distortions caused by diffraction of an ordinary polarised light beam by an ultrasonic wave

    SciTech Connect

    Machikhin, A S; Pozhar, V E

    2015-02-28

    We consider the problem of determining the spatial and spectral image distortions arising from anisotropic diffraction by ultrasonic waves in crystals with ordinary polarised light (o → e). By neglecting the small-birefringence approximation, we obtain analytical solutions that describe the dependence of the diffraction angles and wave mismatch on the acousto-optic (AO) interaction geometry and crystal parameters. The formulas derived allow one to calculate and analyse the magnitude of diffraction-induced spatial and spectral image distortions and to identify the main types of distortions: chromatic compression and trapezoidal deformation. A comparison of the values of these distortions in the diffraction of ordinary and extraordinary polarised light shows that they are almost equal in magnitude and opposite in signs, so that consistent diffraction (o → e → o or e → o → e) in two identical AO cells rotated through 180° in the plane of diffraction can compensate for these distortions. (diffraction of radiation)

  6. Method of synchronization measurement via spatial-spectral interference in coherent combination of multi-channel ultra-short pulses

    NASA Astrophysics Data System (ADS)

    Li, Z. L.; Zuo, Y. L.; Wu, Z. H.; Wang, X.; Mu, J.; Yu, H. Y.; Zhao, D.; Zhu, Q. H.; Su, J. Q.; Zhou, K. N.; Zhou, S.; Feng, X.; Zhang, S.; Liu, H. Z.

    2017-08-01

    Spatial-spectral interference fringes contain information on the time delay between pulses. By extracting the slope of the equiphase line in the spatial-spectral interference fringes, a large range and high-precision detection of the time delay is realized. Theoretical analysis is given. An experiment demonstrates the fundamental process for obtaining the time delay between two femtosecond pulses. In the current experiment the measurement range is from 0.4 fs to hundreds of fs. This method was first proposed for synchronization measurement of coherent combination of ultra-short pulses in a multi-channel system. The method can be applied at large scales in an ultra-short pulse laser facility.

  7. Spatially and spectrally resolved ultra-narrowband TE-polarization absorber based on the guide-mode resonance

    NASA Astrophysics Data System (ADS)

    Liao, Yan-Lin; Zhao, Yan; Zhang, Xingfang; Zhang, Wen; Wang, Zhongzhu

    2017-08-01

    A spatially and spectrally resolved ultra-narrowband absorber with a dielectric grating and metal substrate has been reported. The absorber shows that the absorption rate is more than 0.99 with the absorption bandwidth less than 1.5 nm at normal incidence for TE polarization (electric field is parallel to grating grooves). The angular width of the absorption is about 0.27∘. The wavelength-angle sensitivity and absorption-angle sensitivity are 13.4 nm per degree and 296.3% per degree, respectively. The simulation results also show the spatially and spectrally resolved ultra-narrowband absorption is originated from the guide-mode resonance. In addition, the wavelength-angle sensitivity can be improved by enlarging the grating period according to the guide-mode resonance mechanism. The proposed absorber has potential applications in optical filters, angle measurement and thermal emitters.

  8. Super-Spatial- and -Spectral-Resolution in Vibrational Imaging via Saturated Coherent Anti-Stokes Raman Scattering

    NASA Astrophysics Data System (ADS)

    Yonemaru, Yasuo; Palonpon, Almar F.; Kawano, Shogo; Smith, Nicholas I.; Kawata, Satoshi; Fujita, Katsumasa

    2015-07-01

    We demonstrate a vibrational microscopy technique with subdiffraction spatial resolution by the use of saturation of coherent anti-Stokes Raman scattering (CARS). The saturated CARS signals effectively produce a reduced point-spread function at harmonic frequencies, which is extracted by temporal modulation of the pump beam and demodulation of the CARS signal. An increase in spectral resolution and suppression of the nonresonant background signal accompany the spatial- resolution enhancement. Our simple, enhanced CARS technique promises to be useful in studying molecules in gas and liquid phases as well as soft condensed-matter systems.

  9. The Landsat Data Continuity Mission Operational Land Imager: Radiometric Performance

    NASA Technical Reports Server (NTRS)

    Markham, Brian; Dabney, Philip; Pedelty, Jeffrey

    2011-01-01

    The Operational Land Imager (OLI) is one of two instruments to fly on the Landsat Data Continuity Mission (LDCM), which is scheduled to launch in December 2012 to become the 8th in the series of Landsat satellites. The OLI images in the solar reflective part of the spectrum, with bands similar to bands 1-5, 7 and the panchromatic band on the Landsat-7 ETM+ instrument. In addition, it has a 20 nm bandpass spectral band at 443 nm for coastal and aerosol studies and a 30 nm band at 1375 nm to aid in cirrus cloud detection. Like ETM+, spatial resolution is 30 m in the all but the panchromatic band, which is 15 meters. OLI is a pushbroom radiometer with approximately 6000 detectors per 30 meter band as opposed to the 16 detectors per band on the whiskbroom ETM+. Data are quantized to 12 bits on OLI as opposed to 8 bits on ETM+ to take advantage of the improved signal to noise ratio provided by the pushbroom design. The saturation radiances are higher on OLI than ETM+ to effectively eliminate saturation issues over bright Earth targets. OLI includes dual solar diffusers for on-orbit absolute and relative (detector to detector) radiometric calibration. Additionally, OLI has 3 sets of on-board lamps that illuminate the OLI focal plane through the full optical system, providing additional checks on the OLI's response[l]. OLI has been designed and built by Ball Aerospace & Technology Corp. (BATC) and is currently undergoing testing and calibration in preparation for delivery in Spring 2011. Final pre-launch performance results should be available in time for presentation at the conference. Preliminary results will be presented below. These results are based on the performance of the Engineering Development Unit (EDU) that was radiometrically tested at the integrated instrument level in 2010 and assembly level measurements made on the flight unit. Signal-to-Noise (SNR) performance: One of the advantages of a pushbroom system is the increased dwell time of the detectors

  10. Calibration of a helium-cooled infrared spatial radiometer and grating spectrometer

    NASA Technical Reports Server (NTRS)

    Jacobsen, Larry; Sargent, Steve; Wyatt, Clair L.; Steed, Allan J.

    1992-01-01

    Methods used by the Space Dynamics Laboratory of Utah State University (SDL/USU) to calibrate infrared sensors are described, using the Infrared Background Signature Survey (IBSS) spatial radiometer and grating spectrometer as examples. A calibration equation and a radiometric model are given for each sensor to describe their responsivity in terms of individual radiometric parameters. The calibration equation terms include dark offset, linearity, absolute responsivity, and measurement uncertainty, and the radiometric model domains include spatial, spectral, and temporal domains. A portable calibration facility, designed and fabricated by SDL/USU, provided collimated, extended, diffuse scatter, and Jones sources in a single cryogenic dewar. This multi-function calibrator allowed calibration personnel to complete a full calibration of the IBSS infrared radiometer and spectrometer in two 15-day periods. A calibration data system was developed to control and monitor the calibration facility, and to record and analyze sensor data.

  11. Site characterization for calibration of radiometric sensors using vicarious method

    NASA Astrophysics Data System (ADS)

    Parihar, Shailesh; Rathore, L. S.; Mohapatra, M.; Sharma, A. K.; Mitra, A. K.; Bhatla, R.; Singh, R. S.; Desai, Yogdeep; Srivastava, Shailendra S.

    2016-05-01

    Radiometric performances of earth observation satellite/sensors vary from ground pre-launch calibration campaign to post launch period extended to lifetime of the satellite due to launching vibrations. Therefore calibration is carried out worldwide through various methods throughout satellite lifetime. In India Indian Space Research Organization (ISRO) calibrates the sensor of Resourcesat-2 satellite by vicarious method. One of these vicarious calibration methods is the reflectance-based approach that is applied in this study for radiometric calibration of sensors on-board Resouresat-2 satellite. The results of ground-based measurement of atmospheric conditions and surface reflectance are made at Bap, Rajasthan Calibration/Validation (Cal/Val) site. Cal/Val observations at site were carried out with hyper-spectral Spectroradiometer covering spectral range of 350nm- 2500nm for radiometric characterization of the site. The Sunphotometer/Ozonometer for measuring the atmospheric parameters has also been used. The calibrated radiance is converted to absolute at-sensor spectral reflectance and Top-Of-Atmosphere (TOA) radiance. TOA radiance was computed using radiative transfer model `Second simulation of the satellite signal in the solar spectrum' (6S), which can accurately simulate the problems introduced by the presence of the atmosphere along the path from Sun to target (surface) to Sensor. The methodology for band averaged reflectance retrieval and spectral reflectance fitting process are described. Then the spectral reflectance and atmospheric parameters are put into 6S code to predict TOA radiance which compare with Resourcesat-2 radiance. Spectral signature and its reflectance ratio indicate the uniformity of the site. Thus the study proves that the selected site is suitable for vicarious calibration of sensor of Resourcesat-2. Further the study demonstrates the procedure for similar exercise for site selection for Cal/Val analysis of other satellite over India

  12. Analytic model for the spatial and spectral resolution of pixellated semiconducting detectors of high-energy photons

    SciTech Connect

    Kozorezov, A.G.; Wigmore, J.K.; Owens, A.; Hartog, R. den; Peacock, A.

    2005-04-01

    We report the development of a general analytic method for describing the responsivity and resolution for a pixellated semiconductor detector structure in terms of device and material properties. The method allows both drift and diffusive transport to be modelled, for which previously only Monte Carlo techniques have been available. We obtain a general solution, and show specific results for an array of square pixels, illustrating the device constraints required to optimize spatial and spectral resolution.

  13. Development of new two-dimensional spectral/spatial code based on dynamic cyclic shift code for OCDMA system

    NASA Astrophysics Data System (ADS)

    Jellali, Nabiha; Najjar, Monia; Ferchichi, Moez; Rezig, Houria

    2017-07-01

    In this paper, a new two-dimensional spectral/spatial codes family, named two dimensional dynamic cyclic shift codes (2D-DCS) is introduced. The 2D-DCS codes are derived from the dynamic cyclic shift code for the spectral and spatial coding. The proposed system can fully eliminate the multiple access interference (MAI) by using the MAI cancellation property. The effect of shot noise, phase-induced intensity noise and thermal noise are used to analyze the code performance. In comparison with existing two dimensional (2D) codes, such as 2D perfect difference (2D-PD), 2D Extended Enhanced Double Weight (2D-Extended-EDW) and 2D hybrid (2D-FCC/MDW) codes, the numerical results show that our proposed codes have the best performance. By keeping the same code length and increasing the spatial code, the performance of our 2D-DCS system is enhanced: it provides higher data rates while using lower transmitted power and a smaller spectral width.

  14. What is the physical limit for the spatial resolution of satellite observations in the UV, vis, and NIR spectral range?

    NASA Astrophysics Data System (ADS)

    Wagner, Thomas

    2017-04-01

    Since 1995 satellite instruments are in orbit, which observe the sun light scattered back from the Earth with moderate spectral resolution. From these observations, global maps of many important atmospheric trace gases can be derived. While the spatial resolution of the first instrument (GOME-1) was rather coarse (320 x 40 km2) it has strongly improved in recent years (e.g. OMI: 13 x 24 km2) and will be improved further in the near future (Sentinel 5P: 3.5 x 7 km2). These improvements were mainly driven by technical development of the satellite instruments and the available data rates for downlinking the measured spectra. Nevertheless, the ultimate limit for the spatial resolution results from requirements on the signal to noise ratio of the measured spectra, which depend on the wavelength range, observatiom geometry and atmospheric composition (e.g. clouds), but also on the size of the detector and the spectral resolution and coverage of the satellite instruments. In this presentation we discuss these dependencies and estimate the best achievable spatial resolution for different species measured in different spectral ranges by UV, vis, NIR satellite instruments.

  15. Spectral signature measurements during the whole life cycle of annual crops and sustainable irrigation management over Cyprus using remote sensing and spectro-radiometric data: the cases of spring potatoes and peas

    NASA Astrophysics Data System (ADS)

    Papadavid, George; Hadjimitsis, Diofantos G.

    2009-09-01

    This research paper focus on how spectral signatures and evapotranspiration (ET) vary during the whole life cycle of specific annual crops cultivated in the area located in Mandria village, in Paphos District area in Cyprus. The spectral signatures of these crops are collected for the whole life cycle in order to examine how ET changes due to morphological changes of the crops. The GER 1500 spectro-radiometer has been used to collect the spectral signatures of the crops for the whole crop season. The spectral signatures of two main crops -potatoes and peas- have been acquired in-situ, from the beginning of March to the end of April 2009. The purpose of this paper is to enlighten irrigation managers how ET fluctuates during the crop season and how irrigation scheduling is related to spectral signature of the crops. The data extracted from this paper will also assist the decision makers on irrigation level to have a general idea how crops need to be irrigated during their whole life cycle. This project has been funded by the Cyprus Research Promotion Foundation and the Regional Development Fund of European Union.

  16. A high-order spatial filter for a cubed-sphere spectral element model

    NASA Astrophysics Data System (ADS)

    Kang, Hyun-Gyu; Cheong, Hyeong-Bin

    2017-04-01

    A high-order spatial filter is developed for the spectral-element-method dynamical core on the cubed-sphere grid which employs the Gauss-Lobatto Lagrange interpolating polynomials (GLLIP) as orthogonal basis functions. The filter equation is the high-order Helmholtz equation which corresponds to the implicit time-differencing of a diffusion equation employing the high-order Laplacian. The Laplacian operator is discretized within a cell which is a building block of the cubed sphere grid and consists of the Gauss-Lobatto grid. When discretizing a high-order Laplacian, due to the requirement of C0 continuity along the cell boundaries the grid-points in neighboring cells should be used for the target cell: The number of neighboring cells is nearly quadratically proportional to the filter order. Discrete Helmholtz equation yields a huge-sized and highly sparse matrix equation whose size is N*N with N the number of total grid points on the globe. The number of nonzero entries is also almost in quadratic proportion to the filter order. Filtering is accomplished by solving the huge-matrix equation. While requiring a significant computing time, the solution of global matrix provides the filtered field free of discontinuity along the cell boundaries. To achieve the computational efficiency and the accuracy at the same time, the solution of the matrix equation was obtained by only accounting for the finite number of adjacent cells. This is called as a local-domain filter. It was shown that to remove the numerical noise near the grid-scale, inclusion of 5*5 cells for the local-domain filter was found sufficient, giving the same accuracy as that obtained by global domain solution while reducing the computing time to a considerably lower level. The high-order filter was evaluated using the standard test cases including the baroclinic instability of the zonal flow. Results indicated that the filter performs better on the removal of grid-scale numerical noises than the explicit

  17. Deep brain stimulation modulates synchrony within spatially and spectrally distinct resting state networks in Parkinson's disease.

    PubMed

    Oswal, Ashwini; Beudel, Martijn; Zrinzo, Ludvic; Limousin, Patricia; Hariz, Marwan; Foltynie, Tom; Litvak, Vladimir; Brown, Peter

    2016-05-01

    Chronic dopamine depletion in Parkinson's disease leads to progressive motor and cognitive impairment, which is associated with the emergence of characteristic patterns of synchronous oscillatory activity within cortico-basal-ganglia circuits. Deep brain stimulation of the subthalamic nucleus is an effective treatment for Parkinson's disease, but its influence on synchronous activity in cortico-basal-ganglia loops remains to be fully characterized. Here, we demonstrate that deep brain stimulation selectively suppresses certain spatially and spectrally segregated resting state subthalamic nucleus-cortical networks. To this end we used a validated and novel approach for performing simultaneous recordings of the subthalamic nucleus and cortex using magnetoencephalography (during concurrent subthalamic nucleus deep brain stimulation). Our results highlight that clinically effective subthalamic nucleus deep brain stimulation suppresses synchrony locally within the subthalamic nucleus in the low beta oscillatory range and furthermore that the degree of this suppression correlates with clinical motor improvement. Moreover, deep brain stimulation relatively selectively suppressed synchronization of activity between the subthalamic nucleus and mesial premotor regions, including the supplementary motor areas. These mesial premotor regions were predominantly coupled to the subthalamic nucleus in the high beta frequency range, but the degree of deep brain stimulation-associated suppression in their coupling to the subthalamic nucleus was not found to correlate with motor improvement. Beta band coupling between the subthalamic nucleus and lateral motor areas was not influenced by deep brain stimulation. Motor cortical coupling with subthalamic nucleus predominantly involved driving of the subthalamic nucleus, with those drives in the higher beta frequency band having much shorter net delays to subthalamic nucleus than those in the lower beta band. These observations raise the

  18. Modeling spatially and spectrally resolved observations to diagnose the formation of elliptical galaxies

    NASA Astrophysics Data System (ADS)

    Snyder, Gregory Frantz

    2013-03-01

    morphologies across cosmic time. In the final chapter, I outline an approach to build a "mock observatory" from cosmological hydrodynamical simulations, with which observations of all types, including at high spatial and spectral resolutions, can be brought to bear in directly constraining the physics of galaxy formation and evolution.

  19. The variable stellar wind of Rigel probed at high spatial and spectral resolution

    NASA Astrophysics Data System (ADS)

    Chesneau, O.; Kaufer, A.; Stahl, O.; Colvinter, C.; Spang, A.; Dessart, L.; Prinja, R.; Chini, R.

    2014-06-01

    Context. Luminous BA-type supergiants are the brightest stars in the visible that can be observed in distant galaxies and are potentially accurate distance indicators. The impact of the variability of the stellar winds on the distance determination remains poorly understood. Aims: Our aim is to probe the inhomogeneous structures in the stellar wind using spectro-interferometric monitoring. Methods: We present a spatially resolved, high-spectral resolution (R = 12 000) K-band temporal monitoring of the bright supergiant β Orionis (Rigel, B8 Iab) using AMBER at the Very Large Telescope Interferometer (VLTI). Rigel was observed in the Brγ line and its nearby continuum once per month over 3 months in 2006-2007, and 5 months in 2009-2010. These unprecedented observations were complemented by contemporaneous optical high-resolution spectroscopy. We analyse the near-IR spectra and visibilities with the 1D non-LTE radiative-transfer code CMFGEN. The differential and closure phase signals are evidence of asymmetries that are interpreted as perturbations of the wind. Results: A systematic visibility decrease is observed across the Brγ line indicating that at a radius of about 1.25 R∗ the photospheric absorption is filled by emission from the wind. During the 2006-2007 period the Brγ and likely the continuum forming regions were larger than in the 2009-2010 epoch. Using CMFGEN we infer a mass-loss rate change of about 20% between the two epochs. We also find time variations in the differential visibilities and phases. The 2006-2007 period is characterised by noticeable variations in the differential visibilities in Doppler position and width and by weak variations in differential and closure phase. The 2009-2010 period is much quieter with virtually no detectable variations in the dispersed visibilities but a strong S-shaped signal is observed in differential phase coinciding with a strong ejection event discernible in the optical spectra. The differential phase signal

  20. Airborne microwave radiometric imaging system

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Li, Futang; Zhang, Zuyin

    1999-09-01

    A dual channel Airborne Microwave Radiometric Imaging system (AMRI) was designed and constructed for regional environment mapping. The system operates at 35GHz, which collects radiation at horizontal and vertical polarized channels. It runs at mechanical conical scanning with 45 degrees incidence angle. Two Cassegrain antennas with 1.5 degrees beamwidth scan the scene alternately and two pseudo- color images of two channels are displayed on the screen of PC in real time. Simultaneously, all parameters of flight and radiometric data are sorted in hard disk for post- processing. The sensitivity of the radiometer (Delta) T equals 0.16K. A new displaying method, unequal size element arc displaying method, is used in image displaying. Several experiments on mobile tower were carried out and the images demonstrate that the AMRI is available to work steadily and accurately.

  1. Radiometric Comparison between Sentinel 2A (S2A) Multispectral Imager (MSI) and Landsat 8 (L8) Operational Land Imager (OLI)

    NASA Astrophysics Data System (ADS)

    Micijevic, E.; Haque, M. O.

    2016-12-01

    With its forty-four year continuous data record, the Landsat image archive provides an invaluable source of information for essential climate variables, global land change studies and a variety of other applications. The latest in the series, Landsat 8, carries the Operational Land Imager (OLI), the sensor with an improved design compared to its predecessors, but with similar radiometric, spatial and spectral characteristics, to provide image data continuity. Sentinel 2A (S2A), launched in June 2015, carries the Multispectral Imager (MSI) that has a number of bands with spectral and radiometric characteristics similar to L8 OLI. As such, it offers an opportunity to augment the Landsat data record through increased frequency of acquisitions, when combined with OLI. In this study, we compared Top-of-Atmosphere (TOA) reflectance of matching spectral bands in MSI and OLI products. Comparison between S2A MSI and L8 OLI sensors was performed using image data acquired near simultaneously primarily over Pseudo Invariant Calibration Site (PICS) Libya 4, but also over other calibration test sites. Spectral differences between the two sensors were accounted for using their spectral filter profiles and a spectral signature of the site derived from EO1 Hyperion hyperspectral imagery. Temporal stability was also assessed through temporal trending of Top-of-Atmosphere (TOA) reflectance measured by the two sensors over PICS. The performed analysis suggests good agreement between the two sensors, within 5% for the costal aerosol band and better than 3% for other matching bands. It is important to note that whenever data from different sensors are used together in a study, the special attention need to be paid to the spectral band differences between the sensors because the necessary spectral difference adjustment is target dependent and may vary a lot from target to target.

  2. Thematic mapper: detailed radiometric and geometric characteristics

    USGS Publications Warehouse

    Kieffer, Hugh

    1983-01-01

    Those radiometric characteristics of the Landsat 4 Thematic Mapper (TM) that can be established without absolute calibration of spectral data have been examined. Subscenes of radiometric all raw data (B-data) were examined on an individual detector basis: areas of uniform radiance were used to characterize subtle radiometric differences and noise problems. A variety of anomalies have been discovered with magnitude of a few digital levels or less: the only problem not addressable by ground processing is irregular width of the digital levels. Essentially all of this non-ideal performance is incorporated in the fully processed (P-type) images, but disguised by the geometric resampling procedure. The overall performance of the Thematic Mapper is a great improvement over previous Landsat scanners. The effective resolution in radiance is degraded by about a factor of two by irregular width of the digital levels. Several detectors have a change of gain with a period of several scans, the largest effect is about 4%. These detectors appear to switch between two response levels during scan direction reversal; there is no apparent periodicity to these changes. This can cause small apparent difference between forward and reverse scans for portions of an image. The high-frequency noise level of each detector was characterized by the standard deviation of the first derivative in the sample direction across a flat field. Coherent sinusoidal noise patterns were determined using one-dimensional Fourier transforms. A "stitching" pattern in Band 1 has a period of 13.8 samples with a peak-to-peak amplitude ranging from 1 to 5 DN. Noise with a period of 3.24 samples is pronounced for most detectors in band 1, to a lesser extent in bands 2, 3, and 4, and below background noise levels in bands 5, 6, and 7. The geometric fidelity of the GSFC film writer used for Thematic Mapper (TM) images was assessed by measurement with accuracy bette than three micrometers of a test grid. A set of 55

  3. Precision radiometric surface temperature (PRST) sensor

    NASA Astrophysics Data System (ADS)

    Daly, James T.; Roberts, Carson; Bodkin, Andrew; Sundberg, Robert; Beaven, Scott; Weinheimer, Jeffrey

    2013-05-01

    There is a need for a Precision Radiometric Surface Temperature (PRST) measurement capability that can achieve noncontact profiling of a sample's surface temperature when heated dynamically during laser processing, aerothermal heating or metal cutting/machining. Target surface temperature maps within and near the heated spot provide critical quantitative diagnostic data for laser-target coupling effectiveness and laser damage assessment. In the case of metal cutting, this type of measurement provides information on plastic deformation in the primary shear zone where the cutting tool is in contact with the workpiece. The challenge in these cases is to measure the temperature of a target while its surface's temperature and emissivity are changing rapidly and with incomplete knowledge of how the emissivity and surface texture (scattering) changes with temperature. Bodkin Design and Engineering, LLC (BDandE), with partners Spectral Sciences, Inc. (SSI) and Space Computer Corporation (SCC), has developed a PRST Sensor that is based on a hyperspectral MWIR imager spanning the wavelength range 2-5 μm and providing a hyperspectral datacube of 20-24 wavelengths at 60 Hz frame rate or faster. This imager is integrated with software and algorithms to extract surface temperature from radiometric measurements over the range from ambient to 2000K with a precision of 20K, even without a priori knowledge of the target's emissivity and even as the target emissivity may be changing with time and temperature. In this paper, we will present a description of the PRST system as well as laser heating test results which show the PRST system mapping target surface temperatures in the range 600-2600K on a variety of materials.

  4. Absolute Radiometric Calibration of EUNIS-06

    NASA Technical Reports Server (NTRS)

    Thomas, R. J.; Rabin, D. M.; Kent, B. J.; Paustian, W.

    2007-01-01

    The Extreme-Ultraviolet Normal-Incidence Spectrometer (EUNIS) is a soundingrocket payload that obtains imaged high-resolution spectra of individual solar features, providing information about the Sun's corona and upper transition region. Shortly after its successful initial flight last year, a complete end-to-end calibration was carried out to determine the instrument's absolute radiometric response over its Longwave bandpass of 300 - 370A. The measurements were done at the Rutherford-Appleton Laboratory (RAL) in England, using the same vacuum facility and EUV radiation source used in the pre-flight calibrations of both SOHO/CDS and Hinode/EIS, as well as in three post-flight calibrations of our SERTS sounding rocket payload, the precursor to EUNIS. The unique radiation source provided by the Physikalisch-Technische Bundesanstalt (PTB) had been calibrated to an absolute accuracy of 7% (l-sigma) at 12 wavelengths covering our bandpass directly against the Berlin electron storage ring BESSY, which is itself a primary radiometric source standard. Scans of the EUNIS aperture were made to determine the instrument's absolute spectral sensitivity to +- 25%, considering all sources of error, and demonstrate that EUNIS-06 was the most sensitive solar E W spectrometer yet flown. The results will be matched against prior calibrations which relied on combining measurements of individual optical components, and on comparisons with theoretically predicted 'insensitive' line ratios. Coordinated observations were made during the EUNIS-06 flight by SOHO/CDS and EIT that will allow re-calibrations of those instruments as well. In addition, future EUNIS flights will provide similar calibration updates for TRACE, Hinode/EIS, and STEREO/SECCHI/EUVI.

  5. Radiometric Characterization of the IKONOS, QuickBird, and OrbView-3 Sensors

    NASA Technical Reports Server (NTRS)

    Holekamp, Kara

    2006-01-01

    Radiometric calibration of commercial imaging satellite products is required to ensure that science and application communities can better understand their properties. Inaccurate radiometric calibrations can lead to erroneous decisions and invalid conclusions and can limit intercomparisons with other systems. To address this calibration need, satellite at-sensor radiance values were compared to those estimated by each independent team member to determine the sensor's radiometric accuracy. The combined results of this evaluation provide the user community with an independent assessment of these commercially available high spatial resolution sensors' absolute calibration values.

  6. Display of spatially-registered Doppler spectral waveforms and three-dimensional vein graft geometry.

    PubMed

    Leotta, Daniel F; Primozich, Jean F; Henderson, Sara M; Karr, Leni N; Bergelin, Robert O; Beach, Kirk W; Zierler, R Eugene

    2005-10-01

    A method has been developed to display Doppler spectral waveforms in lower extremity vein grafts in conjunction with 3-D vessel geometry. Doppler spectral waveforms and cross-sectional images of the vein graft are collected with a custom 3-D ultrasound imaging system. Computer processing generates a display of the Doppler sample volumes registered in 3-D space with a surface reconstruction of the vein graft lumen. An interactive computer interface displays spectral waveforms at user-selected sites in the graft. Summary displays combining spectral waveforms, maximum velocity and cross-sectional area provide a pictorial record of the state of the vein graft along its full length. The method is demonstrated for two patient studies, each at two time points after graft revisions. The graphic display of both hemodynamics and geometry allows rapid assessment of vein graft changes over time.

  7. Radiometric cross-calibration of KOMPSAT-3 with Landsat-8

    NASA Astrophysics Data System (ADS)

    Shin, Dongyoon; Jin, Cheonggil; Ahn, Hoyong; Choi, Chuluong

    2015-10-01

    This paper presents a radiometric cross calibration of KOMPSAT-3 AEISS based on Landsat-8 OLI. Cross calibration between the two sensors using simultaneous image pairs, acquired during an underfly event over the Libya 4 pseudo invariant calibration site (PICS) site. The spectral profile of the target comes from the near-simultaneous EO-1 Hyperion data over these sites for apply Spectral Band Adjustment Factor (SBAF). The results indicate that the Top Of Atmosphere (TOA) reflectance measurements for KOMPSAT-3 agree with Landsat-8 to within 5% after the application of SBAF. To validate radiometric coefficient, comparison TOA reflectance executed in north Virginia, USA. The difference in TOA reflectance was calculated to within a maximum ±1.55%. There was a huge improvement when the standard deviation altered from 0.1 to 0.01, when applying the SBAF. The result of radiometric coefficient presented here appear to be a good standard for maintaining the optical quality of the KOMPSAT-3, for which prelaunch, onboard, and vicarious calibration data are lacking.

  8. Decomposition of Spectral Signatures of Coloured Dissolved Organic Matter Absorption and its Spatial Distribution Along Southeastern Arabian Sea

    NASA Astrophysics Data System (ADS)

    Muhamed Ashraf, P.; Souda, V. P.; Minu, P.

    2016-02-01

    The process of photosynthesis involves the conversion of inorganic carbon into organic carbon and the light availability is the crucial factor affecting photosynthesis in case 2 waters. Coloured dissolved organic matter (CDOM) is a major competitor for light apart from suspended sediments and phytoplankton. The objective was 1) to understand the spatial, vertical and seasonal variability of CDOM by decomposing spectral signatures of absorption in the UV region and to identify the source of CDOM in the study area. The study was carried out for the period 2013 May to 2014 December on monthly basis. Samples from 9 spatial stations, covering estuarine, barmouth and marine region were collected along coastal waters off Kochi, Southeastern Arabian Sea. Two spectral range from 200nm to 400nm were selected for the study, ie. between 275-295 and 350-400. Slope between 275-295nm (S275-295) showed no variation spatially and seasonally except for estuarine station. But slope between 350-400nm (S350-400) exhibited considerable variations spatially, seasonally and vertically. Lower values of ratio between S275-295 and S350-400 in surface waters during monsoon season indicated presence of CDOM with heavy molecular weight of terrigenous origin. Premonsoon and postmonsoon seasons had higher ratio indicating presence of CDOM with lighter molecular weight. Autocthonous origin and degradation of terrigenous matter produces CDOM with light molecular weight. The ratio is found to be increasing from estuary to offshore stations. Hence it is inferred that, the chemical nature of CDOM is affected by both physical and biological components in dynamically unstable case 2 coastal waters. The results presented here shows difference in spectral slope to estimate optical properties of CDOM which is relevant for the description of underwater optics and to the development of ocean colour remote sensing algorithms in the region.

  9. New spectral-spatial imaging algorithm for full EPR spectra of multiline nitroxides and pH sensitive trityl radicals

    NASA Astrophysics Data System (ADS)

    Tseitlin, Mark; Biller, Joshua R.; Elajaili, Hanan; Khramtsov, Valery V.; Dhimitruka, Ilirian; Eaton, Gareth R.; Eaton, Sandra S.

    2014-08-01

    An algorithm is derived and demonstrated that reconstructs an EPR spectral-spatial image from projections with arbitrarily selected gradients. This approach permits imaging wide spectra without the use of the very large sweep widths and gradients that would be required for spectral-spatial imaging with filtered back projection reconstruction. Each projection is defined as the sum of contributions at the set of locations in the object. At each location gradients shift the spectra in the magnetic field domain, which is equivalent to a phase change in the Fourier-conjugate frequency domain. This permits solution of the problem in the frequency domain. The method was demonstrated for 2D images of phantoms consisting of (i) two tubes containing 14N and 15N nitroxide and (ii) two tubes containing a pH sensitive trityl radical at pH 7.0 and 7.2. In each case spectral slices through the image agree well with the full spectra obtained in the absence of gradient.

  10. Development and calibration of UV/VUV radiometric sources

    NASA Technical Reports Server (NTRS)

    Bridges, J. M.

    1993-01-01

    A program exists at NIST to calibrate radiometric sources for the spectral range from 118-350 nm. These include deuterium lamps, hollow-cathode lamps, RF-excited dimer lamps, and wall-stabilized argon arcs. Sources have been calibrated for and used by researchers in solar physics, astrophysics, atmospheric physics (ozone measurements), magnetically controlled fusion, and photobiology. The argon arcs were developed in our laboratory, and provide intense sources of both radiance and irradiance. Calibrations are performed relative to two primary sources, a wall-stabilized hydrogen arc and a 12,000 K black-body line arc, both developed in our laboratory. Also we recently have begun periodic calibrations on the NIST storage ring, SURF II, to insure consistency between our respective radiometric bases. Various sources have been calibrated for space' applications, including several which are flyable. Also, some development and testing of radiometers for semiconductor lithography were recently carried out with an intense argon arc source.

  11. Radiometric cross-calibration of the Terra MODIS and Landsat 7 ETM+ using an invariant desert site

    USGS Publications Warehouse

    Choi, T.; Angal, A.; Chander, G.; Xiong, X.

    2008-01-01

    A methodology for long-term radiometric cross-calibration between the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensors was developed. The approach involves calibration of near-simultaneous surface observations between 2000 and 2007. Fifty-seven cloud-free image pairs were carefully selected over the Libyan desert for this study. The Libyan desert site (+28.55??, +23.39??), located in northern Africa, is a high reflectance site with high spatial, spectral, and temporal uniformity. Because the test site covers about 12 kmx13 km, accurate geometric preprocessing is required to match the footprint size between the two sensors to avoid uncertainties due to residual image misregistration. MODIS Level IB radiometrically corrected products were reprojected to the corresponding ETM+ image's Universal Transverse Mercator (UTM) grid projection. The 30 m pixels from the ETM+ images were aggregated to match the MODIS spatial resolution (250 m in Bands 1 and 2, or 500 m in Bands 3 to 7). The image data from both sensors were converted to absolute units of at-sensor radiance and top-ofatmosphere (TOA) reflectance for the spectrally matching band pairs. For each band pair, a set of fitted coefficients (slope and offset) is provided to quantify the relationships between the testing sensors. This work focuses on long-term stability and correlation of the Terra MODIS and L7 ETM+ sensors using absolute calibration results over the entire mission of the two sensors. Possible uncertainties are also discussed such as spectral differences in matching band pairs, solar zenith angle change during a collection, and differences in solar irradiance models.

  12. Radiometric cross-calibration of the Terra MODIS and Landsat 7 ETM+ using an invariant desert site

    NASA Astrophysics Data System (ADS)

    Choi, Taeyoung; Angal, Amit; Chander, Gyanesh; Xiong, Xiaoxiong

    2008-08-01

    A methodology for long-term radiometric cross-calibration between the Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+) sensors was developed. The approach involves calibration of near-simultaneous surface observations between 2000 and 2007. Fifty-seven cloudfree image pairs were carefully selected over the Libyan desert for this study. The Libyan desert site (+28.55°, +23.39°), located in northern Africa, is a high reflectance site with high spatial, spectral, and temporal uniformity. Because the test site covers about 12 kmx13 km, accurate geometric preprocessing is required to match the footprint size between the two sensors to avoid uncertainties due to residual image misregistration. MODIS Level 1B radiometrically corrected products were reprojected to the corresponding ETM+ image's Universal Transverse Mercator (UTM) grid projection. The 30 m pixels from the ETM+ images were aggregated to match the MODIS spatial resolution (250 m in Bands 1 and 2, or 500 m in Bands 3 to 7). The image data from both sensors were converted to absolute units of at-sensor radiance and top-of atmosphere (TOA) reflectance for the spectrally matching band pairs. For each band pair, a set of fitted coefficients (slope and offset) is provided to quantify the relationships between the testing sensors. This work focuses on long-term stability and correlation of the Terra MODIS and L7 ETM+ sensors using absolute calibration results over the entire mission of the two sensors. Possible uncertainties are also discussed such as spectral differences in matching band pairs, solar zenith angle change during a collection, and differences in solar irradiance models.

  13. Spectral spatial coherence of high-power multi-chip LEDs

    NASA Astrophysics Data System (ADS)

    Chen, Guang-ming; Tao, Hua; Lin, Hui-chuan; Chen, Zi-yang; Pu, Ji-xiong

    2012-11-01

    We investigate the spatial coherence of the light generated from high-power multi-chip red LEDs by using the van Cittert-Zernike theorem. It is theoretically demonstrated that the light generated from multi-chip LEDs evolves into partially coherent light after propagation, and the spatial coherence is increased with the increase of propagation distance. Moreover, the spatial coherence of the light is found to be closely related to the chip distribution of multi-chip LEDs. The distribution of the spatial coherence of the light is experimentally examined by Young's double-slit interference. It is found that the experimental results are consistent with the theoretical ones.

  14. Fast backprojection-based reconstruction of spectral-spatial EPR images from projections with the constant sweep of a magnetic field

    NASA Astrophysics Data System (ADS)

    Komarov, Denis A.; Hirata, Hiroshi

    2017-08-01

    In this paper, we introduce a procedure for the reconstruction of spectral-spatial EPR images using projections acquired with the constant sweep of a magnetic field. The application of a constant field-sweep and a predetermined data sampling rate simplifies the requirements for EPR imaging instrumentation and facilitates the backprojection-based reconstruction of spectral-spatial images. The proposed approach was applied to the reconstruction of a four-dimensional numerical phantom and to actual spectral-spatial EPR measurements. Image reconstruction using projections with a constant field-sweep was three times faster than the conventional approach with the application of a pseudo-angle and a scan range that depends on the applied field gradient. Spectral-spatial EPR imaging with a constant field-sweep for data acquisition only slightly reduces the signal-to-noise ratio or functional resolution of the resultant images and can be applied together with any common backprojection-based reconstruction algorithm.

  15. High speed radiometric measurements of IED detonation fireballs

    NASA Astrophysics Data System (ADS)

    Spidell, Matthew T.; Gordon, J. Motos; Pitz, Jeremey; Gross, Kevin C.; Perram, Glen P.

    2010-04-01

    Continuum emission is predominant in fireball spectral phenomena and in some demonstrated cases, fine detail in the temporal evolution of infrared spectral emissions can be used to estimate size and chemical composition of the device. Recent work indicates that a few narrow radiometric bands may reveal forensic information needed for the explosive discrimination and classification problem, representing an essential step in moving from "laboratory" measurements to a rugged, fieldable system. To explore phenomena not observable in previous experiments, a high speed (10μs resolution) radiometer with four channels spanning the infrared spectrum observed the detonation of nine home made explosive (HME) devices in the < 100lb class. Radiometric measurements indicate that the detonation fireball is well approximated as a single temperature blackbody at early time (0 < t <~ 3ms). The effective radius obtained from absolute intensity indicates fireball growth at supersonic velocity during this time. Peak fireball temperatures during this initial detonation range between 3000.3500K. The initial temperature decay with time (t <~ 10ms) can be described by a simple phenomenological model based on radiative cooling. After this rapid decay, temperature exhibits a small, steady increase with time (10 <~ t <~ 50ms) and peaking somewhere between 1000.1500K-likely the result of post-detonation combustion-before subsequent cooling back to ambient conditions . Radius derived from radiometric measurements can be described well (R2 > 0.98) using blast model functional forms, suggesting that energy release could be estimated from single-pixel radiometric detectors. Comparison of radiometer-derived fireball size with FLIR infrared imagery indicate the Planckian intensity size estimates are about a factor of two smaller than the physical extent of the fireball.

  16. Spatial-spectral flexible optical networking: enabling switching solutions for a simplified and efficient SDM network platform

    NASA Astrophysics Data System (ADS)

    Tomkos, I.; Zakynthinos, P.; Klonidis, D.; Marom, D.; Sygletos, S.; Ellis, A.; Salvadori, E.; Siracusa, D.; Angelou, M.; Papastergiou, G.; Psaila, N.; Ferran, J. F.; Ben-Ezra, S.; Jimenez, F.; Fernández-Palacios, J. P.

    2013-12-01

    The traffic carried by core optical networks grows at a steady but remarkable pace of 30-40% year-over-year. Optical transmissions and networking advancements continue to satisfy the traffic requirements by delivering the content over the network infrastructure in a cost and energy efficient manner. Such core optical networks serve the information traffic demands in a dynamic way, in response to requirements for shifting of traffics demands, both temporally (day/night) and spatially (business district/residential). However as we are approaching fundamental spectral efficiency limits of singlemode fibers, the scientific community is pursuing recently the development of an innovative, all-optical network architecture introducing the spatial degree of freedom when designing/operating future transport networks. Spacedivision- multiplexing through the use of bundled single mode fibers, and/or multi-core fibers and/or few-mode fibers can offer up to 100-fold capacity increase in future optical networks. The EU INSPACE project is working on the development of a complete spatial-spectral flexible optical networking solution, offering the network ultra-high capacity, flexibility and energy efficiency required to meet the challenges of delivering exponentially growing traffic demands in the internet over the next twenty years. In this paper we will present the motivation and main research activities of the INSPACE consortium towards the realization of the overall project solution.

  17. High spectral and spatial resolution X-ray transmission radiography and tomography using a Color X-ray Camera

    NASA Astrophysics Data System (ADS)

    Boone, Matthieu N.; Garrevoet, Jan; Tack, Pieter; Scharf, Oliver; Cormode, David P.; Van Loo, Denis; Pauwels, Elin; Dierick, Manuel; Vincze, Laszlo; Van Hoorebeke, Luc

    2014-01-01

    High resolution X-ray radiography and computed tomography are excellent techniques for non-destructive characterization of an object under investigation at a spatial resolution in the micrometer range. However, as the image contrast depends on both chemical composition and material density, no chemical information is obtained from this data. Furthermore, lab-based measurements are affected by the polychromatic X-ray beam, which results in beam hardening effects. New types of X-ray detectors which provide spectral information on the measured X-ray beam can help to overcome these limitations. In this paper, an energy dispersive CCD detector with high spectral resolution is characterized for use in high resolution radiography and tomography, where a focus is put on the experimental conditions and requirements of both measurement techniques.

  18. High spectral and spatial resolution X-ray transmission radiography and tomography using a Color X-ray Camera.

    PubMed

    Boone, Matthieu N; Garrevoet, Jan; Tack, Pieter; Scharf, Oliver; Cormode, David P; Van Loo, Denis; Pauwels, Elin; Dierick, Manuel; Vincze, Laszlo; Van Hoorebeke, Luc

    2014-01-21

    High resolution X-ray radiography and computed tomography are excellent techniques for non-destructive characterization of an object under investigation at a spatial resolution in the micrometer range. However, as the image contrast depends on both chemical composition and material density, no chemical information is obtained from this data. Furthermore, lab-based measurements are affected by the polychromatic X-ray beam, which results in beam hardening effects. New types of X-ray detectors which provide spectral information on the measured X-ray beam can help to overcome these limitations. In this paper, an energy dispersive CCD detector with high spectral resolution is characterized for use in high resolution radiography and tomography, where a focus is put on the experimental conditions and requirements of both measurement techniques.

  19. Excitons Bound to Nitrogen Pairs in GaAs as Seen by Photoluminescence of High Spectral and Spatial Resolution

    SciTech Connect

    Karaiskaj, D.; Mascarenhas, A.; Klem, J. F.; Volz, K.; Stolz, W.; Adamcyk, M.; Tiedje, T.

    2007-01-01

    High resolution photoluminescence (PL) spectroscopy was performed on high quality bulk GaAs, lightly doped with the nitrogen isoelectronic impurity. The shallowest nitrogen pair bound exciton center labeled as X{sub 1} revealed a total of six transitions. The photoluminescence lines from a small ensemble of nitrogen centers showed polarization dependent intensity. High spectral resolution PL spectroscopy was combined with confocal spectroscopy experiments performed on a GaAs:N/AlGaAs heterostructure. The high spatial resolution achieved by this technique enables us to localize and examine individual nitrogen bound excitons. Similar spectral structure and polarization dependence was observed for individual N-pair centers in GaAs. Both techniques support the C{sub 2v} symmetry of such isoelectronic impurity centers. The comparison between the PL spectra from an ensemble of nitrogen pairs and individual centers demonstrate the ability of the single impurity technique to lift the orientational degeneracy.

  20. High spectral and spatial resolution X-ray transmission radiography and tomography using a Color X-ray Camera

    PubMed Central

    Boone, Matthieu N.; Garrevoet, Jan; Tack, Pieter; Scharf, Oliver; Cormode, David P.; Van Loo, Denis; Pauwels, Elin; Dierick, Manuel; Vincze, Laszlo; Van Hoorebeke, Luc

    2013-01-01

    High resolution X-ray radiography and computed tomography are excellent techniques for non-destructive characterization of an object under investigation at a spatial resolution in the micrometer range. However, as the image contrast depends on both chemical composition and material density, no chemical information is obtained from this data. Furthermore, lab-based measurements are affected by the polychromatic X-ray beam, which results in beam hardening effects. New types of X-ray detectors which provide spectral information on the measured X-ray beam can help to overcome these limitations. In this paper, an energy dispersive CCD detector with high spectral resolution is characterized for use in high resolution radiography and tomography, where a focus is put on the experimental conditions and requirements of both measurement techniques. PMID:24357889

  1. Using a spatial and tabular database to generate statistics from terrain and spectral data for soil surveys

    USGS Publications Warehouse

    Horvath , E.A.; Fosnight, E.A.; Klingebiel, A.A.; Moore, D.G.; Stone, J.E.; Reybold, W.U.; Petersen, G.W.

    1987-01-01

    A methodology has been developed to create a spatial database by referencing digital elevation, Landsat multispectral scanner data, and digitized soil premap delineations of a number of adjacent 7.5-min quadrangle areas to a 30-m Universal Transverse Mercator projection. Slope and aspect transformations are calculated from elevation data and grouped according to field office specifications. An unsupervised classification is performed on a brightness and greenness transformation of the spectral data. The resulting spectral, slope, and aspect maps of each of the 7.5-min quadrangle areas are then plotted and submitted to the field office to be incorporated into the soil premapping stages of a soil survey. A tabular database is created from spatial data by generating descriptive statistics for each data layer within each soil premap delineation. The tabular data base is then entered into a data base management system to be accessed by the field office personnel during the soil survey and to be used for subsequent resource management decisions.Large amounts of data are collected and archived during resource inventories for public land management. Often these data are stored as stacks of maps or folders in a file system in someone's office, with the maps in a variety of formats, scales, and with various standards of accuracy depending on their purpose. This system of information storage and retrieval is cumbersome at best when several categories of information are needed simultaneously for analysis or as input to resource management models. Computers now provide the resource scientist with the opportunity to design increasingly complex models that require even more categories of resource-related information, thus compounding the problem.Recently there has been much emphasis on the use of geographic information systems (GIS) as an alternative method for map data archives and as a resource management tool. Considerable effort has been devoted to the generation of tabular

  2. Algorithmic Foundation of Spectral Rarefaction for Measuring Satellite Imagery Heterogeneity at Multiple Spatial Scales

    PubMed Central

    Rocchini, Duccio

    2009-01-01

    Measuring heterogeneity in satellite imagery is an important task to deal with. Most measures of spectral diversity have been based on Shannon Information theory. However, this approach does not inherently address different scales, ranging from local (hereafter referred to alpha diversity) to global scales (gamma diversity). The aim of this paper is to propose a method for measuring spectral heterogeneity at multiple scales based on rarefaction curves. An algorithmic solution of rarefaction applied to image pixel values (Digital Numbers, DNs) is provided and discussed. PMID:22389600

  3. Sensitivity of a frequency-selective electrode based on spatial spectral properties of the extracellular AP of myelinated nerve fibers.

    PubMed

    Rossel, Olivier; Soulier, Fabien; Bernard, Serge; Cathébras, Guy

    2011-01-01

    In the context of functional electrical stimulation, neural recording is one of the main issues. For instance, the control of the limbs in people with motor deficiencies needs information about the muscle lengths and speeds that can be extracted from electroneurograms (ENG) carried on afferent peripheral nerves. The aim of this study is to propose an non-invasive and spatial-selective electrode (because specific informations are carried into different fascicles). To do so, we investigate the spatial properties of an extracellular action potential (AP). This properties are described qualitatively and quantitatively using analytical study on an inhomogeneous an anisotropic nerve model. Then, a spectral analysis on this spatial signal discriminates the different frequency components. Low spatial frequencies represent the global shape of the signal, whereas high frequencies are related to the type of fibers. We show that the latter is rapidly attenuated with the distance and thus, being a local phenomenon, can be used as a selective measurement. Finally, we propose a spatial filtering based on electrode design and an electronic architecture to extract this high frequencies.

  4. Kite aerial photography for low-cost, ultra-high spatial resolution multi-spectral mapping of intertidal landscapes.

    PubMed

    Bryson, Mitch; Johnson-Roberson, Matthew; Murphy, Richard J; Bongiorno, Daniel

    2013-01-01

    Intertidal ecosystems have primarily been studied using field-based sampling; remote sensing offers the ability to collect data over large areas in a snapshot of time that could complement field-based sampling methods by extrapolating them into the wider spatial and temporal context. Conventional remote sensing tools (such as satellite and aircraft imaging) provide data at limited spatial and temporal resolutions and relatively high costs for small-scale environmental science and ecologically-focussed studies. In this paper, we describe a low-cost, kite-based imaging system and photogrammetric/mapping procedure that was developed for constructing high-resolution, three-dimensional, multi-spectral terrain models of intertidal rocky shores. The processing procedure uses automatic image feature detection and matching, structure-from-motion and photo-textured terrain surface reconstruction algorithms that require minimal human input and only a small number of ground control points and allow the use of cheap, consumer-grade digital cameras. The resulting maps combine imagery at visible and near-infrared wavelengths and topographic information at sub-centimeter resolutions over an intertidal shoreline 200 m long, thus enabling spatial properties of the intertidal environment to be determined across a hierarchy of spatial scales. Results of the system are presented for an intertidal rocky shore at Jervis Bay, New South Wales, Australia. Potential uses of this technique include mapping of plant (micro- and macro-algae) and animal (e.g. gastropods) assemblages at multiple spatial and temporal scales.

  5. Kite Aerial Photography for Low-Cost, Ultra-high Spatial Resolution Multi-Spectral Mapping of Intertidal Landscapes

    PubMed Central

    Bryson, Mitch; Johnson-Roberson, Matthew; Murphy, Richard J.; Bongiorno, Daniel

    2013-01-01

    Intertidal ecosystems have primarily been studied using field-based sampling; remote sensing offers the ability to collect data over large areas in a snapshot of time that could complement field-based sampling methods by extrapolating them into the wider spatial and temporal context. Conventional remote sensing tools (such as satellite and aircraft imaging) provide data at limited spatial and temporal resolutions and relatively high costs for small-scale environmental science and ecologically-focussed studies. In this paper, we describe a low-cost, kite-based imaging system and photogrammetric/mapping procedure that was developed for constructing high-resolution, three-dimensional, multi-spectral terrain models of intertidal rocky shores. The processing procedure uses automatic image feature detection and matching, structure-from-motion and photo-textured terrain surface reconstruction algorithms that require minimal human input and only a small number of ground control points and allow the use of cheap, consumer-grade digital cameras. The resulting maps combine imagery at visible and near-infrared wavelengths and topographic information at sub-centimeter resolutions over an intertidal shoreline 200 m long, thus enabling spatial properties of the intertidal environment to be determined across a hierarchy of spatial scales. Results of the system are presented for an intertidal rocky shore at Jervis Bay, New South Wales, Australia. Potential uses of this technique include mapping of plant (micro- and macro-algae) and animal (e.g. gastropods) assemblages at multiple spatial and temporal scales. PMID:24069206

  6. Detectability of Planetary Characteristics from Spatially and Spectrally-Resolved Models of Terrestrial Planets: Mars and Earth

    NASA Astrophysics Data System (ADS)

    Tinetti, G.; Meadows, V. S.; Crisp, D.; Fong, W.; Snively, H.; Velusamy, T.

    2003-05-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) mission is to detect and characterize extrasolar terrestrial planets. However, the first generation of instruments for studying extrasolar planets are expected to provide only disk-averaged spectra with modest spectral resolution and signal to noise. As a part of the NASA Astrobiology Institute's Virtual Planetary Laboratory (VPL, V. Meadows, PI) we are exploring what can be learned about a planet's surface and atmospheric properties from disk-averaged spectra at a number of spectral resolutions at visible and IR wavelengths. We are using a spectrum resolving (line-by-line) atmospheric/surface radiative transfer model (SMART, D. Crisp) and atmospheric and surface data for Earth, Mars, Venus and Titan to generate a database of spatially resolved synthetic spectra for a range of illumination conditions (phase angles) and viewing geometries. These results are then processed with a model that resamples the spatially resolved spectra to create a synthetic, disk-averaged view of the planet from a specific viewing geometry. To validate these methods, we have compared observational data with our synthetic spectra of Mars and Earth. We will present a complete study of Mars, and the first results for Earth, including disk-averaged synthetic spectra, images and the spectral variability at visible and mid-IR wavelengths as a function of viewing angle. We have also simulated an increasingly frozen Mars, and have studied the detectability of CO2 ice in the disk averaged spectrum, using a TPF instrument simulator. We have determined that surface CO2 ice can be spectrally identified in a TPF mid-IR spectrum of a disk-averaged Mars, even at low resolution, if the ice cap extends down to at least 50 degrees latitude from the pole. This work is supported by the NASA Astrobiology Institute.

  7. The Radiometric Map of Australia

    NASA Astrophysics Data System (ADS)

    Minty, Brian; Franklin, Ross; Milligan, Peter; Richardson, Murray; Wilford, John

    2009-12-01

    Geoscience Australia and the Australian State and Territory Geological Surveys have systematically surveyed most of the Australian continent over the past 40 years using airborne gamma-ray spectrometry to map potassium, uranium and thorium elemental concentrations at the Earth's surface. However, the individual surveys that comprise the national gamma-ray spectrometric radioelement database are not all registered to the same datum. This limits the usefulness of the database as it is not possible to easily combine surveys into regional compilations or make accurate comparisons between radiometric signatures in different survey areas. To solve these problems, Geoscience Australia has undertaken an Australia-Wide Airborne Geophysical Survey (AWAGS), funded under the Australian Government's Onshore Energy Security Program, to serve as a radioelement baseline for all current and future airborne gamma-ray spectrometric surveys in Australia. The AWAGS survey has been back-calibrated to the International Atomic Energy Agency's (IAEA) radioelement datum. We have used the AWAGS data to level the national radioelement database by estimating survey correction factors that, once applied, minimise both the differences in radioelement estimates between surveys (where these surveys overlap) and the differences between the surveys and the AWAGS traverses. The database is thus effectively levelled to the IAEA datum. The levelled database has been used to produce the first `Radiometric Map of Australia' - levelled and merged composite potassium (% K), uranium (ppm eU) and thorium (ppm eTh) grids over Australia at 100m resolution. Interpreters can use the map to reliably compare the radiometric signatures observed over different parts of Australia. This enables the assessment of key mineralogical and geochemical properties of bedrock and regolith materials from different geological provinces and regions with contrasting landscape histories.

  8. On the spectral-spatial instability of a light wave in a medium with cubic nonlinearity

    SciTech Connect

    Afanas'ev, Anatolii A; Volkov, V M

    2003-11-30

    Based on the analysis of frequency-nondegenerate four-photon parametric scattering, the spectral-angular dependences of the increments of perturbing modes are obtained in the field of an intense light wave propagating in a medium with cubic nonlinearity. (nonlinear optical phenomena)

  9. Using the spatial and spectral precision of satellite imagery to predict wildlife occurrence patterns.

    Treesearch

    Edward J. Laurent; Haijin Shi; Demetrios Gatziolis; Joseph P. LeBouton; Michael B. Walters; Jianguo. Liu

    2005-01-01

    We investigated the potential of using unclassified spectral data for predicting the distribution of three bird species over a -400,000 ha region of Michigan's Upper Peninsula using Landsat ETM+ imagery and 433 locations sampled for birds through point count surveys. These species, Black-throated Green Warbler, Nashville Warbler, and Ovenbird. were known to be...

  10. RapidEye constellation relative radiometric accuracy measurement using lunar images

    NASA Astrophysics Data System (ADS)

    Steyn, Joe; Tyc, George; Beckett, Keith; Hashida, Yoshi

    2009-09-01

    The RapidEye constellation includes five identical satellites in Low Earth Orbit (LEO). Each satellite has a 5-band (blue, green, red, red-edge and near infrared (NIR)) multispectral imager at 6.5m GSD. A three-axes attitude control system allows pointing the imager of each satellite at the Moon during lunations. It is therefore possible to image the Moon from near identical viewing geometry within a span of 80 minutes with each one of the imagers. Comparing the radiometrically corrected images obtained from each band and each satellite allows a near instantaneous relative radiometric accuracy measurement and determination of relative gain changes between the five imagers. A more traditional terrestrial vicarious radiometric calibration program has also been completed by MDA on RapidEye. The two components of this program provide for spatial radiometric calibration ensuring that detector-to-detector response remains flat, while a temporal radiometric calibration approach has accumulated images of specific dry dessert calibration sites. These images are used to measure the constellation relative radiometric response and make on-ground gain and offset adjustments in order to maintain the relative accuracy of the constellation within +/-2.5%. A quantitative comparison between the gain changes measured by the lunar method and the terrestrial temporal radiometric calibration method is performed and will be presented.

  11. Classification of crystal defects in multicrystalline silicon solar cells and wafer using spectrally and spatially resolved photoluminescence

    NASA Astrophysics Data System (ADS)

    Lausch, D.; Mehl, T.; Petter, K.; Svarstad Flø, A.; Burud, I.; Olsen, E.

    2016-02-01

    In this contribution, spectral photoluminescence (SPL) imaging detecting both the spectral distribution and the lateral position is applied on recombination active defects in multicrystalline silicon solar cells and wafers. The result is analysed by a Multivariate Curve Resolution (MCR) algorithm using the spectral photoluminescence response and their positions. (i) Without any pre-assumptions made, the algorithm distinguishes four different recombination active defect types. Looking at the spatial distribution, it is shown that two of these defect types coincide with two defect types that have been distinguished on solar cell level using an analysis of forward and reverse biased electroluminescence (denoted as Type-A and -B) previously. (ii) Using SPL, all previously classified defects can also be distinguished at the wafer level. Therefore, the defects limiting the solar cell efficiency are already present in the wafer material and not introduced by the solar cell process. This is of particular interest for the question of how to predict the solar cell efficiency based on the PL measurements at the wafer level. The SPL is able to distinguish between the recombination activity of the dominant Type-A and -B defects that cannot be distinguished by classical PL measurements of the band-to-band recombination at the wafer level. The technique also highlights the changes in recombination activity of the given defects throughout the fabrication process. (iii) Additionally, it is shown that the spectral peak positions of Type-A defects coincide with the known D3 and D4 lines and of Type-B defects with the D1 line on both solar cell and wafer level. Two further defects are captured by the MCR algorithm denoted as Type-VID3 and Type-D07 defects occurring as spot-like defects in isolated positions. Their spectral PL response is analysed as well.

  12. Application of spectral and spatial indices for specific class identification in Airborne Prism EXperiment (APEX) imaging spectrometer data for improved land cover classification

    NASA Astrophysics Data System (ADS)

    Kallepalli, Akhil; Kumar, Anil; Khoshelham, Kourosh; James, David B.

    2016-10-01

    Hyperspectral remote sensing's ability to capture spectral information of targets in very narrow bandwidths gives rise to many intrinsic applications. However, the major limiting disadvantage to its applicability is its dimensionality, known as the Hughes Phenomenon. Traditional classification and image processing approaches fail to process data along many contiguous bands due to inadequate training samples. Another challenge of successful classification is to deal with the real world scenario of mixed pixels i.e. presence of more than one class within a single pixel. An attempt has been made to deal with the problems of dimensionality and mixed pixels, with an objective to improve the accuracy of class identification. In this paper, we discuss the application of indices to cope with the disadvantage of the dimensionality of the Airborne Prism EXperiment (APEX) hyperspectral Open Science Dataset (OSD) and to improve the classification accuracy using the Possibilistic c-Means (PCM) algorithm. This was used for the formulation of spectral and spatial indices to describe the information in the dataset in a lesser dimensionality. This reduced dimensionality is used for classification, attempting to improve the accuracy of determination of specific classes. Spectral indices are compiled from the spectral signatures of the target and spatial indices have been defined using texture analysis over defined neighbourhoods. The classification of 20 classes of varying spatial distributions was considered in order to evaluate the applicability of spectral and spatial indices in the extraction of specific class information. The classification of the dataset was performed in two stages; spectral and a combination of spectral and spatial indices individually as input for the PCM classifier. In addition to the reduction of entropy, while considering a spectral-spatial indices approach, an overall classification accuracy of 80.50% was achieved, against 65% (spectral indices only) and

  13. Spatial dispersion effects in spectral line broadening by pressure. I. The Bouguer Law and absorption coefficient

    SciTech Connect

    Cherkasov, M.R.

    1995-04-01

    Based on the general principles of semiclassical electrodynamics, the Bouguer law is derived, and the expression for the absorption coefficient is obtained, formally including all effects related to the phenomenon of spatial dispersion.

  14. Uncoupling the complexity of forest soil variation: influence of terrain attributes, spectral indices, and spatial variability

    EPA Science Inventory

    Growing concern over climate and management induced changes to soil nutrient status has prompted interest in understanding the spatial distribution of forest soil properties. Recent advancements in remotely sensed geospatial technologies are providing an increasing array of data...

  15. Uncoupling the complexity of forest soil variation: influence of terrain attributes, spectral indices, and spatial variability

    EPA Science Inventory

    Growing concern over climate and management induced changes to soil nutrient status has prompted interest in understanding the spatial distribution of forest soil properties. Recent advancements in remotely sensed geospatial technologies are providing an increasing array of data...

  16. Assessment of the Short-Term Radiometric Stability between Terra MODIS and Landsat 7 ETM+ Sensors

    NASA Technical Reports Server (NTRS)

    Choi, Taeyoung; Xiong, Xiaxiong; Chander, G.; Angal, Amit

    2009-01-01

    The Landsat 7 (L7) Enhanced Thematic Mapper (ETM+) sensor was launched on April 15th, 1999 and has been in operation for over nine years. It has six reflective solar spectral bands located in the visible and shortwave infrared part of the electromagnetic spectrum (0.5 - 2.5 micron) at a spatial resolution of 30 m. The on-board calibrators are used to monitor the on-orbit sensor system changes. The ETM+ performs solar calibrations using on-board Full Aperture Solar Calibrator (FASC) and the Partial Aperture Solar Calibrator (PASC). The Internal Calibrator Lamp (IC) lamps, a blackbody and shutter optics constitute the on-orbit calibration mechanism for ETM+. On 31 May 2003, a malfunction of the scan-line corrector (SLC) mirror assembly resulted in the loss of approximately 22% of the normal scene area. The missing data affects most of the image with scan gaps varying in width from one pixel or less near the centre of the image to 14 pixels along the east and west edges of the image, creating a wedge-shaped pattern. However, the SLC failure has no impacts on the radiometric performance of the valid pixels. On December 18, 1999, the Moderate Resolution Imaging Spectroradiometer (MODIS) Proto-Flight Model (PFM) was launched on-board the NASA's EOS Terra spacecraft. Terra MODIS has 36 spectral bands with wavelengths ranging from 0.41 to 14.5 micron and collects data over a wide field of view angle (+/-55 deg) at three nadir spatial resolutions of 250 m, 500 in 1 km for bands 1 to 2, 3 to 7, and 8 to 36, respectively. It has 20 reflective solar bands (RSB) with spectral wavelengths from 0.41 to 2.1 micron. The RSB radiometric calibration is performed by using on-board solar diffuser (SD), solar diffuser stability monitor (SDSM), space-view (SV), and spectro-radiometric calibration assembly (SRCA). Through the SV port, periodic lunar observations are used to track radiometric response changes at different angles of incidence (AOI) of the scan mirror. As a part of the AM

  17. Nonlinear spatial focusing in random layered media by spectral pulse shaping

    NASA Astrophysics Data System (ADS)

    Han, Alex C.; Milner, Valery

    2016-02-01

    We demonstrate numerically a method of focusing two-photon fields inside one-dimensional random media. The approach is based on coherent control of backscattering achieved by adaptive spectral pulse shaping. The spectral phases of a femtosecond laser pulse are adjusted for the constructive interference of its backward-traveling components, resulting in an enhanced reflection from within the random system. A delayed forward-propagating second pulse overlaps with the controlled reflection, increasing the interpulse multiphoton field at a location determined by the delay between the two pulses. The technique is shown to be robust against the variations of the disorder and to work with realistic pulse-shaping parameters, hence enabling applications in controlling random lasing and multiphoton imaging in scattering materials.

  18. Radiometric studies of Mycobacterium lepraemurium.

    PubMed

    Camargo, E E; Larson, S M; Tepper, B S; Wagner, H N

    1976-01-01

    The radiometric method has been applied for studying the metabolism of M. lepraemurium and the conditions which might force or inhibit its metabolic activity in vitro. These organisms assimilate and oxidize (U-14C) glycerol, and (U-14C) acetate, but are unable to oxidize (U-14C) glucose, (U-14C) pyruvate, (U-14C) glycine and 14C-formate. When incubated at 30 degrees C M. lepraemurium oxidizes (U-14C) acetate to 14CO2 faster than 37 degrees C. The smae effect was observed with increasing concentrations of polysorbate 80 (Tween 80), or the 14C-substrate. No change in metabolic rate was observed when the organisms were kept at -20 degrees C for 12 days. Although tried several times, it was not possible to demonstrate any "inhibitors" of bacterial metabolism in the reaction system. The radiometric method seems to be an important tool for studying metabolic pathways and the influence of physical and biochemical factors on the metabolism of M. lepraemurium in vitro.

  19. Spectral and Spatial-Based Classification for Broad-Scale Land Cover Mapping Based on Logistic Regression

    PubMed Central

    Mallinis, Georgios; Koutsias, Nikos

    2008-01-01

    Improvement of satellite sensor characteristics motivates the development of new techniques for satellite image classification. Spatial information seems to be critical in classification processes, especially for heterogeneous and complex landscapes such as those observed in the Mediterranean basin. In our study, a spectral classification method of a LANDSAT-5 TM imagery that uses several binomial logistic regression models was developed, evaluated and compared to the familiar parametric maximum likelihood algorithm. The classification approach based on logistic regression modelling was extended to a contextual one by using autocovariates to consider spatial dependencies of every pixel with its neighbours. Finally, the maximum likelihood algorithm was upgraded to contextual by considering typicality, a measure which indicates the strength of class membership. The use of logistic regression for broad-scale land cover classification presented higher overall accuracy (75.61%), although not statistically significant, than the maximum likelihood algorithm (64.23%), even when the latter was refined following a spatial approach based on Mahalanobis distance (66.67%). However, the consideration of the spatial autocovariate in the logistic models significantly improved the fit of the models and increased the overall accuracy from 75.61% to 80.49%. PMID:27873976

  20. Enhancing spatial resolution for spectral μCT with aperture encoding

    NASA Astrophysics Data System (ADS)

    Getzin, Matthew; Liu, Tianyu; Yang, Qingsong; Chen, Mianyi; Cong, Wenxiang; Xu, George; Wang, Ge

    2016-09-01

    Recent advances in X-ray imaging technologies have paved the way for use of energy-discriminating photon-counting detector arrays. These detectors show promise in clinical and preclinical applications. Multi-energy or spectral CT images can be visualized in multi-colors. Despite the advantages offered by the spectral dimension of acquired data, higher image resolution is still desirable, especially in challenging tasks such as on-site studies of resected pathological tissues. Here we propose to enhance image resolution of a spectral X-ray imaging system by partially blocking each detector element with an absorption grating (for reduced aperture), commonly used for Talbot-Lau interferometry. After acquiring X-ray data at an initial grating-detector configuration, the grating is shifted to expose previously blocked portions so that each measurement contains new information. All the acquired data are then combined into an augmented system matrix and subsequently reconstructed using an iterative algorithm. Our proof of concept simulations are performed with MCNP6.1 code and the experiment was performed using a Hamamatsu microfocus X-ray source, an absorption grating, and an Xray camera. Our results demonstrate that the gratings commonly used for x-ray phase-contrast imaging have a utility for super-resolution imaging performance.

  1. Mapping and modeling the urban landscape in Bangkok, Thailand: Physical-spectral-spatial relations of population-environmental interactions

    NASA Astrophysics Data System (ADS)

    Shao, Yang

    This research focuses on the application of remote sensing, geographic information systems, statistical modeling, and spatial analysis to examine the dynamics of urban land cover, urban structure, and population-environment interactions in Bangkok, Thailand, with an emphasis on rural-to-urban migration from rural Nang Rong District, Northeast Thailand to the primate city of Bangkok. The dissertation consists of four main sections: (1) development of remote sensing image classification and change-detection methods for characterizing imperviousness for Bangkok, Thailand from 1993-2002; (2) development of 3-D urban mapping methods, using high spatial resolution IKONOS satellite images, to assess high-rises and other urban structures; (3) assessment of urban spatial structure from 2-D and 3-D perspectives; and (4) an analysis of the spatial clustering of migrants from Nang Rong District in Bangkok and the neighborhood environments of migrants' locations. Techniques are developed to improve the accuracy of the neural network classification approach for the analysis of remote sensing data, with an emphasis on the spectral unmixing problem. The 3-D building heights are derived using the shadow information on the high-resolution IKONOS image. The results from the 2-D and 3-D mapping are further examined to assess urban structure and urban feature identification. This research contributes to image processing of remotely-sensed images and urban studies. The rural-urban migration process and migrants' settlement patterns are examined using spatial statistics, GIS, and remote sensing perspectives. The results show that migrants' spatial clustering in urban space is associated with the source village and a number of socio-demographic variables. In addition, the migrants' neighborhood environments in urban setting are modeled using a set of geographic and socio-demographic variables, and the results are scale-dependent.

  2. Toward noninvasive optical human brain mapping: improvements of the spectral, temporal, and spatial resolution of near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Heekeren, Hauke R.; Wenzel, Rudiger; Obrig, Hellmuth; Ruben, Jan; Ndayisaba, J.-P.; Luo, Qingming; Dale, A.; Nioka, Shoko; Kohl-Bareis, Matthias; Dirnagl, Ulrich; Villringer, Arno; Chance, Britton

    1997-08-01

    Near-infrared spectroscopy (NIRS) can detect changes in cerebral hemoglobin oxygenation in response to motor, visual or cognitive stimulation. This study explored potential improvements for functional human brain mapping with NIRS: (1) So far, only primary cortical areas, like motor cortex or primary visual areas were studied. We tested the feasibility of identifying an extrastriate visual motion area (MT) with single site NIRS. (2) The temporal resolution of commercial systems is on the order of seconds and their spectral resolution is poor. We tested the feasibility of the detection of cerebral hemoglobin oxygenation changes during visual stimulation at high temporal (100 ms) and spectral resolution (5 nm) using a whole spectrum approach (CCD-NIRS). (3) The spatial resolution of commercial systems is poor. In this study we used a 16 channel functional NIRS-imaging device to test the feasibility of mapping changes in cortical blood volume during visual stimulation (over primary and secondary areas). We show that (1) even conventional single site NIRS allows to identify secondary visual areas, (2) a CCD-NIRS system affords a high temporal (100 ms) and spectral (5 nm) resolution for the detection of changes in cerebral hemoglobin oxygenation during visual stimulation, (3) functional NIRS- imaging can localize focal blood volume changes over both primary and secondary cortical areas.

  3. Radiometric Normalization of Large Airborne Image Data Sets Acquired by Different Sensor Types

    NASA Astrophysics Data System (ADS)

    Gehrke, S.; Beshah, B. T.

    2016-06-01

    Generating seamless mosaics of aerial images is a particularly challenging task when the mosaic comprises a large number of im-ages, collected over longer periods of time and with different sensors under varying imaging conditions. Such large mosaics typically consist of very heterogeneous image data, both spatially (different terrain types and atmosphere) and temporally (unstable atmo-spheric properties and even changes in land coverage). We present a new radiometric normalization or, respectively, radiometric aerial triangulation approach that takes advantage of our knowledge about each sensor's properties. The current implementation supports medium and large format airborne imaging sensors of the Leica Geosystems family, namely the ADS line-scanner as well as DMC and RCD frame sensors. A hierarchical modelling - with parameters for the overall mosaic, the sensor type, different flight sessions, strips and individual images - allows for adaptation to each sensor's geometric and radiometric properties. Additional parameters at different hierarchy levels can compensate radiome-tric differences of various origins to compensate for shortcomings of the preceding radiometric sensor calibration as well as BRDF and atmospheric corrections. The final, relative normalization is based on radiometric tie points in overlapping images, absolute radiometric control points and image statistics. It is computed in a global least squares adjustment for the entire mosaic by altering each image's histogram using a location-dependent mathematical model. This model involves contrast and brightness corrections at radiometric fix points with bilinear interpolation for corrections in-between. The distribution of the radiometry fixes is adaptive to each image and generally increases with image size, hence enabling optimal local adaptation even for very long image strips as typi-cally captured by a line-scanner sensor. The normalization approach is implemented in HxMap software. It has been

  4. Mapping Robinia Pseudoacacia Forest Health Conditions by Using Combined Spectral, Spatial and Textureal Information Extracted from Ikonos Imagery

    NASA Astrophysics Data System (ADS)

    Wang, H.; Zhao, Y.; Pu, R.; Zhang, Z.

    2016-10-01

    In this study grey-level co-occurrence matrix (GLCM) textures and a local statistical analysis Getis statistic (Gi), computed from IKONOS multispectral (MS) imagery acquired from the Yellow River Delta in China, along with a random forest (RF) classifier, were used to discriminate Robina pseudoacacia tree health levels. The different RF classification results of the three forest health conditions were created: (1) an overall accuracy (OA) of 79.5% produced using the four MS band reflectances only; (2) an OA of 97.1% created with the eight GLCM features calculated from IKONOS Band 4 with the optimal window size of 13 × 13 and direction 45°; (3) an OA of 94.0% created using the four Gi features calculated from the four IKONOS MS bands with the optimal distance value of 5 and Queen's neighborhood rule; and (4) an OA of 96.9% created with the combined 16 spectral (four), spatial (four), and textural (eight) features. The experimental results demonstrate that (a) both textural and spatial information was more useful than spectral information in determining the Robina pseudoacacia forest health conditions; and (b) IKONOS NIR band was more powerful than visible bands in quantifying varying degree of forest crown dieback.

  5. Spectral/spatial data fusion and neural networks for vegetation understory information extraction from hyperspectral airborne images

    NASA Astrophysics Data System (ADS)

    Binaghi, Elisabetta; Gallo, Ignazio; Boschetti, Mirco; Brivio, Pietro A.

    2004-02-01

    In this paper, we propose a method able to fuse spectral information with spatial contextual information in order to solve "operationally" classification problem. The salient aspect of the method is the integration of heterogeneous data within a Multi-Layer Perceptron model. Spatial and spectral relationships are not explicitly formalized in an attempt to limit design and computational complexity; raw data are instead presented directly as input to the neural network classifier. The method in particular addresses new open problems in processing hyperspectral and high resolution data finding solution for multisource analysis. Experimental results in real domain show this fusing approach is able to produce accurate classification. The method in fact is able to handle the problem of a volumetric mixture typical of natural forest ecosystems identifying the different surfaces present under the tree canopy. The understory map, produced by the neural classification method, was used as input to the inversion of radiative transfer models that show a significant increase in the retrieval of important biophysical vegetation parameter.

  6. Preliminary radiometric calibration assessment of ALOS AVNIR-2

    USGS Publications Warehouse

    Bouvet, M.; Goryl, P.; Chander, G.; Santer, R.; Saunier, S.

    2008-01-01

    This paper summarizes the activities carried out in the frame of the data quality activities of the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) sensor onboard the Advanced Land Observing Satellite (ALOS). Assessment of the radiometric calibration of the AVNIR-2 multi-spectral imager is achieved via three intercomparisons to currently flying sensors over the Libyan desert, during the first year of operation. AU three methodologies indicate a slight underestimation of AVNIR-2 in band 1 by 4 to 7% with respect to other sensors radiometric scale. Band 2 does not show any obvious bias. Results for band 3 are affected by saturation due to inappropriate gain setting. Two methodologies indicate no significant bias in band 4. Preliminary results indicate possible degradations of the AVNIR-2 channels, which, when modeled as an exponentially decreasing functions, have time constants of respectively 13.2 %.year-1, 8.8%.year-1 and 0.1%.year-1 in band 1, 2 and 4 (with respect to the radiometric scale of the MEdium Resolution Imaging Spectrometer, MERIS). Longer time series of AVNIR-2 data are needed to draw final conclusions. ?? 2007 IEEE.

  7. A new radiometric unit of measure to characterize SWIR illumination

    NASA Astrophysics Data System (ADS)

    Richards, A.; Hübner, M.

    2017-05-01

    We propose a new radiometric unit of measure we call the `swux' to unambiguously characterize scene illumination in the SWIR spectral band between 0.8μm-1.8μm, where most of the ever-increasing numbers of deployed SWIR cameras (based on standard InGaAs focal plane arrays) are sensitive. Both military and surveillance applications in the SWIR currently suffer from a lack of a standardized SWIR radiometric unit of measure that can be used to definitively compare or predict SWIR camera performance with respect to SNR and range metrics. We propose a unit comparable to the photometric illuminance lux unit; see Ref. [1]. The lack of a SWIR radiometric unit becomes even more critical if one uses lux levels to describe SWIR sensor performance at twilight or even low light condition, since in clear, no-moon conditions in rural areas, the naturally-occurring SWIR radiation from nightglow produces a much higher irradiance than visible starlight. Thus, even well-intentioned efforts to characterize a test site's ambient illumination levels in the SWIR band may fail based on photometric instruments that only measure visible light. A study of this by one of the authors in Ref. [2] showed that the correspondence between lux values and total SWIR irradiance in typical illumination conditions can vary by more than two orders of magnitude, depending on the spectrum of the ambient background. In analogy to the photometric lux definition, we propose the SWIR irradiance equivalent `swux' level, derived by integration over the scene SWIR spectral irradiance weighted by a spectral sensitivity function S(λ), a SWIR analog of the V(λ) photopic response function.

  8. New CRISM Along-Track Oversampled Observations and Implications for Spectral Mapping at Fine Spatial Scales

    NASA Astrophysics Data System (ADS)

    Coman, E. I.; Arvidson, R. E.; Stein, N.; Murchie, S. L.; McGovern, A.; Seelos, K. D.; Seelos, F. P.; Humm, D. C.

    2013-12-01

    The Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is a hyperspectral line scanner imaging system (0.362-3.920 micrometers at 6.55 nm/channel) that was designed to acquire targeted images at ~18 m/pixel spatial sampling. Past experiments have shown that by appropriately commanding the gimbal system, CRISM can also collect Along-Track Oversampled (ATO) observations with overlapping pixels that can be sharpened to along-track spatial resolutions as fine as 5 m/pixel. These observations were impossible to sharpen to a constant along-track spatial resolution within scenes because pixel overlap varied significantly due to irregularities in gimbal motion during imaging of targets. A new observational scheme has been implemented in which gimbaling has been adjusted to keep overlap constant, allowing consistent regularization and sharpening across the entire scene. We demonstrate two processing approaches for spatial sharpening of several scenes acquired with the new gimbaling approach. The scenes are: 1. A recent crater with dark ejecta located at 23.7N, 220.1E (areocentric) ATO00029FC9; 2. Layered rocks uplifted in crater near Solis Dorsa located at 23.14N, 281.37E ATO00029F00, and 3. Dikes in Valles Marineris Coprates Chasma located at 15.02N, 306.96 ATO00029EFD. The two methods are Tikhonov damped least squares spatial sharpening implemented in one dimensional and two dimensional schemes. The Tikhonov method for spatial sharpening replaces the overlapping pixels with smaller, regularly spaced pixels by minimizing the sums of squares of deviations between the observed data matrix and a matrix of regularized, smaller-sized pixels premultiplied by the imaging system transfer function, including ground motion smear. A side constraint is introduced to minimize the sums of squares of deviations of first derivatives for the regularized pixel matrix. This side constraint minimizes noise, and the extent of this minimization is

  9. Visualization of the spatial and spectral signals of orb-weaving spiders, Nephila pilipes, through the eyes of a honeybee.

    PubMed

    Chiao, Chuan-Chin; Wu, Wen-Yen; Chen, Sheng-Hui; Yang, En-Cheng

    2009-07-01

    It is well known that the honeybee has good color vision. However, the spectral range in which the bee can see is different from that of the human eye. To study how bees view their world of colors, one has to see through the eyes of the bee, not the eyes of a human. A conventional way to examine the color signals that animals can detect is to measure the surface reflectance spectra and compute the quantum catches of each photoreceptor type based on its known spectral sensitivity. Color signal and color contrast are then determined from the loci of these quantum catches in the color space. While the point-by-point measurements of the reflectance spectra using a standard spectrometer have yielded a significant amount of data for analyzing color signals, the lack of spatial information and low sampling efficiency constrain their applications. Using a special filter coating technique, a set of filters with transmission spectra that were closely matched to the bee's sensitivity spectra of three photoreceptor types (UV, blue, and green) was custom made. By placing these filters in front of a UV/VIS-sensitive CCD camera and acquiring images sequentially, we could collect images of a bee's receptor with only three shots. This allowed a direct visualization of how bees view their world in a pseudo-color RGB display. With this imaging system, spatial and spectral signals of the orb-weaving spider, Nephila pilipes, were recorded, and color contrast images corresponding to the bee's spatial resolution were constructed and analyzed. The result not only confirmed that the color markings of N. pilipes are of high chromatic contrast to the eyes of a bee, but it also indicated that the spatial arrangement of these markings resemble flower patterns which may attract bees to visit them. Thus, it is likely that the orb-weaving spider (N. pilipes) deploys a similar strategy to that of the Australian crab spider (Thomisus spectabilis) to exploit the bee's pre-existing preference for

  10. Branching Ratios for The Radiometric Calibration of EUNIS-2012

    NASA Technical Reports Server (NTRS)

    Daw, Adrian N.; Bhatia, A. K.; Rabin, Douglas M.

    2012-01-01

    The Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument is a two-channel imaging spectrograph that observes the solar corona and transition region with high spectral resolution and a rapid cadence made possible by unprecedented sensitivity. The upcoming flight will incorporate a new wavelength channel covering the range 524-630 Angstroms, the previously-flown 300-370 Angstroms channel, and the first flight demonstration of cooled active pixel sensor (APS) arrays. The new 524-630 Angstrom channel incorporates a Toroidal Varied Line Space (TVLS) grating coated with B4C/Ir, providing broad spectral coverage and a wide temperature range of 0.025 to 10 MK. Absolute radiometric calibration of the two channels is being performed using a hollow cathode discharge lamp and NIST-calibrated AXUV-100G photodiode. Laboratory observations of He I 584 Angstroms and He II 304 Angstroms provide absolute radiometric calibrations of the two channels at those two respective wavelengths by using the AXUV photodiode as a transfer standard. The spectral responsivity is being determined by observing line pairs with a common upper state in the spectra of Ne I-III and Ar II-III. Calculations of A-values for the observed branching ratios are in progress.

  11. Earth Observing-1 Advanced Land Imager: Radiometric Response Calibration

    NASA Technical Reports Server (NTRS)

    Mendenhall, J. A.; Lencioni, D. E.; Evans, J. B.

    2000-01-01

    The Advanced Land Imager (ALI) is one of three instruments to be flown on the first Earth Observing mission (EO-1) under NASA's New Millennium Program (NMP). ALI contains a number of innovative features, including a wide field of view optical design, compact multispectral focal plane arrays, non-cryogenic HgCdTe detectors for the short wave infrared bands, and silicon carbide optics. This document outlines the techniques adopted during ground calibration of the radiometric response of the Advanced Land Imager. Results from system level measurements of the instrument response, signal-to-noise ratio, saturation radiance, and dynamic range for all detectors of every spectral band are also presented.

  12. Evaluation of S190A radiometric exposure test data

    NASA Technical Reports Server (NTRS)

    Lockwood, H. E.; Goodding, R. A.

    1974-01-01

    The S190A preflight radiometric exposure test data generated as part of preflight and system test of KM-002 Sequence 29 on flight camera S/N 002 was analyzed. The analysis was to determine camera system transmission using available data which included: (1) films exposed to a calibrated light source subject; (2) filter transmission data; (3) calibrated light source data; (4) density vs. log10 exposure curves for the films; and (5) spectral sensitometric data for the films. The procedure used is outlined, and includes the data and a transmission matrix as a function of field position for nine measured points on each station-film-filter-aperture-shutter speed combination.

  13. Cropland measurement using Thematic Mapper data and radiometric model

    NASA Technical Reports Server (NTRS)

    Lyon, John G.; Khuwaiter, I. H. S.

    1989-01-01

    To halt erosion and desertification, it is necessary to quantify resources that are affected. Necessary information includes inventory of croplands and desert areas as they change over time. Several studies indicate the value of remote sensor data as input to inventories. In this study, the radiometric modeling of spectral characteristics of soil and vegetation provides the theoretical basis for the remote sensing approach. Use of Landsat Thematic Mapper images allows measurement of croplands in Saudi Arabia, demonstrating the capability of the approach. The inventory techniques and remote sensing approach presented are potentially useful in developing countries.

  14. Cropland measurement using Thematic Mapper data and radiometric model

    NASA Technical Reports Server (NTRS)

    Lyon, John G.; Khuwaiter, I. H. S.

    1989-01-01

    To halt erosion and desertification, it is necessary to quantify resources that are affected. Necessary information includes inventory of croplands and desert areas as they change over time. Several studies indicate the value of remote sensor data as input to inventories. In this study, the radiometric modeling of spectral characteristics of soil and vegetation provides the theoretical basis for the remote sensing approach. Use of Landsat Thematic Mapper images allows measurement of croplands in Saudi Arabia, demonstrating the capability of the approach. The inventory techniques and remote sensing approach presented are potentially useful in developing countries.

  15. Spatial-spectral (space-wavenumber) correspondence relationship and Fresnel zone spectra.

    PubMed

    Han, Pin; Hsieh, Tsung-Han; Liu, Yi-Ling

    2017-03-01

    A correspondence relationship between space and wavenumber for fully spatially coherent uniform monochromatic and polychromatic light in near- and far-field diffraction is fully illustrated, and it is used to study a phenomenon called the Fresnel zone spectra, which is verified experimentally. The spectra can be filtered or manipulated by moving the detection position relative to Fresnel zone plate along the optical axis.

  16. Spatial resolving power and spectral sensitivity of the saltwater crocodile, Crocodylus porosus, and the freshwater crocodile, Crocodylus johnstoni.

    PubMed

    Nagloo, Nicolas; Collin, Shaun P; Hemmi, Jan M; Hart, Nathan S

    2016-05-01

    Crocodilians are apex amphibious predators that occupy a range of tropical habitats. In this study, we examined whether their semi-aquatic lifestyle and ambush hunting mode are reflected in specific adaptations in the peripheral visual system. Design-based stereology and microspectrophotometry were used to assess spatial resolving power and spectral sensitivity of saltwater (Crocodylus porosus) and freshwater crocodiles (Crocodylus johnstoni). Both species possess a foveal streak that spans the naso-temporal axis and mediates high spatial acuity across the central visual field. The saltwater crocodile and freshwater crocodile have a peak spatial resolving power of 8.8 and 8.0 cycles deg(-1), respectively. Measurement of the outer segment dimensions and spectral absorbance revealed five distinct photoreceptor types consisting of three single cones, one twin cone and a rod. The three single cones (saltwater/freshwater crocodile) are violet (424/426 nm λmax), green (502/510 nm λmax) and red (546/554 nm λmax) sensitive, indicating the potential for trichromatic colour vision. The visual pigments of both members of the twin cones have the same λmax as the red-sensitive single cone and the rod has a λmax at 503/510 nm (saltwater/freshwater). The λmax values of all types of visual pigment occur at longer wavelengths in the freshwater crocodile compared with the saltwater crocodile. Given that there is a greater abundance of long wavelength light in freshwater compared with a saltwater environment, the photoreceptors would be more effective at detecting light in their respective habitats. This suggests that the visual systems of both species are adapted to the photic conditions of their respective ecological niche. © 2016. Published by The Company of Biologists Ltd.

  17. Changes in the Radiometric Sensitivity of SeaWiFS

    NASA Technical Reports Server (NTRS)

    McClain, Charles R.; Barnes, Robert A.; Eplee, Robert E., Jr.; Patt, Frederick S.

    1998-01-01

    We report on the lunar and solar measurements used to determine the changes in the radiometric sensitivity of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Radiometric sensitivity is defined as the output from the instrument (or from one of the instrument bands) per unit spectral radiance at the instrument's input aperture. Knowledge of the long-term repeatability of the SeaWiFS measurements is crucial to maintaining the quality of the ocean scenes derived from measurements by the instrument. For SeaWiFS bands 1 through 6 (412 nm through 670 rim), the change in radiometric sensitivity is less than 0.2% for the period from November 1997 through November 1998. For band 7 (765 nm), the change is about 1.5%, and for band 8 (865 nm) about 5%. The rates of change of bands 7 and 8, which were linear with time for the first eight months of lunar measurements, are now slowing. The scatter in the data points about the trend lines in this analysis is less than 0.3% for all eight SeaWiFS bands. These results are based on monthly measurements of the moon. Daily solar measurements using an onboard diffuser show that the radiometric sensitivities of the SeaWiFS bands have changed smoothly during the time intervals between lunar measurements. Since SeaWiFS measurements have continued past November 1998, the results presented here are considered as a snapshot of the instrument performance as of that date.

  18. [On-orbit radiometric calibration accuracy of FY-3A MERSI thermal infrared channel].

    PubMed

    Xu, Na; Hu, Xiu-qing; Chen, Lin; Zhang, Yong; Hu, Ju-yang; Sun, Ling

    2014-12-01

    Accurate satellite radiance measurements are significant for data assimilations and quantitative retrieval applications. In the present paper, radiometric calibration accuracy of FungYun-3A (FY-3A) Medium Resolution Spectral Imager (MERSI) thermal infrared (TIR) channel was evaluated based on simultaneous nadir observation (SNO) intercalibration method. Hyperspectral and high-quality measurements of METOP-A/IASI were used as reference. Assessment uncertainty from intercalibration method was also investigated by examining the relation between BT bias against four main collocation factors, i. e. observation time difference, view geometric difference related to zenith angles and azimuth angles, and scene spatial homogeneity. It was indicated that the BT bias is evenly distributed across the collocation variables with no significant linear relationship in MERSI IR channel. Among the four collocation factors, the scene spatial homogeneity may be the most important factor with the uncertainty less than 2% of BT bias. Statistical analysis of monitoring biases during one and a half years indicates that the brightness temperature measured by MERSI is much warmer than that of IASI. The annual mean bias (MERSI-IASI) in 2012 is (3.18±0.34) K. Monthly averaged BT biases show a little seasonal variation character, and fluctuation range is less than 0.8 K. To further verify the reliability, our evaluation result was also compared with the synchronous experiment results at Dunhuang and Qinghai Lake sites, which showed excellent agreement. Preliminary analysis indicates that there are two reasons leading to the warm bias. One is the overestimation of blackbody emissivity, and the other is probably the incorrect spectral respond function which has shifted to window spectral. Considering the variation character of BT biases, SRF error seems to be the dominant factor.

  19. Utilizing spatial and spectral features of photoacoustic imaging for ovarian cancer detection and diagnosis

    NASA Astrophysics Data System (ADS)

    Li, Hai; Kumavor, Patrick; Salman Alqasemi, Umar; Zhu, Quing

    2015-01-01

    A composite set of ovarian tissue features extracted from photoacoustic spectral data, beam envelope, and co-registered ultrasound and photoacoustic images are used to characterize malignant and normal ovaries using logistic and support vector machine (SVM) classifiers. Normalized power spectra were calculated from the Fourier transform of the photoacoustic beamformed data, from which the spectral slopes and 0-MHz intercepts were extracted. Five features were extracted from the beam envelope and another 10 features were extracted from the photoacoustic images. These 17 features were ranked by their p-values from t-tests on which a filter type of feature selection method was used to determine the optimal feature number for final classification. A total of 169 samples from 19 ex vivo ovaries were randomly distributed into training and testing groups. Both classifiers achieved a minimum value of the mean misclassification error when the seven features with lowest p-values were selected. Using these seven features, the logistic and SVM classifiers obtained sensitivities of 96.39±3.35% and 97.82±2.26%, and specificities of 98.92±1.39% and 100%, respectively, for the training group. For the testing group, logistic and SVM classifiers achieved sensitivities of 92.71±3.55% and 92.64±3.27%, and specificities of 87.52±8.78% and 98.49±2.05%, respectively.

  20. Far-UV Spectral and Spatial Analysis from HST Observations of Europa

    NASA Astrophysics Data System (ADS)

    Becker, T. M.; Retherford, K. D.; Roth, L.; McGrath, M. A.; Saur, J.; Hendrix, A. R.; Royer, E. M.; Raut, U.

    2016-12-01

    Observations of Europa in the far-UV have revealed that the Galilean satellite lacks the strong water-ice absorption edge at 165 nm that is apparent in laboratory spectra and in the observations of nearly all regions on the icy Saturnian satellites. The reddened spectral slope measured shortward of 500 nm indicates a UV-absorbing material in the surface composition on both the leading and trailing hemispheres of Europa. We present an analysis of an extensive set of far-UV observations made with the Space Telescope Imaging Spectrograph (STIS) instrument on the Hubble Space Telescope spanning 1999 - 2015. In this data set, which covers 112-170 nm, we see no indication of the water-ice absorption edge. We report spectral differences between the leading and trailing hemispheres of Europa at these wavelengths and compare our far-UV data set with previous observations in the UV and visible. We will discuss possible explanations for the UV-absorbing component on Europa and its implications for potentially detecting relative surface ages of the satellite. The investigation also includes a study of the phase angle dependence for the reflectance of Europa and a comparison with several of the icy satellites of Saturn.

  1. Radiometric correction of LANDSAT data

    NASA Technical Reports Server (NTRS)

    Dejesusparada, N.; Kumar, R. (Principal Investigator); Cavalcanti, L. A.

    1977-01-01

    The author has identified the following significant results. The six independent sensors of the multispectral band scanner are supposed to be identical; however, in actual practice, they may have different gain settings and offset factors, which result in the effect known as stripping (black lines at regular intervals) of the imagery. A simple two parameter method to correct the gain settings and offset factors of each of the sensors with respect to one sensor, taken as reference, was developed. This method assumes: (1) the response of a detector varies linearly with the radiance of radiation received, and (2) the means, as well as the standard deviations, of a reasonably large number of pixels, in a given wavelength band, are equal for each of the detectors for the radiometrically corrected data.

  2. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    PubMed Central

    Lin, Jia-De; Wang, Tsai-Yen; Mo, Ting-Shan; Huang, Shuan-Yu; Lee, Chia-Rong

    2016-01-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. The total tuning spectral range for the cell is as broad as 165 nm and covers almost the entire visible region. Based on the gradient-pitched PSBP, a spatially tunable laser is also demonstrated in this work. The temperature sensitivity of the lasing wavelength for the laser is negatively linear and approximately −0.26 nm/°C. The two devices have a great potential for use in applications of photonic devices and displays because of their multiple advantages, such as wide-band tunability, wide operated temperature range, high stability and reliability, no issue of hysteresis, no need of external controlling sources, and not slow tuning speed (mechanically). PMID:27456475

  3. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    NASA Astrophysics Data System (ADS)

    Lin, Jia-De; Wang, Tsai-Yen; Mo, Ting-Shan; Huang, Shuan-Yu; Lee, Chia-Rong

    2016-07-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. The total tuning spectral range for the cell is as broad as 165 nm and covers almost the entire visible region. Based on the gradient-pitched PSBP, a spatially tunable laser is also demonstrated in this work. The temperature sensitivity of the lasing wavelength for the laser is negatively linear and approximately ‑0.26 nm/°C. The two devices have a great potential for use in applications of photonic devices and displays because of their multiple advantages, such as wide-band tunability, wide operated temperature range, high stability and reliability, no issue of hysteresis, no need of external controlling sources, and not slow tuning speed (mechanically).

  4. High spatial resolution three-dimensional mapping of vegetation spectral dynamics using computer vision and hobbyist unmanned aerial vehicles

    NASA Astrophysics Data System (ADS)

    Dandois, J. P.; Ellis, E. C.

    2013-12-01

    High spatial resolution three-dimensional (3D) measurements of vegetation by remote sensing are advancing ecological research and environmental management. However, substantial economic and logistical costs limit this application, especially for observing phenological dynamics in ecosystem structure and spectral traits. Here we demonstrate a new aerial remote sensing system enabling routine and inexpensive aerial 3D measurements of canopy structure and spectral attributes, with properties similar to those of LIDAR, but with RGB (red-green-blue) spectral attributes for each point, enabling high frequency observations within a single growing season. This 'Ecosynth' methodology applies photogrammetric ''Structure from Motion'' computer vision algorithms to large sets of highly overlapping low altitude (< 130 m) aerial photographs acquired using off-the-shelf digital cameras mounted on an inexpensive (< USD$4000), lightweight (< 2 kg), hobbyist-grade unmanned aerial system (UAS). Ecosynth 3D point clouds with densities of 30 - 67 points m-2 were produced using commercial computer vision software from digital photographs acquired repeatedly by UAS over three 6.25 ha (250 m x 250 m) Temperate Deciduous forest sites in Maryland USA. Ecosynth canopy height maps (CHMs) were strong predictors of field-measured tree heights (R2 0.63 to 0.84) and were highly correlated with a LIDAR CHM (R 0.87) acquired 4 days earlier, though Ecosynth-based estimates of aboveground biomass densities included significant errors (31 - 36% of field-based estimates). Repeated scanning of a 0.25 ha forested area at six different times across a 16 month period revealed ecologically significant dynamics in canopy color at different heights and a structural shift upward in canopy density, as demonstrated by changes in vertical height profiles of point density and relative RGB brightness. Changes in canopy relative greenness were highly correlated (R2 = 0.88) with MODIS NDVI time series for the same

  5. Spatial resolution dependence on spectral frequency in human speech cortex electrocorticography

    NASA Astrophysics Data System (ADS)

    Muller, Leah; Hamilton, Liberty S.; Edwards, Erik; Bouchard, Kristofer E.; Chang, Edward F.

    2016-10-01

    Objective. Electrocorticography (ECoG) has become an important tool in human neuroscience and has tremendous potential for emerging applications in neural interface technology. Electrode array design parameters are outstanding issues for both research and clinical applications, and these parameters depend critically on the nature of the neural signals to be recorded. Here, we investigate the functional spatial resolution of neural signals recorded at the human cortical surface. We empirically derive spatial spread functions to quantify the shared neural activity for each frequency band of the electrocorticogram. Approach. Five subjects with high-density (4 mm center-to-center spacing) ECoG grid implants participated in speech perception and production tasks while neural activity was recorded from the speech cortex, including superior temporal gyrus, precentral gyrus, and postcentral gyrus. The cortical surface field potential was decomposed into traditional EEG frequency bands. Signal similarity between electrode pairs for each frequency band was quantified using a Pearson correlation coefficient. Main results. The correlation of neural activity between electrode pairs was inversely related to the distance between the electrodes; this relationship was used to quantify spatial falloff functions for cortical subdomains. As expected, lower frequencies remained correlated over larger distances than higher frequencies. However, both the envelope and phase of gamma and high gamma frequencies (30-150 Hz) are largely uncorrelated (<90%) at 4 mm, the smallest spacing of the high-density arrays. Thus, ECoG arrays smaller than 4 mm have significant promise for increasing signal resolution at high frequencies, whereas less additional gain is achieved for lower frequencies. Significance. Our findings quantitatively demonstrate the dependence of ECoG spatial resolution on the neural frequency of interest. We demonstrate that this relationship is consistent across patients and

  6. The Rosetta UV imaging spectrometer ALICE: First light optical and radiometric performance results

    NASA Astrophysics Data System (ADS)

    Slater, D. C.; Stern, S. A.; A'Hearn, M. F.; Bertaux, J. L.; Feldman, P. D.; Festou, M. C.

    2000-10-01

    We describe the design, scientific objectives, and "first-light" radiometric testing results of the Rosetta/ALICE instrument. ALICE is a lightweight (2.7 kg), low-power (4 W), and low-cost imaging spectrometer optimized for cometary ultraviolet spectroscopy. ALICE, which is funded by NASA (with hardware contributions from CNES, France), will fly on the ESA Rosetta Orbiter to characterize the cometary nucleus, coma, and nucleus/coma coupling of the target comet 46P/Wirtanen. It will obtain spatially-resolved, far-UV spectra of Wirtanen's nucleus and coma in the 700-2050 Å passband with a spectral resolution of 5-10 Å for extended sources that fill the entrance slit's field- of-view. ALICE is also the UV spectrometer model for the PERSI remote sensing suite proposed for the Pluto Kuiper Express (PKE) mission. ALICE uses modern technology to achieve its low mass and low power design specifications. It employs an off-axis telescope feeding a 0.15-m normal incidence Rowland circle spectrograph with a concave (toroidal) holographic reflection grating. The imaging microchannel plate (MCP) detector utilizes dual solar-blind opaque photocathodes of KBr and CsI deposited on a cylindrically-curved (7.5-cm radius) MCP Z-stack, and a matching 2-D cylindrically-curved double delay-line readout array with a 1024 x 32 pixel array format. This array format provides a point source response that is twice that originally proposed (Δ λ 3 Å). Three data taking modes are possible: (i) histogram image mode for 2-D images, (ii) pixel list mode with periodic time hacks for temporal studies, and (iii) count rate mode for broadband photometric studies. Optical and radiometric sensitivity performance results based on subsystem tests of the flight optics, detector, and preliminary integrated system level tests of the integrated ALICE flight model are presented and discussed.

  7. A stochastic framework for downscaling processes of spatial averages based on the property of spectral multiscaling and its statistical diagnosis on spatio-temporal rainfall fields

    NASA Astrophysics Data System (ADS)

    Pavlopoulos, Harry

    2011-08-01

    Spectral multi-scaling postulates a power-law type of scaling of spectral distribution functions of stationary processes of spatial averages, over nested and geometrically similar sub-regions of the spatial parameter space of a given spatio-temporal random field. Presently a new framework is formulated for down-scaling processes of spatial averages, following naturally from the postulate of spectral multi-scaling, and key ingredients required for its implementation are described. Moreover, results from an extensive diagnostic study are presented, seeking statistical evidence supportive of spectral multi-scaling. Such evidence emerges from two sources of data. One is a 13 year long historical record of radar observations of rainfall in southeastern UK (Chenies radar), with high spatial (2 km) and temporal (5 min) resolution. The other is an ensemble of rain rate fields simulated by a spatio-temporal random pulse model fitted to the historical data. The results are consistent between historical and simulated rainfall data, indicating frequency-dependent scaling relationships interpreted as evidence of spectral multi-scaling across a range of spatial scales.

  8. Remote detection of fluid-related diagenetic mineralogical variations in the Wingate Sandstone at different spatial and spectral resolutions

    NASA Astrophysics Data System (ADS)

    Okyay, Unal; Khan, Shuhab D.

    2016-02-01

    Well-exposed eolian units of the Jurassic system on the Colorado Plateau including the Wingate Sandstone, show prominent color variations throughout southeastern Utah due to diagenetic changes that include precipitation and/or removal of iron oxide, clay, and carbonate cement. Spatially variable characteristic diagenetic changes suggest fluid-rock interactions through the sandstone. Distinctive spectral signatures of diagenetic minerals can be used to map diagenetic mineral variability and possibly fluid-flow pathways. The main objective of this work was to identify characteristic diagenetic minerals, and map their spatial variability from regional to outcrop scale in Wingate Sandstone exposures of Lisbon Valley, Utah. Laboratory reflectance spectroscopy analysis of the samples facilitated identification of diagnostic spectral characteristics of the common diagenetic minerals and their relative abundances between altered and unaltered Wingate Sandstone. Comparison of reflectance spectroscopy with satellite, airborne, and ground-based imaging spectroscopy data provided a method for mapping and evaluating spatial variations of diagenetic minerals. The Feature-oriented Principal Component Selection method was used on Advanced Spaceborne Thermal Emission and Reflection Radiometer data so as to map common mineral groups throughout the broader Wingate Sandstone exposure in the area. The Minimum Noise Fraction and Spectral Angle Mapper methods were applied on airborne HyMap and ground-based hyperspectral imaging data to identify and map mineralogical changes. The satellite and airborne data showed that out of 25.55 km2 total exposure of Wingate Sandstone in Lisbon Valley, unaltered sandstone cover 12.55 km2, and altered sandstone cover 8.90 km2 in the northwest flank and 5.09 km2 in the southern flank of the anticline. The ground-based hyperspectral data demonstrated the ability to identify and map mineral assemblages with two-dimensional lateral continuity on near

  9. A method for atmospheric correction based on the MERIS spectral and spatial variability

    NASA Astrophysics Data System (ADS)

    Béal, D.; Baret, F.; Bacour, C.; Gu, X.; Regner, P.

    Atmospheric correction is necessary to estimate the surface reflectance required within biophysical algorithms used to estimate canopy characteristics. Aerosol characterization is obviously one of the main problem in atmospheric correction because aerosol may vary rapidly with time and space. The objective of this study is to develop an autonomous aerosol correction method exploiting the information content in MERIS images. The spectral variation of the radiance signal, when enough sampled by the sensor, allows decoupling aerosol effects from that of the surface because of the very different spectral features exhibited. We thus propose to use (i) 13 over the 15 MERIS bands, (ii) the geometry of the scene and (iii) the atmospheric pressure and ozone and water vapour contents to estimate the aerosol optical thickness (AOT) assuming only continental aerosol type in this prototype algorithm. For this purpose, several dedicated neural networks were trained to retrieve aerosol AOT from the top of atmosphere signal contained in MERIS level 1B products. The training database was generated with radiative transfer model simulations, SMAC coupled to SAIL and PROSPECT. Performances demonstrate the pertinence of the method for the median of 5 neural networks, with a 0.047 Root Mean Square Error associated to the estimation of the AOT at 550nm. This induces a RMSE on the estimated top of canopy reflectance better than 0.005. In addition, assuming that the aerosol vary typically over scales of few tenths of kilometers, while the surface varies at shorter distances, allows to smooth out the AOT values for all pixels of an image using a moving window. The method was applied to actual MERIS data (more than 50 scenes) over AERONET sites for its validation with a 0.07 Root Mean Square Error associated to the estimation of the AOT. Conclusions are drawn on possible improvements of the database and of the neural network's architecture like the number of entries and the inclusion of

  10. Characterization of the Sonoran desert as a radiometric calibration target for Earth observing sensors

    USGS Publications Warehouse

    Angal, Amit; Chander, Gyanesh; Xiong, Xiaoxiong; Choi, Tae-young; Wu, Aisheng

    2011-01-01

    To provide highly accurate quantitative measurements of the Earth's surface, a comprehensive calibration and validation of the satellite sensors is required. The NASA Moderate Resolution Imaging Spectroradiometer (MODIS) Characterization Support Team, in collaboration with United States Geological Survey, Earth Resources Observation and Science Center, has previously demonstrated the use of African desert sites to monitor the long-term calibration stability of Terra MODIS and Landsat 7 (L7) Enhanced Thematic Mapper plus (ETM+). The current study focuses on evaluating the suitability of the Sonoran Desert test site for post-launch long-term radiometric calibration as well as cross-calibration purposes. Due to the lack of historical and on-going in situ ground measurements, the Sonoran Desert is not usually used for absolute calibration. An in-depth evaluation (spatial, temporal, and spectral stability) of this site using well calibrated L7 ETM+ measurements and local climatology data has been performed. The Sonoran Desert site produced spatial variability of about 3 to 5% in the reflective solar regions, and the temporal variations of the site after correction for view-geometry impacts were generally around 3%. The results demonstrate that, barring the impacts due to occasional precipitation, the Sonoran Desert site can be effectively used for cross-calibration and long-term stability monitoring of satellite sensors, thus, providing a good test site in the western hemisphere.

  11. Initial Radiometric Calibration of the AWiFS using Vicarious Calibration Techniques

    NASA Technical Reports Server (NTRS)

    Pagnutti, Mary; Thome, Kurtis; Aaron, David; Leigh, Larry

    2006-01-01

    NASA SSC maintains four ASD FieldSpec FR spectroradiometers: 1) Laboratory transfer radiometers; 2) Ground surface reflectance for V&V field collection activities. Radiometric Calibration consists of a NIST-calibrated integrating sphere which serves as a source with known spectral radiance. Spectral Calibration consists of a laser and pen lamp illumination of integrating sphere. Environmental Testing includes temperature stability tests performed in environmental chamber.

  12. Assessing the performance of multiple spectral-spatial features of a hyperspectral image for classification of urban land cover classes using support vector machines and artificial neural network

    NASA Astrophysics Data System (ADS)

    Pullanagari, Reddy; Kereszturi, Gábor; Yule, Ian J.; Ghamisi, Pedram

    2017-04-01

    Accurate and spatially detailed mapping of complex urban environments is essential for land managers. Classifying high spectral and spatial resolution hyperspectral images is a challenging task because of its data abundance and computational complexity. Approaches with a combination of spectral and spatial information in a single classification framework have attracted special attention because of their potential to improve the classification accuracy. We extracted multiple features from spectral and spatial domains of hyperspectral images and evaluated them with two supervised classification algorithms; support vector machines (SVM) and an artificial neural network. The spatial features considered are produced by a gray level co-occurrence matrix and extended multiattribute profiles. All of these features were stacked, and the most informative features were selected using a genetic algorithm-based SVM. After selecting the most informative features, the classification model was integrated with a segmentation map derived using a hidden Markov random field. We tested the proposed method on a real application of a hyperspectral image acquired from AisaFENIX and on widely used hyperspectral images. From the results, it can be concluded that the proposed framework significantly improves the results with different spectral and spatial resolutions over different instrumentation.

  13. Radiometric calibration of tempospatially modulated polarization interference imaging spectrometer.

    PubMed

    Gao, Peng; Ai, Jingjing; Zhang, Chunmin

    2016-12-10

    The tempospatially modulated polarization interference imaging spectrometer (TSMPIIS) nominated by the Ministry of Scence and Technology, takes part in the "Eleventh Five-Year National Science and Technology Exhibition." In order to improve the detecting precision of the TSMPIIS, its radiometric calibration scheme is proposed on the basis of the solar simulator, integrating sphere, monochromator, and spectroradiometer. Under the conditions of changing the exposure time and radiant brightness, the CCD linear responses for the TSMPIIS were first tested to validate the reliability of the radiometric calibration performed with a linear response model, and the linear errors were less than 0.15% and 1.15%, respectively. A novel method is put forward to calibrate the nonuniformity of CCD pixels, and the least squares method can commendably correct the uneven effect in the spatial direction. Besides, the absolute radiometric calibration establishes a corresponding relation between the dimensionless intensity output from the TSMPIIS and the target radiant brightness. The study lays the foundation for the engineering application of the TSMPIIS, such as remote sensing detection, and has an important significance for the development of our instrument and equipment technology with independent intellectual property rights.

  14. Investigation of Solar Flares Using Spectrally, Spatially, and Temporally Resolved Observations in Gamma Rays, Hard X Rays, and Microwaves

    NASA Technical Reports Server (NTRS)

    Crannell, Carol Jo; Oegerle, William (Technical Monitor)

    2003-01-01

    The high-energy components of solar flares radiate at a wide range of wavelengths. We are using spatially, spectrally, and temporally resolved hard X-ray, gamma-ray, and microwave observations of solar flares to investigate flare models and to understand the flare acceleration process. The hard X-ray and gamma-ray observations are obtained with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) spacecraft that was launched on February 5, 2002. The microwave observations are obtained with the Owens Valley Radio Observatory (OVRO), which has been dedicated to daily observations of solar flares in microwaves with a five-element interferometer since June 1992. These studies are expected to yield exciting new insights into the fundamental physics of the flare acceleration processes.

  15. Simulation of heat and mass transfer in turbulent channel flow using the spectral-element method: effect of spatial resolution

    NASA Astrophysics Data System (ADS)

    Ryzhenkov, V.; Ivashchenko, V.; Vinuesa, R.; Mullyadzhanov, R.

    2016-10-01

    We use the open-source code nek5000 to assess the accuracy of high-order spectral element large-eddy simulations (LES) of a turbulent channel flow depending on the spatial resolution compared to the direct numerical simulation (DNS). The Reynolds number Re = 6800 is considered based on the bulk velocity and half-width of the channel. The filtered governing equations are closed with the dynamic Smagorinsky model for subgrid stresses and heat flux. The results show very good agreement between LES and DNS for time-averaged velocity and temperature profiles and their fluctuations. Even the coarse LES grid which contains around 30 times less points than the DNS one provided predictions of the friction velocity within 2.0% accuracy interval.

  16. Automated mapping of impervious surfaces in urban and suburban areas: Linear spectral unmixing of high spatial resolution imagery

    NASA Astrophysics Data System (ADS)

    Yang, Jian; He, Yuhong

    2017-02-01

    Quantifying impervious surfaces in urban and suburban areas is a key step toward a sustainable urban planning and management strategy. With the availability of fine-scale remote sensing imagery, automated mapping of impervious surfaces has attracted growing attention. However, the vast majority of existing studies have selected pixel-based and object-based methods for impervious surface mapping, with few adopting sub-pixel analysis of high spatial resolution imagery. This research makes use of a vegetation-bright impervious-dark impervious linear spectral mixture model to characterize urban and suburban surface components. A WorldView-3 image acquired on May 9th, 2015 is analyzed for its potential in automated unmixing of meaningful surface materials for two urban subsets and one suburban subset in Toronto, ON, Canada. Given the wide distribution of shadows in urban areas, the linear spectral unmixing is implemented in non-shadowed and shadowed areas separately for the two urban subsets. The results indicate that the accuracy of impervious surface mapping in suburban areas reaches up to 86.99%, much higher than the accuracies in urban areas (80.03% and 79.67%). Despite its merits in mapping accuracy and automation, the application of our proposed vegetation-bright impervious-dark impervious model to map impervious surfaces is limited due to the absence of soil component. To further extend the operational transferability of our proposed method, especially for the areas where plenty of bare soils exist during urbanization or reclamation, it is still of great necessity to mask out bare soils by automated classification prior to the implementation of linear spectral unmixing.

  17. Towards Optimal Spectral and Spatial Documentation of Cultural Heritage. Cosch - AN Interdisciplinary Action in the Cost Framework

    NASA Astrophysics Data System (ADS)

    Boochs, F.; Bentkowska-Kafel, A.; Degringy, C.; Hautta-Kasari, M.; Rizvic, S.; Sitnik, R.; Tremeau, A.

    2013-07-01

    This paper introduces the aims and early activities of Colour and Space in Cultural Heritage (COSCH), an interdisciplinary European network of experts in the latest optical measuring techniques and electronic imaging applied to documentation of artefacts. COSCH is a forum open to organisations, institutions and companies interested in collaboration within the emerging field of precise spectral and spatial imaging techniques, in physical and chemical sciences applied to cultural heritage objects, as well as in research and applications to conservation and art-historical analysis of such objects. COSCH started in November 2012. Funded by COST, an intergovernmental framework for European Cooperation in Science and Technology, COSCH networking activities enable knowledge exchange and coordination of nationally-funded research on a European level with occasional contribution of experts from other countries. Funding has been made available for four years (2012-2016). Participation is open to researchers across a wide range of disciplines, including computer scientists and museum professionals, art historians and academics in heritage-related fields. COSCH is a trans-domain Action (TD1201) of the COST Domain Materials, Physics and Nanosciences (MPNS) which facilitates and promotes innovation in material science. The work of COSCH is defined in the Memorandum of Understanding between the COST Office and the Chairman of COSCH. The Memorandum is available from http://www.cost.eu/domains_actions/mpns/Actions/TD1201 alongside the latest progress report and other documents. The scientific work draws on earlier and current research of the participants and is organised around the following areas: spectral and spatial object documentation; algorithms and procedures; analysis and restoration of surfaces and objects of material culture; visualisation of cultural heritage objects and its dissemination

  18. Prevalence and spatial distribution of cystoid spaces in retinitis pigmentosa: investigation with spectral domain optical coherence tomography.

    PubMed

    Makiyama, Yukiko; Oishi, Akio; Otani, Atsushi; Ogino, Ken; Nakagawa, Satoko; Kurimoto, Masafumi; Yoshimura, Nagahisa

    2014-05-01

    To investigate the prevalence and spatial distribution of cystoid spaces (CS) in retinitis pigmentosa patients with spectral domain optical coherence tomography. A total of 529 eyes of 275 patients with retinitis pigmentosa were examined with spectral domain optical coherence tomography. The presence or absence of CS was judged for each eye. Retinal layer and outer retinal status where the CS existed were also investigated. Statistical analysis was performed using 1 eye per 1 patient. Cystoid spaces were present in 119 of 529 eyes (22.5%) of 74 of 275 patients (26.9%). There were no significant differences between the cases with and without CS except for central foveal thickness (P < 0.001). Cystoid spaces were noted in the inner nuclear layer in almost all eyes (98.6%), and outer nuclear layer/outer plexiform layer was also involved in many eyes (27.8%). Cystoid spaces were sometimes seen in ganglion cell layer (6.9%). Cystoid spaces were predominantly (78.9%) distributed in the relatively preserved retina where external limiting membrane was retained. The presence of epiretinal membrane or posterior vitreous adhesion was associated with the presence of CS (P < 0.001) but showed no relationship with the spatial location of CS (P = 1.000). The prevalence of CS in patients with retinitis pigmentosa was 26.9% and contrary to previous reports, most CS were present in inner nuclear layer. In addition, most CS were observed in relatively retained retina, which is compatible to the prevailing notion. Epiretinal membrane or posterior vitreous adhesion was also associated with the development of CS. The distribution of CS in inner and preserved retina may provide insight for the pathogenesis of CS in retinitis pigmentosa.

  19. Spectral measurements at different spatial scales in potato: relating leaf, plant and canopy nitrogen status

    NASA Astrophysics Data System (ADS)

    Jongschaap, Raymond E. E.; Booij, Remmie

    2004-09-01

    Chlorophyll contents in vegetation depend on soil nitrogen availability and on crop nitrogen uptake, which are important management factors in arable farming. Crop nitrogen uptake is important, as nitrogen is needed for chlorophyll formation, which is important for photosynthesis, i.e. the conversion of absorbed radiance into plant biomass. The objective of this study was to estimate leaf and canopy nitrogen contents by near and remote sensing observations and to link observations at leaf, plant and canopy level. A theoretical base is presented for scaling-up leaf optical properties to whole plants and crops, by linking different optical recording techniques at leaf, plant and canopy levels through the integration of vertical nitrogen distribution. Field data come from potato experiments in The Netherlands in 1997 and 1998, comprising two potato varieties: Eersteling and Bintje, receiving similar nitrogen treatments (0, 100, 200 and 300 kg N ha -1) in varying application schemes to create differences in canopy nitrogen status during the growing season. Ten standard destructive field samplings were performed to follow leaf area index and crop dry weight evolution. Samples were analysed for inorganic nitrogen and total nitrogen contents. At sampling dates, spectral measurements were taken both at leaf level and at canopy level. At leaf level, an exponential relation between SPAD-502 readings and leaf organic nitrogen contents with a high correlation factor of 0.91 was found. At canopy level, an exponential relation between canopy organic nitrogen contents and red edge position ( λrep, nm) derived from reflectance measurements was found with a good correlation of 0.82. Spectral measurements (SPAD-502) at leaf level of a few square mm were related to canopy reflectance measurements (CropScan™) of approximately 0.44 m 2. Statistical regression techniques were used to optimise theoretical vertical nitrogen profiles that allowed scaling-up leaf chlorophyll measurements

  20. Investigating the Potential of Using the Spatial and Spectral Information of Multispectral LiDAR for Object Classification

    PubMed Central

    Gong, Wei; Sun, Jia; Shi, Shuo; Yang, Jian; Du, Lin; Zhu, Bo; Song, Shalei

    2015-01-01

    The abilities of multispectral LiDAR (MSL) as a new high-potential active instrument for remote sensing have not been fully revealed. This study demonstrates the potential of using the spectral and spatial features derived from a novel MSL to discriminate surface objects. Data acquired with the MSL include distance information and the intensities of four wavelengths at 556, 670, 700, and 780 nm channels. A support vector machine was used to classify diverse objects in the experimental scene into seven types: wall, ceramic pots, Cactaceae, carton, plastic foam block, and healthy and dead leaves of E. aureum. Different features were used during classification to compare the performance of different detection systems. The spectral backscattered reflectance of one wavelength and distance represented the features from an equivalent single-wavelength LiDAR system; reflectance of the four wavelengths represented the features from an equivalent multispectral image with four bands. Results showed that the overall accuracy of using MSL data was as high as 88.7%, this value was 9.8%–39.2% higher than those obtained using a single-wavelength LiDAR, and 4.2% higher than for multispectral image. PMID:26340630

  1. Applications of UV Spatial Heterodyne Spectroscopy for High Spectral Resolution Studies of Diffuse Emission Line Sources in the Solar System

    NASA Astrophysics Data System (ADS)

    Harris, W.; Roesler, F.; Mierkiewicz, E.; Corliss, J.

    2003-05-01

    A Spatial Heterodyne Spectrometer (SHS) instrument combines high etendue and high spectral resolution in a compact package that is very effective for the study of diffuse low surface brightness emissions. SHS instruments require no telescope to achieve high sensitivity on extended sources and may be designed with fields of view exceeding 1 degree and spectral resolutions exceeding 100000. This combination makes them well suited to many solar system targets including comets, the interplanetary medium, and planetary atmospheres/coronas, using platforms from sounding rockets to remote probes. We are currently developing two variations of the SHS. The first of these is a new form of all-reflective, common-path SHS optimized for the study of FUV emission lines where transmitting optics will introduce an unacceptable attenuation of the incident beam. Secondly we are developing a multiorder variation of the SHS, where a customized high order grating is used to overlap integer orders of multiple target emission lines that can then be separated using a transform technique or with order separation filters. In this presentation we will describe the basic SHS technique, the design variations we are pursuing, and their rationale, both technical and scientific.

  2. Investigating the Potential of Using the Spatial and Spectral Information of Multispectral LiDAR for Object Classification.

    PubMed

    Gong, Wei; Sun, Jia; Shi, Shuo; Yang, Jian; Du, Lin; Zhu, Bo; Song, Shalei

    2015-09-02

    The abilities of multispectral LiDAR (MSL) as a new high-potential active instrument for remote sensing have not been fully revealed. This study demonstrates the potential of using the spectral and spatial features derived from a novel MSL to discriminate surface objects. Data acquired with the MSL include distance information and the intensities of four wavelengths at 556, 670, 700, and 780 nm channels. A support vector machine was used to classify diverse objects in the experimental scene into seven types: wall, ceramic pots, Cactaceae, carton, plastic foam block, and healthy and dead leaves of E. aureum. Different features were used during classification to compare the performance of different detection systems. The spectral backscattered reflectance of one wavelength and distance represented the features from an equivalent single-wavelength LiDAR system; reflectance of the four wavelengths represented the features from an equivalent multispectral image with four bands. Results showed that the overall accuracy of using MSL data was as high as 88.7%, this value was 9.8%-39.2% higher than those obtained using a single-wavelength LiDAR, and 4.2% higher than for multispectral image.

  3. Monitoring the spatial and temporal dynamics of the Brazilian Cerrado physiognomies with spectral vegetation indices: An assessment within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA)

    NASA Astrophysics Data System (ADS)

    Ferreira, Laerte Guimaraes, Junior

    The large extension and diversity of the Cerrado vegetative cover, the second largest biome in South America, has a strong impact on regional, and possibly global, energy, water, and carbon balances. Nevertheless, as a major farming frontier in Brazil, it is estimated that about 40% of the Cerrado land cover has already been converted into cultivated pastures, field crops, urban development, and degraded areas. Despite this aggressive pace of land conversion, there have been few investigations on the operational utilization of remote sensing data to effectively monitor and understand this biome. Within this context, and within the goals and framework of the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), we evaluated the usefulness of spectral vegetation indices (VIs), to effectively monitor the Cerrado, detect land conversions, and discriminate and assess the conditions of the major structural types of Cerrado vegetation. Using a full hydrologic year (1995) of AVHRR, local-area-coverage (LAC), data over the Cerrado, converted to normalized difference vegetation index (NDVI) and soil adjusted vegetation index (SAVI), we were able to spatially discriminate three major communities based on their phenologic patterns. These included savanna formations and pasture sites, forested areas, and agricultural crops. We also analyzed wet and dry season, aircraft-based radiometric data and a ground-based set of biophysical measurements, collected over the Brasilia National Park (BNP), the largest LBA core site in the Cerrado biome. Overall, we found the MODIS vegetation indices, which include a continuity NDVI and the new enhanced vegetation index (EVI), to provide better performance capabilities with improved dynamic ranges and contrasts in seasonal dynamics. Land cover discrimination was favored by the NDVI, while the EVI more strongly responded to the seasonal contrast of the vegetative cover. Thus, the synergistic use of the MODIS VI products will very likely

  4. BOREAS TE-18, 60-m, Radiometrically Rectified Landsat TM Imagery

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Knapp, David

    2000-01-01

    The BOREAS TE-18 team used a radiometric rectification process to produce standardized DN values for a series of Landsat TM images of the BOREAS SSA and NSA in order to compare images that were collected under different atmospheric conditions. The images for each study area were referenced to an image that had very clear atmospheric qualities. The reference image for the SSA was collected on 02-Sep-1994, while the reference image for the NSA was collected on 2 1 Jun-1995. The 23 rectified images cover the period of 07-Jul-1985 to 18-Sep-1994 in the SSA and 22-Jun-1984 to 09-Jun-1994 in the NSA. Each of the reference scenes had coincident atmospheric optical thickness measurements made by RSS-11. The radiometric rectification process is described in more detail by Hall et al. (1991). The original Landsat TM data were received from CCRS for use in the BOREAS project. Due to the nature of the radiometric rectification process and copyright issues, the full-resolution (30-m) images may not be publicly distributed. However, this spatially degraded 60-m resolution version of the images may be openly distributed and is available on the BOREAS CD-ROM series. After the radiometric rectification processing, the original data were degraded to a 60-m pixel size from the original 30-m pixel size by averaging the data over a 2- by 2-pixel window. The data are stored in binary image-format files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  5. Nuclear spatial and spectral features based evolutionary method for meningioma subtypes classification in histopathology.

    PubMed

    Fatima, Kiran; Majeed, Hammad; Irshad, Humayun

    2017-04-05

    Meningioma subtypes classification is a real-world multiclass problem from the realm of neuropathology. The major challenge in solving this problem is the inherent complexity due to high intra-class variability and low inter-class variation in tissue samples. The development of computational methods to assist pathologists in characterization of these tissue samples would have great diagnostic and prognostic value. In this article, we proposed an optimized evolutionary framework for the classification of benign meningioma into four subtypes. This framework investigates the imperative role of RGB color channels for discrimination of tumor subtypes and compute structural, statistical and spectral phenotypes. An evolutionary technique, Genetic Algorithm, in combination with Support Vector Machine is applied to tune classifier parameters and to select the best possible combination of extracted phenotypes that improved the classification accuracy (94.88%) on meningioma histology dataset, provided by the Institute of Neuropathology, Bielefeld. These statistics show that computational framework can robustly discriminate four subtypes of benign meningioma and may aid pathologists in the diagnosis and classification of these lesions.

  6. SPATIALLY AND SPECTRALLY RESOLVED OBSERVATIONS OF A ZEBRA PATTERN IN A SOLAR DECIMETRIC RADIO BURST

    SciTech Connect

    Chen Bin; Bastian, T. S.; Gary, D. E.; Jing Ju

    2011-07-20

    We present the first interferometric observation of a zebra-pattern radio burst with simultaneous high spectral ({approx}1 MHz) and high time (20 ms) resolution. The Frequency-Agile Solar Radiotelescope Subsystem Testbed (FST) and the Owens Valley Solar Array (OVSA) were used in parallel to observe the X1.5 flare on 2006 December 14. By using OVSA to calibrate the FST, the source position of the zebra pattern can be located on the solar disk. With the help of multi-wavelength observations and a nonlinear force-free field extrapolation, the zebra source is explored in relation to the magnetic field configuration. New constraints are placed on the source size and position as a function of frequency and time. We conclude that the zebra burst is consistent with a double-plasma resonance model in which the radio emission occurs in resonance layers where the upper-hybrid frequency is harmonically related to the electron cyclotron frequency in a coronal magnetic loop.

  7. Spatially and Spectrally Resolved Observations of a Zebra Pattern in a Solar Decimetric Radio Burst

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Bastian, T. S.; Gary, D. E.; Jing, Ju

    2011-07-01

    We present the first interferometric observation of a zebra-pattern radio burst with simultaneous high spectral (≈1 MHz) and high time (20 ms) resolution. The Frequency-Agile Solar Radiotelescope Subsystem Testbed (FST) and the Owens Valley Solar Array (OVSA) were used in parallel to observe the X1.5 flare on 2006 December 14. By using OVSA to calibrate the FST, the source position of the zebra pattern can be located on the solar disk. With the help of multi-wavelength observations and a nonlinear force-free field extrapolation, the zebra source is explored in relation to the magnetic field configuration. New constraints are placed on the source size and position as a function of frequency and time. We conclude that the zebra burst is consistent with a double-plasma resonance model in which the radio emission occurs in resonance layers where the upper-hybrid frequency is harmonically related to the electron cyclotron frequency in a coronal magnetic loop.

  8. Spatially and spectrally engineered spin-orbit interaction for achromatic virtual shaping.

    PubMed

    Pu, Mingbo; Zhao, Zeyu; Wang, Yanqin; Li, Xiong; Ma, Xiaoliang; Hu, Chenggang; Wang, Changtao; Huang, Cheng; Luo, Xiangang

    2015-05-11

    The geometries of objects are deterministic in electromagnetic phenomena in all aspects of our world, ranging from imaging with spherical eyes to stealth aircraft with bizarre shapes. Nevertheless, shaping the physical geometry is often undesired owing to other physical constraints such as aero- and hydro-dynamics in the stealth technology. Here we demonstrate that it is possible to change the traditional law of reflection as well as the electromagnetic characters without altering the physical shape, by utilizing the achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces. The proposal is validated by full-wave simulations and experimental characterization in optical wavelengths ranging from 600 nm to 2800 nm and microwave frequencies in 8-16 GHz, with echo reflectance less than 10% in the whole range. The virtual shaping as well as the revised law of reflection may serve as a versatile tool in many realms, including broadband and conformal camouflage and Kinoform holography, to name just a few.

  9. Spatially and spectrally engineered spin-orbit interaction for achromatic virtual shaping

    PubMed Central

    Pu, Mingbo; Zhao, Zeyu; Wang, Yanqin; Li, Xiong; Ma, Xiaoliang; Hu, Chenggang; Wang, Changtao; Huang, Cheng; Luo, Xiangang

    2015-01-01

    The geometries of objects are deterministic in electromagnetic phenomena in all aspects of our world, ranging from imaging with spherical eyes to stealth aircraft with bizarre shapes. Nevertheless, shaping the physical geometry is often undesired owing to other physical constraints such as aero- and hydro-dynamics in the stealth technology. Here we demonstrate that it is possible to change the traditional law of reflection as well as the electromagnetic characters without altering the physical shape, by utilizing the achromatic phase shift stemming from spin-orbit interaction in ultrathin space-variant and spectrally engineered metasurfaces. The proposal is validated by full-wave simulations and experimental characterization in optical wavelengths ranging from 600 nm to 2800 nm and microwave frequencies in 8-16 GHz, with echo reflectance less than 10% in the whole range. The virtual shaping as well as the revised law of reflection may serve as a versatile tool in many realms, including broadband and conformal camouflage and Kinoform holography, to name just a few. PMID:25959663

  10. Estimating high mosquito-producing rice fields using spectral and spatial data

    NASA Technical Reports Server (NTRS)

    Wood, B. L.; Beck, L. R.; Washino, R. K.; Hibbard, K. A.; Salute, J. S.

    1992-01-01

    The cultivation of irrigated rice provides ideal larval habitat for a number of anopheline vectors of malaria throughout the world. Anopheles freeborni, a potential vector of human malaria, is associated with the nearly 240,000 hectares of irrigated rice grown annually in Northern and Central California; therefore, this species can serve as a model for the study of rice field anopheline population dynamics. Analysis of field data revealed that rice fields with early season canopy development, that are located near bloodmeal sources (i.e., pastures with livestock) were more likely to produce anopheline larvae than fields with less developed canopies located further from pastures. Remote sensing reflectance measurements of early-season canopy development and geographic information system (GIS) measurements of distanes between rice fields and pastures with livestock were combined to distinguish between high and low mosquito-producing rice fields. Using spectral and distance measures in either a discriminant or Bayesian analysis, the identification of high mosquito-producing fields was made with 85 percent accuracy nearly two months before anopheline larval populations peaked. Since omission errors were also minimized by these approaches, they could provide a new basis for directing abatement techniques for the control of malaria vectors.

  11. Spectral and spatial anisotropy of the oxide growth onRu(0001)

    NASA Astrophysics Data System (ADS)

    Böttcher, A.; Starke, U.; Conrad, H.; Blume, R.; Niehus, H.; Gregoratti, L.; Kaulich, B.; Barinov, A.; Kiskinova, M.

    2002-11-01

    Scanning photoelectron spectromicroscopy has been used to study the onset and the initial stages of oxidation of Ru(0001) at three oxidation temperatures, 625, 675, and 775 K, and oxygen exposures of about 105 Langmuir. The lateral heterogeneity developed during oxide nucleation and growth and the local composition of the coexisting phases have been determined using as fingerprints the O 1s and Ru 3d spectra, thus combining chemical mapping with spectroscopy from selected features from the maps. The onset of oxide formation is characterized by the appearance of randomly distributed small islands (⩾0.5 μm) identified as germinal patches exhibiting some spectral features of bulk RuO2. The following anisotropic growth of the RuO2 phase and in particular the shape of the oxide islands shows a strong dependence on the oxidation temperature. The spectroscopic information obtained for the areas surrounding the oxide islands reveals an intermediate oxygen state characterized by distinct O 1s and Ru 3d features different from both the chemisorbed and the oxide form. It is assigned to an intermediate state acting as precursor of the oxide. The experimental data are discussed in the framework of the oxidation pathway and of core level fingerprints for the various oxygen-Ru phases suggested in recent theoretical models.

  12. Space station image captures a red tide ciliate bloom at high spectral and spatial resolution

    PubMed Central

    Dierssen, Heidi; McManus, George B.; Chlus, Adam; Qiu, Dajun; Gao, Bo-Cai; Lin, Senjie

    2015-01-01

    Mesodinium rubrum is a globally distributed nontoxic ciliate that is known to produce intense red-colored blooms using enslaved chloroplasts from its algal prey. Although frequent enough to have been observed by Darwin, blooms of M. rubrum are notoriously difficult to quantify because M. rubrum can aggregate into massive clouds of rusty-red water in a very short time due to its high growth rates and rapid swimming behavior and can disaggregate just as quickly by vertical or horizontal dispersion. A September 2012 hyperspectral image from the Hyperspectral Imager for the Coastal Ocean sensor aboard the International Space Station captured a dense red tide of M. rubrum (106 cells per liter) in surface waters of western Long Island Sound. Genetic data confirmed the identity of the chloroplast as a cryptophyte that was actively photosynthesizing. Microscopy indicated extremely high abundance of its yellow fluorescing signature pigment phycoerythrin. Spectral absorption and fluorescence features were related to ancillary photosynthetic pigments unique to this organism that cannot be observed with traditional satellites. Cell abundance was estimated at a resolution of 100 m using an algorithm based on the distinctive yellow fluorescence of phycoerythrin. Future development of hyperspectral satellites will allow for better enumeration of bloom-forming coastal plankton, the associated physical mechanisms, and contributions to marine productivity. PMID:26627232

  13. Spatial patterns of historical temperature variability: Global correlations using spectral and wavelet techniques

    SciTech Connect

    Park, J.

    1995-12-31

    In order to assess man`s impact on global climate, we need to understand natural climate variability more fully. Using 100 years of global temperature data, we have developed time-series methods that identify coherent spatio-temporal {open_quotes}modes{close_quotes} of temperature variability e.g., El Nino-Southern Oscillation (ENSO) cycles. Methods based on multiple-taper spectral analysis estimate the correlated temperature variability within narrow frequency bands. Methods based on a multiple wavelet analysis identify short-term global temperature {open_quotes}events{close_quotes} on a range of time scales. We assess the statistical significance of narrow-band and event correlations from Monte Carlo confidence limits, which are derived from stochastic variations of uncorrelated white-noise time series. Significant patterns of variability with 2.8 to 5.7 year duration exhibit the characteristic ENSO pattern: warming in the tropics, followed by temperature excursions in middle latitudes. An interdecadal mode (15-18 years) appears to represent long-term ENSO variability, an interpretation supported by the persistence of warm Pacific Ocean surface water in the decade after the large 1982-3 El Nino episode. The interdecadal mode appears to explain much of the anomalous global warmth of the 1980s. North Atlantic variability dominates quasi-biennial (2.2 years) and decadal (7-12 years) modes.

  14. Space station image captures a red tide ciliate bloom at high spectral and spatial resolution.

    PubMed

    Dierssen, Heidi; McManus, George B; Chlus, Adam; Qiu, Dajun; Gao, Bo-Cai; Lin, Senjie

    2015-12-01

    Mesodinium rubrum is a globally distributed nontoxic ciliate that is known to produce intense red-colored blooms using enslaved chloroplasts from its algal prey. Although frequent enough to have been observed by Darwin, blooms of M. rubrum are notoriously difficult to quantify because M. rubrum can aggregate into massive clouds of rusty-red water in a very short time due to its high growth rates and rapid swimming behavior and can disaggregate just as quickly by vertical or horizontal dispersion. A September 2012 hyperspectral image from the Hyperspectral Imager for the Coastal Ocean sensor aboard the International Space Station captured a dense red tide of M. rubrum (10(6) cells per liter) in surface waters of western Long Island Sound. Genetic data confirmed the identity of the chloroplast as a cryptophyte that was actively photosynthesizing. Microscopy indicated extremely high abundance of its yellow fluorescing signature pigment phycoerythrin. Spectral absorption and fluorescence features were related to ancillary photosynthetic pigments unique to this organism that cannot be observed with traditional satellites. Cell abundance was estimated at a resolution of 100 m using an algorithm based on the distinctive yellow fluorescence of phycoerythrin. Future development of hyperspectral satellites will allow for better enumeration of bloom-forming coastal plankton, the associated physical mechanisms, and contributions to marine productivity.

  15. Estimating high mosquito-producing rice fields using spectral and spatial data

    NASA Technical Reports Server (NTRS)

    Wood, B. L.; Beck, L. R.; Washino, R. K.; Hibbard, K. A.; Salute, J. S.

    1992-01-01

    The cultivation of irrigated rice provides ideal larval habitat for a number of anopheline vectors of malaria throughout the world. Anopheles freeborni, a potential vector of human malaria, is associated with the nearly 240,000 hectares of irrigated rice grown annually in Northern and Central California; therefore, this species can serve as a model for the study of rice field anopheline population dynamics. Analysis of field data revealed that rice fields with early season canopy development, that are located near bloodmeal sources (i.e., pastures with livestock) were more likely to produce anopheline larvae than fields with less developed canopies located further from pastures. Remote sensing reflectance measurements of early-season canopy development and geographic information system (GIS) measurements of distanes between rice fields and pastures with livestock were combined to distinguish between high and low mosquito-producing rice fields. Using spectral and distance measures in either a discriminant or Bayesian analysis, the identification of high mosquito-producing fields was made with 85 percent accuracy nearly two months before anopheline larval populations peaked. Since omission errors were also minimized by these approaches, they could provide a new basis for directing abatement techniques for the control of malaria vectors.

  16. Improving Spectral Results Using Row-by-Row Fourier Transform of Spatial Heterodyne Raman Spectrometer Interferogram.

    PubMed

    Barnett, Patrick D; Strange, K Alicia; Angel, S Michael

    2016-12-12

    This work describes a method of applying the Fourier transform to the two-dimensional Fizeau fringe patterns generated by the spatial heterodyne Raman spectrometer (SHRS), a dispersive interferometer, to correct the effects of certain types of optical alignment errors. In the SHRS, certain types of optical misalignments result in wavelength-dependent and wavelength-independent rotations of the fringe pattern on the detector. We describe here a simple correction technique that can be used in post-processing, by applying the Fourier transform in a row-by-row manner. This allows the user to be more forgiving of fringe alignment and allows for a reduction in the mechanical complexity of the SHRS.

  17. Radiometric Characterization of Hyperspectral Imagers using Multispectral Sensors

    NASA Technical Reports Server (NTRS)

    McCorkel, Joel; Kurt, Thome; Leisso, Nathan; Anderson, Nikolaus; Czapla-Myers, Jeff

    2009-01-01

    The Remote Sensing Group (RSG) at the University of Arizona has a long history of using ground-based test sites for the calibration of airborne and satellite based sensors. Often, ground-truth measurements at these test sites are not always successful due to weather and funding availability. Therefore, RSG has also automated ground instrument approaches and cross-calibration methods to verify the radiometric calibration of a sensor. The goal in the cross-calibration method is to transfer the calibration of a well-known sensor to that of a different sensor, This work studies the feasibility of determining the radiometric calibration of a hyperspectral imager using multispectral a imagery. The work relies on the Moderate Resolution Imaging Spectroradiometer (M0DIS) as a reference for the hyperspectral sensor Hyperion. Test sites used for comparisons are Railroad Valley in Nevada and a portion of the Libyan Desert in North Africa. Hyperion bands are compared to MODIS by band averaging Hyperion's high spectral resolution data with the relative spectral response of M0DlS. The results compare cross-calibration scenarios that differ in image acquisition coincidence, test site used for the calibration, and reference sensor. Cross-calibration results are presented that show agreement between the use of coincident and non-coincident image pairs within 2% in most brands as well as similar agreement between results that employ the different MODIS sensors as a reference.

  18. Multidimensional optical signal processing using optical coherent transient spatial-spectral holography

    NASA Astrophysics Data System (ADS)

    Anderson, Kenneth Edward

    This thesis presents analysis and experimental demonstrations of several new optical signal processing architectures that are based on optical coherent transient (OCT) technology and investigates many system design issues that must be taken into account when building such systems. OCT materials have the potential to optically process both high bandwidth (>10 GHz) and high time-bandwidth (>106) signals with the ability to potentially store huge amounts of data (up to 1000's of TB/cm3 using spatial-temporal holography. Several OCT system architectures are proposed and discussed including: raster image correlators, scanners, RF spectrum analyzers, time integrating correlators, image sequence correlators, and dynamic optical switches. In addition, some of the first experimental demonstrations of multiple channel spatial-temporal signal processing using OCT materials are shown. Novel system architectures for performing chromatic, polarization mode, and modal dispersion compensation are discussed, analyzed, and initial experimental results are shown demonstrating chromatic dispersion compensation of up to 5 mus of dispersion. A new approach for multiplexing 100's of individual DWDM channels of information down one multimode fiber is proposed and analyzed. In addition, a high bandwidth adaptive phased array beam steering system is also proposed and investigated along with experimental results showing the first demonstration of simultaneous time delay and processing of information with OCT materials. Lastly, results are presented for several stabilized lasers systems that have been built throughout the course of this research. The techniques used for stabilizing these lasers systems included optical feedback from gratings and Fabry-Perot cavities and electronic feedback techniques using Pound-Drever-Hall frequency locking.

  19. Spatial-temporal patterns of electrocorticographic spectral changes during midazolam sedation

    PubMed Central

    Nishida, Masaaki; Zestos, Maria M.; Asano, Eishi

    2015-01-01

    Objective To better understand ‘when’ and ‘where’ wideband electrophysiological signals are altered by sedation. Methods We generated animation movies showing electrocorticography (ECoG) amplitudes at eight spectral frequency bands across 1.0 to 116 Hz, every 0.1 second, on three-dimensional surface images of 10 children who underwent epilepsy surgery. We measured the onset, intensity, and variance of each band amplitude change at given nonepileptic regions separately from those at affected regions. We also determined the presence of differential ECoG changes depending on the brain anatomy. Results Within 20 seconds following injection of midazolam, beta (16–31.5 Hz) and sigma (12–15.5 Hz) activities began to be multifocally augmented with increased variance in amplitude at each site. Beta-sigma augmentation was most prominent within the association neocortex. Augmentation of low-delta activity (1.0–1.5 Hz) was relatively modest and confined to the somatosensory-motor region. Conversely, injection of midazolam induced attenuation of theta (4.0–7.5 Hz) and high-gamma (64–116 Hz) activities. Conclusions Our observations support the notion that augmentation beta-sigma and delta activities reflects cortical deactivation or inactivation, whereas theta and high-gamma activities contribute to maintenance of consciousness. The effects of midazolam on the dynamics of cortical oscillations differed across regions. Significance Sedation, at least partially, reflects a multi-local phenomenon at the cortical level rather than global brain alteration homogeneously driven by the common central control structure. PMID:26613652

  20. Spatially resolved Spitzer-IRS spectral maps of the superwind in M82

    NASA Astrophysics Data System (ADS)

    Beirão, P.; Armus, L.; Lehnert, M. D.; Guillard, P.; Heckman, T.; Draine, B.; Hollenbach, D.; Walter, F.; Sheth, K.; Smith, J. D.; Shopbell, P.; Boulanger, F.; Surace, J.; Hoopes, C.; Engelbracht, C.

    2015-08-01

    We have mapped the superwind/halo region of the nearby starburst galaxy M82 in the mid-infrared with Spitzer - IRS. The spectral regions covered include the H2 S(1)-S(3), [Ne II], [Ne III] emission lines and polycyclic aromatic hydrocarbon (PAH) features. We estimate the total warm H2 mass and the kinetic energy of the outflowing warm molecular gas to be between Mwarm ˜ 5 and 17 × 106 M⊙ and EK ˜ 6 and 20 × 1053 erg. Using the ratios of the 6.2, 7.7 and 11.3 μm PAH features in the IRS spectra, we are able to estimate the average size and ionization state of the small grains in the superwind. There are large variations in the PAH flux ratios throughout the outflow. The 11.3/7.7 and the 6.2/7.7 PAH ratios both vary by more than a factor of 5 across the wind region. The northern part of the wind has a significant population of PAH's with smaller 6.2/7.7 ratios than either the starburst disc or the southern wind, indicating that on average, PAH emitters are larger and more ionized. The warm molecular gas to PAH flux ratios (H2/PAH) are enhanced in the outflow by factors of 10-100 as compared to the starburst disc. This enhancement in the H2/PAH ratio does not seem to follow the ionization of the atomic gas (as measured with the [Ne III]/[Ne II] line flux ratio) in the outflow. This suggests that much of the warm H2 in the outflow is excited by shocks. The observed H2 line intensities can be reproduced with low-velocity shocks (v < 40 km s-1) driven into moderately dense molecular gas (102 < nH < 104 cm-3) entrained in the outflow.

  1. The Circumstellar Environment of Rigel Probed at High Spatial and Spectral Resolution

    NASA Astrophysics Data System (ADS)

    Kaufer, A.; Chesneau, O.; Stahl, O.; Colvinter, C.; Spang, A.; Dessart, L.; Prinja, R.; Chini, R.

    2012-12-01

    The presence of highly structured circumstellar environments in late B- and early A-type supergiants is well established through extensive spectroscopic, photometric, and polarimetric time series observations. The circumstellar structures are located within a few stellar radii in the transition zone from the stellar photosphere to the inner wind region of the expanding envelopes of the stars. The physical mechanisms that generate the observed circumstellar structures remain subject of debate. Coupling of stellar surface structures into the inner wind regions combined with rotational modulation is generally favoured with the surface structure being results of multi-mode non-radial pulsation patterns or complex magnetic fields structures. However, little observational evidence is available to narrow down the underlying mechanisms. Optical and near-IR interferometry at high spectral resolution has high potential to shed new light on the circumstellar environments of massive supergiants. We present first results from spectro-interferometric studies of the prototypical late-B supergiant Rigel (β Orionis, B8 Ia). Rigel has for the first time been monitored over several rotational cycles with the AMBER 3-beam combiner instrument at the VLTI in 2006-2007 and 2009-2010. The observations targeted the photosphere- and wind-sensitive Brγ line at a resolving power of R=12 000. The analysis of the measured interferometric visibilities provides constraints on the extension of the line-forming region in photosphere and wind; the observed variability of the differential phases across the line profile gives indications on the dynamics and the geometry of the circumstellar structures of Rigel. A possible link between high-velocity absorptions (HVA) and the observed S-shaped signals in the differential phases is discussed.

  2. Saturation-recovery metabolic-exchange rate imaging with hyperpolarized [1-13C] pyruvate using spectral-spatial excitation.

    PubMed

    Schulte, Rolf F; Sperl, Jonathan I; Weidl, Eliane; Menzel, Marion I; Janich, Martin A; Khegai, Oleksandr; Durst, Markus; Ardenkjaer-Larsen, Jan Henrik; Glaser, Steffen J; Haase, Axel; Schwaiger, Markus; Wiesinger, Florian

    2013-05-01

    Within the last decade hyperpolarized [1-13C] pyruvate chemical-shift imaging has demonstrated impressive potential for metabolic MR imaging for a wide range of applications in oncology, cardiology, and neurology. In this work, a highly efficient pulse sequence is described for time-resolved, multislice chemical shift imaging of the injected substrate and obtained downstream metabolites. Using spectral-spatial excitation in combination with single-shot spiral data acquisition, the overall encoding is evenly distributed between excitation and signal reception, allowing the encoding of one full two-dimensional metabolite image per excitation. The signal-to-noise ratio can be flexibly adjusted and optimized using lower flip angles for the pyruvate substrate and larger ones for the downstream metabolites. Selectively adjusting the excitation of the down-stream metabolites to 90° leads to a so-called "saturation-recovery" scheme with the detected signal content being determined by forward conversion of the available pyruvate. In case of repetitive excitations, the polarization is preserved using smaller flip angles for pyruvate. Metabolic exchange rates are determined spatially resolved from the metabolite images using a simplified two-site exchange model. This novel contrast is an important step toward more quantitative metabolic imaging. Goal of this work was to derive, analyze, and implement this "saturation-recovery metabolic exchange rate imaging" and demonstrate its capabilities in four rats bearing subcutaneous tumors.

  3. Numerical Modeling of Hohlraum Radiation Conditions: Spatial and Spectral Variations due to Sample Position, Beam Pointing, and Hohlraum Geometry

    SciTech Connect

    Cohen, D H; Landen, O L; MacFarlane, J J

    2005-01-25

    View-factor simulations are presented of the spatially varying radiation conditions inside double-ended gold hohlraums and single-ended gold hohlraums (''halfraums'') used in inertial confinement fusion (ICF) and high energy density (HED) physics experiments [J. Lindl, Phys. Plasmas 11, 339 (2004); M. D. Rosen, Phys. Plasmas 3, 1803 (1996)]. It is shown that in many circumstances, the common assumption that the hohlraum ''drive'' can be characterized by a single temperature is too simplistic. Specifically, the radiation conditions seen by an experimental package can differ significantly from the wall reemission measured through diagnostic holes or laser entrance holes (LEHs) by absolutely calibrated detectors. Furthermore, even in situations where the radiation temperature is roughly the same for diagnostics and experimental packages, or for packages at different locations, the spectral energy distributions can vary significantly, due to the differing fractions of reemitting wall, laser hot spots, and LEHs seen from different locations. We find that the spatial variation of temperature, and especially the differences between what diagnostics looking in the LEH measure vs. the radiation temperature on wall-mounted experimental packages, is generally greater for double-ended hohlraums than it is for halfraums. View-factor simulations can also be used to explore experimental variables (halfraum length and geometry, sample position, and beam pointing) that can be adjusted in order to, for example, maximize the radiation flux onto a sample, or other package. In this vein, simulations of hohlraums and halfraums with LEH shields are also presented.

  4. Numerical modeling of Hohlraum radiation conditions: Spatial and spectral variations due to sample position, beam pointing, and Hohlraum geometry

    NASA Astrophysics Data System (ADS)

    Cohen, David H.; Landen, Otto L.; MacFarlane, Joseph J.

    2005-12-01

    View-factor simulations are presented of the spatially varying radiation conditions inside double-ended gold Hohlraums and single-ended gold Hohlraums ("halfraums") used in inertial confinement fusion and high-energy density physics experiments [J. Lindl, Phys. Plasmas 11, 339 (2004); M. D. Rosen, Phys. Plasmas 3, 1803 (1996)]. It is shown that in many circumstances, the common assumption that the Hohlraum "drive" can be characterized by a single temperature is too simplistic. Specifically, the radiation conditions seen by an experimental package can differ significantly from the wall reemission measured through diagnostic holes or laser entrance holes (LEHs) by absolutely calibrated detectors. Furthermore, even in situations where the radiation temperature is roughly the same for diagnostics and experimental packages, or for packages at different locations, the spectral energy distributions can vary significantly, due to the differing fractions of reemitting wall, laser hot spots, and LEHs seen from different locations. We find that the spatial variation of temperature and especially the differences between what diagnostics looking in the LEH measure versus the radiation temperature on wall-mounted experimental packages are generally greater for double-ended Hohlraums than for halfraums. View-factor simulations can also be used to explore experimental variables (halfraum length and geometry, sample position, and beam pointing) that can be adjusted in order to, for example, maximize the radiation flux onto a sample, or other package. In this vein, simulations of Hohlraums and halfraums with LEH shields are also presented.

  5. Spatially and spectrally resolved particle swarm optimization for precise optical property estimation using diffuse-reflectance spectroscopy.

    PubMed

    Kholodtsova, Maria N; Daul, Christian; Loschenov, Victor B; Blondel, Walter C P M

    2016-06-13

    This paper presents a new approach to estimate optical properties (absorption and scattering coefficients µa and µs) of biological tissues from spatially-resolved spectroscopy measurements. A Particle Swarm Optimization (PSO)-based algorithm was implemented and firstly modified to deal with spatial and spectral resolutions of the data, and to solve the corresponding inverse problem. Secondly, the optimization was improved by fitting exponential decays to the two best points among all clusters of the "particles" randomly distributed all over the parameter space (µs, µa) of possible solutions. The consequent acceleration of all the groups of particles to the "best" curve leads to significant error decrease in the optical property estimation. The study analyzes the estimated optical property error as a function of the various PSO parameter combinations, and several performance criteria such as the cost-function error and the number of iterations in the algorithms proposed. The final one led to error values between ground truth and estimated values of µs and µa less than 6%.

  6. Dynamic virtual optical network embedding in spectral and spatial domains over elastic optical networks with multicore fibers

    NASA Astrophysics Data System (ADS)

    Zhu, Ruijie; Zhao, Yongli; Yang, Hui; Tan, Yuanlong; Chen, Haoran; Zhang, Jie; Jue, Jason P.

    2016-08-01

    Network virtualization can eradicate the ossification of the infrastructure and stimulate innovation of new network architectures and applications. Elastic optical networks (EONs) are ideal substrate networks for provisioning flexible virtual optical network (VON) services. However, as network traffic continues to increase exponentially, the capacity of EONs will reach the physical limitation soon. To further increase network flexibility and capacity, the concept of EONs is extended into the spatial domain. How to map the VON onto substrate networks by thoroughly using the spectral and spatial resources is extremely important. This process is called VON embedding (VONE).Considering the two kinds of resources at the same time during the embedding process, we propose two VONE algorithms, the adjacent link embedding algorithm (ALEA) and the remote link embedding algorithm (RLEA). First, we introduce a model to solve the VONE problem. Then we design the embedding ability measurement of network elements. Based on the network elements' embedding ability, two VONE algorithms were proposed. Simulation results show that the proposed VONE algorithms could achieve better performance than the baseline algorithm in terms of blocking probability and revenue-to-cost ratio.

  7. LAI estimation in a Mediterranean grassland by in situ radiometric measurements and MODIS satellite data

    NASA Astrophysics Data System (ADS)

    Balzarolo, M.; Arriga, N.; Papale, D.

    2009-04-01

    Leaf Area Index (LAI) is one of a key variables in studying and understanding biogeochemical cycle mechanisms and ecosystem functionalities and, then, one of a main inputs for ecological modeling. Leaf area surface is related to the main interactions between leaves and the atmosphere as water interception, radiation extinction, energy, mass and gas exchange. Therefore LAI reduction, consequently the loss of productivity, is expression of any physiological and biochemical change of plant status due for example to summer water stress in Mediterranean areas. A good knowledge of seasonal trend and spatial variability of LAI can helps not only modelers but also local farmer to manage grasslands in a sustainable way (grazing, harvesting). In situ LAI measurements are often limited to relatively small areas whit a small number of samplings that can be sporadic, destructive and time-consuming. Nowadays an interesting alternative to estimate LAI is provided by a large variety of radiometric sensors (ground, airborne and satellite based) whit several spatial, temporal and spectral resolutions. However, few studies shown the effect of different radiometers set-up on VIs-LAI relationships that are also differently sensible to different ranges of LAI, management and to which method is used for LAI measurements. In this work, we analyzed the relations between several spectral vegetation indexes (VIs) and LAI for the Mediterranean grassland of Amplero, in the Abruzzo Region, Italy. In situ measurements were carried out in 2005 and 2006. Contemporaneously to destructive LAI measurements, radiometric measurements over the grass herbage were made by two different radiometric sensors: by hyperspectral Hand Held ASD spettroradiometer (HYS) field samplings and by broad band measurements (BNR) of incoming and outgoing global (shortwave) solar radiation components and of incident and reflected photosintetically active radiation (PAR). In addition we included in this analysis VIs

  8. Radiometric correction and equalization of satellite digital data

    NASA Technical Reports Server (NTRS)

    Algazi, V. R.; Ford, G. E.; Kazakoff, J. A.

    1979-01-01

    Satellite digital data from Landsat and NOAA satellites is often marred by striping or streaking errors due to variations in the response of the radiometric sensors. In this paper, we discuss the equalization of the digital data as a preprocessing step, prior to image enhancement or automatic classification. The methods described make use of statistics of the data itself to generate nonlinear or linear memory-less equalization algorithms. These algorithms, by contrast to multidimensional filtering, do not result in a loss of spatial resolution. Examples of applications to Landsat and NOAA-3 thermal infrared data are given and illustrated.

  9. Extended- and Point-Source Radiometric Program

    DTIC Science & Technology

    1962-08-08

    Radiometric Measurements of Cs1 37 Sources Made with NaI Detector. . 60 6.2 Aerial Radiometric Measurements of Co 60 Sources Made with Bioplastic ...Hanford aircraft consisted of an NaI scintillator, bioplastic scintillator, and a 40-liter ionization chamber. The aircraft employed was a twin-engine...supply, amplifier, and count rate, was transistorized portable equipment designed and fabricated at Hanford. The bioplastic instrument consisted of a 5

  10. Joint spatial-spectral feature space clustering for speech activity detection from ECoG signals.

    PubMed

    Kanas, Vasileios G; Mporas, Iosif; Benz, Heather L; Sgarbas, Kyriakos N; Bezerianos, Anastasios; Crone, Nathan E

    2014-04-01

    Brain-machine interfaces for speech restoration have been extensively studied for more than two decades. The success of such a system will depend in part on selecting the best brain recording sites and signal features corresponding to speech production. The purpose of this study was to detect speech activity automatically from electrocorticographic signals based on joint spatial-frequency clustering of the ECoG feature space. For this study, the ECoG signals were recorded while a subject performed two different syllable repetition tasks. We found that the optimal frequency resolution to detect speech activity from ECoG signals was 8 Hz, achieving 98.8% accuracy by employing support vector machines as a classifier. We also defined the cortical areas that held the most information about the discrimination of speech and nonspeech time intervals. Additionally, the results shed light on the distinct cortical areas associated with the two syllables repetition tasks and may contribute to the development of portable ECoG-based communication.

  11. A Spatial-Spectral Approach for Visualization of Vegetation Stress Resulting from Pipeline Leakage

    PubMed Central

    van der Werff, Harald; van der Meijde, Mark; Jansma, Fokke; van der Meer, Freek; Groothuis, Gert Jan

    2008-01-01

    Hydrocarbon leakage into the environment has large economic and environmental impact. Traditional methods for investigating seepages and their resulting pollution, such as drilling, are destructive, time consuming and expensive. Remote sensing is an efficient tool that offers a non-destructive investigation method. Optical remote sensing has been extensively tested for exploration of onshore hydrocarbon reservoirs and detection of hydrocarbons at the Earth's surface. In this research, we investigate indirect manifestations of pipeline leakage by way of visualizing vegetation anomalies in airborne hyperspectral imagery. Agricultural land-use causes a heterogeneous landcover; variation in red edge position between fields was much larger than infield red edge position variation that could be related to hydrocarbon pollution. A moving and growing kernel procedure was developed to normalzie red edge values relative to values of neighbouring pixels to enhance pollution related anomalies in the image. Comparison of the spatial distribution of anomalies with geochemical data obtained by drilling showed that 8 out of 10 polluted sites were predicted correctly while 2 out of 30 sites that were predicted clean were actually polluted. PMID:27879905

  12. A Spatial-Spectral Approach for Visualization of Vegetation Stress Resulting from Pipeline Leakage.

    PubMed

    Van derWerff, Harald; Van der Meijde, Mark; Jansma, Fokke; Van der Meer, Freek; Groothuis, Gert Jan

    2008-06-04

    Hydrocarbon leakage into the environment has large economic and environmental impact. Traditional methods for investigating seepages and their resulting pollution, such as drilling, are destructive, time consuming and expensive. Remote sensing is an efficient tool that offers a non-destructive investigation method. Optical remote sensing has been extensively tested for exploration of onshore hydrocarbon reservoirs and detection of hydrocarbons at the Earth's surface. In this research, we investigate indirect manifestations of pipeline leakage by way of visualizing vegetation anomalies in airborne hyperspectral imagery. Agricultural land-use causes a heterogeneous landcover; variation in red edge position between fields was much larger than infield red edge position variation that could be related to hydrocarbon pollution. A moving and growing kernel procedure was developed to normalzie red edge values relative to values of neighbouring pixels to enhance pollution related anomalies in the image. Comparison of the spatial distribution of anomalies with geochemical data obtained by drilling showed that 8 out of 10 polluted sites were predicted correctly while 2 out of 30 sites that were predicted clean were actually polluted.

  13. Spatial and temporal age-related spectral alterations in benign human breast tissue

    NASA Astrophysics Data System (ADS)

    Theophilou, Georgios; Fogarty, Simon W.; Trevisan, Júlio; Strong, Rebecca J.; Heys, Kelly A.; Patel, Imran I.; Stringfellow, Helen F.; Martin-Hirsch, Pierre L.; Martin, Francis L.

    2016-02-01

    Epidemiological evidenc