Note: This page contains sample records for the topic image cloud patterns from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Exploration Activity: Global Cloud Patterns  

NSDL National Science Digital Library

In this activity, students characterize some global patterns of deep, cold-topped clouds visible on global infrared satellite images. They will apply these characterizations to answer questions about local and global patterns of precipitation. The questions concern what clouds are and how they form, atmospheric cooling, rising air, precipitation, and the use of remote satellite imagery to see precipitation-producing clouds and storms. They will also create animated global infrared satellite images and answer some questions concerning them.

Dempsey, Dave

2005-03-10

2

Detailed Cloud Patterns in Martian Northern Hemisphere  

NASA Technical Reports Server (NTRS)

Cold and cloudy mornings; cool, hazy afternoons. High winds aloft and weather fronts moving slowly to the east. It is winter in the Martian northern hemisphere. One of the many reasons to study Mars is that, at times, its weather is very 'Earth-like.' At this time of the Martian year, clouds are abundant, especially in the morning and especially in the high northern latitudes. Clouds and fogs are also observed in low-lying areas farther to the south, in some lowlands they are as far south as the equator.

The above color composite images, obtained by Mars Global Surveyor's camera on June 4, 1998, illustrate this Martian 'weather report.' Most of the thick, white clouds seen here occur north of latitude 35oN (roughly equivalent to Albuquerque NM, Memphis TN, and Charlotte, NC). Fog (seen as bright orange because it is lighter than the ground but some of the ground is still visible) occupies the lowest portions of the Kasei Valles outflow channel around 30oN and at 25oN.

Several different types of cloud features are seen. The repetitious, wash-board pattern of parallel lines are 'gravity wave clouds'. These commonly form, in the lee--downwind side-- of topographic features such as mountain ranges (on Earth) or crater rims (on Mars), under very specific atmospheric conditions (low temperatures, high humidity, and high wind speeds). In this area, the wave clouds are lower in the atmosphere than some of the other clouds. These other clouds show attributes reflecting more the regional weather pattern, occasionally showing the characteristic 'slash' shape (southwest to northeast) of a weather front. These clouds probably contain mostly crystals of water ice but, depending on the temperature at high altitude (and more likely closer to the pole), some could also contain frozen carbon dioxide ('dry ice').

MOC images 34501 (the red wide angle image) and 34502 (the blue wide angle image) were obtained on Mars Global Surveyor's 345th orbit about the planet. The pictures were taken around 5: 34 p.m. PDT on June 4, 1998. Winter in the northern hemisphere began in mid-February, 1998, and continues to mid-July, 1998.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1998-01-01

3

Determine precipitation rates from visible and infrared satellite images of clouds by pattern recognition technique. Progress Report, 1 Jul. 1985 - 31 Mar. 1987 Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

A more advanced cloud pattern analysis algorithm was subsequently developed to take the shape and brightness of the various clouds into account in a manner that is more consistent with the human analyst's perception of GOES cloud imagery. The results of that classification scheme were compared with precipitation probabilities observed from ships of opportunity off the U.S. east coast to derive empirical regressions between cloud types and precipitation probability. The cloud morphology was then quantitatively and objectively used to map precipitation probabilities during two winter months during which severe cold air outbreaks were observed over the northwest Atlantic. Precipitation probabilities associated with various cloud types are summarized. Maps of precipitation probability derived from the cloud morphology analysis program for two months and the precipitation probability derived from thirty years of ship observation were observed.

Weinman, James A.; Garan, Louis

1987-01-01

4

Identifying Cloud computing usage patterns  

Microsoft Academic Search

The current end-users who are developing Cloud-based applications are struggling with multiple solutions for application programming interfaces (APIs) coming from different providers. This fact is partially a consequence of the focus of these APIs on the service provider expectations not on the end-user requirements. In the design of a generic API for Cloud application development, the first step should be

Dana Petcu

2010-01-01

5

Cloud patterns as seen from the Apollo 7 spacecraft  

NASA Technical Reports Server (NTRS)

Remarkable cloud patterns as seen from the Apollo 7 spacecraft during its 34th revolution of the earth. Note break in two adjacent decks of strato-cumulus cloud formations. Sea can be seen through holes in clouds.

1968-01-01

6

Biomedical image analysis and processing in clouds  

NASA Astrophysics Data System (ADS)

Cloud-based Image Analysis and Processing Toolbox project runs on the Australian National eResearch Collaboration Tools and Resources (NeCTAR) cloud infrastructure and allows access to biomedical image processing and analysis services to researchers via remotely accessible user interfaces. By providing user-friendly access to cloud computing resources and new workflow-based interfaces, our solution enables researchers to carry out various challenging image analysis and reconstruction tasks. Several case studies will be presented during the conference.

Bednarz, Tomasz; Szul, Piotr; Arzhaeva, Yulia; Wang, Dadong; Burdett, Neil; Khassapov, Alex; Chen, Shiping; Vallotton, Pascal; Lagerstrom, Ryan; Gureyev, Tim; Taylor, John

2013-10-01

7

Pattern recognition of satellite cloud imagery for improved weather prediction  

NASA Technical Reports Server (NTRS)

The major accomplishment was the successful development of a method for extracting time derivative information from geostationary meteorological satellite imagery. This research is a proof-of-concept study which demonstrates the feasibility of using pattern recognition techniques and a statistical cloud classification method to estimate time rate of change of large-scale meteorological fields from remote sensing data. The cloud classification methodology is based on typical shape function analysis of parameter sets characterizing the cloud fields. The three specific technical objectives, all of which were successfully achieved, are as follows: develop and test a cloud classification technique based on pattern recognition methods, suitable for the analysis of visible and infrared geostationary satellite VISSR imagery; develop and test a methodology for intercomparing successive images using the cloud classification technique, so as to obtain estimates of the time rate of change of meteorological fields; and implement this technique in a testbed system incorporating an interactive graphics terminal to determine the feasibility of extracting time derivative information suitable for comparison with numerical weather prediction products.

Gautier, Catherine; Somerville, Richard C. J.; Volfson, Leonid B.

1986-01-01

8

Tapering Clouds and Their Classification Due Mainly to the Surrounding Cloud Pattern in the Gms Imagery.  

National Technical Information Service (NTIS)

Active convective clouds developed into an elongated triangular pattern is called Tapering Cloud (later referred to as TC) owing to the cloud shape in the satellite imagery. TC is closely associated with severe weather, such as heavy rain, tornados, and s...

H. Itoh T. Asoh M. Sakurada

1992-01-01

9

Usage Patterns to Provision for Scientific Experimentation in Clouds  

Microsoft Academic Search

Driven by the need to provision resources on demand, scientists are turning to commercial and research test-bed Cloud computing resources to run their scientific experiments. Job scheduling on cloud computing resources, unlike earlier platforms, is a balance between throughput and cost of executions. Within this context, we posit that usage patterns can improve the job execution, because these patterns allow

Eran Chinthaka Withana; Beth Plale

2010-01-01

10

Global patterns of cloud optical thickness variation with temperature  

NASA Technical Reports Server (NTRS)

The International Satellite Cloud Climatology Project dataset is used to correlate variations of cloud optical thickness and cloud temperature in today's atmosphere. The analysis focuses on low clouds in order to limit the importance of changes in cloud vertical extent, particle size, and water phase. Coherent patterns of change are observed on several time and space scales. On the planetary scale, clouds in colder, higher latitudes are found to be optically thicker than clouds in warmer, lower latitudes. On the seasonal scale, winter clouds are, for the most part, optically thicker than summer clouds. The logarithmic derivative of cloud optical thickness with temperature is used to describe the sign and magnitude of the optical thickness-temperature correlation. The seasonal, latitudinal, and day-to-day variations of this relation are examined for Northern Hemisphere clouds in 1984. In cold continental clouds, optical thickness increases with temperature, consistent with the temperature variation of the adiabatic cloud water content. In warm continental and in almost all maritime clouds, however, optical thickness decreases with temperature.

Tselioudis, George; Rossow, William B.; Rind, David

1992-01-01

11

Global patterns of cloud optical thickness variation with temperature  

NASA Technical Reports Server (NTRS)

A global cloud climatology dataset is used to study patterns of cloud optical thickness variation with temperature. The data, which cover the period from July 1983 through June 1995, contain detailed information on the distribution of cloud radiative properties and their diurnal and seasonal variations, as well as information on the vertical distribution of temperature and humidity in the troposphere. For cold low clouds over land, the temperature coefficient of change in optical thickness has a value of about 0.04, which is similar to that deduced from Soviet aircraft observations and derived from thermodynamic considerations for the change of cloud liquid water with temperature. It is suggested that, in this cold-temperature range, cloud optical thickness variations are dominated by changes in the liquid water content of the cloud and that the liquid water content changes in accordance with the thermodynamic theory.

Tselioudis, George; Rind, David; Rossow, William B.

1990-01-01

12

Research on removing cloud from optical images  

NASA Astrophysics Data System (ADS)

This paper proposes a novel algorithm for distinguishing scenery information from cloud noise in the low-level and high-level detail coefficients using the wavelet decomposition. Also this paper shows approximate coefficients only containing the scenery information, and high-level detail coefficients mainly including the cloud noise and the partial scenery information. Usually cloud is brighter than the scene illumination. Therefore the appropriate brightness threshold is setup for processing high-level detail coefficients aimed at the elimination of cloud noise. Simultaneously to remove the residual cloud at the low frequency component and improve the clarity of the scenery image, the paper further decomposes the detail coefficients based on the frequency. For example, the low-level detail coefficients are decomposed further once or twice by wavelet packets. So we can remove remaining cloud decomposed effectively at the low frequency, and through assigning the appropriate weight to the detail coefficient, achieve the goal for enhancing scenery information and improving the image clarity. Considering influence of the parameter changes on the algorithm performance, we use the entropy as the criterion for choosing the optimal parameters step by step. We have demonstrated that this algorithm using the entropy as criterion is feasible. The experimental results are superior to homomorphism filtering and the Retinex algorithm in many aspects.

Zhu, Xifang; Wu, Feng

2011-11-01

13

Cloud Patterns in Toronto, Ontario, Canada  

NSDL National Science Digital Library

This lesson is designed to help students gain knowledge in graphing a microset of data, then using the graphs to investigate trends in cloud coverage over a given locale. Students are provided content-related activities to enhance background knowledge in cloud types, and then are provided detailed instructions on how to download data from the MY NASA DATA Live Access Server (LAS) and to use Excel to graph the data. The graphs are then used to explore trends in cloud coverage over Toronto, Ontario, Canada for a given time period. The lesson provides detailed procedure, related links and sample graphs, follow-up questions and extensions, and Teacher Notes.

2010-03-14

14

Spatial and Temporal Patterns of Aerosol-Cloud Interactions  

NASA Astrophysics Data System (ADS)

This study determines the spatial and temporal distribution of regions with frequent aerosol-cloud interactions (aci) and identifies their meteorological determinants based on CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) and ECMWF (European Centre for Medium-Range Weather Forecasts) data products. Atmospheric aerosols influence the microphysical structure of clouds, while both also respond to meteorological conditions. The potential radiative adjustments to changes in a cloud system associated with aerosol-cloud interactions are grouped and termed as effective radiative forcing due to aerosol-cloud interactions (ERFaci). It is difficult to distinguish, to what extent radiative forcing and precipitation patterns of clouds are a result of cloud feedbacks to aerosols or the existing meteorological conditions. A complete understanding of aerosol-cloud-meteorology interactions is crucial as the uncertainty range of ERFaci in climate change modeling could be significantly reduced. In the present study it is suggested that presence of hydrated aerosols is an implication for aci. Knowledge of their vertical and horizontal distribution and frequency over the globe would be important for understanding ERFaci. To identify regions with aerosol-cloud transitions the CAD score (cloud-aerosol discrimination) of the CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization) instrument on the CALIPSO satellite is used. It separates aerosols and clouds according to the probability distribution functions of 5 parameters (attenuated backscatter, total color ratio, volume depolarization ratio, altitude and latitude) and assigns the likelihood of cloud or aerosol presence. This parameter is used to calculate relative frequencies of aci on a global scale from 2006 to 2013.

Fuchs, Julia; Cermak, Jan

2014-05-01

15

Male pattern baldness (image)  

MedlinePLUS

Male pattern baldness is a sex-linked characteristic that is passed from mother to child. A man can more accurately predict his chances of developing male pattern baldness by observing his mother's father than by ...

16

Cloud Ozone Dust Imager (CODI), Volume 1.  

National Technical Information Service (NTIS)

The Cloud Ozone Dust Imager (CODI) is proposed to investigate the current climatic balance of the Mars atmosphere, with particular emphasis on the important but poorly understood roles which dust and water ice aerosols play in this balance. The large atmo...

R. T. Clancy P. Dusenbery M. Wolff P. James M. Allen J. Goguen R. Kahn R. Gladstone J. Murphy

1995-01-01

17

Optimized absorption imaging of mesoscopic atomic clouds  

NASA Astrophysics Data System (ADS)

We report on the optimization of high-intensity absorption imaging for small Bose-Einstein condensates. The imaging calibration exploits the linear scaling of the quantum projection noise with the mean number of atoms for a coherent spin state. After optimization for atomic clouds containing up to 300 atoms, we find an atom number resolution of atoms, mainly limited by photon shot noise and radiation pressure.

Muessel, Wolfgang; Strobel, Helmut; Joos, Maxime; Nicklas, Eike; Stroescu, Ion; Tomkovi?, Ji?í; Hume, David B.; Oberthaler, Markus K.

2013-10-01

18

Recognition methods on cloud amount, movement of clouds, and rain clouds for rainfall prediction using whole sky images  

NASA Astrophysics Data System (ADS)

The final target of our research is to develop a system for forecasting local concentrated heavy rain, such as guerrilla rainstorms, by using whole sky images taken on the ground. To construct this system, this paper proposes the following recognition methods: cloud amount, movement of clouds, and rain clouds. The experimental results show that red/blue (R/B) values are efficient for measuring the cloud amount. However, using the gravity of images and the difference among time-sequenced images is insufficient to recognize the movement of clouds and does not correlate well with the R/B values and rain.

Fujinuma, Kazuma; Arai, Masayuki

2014-04-01

19

CloudSat Image of Tropical Thunderstorms Over Africa  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Figure 1

CloudSat image of a horizontal cross-section of tropical clouds and thunderstorms over east Africa. The red colors are indicative of highly reflective particles such as water (rain) or ice crystals, which the blue indicates thinner clouds (such as cirrus). The flat green/blue lines across the bottom represent the ground signal. The vertical scale on the CloudS at Cloud Profiling Radar image is approximately 30 kilometers (19 miles). The brown line below the image indicates the relative elevation of the land surface. The inset image shows the CloudSat track relative to a Moderate Resolution Imaging Spectroradiometer (MODIS) visible image taken at nearly the same time.

2006-01-01

20

Clouds  

NSDL National Science Digital Library

First, the Project Atmosphere Canada offers a module to educate primary and secondary students about cloud formation and characteristics (1). The website outlines key points and offers a more in-depth discussion of water vapor, cloud formation, convection, air motion, severe weather, and more. The second website, by Scholastic, supplies many pdf documents of activities and lesson plans for all types of weather phenomena including clouds (2). Students can learn about condensation, discover what makes up a cloud, and find a key identifying the cloud types. Next, USA Today offers an online tutorial of the differing characteristics of clouds (3). Users can learn about Mammatus clouds, contrails, cloud seeding, and other cloud-related topics. At the fourth website, visitors can view meteorologist Dan Satterfield's amazing cloud photographs (4). Educators may find useful materials to supplement their lectures. Next, NASA's Climate and Radiation Branch furnishes "information on the fantastic variety of cloud forms and structures, and their implications for climate" (5). While the website is still being constructed, users can find useful information about the Bounded Cascades Fractal Cloud model, animations, and definitions of inhomogeneous cloud terminology. The sixth website, created by the National Center for Atmospheric Research and the University Corporation for Atmospheric Research, addresses how clouds impact our lives, how they cause chaos, and how they form (6). The enlightening descriptions are packed with colorful images and short quizzes. Next, The Australian Government's Bureau of Meteorology describes the useful of clouds as an indicator of weather conditions (7). After learning how moist air can form clouds, individuals can view images of the ten most common cloud types. Lastly, Enchanted Learning offers a table of the cloud types with their abbreviation, appearance, composition, and altitude along with explanations of cloud formation and the atmosphere (8). Educators can find simple activities dealing with cloud types and the water cycle.

21

A cloud-based medical image repository  

NASA Astrophysics Data System (ADS)

Many widely used digital medical image collections have been established but these are generally used as raw data sources without related image analysis toolsets. Providing associated functionality to allow specific types of operations to be performed on these images has proved beneficial in some cases (e.g. brain image registration and atlases). However, toolset development to provide generic image analysis functions on medical images has tended to be ad hoc, with Open Source options proliferating (e.g. ITK). Our Automated Medical Image Collection Annotation (AMICA) system is both an image repository, to which the research community can contribute image datasets, and a search/retrieval system that uses automated image annotation. AMICA was designed for the Windows Azure platform to leverage the flexibility and scalability of the cloud. It is intended that AMICA will expand beyond its initial pilot implementation (for brain CT, MR images) to accommodate a wide range of modalities and anatomical regions. This initiative aims to contribute to advances in clinical research by permitting a broader use and reuse of medical image data than is currently attainable. For example, cohort studies for cases with particular physiological or phenotypical profiles will be able to source and include enough cases to provide high statistical power, allowing more individualised risk factors to be assessed and thus allowing screening and staging processes to be optimised. Also, education, training and credentialing of clinicians in image interpretation, will be more effective because it will be possible to select instances of images with specific visual aspects, or correspond to types of cases where reading performance improvement is desirable.

Maeder, Anthony J.; Planitz, Birgit M.; El Rifai, Diaa

2012-02-01

22

MISR Stereo Imaging Distinguishes Smoke from Cloud  

NASA Technical Reports Server (NTRS)

These views of western Alaska were acquired by MISR on June 25, 2000 during Terra orbit 2775. The images cover an area of about 150 kilometers x 225 kilometers, and have been oriented with north to the left. The left image is from the vertical-viewing (nadir) camera, whereas the right image is a stereo 'anaglyph' that combines data from the forward-viewing 45-degree and 60-degree cameras. This image appears three-dimensional when viewed through red/blue glasses with the red filter over the left eye. It may help to darken the room lights when viewing the image on a computer screen.

The Yukon River is seen wending its way from upper left to lower right. A forest fire in the Kaiyuh Mountains produced the long smoke plume that originates below and to the right of image center. In the nadir view, the high cirrus clouds at the top of the image and the smoke plume are similar in appearance, and the lack of vertical information makes them hard to differentiate. Viewing the righthand image with stereo glasses, on the other hand, demonstrates that the scene consists of several vertically-stratified layers, including the surface terrain, the smoke, some scattered cumulus clouds, and streaks of high, thin cirrus. This added dimensionality is one of the ways MISR data helps scientists identify and classify various components of terrestrial scenes.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

2000-01-01

23

Capturing and analyzing wheelchair maneuvering patterns with mobile cloud computing.  

PubMed

Power wheelchairs have been widely used to provide independent mobility to people with disabilities. Despite great advancements in power wheelchair technology, research shows that wheelchair related accidents occur frequently. To ensure safe maneuverability, capturing wheelchair maneuvering patterns is fundamental to enable other research, such as safe robotic assistance for wheelchair users. In this study, we propose to record, store, and analyze wheelchair maneuvering data by means of mobile cloud computing. Specifically, the accelerometer and gyroscope sensors in smart phones are used to record wheelchair maneuvering data in real-time. Then, the recorded data are periodically transmitted to the cloud for storage and analysis. The analyzed results are then made available to various types of users, such as mobile phone users, traditional desktop users, etc. The combination of mobile computing and cloud computing leverages the advantages of both techniques and extends the smart phone's capabilities of computing and data storage via the Internet. We performed a case study to implement the mobile cloud computing framework using Android smart phones and Google App Engine, a popular cloud computing platform. Experimental results demonstrated the feasibility of the proposed mobile cloud computing framework. PMID:24110214

Fu, Jicheng; Hao, Wei; White, Travis; Yan, Yuqing; Jones, Maria; Jan, Yih-Kuen

2013-01-01

24

Cloud Imagers Offer New Details on Earth's Health  

NASA Technical Reports Server (NTRS)

A stunning red sunset or purple sunrise is an aesthetic treat with a scientific explanation: The colors are a direct result of the absorption or reflectance of solar radiation by atmospheric aerosols, minute particles (either solid or liquid) in the Earth s atmosphere that occur both naturally and because of human activity. At the beginning or end of the day, the Sun s rays travel farther through the atmosphere to reach an observer s eyes and more green and yellow light is scattered, making the Sun appear red. Sunset and sunrise are especially colorful when the concentration of atmospheric particles is high. This ability of aerosols to absorb and reflect sunlight is not just pretty; it also determines the amount of radiation and heat that reaches the Earth s surface, and can profoundly affect climate. In the atmosphere, aerosols are also important as nuclei for the condensation of water droplets and ice crystals. Clouds with fewer aerosols cannot form as many water droplets (called cloud particles), and consequently, do not scatter light well. In this case, more sunlight reaches the Earth s surface. When aerosol levels in clouds are high, however, more nucleation points can form small liquid water droplets. These smaller cloud particles can reflect up to 90 percent of visible radiation to space, keeping the heat from ever reaching Earth s surface. The tendency for these particles to absorb or reflect the Sun s energy - called extinction by astronomers - depends on a number of factors, including chemical composition and the humidity and temperature in the surrounding air; because cloud particles are so small, they are affected quickly by minute changes in the atmosphere. Because of this sensitivity, atmospheric scientists study cloud particles to anticipate patterns and shifts in climate. Until recently, NASA s study of atmospheric aerosols and cloud particles has been focused primarily on satellite images, which, while granting large-scale atmospheric analysis, limited scientists ability to acquire detailed information about individual particles. Now, experiments with specialized equipment can be flown on standard jets, making it possible for researchers to monitor and more accurately anticipate changes in Earth s atmosphere and weather patterns.

2009-01-01

25

Pattern Recognition and Image Processing  

Microsoft Academic Search

Extensive research and development has taken place over the last 20 years in the areas of pattern recognition and image processing. Areas to which these disciplines have been applied include business (e. g., character recognition), medicine (diagnosis, abnormality detection), automation (robot vision), military intelligence, communications (data compression, speech recognition), and many others. This paper presents a very brief survey of

King-sun Fu; Azriel Rosenfeld

1976-01-01

26

Cloud base height survey based on stereo image  

NASA Astrophysics Data System (ADS)

Cloud observation is an important factor for weather application and change of cloud base height plays a vital role in development of future weather system. Aim at requirement of cloud observation, a method on survey of cloud base height (CBH) is proposed based on stereo image. The main contents include image match and calculation of CBH which makes use of forward intersection of photogrammetry. It overcomes discontinuity, strong subjectivity and qualitative analysis of traditional eye observation. By application of National Day's weather safeguard, it tests that method of stereo imaging surveying is a way of direct measurement with better precision and is possible in technology also.

Li, Guosheng; Lin, Zongjian; Ma, Shuqing; Zhi, Xiaodong

2011-04-01

27

Statistics of Optical Radiation Patterns of Lightning on the Upper Cloud Surface  

NASA Astrophysics Data System (ADS)

The optical radiation emitted by lightning in the clouds appears as a diffuse optical pattern on the upper surface of the cloud. This signal is used for satellite based lightning observation. The paper presents a statistical analysis of the radiation pattern based on the 13 years observation data of the Lightning Imaging Sensor (LIS) on board of the TRMM. The study uses the event and group data of LIS. Despite the coarse spatial sampling of of LIS (~7km) the huge amount of data allows for a statistical sub-sampling of the radiance distribution inside the pattern. The statistical analysis includes the empirical frequency distribution of the overall geometrical shapes and sizes as well as the radiation distribution inside the pattern. Additionally the dependence of the empirical distribution on geographic location and local time and season is studied. The statistical results are compared against ground based observation of lightning mapping systems and numerical simulations of the scattering process in the cloud. The established statistics of optical pattern are to be applied in proxy data generation for the future lightning detection instrument on the next generation geostationary satellites (MTG). The projection of the radiation pattern on the geostationary view can be used to demonstrate the distortions in dependence on the off-nadir angle.

Finke, U.

2012-12-01

28

Martian Cloud Modeling using NIR Spectral Images  

NASA Astrophysics Data System (ADS)

In the near-infrared (NIR), disentangling surface and aerosol spectral features is a difficult, iterative process. In order to be able to use radiative transfer to model clouds you need to know the surface reflection characteristics; but to get the surface reflection, you need to be able to subtract off the atmospheric spectral contribution. One way to attempt to solve this is to "simply" create a monolithic system with a large number of parameters - one for each surface component, each aerosol species, and each gas constituent. Such a multi-dimensional space is no doubt complex with large difficulties in solution uniqueness. Using ground-based NIR spectral images acquired over several oppositions from the NASA IRTF, we have been able to show that a principle components analysis is able to find two surface components without any a priori inputs [1, 2]. Further work has shown that these surface spectral components are fairly uniform across all seasons [3, 4]. Additionally, we have been able to create a radiative transfer modeling system that was previously used to calculate aphelion cloud optical depths using only the 3 ?m spectral region [5]. In this presentation I will present preliminary results from combining the radiative transfer with the recovered surface spectral signatures as inputs to measure martian cloud optical depths in the NIR. This work was supported by grants from the NASA Mars Data Analysis and the NSF-RUI programs. References: [1] Klassen, D. R. and Bell III, J. F. (2001) BAAS 33, 1069. [2] Klassen, D. R., Wark, T. J., Cugliotta, C. G. (2005) BAAS, 37, 693. [3] Klassen, D. R. and Bell III, J. F. (2003) BAAS, 35, 936. [4] Klassen, D. R. and Bell III, J. F. (2007) in preparation. [5] Klassen, D. R. and Bell III, J. F. (2002) BAAS, 34, 865.

Klassen, David R.

2007-10-01

29

Cloud level winds from the Venus Express Monitoring Camera imaging  

NASA Astrophysics Data System (ADS)

Six years of continuous monitoring of Venus by European Space Agency's Venus Express orbiter provides an opportunity to study dynamics of the atmosphere our neighbor planet. Venus Monitoring Camera (VMC) on-board the orbiter has acquired the longest and the most complete so far set of ultra violet images of Venus. These images enable a study the cloud level circulation by tracking motion of the cloud features. The highly elliptical polar orbit of Venus Express provides optimal conditions for observations of the Southern hemisphere at varying spatial resolution. Out of the 2300 orbits of Venus Express over which the images used in the study cover about 10 Venus years. Out of these, we tracked cloud features in images obtained in 127 orbits by a manual cloud tracking technique and by a digital correlation method in 576 orbits. Total number of wind vectors derived in this work is 45,600 for the manual tracking and 391,600 for the digital method. This allowed us to determine the mean circulation, its long-term and diurnal trends, orbit-to-orbit variations and periodicities. We also present the first results of tracking features in the VMC near-IR images. In low latitudes the mean zonal wind at cloud tops (67 ± 2 km following: Rossow, W.B., Del Genio, A.T., Eichler, T. [1990]. J. Atmos. Sci. 47, 2053-2084) is about 90 m/s with a maximum of about 100 m/s at 40-50°S. Poleward of 50°S the average zonal wind speed decreases with latitude. The corresponding atmospheric rotation period at cloud tops has a maximum of about 5 days at equator, decreases to approximately 3 days in middle latitudes and stays almost constant poleward from 50°S. The mean poleward meridional wind slowly increases from zero value at the equator to about 10 m/s at 50°S and then decreases to zero at the pole. The error of an individual measurement is 7.5-30 m/s. Wind speeds of 70-80 m/s were derived from near-IR images at low latitudes. The VMC observations indicate a long term trend for the zonal wind speed at low latitudes to increase from 85 m/s in the beginning of the mission to 110 m/s by the middle of 2012. VMC UV observations also showed significant short term variations of the mean flow. The velocity difference between consecutive orbits in the region of mid-latitude jet could reach 30 m/s that likely indicates vacillation of the mean flow between jet-like regime and quasi-solid body rotation at mid-latitudes. Fourier analysis revealed periodicities in the zonal circulation at low latitudes. Within the equatorial region, up to 35°S, the zonal wind show an oscillation with a period of 4.1-5 days (4.83 days on average) that is close to the super-rotation period at the equator. The wave amplitude is 4-17 m/s and decreases with latitude, a feature of the Kelvin wave. The VMC observations showed a clear diurnal signature. A minimum in the zonal speed was found close to the noon (11-14 h) and maxima in the morning (8-9 h) and in the evening (16-17 h). The meridional component peaks in the early afternoon (13-15 h) at around 50°S latitude. The minimum of the meridional component is located at low latitudes in the morning (8-11 h). The horizontal divergence of the mean cloud motions associated with the diurnal pattern suggests upwelling motions in the morning at low latitudes and downwelling flow in the afternoon in the cold collar region.

Khatuntsev, I. V.; Patsaeva, M. V.; Titov, D. V.; Ignatiev, N. I.; Turin, A. V.; Limaye, S. S.; Markiewicz, W. J.; Almeida, M.; Roatsch, Th.; Moissl, R.

2013-09-01

30

Concentric gravity waves in polar mesospheric clouds from the Cloud Imaging and Particle Size experiment  

NASA Astrophysics Data System (ADS)

concentric atmospheric gravity wave (AGW) events have been identified in Polar Mesospheric Cloud (PMC) images of the summer mesopause region (~82-84 km) made by the Cloud Imaging and Particle Size (CIPS) instrument on board the Aeronomy of Ice in the Mesosphere satellite during the Northern Hemisphere 2007 and 2009 PMC seasons. The AGWs modulate the PMC albedo, ice water content, and particle size, creating concentric ring patterns. On only one occasion (13 July 2007), the concentric AGWs in PMCs were aligned with AGWs with similar shapes observed in 4.3 µm radiance in the lower stratosphere, as measured by Atmospheric Infrared Sounder (AIRS). Coincident AIRS and Infrared Atmospheric Sounding Interferometer nadir measurements of 8.1 µm radiance reveal a region of deep convection in the troposphere close to the estimated centers of the AGWs in the stratosphere, strongly suggesting that convection is the wave source. The AGWs in CIPS on 13 July 2007 were ~1000 km away from the observed deep convection. Three other concentric AGWs in PMCs were 500-1000 km away from deep convection in the troposphere, while no convection was observed related to the wave on 29 July 2009. We perform a 2-D ray tracing study for the AGW event on 13 July 2007. The calculated propagation distance is much shorter than the distance between the AGWs in PMCs and the observed convection. The 2-D ray tracing study indicates that the AGWs in PMCs and in the stratosphere are probably excited by different tropospheric convective systems.

Yue, Jia; Thurairajah, Brentha; Hoffmann, Lars; Alexander, Joan; Chandran, Amal; Taylor, Michael J.; Russell, James M.; Randall, Cora E.; Bailey, Scott M.

2014-05-01

31

Radiometric cloud imaging with an uncooled microbolometer thermal infrared camera.  

PubMed

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. PMID:19498585

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

2005-07-25

32

Data and image fusion for geometrical cloud characterization  

SciTech Connect

Clouds have a strong influence on the Earth`s climate and therefore on climate change. An important step in improving the accuracy of models that predict global climate change, general circulation models, is improving the parameterization of clouds and cloud-radiation interactions. Improvements in the next generation models will likely include the effect of cloud geometry on the cloud-radiation parameterizations. We have developed and report here methods for characterizing the geometrical features and three-dimensional properties of clouds that could be of significant value in developing these new parameterizations. We developed and report here a means of generating and imaging synthetic clouds which we used to test our characterization algorithms; a method for using Taylor`s hypotheses to infer spatial averages from temporal averages of cloud properties; a computer method for automatically classifying cloud types in an image; and a method for producing numerical three-dimensional renderings of cloud fields based on the fusion of ground-based and satellite images together with meteorological data.

Thorne, L.R.; Buch, K.A.; Sun, Chen-Hui; Diegert, C.

1997-04-01

33

Cloud Detection Method Based on Feature Extraction in Remote Sensing Images  

NASA Astrophysics Data System (ADS)

In remote sensing images, the existence of the clouds has a great impact on the image quality and subsequent image processing, as the images covered with clouds contain little useful information. Therefore, the detection and recognition of clouds is one of the major problems in the application of remote sensing images. Present there are two categories of method to cloud detection. One is setting spectrum thresholds based on the characteristics of the clouds to distinguish them. However, the instability and uncertainty of the practical clouds makes this kind of method complexity and weak adaptability. The other method adopts the features in the images to identify the clouds. Since there will be significant overlaps in some features of the clouds and grounds, the detection result is highly dependent on the effectiveness of the features. This paper presented a cloud detection method based on feature extraction for remote sensing images. At first, find out effective features through training pattern, the features are selected from gray, frequency and texture domains. The different features in the three domains of the training samples are calculated. Through the result of statistical analysis of all the features, the useful features are picked up to form a feature set. In concrete, the set includes three feature vectors, respectively, the gray feature vector constituted of average gray, variance, first-order difference, entropy and histogram, the frequency feature vector constituted of DCT high frequency coefficient and wavelet high frequency coefficient, and the texture feature vector constituted of the hybrid entropy and difference of the gray-gradient co-occurrence matrix and the image fractal dimension. Secondly, a thumbnail will be obtained by down sampling the original image and its features of gray, frequency and texture are computed. Last but not least, the cloud region will be judged by the comparison between the actual feature values and the thresholds determined by the sample training process. Experimental results show that the clouds and ground objects can be separated efficiently, and our method can implement rapid clouds detection and cloudiness calculation.

Changhui, Y.; Yuan, Y.; Minjing, M.; Menglu, Z.

2013-05-01

34

Operational Cloud-Motion Winds from Meteosat Infrared Images  

Microsoft Academic Search

The displacement of clouds in successive satellite images reflects the atmospheric circulation at various scales. The main application of the satellite-derived cloud-motion vectors is their use as winds in the data analysis for numerical weather prediction. At low latitudes in particular they constitute an indispensible data source for numerical weather prediction.This paper describes the operational method of deriving cloud-motion winds

Johannes Schmetz; Kenneth Holmlund; Joel Hoffman; Bernard Strauss; Brian Mason; Volker Gaertner; Arno Koch; Leo van de Berg

1993-01-01

35

Clouds  

NSDL National Science Digital Library

In this scenario-based, problem-based learning (PBL) activity, students investigate cloud formation, cloud classification, and the role of clouds in heating and cooling the Earth; how to interpret TRMM (Tropical Rainfall Measuring Mission) images and data; and the role clouds play in the Earthâs radiant budget and climate. Students assume the role of weather interns in a state climatology office and assist a frustrated student in a homework assignment. Learning is supported by a cloud in a bottle and an ice-albedo demonstration, a three-day cloud monitoring outdoor activity, and student journal assignments. The hands-on activities require two 2-liter soda bottles, an infrared heat lamp, and two thermometers. The resource includes a teacher's guide, questions and answer key, assessment rubric, glossary, and an appendix with information supporting PBL in the classroom.

36

Mesopause Horizontal wind estimates based on AIM CIPS polar mesospheric cloud pattern matching  

NASA Astrophysics Data System (ADS)

A cloud pattern matching approach is used to estimate horizontal winds in the mesopause region using Polar Mesospheric Cloud (PMC) albedo data measured by the Cloud Imaging and Particle Size instrument on the AIM satellite. Measurements for all 15 orbits per day throughout July 2007 are used to achieve statistical significance. For each orbit, eighteen out of the twenty-seven scenes are used for the pattern matching operation. Some scenes at the lower latitudes are not included because there is barely any cloud coverage for these scenes. The frame-size chosen is about 12 degrees in longitude and 3 degrees in latitude. There is no strict criterion in choosing the frame size since PMCs are widespread in the polar region and most local patterns do not have a clearly defined boundary. The frame moves at a step of 1/6th of the frame size in both the longitudinal and latitudinal directions to achieve as many 'snap-shots' as possible. A 70% correlation is used as a criterion to define an acceptable match between two patterns at two time frames; in this case the time difference is about 3.6 minutes that spans every 5 'bowtie' scenes. A 70% criterion appears weak if the chosen pattern is expected to act like a tracer. It is known that PMC brightness varies rapidly with a changing temperature and water vapor environment or changing nucleation conditions, especially on smaller spatial scales; therefore PMC patterns are not ideal tracers. Nevertheless, within a short time span such as 3.6 minutes a 70% correlation is sufficient to identify two cloud patterns that come from the same source region, although the two patterns may exhibit a significant difference in the actual brightness. Analysis of a large number of matched cloud patterns indicates that over the 3.6-minute time span about 70% of the patterns remain in the same locations. Given the 25-km2 horizontal resolution of CIPS data, this suggests that the overall magnitude of horizontal wind at PMC altitudes (~80-87 km) in the polar summer cannot exceed 25 m/s. In other words, the wind detection resolution is no better than 25 m/s. There are about 10% of cases in which it appears that an easterly prevails, with a peak value at about 80-100m/s. In another 5% of cases a westerly appears to prevail. The remaining 15% cases are related to either invalid cloud features with poor background correction or the situation in which the matching occurs at the corners of the bowties. The AIM CIPS cloud pattern matching results overall suggest that higher wind speed (25-200 m/s) can be reached occasionally, while in a majority of cases the wind advection caused albedo change is much smaller than the in-situ albedo change. However, we must note that this analysis was a feasibility study and the short period analyzed may not be representative of the winds over a seasonal time scale or the multiple-year average.

Rong, P.; Yue, J.; Russell, J. M.; Gong, J.; Wu, D. L.; Randall, C. E.

2013-12-01

37

A method for modelling IR images of sky and clouds  

NASA Astrophysics Data System (ADS)

Thermal radiation of objects is often used as its discriminative feature by the systems of automatic target recognition (ATR). In such case to develop effective detection algorithms it is essential to know radiation characteristics not only of the detected objects but also its surroundings. The paper presents a method of numerical modelling of clouds radiation in infrared spectral range. The experimental data for the modelling were collected taking into consideration characteristic temperature profiles of the clouds and sky, for particular seasons of the year and meteorological conditions occurring in Poland. Virtual thermal images of sky and clouds were then generated by the specially developed IR Sky software. The images generated by means of this software were analyzed, having in view influence of radiation features of sky and clouds on a thermodetection process. High consistency of computer-generated images with the registered thermal images has been obtained.

Dulski, R.; Sosnowski, T.; Polakowski, H.

2011-03-01

38

Image to Point Cloud Method of 3D-MODELING  

NASA Astrophysics Data System (ADS)

This article describes the method of constructing 3D models of objects (buildings, monuments) based on digital images and a point cloud obtained by terrestrial laser scanner. The first step is the automated determination of exterior orientation parameters of digital image. We have to find the corresponding points of the image and point cloud to provide this operation. Before the corresponding points searching quasi image of point cloud is generated. After that SIFT algorithm is applied to quasi image and real image. SIFT algorithm allows to find corresponding points. Exterior orientation parameters of image are calculated from corresponding points. The second step is construction of the vector object model. Vectorization is performed by operator of PC in an interactive mode using single image. Spatial coordinates of the model are calculated automatically by cloud points. In addition, there is automatic edge detection with interactive editing available. Edge detection is performed on point cloud and on image with subsequent identification of correct edges. Experimental studies of the method have demonstrated its efficiency in case of building facade modeling.

Chibunichev, A. G.; Galakhov, V. P.

2012-07-01

39

Algorithms for Moderate Resolution Imaging Spectroradiometer cloud-free image compositing  

NASA Astrophysics Data System (ADS)

The presence of clouds is the biggest obstacle in the investigation of land cover, and many techniques have been developed to detect clouds. However, few indicators have been proposed for the detection of cloud-free conditions. To address this, we propose two indicators for use in compositing 8-day cloud-free images: the B ratio is the ratio of the band 1 reflectance to the band 7 reflectance of Terra surface reflectance images (MOD09GA), and saturation refers to the color saturation of these images. Here, we describe the principles underlying these two indicators and analyze their characteristics for vegetation, water, urban, and nonvegetation pixels under cloud-free, cloud shadow, and cloudy conditions using MOD09GA from October 16 to 23, 2007, in North China (sample A) and using data published by the U.S. Geological Survey (USGS). We found that the B ratio and saturation are suitable for extracting cloud-free pixels over land and water, respectively; therefore, we combined these two indicators to develop a single-unified model. In particular, our results demonstrate that the pixels exhibiting the lowest B ratios should be adopted as cloud-free pixels over land when the value of B for land surfaces is between 0 and 1, and the surface reflectance of Moderate Resolution Imaging Spectroradiometer band 1 is less than 0.3. Otherwise, the pixels exhibiting the greatest saturation values should be adopted. We used our model to composite cloud-free images for two additional regions in China: the Tarim basin (sample B) from October 2 to 9, 2012, and the coastal areas of southeastern China (sample C) from April 15 to 23, 2013. We compared the cloud-free images of these regions with the 8-day surface reflectance product (MOD09A1) with respect to clouds, cloud shadow, and cirrus clouds, and we found that our proposed cloud-free image compositing approach can accurately eliminate both clouds and cirrus clouds. Specifically, the percentage of residual cloud pixels in sample C was found to be less than that in MOD09A1. Moreover, in the cloud-free images obtained using our newly developed method, cloud-free pixels are typically associated with greater sensor zenith angles and smaller scatter angles than those in MOD09A1. However, our method retains some limitations. In particular, 9.68, 33.22, and 33.00% of cloud-shadow pixels remain in the cloud-free images for samples A, B, and C, respectively.

Xiang, Hai-bing; Liu, Jin-song; Cao, Chun-xiang; Xu, Min

2013-01-01

40

Wide-Field Optical Imaging of Interstellar Cirrus Clouds  

Microsoft Academic Search

We have carried out wide-field BVRI CCD imaging of a selection of interstellar ``cirrus'' clouds using the Schmidt telescopes at KPNO and CTIO. In most cases, these images are sensitive enough to detect diffuse optical emission in all of the wavelength bands. The optical images have been compared with IRAS infrared maps to study the properties of the interstellar grains

R. M. Cutri; P. Guhathakurta

1994-01-01

41

Gas cloud infrared image enhancement based on anisotropic diffusion  

NASA Astrophysics Data System (ADS)

Leakage of dangerous gases will not only pollute the environment, but also seriously threat public safety. Thermal infrared imaging has been proved to be an efficient method to qualitatively detect the gas leakage. But some problems are remained, especially when monitoring the leakage in a passive way. For example, the signal is weak and the edge of gas cloud in the infrared image is not obvious enough. However, we notice some important characteristics of the gas plume and therefore propose a gas cloud infrared image enhancement method based on anisotropic diffusion. As the gas plume presents a large gas cloud in the image and the gray value is even inside the cloud, strong forward diffusion will be used to reduce the noise and to expand the range of the gas cloud. Frames subtraction and K-means cluttering pop out the gas cloud area. Forward-and-Backward diffusion is to protect background details. Additionally, the best iteration times and the time step parameters are researched. Results show that the gas cloud can be marked correctly and enhanced by black or false color, and so potentially increase the possibility of gas leakage detection.

Li, Jiakun; Wang, Lingxue; Zhang, Changxing; Long, Yunting; Zhang, Bei

2011-05-01

42

Improved Automated Cloud Classification and Cloud Property Continuity Studies for the Visible Infrared Imager Radiometer Suite (VIIRS)  

Microsoft Academic Search

A new automated cloud classification algorithm for the Visible Infrared Imager Radiometer Suite (VIIRS) is presented. The new algorithm, which is part of the Integrated Data Processing System (IDPS), builds upon the heritage Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) operational cloud top phase algorithms, and includes additional classification categories such as multi-layered clouds and

M. J. Pavolonis; A. K. Heidinger; K. D. Hutchison

2005-01-01

43

Space Shuttle Video Images: An Example of Warm Cloud Lightning  

NASA Technical Reports Server (NTRS)

Warm cloud lightning has been reported in several tropical locations. We have been using the intensified monochrome TV cameras at night during a number of shuttle flights to observe large active thunderstorms and their associated lightning. During a nighttime orbital pass of the STS-70 mission on 17 July 1995 at 07:57:42 GMT, the controllers obtained video imagery of a small cloud that was producing lightning. Data from a GOES infrared image establishes that the cloud top had a temperature of about 271 degrees Kelvin ( -2 degrees Celsius). Since this cloud was electrified to the extent that a lightning discharge did occur, it may be another case of lightning in a cloud that presents little if any evidence of frozen or melting precipitation.

Vaughan, Otha H., Jr.; Boeck, William L.

1998-01-01

44

Gradient Based Image Segmentation for Vein Pattern  

Microsoft Academic Search

The biometrics identification technology based on vein pattern has being developed rapidly in recent years. However, the vein image acquired by near-infrared (NIR) imaging device has low contrast and usually has a mount of noise which make an effective image segmentation be a great challenge. Thresholding is a popular vein image segmentation method, which is easy to calculate and can

Yiding Wang; Hai Wang

2009-01-01

45

MY NASA DATA: Patterns in High Cloud Coverage  

NSDL National Science Digital Library

In this data analysis activity, Students will plot and analyze a time series of data for high cloud coverage from a specified location (home or school) and determine whether or not a seasonal pattern exists. The lesson includes step-by-step instructions for use of the MY NASA DATA Live Access Server (LAS), guiding students through selection of a data set from a location of their choice, importing the data into a spreadsheet, creating graphs, and analyzing data plots. The lesson provides detailed procedures, related links and sample graphs, follow-up questions, extensions, and teacher notes. Designed for student use, MY NASA DATA LAS samples micro datasets from large scientific data archives, and provides structured investigations engaging students in exploration of real data to answer real world questions.

46

Describing the NPOESS Preparatory Project Visible\\/Infrared Imaging Radiometer Suite (VIIRS) Cloud Environmental Data Records  

Microsoft Academic Search

The Visible\\/Infrared Imaging Radiometer Suite (VIIRS) is one of the instruments that make up the suite of sensors on the NPOESS Preparatory Project (NPP) scheduled to launch in 2010. VIIRS will produce seven Environmental Data Records (EDRs) describing cloud properties. The VIIRS Cloud EDRs include the Cloud Optical Thickness (COT), Cloud Effective Particle Size Parameter (CEPS), Cloud Top Pressure (CTP),

C. Hoffman; B. Guenther; H. Kilcoyne; G. Mineart; K. St. Germain; B. Reed

2008-01-01

47

Radiometric cloud imaging with an uncooled microbolometer thermal infrared camera  

Microsoft Academic Search

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\\/(m2

Joseph A. Shaw; Paul W. Nugent; Nathan J. Pust; Brentha Thurairajah; Kohei Mizutani

2005-01-01

48

Moving to the cloud: patterns, integration challenges and opportunities  

Microsoft Academic Search

There has been great interest in cloud computing in recent days with companies like Amazon, Microsoft, Google and others roll out cloud computing infrastructure. Cloud computing offers a number of benefits, organizations and enterprise are hesitant due to concerns on security, control and access to data. The author is of the opinion that customers will be pragmatic and adopt a

Dzaharudin Mansor

2009-01-01

49

Wide angle infrared cloud imaging for measuring cloud statistics in support of earth space optical communication  

NASA Astrophysics Data System (ADS)

Previous research at Montana State University led to the development of the Infrared Cloud Imager (ICI) for measuring downwelling cloud and sky thermal emission for producing cloud coverage statistics using radiometrically calibrated images of the sky. This technique, that was developed primarily for detection of clouds for studies of arctic climate, provides benefits over commonly used systems by producing localized high resolution data in comparison to satellites images, and, in contrast to visible systems, provides continuous day and night operation. As a continuation of the first effort, in collaboration with the Optical Communications Group at the NASA's Jet Propulsion Laboratory (JPL), here we present a new generation of the ICI that can be used to monitor the cloud coverage of a site that can house a ground telescope dedicated to Earth-space optical communication paths. This new instrument, based around the FLIR Photon camera, expands the field of view (FOV) from 20° to 50° (up to 100° in the latest version), reduces instrument size, reduces instrument cost, and extends the time between calibrations to hours instead of minutes. This has been accomplished by characterizing the changes in the output data for changes in the camera's internal temperature while viewing a constant source. Deployment of this instrument has taken place at JPL's Table Mountain facility, CA, and Bozeman, MT.

Nugent, Paul W.; Shaw, Joseph A.; Piazzolla, Sabino

2007-09-01

50

Finding Patterns in Image Databases  

Microsoft Academic Search

\\u000a Image is one of the most widely used media in the world. Many real-life applications have been designed to process and analyze\\u000a large number of images. For example, in the terrain matching applications, we have thousands of images that are returned by\\u000a the satellite which need to be processed and mapped; in the archaeology domain, all ancient artifacts are photographed

Wynne Hsu; Mong Li Lee; Jing Dai

51

Enhanced IR imagery of cloud top temperatures, heights, cloud types and organizational patterns  

NSDL National Science Digital Library

Dorothea Ivanova, Embry-Riddle Aeronautical University Summary The object of this activity is to find enhanced IR imagery, to interpret cloud top temperatures and heights and to identify cloud types and ...

Ivanova, Dorothea

52

Describing the NPOESS Preparatory Project Visible/Infrared Imaging Radiometer Suite (VIIRS) Cloud Environmental Data Records  

NASA Astrophysics Data System (ADS)

The Visible/Infrared Imaging Radiometer Suite (VIIRS) is one of the instruments that make up the suite of sensors on the NPOESS Preparatory Project (NPP) scheduled to launch in 2010. VIIRS will produce seven Environmental Data Records (EDRs) describing cloud properties. The VIIRS Cloud EDRs include the Cloud Optical Thickness (COT), Cloud Effective Particle Size Parameter (CEPS), Cloud Top Pressure (CTP), Cloud Top Height (CTH), Cloud Top Temperature (CTT), Cloud Cover/Layers (CCL), and Cloud Base Height (CBH). This paper will describe the VIIRS algorithms used to generate these EDRs and provide a current estimate of performance based on pre-Launch test data.

Hoffman, C.; Guenther, B.; Kilcoyne, H.; Mineart, G.; St. Germain, K.; Reed, B.

2008-12-01

53

Image Distribution Mechanisms in Large Scale Cloud Providers  

Microsoft Academic Search

This paper presents the various mechanisms for virtual machine image distribution within a large batch farm and between sites that offer cloud computing services. The work is presented within the context of the Large Hadron Collider Computing Grid (LCG), it has two main goals. First it aims at presenting the CERN specific mechanisms that have been put in place to

Romain Wartel; Tony Cass; Belmiro Moreira; Ewan Roche; Manuel Guijarro; Sebastien Goasguen; Ulrich Schwickerath

2010-01-01

54

Geometric Cloud Top Height Assignment by Geosynchronous Meteorological Satellite Images  

Microsoft Academic Search

In this research, the biases for Geometric Cloud Top Height (CTH) assignment are simulated for the current operational geostationary satellite constellation. The simulation shows that the geometric CTHs are best retrieved when the two satellites are separated by 60 degrees and presents CTHs properties for various satellite configurations. In addition, a case study based on GOES-10\\/12 images is shown to

Feng Lu; Jianmin Xu; W. Paul Menzel; Christopher S. Velden

2009-01-01

55

Extraction of cloud statistics from whole sky imaging cameras  

SciTech Connect

Computer codes have been developed to extract basic cloud statistics from whole sky imaging (WSI) cameras. This report documents, on an algorithmic level, the steps and processes underlying these codes. Appendices comment on code details and on how to adapt to future changes in either the source camera or the host computer.

Kegelmeyer, W.P. Jr.

1994-03-01

56

An Integrated Method to Generate a Cloud-Free Image Automatically Based on Landsat5 Data  

Microsoft Academic Search

How to remove cloud and shadow completely through several (more than 2) images is considered in this paper. Based on landsat5 data, when enter several images, it can automatically find one image with the least cloud and shadow as the base image. Then mosaic with other images which are taken in different time for the same area, an image without

Ying-zhao Ma; Wei-li Jiao; Gui-zhou Wang; Teng-fei Long; Wei Wang

2010-01-01

57

Cloud Detection with the Earth Polychromatic Imaging Camera (EPIC)  

NASA Technical Reports Server (NTRS)

The Earth Polychromatic Imaging Camera (EPIC) on board the Deep Space Climate Observatory (DSCOVR) would provide a unique opportunity for Earth and atmospheric research due not only to its Lagrange point sun-synchronous orbit, but also to the potential for synergistic use of spectral channels in both the UV and visible spectrum. As a prerequisite for most applications, the ability to detect the presence of clouds in a given field of view, known as cloud masking, is of utmost importance. It serves to determine both the potential for cloud contamination in clear-sky applications (e.g., land surface products and aerosol retrievals) and clear-sky contamination in cloud applications (e.g., cloud height and property retrievals). To this end, a preliminary cloud mask algorithm has been developed for EPIC that applies thresholds to reflected UV and visible radiances, as well as to reflected radiance ratios. This algorithm has been tested with simulated EPIC radiances over both land and ocean scenes, with satisfactory results. These test results, as well as algorithm sensitivity to potential instrument uncertainties, will be presented.

Meyer, Kerry; Marshak, Alexander; Lyapustin, Alexei; Torres, Omar; Wang, Yugie

2011-01-01

58

Relating large scale dynamic patterns and cloud properties at Darwin, Australia  

NASA Astrophysics Data System (ADS)

Improving cloud parameterizations in large scale models hinges on understanding the statistical connection between large scale dynamics and the cloud fields they produce. We use an atmospheric classification technique developed and applied by Marchand and coauthors (2009, J. Climate) to investigate the relationship between synoptic scale dynamic patterns and cloud properties. Our technique uses a neural net classifier acting on reanalysis data to identify atmospheric states and then uses independent cloud radar observations of vertical cloud occurrence to test the statistical significance of each state. Here we apply our method to four years of ECMWF reanalysis data and associated vertically pointing millimeter wavelength cloud radar observations from the Atmospheric Systems Research program site in Darwin, Australia. From this data we produce a set of atmospheric states for the region, each with its own distinct meteorology. Given simultaneous time series of our state classification and other observables, we can determine the distribution of observables associated with each dynamical state. Observables include ground-based quantities such as cloud occurrence, precipitation, liquid water path, cloud optical depth and surface fluxes, and satellite quantities such as fractional cloud cover, top-of-atmosphere fluxes and cloud effect, and retrieved cloud properties. The multi-year record allows us to investigate the seasonal variability of the dynamic patterns and the influence of the MJO. In addition, we can examine the diurnal cycle of the states, the duration of particular patterns (since we classify the atmospheric pattern every 3 hours) and the transition probability from any state to any other state. Our analysis approach is, to the best or our knowledge, unique in the way it statistically links large-scale dynamics to cloud occurrence and, subsequently, other physical observables. It provides new opportunities for analysis of the behavior of the atmosphere. Our near term goal is to apply this technique to climate model output to determine to what extent climate models can duplicate the observed linkage between dynamical states and associated hydrological and radiative properties.

Evans, S. M.; Marchand, R.; Ackerman, T. P.

2010-12-01

59

Clouds removal from remotely sensed images by using a bandelet-based reconstruction technique  

Microsoft Academic Search

The recurrent presence of clouds and clouds shadows in aerial or remotely sensed images is an awkward problem that severely limits the regular exploitations capability of these images. Removing cloud-contaminated portions of the image and then filling in the missing data represent an important photo editing cumbersome task. The intent of this work is to propose a technique for the

Aldo Maalouf; Philippe Carré; Bertrand Augereau; Christine Fernandez-Maloigne

2007-01-01

60

Multiscale image enhancement of chromosome banding patterns  

Microsoft Academic Search

Visual examination of chromosome banding patterns is an important means of chromosome analysis. Cytogeneticists compare their patient's chromosome image against the prototype normal\\/abnormal human chromosome banding patterns. Automated chromosome analysis instruments facilitate this by digitally enhancing the chromosome images. Currently available systems employing traditional highpass\\/bandpass filtering and\\/or histogram equalization are approximately equivalent to photomicroscopy in their ability to support the

Qiang Wu; Kenneth R. Castleman

1996-01-01

61

The algorithm to generate color point-cloud with the registration between panoramic image and laser point-cloud  

NASA Astrophysics Data System (ADS)

Laser point cloud contains only intensity information and it is necessary for visual interpretation to obtain color information from other sensor. Cameras can provide texture, color, and other information of the corresponding object. Points with color information of corresponding pixels in digital images can be used to generate color point-cloud and is conducive to the visualization, classification and modeling of point-cloud. Different types of digital cameras are used in different Mobile Measurement Systems (MMS).the principles and processes for generating color point-cloud in different systems are not the same. The most prominent feature of the panoramic images is the field of 360 degrees view angle in the horizontal direction, to obtain the image information around the camera as much as possible. In this paper, we introduce a method to generate color point-cloud with panoramic image and laser point-cloud, and deduce the equation of the correspondence between points in panoramic images and laser point-clouds. The fusion of panoramic image and laser point-cloud is according to the collinear principle of three points (the center of the omnidirectional multi-camera system, the image point on the sphere, the object point). The experimental results show that the proposed algorithm and formulae in this paper are correct.

Zeng, Fanyang; Zhong, Ruofei

2014-03-01

62

Fringe pattern denoising via image decomposition.  

PubMed

Filtering off noise from a fringe pattern is one of the key tasks in optical interferometry. In this Letter, using some suitable function spaces to model different components of a fringe pattern, we propose a new fringe pattern denoising method based on image decomposition. In our method, a fringe image is divided into three parts: low-frequency fringe, high-frequency fringe, and noise, which are processed in different spaces. An adaptive threshold in wavelet shrinkage involved in this algorithm improves its denoising performance. Simulation and experimental results show that our algorithm obtains smooth and clean fringes with different frequencies while preserving fringe features effectively. PMID:22297373

Fu, Shujun; Zhang, Caiming

2012-02-01

63

New cloud free line of sight statistics measured with digital whole sky imagers  

Microsoft Academic Search

Cloud Free Line of Sight (CFLOS) statistics can be important to a number of applications involving transmittance of light through the atmosphere, including laser propagation, light propagation, and detection of objects by humans and instruments. This paper will discuss Cloud Free Line of Sight (CFLOS) and cloud persistence statistics determined from cloud measurements taken with Whole Sky Imagers (WSI). The

Janet E. Shields; Art R. Burden; Richard W. Johnson; Monette E. Karr; Justin G. Baker

2005-01-01

64

X-ray imaging of nanostructure patterns  

SciTech Connect

A Fresnel zone plate lens, with a nominal outer zone width of 400 A, has been used to image nanostructures with soft x-ray synchrotron radiation at 45 A wavelength with the Goettingen x-ray microscope at BESSY in Berlin. The structures, consisting of gold lines in thin silicon nitride membranes, were selected for tests of spatial resolution and image forming capabilities. Several patterns associated with deep submicron electronic circuits were also imaged, showing clearly resolved features smaller than 0.1 ..mu..m. Images of periodic structures, including 600 A lines on 2000 A centers, suggest a spatial resolution approaching the theoretical limit of approximately 500 A.

Vladimirsky, Y.; Kern, D.; Meyer-Ilse, W.; Attwood, D.

1989-01-16

65

A precise APT receiver for cloud and sea surface temperature imaging  

NASA Astrophysics Data System (ADS)

Use of APT (automatic picture transmission) reduced-resolution thermal and NIR AVHRR data from the NOAA weather satellites has been demonstrated for a variety of purposes, including the real-time mapping of weather patterns and sea-surface temperatures. Lower-cost systems have been used for producing cloud images, but have not preserved the data quality needed for water-temperature mapping. Higher-quality commercial receiving systems in the past have cost over $50,000. This paper presents preliminary examples of imagery collected from a simplified receiver, digitizer, and display system which uses custom electronics to input image data to a PC-based display system. The temperature sensitivity is designed to be sufficient to map coastal sea-surface-temperature patterns (on the order of 0.5 C), although this has not yet been achieved with the system. The PC-based display software supports a wide variety of image corrections and enhancements.

Gower, J. F. R.; Lowe, T. B.; Wannamaker, B.

66

Attenuation correction in SPECT images reconstructed on multi-resolution point clouds  

Microsoft Academic Search

Irregular point cloud distributions of grid points are used to form a tetrahedral mesh for representation of images reconstructed from projections. Previously we demonstrated that point clouds provide a significant gain in sparseness of a 3D image representation without apparent loss in resolution. Point clouds have been suggested as natural representations for factor analysis of dynamic SPECT data. In order

Rostyslav Boutchko; Arkadiusz Sitek; Grant T. Gullberg

2007-01-01

67

CLOUDS.  

National Technical Information Service (NTIS)

This report is an in-depth Users Manual for the ANSI FORTRAN computer program CLOUDS. CLOUDS is designed in two major blocks: cloud field generation and cloud-free line-of-sight (CFLOS) calculation. The cloud field generation block models observed cloud f...

M. K. Seager

1979-01-01

68

Modified control software for imaging ultracold atomic clouds  

NASA Astrophysics Data System (ADS)

A charge-coupled device (CCD) camera capable of taking high-quality images of ultracold atomic samples can often represent a significant portion of the equipment costs in atom trapping experiment. We have modified the commercial control software of a CCD camera designed for astronomical imaging to take absorption images of ultracold rubidium clouds. This camera is sensitive at 780 nm and has been modified to take three successive 16-bit images at full resolution. The control software can be integrated into a Matlab graphical user interface with fitting routines written as Matlab functions. This camera is capable of recording high-quality images at a fraction of the cost of similar cameras typically used in atom trapping experiments.

Whitaker, D. L.; Sharma, A.; Brown, J. M.

2006-12-01

69

Multiscale image enhancement of chromosome banding patterns  

NASA Astrophysics Data System (ADS)

Visual examination of chromosome banding patterns is an important means of chromosome analysis. Cytogeneticists compare their patient's chromosome image against the prototype normal/abnormal human chromosome banding patterns. Automated chromosome analysis instruments facilitate this by digitally enhancing the chromosome images. Currently available systems employing traditional highpass/bandpass filtering and/or histogram equalization are approximately equivalent to photomicroscopy in their ability to support the detection of band pattern alterations. Improvements in chromosome image display quality, particularly in the detail of the banding pattern, would significantly increase the cost-effectiveness of these systems. In this paper we present our work on the use of multiscale transform and derivative filtering for image enhancement of chromosome banding patterns. A steerable pyramid representation of the chromosome image is generated by a multiscale transform. The derivative filters are designed to detect the bands of a chromosome, and the steerable pyramid transform is chosen based on its desirable properties of shift and rotation invariance. By processing the transform coefficients that correspond to the bands of the chromosome in the pyramid representation, contrast enhancement of the chromosome bands can be achieved with designed flexibility in scale, orientation and location. Compared with existing chromosome image enhancement techniques, this new approach offers the advantage of selective chromosome banding pattern enhancement that allows designated detail analysis. Experimental results indicate improved enhancement capabilities and promise more effective visual aid to comparison of chromosomes to the prototypes and to each other. This will increase the ability of automated chromosome analysis instruments to assist the evaluation of chromosome abnormalities in clinical samples.

Wu, Qiang; Castleman, Kenneth R.

1996-10-01

70

Cultural Relic 3D Reconstruction from Digital Images and Laser Point Clouds  

Microsoft Academic Search

This paper proposes a method to combine the digital images and Laser point clouds to reconstruct the 3D model of the archaic glockenspiel. All the stations of the Laser point clouds are connected according to the ICP arithmetic. Then image matching is used to register the high resolution digital images and the Laser synchronous images to gain the corresponding texture

Jie Liu; Jianqing Zhang; Jia Xu

2008-01-01

71

Estimating cloud top height and spatial displacement from scan-synchronous GOES images using simplified IR-based stereoscopic analysis  

Microsoft Academic Search

An efficient method for estimating cloud top heights and correcting cloud image spatial displacements was developed. The method applies stereoscopic analysis to a pair of scan-synchronous infrared cloud images received from two GOES satellites using a piecewise linear approximation of the relationship between height and infrared brightness temperature of top of the cloud element. The algorithm solves for cloud top

Shayesteh E. Mahani; Xiaogang Gao; Soroosh Sorooshian; Bisher Imam

2000-01-01

72

High Quality Typhoon Cloud Image Restoration by Combining Genetic Algorithm with Contourlet Transform  

SciTech Connect

An efficient typhoon cloud image restoration algorithm is proposed. Having implemented contourlet transform to a typhoon cloud image, noise is reduced in the high sub-bands. Weight median value filter is used to reduce the noise in the contourlet domain. Inverse contourlet transform is done to obtain the de-noising image. In order to enhance the global contrast of the typhoon cloud image, in-complete Beta transform (IBT) is used to determine non-linear gray transform curve so as to enhance global contrast for the de-noising typhoon cloud image. Genetic algorithm is used to obtain the optimal gray transform curve. Information entropy is used as the fitness function of the genetic algorithm. Experimental results show that the new algorithm is able to well enhance the global for the typhoon cloud image while well reducing the noises in the typhoon cloud image.

Zhang Changjiang; Wang Xiaodong [College of Mathematics, Physics and Information Engineering, Zhejiang Normal University, Jinhua (China)

2008-11-06

73

Ground-based full-sky imaging polarimetry of rapidly changing skies and its use for polarimetric cloud detection.  

PubMed

For elimination of the shortcomings of imaging polarimeters that take the necessary three pictures sequentially through linear-polarization filters, a three-lens, three-camera, full-sky imaging polarimeter was designed that takes the required pictures simultaneously. With this polarimeter, celestial polarization patterns can be measured even if rapid temporal changes occur in the sky: under cloudy sky conditions, or immediately after sunrise or prior to sunset. One of the possible applications of our polarimeter is the ground-based detection of clouds. With use of the additional information of the degree and the angle of polarization patterns of cloudy skies measured in the red (650 nm), green (550 nm), and blue (450 nm) spectral ranges, improved algorithms of radiometric cloud detection can be offered. We present a combined radiometric and polarimetric algorithm that performs the detection of clouds more efficiently and reliably as compared with an exclusively radiometric cloud-detection algorithm. The advantages and the limits of three-lens, three-camera, full-sky imaging polarimeters as well as the possibilities of improving our polarimetric cloud detection method are discussed briefly. PMID:11905581

Horváth, Gábor; Barta, Andras; Gál, József; Suhai, Bence; Haiman, Ottó

2002-01-20

74

Imaging sensor constellation for tomographic chemical cloud mapping.  

PubMed

A sensor constellation capable of determining the location and detailed concentration distribution of chemical warfare agent simulant clouds has been developed and demonstrated on government test ranges. The constellation is based on the use of standoff passive multispectral infrared imaging sensors to make column density measurements through the chemical cloud from two or more locations around its periphery. A computed tomography inversion method is employed to produce a 3D concentration profile of the cloud from the 2D line density measurements. We discuss the theoretical basis of the approach and present results of recent field experiments where controlled releases of chemical warfare agent simulants were simultaneously viewed by three chemical imaging sensors. Systematic investigations of the algorithm using synthetic data indicate that for complex functions, 3D reconstruction errors are less than 20% even in the case of a limited three-sensor measurement network. Field data results demonstrate the capability of the constellation to determine 3D concentration profiles that account for ~?86%? of the total known mass of material released. PMID:19340137

Cosofret, Bogdan R; Konno, Daisei; Faghfouri, Aram; Kindle, Harry S; Gittins, Christopher M; Finson, Michael L; Janov, Tracy E; Levreault, Mark J; Miyashiro, Rex K; Marinelli, William J

2009-04-01

75

Analysis of interstellar cloud structure based on IRAS images  

NASA Technical Reports Server (NTRS)

The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct densely sampled column density maps of star-forming clouds, column density images of four nearby cloud complexes were constructed from IRAS data. The regions have various degrees of star formation activity, and most of them have probably not been affected much by the disruptive effects of young massive stars. The largest region, the Scorpius-Ophiuchus cloud complex, covers about 1000 square degrees (it was subdivided into a few smaller regions for analysis). Much of the work during the early part of the project focused on an 80 square degree region in the core of the Taurus complex, a well-studied region of low-mass star formation.

Scalo, John M.

1992-01-01

76

How the clear-sky angle of polarization pattern continues underneath clouds: full-sky measurements and implications for animal orientation.  

PubMed

One of the biologically most important parameters of the cloudy sky is the proportion P of the celestial polarization pattern available for use in animal navigation. We evaluated this parameter by measuring the polarization patterns of clear and cloudy skies using 180 degrees (full-sky) imaging polarimetry in the red (650 nm), green (550 nm) and blue (450 nm) ranges of the spectrum under clear and partly cloudy conditions. The resulting data were compared with the corresponding celestial polarization patterns calculated using the single-scattering Rayleigh model. We show convincingly that the pattern of the angle of polarization (e-vectors) in a clear sky continues underneath clouds if regions of the clouds and parts of the airspace between the clouds and the earth surface (being shady at the position of the observer) are directly lit by the sun. The scattering and polarization of direct sunlight on the cloud particles and in the air columns underneath the clouds result in the same e-vector pattern as that present in clear sky. This phenomenon can be exploited for animal navigation if the degree of polarization is higher than the perceptual threshold of the visual system, because the angle rather than the degree of polarization is the most important optical cue used in the polarization compass. Hence, the clouds reduce the extent of sky polarization pattern that is useful for animal orientation much less than has hitherto been assumed. We further demonstrate quantitatively that the shorter the wavelength, the greater the proportion of celestial polarization that can be used by animals under cloudy-sky conditions. As has already been suggested by others, this phenomenon may solve the ultraviolet paradox of polarization vision in insects such as hymenopterans and dipterans. The present study extends previous findings by using the technique of 180 degrees imaging polarimetry to measure and analyse celestial polarization patterns. PMID:11551983

Pomozi, I; Horváth, G; Wehner, R

2001-09-01

77

Clouds  

NSDL National Science Digital Library

Clouds comprise a wonderful focus for classroom study. They're ubiquitous, ever-changing, scientifically interesting and, most importantly for teachers, they're cheap. The material presented here includes sections on cloud formation, cloud types, cloud pictures, other cloud-related phenomena, and a glossary.

Wozniak, Carl

78

Research on texture feature of RS image based on cloud model  

NASA Astrophysics Data System (ADS)

This paper presents a new method applied to texture feature representation in RS image based on cloud model. Aiming at the fuzziness and randomness of RS image, we introduce the cloud theory into RS image processing in a creative way. The digital characteristics of clouds well integrate the fuzziness and randomness of linguistic terms in a unified way and map the quantitative and qualitative concepts. We adopt texture multi-dimensions cloud to accomplish vagueness and randomness handling of texture feature in RS image. The method has two steps: 1) Correlativity analyzing of texture statistical parameters in Grey Level Co-occurrence Matrix (GLCM) and parameters fuzzification. GLCM can be used to representing the texture feature in many aspects perfectly. According to the expressive force of texture statistical parameters and by Correlativity analyzing of texture statistical parameters, we can abstract a few texture statistical parameters that can best represent the texture feature. By the fuzziness algorithm, the texture statistical parameters can be mapped to fuzzy cloud space. 2) Texture multi-dimensions cloud model constructing. Based on the abstracted texture statistical parameters and fuzziness cloud space, texture multi-dimensions cloud model can be constructed in micro-windows of image. According to the membership of texture statistical parameters, we can achieve the samples of cloud-drop. By backward cloud generator, the digital characteristics of texture multi-dimensions cloud model can be achieved and the Mathematical Expected Hyper Surface(MEHS) of multi-dimensions cloud of micro-windows can be constructed. At last, the weighted sum of the 3 digital characteristics of micro-window cloud model was proposed and used in texture representing in RS image. The method we develop is demonstrated by applying it to texture representing in many RS images, various performance studies testify that the method is both efficient and effective. It enriches the cloud theory, and proposes a new idea for image texture representing and analyzing, especially RS image.

Wang, Zuocheng; Xue, Lixia

2008-10-01

79

Characterizing Spatial Patterns of Cloud Cover And Fog Inundation in the California Channel Islands  

NASA Astrophysics Data System (ADS)

Coastal forests in Mediterranean climates are frequently covered by clouds or immersed in fog. Previous studies suggest that clouds strongly modulate forest distributions as well as carbon and water budgets in these semi-arid environments. Both low level stratocumulus cloud cover and fog can enhance the water status of vegetation along the Californian coast and the Channel Islands by reducing insolation and raising relative humidity and thus reducing evapotranspiration, while also potentially supplying water directly to the landscape from fog-drip during otherwise warm and rainless summers. While cloud cover and fog can ameliorate summer drought stress and enhance soil water budgets, they often have different spatial and temporal patterns. The resulting shifts in relative ecological importance of fog and stratus are largely unknown. The overall objective of this project was to map spatial and temporal distributions of daytime cloud cover frequency for the California Channel Islands, and to predict probabilities of surface cloud (fog) contact and immersion for these islands. Daytime cloud cover maps were generated for the northern Channel Islands using GOES satellite imagery for the years 1996-2012. To discriminate fog from stratus the base of the cloud height was constrained by using airport cloud ceiling data and topographic information. In order to observe variation in fog frequency at scales relevant to species distributions on the Channel Islands the native GOES resolution was downscaled by using radiosonde and reanalysis data. Satellite derived estimates of cloud cover and fog were correlated with field measurements of insolation, fog drip and leaf wetness on Santa Rosa and Santa Cruz islands. This enabled spatial and temporal extrapolation to understand seasonal and inter-annual variations in cloud cover frequency and fog inundation and drip and will be important for future water balance modeling, studies of coastal vegetation distributions and for better identification of locations where native vegetation restoration efforts are likely to be most successful.

Rastogi, B.; Fischer, D. T.; Williams, P.; Iacobellis, S.; McEachern, K.; Still, C. J.

2013-12-01

80

Global patterns of solar influence on high cloud cover and role of sea surface temperature  

NASA Astrophysics Data System (ADS)

Climate change and global warming have become usual terms nowadays but mechanisms that could explain their causes are not understood. One of the main sources of uncertainty in climate projections is represented by clouds, which, due to various feedback, have an important influence on Earth's radiation budget. The cloud representation in General Circulation Models relies largely on constraints derived from observations. Solar impact on climate is largely unknown and some coupling mechanisms between solar and climate variability rely on the Sea Surface Temperature. We identified solar forced patterns in observed high cloud cover (HCC) based on associations with known fingerprints of the same forcing on cloud cover obtained from reanalysis data, on observed surface air temperature (SAT), sea level pressure (SLP) and sea surface temperature (SST) fields. The solar influence on HCC has maximum amplitudes over the Pacific basin, where high cloud cover anomalies are distributed in bands of alternating polarities, indicating a SST influence on high clouds through convection. The HCC structure induced by the solar cycle appears to be generated through both so-called "top-down" and "bottom-up" mechanisms of solar influence on climate. Clouds are dependent on the relative humidity which is strongly influenced by the dynamics and SST, thus we also review possible mechanisms connecting SST with clouds, solar radiation, cosmic rays, precipitations and aerosols.

Voiculescu, Mirela; Dima, Mihai; Constantin, Daniel

2014-05-01

81

Cloud Thickness and Satellite Images (title provided or enhanced by cataloger)  

NSDL National Science Digital Library

This applet explores how the thickness of a cloud changes the way it looks from a satellite. The image is in the visible part of the spectrum, and the radiant energy is a function of not just temperature, as in the case of infrared images. The cloud thickness, its effective brightness, and the surface temperature can be modified while observing the satellite image.

Whittaker, Tom; Ackerman, Steve

82

Global Moderate Resolution Imaging Spectroradiometer (MODIS) cloud detection and height evaluation using CALIOP  

Microsoft Academic Search

A global 2-month comparison is presented between the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and the Moderate Resolution Imaging Spectroradiometer (MODIS) for both cloud detection and cloud top height (CTH) retrievals. Both CALIOP and MODIS are part of the NASA A-Train constellation of satellites and provide continuous near-coincident measurements that result in over 28 million cloud detection comparisons and over

R. E. Holz; S. A. Ackerman; F. W. Nagle; R. Frey; S. Dutcher; R. E. Kuehn; M. A. Vaughan; B. Baum

2008-01-01

83

Advancements in identifying cirrus and multilayered cloud systems from operational satellite imagers at night  

Microsoft Academic Search

Radiances and brightness temperatures from three near-infrared\\/infrared channels that are available on most current and past satellite imagers were used to develop automated algorithms for identifying multilayered cloud systems (cloud overlap) and cirrus clouds at night. The cloud overlap algorithm uses information from the 3.75 micron, 11 micron, and 12 micron regions of the spectrum and the cirrus algorithm uses

Michael J. Pavolonis; Andrew K. Heidinger

2005-01-01

84

Radar imaging of ocean surface patterns  

NASA Technical Reports Server (NTRS)

The paper presents some examples of imaging radar oceanographic observations and discusses physical phenomena on the surface that may cause the radar image. The different ocean scattering theories are briefly discussed, including the tangent plane model, the Bragg-Rice model, and the Rayleigh scattering model. All but one of the images presented were obtained with an L-band HH-polarized radar; they include deep-ocean swells, coastal swells, wave refractions, internal waves, ship wakes, abrupt transitions in open-ocean surface roughness, surface slicks, island wind shadowing, and currents. Analyses are shown to suggest that the primary source of the L-band imagery of ocean surface patterns is the variation of small-scale surface roughness and local tilt angle. It is also noted that surface irregularities behave as isotropic scatterers for a radar wavelength of 25 cm.

Brown, W. E., Jr.; Elachi, C.; Thompson, T. W.

1976-01-01

85

Jovian Ammonia Cloud Identification and Color Analyses from Hyperspectral Imaging  

NASA Astrophysics Data System (ADS)

Narrowband visible and near-infrared images of Jupiter were acquired at the Apache Point Observatory 3.5-meter telescope from 26-27 June and 04 July 2007 with the New Mexico State University Acousto-optic Imaging Camera (NAIC) to study atmospheric spectral characteristics. Over 3000 images were collected and map-projected, yielding spectral image cubes that span 480-900 nm with 2 nm resolution (1 nm resolution after deconvolution) and spatially cover 85% of jovian longitudes. We report the detection of spectrally identifiable ammonia clouds (SIACs) through the ammonia absorption features centered at 647 nm and 790 nm, which may be the first identification of SIACs using narrowband visible imaging. The observed SIACs predominately reside in the range of 1° to 4° N latitude (planetographic) and are also found in the turbulent wake region northwest of the Great Red Spot (GRS), which is in agreement with the analysis of Galileo NIMS observations by Baines et al. (2002, Icarus 159, 74-94). SIAC size and spatial distributions and temporal evolution are discussed. Additionally, color analyses were conducted for a jovian chromophore investigation using principle component analysis and nonnegative matrix factorization. Results are compared to a color analysis of HST observations from May-July 2008 of the passage of the GRS and Oval BA (Simon-Miller, this meeting). This work is funded by NSF award AST0628919.

Strycker, Paul D.; Chanover, N.; Voelz, D.; Simon-Miller, A.

2008-09-01

86

Congruence analysis of point clouds from unstable stereo image sequences  

NASA Astrophysics Data System (ADS)

This paper deals with the correction of exterior orientation parameters of stereo image sequences over deformed free-form surfaces without control points. Such imaging situation can occur, for example, during photogrammetric car crash test recordings where onboard high-speed stereo cameras are used to measure 3D surfaces. As a result of such measurements 3D point clouds of deformed surfaces are generated for a complete stereo sequence. The first objective of this research focusses on the development and investigation of methods for the detection of corresponding spatial and temporal tie points within the stereo image sequences (by stereo image matching and 3D point tracking) that are robust enough for a reliable handling of occlusions and other disturbances that may occur. The second objective of this research is the analysis of object deformations in order to detect stable areas (congruence analysis). For this purpose a RANSAC-based method for congruence analysis has been developed. This process is based on the sequential transformation of randomly selected point groups from one epoch to another by using a 3D similarity transformation. The paper gives a detailed description of the congruence analysis. The approach has been tested successfully on synthetic and real image data.

Jepping, C.; Bethmann, F.; Luhmann, T.

2014-06-01

87

Microwave Imager Measures Sea Surface Temperature Through Clouds  

NASA Technical Reports Server (NTRS)

This image was acquired over Tropical Atlantic and U.S. East Coast regions on Aug. 22 - Sept. 23, 1998. Cloud data were collected by the Geostationary Operational Environmental Satellite (GOES). Sea Surface Temperature (SST) data were collected aboard the NASA/NASDA Tropical Rainfall Measuring Mission (TRMM) satellite by The TRMM Microwave Imager (TMI). TMI is the first satellite microwave sensor capable of accurately measuring sea surface temperature through clouds, as shown in this scene. For years scientists have known there is a strong correlation between sea surface temperature and the intensity of hurricanes. But one of the major stumbling blocks for forecasters has been the precise measurement of those temperatures when a storm begins to form. In this scene, clouds have been made translucent to allow an unobstructed view of the surface. Notice Hurricane Bonnie approaching the Carolina Coast (upper left) and Hurricane Danielle following roughly in its path (lower right). The ocean surface has been falsely colored to show a map of water temperature--dark blues are around 75oF, light blues are about 80oF, greens are about 85oF, and yellows are roughly 90oF. A hurricane gathers energy from warm waters found at tropical latitudes. In this image we see Hurricane Bonnie cross the Atlantic, leaving a cooler trail of water in its wake. As Hurricane Danielle followed in Bonnie's path, the wind speed of the second storm dropped markedly, as available energy to fuel the storm dropped off. But when Danielle left Bonnie's wake, wind speeds increased due to temperature increases in surface water around the storm. As a hurricane churns up the ocean, it's central vortex draws surface heat and water into the storm. That suction at the surface causes an upwelling of deep water. At depth, tropical ocean waters are significantly colder than water found near the surface. As they're pulled up to meet the storm, those colder waters essentially leave a footprint in the storm's wake which might last as long as two weeks. Forecasters can quantify the difference in surface temperatures between this footprint and the surrounding temperatures and use that information to better predict storm intensity. If another storm intersects with this cold water trail, it is likely to lose significant strength due to the fact that the colder water does not contain as much potential energy as warm water. TRMM Fact Sheet Predicting Hurricane Intensity Far from Land Remote Sensing Systems Image courtesy TRMM Project, Remote Sensing Systems, and Scientific Visualization Studio, NASA Goddard Space Flight Center

2002-01-01

88

Aerosol patterns and aerosol-cloud-interactions off the West African Coast based on the A-train formation  

NASA Astrophysics Data System (ADS)

In this study, spatial and temporal aerosol patterns off the Western African coast are characterized and related to cloud properties, based on satellite data Atmospheric aerosols play a key role in atmospheric processes and influence our environmental system in a complex way. Their identification, characterization, transport patterns as well as their interactions with clouds pose major challenges. Especially the last aspect reveals major uncertainties in terms of the Earth's radiation budget as reported in the IPCC's Fourth Assessment Report (IPCC, 2007). Western and Southern Africa are dominated by two well-known source types of atmospheric aerosols. First, the Saharan Desert is the world's largest aeolian dust emitting source region. Second, biomass burning aerosol is commonly transported off-shore further south (Kaufman et al., 2005). Both aerosol types influence Earth's climate in different manners and can be detected by the MODIS (MODerate resolution Imaging Spectrometer) sensor onboard the EOS platforms as they propagate to the Central and Southern Atlantic. The motivation of this study was to reveal the seasonal pattern of the Saharan dust transport based on an observation period of 11 years and trying to explain the meteorological mechanisms. North African dust plumes are transported along a latitude of 19°N in July and 6°N in January. The seasonally fluctuating intensities adapt to the annual cycle of wind and precipitation regimes. A strong relationship is found between the spatial shift of the Azores High and the Saharan dust load over the middle Atlantic Ocean. Monthly Aerosol Optical Thickness products of Terra MODIS and NCEP-DOE (National Centers for Environmental Predictions) Reanalysis II data are used for this purpose. The relationship between aerosol and cloud droplet parameters is blurred by high sensitivities to aerosol size and composition (Feingold, 2003; McFiggans et al., 2006) as well as meteorological context (Ackerman et al., 2004). Satellite data from the A-train formation, including the Aqua, CloudSat and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) are used to analyze aerosol-cloud-interactions in detail, along with re-analysis data to constrain by meteorological conditions. Information about the vertical and geographical distribution of different aerosol types and cloud parameters will lead to a process-oriented understanding of these issues on a regional scale. Ackerman, A., Kirkpatrick, M., Stevens, D., & Toon, O. (2004). The impact of humidity above stratiform clouds on indirect aerosol climate forcing. Nature, 432(December), 1014-1017. doi:10.1038/nature03137.1. Feingold, G. (2003). First measurements of the Twomey indirect effect using ground-based remote sensors. Geophysical Research Letters, 30(6), 1287. doi:10.1029/2002GL016633 IPCC. (2007). Climate Change 2007: The Physical Science Basis. Contribution of Working group I to the Fourth Assessment Report of the Interfovernmental Panel on climate Change. Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Kaufman, Y. J., Koren, I., Remer, L. A., Tanré, D., Ginoux, P., & Fan, S. (2005). Dust transport and deposition observed from the Terra-Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean. Journal of Geophysical Research, 110(D10), 1-16. doi:10.1029/2003JD004436 McFiggans, G., Artaxo, P., Baltensperger, U., Coe, H., Facchini, M. C., Feingold, G., Fuzzi, S., et al. (2006). The effect of physical and chemical aerosol properties on warm cloud droplet activation. Atmospheric Chemistry and Physics, 6(9), 2593-2649. doi:10.5194/acp-6-2593-2006

Fuchs, Julia; Bendix, Jörg; Cermak, Jan

2013-04-01

89

Astronomy In The Cloud: Using Mapreduce For Image Coaddition  

NASA Astrophysics Data System (ADS)

In the coming decade, astronomical surveys of the sky will generate tens of terabytes of images and detect hundreds of millions of sources every night. The study of these sources will involve computational challenges such as anomaly detection, classification, and moving object tracking. Since such studies require the highest quality data, methods such as image coaddition, i.e., registration, stacking, and mosaicing, will be critical to scientific investigation. With a requirement that these images be analyzed on a nightly basis to identify moving sources, e.g., asteroids, or transient objects, e.g., supernovae, these datastreams present many computational challenges. Given the quantity of data involved, the computational load of these problems can only be addressed by distributing the workload over a large number of nodes. However, the high data throughput demanded by these applications may present scalability challenges for certain storage architectures. One scalable data-processing method that has emerged in recent years is MapReduce, and in this paper we focus on its popular open-source implementation called Hadoop. In the Hadoop framework, the data is partitioned among storage attached directly to worker nodes, and the processing workload is scheduled in parallel on the nodes that contain the required input data. A further motivation for using Hadoop is that it allows us to exploit cloud computing resources, i.e., platforms where Hadoop is offered as a service. We report on our experience implementing a scalable image-processing pipeline for the SDSS imaging database using Hadoop. This multi-terabyte imaging dataset provides a good testbed for algorithm development since its scope and structure approximate future surveys. First, we describe MapReduce and how we adapted image coaddition to the MapReduce framework. Then we describe a number of optimizations to our basic approach and report experimental results compring their performance. This work is funded by the NSF and by NASA.

Wiley, Keith; Connolly, A.; Gardner, J.; Krughoff, S.; Balazinska, M.; Howe, B.; Kwon, Y.; Bu, Y.

2011-01-01

90

High resolution (375 m) cloud microstructure as seen from the NPP/VIIRS Satellite imager  

NASA Astrophysics Data System (ADS)

The VIIRS (Visible Infrared Imaging Radiometer Suite) onboard the Suomi NPP (National Polar-Orbiting Partnership) satellite has improved resolution of 750 m with respect to 1000 m of the MODerate-resolution Imaging Spectroradiometer, for the channels that allow retrieving cloud microphysical parameters such as cloud drop effective radius (re). The VIIRS has also an imager with 5 channels of double resolution of 375 m, which was not designed for retrieving cloud products. A methodology for a high resolution retrieval of re and microphysical presentation of the cloud field based on the VIIRS imager was developed and evaluated with respect to MODIS in this study. The tripled microphysical resolution with respect to MODIS allows obtaining new insights for cloud aerosol interactions, especially at the smallest cloud scales, because the VIIRS imager can resolve the small convective elements that are sub-pixel for MODIS cloud products. Examples are given for new insights on ship tracks in marine stratocumulus, pollution tracks from point and diffused sources in stratocumulus and cumulus clouds over land, deep tropical convection in pristine air mass over ocean and land, tropical clouds that develop in smoke from forest fires and in heavy pollution haze over densely populated regions in southeast Asia, and for pyro-cumulonimbus clouds. It is found that the VIIRS imager provides more robust physical interpretation and refined information for cloud and aerosol microphysics as compared to MODIS, especially in the initial stage of cloud formation. VIIRS is found to identify much more full-cloudy pixels when small boundary layer convective elements are present. This, in turn, allows a better quantification of cloud aerosol interactions and impacts on precipitation forming processes.

Rosenfeld, D.; Liu, G.; Yu, X.; Zhu, Y.; Dai, J.; Xu, X.; Yue, Z.

2013-11-01

91

High-resolution (375 m) cloud microstructure as seen from the NPP/VIIRS satellite imager  

NASA Astrophysics Data System (ADS)

VIIRS (Visible Infrared Imaging Radiometer Suite), onboard the Suomi NPP (National Polar-orbiting Partnership) satellite, has an improved resolution of 750 m with respect to the 1000 m of the Moderate Resolution Imaging Spectroradiometer for the channels that allow retrieving cloud microphysical parameters such as cloud drop effective radius (re). VIIRS also has an imager with five channels of double resolution of 375 m, which was not designed for retrieving cloud products. A methodology for a high-resolution retrieval of re and microphysical presentation of the cloud field based on the VIIRS imager was developed and evaluated with respect to MODIS in this study. The tripled microphysical resolution with respect to MODIS allows obtaining new insights for cloud-aerosol interactions, especially at the smallest cloud scales, because the VIIRS imager can resolve the small convective elements that are sub-pixel for MODIS cloud products. Examples are given for new insights into ship tracks in marine stratocumulus, pollution tracks from point and diffused sources in stratocumulus and cumulus clouds over land, deep tropical convection in pristine air mass over ocean and land, tropical clouds that develop in smoke from forest fires and in heavy pollution haze over densely populated regions in southeastern Asia, and for pyro-cumulonimbus clouds. It is found that the VIIRS imager provides more robust physical interpretation and refined information for cloud and aerosol microphysics as compared to MODIS, especially in the initial stage of cloud formation. VIIRS is found to identify significantly more fully cloudy pixels when small boundary layer convective elements are present. This, in turn, allows for a better quantification of cloud-aerosol interactions and impacts on precipitation-forming processes.

Rosenfeld, D.; Liu, G.; Yu, X.; Zhu, Y.; Dai, J.; Xu, X.; Yue, Z.

2014-03-01

92

New cloud free line of sight statistics measured with digital whole sky imagers  

NASA Astrophysics Data System (ADS)

Cloud Free Line of Sight (CFLOS) statistics can be important to a number of applications involving transmittance of light through the atmosphere, including laser propagation, light propagation, and detection of objects by humans and instruments. This paper will discuss Cloud Free Line of Sight (CFLOS) and cloud persistence statistics determined from cloud measurements taken with Whole Sky Imagers (WSI). The WSIs are ground-based digital imaging systems that image the full upper hemisphere down to the horizon in wavebands in the visible and NIR. Digital automated WSI systems were originally developed by the Marine Physical Lab in the 1980's to address the CFLOS application, and then further developed for 24-hour day and night capability. Approximately three million image sets have been acquired with the Day/Night WSI in conjunction with DOE's ARM program. Recent advances in the cloud decision algorithms at Marine Physical Lab have enabled the extraction of processed cloud images of sufficient quality to obtain reliable cloud statistics. A test sample of approximately 4500 image sets has been processed to yield CFLOS statistics down to the horizon, as well as statistics related to the persistence of clouds and cloud holes. This talk will provide a brief overview of the instruments and current algorithm developments. The CFLOS results and sample persistence results will be presented.

Shields, Janet E.; Burden, Art R.; Johnson, Richard W.; Karr, Monette E.; Baker, Justin G.

2005-08-01

93

The effect of image enhancement on biomedical pattern recognition  

Microsoft Academic Search

Image enhancement has been an area of active research for decades. Most studies were aimed at improving the quality of image display for better visualization. Yet few studies have been conducted to investigate the impact of image enhancement on biomedical pattern recognition. In this paper, we examine quantitatively the effect of image enhancement on the performance of biomedical pattern recognition.

Qiang Wut; Yu-Ping Wangt; Zhongmin Liu; Tiehan Chent; K. R. Castleman

2002-01-01

94

Clouds  

NSDL National Science Digital Library

Students learn about the varieties of clouds, what they look like and how they can affect our lives. Introduction: Have you ever wondered what kind of cloud makes rain, or which one makes fog? Have you ever wondered if there are clouds that mean the weather if going to be good or not? Today, we're going to learn about three different clouds that may ...

Doxey, Ms.

2010-03-26

95

The analysis of polar clouds from AVHRR satellite data using pattern recognition techniques  

NASA Technical Reports Server (NTRS)

The cloud cover in a set of summertime and wintertime AVHRR data from the Arctic and Antarctic regions was analyzed using a pattern recognition algorithm. The data were collected by the NOAA-7 satellite on 6 to 13 Jan. and 1 to 7 Jul. 1984 between 60 deg and 90 deg north and south latitude in 5 spectral channels, at the Global Area Coverage (GAC) resolution of approximately 4 km. This data embodied a Polar Cloud Pilot Data Set which was analyzed by a number of research groups as part of a polar cloud algorithm intercomparison study. This study was intended to determine whether the additional information contained in the AVHRR channels (beyond the standard visible and infrared bands on geostationary satellites) could be effectively utilized in cloud algorithms to resolve some of the cloud detection problems caused by low visible and thermal contrasts in the polar regions. The analysis described makes use of a pattern recognition algorithm which estimates the surface and cloud classification, cloud fraction, and surface and cloudy visible (channel 1) albedo and infrared (channel 4) brightness temperatures on a 2.5 x 2.5 deg latitude-longitude grid. In each grid box several spectral and textural features were computed from the calibrated pixel values in the multispectral imagery, then used to classify the region into one of eighteen surface and/or cloud types using the maximum likelihood decision rule. A slightly different version of the algorithm was used for each season and hemisphere because of differences in categories and because of the lack of visible imagery during winter. The classification of the scene is used to specify the optimal AVHRR channel for separating clear and cloudy pixels using a hybrid histogram-spatial coherence method. This method estimates values for cloud fraction, clear and cloudy albedos and brightness temperatures in each grid box. The choice of a class-dependent AVHRR channel allows for better separation of clear and cloudy pixels than does a global choice of a visible and/or infrared threshold. The classification also prevents erroneous estimates of large fractional cloudiness in areas of cloudfree snow and sea ice. The hybrid histogram-spatial coherence technique and the advantages of first classifying a scene in the polar regions are detailed. The complete Polar Cloud Pilot Data Set was analyzed and the results are presented and discussed.

Smith, William L.; Ebert, Elizabeth

1990-01-01

96

Empirical orthogonal function analysis of cloud-containing coastal zone color scanner images of northeastern North American coastal waters  

NASA Technical Reports Server (NTRS)

Empirical-orthogonal-function (EOF) analyses were carried out on 36 images of the Mid-Atlantic Bight and the Gulf of Maine, obtained by the CZCS aboard Nimbus 7 for the time period from February 28 through July 9, 1979, with the purpose of determining pigment concentrations in coastal waters. The EOF procedure was modified so as to include images with significant portions of data missing due to cloud obstruction, making it possible to estimate pigment values in areas beneath clouds. The results of image analyses explained observed variances in pigment concentrations and showed a south-to-north pattern corresponding to an April Mid-Atlantic Bight bloom and a June bloom over Nantucket Shoals and Platts Bank.

Eslinger, David L.; O'Brien, James J.; Iverson, Richard L.

1989-01-01

97

Image pattern recognition supporting interactive analysis and graphical visualization  

NASA Technical Reports Server (NTRS)

Image Pattern Recognition attempts to infer properties of the world from image data. Such capabilities are crucial for making measurements from satellite or telescope images related to Earth and space science problems. Such measurements can be the required product itself, or the measurements can be used as input to a computer graphics system for visualization purposes. At present, the field of image pattern recognition lacks a unified scientific structure for developing and evaluating image pattern recognition applications. The overall goal of this project is to begin developing such a structure. This report summarizes results of a 3-year research effort in image pattern recognition addressing the following three principal aims: (1) to create a software foundation for the research and identify image pattern recognition problems in Earth and space science; (2) to develop image measurement operations based on Artificial Visual Systems; and (3) to develop multiscale image descriptions for use in interactive image analysis.

Coggins, James M.

1992-01-01

98

Quantitative Comparison of Dense Cloud Detection of an Evolutionary Image Classification Algorithm to the MODIS Cloud Mask and to the VIIRS Cloud Mask  

NASA Astrophysics Data System (ADS)

The proper identification of cloud cover plays an important role for the accurate determination of atmospheric and surface parameters from remotely sensed data. The MODIS (Moderate Resolution Imaging Spectroradiometer) cloud mask algorithm has been used by NASA and other governmental agencies as input for models, analysis systems, and decision support tools. The Visible Infrared Imager Radiometer Suite (VIIRS) cloud mask will be an important product for the National Polar-orbiting Operational Environmental Satellite System (NPOESS) and it has been researched as a replacement alternative in many of the existing NASA programs. Among them, the Rapid Prototyping Capability (RPC) project, at the University of Mississippi, investigates the VIIRS data as a replacement for the MODIS data in the SERVIR Decision Support Tool, which uses cloud masks as required inputs. In this project, the performance of these algorithms is compared to the Evolutionary Image Classification Algorithm (EICA). This semi-automated learn-from- examples evolutionary framework was used for dense cloud detection by combining preprocessing functions with standard unsupervised classification algorithms. The preprocessing functions as well as the parameters used in the unsupervised classification step were defined by genetic programming as the evolutionary tool to search for the optimal solution. Genetic programming evolves (iterative trial and error process) preprocessing functions formed by spectral indices built from basic function blocks defined in the function set (arithmetic operations) and in the terminal set (spectral bands). MODIS granules covering Central America were selected at different dates during the fire season to be used as the study site. These granules were manually classified using the first two MODIS channels and were considered as reference data. The cloud mask generated from the evolutionary classification algorithm, the VIIRS cloud mask and the MODIS cloud mask results were then compared using the Kappa statistics as the measurement of success.

Momm, H. G.; Easson, G.

2006-12-01

99

Ultraviolet imaging polarimeter for observing polar mesospheric clouds  

NASA Astrophysics Data System (ADS)

To study the polarization of sunlight scattered from polar mesospheric clouds (PMC) and the Rayleigh scattering from the upper atmosphere, we designed, constructed, and flew an ultraviolet imaging polarimeter (UVIP). A rocket-borne experiment, the UVIP consists of: an f/2 baffled telescope with a focal length of 76 mm; a filter/polarizer wheel with spectral bandpass and UV polarizing filters; a diode image intensifier; a thermoelectrically cooled, self-scanned diode array; and driver-interface electronics. The three polarization measurements are at 265 nm (8 nm spectral bandpass). Also, an unpolarized filter at 190 nm (20 nm bandpass) provides the color ratio 195 nm/265 nm. The Earth's limb is imaged onto the 128 pixels of the detector, observing tangent heights of 40 - 150 km with a height resolution of approximately equals 2 km. Previous optical measurements of PMC ice crystals indicate the particle scattering is Rayleigh-like, suggesting very high polarizations. To measure PMC against the ambient Rayleigh scatter requires 1% precision in polarization. Since we accurately know the polarization of the Rayleigh background, the technique is self-calibrating. We present the design of this instrument and example data from two rocket flights.

Lawrence, George M.; Thomas, Gary E.; Kohnert, Richard A.; Westfall, J.

1994-09-01

100

Investigation of vortex clouds and droplet sizes in heated water spray patterns generated by axisymmetric full cone nozzles.  

PubMed

The hot water sprays are an important part of many industrial processes, where the detailed knowledge of physical phenomena involved in jet transportation, interaction, secondary breakup, evaporation, and coalescence of droplets is important to reach more efficient processes. The objective of the work was to study the water spray jet breakup dynamics, vortex cloud formation, and droplet size distribution under varying temperature and load pressure. Using a high speed camera, the spray patterns generated by axisymmetric full cone nozzles were visualized as a function water temperature and load pressure. The image analysis confirmed that the spray cone angle and width do not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The formation and decay of semitorus like vortex clouds were also noticed in spray structures generated at near water boiling point temperature. For the nozzle with smallest orifice diameter (1.19 mm), these vortex clouds were very clear at 90°C heating temperature and 1 bar water load pressure. In addition, the sauter mean diameter (SMD) of the spray droplets was also measured by using Phase Doppler Anemometry (PDA) at different locations downstream of the nozzle exit. It was noticed that SMD varies slightly w.r.t. position when measured at room temperature whereas at higher temperature values, it became almost constant at distance of 55 mm downstream of the nozzle exit. PMID:24307881

Naz, M Y; Sulaiman, S A; Ariwahjoedi, B; Ku Shaari, Ku Zilati

2013-01-01

101

Investigation of Vortex Clouds and Droplet Sizes in Heated Water Spray Patterns Generated by Axisymmetric Full Cone Nozzles  

PubMed Central

The hot water sprays are an important part of many industrial processes, where the detailed knowledge of physical phenomena involved in jet transportation, interaction, secondary breakup, evaporation, and coalescence of droplets is important to reach more efficient processes. The objective of the work was to study the water spray jet breakup dynamics, vortex cloud formation, and droplet size distribution under varying temperature and load pressure. Using a high speed camera, the spray patterns generated by axisymmetric full cone nozzles were visualized as a function water temperature and load pressure. The image analysis confirmed that the spray cone angle and width do not vary significantly with increasing Reynolds and Weber numbers at early injection phases leading to increased macroscopic spray propagation. The formation and decay of semitorus like vortex clouds were also noticed in spray structures generated at near water boiling point temperature. For the nozzle with smallest orifice diameter (1.19?mm), these vortex clouds were very clear at 90°C heating temperature and 1 bar water load pressure. In addition, the sauter mean diameter (SMD) of the spray droplets was also measured by using Phase Doppler Anemometry (PDA) at different locations downstream of the nozzle exit. It was noticed that SMD varies slightly w.r.t. position when measured at room temperature whereas at higher temperature values, it became almost constant at distance of 55?mm downstream of the nozzle exit.

Naz, M. Y.; Sulaiman, S. A.; Ariwahjoedi, B.; Ku Shaari, Ku Zilati

2013-01-01

102

Haze and cloud cover recognition and removal for serial Landsat images  

NASA Astrophysics Data System (ADS)

In this paper, a optimized algorithm to recognize and remove hazes and clouds from remotely sensed images of Landsat MSS/TM/ETM+ over land has been proposed. This algorithm uses only the image feature to automatically recognize and remove contamination of hazes and clouds which will prevent satellite image from assessing land surface variables. The hazes and clouds can be detected on the base of the reflectance difference with the other regions, likes thermal spectrum region. Based on both fourth tasseled cap parameter and a haze optimized transformation(HOT) as a measure of haze/cloud spatial density for single Landsat MSS/TM/ETM+ image, haze and clouds can be quantitatively recognized and removed. The performance of the proposed algorithm is demonstrated experimentally. This method can be used for atmospheric corrections to improve landscape change detection.

Kong, Xiangsheng; Qian, Yonggang; Zhang, Anding

2011-11-01

103

Automatic Cloud Detection from Multi-Temporal Satellite Images: Towards the Use of PLÉIADES Time Series  

NASA Astrophysics Data System (ADS)

Contrary to aerial images, satellite images are often affected by the presence of clouds. Identifying and removing these clouds is one of the primary steps to perform when processing satellite images, as they may alter subsequent procedures such as atmospheric corrections, DSM production or land cover classification. The main goal of this paper is to present the cloud detection approach, developed at the French Mapping agency. Our approach is based on the availability of multi-temporal satellite images (i.e. time series that generally contain between 5 and 10 images) and is based on a region-growing procedure. Seeds (corresponding to clouds) are firstly extracted through a pixel-to-pixel comparison between the images contained in time series (the presence of a cloud is here assumed to be related to a high variation of reflectance between two images). Clouds are then delineated finely using a dedicated region-growing algorithm. The method, originally designed for panchromatic SPOT5-HRS images, is tested in this paper using time series with 9 multi-temporal satellite images. Our preliminary experiments show the good performances of our method. In a near future, the method will be applied to Pléiades images, acquired during the in-flight commissioning phase of the satellite (launched at the end of 2011). In that context, this is a particular goal of this paper to show to which extent and in which way our method can be adapted to this kind of imagery.

Champion, N.

2012-08-01

104

Mesospheric Clouds on Mars in Nadir-Pointed THEMIS-VIS Images  

NASA Astrophysics Data System (ADS)

We present images of very-high-altitude clouds obtained at near-zero emission angles by the Mars Odyssey spacecraft's Thermal Emission Spectrometer visible subsystem (THEMIS-VIS). Although THEMIS-VIS was not designed or intended for stereo imaging, the parallax effect caused by its multiple exposure color-imaging sequence allows the height of clouds with sufficient spatial contrast to be determined with a precision of 5-10 km. To determine cloud height in a given image, we make an initial guess of the height, reproject the subframes that make up the image onto a surface of that elevation, and then examine the reprojected imagine to determine whether the cloud features are properly aligned in overlapping subframes. This process is repeated until the best fitting elevation is found. The precision of the height estimate obtained in this manner is obviously limited by the sharpness of the cloud features. Although clouds and hazes are common in the THEMIS-VIS data set, images in which a cloud height can be measured are extremely rare. To date, we have only two detections of equatorial high-altitude clouds, both of which occur (possibly coincidentally) over high surface elevations in the eastern Tharsis bulge, but in quite different seasons --- {L} {s} 26o and {L} {s} 114o. In both cases, the detections are in late-afternoon images, near 4:30 PM local solar time, the cloud heights are near 75 km above the local surface, and the cloud structure is wispy and lineated. Our detections are consistent with limb observations by TES (solar band) and MOC (Wide Angle) of high altitude clouds (Clancy et al., 2004, DPS). Clancy et al.~find that these clouds appear to be present only within a very restricted range of longitudes and seasonal intervals. In addition to the equatorial cloud measurements, we have also in a few instances been able to measure heights of 60-70 km for mid-latitude clouds near the fringes of the polar hood in early northern winter. This measurement requires the serendipitous confluence of unusually distinct cloud features and favorable lighting conditions, and so, at this time, it is difficult to assess the prevalence or nature of high altitude clouds in this region and season.

McConnochie, T. H.; Bell, J. F.; Savransky, D.; Wolff, M. J.; Christensen, P. R.

2004-12-01

105

REGISTRATION OF TERRESTRIAL LASER SCANNER POINT CLOUDS BY ONE IMAGE  

Microsoft Academic Search

Registration of point clouds in the same coordinate system is the most important step in processing of terrestrial laser scanner measurements. Used methods for registration of point clouds have required scanned overlap area betweeen point clouds or adequate points for every scan in common coordinate system. These procedures are required time and labor more than necessary. In this study, a

C. Altuntas; F. Yildiz

106

Mesospheric Clouds on Mars in Nadir-Pointed THEMIS-VIS Images  

Microsoft Academic Search

We present images of very-high-altitude clouds obtained at near-zero emission angles by the Mars Odyssey spacecraft's Thermal Emission Spectrometer visible subsystem (THEMIS-VIS). Although THEMIS-VIS was not designed or intended for stereo imaging, the parallax effect caused by its multiple exposure color-imaging sequence allows the height of clouds with sufficient spatial contrast to be determined with a precision of 5-10 km.

T. H. McConnochie; J. F. Bell; D. Savransky; M. J. Wolff; P. R. Christensen

2004-01-01

107

A cloud pattern recognition algorithm to automate the estimation of mass eruption rates from an umbrella cloud or downwind plume observed via satellite imagery  

NASA Astrophysics Data System (ADS)

The eruption of Eyjafjallajökull, Iceland in April and May, 2010, brought to light the importance of Volcanic Ash Transport and Dispersion models (VATD) to the estimation of the position and concentration of ash with time, and how vital it is for Volcanic Ash Advisory Centers (VAACs) to be able to detect and track ash clouds with both observations and models. The VATD needs to get Eruption Source Parameters (ESP), including mass eruption rate through time, as input, which ultimately relies on the detection of the eruption regardless of the meteorological conditions. Volcanic cloud recognition is especially difficult when meteorological clouds are also present, which is typically the case in the tropics. Given the fact that meteorological clouds and volcanic clouds behave differently, we developed an agent-based pattern definition algorithm to detect and define volcanic clouds on satellite imagery. We have combined this with a plume growth rate methodology to automate the estimation of volumetric and mass growth with time using plume geometry provided by satellite imagery. This allows an estimation of the mass eruption rate (MER) with time. To test our approach, we used the examples of two eruptions of different source strength, in two different climatic regimes and for which therefore the weather during eruption was quite different: Grímsvötn (Iceland) May 21, 2011, which produced an umbrella cloud readily seen above the cloud deck, and Manam (Papua New Guinea) October 24, 2004, which produced a stratospheric umbrella cloud that rapidly turned into a downwind plume, and was difficult to distinguish from meteorological clouds. The new methods may in the future allow for fast, easy and automated detection of volcanic clouds as well as a remote assessment of the mass eruption rate with time, even for inaccessible volcanoes. The methods may thus provide an additional path to estimation of the ESP and the forecasting of ash cloud propagation.

Jansons, E.; Pouget, S.; Bursik, M. I.; Patra, A. K.; Pitman, E. B.; Tupper, A.

2013-12-01

108

Memory-Based Forecasting for Weather Image Patterns  

Microsoft Academic Search

A novel method and a framework called Memory-Based Forecasting are proposed to forecast complex and time- varying natural patterns with the goal of supporting ex- perts' decision making. This paper targets the local precipitation phenomena captured as echo patterns in weather radar images, and aims to realize a tool that supports weather forecasters. In our framework, past image patterns similar

Kazuhiro Otsuka; Tsutomu Horikoshi; Satoshi Suzuki; Haruhiko Kojima

2000-01-01

109

Interactive 3D modeling based on point-clouds with reflectance image  

Microsoft Academic Search

Mid-range and long-range laser scanners can capture dense point-clouds of indoor and outdoor environment. However, such point-clouds are measured only from a few sides and large portions of the data are missing. In this paper, we propose a method for generating 3D models from incomplete point-clouds by applying image-based modeling techniques, since recent laser scanners can output the reflectance value

Nozomi Kanata; Satoshi Fujii; Hiroshi Masuda

2009-01-01

110

3D INDUSTRIAL RECONSTRUCTION BY FITTING CSG MODELS TO A COMBINATION OF IMAGES AND POINT CLOUDS  

Microsoft Academic Search

We present a method for 3D reconstruction of industrial sites using a combination of images and point clouds with a motivation of achieving higher levels of automation, precision, and reliability. Recent advances in 3D scanning technologies have made possible rapid and cost-effective acquisition of dense point clouds for 3D reconstruction. As the point clouds provide explicit 3D information, they have

Tahir Rabbani; Frank van den Heuvel

111

Accuracy assessment of building point clouds automatically generated from iphone images  

NASA Astrophysics Data System (ADS)

Low-cost sensor generated 3D models can be useful for quick 3D urban model updating, yet the quality of the models is questionable. In this article, we evaluate the reliability of an automatic point cloud generation method using multi-view iPhone images or an iPhone video file as an input. We register such automatically generated point cloud on a TLS point cloud of the same object to discuss accuracy, advantages and limitations of the iPhone generated point clouds. For the chosen example showcase, we have classified 1.23% of the iPhone point cloud points as outliers, and calculated the mean of the point to point distances to the TLS point cloud as 0.11 m. Since a TLS point cloud might also include measurement errors and noise, we computed local noise values for the point clouds from both sources. Mean (?) and standard deviation (?) of roughness histograms are calculated as (?1 = 0.44 m., ?1 = 0.071 m.) and (?2 = 0.025 m., ?2 = 0.037 m.) for the iPhone and TLS point clouds respectively. Our experimental results indicate possible usage of the proposed automatic 3D model generation framework for 3D urban map updating, fusion and detail enhancing, quick and real-time change detection purposes. However, further insights should be obtained first on the circumstances that are needed to guarantee a successful point cloud generation from smartphone images.

Sirmacek, B.; Lindenbergh, R.

2014-06-01

112

Discrete plane segmentation and estimation from a point cloud using local geometric patterns  

Microsoft Academic Search

This paper presents a method for segmenting a 3D point cloud into planar surfaces using recently obtained discrete-geometry\\u000a results. In discrete geometry, a discrete plane is defined as a set of grid points lying between two parallel planes with\\u000a a small distance, called thickness. In contrast to the continuous case, there exist a finite number of local geometric patterns\\u000a (LGPs)

Yukiko Kenmochi; Lilian Buzer; Akihiro Sugimoto; Ikuko Shimizu

2008-01-01

113

Global Images of Polar Mesospheric Clouds From the SNOE Spacecraft  

NASA Astrophysics Data System (ADS)

Polar Mesospheric Clouds (PMC) have been observed from several spacecraft over the last three decades. These experiments have shown the seasonal behavior of PMCs and have provided some morphological information. The Student Nitric Oxide Explorer (SNOE) has been observing PMCs since 1998 and has successfully measured six PMC seasons. SNOE is a spinning satellite in a sun-synchronous near-polar orbit at 10:30 am/pm local time. SNOE has a significant advantage over its predecessors in that it is able to observe PMCs globally each day. In the summer seasons, the Ultraviolet Spectrometer (UVS) limb measurements include detections of PMCs around 83 km. Because SNOE orbits the earth 15 times a day, it obtains global coverage of the mesosphere. By combining the 15 orbits, we can produce daily global images of PMC observation frequency and UV scattering ratio. The SNOE measurements show that PMCs start to form at high latitudes (75 degrees and higher) in the beginning of the PMC season, three weeks before summer solstice. By the middle of the season, PMCs form globally down to 50 degrees in latitude and then recede back to higher latitudes in the latter part of the season. The daily images, shown in a movie format, show the day-to-day variability in latitude and longitude of the PMC occurrences. The images suggest the influence of dynamics on the creation and destruction of PMCs. Case studies of several 5-10 day periods show a westward movement of PMC formation with the suggestion of wave structure.

Merkel, A. W.; Thomas, G. E.; Bailey, S. M.; Barth, C. A.

2001-05-01

114

A method of improving structured light scanning point cloud using stereo image processing  

Microsoft Academic Search

Main defect of the structured light scanning is that the edge part is lost in the point clouds of scanned object. This research tried to combine the image processing method to a structured light system in order to improve the quality of the point cloud. The technique approaches are present, and the results are given as below: after overlying the

Ruoming Shi; Yong Yu; Ling Zhu

2011-01-01

115

Scale Matching of 3D Point Clouds by Finding Keyscales with Spin Images  

Microsoft Academic Search

In this paper we propose a method for matching the scales of 3D point clouds. 3D point sets of the same scene obtained by 3D reconstruction techniques usually differ in scales. To match scales, we propose a keyscale that characterizes the scale of a given 3D point cloud. By performing PCA of spin images over different scales, a keyscale is

Toru Tamaki; Shunsuke Tanigawa; Yuji Ueno; Bisser Raytchev; Kazufumi Kaneda

2010-01-01

116

Images of Hurricane Katrina (2005) below the cloud  

NASA Astrophysics Data System (ADS)

A remarkable coincidence of two independent satellite images from Radarsat-1 synthetic aperture radar (SAR) and SeaWinds/QuikSCAT scatterometer, depicting the state of the sea surface, and HRD/NOAA aircraft reconnaissance including a Stepped Frequency Microwave Radiometer (SFMR), occurred in Hurricane Katrina near the time of its maximum intensity on August 28th, 2005. The satellite images were acquired within 6 seconds of each other near 2345 UTC. The eye, primary and secondary eyewalls, and outer rainbands were traversed by the aircraft during the time of image acquisition, and all of these features are visible on the images, both of which captured most of the storm area. Comparison of SAR and scatterometer images indicates good agreement in the level of backscatter pixel-by-pixel when SAR pixels (~50 m) are averaged to match scatterometer pixels (~2.5 km). Comparison with airborne SFMR also indicates good agreement when the aircraft data are rotated slightly in azimuth to account for advection by the tangential surface winds over a period of 0-6 minutes. Seven independent measurements of horizontal wind are available in this unique situation: one from each satellite image, the airborne radiometer, in situ flight-level data, dropsondes, fuselage radar (for feature tracking of precipitation features) and tail Doppler radar (a 3D wind field synthesized over ~1 hour). Comparison of surface and flight level data in the primary eyewall indicates an outward tilt of the axis of maximum winds with height similar to that seen in the Doppler composite structure obtained around this time. Surface winds appear stronger than flight-level winds in the primary eyewall but not in a secondary eyewall farther out.. Tangential wind maxima are associated with both eyewalls -- each a ring of enhanced precipitation -- and both are superposed on a radial profile of rather strong winds, suggesting that significant microwave backscatter should be expected throughout the inner core, as observed. Nevertheless, the imprint of eye and eyewalls on the sea surface is clearly visible in the satellite backscatter images and in surface winds derived from their respective retrieval algorithms. Our coincidence of independent wind measurements provides an unprecedented opportunity for algorithm validation in an extreme wind/rainfall environment and to assess the impacts, if any, of cloud liquid water and raindrops on beam attenuation in the C and Ku bands used, respectively, by the SAR and scatterometer. A few suspiciously dark features in an outer rainband are detected in both satellite images, and an attempt is made to collocate with spots of maximum precipitation in a sequence of fuselage radar images in order to address this issue. Similar features are sometimes seen in SAR images of other hurricanes, suggesting small pockets or "seams" of relative calm. Comments are made on the utility of SAR imagery for ocean swell and sea spray in the hurricane inner-core environment, and for depiction of convective downdrafts in the outer bands.

Dunkerton, T. J.; Walter, B. A.; Perrie, W.; Long, D. G.; Zhang, J.; Black, P. G.; Rogers, R.

2006-12-01

117

Weekly cycle of lightning and associated patterns of rainfall, cloud, and aerosols over Korea and adjacent oceans during boreal summer  

NASA Astrophysics Data System (ADS)

In this study, we analyze the weekly cycle of lightning over Korea and adjacent oceans and associated variations of aerosols, clouds, precipitation, and atmospheric circulations, using aerosol optical depth (AOD) from the NASA Moderate resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR), cloud properties from MODIS, precipitation and storm height from Tropical Rainfall Measuring Mission (TRMM) satellite, and lightning data from the Korean Lightning Detection Network (KLDN) during 9-year from 2002 to 2010. Lightning data was divided into three approximately equal areas, land area of Korea, and two adjacent oceans, Yellow Sea and South Sea. Preliminary results show that the number of lightning increases during the middle of the week over land area. AOD data also shows moderately significant midweek increase at about the same time as lightning peaks. These results are consistent with the recent studies showing the invigoration of storms with more ice hydrometeors by aerosols, and subsequently wash out of aerosols by rainfall. Frequency of lightning strokes tend to peak at weekend in coastal area and over South Sea, indicating local weekly anomalous circulation between land and adjacent ocean. On the other hand, lightning frequency over Yellow Sea appears to have very strong weekly cycle with midweek peak on around Wednesday. It is speculated that the midweek peak of lightning over Yellow Sea was related with aerosol transport from adjacent land area. AOD data also suggests midweek peak over Yellow Sea, however, the weekly cycle of AOD was not statistically significant. Changes in weekly cycle of lightning from pre-monsoon to monsoon season, as well as associated clouds and circulation patterns are also discussed.

Kim, J.; Kim, K.

2011-12-01

118

Weekly Cycle of Lightning and Associated Patterns of Rainfall, Cloud, and Aerosols over Korea and Adjacent Oceans during Boreal Summer  

NASA Technical Reports Server (NTRS)

In this study, we analyze the weekly cycle of lightning over Korea and adjacent oceans and associated variations of aerosols, clouds, precipitation, and atmospheric circulations, using aerosol optical depth (AOD) from the NASA Moderate resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR), cloud properties from MODIS, precipitation and storm height from Tropical Rainfall Measuring Mission (TRMM) satellite, and lightning data from the Korean Lightning Detection Network (KLDN) during 9-year from 2002 to 2010. Lightning data was divided into three approximately equal areas, land area of Korea, and two adjacent oceans, Yellow Sea and South Sea. Preliminary results show that the number of lightning increases during the middle of the week over Yellow Sea. AOD data also shows moderately significant midweek increase at about the same time as lightning peaks. These results are consistent with the recent studies showing the invigoration of storms with more ice hydrometeors by aerosols, and subsequently wash out of aerosols by rainfall. Frequency of lightning strokes tend to peak at weekend in land area and over South Sea, indicating local weekly anomalous circulation between land and adjacent ocean. On the other hand, lightning frequency over Yellow Sea appears to have very strong weekly cycle with midweek peak on around Wednesday. It is speculated that the midweek peak of lightning over Yellow Sea was related with aerosol transport from adjacent land area. AOD data also suggests midweek peak over Yellow Sea, however, the weekly cycle of AOD was not statistically significant. Changes in weekly cycle of lightning from pre-monsoon to monsoon season, as well as associated clouds and circulation patterns are also discussed.

Kim, Ji-In; Kim, Kyu-Myong

2011-01-01

119

Complex Clouds  

article title:  Multi-layer Clouds Over the South Indian Ocean     ... Larger Image The complex structure and beauty of polar clouds are highlighted by these images acquired by the Multi-angle Imaging ...

2013-04-16

120

Characterization of mesoscale gravity waves in the upper and lower clouds of Venus from VEX-VIRTIS images  

Microsoft Academic Search

Images obtained from the Visible and InfraRed Thermal Imaging Spectrometer (VIRTIS)-M instrument onboard Venus Express present visible trains of alternating bands of cloud brightness in two different layers: at the upper cloud tops (?66 km altitude) observed in the dayside hemisphere using reflected ultraviolet light (380 nm) and in the lower cloud (?47 km altitude) observed in the nightside hemisphere

J. Peralta; R. Hueso; A. Sánchez-Lavega; G. Piccioni; O. Lanciano; P. Drossart

2008-01-01

121

Near and Far Infrared Imaging for Vein Pattern Biometrics  

Microsoft Academic Search

This paper investigates two infrared imaging technologies, far-infrared thermography and near-infrared imaging, to acquire hand vein pattern images for biometric purposes. The imaging principles for both technologies are studied in depth. Experiments involving data acquisition from various parts of hand, including the back of the hand, palm, and wrist are described using a population of 150 participants using both near

Lingyu Wang; Graham Leedham

2006-01-01

122

Satellite retrieval of convective cloud base temperature based on the NPP/VIIRS Imager  

NASA Astrophysics Data System (ADS)

advent of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-Orbiting Partnership (NPP) satellite provided a quantum jump in the satellite capabilities of retrieving cloud properties, because it nearly tripled the resolution in the thermal channels (375 m). This allowed us to develop a methodology for retrieving convective cloud base temperature (Tb) and validate it over the Atmospheric System Research Southern Great Plains site for the satellite early afternoon overpass time. The standard error of the Tb retrieval was only 1.1°C. The knowledge of Tb allows the calculation of cloud base height and the depth of the boundary layer, as well as the boundary layer water vapor mixing ratio with an accuracy of about 10%. The feasibility of retrieving cloud base temperature and height is an essential component that is required for retrieving cloud condensation nuclei (CCN) from satellites by using convective clouds as natural CCN chambers.

Zhu, Yannian; Rosenfeld, Daniel; Yu, Xing; Liu, Guihua; Dai, Jin; Xu, Xiaohong

2014-02-01

123

Advanced infrared sounder subpixel cloud detection with imagers and its impact on radiance assimilation in NWP  

NASA Astrophysics Data System (ADS)

cloud detection is very important for infrared (IR) radiance assimilation; improved cloud detection could reduce cloud contamination and hence improve the assimilation. Although operational numerical weather prediction (NWP) centers are using IR sounder radiance data for cloud detection, collocated high spatial resolution imager data could help sounder subpixel cloud detection and characterization. IR sounder radiances with improved cloud detection using Atmospheric Infrared Sounder (AIRS)/Moderate Resolution Imaging Spectroradiometer (MODIS) were assimilated for Hurricane Sandy (2012). Forecast experiments were run with Weather Research and Forecasting (WRF) as the forecast model and the Three-Dimensional Variational Assimilation (3DVAR)-based Gridpoint Statistical Interpolation (GSI) as the analysis system. Results indicate that forecasts of both hurricane track and intensity are substantially improved when the collocated high spatial resolution MODIS cloud mask is used for AIRS subpixel cloud detection for assimilating radiances. This methodology can be applied to process Crosstrack Infrared Sounder (CRIS)/Visible Infrared Imaging Radiometer Suite (VIIRS) onboard Suomi-NPOESS Preparatory Project (NPP)/Joint Polar Satellite System (JPSS) and Infrared Atmospheric Sounding Interferometer (IASI)/Advanced Very High Resolution Radiometer (AVHRR) onboard the Metop series for improved radiance assimilation in NWP.

Wang, Pei; Li, Jun; Li, Jinlong; Li, Zhenglong; Schmit, Timothy J.; Bai, Wenguang

2014-03-01

124

Temporally and spatially resolved imaging of laser-nucleated bubble cloud sonoluminescence.  

PubMed

Imaging techniques have been used to capture the temporal and spatial evolution of light emissions from collapsing bubble clouds at high static pressures. Emission events lasting up to 70 ns with peak diameters nearing 1 mm have been observed. Observations of the cloud evolution before and after emission events have been made. Photomultiplier tube monitoring has been employed in conjunction with imaging to study the temporal characteristics of light emission. PMID:23004893

Sukovich, Jonathan R; Sampathkumar, Ashwin; Anderson, Phillip A; Holt, R Glynn; Pishchalnikov, Yuri A; Gaitan, D Felipe

2012-05-01

125

Temporally and spatially resolved imaging of laser-nucleated bubble cloud sonoluminescence  

NASA Astrophysics Data System (ADS)

Imaging techniques have been used to capture the temporal and spatial evolution of light emissions from collapsing bubble clouds at high static pressures. Emission events lasting up to 70 ns with peak diameters nearing 1 mm have been observed. Observations of the cloud evolution before and after emission events have been made. Photomultiplier tube monitoring has been employed in conjunction with imaging to study the temporal characteristics of light emission.

Sukovich, Jonathan R.; Sampathkumar, Ashwin; Anderson, Phillip A.; Holt, R. Glynn; Pishchalnikov, Yuri A.; Gaitan, D. Felipe

2012-05-01

126

Precise Registration of Point Clouds for Projected Fringe Image  

Microsoft Academic Search

An object has to be measured to recover its 3D shape in reverse engineering applications. The object surface is sampled point by point using a fringe projection to obtain point clouds. Inheriting and optimizing algorithm is proposed to complete precise registration of point clouds. A mathematical model is established to obtain the required transformation parameters. The realizing procedure of the

Meng Fanwen; Wu Lushen; Luo Liping

2009-01-01

127

The identification of cloud types in LANDSAT MSS images. [Great Britain  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. Five general families of clouds were identified: cumulonimbiform, cumuliform, stratiform, stratocumuliform, and cirriform. Four members of this five-fold primary division of clouds were further divided into a number of subgroups. The MSS observed and recorded earth radiation in four different wavebands. Two of these bands (4 and 5) image in the visible portion of the electromagnetic spectrum, while the others (6 and 7) image the short wave portion, or just into the infrared. The main differences between the appearances of clouds in the four wavebands are related to the background brightness of land and sea surfaces.

Barrett, E. C. (principal investigator); Grant, C. K.

1976-01-01

128

Analysis of dust cloud combustion using FAST Infrared Imaging  

NASA Astrophysics Data System (ADS)

Dust cloud combustion is unfortunately at risk in many working environments, jeopardizing several workers. The heat and shock waves resulting from the flame propagation into the dust cloud are harmful and lead to major endangerment or casualties. More precisely, dust cloud (small particles) explosions are even more malicious since they often result from ordinary materials such as coal, flour or pollen. Also, many metal powdered (such as aluminum oxide and magnesium) can form dangerous dust cloud when they are in suspensions in air. The understanding of this particular type of combustion is critical for the preventive care of sites and workers afflicted to such conditions. This paper presents the results of a dynamic flow analysis of metal particles combustion in a dust cloud. The ignition points, the flow rate as well as the propagation direction of the flow have been characterized using fast infrared imagery.

Marcotte, Frederick; Farley, Vincent; Savary, Simon

2013-05-01

129

Estimation of cloud optical thickness by processing SEVIRI images and implementing a semi analytical cloud property retrieval algorithm  

NASA Astrophysics Data System (ADS)

Clouds play a very important role in the Earth's climate system, as they form an intermediate layer between Sun and the Earth. Satellite remote sensing systems are the only means to provide information about clouds on large scales. The geostationary satellite, Meteosat Second Generation (MSG) has onboard an imaging radiometer, the Spinning Enhanced Visible and Infrared Imager (SEVIRI). SEVIRI is a 12 channel imager, with 11 channels observing the earth's full disk with a temporal resolution of 15 min and spatial resolution of 3 km at nadir, and a high resolution visible (HRV) channel. The visible channels (0.6 µm and 0.81 µm) and near infrared channel (1.6µm) of SEVIRI are being used to retrieve the cloud optical thickness (COT). The study domain is over Europe covering the region between 35°N - 70°N and 10°W - 30°E. SEVIRI level 1.5 images over this domain are being acquired from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) archive. The processing of this imagery, involves a number of steps before estimating the COT. The steps involved in pre-processing are as follows. First, the digital count number is acquired from the imagery. Image geo-coding is performed in order to relate the pixel positions to the corresponding longitude and latitude. Solar zenith angle is determined as a function of latitude and time. The radiometric conversion is done using the values of offsets and slopes of each band. The values of radiance obtained are then used to calculate the reflectance for channels in the visible spectrum using the information of solar zenith angle. An attempt is made to estimate the COT from the observed radiances. A semi analytical algorithm [Kokhanovsky et al., 2003] is implemented for the estimation of cloud optical thickness from the visible spectrum of light intensity reflected from clouds. The asymptotical solution of the radiative transfer equation, for clouds with large optical thickness, is the basis of this algorithm. The two visible channels of SEVIRI are used to find the COT and the near infra red channel to estimate the effective radius of droplets. Estimation of COT using a semi analytical scheme, which doesn't involve the conventional look-up table approach, is the aim of this work and henceforth, vertically integrated liquid water (w) or ice water content will be retrieved. The COT estimated and w obtained, will be compared with the values obtained from other approaches and will be validated with in situ measurements. Corresponding author address: Praveen Pandey, VITO - Flemish Institute for Technological Research, Boeretang 200, B 2400, Mol, Belgium. E-mail: praveen.pandey@vito.be

Pandey, P.; De Ridder, K.; van Lipzig, N.

2009-04-01

130

The Log-polar Image Representation in Pattern Recognition Tasks  

Microsoft Academic Search

This paper is a review of works about the use of the log- polar image model for pattern recognition purposes. Particular attention is paid to the rotation-and scale- invariant pattern recognition problem, which is simplified by the log-polar mapping. In spite of this advantage, ordinary translations become a complicated image transform in the log- polar domain. Two approaches addressing the

V. Javier Traver; Filiberto Pla

2003-01-01

131

Study of optimal subset size in digital image correlation of speckle pattern images  

Microsoft Academic Search

This paper investigates the effect of subset size, associated with image pattern quality and subset displacement functions, on the accuracy of deformation measurements by digital image correlation(DIC). A concept of subset entropy is introduced in this work to quantify the subset image pattern quality for DIC analysis and its effectiveness was demonstrated by experimental studies. By employing white-light images with

Sun Yaofeng; John H. L. Pang

2007-01-01

132

Monitoring and automatic detection of the cold-ring patterns atop deep convective clouds using Meteosat data  

NASA Astrophysics Data System (ADS)

This paper presents a newly established database of deep convective storms that exhibit a cold ring at their cloud top, as observed in enhanced infrared (IR) window satellite imagery. The database consists of cold-ring patterns as seen on the Meteosat data over the summer period between 2006 and 2010 for Slovenia and parts of Italy, Austria, Hungary and Croatia. It includes 139 cold rings at different stages, where typically large hail was reported on the ground and as such it serves as an important source of information for any quantitative analysis of the cold rings in this region. The typical characteristics of cold rings in this database are presented and discussed. It was found that the median of the difference between the minimum brightness temperature in the cold ring and the maximum brightness temperature in the central warm spot is 7.1 K, and that the median distance between such pair is 27 km. In addition, the paper presents in detail a new objective satellite-based method for cold-ring or cold-U/V pattern detection on storm tops in infrared imagery. This method uses a combination of infrared brightness temperature from the Meteosat Spinning Enhanced Visible and Infrared Imager (SEVIRI) and the tropopause temperatures from radiosonde measurements. The method was built and evaluated on the cold-ring patterns from the presented database.

Žibert, Mateja Irši?; Žibert, Janez

2013-04-01

133

Cloud Remote Sensing with Sideways-Looks : Theory and First Results Using Multispectral Thermal Imager Data  

SciTech Connect

In operational remote sensing, the implicit model for cloud geometry is a homogeneous plane-parallel slab of infinite horizontal extent. Each pixel is indeed processed as if it exchanged no radiant energy whatsoever with its neighbors. The shortcomings of this conceptual model have been well documented in the specialized literature but rarely mitigated. The worst-case scenario is probably high-resolution imagery where dense isolated clouds are visible, often both bright (reflective) and dark (transmissive) sides being apparent from the same satellite viewing angle: the low transmitted radiance could conceivably be interpreted in plane-parallel theory as no cloud at all. An alternative to the plane-parallel cloud model is introduced here that has the same appeal of being analytically tractable, at least in the diffusion limit: the spherical cloud. This new geometrical paradigm is applied to radiances from cumulus clouds captured by DOE's Multispectral Thermal Imager (MTI). Estimates of isolated cloud opacities are a necessary first step in correcting radiances from surface targets that are visible in the midst of a broken-cloud field. This type of advanced atmospheric correction is badly needed in remote sensing applications such as nonproliferation detection were waiting for a cloud-free look in the indefinite future is not a viable option.

Davis, A. B. (Anthony B.)

2002-01-01

134

Space radar image of Western Pacific rain clouds  

NASA Technical Reports Server (NTRS)

This radar image shows the ocean surface in a portion of the Western Pacific Ocean. Scientists are using images like this to study the occurrence, distribution and activity of tropical rain squalls and to understand the exchange of heat between the atmosphere and ocean and the upper layer mixing in the tropical oceans, which are critical factors for understanding the driving forces which produce the El Nino phenomenon. The white, curved area at the top of the image is a portion of the Ontong Java Atoll, part of the Solomon Islands group. The yellowish green area near the bottom of the image is an intense rain cell. This image is centered near 5.5 degrees South latitude and 159.5 degrees East longitude. The area shown is 50 kilometers by 21 kilometers (31 miles by 13 miles). This image was acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) aboard the space shuttle Endeavour on its 13th orbit on April 10, 1994. The colors in the image are assigned to different frequencies and polarizations of the SIR-C radar as follows: Red is C-band horizontally transmitted and received; green is L-band horizontally transmitted and vertically received and blue is L-band horizontally transmitted and received. The large rain cell is about 15 kilometers by 15 kilometers (9 miles by 9 miles) and contains two dark regions, one circular and one rectangular, inside it. Two smaller reddish cells are visible closer to the atoll. The red areas may be caused by reflection from ice particles in the colder, upper portion of the storm cell and not from the ocean surface at all. This provides direct evidence that it is raining within this storm cell, valuable information which is usually very difficult to measure over more remote regions of the ocean away from coastal-based weather systems. The dark holes in the middle of the cell are thought to be areas of very heavy rainfall which actually smooth out the ocean surface and result in lower radar returns. The surrounding ocean is blue to green plus black. Winds and currents cause the ocean surface to be rough and those variations on the surface affect how the radar signals bounce off the surface. The bright areas on the image correspond to areas where the wind speed is high. The highest winds are seen as the yellow-green region of the large rain cell. The lowest winds are seen inside the atoll as dark areas. Outside the rain cell, the winds are moderately low, which is indicated by the puff-like, blue patterns surrounding the cell and extending into the atoll. The long, thin, dark lines extending across the ocean are surface currents. Here the currents are likely accumulating natural oils caused by small marine biological organisms. The oils cause the small, wind-generated waves to be reduced in size or damped which produces a smooth, dark zone on the radar image.

1995-01-01

135

Imaging Sensor Constellation for Tomographic Chemical Cloud Mapping.  

National Technical Information Service (NTIS)

A sensor constellation capable of determining the location and detailed concentration distribution of chemical warfare agent simulant clouds has been developed and demonstrated on government test ranges. The constellation is based on the use of standoff p...

A. Faghfouri B. R. Cosofret C. M. Gittins D. Konno H. S. Kindle

2009-01-01

136

Electronic speckle pattern interferometry using digital image processing techniques  

Microsoft Academic Search

An application of digital image processing techniques to electronic speckle pattern interferometry (ESPI) is described. A special digital facility with a large frame memory for processing a TV image is developed, allowing one to perform precise and flexible operations such as subtraction, summation, and level slicing. As compared to analog techniques, digital image processing techniques facilitate the generation of high

Suezou Nakadate; Toyohiko Yatagai; Hiroyoshi Saito

1980-01-01

137

Clouds near Phlegra Montes  

NASA Technical Reports Server (NTRS)

14 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle red image shows mid-winter, afternoon cloud patterns over the northern end of the Phlegra Montes near 46oN, 192oW. The image, acquired in December 2003, covers an area approximately 579 km (354 mi) wide; sunlight illuminates the scene from the lower left.

2004-01-01

138

Pattern Recognition Software and Techniques for Biological Image Analysis  

PubMed Central

The increasing prevalence of automated image acquisition systems is enabling new types of microscopy experiments that generate large image datasets. However, there is a perceived lack of robust image analysis systems required to process these diverse datasets. Most automated image analysis systems are tailored for specific types of microscopy, contrast methods, probes, and even cell types. This imposes significant constraints on experimental design, limiting their application to the narrow set of imaging methods for which they were designed. One of the approaches to address these limitations is pattern recognition, which was originally developed for remote sensing, and is increasingly being applied to the biology domain. This approach relies on training a computer to recognize patterns in images rather than developing algorithms or tuning parameters for specific image processing tasks. The generality of this approach promises to enable data mining in extensive image repositories, and provide objective and quantitative imaging assays for routine use. Here, we provide a brief overview of the technologies behind pattern recognition and its use in computer vision for biological and biomedical imaging. We list available software tools that can be used by biologists and suggest practical experimental considerations to make the best use of pattern recognition techniques for imaging assays.

Shamir, Lior; Delaney, John D.; Orlov, Nikita; Eckley, D. Mark; Goldberg, Ilya G.

2010-01-01

139

Satellite approach based on cloud cover classification: Estimation of hourly global solar radiation from meteosat images  

Microsoft Academic Search

Hourly global solar irradiation data useful for the design of solar energy conversion systems is generated using a new satellite based model called SICIC (solar irradiation from cloud image classification). It is a model built by processing high resolution visible Meteosat images and ground measurements of solar radiation flux collected in various locations of France during the 1994\\/95 period. Taking

A. Mefti; A. Adane; M. Y. Bouroubi

2008-01-01

140

Development of an unbiased cloud detection algorithm for a spaceborne multispectral imager  

NASA Astrophysics Data System (ADS)

A new concept for cloud detection from observations by multispectral spaceborne imagers is proposed, and an algorithm comprising many pixel-by-pixel threshold tests is developed. Since in nature the thickness of clouds tends to vary continuously and the border between cloud and clear sky is thus vague, it is unrealistic to label pixels as either cloudy or clear sky. Instead, the extraction of ambiguous areas is considered to be useful and informative. We refer to the multiple threshold method employed in the MOD35 algorithm that is used for Moderate Resolution Imaging Spectroradiometer (MODIS) standard data analysis, but drastically reconstruct the structure of the algorithm to meet our aim of sustaining the neutral position. The concept of a clear confidence level, which represents certainty of the clear or cloud condition, is applied to design a neutral cloud detection algorithm that is not biased to either clear or cloudy. The use of the clear confidence level with neutral position also makes our algorithm structure very simple. Several examples of cloud detection from satellite data are tested using our algorithm and are validated by visual inspection and comparison to previous cloud mask data. The results indicate that our algorithm is capable of reasonable discrimination between cloudy and clear-sky areas over ocean with and without Sun glint, forest, and desert, and is able to extract areas with ambiguous cloudiness condition.

Ishida, Haruma; Nakajima, Takashi Y.

2009-04-01

141

Diurnal, Seasonal, and Interannual Variations of Cloud Properties Derived for CERES From Imager Data  

NASA Technical Reports Server (NTRS)

Simultaneous measurement of the radiation and cloud fields on a global basis is a key component in the effort to understand and model the interaction between clouds and radiation at the top of the atmosphere, at the surface, and within the atmosphere. The NASA Clouds and Earth s Radiant Energy System (CERES) Project, begun in 1998, is meeting this need. Broadband shortwave (SW) and longwave radiance measurements taken by the CERES scanners at resolutions between 10 and 20 km on the Tropical Rainfall Measuring Mission (TRMM), Terra, and Aqua satellites are matched to simultaneous retrievals of cloud height, phase, particle size, water path, and optical depth OD from the TRMM Visible Infrared Scanner (VIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua. Besides aiding the interpretation of the broadband radiances, the CERES cloud properties are valuable for understanding cloud variations at a variety of scales. In this paper, the resulting CERES cloud data taken to date are averaged at several temporal scales to examine the temporal and spatial variability of the cloud properties on a global scale at a 1 resolution.

Minnis, Patrick; Young, David F.; Sun-Mack, Sunny; Trepte, Qing Z.; Chen, Yan; Brown, Richard R.; Gibson, Sharon; Heck, Patrick W.

2004-01-01

142

Images of Schools and Patterns of Change.  

ERIC Educational Resources Information Center

Contrasts the bureaucratic image of schools with four other possible images based on characteristics of social action in sects, legislatures, hospitals, and under anarchic conditions. Aims at developing a greater variety of ways to think about how schools can be organized. Various educational problems and means to resolve them are considered…

Firestone, William A.

1980-01-01

143

Wide-angle imaging LIDAR (WAIL): a ground-based instrument for monitoring the thickness and density of optically thick clouds.  

SciTech Connect

Traditional lidar provides little information on dense clouds beyond the range to their base (ceilometry), due to their extreme opacity. At most optical wavelengths, however, laser photons are not absorbed but merely scattered out of the beam, and thus eventually escape the cloud via multiple scattering, producing distinctive extended space- and time-dependent patterns which are, in essence, the cloud's radiative Green functions. These Green functions, essentially 'movies' of the time evolution of the spatial distribution of escaping light, are the primary data products of a new type of lidar: Wide Angle Imaging Lidar (WAIL). WAIL data can be used to infer both optical depth and physical thickness of clouds, and hence the cloud liquid water content. The instrumental challenge is to accommodate a radiance field varying over many orders of magnitude and changing over widely varying time-scales. Our implementation uses a high-speed microchannel plate/crossed delay line imaging detector system with a 60-degree full-angle field of view, and a 532 nm doubled Nd:YAG laser. Nighttime field experiments testing various solutions to this problem show excellent agreement with diffusion theory, and retrievals yield plausible values for the optical and geometrical parameters of the observed cloud decks.

Love, Steven P.; Davis, A. B. (Anthony B.); Rohde, C. A. (Charles A.); Ho, Cheng,

2001-01-01

144

Cloud detection and classification with the use of whole-sky ground-based images  

NASA Astrophysics Data System (ADS)

A simple whole sky imaging system, based on a commercial digital camera with a fish-eye lens and a hemispheric dome, is used for the automatic estimation of total cloud coverage and classification. For the first time, a multi color criterion is applied on sky images, in order to improve the accuracy in detection of broken and overcast clouds under large solar zenith angles. The performance of the cloud detection algorithm is successfully compared with ground based weather observations. A simple method is presented for the detection of raindrops standing on the perimeter of hemispheric dome. Based on previous works on cloud classification, an improved k-Nearest-Neighbor algorithm is presented, based not only on statistical color and textural features, but taking also into account the solar zenith angle, the cloud coverage, the visible fraction of solar disk and the existence of raindrops in sky images. The successful detection percentage of the classifier ranges between 78 and 95% for seven cloud types.

Kazantzidis, A.; Tzoumanikas, P.; Bais, A. F.; Fotopoulos, S.; Economou, G.

2012-09-01

145

Optical Imaging of Flow Pattern and Phantom  

NASA Technical Reports Server (NTRS)

Time-resolved optical imaging technique has been used to image the spatial distribution of small droplets and jet sprays in a highly scattering environment. The snake and ballistic components of the transmitted pulse are less scattered, and contain direct information about the sample to facilitate image formation as opposed to the diffusive components which are due to multiple collisions as a light pulse propagates through a scattering medium. In a time-gated imaging scheme, these early-arriving, image-bearing components of the incident pulse are selected by opening a gate for an ultrashort period of time and a shadowgram image is detected. Using a single shot cooled CCD camera system, the formation of water droplets is monitored as a function of time. Picosecond time-gated image of drop in scattering cells, spray droplets as a function of let speed and gas pressure, and model calcification samples consisted of calcium carbonate particles of irregular shapes ranging in size from 0. 1 to 1.5 mm affixed to a microscope slide have been measured. Formation produced by an impinging jet will be further monitored using a CCD with 1 kHz framing illuminated with pulsed light. The desired image resolution of the fuel droplets is on the 20 pm scale using early light through a highly scattering medium. A 10(exp -6)m displacement from a jet spray with a flow speed of 100 m/sec introduced by the ns grating pulse used in the imaging is negligible. Early ballistic/snake light imaging offers nondestructive and noninvasive method to observe the spatial distribution of hidden objects inside a highly scattering environment for space, biomedical, and materials applications. In this paper, the techniques we will present are time-resolved K-F transillumination imaging and time-gated scattered light imaging. With a large dynamic range and high resolution, time-gated early light imaging has the potential for improving rocket/aircraft design by determining jets shape and particle sizes. Refinements to these techniques may enable drop size measurements in the highly scattering, optically dense region of multi-element rocket injectors. These types of measurements should greatly enhance the design of stable, and higher performing rocket engines.

Galland, Pierre A.; Liang, X.; Wang, L.; Ho, P. P.; Alfano, R. R.; Breisacher, K.

1999-01-01

146

3D change detection at street level using mobile laser scanning point clouds and terrestrial images  

NASA Astrophysics Data System (ADS)

Automatic change detection and geo-database updating in the urban environment are difficult tasks. There has been much research on detecting changes with satellite and aerial images, but studies have rarely been performed at the street level, which is complex in its 3D geometry. Contemporary geo-databases include 3D street-level objects, which demand frequent data updating. Terrestrial images provides rich texture information for change detection, but the change detection with terrestrial images from different epochs sometimes faces problems with illumination changes, perspective distortions and unreliable 3D geometry caused by the lack of performance of automatic image matchers, while mobile laser scanning (MLS) data acquired from different epochs provides accurate 3D geometry for change detection, but is very expensive for periodical acquisition. This paper proposes a new method for change detection at street level by using combination of MLS point clouds and terrestrial images: the accurate but expensive MLS data acquired from an early epoch serves as the reference, and terrestrial images or photogrammetric images captured from an image-based mobile mapping system (MMS) at a later epoch are used to detect the geometrical changes between different epochs. The method will automatically mark the possible changes in each view, which provides a cost-efficient method for frequent data updating. The methodology is divided into several steps. In the first step, the point clouds are recorded by the MLS system and processed, with data cleaned and classified by semi-automatic means. In the second step, terrestrial images or mobile mapping images at a later epoch are taken and registered to the point cloud, and then point clouds are projected on each image by a weighted window based z-buffering method for view dependent 2D triangulation. In the next step, stereo pairs of the terrestrial images are rectified and re-projected between each other to check the geometrical consistency between point clouds and stereo images. Finally, an over-segmentation based graph cut optimization is carried out, taking into account the color, depth and class information to compute the changed area in the image space. The proposed method is invariant to light changes, robust to small co-registration errors between images and point clouds, and can be applied straightforwardly to 3D polyhedral models. This method can be used for 3D street data updating, city infrastructure management and damage monitoring in complex urban scenes.

Qin, Rongjun; Gruen, Armin

2014-04-01

147

Improvements in Near-Terminator and Nocturnal Cloud Masks using Satellite Imager Data over the Atmospheric Radiation Measurement Sites  

SciTech Connect

Cloud detection using satellite measurements presents a big challenge near the terminator where the visible (VIS; 0.65 {micro}m) channel becomes less reliable and the reflected solar component of the solar infrared 3.9-{micro}m channel reaches very low signal-to-noise ratio levels. As a result, clouds are underestimated near the terminator and at night over land and ocean in previous Atmospheric Radiation Measurement (ARM) Program cloud retrievals using Geostationary Operational Environmental Satellite (GOES) imager data. Cloud detection near the terminator has always been a challenge. For example, comparisons between the CLAVR-x (Clouds from Advanced Very High Resolution Radiometer [AVHRR]) cloud coverage and Geoscience Laser Altimeter System (GLAS) measurements north of 60{sup o}N indicate significant amounts of missing clouds from AVHRR because this part of the world was near the day/night terminator viewed by AVHRR. Comparisons between MODIS cloud products and GLAS at the same regions also shows the same difficulty in the MODIS cloud retrieval (Pavolonis and Heidinger 2005). Consistent detection of clouds at all times of day is needed to provide reliable cloud and radiation products for ARM and other research efforts involving the modeling of clouds and their interaction with the radiation budget. To minimize inconsistencies between daytime and nighttime retrievals, this paper develops an improved twilight and nighttime cloud mask using GOES-9, 10, and 12 imager data over the ARM sites and the continental United States (CONUS).

Trepte, Q.Z.; Minnis, P.; Heck, P.W.; Palikonda, R.

2005-03-18

148

Speckle pattern quality assessment for digital image correlation  

NASA Astrophysics Data System (ADS)

To perform digital image correlation (DIC), each image is divided into groups of pixels known as subsets or interrogation cells. Larger interrogation cells allow greater strain precision but reduce the spatial resolution of the data field. As such the spatial resolution and measurement precision of DIC are limited by the resolution of the image. In the paper the relationship between the size and density of speckles within a pattern is presented, identifying that the physical properties of a pattern have a large influence on the measurement precision which can be obtained. These physical properties are often overlooked by pattern assessment criteria which focus on the global image information content. To address this, a robust morphological methodology using edge detection is devised to evaluate the physical properties of different speckle patterns with image resolutions from 23 to 705 pixels/mm. Trends predicted from the pattern property analysis are assessed against simulated deformations identifying how small changes to the application method can result in large changes in measurement precision. An example of the methodology is included to demonstrate that the pattern properties derived from the analysis can be used to indicate pattern quality and hence minimise DIC measurement errors. Experiments are described that were conducted to validate the findings of morphological assessment and the error analysis.

Crammond, G.; Boyd, S. W.; Dulieu-Barton, J. M.

2013-12-01

149

Automatic registration of Iphone images to LASER point clouds of the urban structures using shape features  

NASA Astrophysics Data System (ADS)

Fusion of 3D airborne laser (LIDAR) data and terrestrial optical imagery can be applied in 3D urban modeling and model up-dating. The most challenging aspect of the fusion procedure is registering the terrestrial optical images on the LIDAR point clouds. In this article, we propose an approach for registering these two different data from different sensor sources. As we use iPhone camera images which are taken in front of the interested urban structure by the application user and the high resolution LIDAR point clouds of the acquired by an airborne laser sensor. After finding the photo capturing position and orientation from the iPhone photograph metafile, we automatically select the area of interest in the point cloud and transform it into a range image which has only grayscale intensity levels according to the distance from the image acquisition position. We benefit from local features for registering the iPhone image to the generated range image. In this article, we have applied the registration process based on local feature extraction and graph matching. Finally, the registration result is used for facade texture mapping on the 3D building surface mesh which is generated from the LIDAR point cloud. Our experimental results indicate possible usage of the proposed algorithm framework for 3D urban map updating and enhancing purposes.

Sirmacek, B.; Lindenbergh, R. C.; Menenti, M.

2013-10-01

150

Orientation of airborne laser scanning point clouds with multi-view, multi-scale image blocks.  

PubMed

Comprehensive 3D modeling of our environment requires integration of terrestrial and airborne data, which is collected, preferably, using laser scanning and photogrammetric methods. However, integration of these multi-source data requires accurate relative orientations. In this article, two methods for solving relative orientation problems are presented. The first method includes registration by minimizing the distances between of an airborne laser point cloud and a 3D model. The 3D model was derived from photogrammetric measurements and terrestrial laser scanning points. The first method was used as a reference and for validation. Having completed registration in the object space, the relative orientation between images and laser point cloud is known. The second method utilizes an interactive orientation method between a multi-scale image block and a laser point cloud. The multi-scale image block includes both aerial and terrestrial images. Experiments with the multi-scale image block revealed that the accuracy of a relative orientation increased when more images were included in the block. The orientations of the first and second methods were compared. The comparison showed that correct rotations were the most difficult to detect accurately by using the interactive method. Because the interactive method forces laser scanning data to fit with the images, inaccurate rotations cause corresponding shifts to image positions. However, in a test case, in which the orientation differences included only shifts, the interactive method could solve the relative orientation of an aerial image and airborne laser scanning data repeatedly within a couple of centimeters. PMID:22454569

Rönnholm, Petri; Hyyppä, Hannu; Hyyppä, Juha; Haggrén, Henrik

2009-01-01

151

Orientation of Airborne Laser Scanning Point Clouds with Multi-View, Multi-Scale Image Blocks  

PubMed Central

Comprehensive 3D modeling of our environment requires integration of terrestrial and airborne data, which is collected, preferably, using laser scanning and photogrammetric methods. However, integration of these multi-source data requires accurate relative orientations. In this article, two methods for solving relative orientation problems are presented. The first method includes registration by minimizing the distances between of an airborne laser point cloud and a 3D model. The 3D model was derived from photogrammetric measurements and terrestrial laser scanning points. The first method was used as a reference and for validation. Having completed registration in the object space, the relative orientation between images and laser point cloud is known. The second method utilizes an interactive orientation method between a multi-scale image block and a laser point cloud. The multi-scale image block includes both aerial and terrestrial images. Experiments with the multi-scale image block revealed that the accuracy of a relative orientation increased when more images were included in the block. The orientations of the first and second methods were compared. The comparison showed that correct rotations were the most difficult to detect accurately by using the interactive method. Because the interactive method forces laser scanning data to fit with the images, inaccurate rotations cause corresponding shifts to image positions. However, in a test case, in which the orientation differences included only shifts, the interactive method could solve the relative orientation of an aerial image and airborne laser scanning data repeatedly within a couple of centimeters.

Ronnholm, Petri; Hyyppa, Hannu; Hyyppa, Juha; Haggren, Henrik

2009-01-01

152

High Speed Imaging of Bubble Clouds Generated in Pulsed Ultrasound Cavitational Therapy--Histotripsy  

PubMed Central

Our recent studies have demonstrated that mechanical fractionation of tissue structure with sharply demarcated boundaries can be achieved using short (<20 ?s), high intensity ultrasound pulses delivered at low duty cycles. We have called this technique histotripsy. Histotripsy has potential clinical applications where noninvasive tissue fractionation and/or tissue removal are desired. The primary mechanism of histotripsy is thought to be acoustic cavitation, which is supported by a temporally changing acoustic backscatter observed during the histotripsy process. In this paper, a fast-gated digital camera was used to image the hypothesized cavitating bubble cloud generated by histotripsy pulses. The bubble cloud was produced at a tissue-water interface and inside an optically transparent gelatin phantom which mimics bulk tissue. The imaging shows the following: 1) Initiation of a temporally changing acoustic backscatter was due to the formation of a bubble cloud; 2) The pressure threshold to generate a bubble cloud was lower at a tissue-fluid interface than inside bulk tissue; and 3) at higher pulse pressure, the bubble cloud lasted longer and grew larger. The results add further support to the hypothesis that the histotripsy process is due to a cavitating bubble cloud and may provide insight into the sharp boundaries of histotripsy lesions.

Xu, Zhen; Raghavan, Mekhala; Hall, Timothy L.; Chang, Ching-Wei; Mycek, Mary-Ann; Fowlkes, J. Brian; Cain, Charles A.

2009-01-01

153

Spatial pattern discovery for hyperspectral images based on multiresolution analysis  

Microsoft Academic Search

A method to discover spatial patterns that are dominant or unique in each spectral band of a hyperspectral image is presented. The approach relies on the multiresolution image fusion framework as well as on exploratory visual data analysis. It is shown that the proportion of dominant details obtained from multiresolution decomposition, and their reconstructed spatial signature, provides valuable clues for

Mario Beauchemin

2012-01-01

154

Spatial pattern discovery for hyperspectral images based on multiresolution analysis  

Microsoft Academic Search

A method to discover spatial patterns that are dominant or unique in each spectral band of a hyperspectral image is presented. The approach relies on the multiresolution image fusion framework as well as on exploratory visual data analysis. It is shown that the proportion of dominant details obtained from multiresolution decomposition, and their reconstructed spatial signature, provides valuable clues for

Mario Beauchemin

2011-01-01

155

Automated estimation of mass eruption rate of volcanic eruption on satellite imagery using a cloud pattern recognition algorithm  

NASA Astrophysics Data System (ADS)

The need to detect and track the position of ash in the atmosphere has been highlighted in the past few years following the eruption Eyjafjallajokull. As a result, Volcanic Ash Advisory Centers (VAACs) are using Volcanic Ash Transport and Dispersion models (VATD) to estimate and predict the whereabouts of the ash in the atmosphere. However, these models require inputs of eruption source parameters, such as the mass eruption rate (MER), and wind fields, which are vital to properly model the ash movements. These inputs might change with time as the eruption enters different phases. This implies tracking the ash movement as conditions change, and new satellite imagery comes in. Thus, ultimately, the eruption must be detectable, regardless of changing eruption source and meteorological conditions. Volcanic cloud recognition can be particularly challenging, especially when meteorological clouds are present, which is typically the case in the tropics. Given the fact that a large fraction of the eruptions in the world happen in a tropical environment, we have based an automated volcanic cloud recognition algorithm on the fact that meteorological clouds and volcanic clouds behave differently. As a result, the pattern definition algorithm detects and defines volcanic clouds as different object types from meteorological clouds on satellite imagery. Following detection and definition, the algorithm then estimates the area covered by the ash. The area is then analyzed with respect to a plume growth rate methodology to get estimation of the volumetric and mass growth with time. This way, we were able to get an estimation of the MER with time, as plume growth is dependent on MER. To test our approach, we used the examples of two eruptions of different source strength, in two different climatic regimes, and for which therefore the weather during the eruption was quite different: Manam (Papua New Guinea) January 27 2005, which produced a stratospheric umbrella cloud and was difficult to distinguish from meteorological clouds, and Okmok (Alaska) July 12 2008, which was also an umbrella cloud, but started as an ash-rich cloud before getting a vapor rich pulse into the cloud. The new methods may in the future allow for fast, easy and automated detection of volcanic clouds as well as remote assessment of the MER with time, even for inaccessible volcanoes. The methods may thus provide an additional path to estimation of the ESP and the forecasting of ash cloud propagation with time as the eruption changes.

Pouget, Solene; Jansons, Emile; Bursik, Marcus; Tupper, Andrew; Patra, Abani; Pitman, Bruce; Carn, Simon

2014-05-01

156

Coordinated 1996 HST and IRTF Imaging of Neptune and Triton. III. Neptune's Atmospheric Circulation and Cloud Structure  

NASA Astrophysics Data System (ADS)

The first coordinated multispectral imaging of Neptune and Triton, using both the Hubble Space Telescope and the NASA Infrared Telescope Facility in August 1996 (L. A. Sromovsky et al., 149, 416-434, 435-458), provides new insights into Neptune's atmospheric circulation and cloud structure. From our 1996 data we derived cloud-tracked winds for 18 features spanning latitudes from 61°S to 38°N, finding generally close agreement with the smoothed 1989 Voyager wind profile (Sromovsky et al. 1993, Icarus105, 110-141), except for features associated with a northern Great Dark Spot (GDS), which moved with the spot rather than with the local mass flow, providing another example of GDS traveling companions. In addition to finding a GDS at ˜32°N, thought to be the same one first seen in 1994 near the same latitude (Hammel et al. 1995, Science268, 1740-1742), we also found a new kind of GDS at ˜15°N, which is unusual because of its low latitude and lack of a bright companion. From blue images we determined that the dark cloud band near 60°S latitude is significantly nonaxisymmetric, as was a similar band in 1989 Voyager images, both with a wavenumber-one zonal structure and a ˜5° latitudinal variation. We also identified a persistent pattern of clouds at 45°S, which exhibit strong variations in brightness on yearly time scales. Using HST archived observations, we determined cloud-tracked winds for June and November 1994 and September 1995, confirming and extending the 1995 result of Hammel and Lockwood (1997, Icarus129, 466-481) that most winds agreed with the Voyager profile. A significant exception we found in November 1994 is the ˜100 m/s meridional motion within the transient structure identified as the "bright complex" by H. B. Hammel and G. W. Lockwood (1997, Icarus129, 466-481). The integrated brightness of this group of GDS traveling companions is sufficient to produce a hemispheric brightness asymmetry of 0.36 mag (Sromovsky et al., 149, 435-458), comparable to the 0.44 mag associated with the 1987 "outburst" maximum (Hammel et al. 1992, Icarus99, 363-367). We determined spectral differences in cloud bands using complete global mosaics of 1996 imagery. Colocation of features in HST and groundbased near-IR images enabled us to characterize spectral variations in discrete features from the visible to 2.4 ?m, from which we estimated cloud heights for discrete bright features ranging from 60 to 230 mbars. We found the equatorial atmosphere that is free of bright clouds to be very dark beyond 0.7 ?m, from which we derived new upper bounds of ˜0.2 and ˜0.1 at 1.27 and 1.6 ?m, respectively, on the single-scattering albedo of the putative 3.8-bar H 2S cloud.

Sromovsky, L. A.; Fry, P. M.; Dowling, T. E.; Baines, K. H.; Limaye, S. S.

2001-02-01

157

Characterization of aerosol-containing chemical simulant clouds using a sensitive, thermal infrared imaging spectrometer  

NASA Astrophysics Data System (ADS)

A sensitive, ground-based thermal imaging spectrometer was deployed at the Army's Dugway Proving Ground to remotely monitor explosively released chemical-warfare-agent-simulant clouds from stand-off ranges of a few kilometers. The sensor has 128 spectral bands covering the 7.6 to 13.5 micron region. The measured cloud spectra clearly showed scattering of high-elevation-angle sky radiance by liquid aerosols or dust in the clouds: we present arguments that show why the scattering is most likely due to dust. This observation has significant implications for early detection of dust-laden chemical clouds. On one hand, detection algorithms must properly account for the scattered radiation component, which would include out-of-scene radiation components as well as a dust signature; on the other hand, this scattering gives rise to an enhanced "delta-T" for detection by a ground-based sensor.

Hall, Jeffrey L.; D'Amico, Francis M.; Kolodzey, Steven J.; Qian, Jun; Polak, Mark L.; Westerberg, Karl; Chang, Clement S.

2011-05-01

158

The effects of orography on cloud and rainfall patterns during typhoon Ketsana (2009)  

NASA Astrophysics Data System (ADS)

The objective of this study is to investigate the effects of orography on the rainfall, wind, and cloud systems of the TCs in Malaysia and Indochina. To determine the relationship of the typhoon with the orographic effect, remote sensing techniques such as the Global Digital Elevation Model (GDEM) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite, rainfall data from the Fengyun 2D (FY-2D), and radiosonde data were applied in this study. From this study, the following conclusions can be drawn: 1) rainfall tends to be distributed over high mountain regions; 2) wind flow will change its direction upon encountering any restrictions, especially those of high terrain regions; and 3) cloud patterns are deformed by high mountains and tend to flow with the mountains' structure because of the orographic effects. The regions most affected by Typhoon Ketsana in the study area were Vietnam in Indochina, Sabah in East Malaysia (EM), Kelantan and Terengganu in Peninsular Malaysia (PM). From the comparison among the study areas, it was found that Indochina had the most significant results for the orographic effects on typhoon activity, followed by the tail effects in EM. This phenomenon was found in PM, although it was not as significant as the other study areas. This remote sensing technique allows tropical cyclones to be forecasted and their impacts to be defined, and it allows disaster zones to be determined.

Fuyi, Tan; MatJafri, Mohd Zubir; Lim, Hwee-San; Abdullah, Khiruddin

2012-10-01

159

Branching patterns of the male internal iliac artery: imaging findings  

Microsoft Academic Search

The aim of this study was to establish the imaging findings of the main branching patterns of the male internal iliac arteries,\\u000a using different imaging modalities (angio MR, angio CT and digital angiography). Twenty-one males (mean age 73.2 years) underwent\\u000a imaging evaluation with angio MR, angio CT and digital angiography to define the internal iliac artery anatomy before selective\\u000a embolization of

Tiago Bilhim; Diogo Casal; Andrea Furtado; Diogo Pais; João Erse Goyri O’Neill; João Martins Pisco

2011-01-01

160

The smoothing of electronic speckle pattern interferometric images  

NASA Astrophysics Data System (ADS)

A simple method of smoothing electronic speckle pattern interferometric images is demonstrated. A new image is created from the original by assuming that the speckles can be modeled as multiplicative noise, and replacing each pixel by the variance of gray level intensities taken over a rectangular window. Results from several window sizes are presented. The amount of smoothing is estimated by inspection of the amount of noise left following the application of a fringe minima detection algorithm to the smoothed image.

Crennell, K. M.; Bowler, I. W.

161

Effects of baroclinicity on the cloud pattern and structure of polar lows: A high-resolution numerical experiment  

NASA Astrophysics Data System (ADS)

High-resolution numerical experiments using a three-dimensional non-hydrostatic model with horizontal grid size of 5 or 2 km are performed to clarify what determines the structure and cloud pattern of polar lows. An axisymmetric initial vortex is imposed in a baroclinic basic state for which thermal wind balance holds. It is found that when the baroclinicity is absent, a hurricane-like vortex with spiral cloud bands, a cloud-free eye, and a warm core develops. When the baroclinicity is strong, on the other hand, a vortex with a comma-shaped cloud and slightly larger horizontal scale develops. The former appears to develop due to CISK/WISHE mechanism, while the latter due to baroclinic instability modified by latent heating.

Yanase, W.; Niino, H.

2005-01-01

162

Machine learning patterns for neuroimaging-genetic studies in the cloud.  

PubMed

Brain imaging is a natural intermediate phenotype to understand the link between genetic information and behavior or brain pathologies risk factors. Massive efforts have been made in the last few years to acquire high-dimensional neuroimaging and genetic data on large cohorts of subjects. The statistical analysis of such data is carried out with increasingly sophisticated techniques and represents a great computational challenge. Fortunately, increasing computational power in distributed architectures can be harnessed, if new neuroinformatics infrastructures are designed and training to use these new tools is provided. Combining a MapReduce framework (TomusBLOB) with machine learning algorithms (Scikit-learn library), we design a scalable analysis tool that can deal with non-parametric statistics on high-dimensional data. End-users describe the statistical procedure to perform and can then test the model on their own computers before running the very same code in the cloud at a larger scale. We illustrate the potential of our approach on real data with an experiment showing how the functional signal in subcortical brain regions can be significantly fit with genome-wide genotypes. This experiment demonstrates the scalability and the reliability of our framework in the cloud with a 2 weeks deployment on hundreds of virtual machines. PMID:24782753

Da Mota, Benoit; Tudoran, Radu; Costan, Alexandru; Varoquaux, Gaël; Brasche, Goetz; Conrod, Patricia; Lemaitre, Herve; Paus, Tomas; Rietschel, Marcella; Frouin, Vincent; Poline, Jean-Baptiste; Antoniu, Gabriel; Thirion, Bertrand

2014-01-01

163

Machine learning patterns for neuroimaging-genetic studies in the cloud  

PubMed Central

Brain imaging is a natural intermediate phenotype to understand the link between genetic information and behavior or brain pathologies risk factors. Massive efforts have been made in the last few years to acquire high-dimensional neuroimaging and genetic data on large cohorts of subjects. The statistical analysis of such data is carried out with increasingly sophisticated techniques and represents a great computational challenge. Fortunately, increasing computational power in distributed architectures can be harnessed, if new neuroinformatics infrastructures are designed and training to use these new tools is provided. Combining a MapReduce framework (TomusBLOB) with machine learning algorithms (Scikit-learn library), we design a scalable analysis tool that can deal with non-parametric statistics on high-dimensional data. End-users describe the statistical procedure to perform and can then test the model on their own computers before running the very same code in the cloud at a larger scale. We illustrate the potential of our approach on real data with an experiment showing how the functional signal in subcortical brain regions can be significantly fit with genome-wide genotypes. This experiment demonstrates the scalability and the reliability of our framework in the cloud with a 2 weeks deployment on hundreds of virtual machines.

Da Mota, Benoit; Tudoran, Radu; Costan, Alexandru; Varoquaux, Gael; Brasche, Goetz; Conrod, Patricia; Lemaitre, Herve; Paus, Tomas; Rietschel, Marcella; Frouin, Vincent; Poline, Jean-Baptiste; Antoniu, Gabriel; Thirion, Bertrand

2014-01-01

164

Direct imaging of a massive dust cloud around R Coronae Borealis  

NASA Astrophysics Data System (ADS)

We present recent polarimetric images of the highly variable star R CrB using ExPo and archival WFPC2 images from the HST. We observed R CrB during its current dramatic minimum where it decreased more than 9 mag due to the formation of an obscuring dust cloud. Since the dust cloud is only in the line-of-sight, it mimics a coronograph allowing the imaging of the star's circumstellar environment. Our polarimetric observations surprisingly show another scattering dust cloud at approximately 1.3'' or 2000 AU from the star. We find that to obtain a decrease in the stellar light of 9 mag and with 30% of the light being reemitted at infrared wavelengths (from R CrB's SED) the grains in R CrB's circumstellar environment must have a very low albedo of approximately 0.07%. We show that the properties of the dust clouds formed around R CrB are best fitted using a combination of two distinct populations of grains size. The first are the extremely small 5 nm grains, formed in the low density continuous wind, and the second population of large grains (~0.14 ?m) which are found in the ejected dust clouds. The observed scattering cloud, not only contains such large grains, but is exceptionally massive compared to the average cloud. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

Jeffers, S. V.; Min, M.; Waters, L. B. F. M.; Canovas, H.; Rodenhuis, M.; de Juan Ovelar, M.; Chies-Santos, A. L.; Keller, C. U.

2012-03-01

165

Tag, cloud and ontology based retrieval of images  

Microsoft Academic Search

In this paper, we describe the results of an experiment designed to compare different user interfaces for retrieving tagged images from a database comprised of images of Jewish cultural heritage. The participants were given ten scenarios, for which they were asked to retrieve all the relevant images in the database. Each participant was randomly assigned to one of four retrieval

Judit Bar-Ilan; Maayan Zhitomirsky-Geffet; Yitzchak Miller; Snunith Shoham

2010-01-01

166

Physics principles in radiometric infrared imaging of clouds in the atmosphere  

NASA Astrophysics Data System (ADS)

Imaging the atmosphere with a thermal infrared camera can yield a rich variety of information, ranging from the water-vapour content to the spatial distribution of clouds. Such remote sensing measurements are being used to study climate and to characterize ground-station sites for Earth-space optical communications. The key to turning interesting but qualitative images into the highly accurate quantitative images required for this type of research is careful radiometric calibration. This is especially true when using uncooled microbolometer cameras, which are becoming widely available at relatively low cost. When such cameras are calibrated properly, their images illustrate a variety of important basic principles of optics and atmospheric physics related to thermal emission and absorption by atmospheric gases and clouds.

Shaw, Joseph A.; Nugent, Paul W.

2013-11-01

167

The Investigation of Cloud-Computing-based Image Mining Mechanism in Mobile Communication WEB on Android  

Microsoft Academic Search

With the development of 3G network technology, the rapid upgrading of mobile phone hardware, and the refined requirements for mobile phones by mobile phone users, it is essential for mobile phones to be able to promptly and accurately process images. A mobile phone terminal sends the service requests to cloud computer system which then processes the requests and sends the

Cai-Dong Gu; Kan Lu; Jian-Ping Wu; Ying-li Fu; Jing-xiang Li; Chang-shui Xiao; Mao-xin Si; Zhao-bin Liu

2010-01-01

168

An approach to stereo-point cloud registration using image homographies  

NASA Astrophysics Data System (ADS)

A mobile robot equipped with a stereo camera can measure both the video image of a scene and the visual disparity in the scene. The disparity image can be used to generate a collection of points, each representing the location of a surface in the visual scene as a 3D point with respect to the location of the stereo camera: a point cloud. If the stereo camera is moving, e.g., mounted on a moving robot, aligning these scans becomes a difficult, and computationally expensive problem. Many finely tuned versions of the iterative closest point algorithm (ICP) have been used throughout robotics for registration of these sets of scans. However, ICP relies on theoretical convergence to the nearest local minimum of the dynamical system: there is no guarantee that ICP will accurately align the scans. In order to address two problems with ICP, convergence time and accuracy of convergence, we have developed an improvement by using salient keypoints from successive video images to calculate an affine transformation estimate of the camera location. This transformation, when applied to the target point cloud, provides ICP an initial guess to reduce the computational time required for point cloud registration and improve the quality of registration. We report ICP convergence times with and without image information for a set of stereo data point clouds to demonstrate the effectiveness of the approach.

Fox, Stephen D.; Lyons, Damian M.

2012-01-01

169

Fluorescence Imaging for Visualization of the Ion Cloud in a Quadrupole Ion Trap Mass Spectrometer  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence is used to visualize populations of gaseous ions stored in a quadrupole ion trap (QIT) mass spectrometer. Presented images include the first fluorescence image of molecular ions collected under conditions typically used in mass spectrometry experiments. Under these "normal" mass spectrometry conditions, the radial ( r) and axial ( z) full-width at half maxima (FWHM) of the detected ion cloud are 615 and 214 ?m, respectively, corresponding to ~6 % of r 0 and ~3 % of z 0 for the QIT used. The effects on the shape and size of the ion cloud caused by varying the pressure of helium bath gas, the number of trapped ions, and the Mathieu parameter q z are visualized and discussed. When a "tickle voltage" is applied to the exit end-cap electrode, as is done in collisionally activated dissociation, a significant elongation in the axial, but not the radial, dimension of the ion cloud is apparent. Finally, using spectroscopically distinguishable fluorophores of two different m/ z values, images are presented that illustrate stratification of the ion cloud; ions of lower m/ z (higher q z ) are located in the center of the trapping region, effectively excluding higher m/ z (lower q z ) ions, which form a surrounding layer. Fluorescence images such as those presented here provide a useful reference for better understanding the collective behavior of ions in radio frequency (rf) trapping devices and how phenomena such as collisions and space-charge affect ion distribution.

Talbot, Francis O.; Sciuto, Stephen V.; Jockusch, Rebecca A.

2013-12-01

170

Optical Processing of Speckle Images with Bacteriorhodopsin for Pattern Recognition  

NASA Technical Reports Server (NTRS)

Logarithmic processing of images with multiplicative noise characteristics can be utilized to transform the image into one with an additive noise distribution. This simplifies subsequent image processing steps for applications such as image restoration or correlation for pattern recognition. One particularly common form of multiplicative noise is speckle, for which the logarithmic operation not only produces additive noise, but also makes it of constant variance (signal-independent). We examine the optical transmission properties of some bacteriorhodopsin films here and find them well suited to implement such a pointwise logarithmic transformation optically in a parallel fashion. We present experimental results of the optical conversion of speckle images into transformed images with additive, signal-independent noise statistics using the real-time photochromic properties of bacteriorhodopsin. We provide an example of improved correlation performance in terms of correlation peak signal-to-noise for such a transformed speckle image.

Downie, John D.; Tucker, Deanne (Technical Monitor)

1994-01-01

171

Pattern based 3D image Steganography  

NASA Astrophysics Data System (ADS)

This paper proposes a new high capacity Steganographic scheme using 3D geometric models. The novel algorithm re-triangulates a part of a triangle mesh and embeds the secret information into newly added position of triangle meshes. Up to nine bits of secret data can be embedded into vertices of a triangle without causing any changes in the visual quality and the geometric properties of the cover image. Experimental results show that the proposed algorithm is secure, with high capacity and low distortion rate. Our algorithm also resists against uniform affine transformations such as cropping, rotation and scaling. Also, the performance of the method is compared with other existing 3D Steganography algorithms. [Figure not available: see fulltext.

Thiyagarajan, P.; Natarajan, V.; Aghila, G.; Prasanna Venkatesan, V.; Anitha, R.

2013-03-01

172

Effects of stitching pattern on diffractive telescope image quality  

NASA Astrophysics Data System (ADS)

Diffraction image technology is an updated technology. It has more potential for developing the larger aperture and lightweight telescope than the conventional refractive and reflective optics. In order to develop a large aperture diffractive telescope, the key is to solve the problem of large aperture lens stitching. Different stitching patterns have different effects on the image quality. However, the stitching pattern for diffractive telescope is different from the conventional refractive and reflective telescope. This paper, for the first time, studies the theory of stitching pattern for diffractive telescope. On the basis of theoretical analysis, a long-wavelength infrared diffractive telescope of segmented-lens is designed and for the first time, good results through stitching experiments have been achieved. According to theoretical analysis and experiment verification, the paper gives the best stitching pattern on diffractive telescope.

Zhang, ZhouFeng; Xie, YongJun; Kang, FuZeng; Wang, YanJun

2014-02-01

173

Reconstruction of typhoon path and cloud image from descriptors  

Microsoft Academic Search

In this paper, we propose a novel method to reconstruct the path and contour of a typhoon in a satellite image using mathematical morphology and descriptors. Generally, it is hard to depict the contour and path of a typhoon by a simple way in the satellite images. Especially, if we would like to track changes of a typhoon in the

Jun-heng Yeh; Tsang-long Pao; Chung-lang Lee; Wei-ta Lai

2007-01-01

174

Biometric Authentication Using Infrared Imaging of Hand Vein Patterns  

Microsoft Academic Search

\\u000a Hand vein patterns are unique and universal. Vein pattern is used as biometric feature in recent years. But, it is not very\\u000a much popular biometric system as compared to other systems like fingerprint, iris etc, because of the higher cost. For conventional\\u000a algorithm, it is necessary to use high quality images, which demand high-priced collection devices. There are two approaches

Debnath Bhattacharyya; A. Shrotri; S. C. Rethrekar; M. H. Patil; Farkhod A. Alisherov; Tai-Hoon Kim

2010-01-01

175

Automatic Pattern Extraction and Classification for Chromosome Images  

NASA Astrophysics Data System (ADS)

Chromosome image analysis and pattern classification is one of the essential tasks in genetic syndrome diagnoses. An automatic procedure is introduced for chromosome image analysis. The pale-path algorithm is proposed to segment touching and overlapping chromosomes. Medial axis is extracted by the middle point algorithm. Chromosome band is enhanced by the algorithm based on multiscale wavelets Bi-spline, and extracted by average gray profile, gradient profile and shape profile. The multilayer classifier is used to classify the chromosome pattern calculated by weighted density distribution algorithm. Experiment results demonstrate that the algorithms perform well.

Ming, Delie; Tian, Jinwen

2010-07-01

176

Hex-square moire patterns in imagers using microchannel plates  

NASA Technical Reports Server (NTRS)

In electronic imaging detectors using microchannel plates, the mismatch between the pixels on a square mesh and the microchannels on a hexagonal mesh produces moire image defects. Theoretical statistical estimates of the sizes of the microposition offsets and the flat field intensity errors are calculated, showing the trade-off between resolution and position accuracy. A distinction is made between moments of spot images and moments of the single-pixel-response functions. As the resolution between the hex and square meshes is improved, the detector resolution is improved, but at the expense of an about 10 percent moire pattern. These moire patterns will not be properly corrected by dividing by the flat field image.

Lawrence, George M.

1989-01-01

177

Analysis of Karman vortex clouds revealed by satellite images  

NASA Astrophysics Data System (ADS)

The analysis of the Karman vortex cloud street in the wake of Cheju Island Korea in geostationary meteorological satellite imageries together with meteorological data indicate following features. (1) The frequency of formation depends upon that of a cold-air outbreak. Frequency of a well developed one during a cold season of Dec., Jan., Feb. and March is in average 10. (2) Favorable meteorological conditions for the formation is a sharp air temperature inversion below the top of the highest mountain in the center of the island and a steady cold northerly wind. (3) Displacement speed of the vortices has an inverse relationship with the size of b/a where a is the distance of successive vortex pair and b is the distance between the vortices consisting a pair. (4) The time required to reach mature stage of a vortex pair is around three hours.

Tsuchiya, K.; Tokuno, M.

178

Effects of clouds on the Earth radiation budget; Seasonal and inter-annual patterns  

NASA Technical Reports Server (NTRS)

Seasonal and regional variations of clouds and their effects on the climatological parameters were studied. The climatological parameters surface temperature, solar insulation, short-wave absorbed, long wave emitted, and net radiation were considered. The data of climatological parameters consisted of about 20 parameters of Earth radiation budget and clouds of 2070 target areas which covered the globe. It consisted of daily and monthly averages of each parameter for each target area for the period, Jun. 1979 - May 1980. Cloud forcing and black body temperature at the top of the atmosphere were calculated. Interactions of clouds, cloud forcing, black body temperature, and the climatological parameters were investigated and analyzed.

Dhuria, Harbans L.

1992-01-01

179

Analysis of Breathing Air Flow Patterns in Thermal Imaging  

Microsoft Academic Search

We introduce a novel methodology to characterize breathing patterns based on thermal infrared imaging. We have retrofitted a Mid-Wave Infra-Red (MWIR) imaging system with a narrow band-pass filter in the CO2 absorption band (4130 - 4427 nm). We use this system to record the radiation information from within the breathing flow region. Based on this information we compute the mean

Jin Fei; Ioannis Pavlidis

2006-01-01

180

Virtual dark-field images reconstructed from electron diffraction patterns  

NASA Astrophysics Data System (ADS)

Bright- and dark-field images are reconstructed by extracting the intensities of selected spots from a succession of digitalized electron diffraction patterns collected using a transmission electron microscope by scanning the focused beam over the area of interest. The procedure is similar to the generation of the scanning-transmission electron microscopy images. Several examples are shown to illustrate the flexibility and potentiality of such numerical off-line reconstruction.

Rauch, Edgar F.; Véron, Muriel

2014-04-01

181

Image analysis of dye stained patterns in soils  

NASA Astrophysics Data System (ADS)

Quality of surface water and groundwater is directly affected by flow processes in the unsaturated zone. In general, it is difficult to measure or model water flow. Indeed, parametrization of hydrological models is problematic and often no unique solution exists. To visualise flow patterns in soils directly dye tracer studies can be done. These experiments provide images of stained soil profiles and their evaluation demands knowledge in hydrology as well as in image analysis and statistics. First, these photographs are converted to binary images classifying the pixels in dye stained and non-stained ones. Then, some feature extraction is necessary to discern relevant hydrological information. In our study we propose to use several index functions to extract different (ideally complementary) features. We associate each image row with a feature vector (i.e. a certain number of image function values) and use these features to cluster the image rows to identify similar image areas. Because images of stained profiles might have different reasonable clusterings, we calculate multiple consensus clusterings. An expert can explore these different solutions and base his/her interpretation of predominant flow mechanisms on quantitative (objective) criteria. The complete workflow from reading-in binary images to final clusterings has been implemented in the free R system, a language and environment for statistical computing. The calculation of image indices is part of our own package Indigo, manipulation of binary images, clustering and visualization of results are done using either build-in facilities in R, additional R packages or the LATEX system.

Bogner, Christina; Trancón y Widemann, Baltasar; Lange, Holger

2013-04-01

182

Application of CloudSat cloud classification maps and MODIS multi-spectral satellite imagery in identifying false rain from satellite images  

NASA Astrophysics Data System (ADS)

In recent years, the emergence of various satellite-based precipitation products with high spatial resolutions and global coverage has resulted in new sources of uninterrupted precipitation estimates. However, due to lack of information on the associated uncertainties and reliability of these products, they are not well integrated into operational and decision making applications. Comparing in-situ rain measurements with satellite precipitation data reveals considerable false alarm in satellite precipitation measurements in the presence of high cold clouds. In this study, application of multi-spectral satellite imagery from MODIS and CloudSat cloud classification maps is investigated to identify false rain detection in satellite precipitation products (e.g., PERSIANN). Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA Earth Observing System Aqua and Terra platform with 36 spectral bands provides valuable information about cloud microphysical characteristics. Additionally, CloudSat, a NASA Earth Sciences Systems Pathfinder (ESSP) mission, is designed to measure vertical structure of clouds from space. The CloudSat radar flies in formation with Aqua with only an average of about 60 s delay. The availability of cloud classes based on CloudSat CLDCLASS product together with multi-spectral capabilities of MODIS makes it possible to create a training data set to distinguish different types of clouds based on their radiances. The training data set is employed to identify high non-precipitating clouds such as cirrus and alto-stratus and remove false precipitation signals in PERSIANN satellite precipitation product. Based on the training data (July 10, 2008 until Sept 10, 2008) more than 12000 single layer cloudy pixels with their spectral characteristics are investigated. In this data set the brightness temperature difference of 8.5 and 11 micrometer channels (BTD[8.5-11]) for cirrus and altos-stratus clouds are more than 2K and 1K respectively. Both of these types of clouds are non-precipitating high that are often miss identified as light rain in the PERSIANN infrared based precipitation algorithm. Finding all pixels with BTD[8.5-11] greater than 1K, the non-precipitating high clouds can be identifies and the estimated precipitation can be removed from the precipitation algorithm. The results suggest a significant improvement in detecting non-precipitating clouds and reducing false precipitation in comparison with radar-based gauge adjusted data over the United States.

Nasrollahi, N.; Hsu, K.; Sorooshian, S.

2011-12-01

183

High-resolution imaging of the galactic cloud Monoceros R2  

NASA Technical Reports Server (NTRS)

We present high-resolution images (9.8 arcsec x 8.5 arcsec beam size) of HCO(+) J = 1-0 emission from the Galactic cloud Mon R2 obtained using the Hat Creek millimeter interferometer and the Five College Radio Astronomy Observatory 14 m antenna. The HCO(+) emission comes from small optically thick clumps as well as from an extended component. We discuss the relationship between the H II region, as traced by the continuum emission, molecular outflows, as traced by CO emission, and the dense molecular cloud, as traced by the HCO(+) emission. The abundance of HCO(+) in the most massive part of the cloud is consistent with values derived from recent molecular line surveys, but it is relatively enhanced in the less massive regions.

Gonatas, Constantine P.; Palmer, Patrick; Novak, G.

1992-01-01

184

Hiding a checkered-pattern carrier-screen image in a camouflaged halftone image  

NASA Astrophysics Data System (ADS)

As carrier-screen images, we have developed checkered-pattern carrier-screen images, which can be physically decoded by superimposing a checkered pattern. We also proposed a decoding method by image sampling with an ordinary compact digital camera. To obtain a better decoding result, each carrier-screen image should be output at a low resolution. However, secret information can be detected when you observe the image carefully. Thus, a hiding process is an important technique. In this paper, we propose an advanced hiding method by embedding the carrier-screen image into another significant image to generate a camouflaged halftone image. The proposed embedding method can be performed through a simple sequential process of blending and halftoning.

Shogenji, Rui; Ohtsubo, Junji

2014-05-01

185

Low Clouds and Fog Characterization over Iberian Peninsula using Meteosat Second Generation Images  

NASA Astrophysics Data System (ADS)

Fog is defined as a collection of suspended water droplets or ice crystals in the air near the Earth's surface that lead to a reduction of horizontal visibility below 1 km (National Oceanic and Atmospheric Administration, 1995). Fog is a stratiform cloud with similar radiative characteristics, for this reason the difference between fog and low stratus clouds is of little importance for remote sensing applications. Fog and low clouds are important atmospheric phenomena, mainly because of their impact on traffic safety and air quality, acting as an obstruction to traffic at land, sea and in the air. The purpose of this work is to develop the method of fog/low clouds detection and analysis on nighttime using Meteosat Second Generation data. This study is focused on the characterization of these atmospheric phenomena in different study cases over the Iberian Peninsula with distinct orography. Firstly, fog/low clouds detection is implemented as a composition of three infrared channels 12.0, 10.8 and 3.9 µm from SEVIRI radiometer on board European geostationary satellite Meteosat (Meteosat-9). The algorithm of detection makes use of a combination of these channels and their differences by creating RGB composites images. On this way, it displays the spatial coverage and location of fog entities. Secondly, this technique allows separating pixels which are indicated as fog/low clouds from clear pixels, assessing the properties of individual pixels using appropriated thresholds of brightness temperature. Thus, it achieves a full analysis of the extent and distribution of fog and its evolution over time. The results of this study have been checked by using ground-based point measurements available as METAR data. Despite the flaws in this sort of inter-comparison approach, the outcome produces to accurate fog/low clouds detection. This work encompasses the way to obtain spatial information from this atmospheric phenomenon by means of satellite imagery.

Sánchez, Beatriz; Maqueda, Gregorio

2014-05-01

186

HARP-B and Wide-Field Imaging of Molecular Clouds  

NASA Astrophysics Data System (ADS)

Molecular clouds within our galaxy provide excellent opportunities to study the processes of star formation in detail. They extend over large regions of the sky, and therefore wide-field imaging is required to capture all of the structure inside them, and to investigate their varied conditions. Performing this task efficiently, in high resolution, and over statistically useful numbers of clouds can best be achieved using array receivers. However these are a relatively new development due to the difficulty of constructing instrumentation for the millimetre and sub-millimetre wavelengths at which molecular clouds emit. Part I of this thesis describes HARP-B - a new heterodyne array receiver operating at 345GHz on the James Clerk Maxwell Telescope. The work described focusses on the optics, interferometer and commissioning of HARP-B. Careful testing and alignment of the optics was necessary to ensure that HARP-B would perform as required. Its Mach-Zehnder interferometer was put under computer control and characterised to allow it to be used as an effective sideband filter. This part concludes with the integration and commissioning of the receiver, leading up to first light. Part II then presents wide-field observations of the IC5146 and L977 molecular clouds, made with HARP-B and other instruments at the JCMT and IRAM 30m telescopes. For IC5146, SCUBA continuum images and a dust extinction map were already available. These were complemented by spectral observations of C18O 1-0, C18O 2-1 and the 3-2 transition of 12CO, 13CO and C18O. The data were used to study the cloud structure, excitation conditions and dust properties. SCUBA continuum and C18O 2-1 observations were made of L977 and analysed along with the existing dust extinction map in order to study the dust and gas properties, and the structure of the molecular cloud.

Bell, Graham S.

2008-10-01

187

Ice cloud properties in ice-over-water cloud systems using Tropical Rainfall Measuring Mission (TRMM) visible and infrared scanner and TRMM Microwave Imager data  

NASA Astrophysics Data System (ADS)

A multilayered cloud retrieval system (MCRS) is updated and used to estimate ice water path in maritime ice-over-water clouds using Visible and Infrared Scanner (VIRS) and Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) measurements acquired over the Tropics between January and August 1998. Lookup tables of top-of-atmosphere 0.65-?m reflectance are developed for ice-over-water cloud systems using radiative transfer calculations for various combinations of ice-over-water cloud layers. The liquid and ice water paths, LWP and IWP, respectively, are determined with the MCRS using these lookup tables with a combination of microwave (MW), visible (VIS), and infrared (IR) data. LWP, determined directly from the TMI MW data, is used to define the lower-level cloud properties to select the proper lookup table. The properties of the upper-level ice clouds, such as optical depth and effective size, are then derived using the Visible-Infrared Solar-infrared Split-Window technique (VISST), which matches the VIRS IR, 3.9 ?m, and VIS data to the multilayer cloud lookup table reflectances and a set of emittance parameterizations. Initial comparisons with surface-based radar retrievals suggest that this enhanced MCRS can significantly improve the accuracy and decrease the IWP in overlapped clouds by 42 and 13% compared to using the single-layer VISST and an earlier simplified MW-VIS-IR (MVI) differencing method, respectively, for ice-over-water cloud systems. The tropical distribution of ice-over-water clouds is the same as derived earlier from combined TMI and VIRS data, but the new values of IWP and optical depth are slightly larger than the older MVI values and exceed those of single-layered clouds by 7 and 11%, respectively. The mean IWP from the MCRS is 8-14% greater than that retrieved from radar retrievals of overlapped clouds over two surface sites, and the standard deviations of the differences are similar to those for single-layered clouds. Examples of a method for applying the MCRS over land without MW data yield similar differences with the surface retrievals. By combining the MCRS with other techniques that focus primarily on optically thin cirrus over low water clouds, it will be possible to more fully assess the IWP in all conditions over ocean except for precipitating systems.

Minnis, Patrick; Huang, Jianping; Lin, Bing; Yi, Yuhong; Arduini, Robert F.; Fan, Tai-Fang; Ayers, J. Kirk; Mace, Gerald G.

2007-03-01

188

Diurnal cloud-to-ground lightning patterns in Arizona during the southwest monsoon  

SciTech Connect

Cloud-to-ground (CG) lightning shows great variability across Arizona from one year to the next as well as from one day to the next. Availability of moisture, location of the subtropical ridge axis, transitory troughs in both the westerlies and easterlies, and low-level moisture surges from the Gulf of California can affect thunderstorm occurrence, which, in turn, will affect lightning production. Diurnal CG lightning patterns in Arizona are also determined by daily heating cycles and topography. Six years of Bureau of Land Management CG flash data are used in this investigation. In Arizona, lightning usually starts first, on a daily basis, in the plateau region and extends in an arc from the White Mountains of eastern Arizona westward across the Mogollon Rim and then northward onto the Kaibab Plateau of northern Arizona. Flash activity moves in a more or less continuous fashion off the plateau, south and westward down the topography gradient, and enters the lower desert by early evening. At the same time, flash activity develops in the highlands of southeast Arizona and moves west-northwestward, reaching the lower desert by late afternoon. Precipitation and lightning are well correlated, except that precipitation seems to linger longer than lightning, probably due to the occasional development of mesoscale convective systems, which produce light stratiform precipitation during their dissipation stage.

Watson, A.I.; Lopez, R.E.; Holle, R.L. [NOAA, Norman, OK (United States)] [NOAA, Norman, OK (United States)

1994-08-01

189

An Approach to Finding and Refinement Planes in 3D Points Cloud, Obtained Under 3D Recovery from Image Set  

Microsoft Academic Search

An algorithm of structure analysis of an input 3D points cloud and planes discrimination is proposed. The algorithm is based on the hierarchical and randomized Hough transform. The algorithm al- lows detecting image regions corresponding to planes instead of separate points, and partially converting 3D model from cloud of points to refined mesh.

Ekaterina V. Semeikina; Dmitry V. Yurin

190

Automatic registration of terrestrial point clouds based on panoramic reflectance images and efficient BaySAC  

NASA Astrophysics Data System (ADS)

This paper presents a new approach to automatic registration of terrestrial laser scanning (TLS) point clouds utilizing a novel robust estimation method by an efficient BaySAC (BAYes SAmpling Consensus). The proposed method directly generates reflectance images from 3D point clouds, and then using SIFT algorithm extracts keypoints to identify corresponding image points. The 3D corresponding points, from which transformation parameters between point clouds are computed, are acquired by mapping the 2D ones onto the point cloud. To remove false accepted correspondences, we implement a conditional sampling method to select the n data points with the highest inlier probabilities as a hypothesis set and update the inlier probabilities of each data point using simplified Bayes' rule for the purpose of improving the computation efficiency. The prior probability is estimated by the verification of the distance invariance between correspondences. The proposed approach is tested on four data sets acquired by three different scanners. The results show that, comparing with the performance of RANSAC, BaySAC leads to less iterations and cheaper computation cost when the hypothesis set is contaminated with more outliers. The registration results also indicate that, the proposed algorithm can achieve high registration accuracy on all experimental datasets.

Kang, Zhizhong

2013-10-01

191

Cloud removal for remotely sensed images by similar pixel replacement guided with a spatio-temporal MRF model  

NASA Astrophysics Data System (ADS)

Cloud cover is generally present in remotely sensed images, which limits the potential of the images for ground information extraction. Therefore, removing the clouds and recovering the ground information for the cloud-contaminated images is often necessary in many applications. In this paper, an effective method based on similar pixel replacement is developed to solve this task. A missing pixel is filled using an appropriate similar pixel within the remaining region of the target image. A multitemporal image is used as the guidance to locate the similar pixels. A pixel-offset based spatio-temporal Markov random fields (MRF) global function is built to find the most suitable similar pixel. The proposed method was tested on MODIS and Landsat images and their land surface temperature products, and the experiments verify that the proposed method can achieve highly accurate results and is effective at dealing with the obvious atmospheric and seasonal differences between multitemporal images.

Cheng, Qing; Shen, Huanfeng; Zhang, Liangpei; Yuan, Qiangqiang; Zeng, Chao

2014-06-01

192

Infrared Cloud Imager Development for Atmospheric Optical Communication Characterization, and Measurements at the JPL Table Mountain Facility  

NASA Astrophysics Data System (ADS)

The continuous demand for high data return in deep space and near-Earth satellite missions has led NASA and international institutions to consider alternative technologies for high-data-rate communications. One solution is the establishment of wide-bandwidth Earth-space optical communication links, which require (among other things) a nearly obstruction-free atmospheric path. Considering the atmospheric channel, the most common and most apparent impairments on Earth-space optical communication paths arise from clouds. Therefore, the characterization of the statistical behavior of cloud coverage for optical communication ground station candidate sites is of vital importance. In this article, we describe the development and deployment of a ground-based, long-wavelength infrared cloud imaging system able to monitor and characterize the cloud coverage. This system is based on a commercially available camera with a 62-deg diagonal field of view. A novel internal-shutter-based calibration technique allows radiometric calibration of the camera, which operates without a thermoelectric cooler. This cloud imaging system provides continuous day-night cloud detection with constant sensitivity. The cloud imaging system also includes data-processing algorithms that calculate and remove atmospheric emission to isolate cloud signatures, and enable classification of clouds according to their optical attenuation. Measurements of long-wavelength infrared cloud radiance are used to retrieve the optical attenuation (cloud optical depth due to absorption and scattering) in the wavelength range of interest from visible to near-infrared, where the cloud attenuation is quite constant. This article addresses the specifics of the operation, calibration, and data processing of the imaging system that was deployed at the NASA/JPL Table Mountain Facility (TMF) in California. Data are reported from July 2008 to July 2010. These data describe seasonal variability in cloud cover at the TMF site, with cloud amount (percentage of cloudy pixels) peaking at just over 51 percent during February, of which more than 60 percent had optical attenuation exceeding 12 dB at wavelengths in the range from the visible to the near-infrared. The lowest cloud amount was found during August, averaging 19.6 percent, and these clouds were mostly optically thin, with low attenuation.

Nugent, P. W.; Shaw, J. A.; Piazzolla, S.

2013-02-01

193

Evaluating EUV mask pattern imaging with two EUV microscopes  

SciTech Connect

Aerial image measurement plays a key role in the development of patterned reticles for each generation of lithography. Studying the field transmitted (reflected) from EUV masks provides detailed information about potential disruptions caused by mask defects, and the performance of defect repair strategies, without the complications of photoresist imaging. Furthermore, by measuring the continuously varying intensity distribution instead of a thresholded, binary resist image, aerial image measurement can be used as feedback to improve mask and lithography system modeling methods. Interest in EUV, at-wavelength, aerial image measurement lead to the creation of several research tools worldwide. These tools are used in advanced mask development work, and in the evaluation of the need for commercial at-wavelength inspection tools. They describe performance measurements of two such tools, inspecting the same EUV mask in a series of benchmarking tests that includes brightfield and darkfield patterns. One tool is the SEMATECH Berkeley Actinic Inspection Tool (AIT) operating on a bending magnet beamline at Lawrence Berkeley National Laboratory's Advanced Light Source. The AIT features an EUV Fresnel zoneplate microscope that emulates the numerical aperture of a 0.25-NA stepper, and projects the aerial image directly onto a CCD camera, with 700x magnification. The second tool is an EUV microscope (EUVM) operating at the NewSUBARU synchrotron in Hyogo, Japan. The NewSUBARU tool projects the aerial image using a reflective, 30x Schwarzschild objective lens, followed by a 10-200x x-ray zooming tube. The illumination conditions and the imaging etendue are different for the two tools. The benchmarking measurements were used to determine many imaging and performance properties of the tools, including resolution, modulation transfer function (MTF), aberration magnitude, aberration field-dependence (including focal-plane tilt), illumination uniformity, line-edge roughness, and flare. These measurements reveal the current state of the art in at-wavelength inspection performance, and will be a useful reference as performance improves over time.

Goldberg, Kenneth A.; Takase, Kei; Naulleau, Patrick P.; Han, Hakseung; Barty, Anton; Kinoshita, Hiroo; Hamamoto, Kazuhiro

2008-02-26

194

Partial difference operators on weighted graphs for image processing on surfaces and point clouds.  

PubMed

Partial difference equations (PDEs) and variational methods for image processing on Euclidean domains spaces are very well established because they permit to solve a large range of real computer vision problems. With the recent advent of many 3D sensors, there is a growing interest in transposing and solving PDEs on surfaces and point clouds. In this paper, we propose a simple method to solve such PDEs using the framework of PDEs on graphs. This latter approach enables us to transcribe, for surfaces and point clouds, many models and algorithms designed for image processing. To illustrate our proposal, three problems are considered: 1) p -Laplacian restoration and inpainting; 2) PDEs mathematical morphology; and 3) active contours segmentation. PMID:25020095

Lozes, Francois; Elmoataz, Abderrahim; Lezoray, Olivier

2014-09-01

195

BOREAS AFM-6 NOAA/ETL 35 GHz Cloud/Turbulence Radar GIF Images  

NASA Technical Reports Server (NTRS)

The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Administration/Environment Technology Laboratory (NOAA/ETL) operated a 35-GHz cloud-sensing radar in the Northern Study Area (NSA) near the Old Jack Pine (OJP) tower from 16 Jul 1994 to 08 Aug 1994. This data set contains a time series of GIF images that show the structure of the lower atmosphere. The NOAA/ETL 35-GHz cloud/turbulence radar GIF images are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

Martner, Brooks E.; Newcomer, Jeffrey A. (Editor); Hall, Forrest G.; Smith, David E. (Technical Monitor)

2000-01-01

196

Molecular Hydrogen Images of Star Forming Regions in the Magellanic Clouds  

NASA Astrophysics Data System (ADS)

The Large and Small Magellanic Clouds exhibit a variety of star formation physics with multiple phase components in low metallicity, gas rich environments. The 10 K, 100 K, and 104 K regimes are well explored. We are imaging LMC and SMC star forming regions in 2.12 micron H2 emission which arises in the 1000 K transition zone of molecular clouds. This is an NOAO Survey program using the widefield IR camera NEWFIRM on the CTIO 4-m Blanco telescope during its limited southern deployment. The data set will have immediate morphological applications and will provide target selection for followup infrared spectroscopy. We will provide a public archive of fully calibrated images with no proprietary period. NOAO is operated by the Association of Universities for Research in Astronomy, under cooperative agreement with the National Science Foundation.

Probst, Ronald G.; Barba, R.; Bolatto, A.; Chu, Y.; Points, S.; Rubio, M.; Smith, C.

2011-01-01

197

Cloud patterns lee of Hawaii Island: A synthesis of satellite observations and numerical simulation  

NASA Astrophysics Data System (ADS)

Standing well above the trade wind inversion, Hawaii Island (maximum elevation ˜4.2 km) splits the northeast trade winds and induces a westerly reverse flow in the wake. Satellite observations and regional model simulations are used to investigate circulation effects on lee cloud formation during summer. Over the island, the cloud distribution is consistent with orographic-induced vertical motions. Over the lee ocean, our analysis reveals a cloud band that extends southwestward over a few tens of kilometers from the southwest coast of the island. This southwest lee cloud band is most pronounced in the afternoon, anchored by strong convergence and maintained by in situ cloud production in the upward motion. Such an offshore cloud band is not found off the northwest coast, an asymmetry possibly due to the Coriolis effect on the orographic flow. Off the Kona coast, the dynamically induced westerly reverse flow keeps the wake cool and nearly free of clouds during the day. Along the Kona coast, clouds are blown offshore from the island by the easterly trades in the afternoon in a layer above the reverse flow. Deprived of in situ production, these afternoon Kona coast clouds dissipate rapidly offshore. At night, the offshore land/valley breezes converge onto the onshore reverse flow, and a cloud deck forms on and off the Kona coast, bringing nighttime rain as observed at land stations. To illustrate the circulation effect, lee cloud formation is compared between tall Hawaii and short Kauai/Oahu Islands, which feature the flow-around and flow-over regimes, respectively. Effects of trade wind strength on the leeside cloudiness are also studied.

Yang, Yang; Xie, Shang-Ping; Hafner, Jan

2008-08-01

198

Coherent lidar imaging of dust clouds: waveform comparison with the poly-phase (P4) modulation waveform  

Microsoft Academic Search

A dust or aerosol cloud represents a convenient target to examine the capabilities of range-resolved Doppler and intensity (RRDI) or inverse synthetic aperture ladar (ISAR) imaging coherent laser radar, known as coherent \\

Douglas G. Youmans

2008-01-01

199

The Large Magellanic Cloud: A Power Spectral Analysis of Spitzer Images  

Microsoft Academic Search

\\u000a We present a power spectral analysis of Spitzer images of the Large Magellanic Cloud.The power spectra of the FIR emission\\u000a show two different power laws.At larger scales (kpc) the slope is ~ ?1.6, while at smaller ones (tens to few hundreds of parsecs)\\u000a the slope is steeper, with avalue ~ ?2.9.The break occurs at a scale ~ 100 ? 200

Ivânio Puerari; David L. Block; Bruce G. Elmegreen; Frédéric Bournaud

200

The Large Magellanic Cloud: A Power Spectral Analysis of Spitzer Images  

Microsoft Academic Search

We present a power spectral analysis of Spitzer images of the Large Magellanic Cloud.The power spectra of the FIR emission show two different power laws.At larger scales (kpc) the slope is ~ -1.6, while at smaller ones (tens to few hundreds of parsecs) the slope is steeper, with avalue ~ -2.9.The break occurs at a scale ~ 100 - 200

Ivânio Puerari; David L. Block; Bruce G. Elmegreen; Frédéric Bournaud

2010-01-01

201

Holographic images reconstructed from GMR-based fringe pattern  

NASA Astrophysics Data System (ADS)

We have developed a magneto-optical spatial light modulator (MOSLM) using giant magneto-resistance (GMR) structures for realizing a holographic three-dimensional (3D) display. For practical applications, reconstructed image of hologram consisting of GMR structures should be investigated in order to study the feasibility of the MOSLM. In this study, we fabricated a hologram with GMR based fringe-pattern and demonstrated a reconstructed image. A fringe-pattern convolving a crossshaped image was calculated by a conventional binary computer generated hologram (CGH) technique. The CGH-pattern has 2,048 × 2,048 with 5 ?m pixel pitch. The GMR stack consists of a Tb-Fe-Co/CoFe pinned layer, a Ag spacer, a Gd-Fe free layer for light modulation, and a Ru capping layer, was deposited by dc-magnetron sputtering. The GMR hologram was formed using photo-lithography and Krion milling processes, followed by the deposition of a Tb-Fe-Co reference layer with large coercivity and the same Kerr-rotation angle compared to the free layer, and a lift-off process. The reconstructed image of the ON-state was clearly observed and successfully distinguished from the OFF-state by switching the magnetization direction of the free-layer with an external magnetic field. These results indicate the possibility of realizing a holographic 3D display by the MOSLM using the GMR structures.

Kato, Daisuke; Aoshima, Kenichi; Machida, Kenji; Emoto, Akira; Kinjo, Hidekazu; Kuga, Kiyoshi; Ono, Hiroshi; Ishibashi, Takayuki; Kikuchi, Hiroshi; Shimidzu, Naoki

2013-01-01

202

Local mesh patterns versus local binary patterns: biomedical image indexing and retrieval.  

PubMed

In this paper, a new image indexing and retrieval algorithm using local mesh patterns are proposed for biomedical image retrieval application. The standard local binary pattern encodes the relationship between the referenced pixel and its surrounding neighbors, whereas the proposed method encodes the relationship among the surrounding neighbors for a given referenced pixel in an image. The possible relationships among the surrounding neighbors are depending on the number of neighbors, P. In addition, the effectiveness of our algorithm is confirmed by combining it with the Gabor transform. To prove the effectiveness of our algorithm, three experiments have been carried out on three different biomedical image databases. Out of which two are meant for computer tomography (CT) and one for magnetic resonance (MR) image retrieval. It is further mentioned that the database considered for three experiments are OASIS-MRI database, NEMA-CT database, and VIA/I-ELCAP database which includes region of interest CT images. The results after being investigated show a significant improvement in terms of their evaluation measures as compared to LBP, LBP with Gabor transform, and other spatial and transform domain methods. PMID:24235315

Murala, Subrahmanyam; Wu, Q M Jonathan

2014-05-01

203

Mitigating illumination gradients in a SAR image based on the image data and antenna beam pattern  

SciTech Connect

Illumination gradients in a synthetic aperture radar (SAR) image of a target can be mitigated by determining a correction for pixel values associated with the SAR image. This correction is determined based on information indicative of a beam pattern used by a SAR antenna apparatus to illuminate the target, and also based on the pixel values associated with the SAR image. The correction is applied to the pixel values associated with the SAR image to produce corrected pixel values that define a corrected SAR image.

Doerry, Armin W.

2013-04-30

204

Component pattern analysis of chemicals using multispectral THz imaging system  

NASA Astrophysics Data System (ADS)

We have developed a novel basic technology for terahertz (THz) imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral transillumination images, using absorption spectra previously measured with a widely tunable THz-wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.

Kawase, Kodo; Ogawa, Yuichi; Watanabe, Yuki

2004-04-01

205

Multi-Scale Fractal Analysis of Image Texture and Pattern  

NASA Technical Reports Server (NTRS)

Fractals embody important ideas of self-similarity, in which the spatial behavior or appearance of a system is largely independent of scale. Self-similarity is defined as a property of curves or surfaces where each part is indistinguishable from the whole, or where the form of the curve or surface is invariant with respect to scale. An ideal fractal (or monofractal) curve or surface has a constant dimension over all scales, although it may not be an integer value. This is in contrast to Euclidean or topological dimensions, where discrete one, two, and three dimensions describe curves, planes, and volumes. Theoretically, if the digital numbers of a remotely sensed image resemble an ideal fractal surface, then due to the self-similarity property, the fractal dimension of the image will not vary with scale and resolution. However, most geographical phenomena are not strictly self-similar at all scales, but they can often be modeled by a stochastic fractal in which the scaling and self-similarity properties of the fractal have inexact patterns that can be described by statistics. Stochastic fractal sets relax the monofractal self-similarity assumption and measure many scales and resolutions in order to represent the varying form of a phenomenon as a function of local variables across space. In image interpretation, pattern is defined as the overall spatial form of related features, and the repetition of certain forms is a characteristic pattern found in many cultural objects and some natural features. Texture is the visual impression of coarseness or smoothness caused by the variability or uniformity of image tone or color. A potential use of fractals concerns the analysis of image texture. In these situations it is commonly observed that the degree of roughness or inexactness in an image or surface is a function of scale and not of experimental technique. The fractal dimension of remote sensing data could yield quantitative insight on the spatial complexity and information content contained within these data. A software package known as the Image Characterization and Modeling System (ICAMS) was used to explore how fractal dimension is related to surface texture and pattern. The ICAMS software was verified using simulated images of ideal fractal surfaces with specified dimensions. The fractal dimension for areas of homogeneous land cover in the vicinity of Huntsville, Alabama was measured to investigate the relationship between texture and resolution for different land covers.

Emerson, Charles W.

1998-01-01

206

3D CARS image reconstruction and pattern recognition on SHG images  

NASA Astrophysics Data System (ADS)

Nonlinear optical imaging techniques based e.g. on coherent anti-Stokes Raman scattering (CARS) or second-harmonic generation (SHG) show great potential for in-vivo investigations of tissue. While the microspectroscopic imaging tools are established, automized data evaluation, i.e. image pattern recognition and automized image classification, of nonlinear optical images still bares great possibilities for future developments towards an objective clinical diagnosis. This contribution details the capability of nonlinear microscopy for both 3D visualization of human tissues and automated discrimination between healthy and diseased patterns using ex-vivo human skin samples. By means of CARS image alignment we show how to obtain a quasi-3D model of a skin biopsy, which allows us to trace the tissue structure in different projections. Furthermore, the potential of automated pattern and organization recognition to distinguish between healthy and keloidal skin tissue is discussed. A first classification algorithm employs the intrinsic geometrical features of collagen, which can be efficiently visualized by SHG microscopy. The shape of the collagen pattern allows conclusions about the physiological state of the skin, as the typical wavy collagen structure of healthy skin is disturbed e.g. in keloid formation. Based on the different collagen patterns a quantitative score characterizing the collagen waviness - and hence reflecting the physiological state of the tissue - is obtained. Further, two additional scoring methods for collagen organization, respectively based on a statistical analysis of the mutual organization of fibers and on FFT, are presented.

Medyukhina, Anna; Vogler, Nadine; Latka, Ines; Dietzek, Benjamin; Cicchi, Riccardo; Pavone, Francesco S.; Popp, Jürgen

2012-05-01

207

IMAGE RELEASE: New Hydrogen Clouds in the M81 Group of Galaxies  

NASA Astrophysics Data System (ADS)

A composite radio-optical image shows five new clouds of hydrogen gas discovered using the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT). The spiral galaxy M81 and its satellite, M82, are seen in visible light (white); intergalactic hydrogen gas revealed by the GBT is shown in red; and additional hydrogen gas earlier detected by the Very Large Array is shown in green. The M81 Group of galaxies, 11.8 million light-years from Earth, are interacting gravitationally with each other, as shown clearly by the gas streaming among them. The newly-discovered gas clouds, each containing from 14 to 57 million times the mass of our Sun, are similar to gas clouds also found near our own Milky Way Galaxy. Astronomers analyzing these M81 Group clouds conclude that they are likely remnants of earlier interactions among the galaxies and that this indicates that their analogs near the Milky Way had a similar origin. The research team is: Katie Chynoweth, a graduate student at Vanderbilt University; Glen Langston of the National Radio Astronomy Observatory (NRAO); Min Yun of the University of Massachusetts; Felix J. Lockman of NRAO; Kate Rubin of Lick Observatory; and Sarah Scoles of Cornell University. The astronomers presented their findings to the American Astronomical Society's meeting in Austin, Texas. Credit: Chynoweth et al., NRAO/AUI/NSF, Digital Sky Survey. The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

2008-01-01

208

Imaging spatial correlations of Rydberg excitations in cold atom clouds  

NASA Astrophysics Data System (ADS)

We measure correlations between excitation positions in cold Rydberg gases. We have previously observedootnotetextmark[2] Rydberg-blockade-induced structures in the Rydberg pair correlation function similar to those predicted in.ootnotetextmark[3] Here, we study the effect of Coulomb repulsion after field ionization, which could possibly influence the pair correlation measurement. We have simulated the ion trajectories in our chamber and determined that Coulomb repulsion did not play a role in any of our previous experiments. However, with higher magnification we expect to observe this effect as well. In the experiment, we already have obtained a magnification increase by about a factor of two, and progress towards even higher magnification is still being made. We will report on our progress in imaging smaller structures in the pair correlation function, induced by Coulomb repulsion and possibly by adiabatic Rydberg crystal formation.ootnotetextmark[4] ootnotetext[2]A. Schwarzkopf et al. Phys. Rev. Lett. 107, no. 10 (2011): 103001. ootnotetext[3]F. Robicheaux and J. Hernandez. Phys. Rev. A 72, 63403, 1-4 (2005). ootnotetext[4]T. Pohl et al. Phys. Rev. Lett. 104, no. 4 (January 27, 2010): 043002.

Schwarzkopf, Andrew; Anderson, David; Raithel, Georg

2012-06-01

209

Cassini imaging of Titan's high-latitude lakes, clouds, and south-polar surface changes  

NASA Astrophysics Data System (ADS)

Cassini's Imaging Science Subsystem (ISS) has been observing Titan since April 2004, compiling a nearly global surface map and monitoring the surface and atmosphere for activity. Early images of the south-polar region revealed numerous dark surface features and contemporaneous convective cloud systems, suggesting the presence of hydrocarbon lakes similar to those later detected at Titan's North Pole. Intriguingly, repeated south-polar imaging by ISS revealed differences consistent with ponding of hydrocarbon liquids on the surface due to precipitation from a large storm. More recent ISS images of high northern latitudes illustrate the full extents (>500,000 km2) of hydrocarbon seas, sections of which have been observed by Cassini's RADAR. These observations demonstrate dynamic processes at work on Titan and that the poles harbor liquid-hydrocarbon reservoirs, the extents of which differ from pole to pole and which may be coupled to seasonally varying circulation.

Turtle, E. P.; Perry, J. E.; McEwen, A. S.; Del Genio, A. D.; Barbara, J.; West, R. A.; Dawson, D. D.; Porco, C. C.

2009-01-01

210

Multi Spectral Pushbroom Imaging Radiometer (MPIR) for remote sensing cloud studies  

SciTech Connect

A Multi Spectral Pushbroom Imaging Radiometer (MPIR) has been developed as are relatively inexpensive ({approximately}$IM/copy), well-calibrated,imaging radiometer for aircraft studies of cloud properties. The instrument is designed to fly on an Unmanned Aerospace Vehicle (UAV) platform at altitudes from the surface up to 20 km. MPIR is being developed to support the Unmanned Aerospace Vehicle portion of the Department of Energy`s Atmospheric Radiation Measurements program (ARM/UAV). Radiation-cloud interactions are the dominant uncertainty in the current General Circulation Models used for atmospheric climate studies. Reduction of this uncertainty is a top scientific priority of the US Global Change Research Program and the ARM program. While the DOE`s ARM program measures a num-ber of parameters from the ground-based Clouds and Radiation Testbed sites, it was recognized from the outset that other key parameters are best measured by sustained airborne data taking. These measurements are critical in our understanding of global change issues as well as for improved atmospheric and near space weather forecasting applications.

Phipps, G.S.; Grotbeck, C.L.

1995-10-01

211

Day/night whole sky imagers for 24-h cloud and sky assessment: history and overview.  

PubMed

A family of fully automated digital whole sky imagers (WSIs) has been developed at the Marine Physical Laboratory over many years, for a variety of research and military applications. The most advanced of these, the day/night whole sky imagers (D/N WSIs), acquire digital imagery of the full sky down to the horizon under all conditions from full sunlight to starlight. Cloud algorithms process the imagery to automatically detect the locations of cloud for both day and night. The instruments can provide absolute radiance distribution over the full radiance range from starlight through daylight. The WSIs were fielded in 1984, followed by the D/N WSIs in 1992. These many years of experience and development have resulted in very capable instruments and algorithms that remain unique. This article discusses the history of the development of the D/N WSIs, system design, algorithms, and data products. The paper cites many reports with more detailed technical documentation. Further details of calibration, day and night algorithms, and cloud free line-of-sight results will be discussed in future articles. PMID:23478763

Shields, Janet E; Karr, Monette E; Johnson, Richard W; Burden, Art R

2013-03-10

212

Deep Convective Clouds  

NSDL National Science Digital Library

Convective clouds are clouds that develop vertically appearing like big stacks of clouds. One very common example is cumulonimbus clouds. Convective clouds are commonly connected to stormy weather. Monthly Cloud Coverage for Deep Convective Cloud data can be used to predict patterns in weather. The specific pattern associated with this data is tracking and predicting thunderstorms. In this lesson, the students will take a look at the Monthly Cloud Coverage for Deep Convective Cloud data, and name one month of the year 'Thunderstorm Season' for their continent.

213

Spatial current patterns, dephasing and current imaging in graphene nanoribbons  

NASA Astrophysics Data System (ADS)

Using the non-equilibrium Keldysh Green's function formalism, we investigate the local, non-equilibrium charge transport in graphene nanoribbons (GNRs). In particular, we demonstrate that the spatial current patterns associated with discrete transmission resonances sensitively depend on the GNRs' geometry, size and aspect ratio, the location and number of leads and the presence of dephasing. We identify a relation between the spatial form of the current patterns, and the number of degenerate energy states participating in the charge transport. Furthermore, we demonstrate a principle of superposition for the conductance and spatial current patterns in multiple-lead configurations. We demonstrate that scanning tunneling microscopy can be employed to image spatial current paths in GNRs with atomic resolution, providing important insight into the form of local charge transport. Finally, we investigate the effects of dephasing on the spatial current patterns, and show that with decreasing dephasing time, the current patterns evolve smoothly from those of a ballistic quantum network to those of a classical resistor network.

Mabillard, Joel; Can, Tankut; Morr, Dirk K.

2014-01-01

214

Neptune's Atmospheric Circulation and Cloud Morphology: Changes Revealed by 1998 HST Imaging  

NASA Astrophysics Data System (ADS)

On 11-12 August 1998, we imaged Neptune using the Hubble Space Telescope WFPC2 CCD camera and NICMOS InSb camera to obtain high-spatial-resolution, absolutely calibrated imagery from the visible through the near infrared. We used nine HST orbits to intensively sample one rotation of Neptune, and four additional orbits to sample cloud evolution and motions one and two rotations later. In 1998 Neptune displayed more bright cloud features at southern mid-latitudes (mainly at 30°S and 45°S) than in 1996, producing small, but significant, increases in Neptune's disk-integrated albedo of 1.4±1, 1.9±1, and 9.5±1% for F467M, F673N, and F850LP filters respectively. Averages over longitude regions relatively free of discrete bright clouds did not show substantial brightness changes for most filters. Although we were unable to directly confirm the continued presence in 1998 of the 1996 Northern Great Dark Spot NGDS-32, we did find what we believe to be its bright northern companion cloud at 39°N. The increased extent of both northern and southern companions in 1998 may have obscured the normally dark core of this circulation feature. The 1996 Great Dark Spot NGDS-15 was not visible in 1998. The 1996 dark circumpolar band near 60°-70°S was present in 1998, with somewhat enhanced contrast. Significant evolution of cloud features was found over short time intervals of one and two rotations of Neptune, especially at 31°S, 45°S, and 70°S. Cloud motions in 1998 agree relatively well with the 1989 Voyager smoothed profile of L. A. Sromovsky et al. (1983, Icarus105, 110-141), with some exceptions associated with bright companion clouds, and with small but significant deviations that are consistent with those observed in 1995 and 1996 (Sromovsky et al. 2001, Icarus149, 459-488). These wind profile deviations contribute important modifications to the potential vorticity gradients that control latitudinal drift rates of GDS-scale vortices on Neptune (according to numerical simulations of R. P. LeBeau and T. E. Dowling (1998, Icarus132, 239-265)). However, these modifications alone do not explain the zero latitudinal drift of 1996 NGDS-32.

Sromovsky, L. A.; Fry, P. M.; Dowling, T. E.; Baines, K. H.; Limaye, S. S.

2001-04-01

215

Low Clouds  

article title:  Indian Ocean Clouds     View Larger Image This image of clouds over the southern Indian Ocean was acquired on July 23, 2007 by one of the backward (northward)-viewing ... NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, D.C. The Terra spacecraft is managed ...

2013-04-19

216

Graphene electrically reconfigurable patterns for THz imaging applications  

NASA Astrophysics Data System (ADS)

THz waves are attractive for several imaging applications, since they can propagate through non metallic media such as paper, cloth, plastics, and ceramics, and do not scatter over nano-scale defects or ionize the material under imaging -as might shorter wavelengths do- while offering an image resolution similar to that of the human eye. In this work we propose and experimentally demonstrate electrically reconfigurable patterns for single-pixel terahertz imaging based on arrays of graphene THz electro-absorption modulators. In an optical setup, in conjunction with mirrors, the modulator array can transform the output radiation from a CW THz source into a pixelated and collimated beam of illumination. Single-atom-thick graphene is employed as the active element of these modulators, achieving a modulation of the THz wave reflectance 50% with a potential modulation depth approaching 100% (i.e. each region of the pixelated collimated beam can be potentially completely turned-off). Although the proof-of-concept device here discussed only consists of 4x4 elements, we foresee that this technology can enable low-cost video rate THz imaging systems.

Sensale-Rodriguez, Berardi; Rafique, Subrina; Yan, Rusen; Zhu, Mingda; Protasenko, Vladimir; Jena, Debdeep; Liu, Lei; Xing, Huili Grace

2013-03-01

217

Classification of texture patterns in CT lung imaging  

NASA Astrophysics Data System (ADS)

Since several lung diseases can be potentially diagnosed based on the patterns of lung tissue observed in medical images, automated texture classification can be useful in assisting the diagnosis. In this paper, we propose a methodology for discriminating between various types of normal and diseased lung tissue in computed tomography (CT) images that utilizes Vector Quantization (VQ), an image compression technique, to extract discriminative texture features. Rather than focusing on images of the entire lung, we direct our attention to the extraction of local descriptors from individual regions of interest (ROIs) as determined by domain experts. After determining the ROIs, we generate "locally optimal" codebooks representing texture features of each region using the Generalized Lloyd Algorithm. We then utilize the codeword usage frequency of each codebook as a discriminative feature vector for the region it represents. We compare k-nearest neighbor, support vector machine and neural network classification approaches using the normalized histogram intersection as a similarity measure. The classification accuracy reached up to 98% for certain experimental settings, indicating that our approach may potentially assist clinicians in the interpretation of lung images and facilitate the investigation of relationships among structure, texture and function or pathology related to several lung diseases.

Nuzhnaya, Tatyana; Megalooikonomou, Vasileios; Ling, Haibin; Kohn, Mark; Steiner, Robert

2011-03-01

218

Magnetic resonance imaging pattern recognition in hypomyelinating disorders.  

PubMed

Hypomyelination is observed in the context of a growing number of genetic disorders that share clinical characteristics. The aim of this study was to determine the possible role of magnetic resonance imaging pattern recognition in distinguishing different hypomyelinating disorders, which would facilitate the diagnostic process. Only patients with hypomyelination of known cause were included in this retrospective study. A total of 112 patients with Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus-Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis, Salla disease and fucosidosis were included. The brain scans were rated using a standard scoring list; the raters were blinded to the diagnoses. Grouping of the patients was based on cluster analysis. Ten clusters of patients with similar magnetic resonance imaging abnormalities were identified. The most important discriminating items were early cerebellar atrophy, homogeneity of the white matter signal on T(2)-weighted images, abnormal signal intensity of the basal ganglia, signal abnormalities in the pons and additional T(2) lesions in the deep white matter. Eight clusters each represented mainly a single disorder (i.e. Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, infantile GM1 and GM2 gangliosidosis, Pelizaeus-Merzbacher-like disease and fucosidosis); only two clusters contained multiple diseases. Pelizaeus-Merzbacher-like disease was divided between two clusters and Salla disease did not cluster at all. This study shows that it is possible to separate patients with hypomyelination disorders of known cause in clusters based on magnetic resonance imaging abnormalities alone. In most cases of Pelizaeus-Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus-Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis and fucosidosis, the imaging pattern gives clues for the diagnosis. PMID:20881161

Steenweg, Marjan E; Vanderver, Adeline; Blaser, Susan; Bizzi, Alberto; de Koning, Tom J; Mancini, Grazia M S; van Wieringen, Wessel N; Barkhof, Frederik; Wolf, Nicole I; van der Knaap, Marjo S

2010-10-01

219

Magnetic resonance imaging pattern recognition in hypomyelinating disorders  

PubMed Central

Hypomyelination is observed in the context of a growing number of genetic disorders that share clinical characteristics. The aim of this study was to determine the possible role of magnetic resonance imaging pattern recognition in distinguishing different hypomyelinating disorders, which would facilitate the diagnostic process. Only patients with hypomyelination of known cause were included in this retrospective study. A total of 112 patients with Pelizaeus–Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus–Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis, Salla disease and fucosidosis were included. The brain scans were rated using a standard scoring list; the raters were blinded to the diagnoses. Grouping of the patients was based on cluster analysis. Ten clusters of patients with similar magnetic resonance imaging abnormalities were identified. The most important discriminating items were early cerebellar atrophy, homogeneity of the white matter signal on T2-weighted images, abnormal signal intensity of the basal ganglia, signal abnormalities in the pons and additional T2 lesions in the deep white matter. Eight clusters each represented mainly a single disorder (i.e. Pelizaeus–Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, infantile GM1 and GM2 gangliosidosis, Pelizaeus–Merzbacher-like disease and fucosidosis); only two clusters contained multiple diseases. Pelizaeus–Merzbacher-like disease was divided between two clusters and Salla disease did not cluster at all. This study shows that it is possible to separate patients with hypomyelination disorders of known cause in clusters based on magnetic resonance imaging abnormalities alone. In most cases of Pelizaeus–Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus–Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis and fucosidosis, the imaging pattern gives clues for the diagnosis.

Steenweg, Marjan E.; Vanderver, Adeline; Blaser, Susan; Bizzi, Alberto; de Koning, Tom J.; Mancini, Grazia M. S.; van Wieringen, Wessel N.; Barkhof, Frederik; Wolf, Nicole I.

2010-01-01

220

Cirrus cloud characteristics derived from volume imaging lidar, high spectral resolution lidar, HIS radiometer, and satellite  

NASA Technical Reports Server (NTRS)

Preliminary measurement results are presented from the Cirrus Remote Sensing Pilot Experiment which used a unique suite of instruments to simultaneously retrieve cirrus cloud visible and IR optical properties, while addressing the disparities between satellite volume averages and local point measurements. The experiment employed a ground-based high resolution interferometer sounder (HIS) and a second Fourier transform spectrometer to measure the spectral radiance in the 4-20 micron band, a correlated high spectral resolution lidar, a volume imaging lidar, a CLASS radiosonde system, the Scripps Whole Sky Imager, and multispectral VAS, HIRS, and AVHRR satellite data from polar orbiting and geostationary satellites. Data acquired during the month long experiment included continuous daytime monitoring with the Whole Sky Imager.

Grund, Christian J.; Ackerman, Steven A.; Eloranta, Edwin W.; Knutsen, Robert O.; Revercomb, Henry E.; Smith, William L.; Wylie, Donald P.

1990-01-01

221

Optical imaging of cloud-to-stratosphere/mesosphere lightning over the Amazon Basin (CS/LAB)  

NASA Technical Reports Server (NTRS)

The purpose of the CS/LAB project was to obtain images of cloud to stratosphere lightning discharges from aboard NASA's DC-8 Airborne Laboratory while flying in the vicinity of thunderstorms over the Amazon Basin. We devised a low light level imaging package as an add-on experiment to an airborne Laboratory deployment to South America during May-June, 1993. We were not successful in obtaining the desired images during the South American deployment. However, in a follow up flight over the American Midwest during the night of July 8-9, 1993 we recorded nineteen examples of the events over intense thunderstorms. From the observations were estimated absolute brightness, terminal altitudes, flash duration, horizontal extents, emission volumes, and frequencies relative to negative and positive ground strokes.

Sentman, Davis D.; Wescott, Eugene M.

1995-01-01

222

Spatial-temporal change in precipitation patterns based on the cloud model across the Wei River Basin, China  

NASA Astrophysics Data System (ADS)

It is of significant importance to investigate the spatial-temporal change in precipitation patterns due to its great effects on droughts, floods, soil erosion and water resource management. A complete investigation of precipitation structure and its distribution pattern based on daily precipitation covering 1960-2005 at 21 meteorological stations in the Wei River Basin has been performed. In order to comprehensively and objectively describe the changing pattern of precipitation, the cloud model is employed to quantitatively analyse the average, uniformity and stability of precipitation. Results indicate the following: (1) the occurrence of different precipitation durations exhibits a positive exponential curve with the decrease in precipitation durations, and 1-3-day events are the predominant precipitation events which have an increasing trend; (2) precipitation and its non-uniformity is increasingly reducing, while its stability increases initially then decreases; (3) mean precipitation reduces from southeast to northwest, and the precipitation of the Guanzhong Plain has a low uniformity and stability due to its location and increasingly intensifying human activities. The cloud model provides a new idea and quantitative measure for the evaluation of the uniformity and stability of precipitation.

Huang, Shengzhi; Hou, Beibei; Chang, Jianxia; Huang, Qiang; Chen, Yutong

2014-05-01

223

Two Methods for Retrieving UV Index for All Cloud Conditions from Sky Imager Products or Total SW Radiation Measurements.  

PubMed

Cloud effects on UV Index (UVI) and total solar radiation (TR) as a function of cloud cover and sunny conditions (from sky images) as well as of solar zenith angle (SZA) are assessed. These analyses are undertaken for a southern-hemisphere mid-latitude site where a 10-years dataset is available. It is confirmed that clouds reduce TR more than UV, in particular for obscured Sun conditions, low cloud fraction (<60%) and large SZA (>60°). Similarly, local short-time enhancement effects are stronger for TR than for UV, mainly for visible Sun conditions, large cloud fraction and large SZA. Two methods to estimate UVI are developed: (1) from sky imaging cloud cover and sunny conditions, and (2) from TR measurements. Both methods may be used in practical applications, although Method 2 shows overall the best performance, as TR allows considering cloud optical properties. The mean absolute (relative) differences of Method 2 estimations with respect to measured values are 0.17 UVI units (6.7%, for 1 min data) and 0.79 Standard Erythemal Dose (SED) units (3.9%, for daily integrations). Method 1 shows less accurate results but it is still suitable to estimate UVI: mean absolute differences are 0.37 UVI units (15%) and 1.6 SED (8.0%). PMID:24645969

Badosa, Jordi; Calbó, Josep; Mckenzie, Richard; Liley, Ben; González, Josep-Abel; Forgan, Bruce; Long, Charles N

2014-07-01

224

High-resolution imaging and target designation through clouds or smoke  

DOEpatents

A method and system of combining gated intensifiers and advances in solid-state, short-pulse laser technology, compact systems capable of producing high resolution (i.e., approximately less than 20 centimeters) optical images through a scattering medium such as dense clouds, fog, smoke, etc. may be achieved from air or ground based platforms. Laser target designation through a scattering medium is also enabled by utilizing a short pulse illumination laser and a relatively minor change to the detectors on laser guided munitions.

Perry, Michael D. (Downy, CA)

2003-01-01

225

A Cost-Benefit Study of Doing Astrophysics On The Cloud: Production of Image Mosaics  

NASA Astrophysics Data System (ADS)

Utility grids such as the Amazon EC2 and Amazon S3 clouds offer computational and storage resources that can be used on-demand for a fee by compute- and data-intensive applications. The cost of running an application on such a cloud depends on the compute, storage and communication resources it will provision and consume. Different execution plans of the same application may result in significantly different costs. We studied via simulation the cost performance trade-offs of different execution and resource provisioning plans by creating, under the Amazon cloud fee structure, mosaics with the Montage image mosaic engine, a widely used data- and compute-intensive application. Specifically, we studied the cost of building mosaics of 2MASS data that have sizes of 1, 2 and 4 square degrees, and a 2MASS all-sky mosaic. These are examples of mosaics commonly generated by astronomers. We also study these trade-offs in the context of the storage and communication fees of Amazon S3 when used for long-term application data archiving. Our results show that by provisioning the right amount of storage and compute resources cost can be significantly reduced with no significant impact on application performance.

Berriman, G. B.; Good, J. C. Deelman, E.; Singh, G. Livny, M.

2009-09-01

226

Airborne Digital In-Line Holographic System for 3-D Imaging of Cloud Particles  

NASA Astrophysics Data System (ADS)

We have developed an airborne holographic instrument for obtaining cloud particle sizes and shapes and their three-dimensional spatial distribution. The primary scientific motivation for the instrument is to provide in-situ measurements of cloud particle spatial correlations, conditioned on particle size. Accurate quantification of spatial correlations at cm-scales and below has been elusive, in part because only one-dimensional spacing data have been available. The optical technique used in the instrument is based on `in-line holography,' where the same collimated light source serves as both the reference beam and the object beam. The system is completely digital, including the capture of holograms using a CCD array, transmission of the data via optical fiber, and subsequent reconstruction of the real image. During the recent IDEAS-3 field project hosted by the NCAR Research Aviation Facility the instrument was tested in flight for the first time, where holograms containing populations of cloud droplets, drizzle drops, and ice crystals were obtained.

Fugal, J. P.; Saw, E.; Sergeyev, A. V.; Shaw, R. A.

2003-12-01

227

Development of the PACS multi-angle imaging polarimeter for cloud and aerosols retrievals  

NASA Astrophysics Data System (ADS)

Passive Aerosol & Clouds Suite Polarimeter (PACS Polarimeter) belongs to a new generation of imaging multi angle polarimetric remote sensing instruments designed to provide microphysical retrieval of aerosol and cloud particles as well as the detailed characterization of the multiangular surface properties. The PACS polarimeter design is a wide field of view multispectral polarimeter, which performs an instantaneous measurement in three linear polarization channels and is able to retrieve accurate measurements of three Stokes parameters. By its design characteristics PACS is able to offer an unique angular and spatial coverage in multispectral bands. The number of angles (up to about 100) can be selected as a function of wavelength. The simultaneity of the data acquisition in the three linear polarization channels and a detailed characterization of the PACS wide FOV optics allows for the high polarimetric accuracy required for aerosol microphysical retrievals. A new calibration and characterization methodology has been developed to cover the PACS wide FOV optics and can be applied to general system. The PACS polarimeter has flown by the first time aboard the ER2 aircraft during the PODEX experiment and collected data on aerosol and clouds over multiple surface types. In this presentation, we will discuss different test cases collected during the PODEX campaign oriented to show the capabilities and potentialities of PACS VNIR polarimeter.

Fernandez Borda, R. A.; Martins, J.

2013-12-01

228

Novel video processing schemes integrating image compression and pattern recognition  

NASA Astrophysics Data System (ADS)

In comparison to present security applications, pattern recognition techniques can be categorized as 'hard' automatic target recognition (ATR) and 'soft' ATR. The first category has been established for years and deals with specific object recognition. On the other hand, the second, less established category operates on very fast object class-level recognition only. The second category usually employs very fast processing and an image database. In this paper, we introduce a novel method to integrate a compression technique based on logic data representation with soft ATR. This new compression method applies Arnold's Differential Mapping Singularities Theory in the context of 3D object projection into the 2D image plane, and takes advantage of the fact that object edges can be interpreted in terms of singularities, which can be described isomorphically by simple polynomials. Therefore, compared to state- of-the-art still image compression, such as JPEG, there is no information los in high contrast, high-dynamic range image areas; as a result, the global peak signal noise ratio can be very high By using linked edges to represent an object, it is possible to use a simple set of parameters for real-time 'soft' ATR. This publication discuses various security applications of this new scheme, which is integrated with ATR compression.

Ternovskiy, Igor V.; Jannson, Tomasz

1997-10-01

229

An adaptive OPD and dislocation prediction used characteristic of interference pattern for interference hyperspectral image compression  

Microsoft Academic Search

According to the imaging principle and characteristic of LASIS (Large Aperture Static Interference Imaging Spectrometer), we discovered that the 3D (three dimensional) image sequences formed by different interference pattern frames, which were formed in the imaging process of LASIS Interference hyperspectral image, had much stronger correlation than the original interference hyperspectral image sequences, either in 2D (two dimensional) spatial domain

Jia Wen; Caiwen Ma; Penglang Shui

2011-01-01

230

Intelligent technique to search for patterns within images in massive databases  

SciTech Connect

An image retrieval system for JET has been developed. The image database contains the images of the JET high speed visible camera. The system input is a pattern selected inside an image and the output is the group of frames (defined by their discharge numbers and time slices) that show patterns similar to the selected one. This approach is based on morphological pattern recognition and it should be emphasized that the pattern is found independently of its location in the frame. The technique encodes images into characters and, therefore, it transforms the pattern search into a character-matching problem.

Vega, J.; Murari, A.; Pereira, A.; Portas, A.; Castro, P. [JET-EFDA, Culham Science Center, OX14 3DB Abingdon (United Kingdom)

2008-10-15

231

Hierarchical test pattern composition to testing a foveal imager ASIC  

NASA Astrophysics Data System (ADS)

The aim of this work is the test of an ASIC, intended for multiresolution images generation, with high fault coverage and low number of patterns, looking for the improvement of the results obtained with other tools. The circuit includes a embedded SRAM block used to implement several internal FIFO structures. This RAM block has been generated with the 'Memory Compiler Systems' supplied by AMS, and does not includes BIST logic, so the strategy was to generate and insert the BIST logic to completely test the RAM operation. The original test algorithm proposed by the foundry support center, has been modified for a thorough verification. Also, to achieve the controllability and observability of the shadow logic connected to the RAM outputs and inputs respectively, the necessary test logic around the embedded block has been inserted. Once the test of the RAM has been guaranteed the remaining logic needs to be tested. To accomplish this task the full scan path approach has been selected, and a hierarchical bottom-up methodology has been followed to generate the test patterns. The ATPG commercial tools ( Synopsys Test Compiler) has been used only to generate the patterns for the lowest level modules of the hierarchy tree. Making the appropriate design partitioning (basically defining the modules with registered outputs), the patterns for the upper level modules can be easily composed. Several appropriate configurations for this smart partitioning has been identified and defined. Using a simple composing technique we can obtain a considerable reduction above 37% in the number of patterns with a negligible fault coverage decrease and hardware overhead.

Gonzalez, Martin; Salinas, Jose R.; Coslado, Francisco J.; Camacho, Pelegrin; Sandoval, Francisco

2003-04-01

232

Mapping low- and high-density clouds in astrophysical nebulae by imaging forbidden line emission  

NASA Astrophysics Data System (ADS)

Emission line ratios have been essential for determining physical parameters such as gas temperature and density in astrophysical gaseous nebulae. With the advent of panoramic spectroscopic devices, images of regions with emission lines related to these physical parameters can, in principle, also be produced. We show that, with observations from modern instruments, it is possible to transform images taken from density-sensitive forbidden lines into images of emission from high- and low-density clouds by applying a transformation matrix. In order to achieve this, images of the pairs of density-sensitive lines as well as the adjacent continuum have to be observed and combined. We have computed the critical densities for a series of pairs of lines in the infrared, optical, ultraviolet and X-rays bands, and calculated the pair line intensity ratios in the high- and low-density limit using a four- and five-level atom approximation. In order to illustrate the method, we applied it to Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (GMOS-IFU) data of two galactic nuclei. We conclude that this method provides new information of astrophysical interest, especially for mapping low- and high-density clouds; for this reason, we call it `the ld/hd imaging method'. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the National Science Foundation on behalf of the Gemini partnership: the National Science Foundation (United States); the Science and Technology Facilities Council (United Kingdom); the National Research Council (Canada), CONICYT (Chile); the Australian Research Council (Australia); Ministério da Ciência e Tecnologia (Brazil) and Secretaria de Ciencia y Tecnologia (Argentina). E-mail: steiner@astro.iag.usp.br

Steiner, J. E.; Menezes, R. B.; Ricci, T. V.; Oliveira, A. S.

2009-06-01

233

A QR code based zero-watermarking scheme for authentication of medical images in teleradiology cloud.  

PubMed

Healthcare institutions adapt cloud based archiving of medical images and patient records to share them efficiently. Controlled access to these records and authentication of images must be enforced to mitigate fraudulent activities and medical errors. This paper presents a zero-watermarking scheme implemented in the composite Contourlet Transform (CT)-Singular Value Decomposition (SVD) domain for unambiguous authentication of medical images. Further, a framework is proposed for accessing patient records based on the watermarking scheme. The patient identification details and a link to patient data encoded into a Quick Response (QR) code serves as the watermark. In the proposed scheme, the medical image is not subjected to degradations due to watermarking. Patient authentication and authorized access to patient data are realized on combining a Secret Share with the Master Share constructed from invariant features of the medical image. The Hu's invariant image moments are exploited in creating the Master Share. The proposed system is evaluated with Checkmark software and is found to be robust to both geometric and non geometric attacks. PMID:23970943

Seenivasagam, V; Velumani, R

2013-01-01

234

A QR Code Based Zero-Watermarking Scheme for Authentication of Medical Images in Teleradiology Cloud  

PubMed Central

Healthcare institutions adapt cloud based archiving of medical images and patient records to share them efficiently. Controlled access to these records and authentication of images must be enforced to mitigate fraudulent activities and medical errors. This paper presents a zero-watermarking scheme implemented in the composite Contourlet Transform (CT)—Singular Value Decomposition (SVD) domain for unambiguous authentication of medical images. Further, a framework is proposed for accessing patient records based on the watermarking scheme. The patient identification details and a link to patient data encoded into a Quick Response (QR) code serves as the watermark. In the proposed scheme, the medical image is not subjected to degradations due to watermarking. Patient authentication and authorized access to patient data are realized on combining a Secret Share with the Master Share constructed from invariant features of the medical image. The Hu's invariant image moments are exploited in creating the Master Share. The proposed system is evaluated with Checkmark software and is found to be robust to both geometric and non geometric attacks.

Seenivasagam, V.; Velumani, R.

2013-01-01

235

Contours Based Approach for Thermal Image and Terrestrial Point Cloud Registration  

NASA Astrophysics Data System (ADS)

Building energetic performances strongly depend on the thermal insulation. However the performance of the insulation materials tends to decrease over time which necessitates the continuous monitoring of the building in order to detect and repair the anomalous zones. In this paper, it is proposed to couple 2D infrared images representing the surface temperature of the building with 3D point clouds acquired with Terrestrial Laser Scanner (TLS) resulting in a semi-automatic approach allowing the texturation of TLS data with infrared image of buildings. A contour-based algorithm is proposed whose main features are : 1) the extraction of high level primitive is not required 2) the use of projective transform allows to handle perspective effects 3) a point matching refinement procedure allows to cope with approximate control point selection. The procedure is applied to test modules aiming at investigating the thermal properties of material.

Bennis, A.; Bombardier, V.; Thiriet, P.; Brie, D.

2013-07-01

236

Imaging Dot Patterns for Measuring Gossamer Space Structures  

NASA Technical Reports Server (NTRS)

A paper describes a photogrammetric method for measuring the changing shape of a gossamer (membrane) structure deployed in outer space. Such a structure is typified by a solar sail comprising a transparent polymeric membrane aluminized on its Sun-facing side and coated black on the opposite side. Unlike some prior photogrammetric methods, this method does not require an artificial light source or the attachment of retroreflectors to the gossamer structure. In a basic version of the method, the membrane contains a fluorescent dye, and the front and back coats are removed in matching patterns of dots. The dye in the dots absorbs some sunlight and fluoresces at a longer wavelength in all directions, thereby enabling acquisition of high-contrast images from almost any viewing angle. The fluorescent dots are observed by one or more electronic camera(s) on the Sun side, the shade side, or both sides. Filters that pass the fluorescent light and suppress most of the solar spectrum are placed in front of the camera(s) to increase the contrast of the dots against the background. The dot image(s) in the camera(s) are digitized, then processed by use of commercially available photogrammetric software.

Dorrington, A. A.; Danehy, P. M.; Jones, T. W.; Pappa, R. S.; Connell, J. W.

2005-01-01

237

A 10-year climatology of Northern Hemisphere tropical cloud plumes and their composite flow patterns  

SciTech Connect

A 10-year cool season climatology of tropical cloud plumes in the Northern Hemisphere was generated by visual inspection of infrared satellite imagery. The sample included 1062 plume events during the months of October to May for the years 1974 to 1984. The results show that the westerly ducts of the tropical eastern Pacific and central Atlantic are preferred regions for tropical cloud plume development. Composite fields of streamfunction and outgoing longwave radiation for eastern Pacific plumes indicate that both low-latitude westerlies in the planetary-scale basic-state flow and the presence of synoptic-scale transients appear to be favorable for plume formation. With a knowledge of these features, some of the interannual and intraannual variability shown in the climatology can be explained. 14 refs., 6 figs.

Iskenderian, H. [State Univ. of New York, Albany, NY (United States)] [State Univ. of New York, Albany, NY (United States)

1995-06-01

238

Buildup of electron cloud with different bunch pattern in thepresence of solenoid field  

SciTech Connect

We have augmented the code POSINST to include solenoidfields, and used it to simulate the build up of electron cloud due toelectron multipacting in the PEP-II positron ring. We find that thedistribution of electrons is strongly affected by the resonancesassociated with the cyclotron period and bunch spacing. In addition, wediscover a threshold beyond which the electron density growsexponentially until it reaches the space charge limit. The threshold doesnot depend on the bunch spacing but does depend on the positron bunchpopulation.

Cai, Y.; Pivi (SLAC), M.; Furman (LBNL), M.A.

2003-05-01

239

Understanding uncertainties in the retrieval of polar mesospheric clouds from the cloud imaging and particle size experiment in the presence of a bright Rayleigh background  

NASA Astrophysics Data System (ADS)

This paper presents a framework for understanding and quantifying the leverage available for inverting the radiance signal in order to retrieve particle size distribution mode radius and albedo from polar mesospheric clouds (PMC) observations using the cloud imaging and particle size (CIPS) instrument on board the aeronomy of ice in the mesosphere (AIM) satellite. The observed signal is a superposition of the scattering angle dependence of the cloud albedo and the Rayleigh scattered albedo controlled by ozone at the stratopause. The leverage as is defined in the paper is a way to quantify how much the net scattering angle dependence changes as a function of mode radius. The leverage is determined by decomposing the observed signal into orthogonal components which isolate the parts of the signal that are unique to changes in mode radius from those that could be due to changes in the background. This leverage is considered along with instrument noise performance to determine retrieval uncertainties and to understand minimum thresholds in the cloud retrieval parameters.

Carstens, Justin N.; Bailey, Scott M.; Lumpe, Jerry D.; Randall, Cora E.

2013-11-01

240

View angle dependence of cloud optical thicknesses retrieved by Moderate Resolution Imaging Spectroradiometer (MODIS)  

Microsoft Academic Search

This study examines whether cloud inhomogeneity influences the view angle dependence of MODIS cloud optical thickness retrieval results. The degree of cloud inhomogeneity is characterized through the local gradient in 11 mum brightness temperature. The analysis of liquid phase clouds in a 1 year long global data set of Collection 4 MODIS data reveals that while optical thickness retrievals give

Tamás Várnai; Alexander Marshak

2007-01-01

241

View angle dependence of cloud optical thicknesses retrieved by Moderate Resolution Imaging Spectroradiometer (MODIS)  

Microsoft Academic Search

This study examines whether cloud inhomogeneity influences the view angle dependence of MODIS cloud optical thickness retrieval results. The degree of cloud inhomogeneity is characterized through the local gradient in 11 ?m brightness temperature. The analysis of liquid phase clouds in a 1 year long global data set of Collection 4 MODIS data reveals that while optical thickness retrievals give

Tamás Várnai; Alexander Marshak

2007-01-01

242

Astronomy in the Cloud: Using MapReduce for Image Co-Addition  

NASA Astrophysics Data System (ADS)

In the coming decade, astronomical surveys of the sky will generate tens of terabytes of images and detect hundreds of millions of sources every night. The study of these sources will involve computation challenges such as anomaly detection and classification and moving-object tracking. Since such studies benefit from the highest-quality data, methods such as image co-addition, i.e., astrometric registration followed by per-pixel summation, will be a critical preprocessing step prior to scientific investigation. With a requirement that these images be analyzed on a nightly basis to identify moving sources such as potentially hazardous asteroids or transient objects such as supernovae, these data streams present many computational challenges. Given the quantity of data involved, the computational load of these problems can only be addressed by distributing the workload over a large number of nodes. However, the high data throughput demanded by these applications may present scalability challenges for certain storage architectures. One scalable data-processing method that has emerged in recent years is MapReduce, and in this article we focus on its popular open-source implementation called Hadoop. In the Hadoop framework, the data are partitioned among storage attached directly to worker nodes, and the processing workload is scheduled in parallel on the nodes that contain the required input data. A further motivation for using Hadoop is that it allows us to exploit cloud computing resources: i.e., platforms where Hadoop is offered as a service. We report on our experience of implementing a scalable image-processing pipeline for the SDSS imaging database using Hadoop. This multiterabyte imaging data set provides a good testbed for algorithm development, since its scope and structure approximate future surveys. First, we describe MapReduce and how we adapted image co-addition to the MapReduce framework. Then we describe a number of optimizations to our basic approach and report experimental results comparing their performance.

Wiley, K.; Connolly, A.; Gardner, J.; Krughoff, S.; Balazinska, M.; Howe, B.; Kwon, Y.; Bu, Y.

2011-03-01

243

Displacement fields from point cloud data: Application of particle imaging velocimetry to landslide geodesy  

NASA Astrophysics Data System (ADS)

Acquiring spatially continuous ground-surface displacement fields from Terrestrial Laser Scanners (TLS) will allow better understanding of the physical processes governing landslide motion at detailed spatial and temporal scales. Problems arise, however, when estimating continuous displacement fields from TLS point-clouds because reflecting points from sequential scans of moving ground are not defined uniquely, thus repeat TLS surveys typically do not track individual reflectors. Here, we implemented the cross-correlation-based Particle Image Velocimetry (PIV) method to derive a surface deformation field using TLS point-cloud data. We estimated associated errors using the shape of the cross-correlation function and tested the method's performance with synthetic displacements applied to a TLS point cloud. We applied the method to the toe of the episodically active Cleveland Corral Landslide in northern California using TLS data acquired in June 2005-January 2007 and January-May 2010. Estimated displacements ranged from decimeters to several meters and they agreed well with independent measurements at better than 9% root mean squared (RMS) error. For each of the time periods, the method provided a smooth, nearly continuous displacement field that coincides with independently mapped boundaries of the slide and permits further kinematic and mechanical inference. For the 2010 data set, for instance, the PIV-derived displacement field identified a diffuse zone of displacement that preceded by over a month the development of a new lateral shear zone. Additionally, the upslope and downslope displacement gradients delineated by the dense PIV field elucidated the non-rigid behavior of the slide.

Aryal, Arjun; Brooks, Benjamin A.; Reid, Mark E.; Bawden, Gerald W.; Pawlak, Geno R.

2012-03-01

244

Ice content of Polar Mesospheric Clouds measured by the Cloud Imaging and Particle Size (CIPS) and the Solar Occultation for Ice (SOFIE) experiments on the Aeronomy of Ice in the Mesosphere (AIM) Mission  

Microsoft Academic Search

Two experiments on the AIM spacecraft, launched in April, 2007, were designed to take complementary measurements of Polar Mesospheric Clouds (PMC) properties. The Cloud Imaging and Particle Size (CIPS) experiment measures PMC at several scattering angles with 5 km spatial resolution. The Solar Occultation for Ice Experiment (SOFIE) measures the solar extinction by PMC at the limb at 11 wavelengths.

G. E. Thomas; D. W. Rusch; M. Hervig; L. Gordley; S. M. Bailey; W. McClintock; A. W. Merkel; J. M. Russell

2008-01-01

245

Build up of electron cloud with different bunch pattern in the presence of solenoidal field  

SciTech Connect

We have augmented the code POSINST to include solenoid fields, and used it to simulate the build up of electron cloud due to electron multipacting in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition, we discover a threshold beyond which the electron density grows exponentially until it reaches the space charge limit. The threshold does not depend on the bunch spacing but does depend on the positron bunch population.

Cai, Y.; Furman, M.A.; Pivi, M.

2004-04-01

246

Noctilucent Cloud Imaging and Tomography using a Suborbital Reusable Launch Vehicle  

NASA Astrophysics Data System (ADS)

Noctilucent Clouds (NLCs) are the highest clouds in the Earth's atmosphere, residing at a mean altitude of 83 km. They have been observed since 1885 around the summer solstice and are considered to be very sensitive indicators for what is going on in the atmosphere at higher altitudes. They have been observed to both increase in brightness and frequency as well as extend to lower latitudes and it has been hypothesized that the anthropogenic causes of climatic change may be directly related to NLC presence. An experiment is currently supported through NASA's Flight Opportunities program to use a Suborbital Reusable Launch Vehicle (SRLV) to fly a manned, stabilized imager suite through an NLC layer to obtain imagery and topography data of unprecedented resolution. The campaign is targeted for July 2014 and will involve a series of flights from a high-latitude spaceport when NLC activity is observed. These data should advance our understanding of energy and momentum deposition to the upper atmosphere through enhanced observations of gravity wave perturbations, instability dynamics, and turbulent regions.

Reimuller, J. D.; Fritts, D. C.; Thomas, G. E.

2012-12-01

247

Types of Clouds  

NSDL National Science Digital Library

This is a basic lesson on clouds. Very nice photos of cumulus and cumulonimbus clouds are presented on the page as well as a description of all major cloud types and their associated weather. Two activities are presented. One invites the learner to create a cloud, while the other involves creating a collage of cloud images along with information about the weather associated with each cloud type.

Friend, Duane

248

Imaging patterns with 99mTc-PIPIDA in evaluating abdominal pain  

SciTech Connect

A random retrospective review of hepatobiliary scans on 86 adult patients with abdominal pain revealed four distinct imaging patterns: normal, cystic duct obstruction, obstructive, and sick liver pattern. A normal pattern was found to exclude acute cholecystitis and was the pattern most frequently observed.

Curtis, R.F.; Gordon, L.; Selby, J.B. Sr.

1983-11-01

249

Point cloud generation from aerial image data acquired by a quadrocopter type micro unmanned aerial vehicle and a digital still camera.  

PubMed

The objective of this investigation was to develop and investigate methods for point cloud generation by image matching using aerial image data collected by quadrocopter type micro unmanned aerial vehicle (UAV) imaging systems. Automatic generation of high-quality, dense point clouds from digital images by image matching is a recent, cutting-edge step forward in digital photogrammetric technology. The major components of the system for point cloud generation are a UAV imaging system, an image data collection process using high image overlaps, and post-processing with image orientation and point cloud generation. Two post-processing approaches were developed: one of the methods is based on Bae Systems' SOCET SET classical commercial photogrammetric software and another is built using Microsoft(®)'s Photosynth™ service available in the Internet. Empirical testing was carried out in two test areas. Photosynth processing showed that it is possible to orient the images and generate point clouds fully automatically without any a priori orientation information or interactive work. The photogrammetric processing line provided dense and accurate point clouds that followed the theoretical principles of photogrammetry, but also some artifacts were detected. The point clouds from the Photosynth processing were sparser and noisier, which is to a large extent due to the fact that the method is not optimized for dense point cloud generation. Careful photogrammetric processing with self-calibration is required to achieve the highest accuracy. Our results demonstrate the high performance potential of the approach and that with rigorous processing it is possible to reach results that are consistent with theory. We also point out several further research topics. Based on theoretical and empirical results, we give recommendations for properties of imaging sensor, data collection and processing of UAV image data to ensure accurate point cloud generation. PMID:22368479

Rosnell, Tomi; Honkavaara, Eija

2012-01-01

250

Point Cloud Generation from Aerial Image Data Acquired by a Quadrocopter Type Micro Unmanned Aerial Vehicle and a Digital Still Camera  

PubMed Central

The objective of this investigation was to develop and investigate methods for point cloud generation by image matching using aerial image data collected by quadrocopter type micro unmanned aerial vehicle (UAV) imaging systems. Automatic generation of high-quality, dense point clouds from digital images by image matching is a recent, cutting-edge step forward in digital photogrammetric technology. The major components of the system for point cloud generation are a UAV imaging system, an image data collection process using high image overlaps, and post-processing with image orientation and point cloud generation. Two post-processing approaches were developed: one of the methods is based on Bae Systems’ SOCET SET classical commercial photogrammetric software and another is built using Microsoft®’s Photosynth™ service available in the Internet. Empirical testing was carried out in two test areas. Photosynth processing showed that it is possible to orient the images and generate point clouds fully automatically without any a priori orientation information or interactive work. The photogrammetric processing line provided dense and accurate point clouds that followed the theoretical principles of photogrammetry, but also some artifacts were detected. The point clouds from the Photosynth processing were sparser and noisier, which is to a large extent due to the fact that the method is not optimized for dense point cloud generation. Careful photogrammetric processing with self-calibration is required to achieve the highest accuracy. Our results demonstrate the high performance potential of the approach and that with rigorous processing it is possible to reach results that are consistent with theory. We also point out several further research topics. Based on theoretical and empirical results, we give recommendations for properties of imaging sensor, data collection and processing of UAV image data to ensure accurate point cloud generation.

Rosnell, Tomi; Honkavaara, Eija

2012-01-01

251

PSC Meteorology Program Cloud Boutique  

NSDL National Science Digital Library

Plymouth State College (PSC) provides the PSC Meteorology Program Cloud Boutique Website to "provide explanations of and access to detailed pictures of some basic cloud forms." Spectacular images and brief descriptions of high clouds (cirrus, cirrocumulus, and cirrostratus), middle clouds (altocumulus and altostratus), low clouds (cumulus, stratocumulus, stratus, and fog), multi-layer clouds (nimbostratus and cumulonimbus), and orographic clouds (lenticular and cap), among others are included. The site is an excellent general cloud reference.

252

The use of Space Shuttle images to improve cloud detection in mapping of tropical coral reef environments  

Microsoft Academic Search

Landsat and SPOT sensor data used for coral reef mapping were combined with multidate Space Shuttle photographs and digital video to distinguish small clouds from reef features. By using public-domain data from human spaceflights, we could use multidate techniques to improve mapping while reducing the number of satellite sensor images that had to be purchased. Results are illustrated for South

S. Andréfouët; J. A. Robinson

2003-01-01

253

Assessing the performance of the Lightning Imaging Sensor (LIS) using Deep Convective Clouds  

NASA Astrophysics Data System (ADS)

The stability of the LIS instrument is examined during a 13 year period (1998-2010) by examining LIS background radiance observations of Deep Convective Clouds (DCCs) which are identified by their cold IR brightness temperature. Pixels in the LIS background image associated with DCCs are identified and analyzed during July and August of each year in the 13 year period. The resulting LIS DCC radiances are found to be stable throughout the period, varying at most by 0.8% from the 13 year mean July August value of 358.1 W sr- 1 m- 2 ?m- 1. The DCC method in this study provides a good approach for evaluating the stability of the future GOES-R Geostationary Lightning Mapper (GLM).

Buechler, Dennis E.; Koshak, William J.; Christian, Hugh J.; Goodman, Steven J.

2014-01-01

254

Cloud Games  

NSDL National Science Digital Library

Play these two matching games from the Web Weather for Kids site to pair cloud images with their names/types! Developed by the University Corporation for Atmospheric Research, this site requires Java.

Programs, University C.

2010-01-01

255

Remote sensing of cloud, aerosol and water vapor properties from the Moderate Resolution Imaging Spectrometer (MODIS)  

NASA Technical Reports Server (NTRS)

The Moderate Resolution Imaging Spectrometer (MODIS) is an Earth-viewing sensor being developed as a facility instrument for the Earth Observing System (EOS) to be launched in the late 1990s. MODIS consists of two separate instruments that scan a swath width sufficient to provide nearly complete global coverage every two days from a polar-orbiting, Sun-synchronous, platform at an altitude of 705 km. Of primary interest for studies of atmospheric physics is the MODIS-N (nadir) instrument which will provide images in 36 spectral bands between 0.415 and 14.235 micrometers with spatial resoulutions of 250 m (2 bands), 500 m (5 bands) and 1000 m (29 bands). These bands have been carefully selected to enable advanced studies of land, ocean and atmosperhic processes. The intent of this lecture is to describe the current status of MODIS-N and its companion instrument MODIS-T (tilt), a tiltable cross-track scanning radiometer with 32 uniformly spaced channels between 0.410 and 0.875 micrometers, and to describe the physical principles behind the development of MODIS for the remote sensing of atmospheric properties. Primary emphasis will be placed on the main atmospheric applications of determining the optical, microphysical and physical properties of clouds and aerosol particles form spectral-reflection and thermal-emission measurements. In addition to cloud and aerosol properties, MODIS-N will be utilized for the determination of the total precipitable water vapor over land and atmospheric stability. The physical principles behind the determination of each of these atmospheric products will be described herein.

King, M. D.

1992-01-01

256

Saturn's cloud structure and temporal evolution from ten years of Hubble Space Telescope images (1994–2003)  

Microsoft Academic Search

We present a study of the vertical structure of clouds and hazes in the upper atmosphere of Saturn's Southern Hemisphere during 1994–2003, about one third of a Saturn year, based on Hubble Space Telescope images. The photometrically calibrated WFPC2 images cover the spectral region between the near-UV (218–255 nm) and the near-IR (953–1042 nm), including the 890 nm methane band.

S. Pérez-Hoyos; A. Sánchez-Lavega; R. G. French; J. F. Rojas

2005-01-01

257

Polarization of Directly Imaged Young Giant Planets as a Probe of Mass, Rotation, and Clouds  

NASA Technical Reports Server (NTRS)

Young, hot gas giant planets at large separations from their primaries have been directly imaged around several nearby stars. More such planets will likely be detected by ongoing and new imaging surveys with instruments such as the Gemini Planet Imager (GPI). Efforts continue to model the spectra of these planets in order to constrain their masses, effective temperatures, composition, and cloud structure. One potential tool for analyzing these objects, which has received relatively less attention, is polarization. Linear polarization of gas giant exoplanets can arise from the combined influences of light scattering by atmospheric dust and a rotationally distorted shape. The oblateness of gas giant planet increases of course with rotation rate and for fixed rotation also rises with decreasing gravity. Thus young, lower mass gas giant planets with youthful inflated radii could easily have oblateness greater than that of Saturn s 10%. We find that polarizations of over 1% may easily be produced in the near-infrared in such cases. This magnitude of polarization may be measurable by GPI and other instruments. Thus if detected, polarization of a young Jupiter places constraints on the combination of its gravity, rotation rate, and degree of cloudiness. We will present results of our multiple scattering analysis coupled with a self-consistent dusty atmospheric models to demonstrate the range of polarizations that might be expected from resolved exoplanets and the range of parameter space that such observations may inform.

Marley, Mark Scott; Sengupta, Sujan

2012-01-01

258

Characterizing growth patterns in longitudinal MRI using image contrast  

NASA Astrophysics Data System (ADS)

Understanding the growth patterns of the early brain is crucial to the study of neuro-development. In the early stages of brain growth, a rapid sequence of biophysical and chemical processes take place. A crucial component of these processes, known as myelination, consists of the formation of a myelin sheath around a nerve fiber, enabling the effective transmission of neural impulses. As the brain undergoes myelination, there is a subsequent change in the contrast between gray matter and white matter as observed in MR scans. In this work, gray-white matter contrast is proposed as an effective measure of appearance which is relatively invariant to location, scanner type, and scanning conditions. To validate this, contrast is computed over various cortical regions for an adult human phantom. MR (Magnetic Resonance) images of the phantom were repeatedly generated using different scanners, and at different locations. Contrast displays less variability over changing conditions of scan compared to intensity-based measures, demonstrating that it is less dependent than intensity on external factors. Additionally, contrast is used to analyze longitudinal MR scans of the early brain, belonging to healthy controls and Down's Syndrome (DS) patients. Kernel regression is used to model subject-specific trajectories of contrast changing with time. Trajectories of contrast changing with time, as well as time-based biomarkers extracted from contrast modeling, show large differences between groups. The preliminary applications of contrast based analysis indicate its future potential to reveal new information not covered by conventional volumetric or deformation-based analysis, particularly for distinguishing between normal and abnormal growth patterns.

Vardhan, Avantika; Prastawa, Marcel; Vachet, Clement; Piven, Joseph; Gerig, Guido

2014-03-01

259

Thermal neutron image intensifier tube provides brightly visible radiographic pattern  

NASA Technical Reports Server (NTRS)

Vacuum-type neutron image intensifier tube improves image detection in thermal neutron radiographic inspection. This system converts images to an electron image, and with electron acceleration and demagnification between the input target and output screen, produces a bright image viewed through a closed circuit television system.

Berger, H.; Kraska, I.; Niklas, W.; Schmidt, A.

1967-01-01

260

Image-based correlation of Laser Scanning point cloud time series for landslide monitoring  

NASA Astrophysics Data System (ADS)

Very high resolution monitoring of landslide kinematics is an important aspect for a physical understanding of the failure mechanisms and for quantifying the associated hazard. In the last decade, the potential of Terrestrial Laser Scanning (TLS) to monitor slow-moving landslides has been largely demonstrated but accurate processing methods are still needed to extract useful information available in point cloud time series. This work presents an approach to measure the 3D deformation and displacement patterns from repeated TLS surveys. The method is based on the simplification of a 3D matching problem in a 2D matching problem by using a 2D statistical normalized cross-correlation function. The computed displacement amplitudes are compared to displacements (1) calculated with the classical approach of Iterative Closest Point and (2) measured from repeated dGPS observations. The performance of the method is tested on a 3 years dataset acquired at the Super-Sauze landslide (South French Alps). The observed landslide displacements are heterogeneous in time and space. Within the landslide, sub-areas presenting different deformation patterns (extension, compression) are detected by a strain analysis. It is demonstrated that pore water pressure changes within the landslide is the main controlling factor of the kinematics.

Travelletti, Julien; Malet, Jean-Philippe; Delacourt, Christophe

2014-10-01

261

Local binary patterns for stromal area removal in histology images  

NASA Astrophysics Data System (ADS)

Nuclei counting in epithelial cells is an indication for tumor proliferation rate which is useful to rank tumors and select an appropriate treatment schedule for the patient. However, due to the high interand intra- observer variability in nuclei counting, pathologists seek a deterministic proliferation rate estimate. Histology tissue contains epithelial and stromal cells. However, nuclei counting is clinically restricted to epithelial cells because stromal cells do not become cancerous themselves since they remain genetically normal. Counting nuclei existing within the stromal tissue is one of the major causes of the proliferation rate non-deterministic estimation. Digitally removing stromal tissue will eliminate a major cause in pathologist counting variability and bring the clinical pathologist a major step closer toward a deterministic proliferation rate estimation. To that end, we propose a computer aided diagnosis (CAD) system for eliminating stromal cells from digital histology images based on the local binary patterns, entropy measurement, and statistical analysis. We validate our CAD system on a set of fifty Ki-67-stained histology images. Ki-67-stained histology images are among the clinically approved methods for proliferation rate estimation. To test our CAD system, we prove that the manual proliferation rate estimation performed by the expert pathologist does not change before and after stromal removal. Thus, stromal removal does not affect the expert pathologist estimation clinical decision. Hence, the successful elimination of the stromal area highly reduces the false positive nuclei which are the major confusing cause for the less experienced pathologists and thus accounts for the non-determinism in the proliferation rate estimation. Our experimental setting shows statistical insignificance (paired student t-test shows ? = 0.74) in the manual nuclei counting before and after our automated stromal removal. This means that the clinical decision of the expert pathologist is not affected by our CAD system which is what we want to prove. However, the usage of our CAD system substantially account for the reduced inter- and intra- proliferation rate estimation variability and especially for less-experienced pathologists.

Alomari, Raja S.; Ghosh, Subarna; Chaudhary, Vipin; Al-Kadi, Omar

2012-02-01

262

Visual simulation of clouds  

Microsoft Academic Search

Clouds present serious problems to standard computer image generation techniques because clouds do not have well-defined surfaces and boundaries. In addition, clouds contain varying degrees of translucence, and their amorphous structure can change with time. Although several approaches to cloud simulation have produced impressive results, they have relied on complex mathematical models which produce high computation costs for a single

Geoffrey Y. Gardner

1985-01-01

263

Wave Clouds off Korolev  

NASA Technical Reports Server (NTRS)

30 September 2004 This red wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a wavy cloud pattern formed in the lee of Korolev Crater, located near 72.8oN, 195.7oW. Korolev Crater is about 85 km (53 mi) in diameter and named for Sergei P. Korolev, a pioneering Russian rocket designer and engineer who died in the mid-1960s. The image, acquired in late northern summer, is illuminated by sunlight from the lower left.

2004-01-01

264

Analysis of spatio-temporal brain imaging patterns by hidden markov models and serial MRI images.  

PubMed

Brain changes due to development and maturation, normal aging, or degenerative disease are continuous, gradual, and variable across individuals. To quantify the individual progression of brain changes, we propose a spatio-temporal methodology based on Hidden Markov Models (HMM), and apply it on four-dimensional structural brain magnetic resonance imaging series of older individuals. First, regional brain features are extracted in order to reduce image dimensionality. This process is guided by the objective of the study or the specific imaging patterns whose progression is of interest, for example, the evaluation of Alzheimer-like patterns of brain change in normal individuals. These regional features are used in conjunction with HMMs, which aim to measure the dynamic association between brain structure changes and progressive stages of disease over time. A bagging framework is used to obtain models with good generalization capability, since in practice the number of serial scans is limited. An application of the proposed methodology was to detect individuals with the risk of developing MCI, and therefore it was tested on modeling the progression of brain atrophy patterns in older adults. With HMM models, the state-transition paths corresponding to longitudinal brain changes were constructed from two completely independent datasets, the Alzheimer Disease Neuroimaging Initiative and the Baltimore Longitudinal Study of Aging. The statistical analysis of HMM-state paths among the normal, progressive MCI, and MCI groups indicates that, HMM-state index 1 is likely to be a predictor of the conversion from cognitively normal to MCI, potentially many years before clinical symptoms become measurable. Hum Brain Mapp 35:4777-4794, 2014. © 2014 Wiley Periodicals, Inc. PMID:24706564

Wang, Ying; Resnick, Susan M; Davatzikos, Christos

2014-09-01

265

Three-dimensional transcranial ultrasound imaging of microbubble clouds using a sparse hemispherical array.  

PubMed

There is an increasing interest in bubble-mediated focused ultrasound (FUS) interventions in the brain. However, current technology lacks the ability to spatially monitor the interaction of the microbubbles with the applied acoustic field, something which is critical for safe clinical translation of these treatments. Passive acoustic mapping could offer a means for spatially monitoring microbubble emissions that relate to bubble activity and associated bioeffects. In this study, a hemispherical receiver array was integrated within an existing transcranial therapy array to create a device capable of both delivering therapy and monitoring the process via passive imaging of bubble clouds. A 128-element receiver array was constructed and characterized for varying bubble concentrations and source spacings. Initial in vivo feasibility testing was performed. The system was found to be capable of monitoring bubble emissions down to single bubble events through an ex vivo human skull. The lateral resolution of the system was found to be between 1.25 and 2 mm and the axial resolution between 2 and 3.5 mm, comparable to the resolution of MRI-based temperature monitoring during thermal FUS treatments in the brain. The results of initial in vivo experiments show that bubble activity can be mapped starting at pressure levels below the threshold for blood-brain barrier disruption. This study presents a feasible solution for imaging bubble activity during cavitation-mediated FUS treatments in the brain. PMID:24658252

O'Reilly, Meaghan A; Jones, Ryan M; Hynynen, Kullervo

2014-04-01

266

Temporal variations of zonal wind speed at Venus cloud tops from Venus Monitoring Camera UV images  

NASA Astrophysics Data System (ADS)

Venus Monitoring Camera (VMC) [1] on board the Venus Express mission obtained great number of UV images of the upper cloud. The observations cover about 10 Venusian years. 600 orbits or about 25% of all available UV images were processed by the digital wind tracking routine resulting in ~400000 vectors for the whole period of observations. Mean profiles were calculated for individual orbits. Time series of zonal speed for 5 degrees latitude bins centered at 10, 15, 20, 25 and 30 South were created from the individual mean profiles. The time series were investigated for periodicities by using Deeming algorithm [2] for unequally-spaced data. Two groups of the periods were found. The first group is close to the period of superrotation at low latitudes (4.83±0.1 days) with the period 4.1-5.1 days and the amplitude ranging from ±4.26 to ±17.44 m/s. The amplitude and phase of oscillations demonstrates dependence from the latitude and also time variability with preserving stable parameters of oscillation during at least 70 days. The second one is a long term periods caused by orbital motion of Venus (116 days, 224 days) and is related to the periodicity in the VMC observations.

Khatuntsev, I. V.; Patsaeva, M. V.; Ignatiev, N. I.; Titov, D. V.; Markiewicz, W. J.; Turin, A. V.

2012-09-01

267

ENVI Services Engine: Earth and Planetary Image Processing for the Cloud  

NASA Astrophysics Data System (ADS)

The geospatial imagery analysis and exploitation community has a growing need for online analytic capabilities. Work previously done on desktop workstations must migrate to a web-accessible environment to mitigate growing data volumetrics, bandwidth usage, and end user requirements. Web based applications (or 'apps') are intended to apply analytic methods, procedures, and routines to image datasets stored within centralized server repositories. Exelis Visual information Solutions (VIS) developed an enterprise-enabled processing engine that provides remote users access to the power of ENVI image analysis and IDL applications from a web or mobile client interface. The working name for this capability is the ENVI and IDL Services Engine (ESE). This engine now enables the remote user to gain access to the same compiled ENVI and IDL functions and procedures that remote sensing scientists have utilized for decades at the desktop level. ESE operates in a RESTful state, listening for http calls to arrive that initiate a data processing operation once those messages are registered. ESE is middleware agnostic, meaning users can implement this capability using their current enterprise architecture such as ArcGIS Server or GeoServer. Flexibility and openness in middleware components is achieved through the use of OGC standards for message and data transfer. ESE represents bringing long term earth science monitoring analysis capabilities to the cloud, harnessing existing ENVI and IDL tools and deploying them to the enterprise, and improving access to earth and planetary science data.

O'Connor, A. S.; Lausten, K.; Heightley, K.; Harris, T.

2012-12-01

268

Speckle reduction in THz imaging systems with multiple phase patterns  

Microsoft Academic Search

THz technology makes possible imaging of phenomena, inaccessible to both visible and infrared radiation, but the imaging is still in its early stages of development. This paper draws attention to the aspects of speckle reduction to improve the image quality. Because all existing THz sources are coherent - speckle is an ultimate limiting factor of the free-space imaging techniques. Speckle

Irina Jaeger; Johan Stiens; Gaetan Koers; Gert Poesen; Roger Vounckx

2006-01-01

269

The Seasonal and Diurnal Patterns of net Ecosystem CO2 Exchange in a Subtropical Montane Cloud Forest.  

NASA Astrophysics Data System (ADS)

CO2 fluxes were measured by an open/closed path eddy covariance system at a natural regenerated 50-years-old yellow cypress (Chamaecyparis obtusa var. formosana) forest at Chi-Lan Mountain site (CLM site, 24°35'N, 121°25'E, 1650 m elevation), north-eastern Taiwan. CLM site is located at a relative uniform south-eastern-facing valley slope (15°) characterized with year round fog occurrence and diurnal mountain-valley wind and can be classified as subtropical montane cloud forest. Based on measurement from July 2007 to June 2008, seasonal and diurnal patterns of CO2 fluxes were described and patterns under different cloudiness and foggy conditions were presented. Comparing with other cypress forests in temperate region, there is only a weak seasonal pattern of the CO2 fluxes at CLM site. Throughout the year, average incident photosynthetically active radiation in summer was almost the double of that in winter, whereas the difference of mean daytime CO2 fluxes among seasons was much less than the seasonal light difference. During summer when light intensity was higher, mean daytime CO2 fluxes reached -7.5 ?mol/m2/s in July and -8.8 ?mol/m2/s in August. As heavy fog accounted for 64% and 67% of the time in November and February, mean daytime CO2 fluxes dropped to -6.9 and -6.1 ?mol/m2/s respectively. With comparable higher incident radiation intensity (>1000 ?mol/m2/s), the CO2 fluxes were higher in overcast days than in clear days. In July 2007, clear days accounted for 30% of the month, light intensity reached its peak at midday, and however, CO2 fluxes didn't reach its highest value in the meanwhile. Canopy conductance calculated from the Penman-Monteith equation and measured latent heat fluxes both showed a midday depression at clear days, which indicated the regulation of transpiration by plant physiological mechanism. With comparable lower incident radiation intensity (<1000 ?mol/m2/s), the CO2 fluxes were higher in overcast days than in foggy days. The difference suggested that water droplets deposited on leaves might partially block the pathway of the gas exchange through stomata as canopy immersed in the very humid air. However, CO2 fluxes did not cease during foggy periods, as also supported by sap flow and leaf chamber measurements, the morphological characteristics of leaf or/and canopy structure might contribute to the well adaptability of this subtropical montane cloud forest to the humid environment.

Chu, H.; Lai, C.; Wu, C.; Hsia, Y.

2008-12-01

270

Visibility-reducing species in the denver "brown cloud"—II. Sources and temporal patterns  

NASA Astrophysics Data System (ADS)

The chemical and optical measurements collected at the General Motors Research Laboratories' site during the 1978 Denver "brown cloud" study are combined with data on energy consumption and emissions, as well as the use of tracer techniques, to estimate the contributions of the various sources to the fine paniculate mass (FPM) and the visual range reduction (VRR). Although no single source dominates either the FPM or the VRR, combustion processes account for over 80% of both. The major contributors to both the FPM and VRR are: motor vehicles, 26 and 27% (diesel trucks, 8 and 12%; light-duty noncatalyst vehicles. 14 and 9%; light-duty catalyst-equipped vehicles, 4 and 5% and tire rubber, negligible and 1%), coal combustion, > 20 and > 25%, and wood burning, 12 and 18%. The remainders of the FPM and VRR are due chiefly to fuel oil and natural-gas combustion and crustal and fly ash material. The motor vehicles and the wood combustion are the principal sources of both elemental and organic carbon particles while the coal combustion is the most important source of paniculate sulfate and nitrate precursors. Essentially, all the carbonaceous particles appear to be primary particles while most of the sulfate appears to be produced by a heterogeneous process. Both heterogeneous and homogeneous (photochemical) mechanisms appear to be producing nitrate, with the photochemical one being more important.

Wolff, G. T.; Countess, R. J.; Groblicki, P. J.; Ferman, M. A.; Cadle, S. H.; Muhlbaier, J. L.

271

Cloud denoising  

NASA Astrophysics Data System (ADS)

We address the issue of cloud removal from images. Typically a cloud on an image is not uniform and we develop methods that do denoising on a local level. In this paper we present preliminary studies of such methods and also a method for image fusion. The procedure is based on the use of a denoising pixel-level measure. The measure is defined through a 1-D Pseudo Wigner Distribution (PWD) applied to non-overlapping N-pixel window slices of the original image. The method is illustrated with different set of artificial and natural cloudy or foggy images, which are partially occluded by clouds in different regions. Another advantage of the present approach is its reduced computational cost in comparison with other methods based on a full 2-D implementation of the PWD.

Gabarda, Salvador; Cristobal, Gabriel; Galleani, Lorenzo; Cohen, Leon

2004-05-01

272

Adaptive fringe-pattern projection for image saturation avoidance in 3D surface-shape measurement.  

PubMed

In fringe-projection 3D surface-shape measurement, image saturation results in incorrect intensities in captured images of fringe patterns, leading to phase and measurement errors. An adaptive fringe-pattern projection (AFPP) method was developed to adapt the maximum input gray level in projected fringe patterns to the local reflectivity of an object surface being measured. The AFPP method demonstrated improved 3D measurement accuracy by avoiding image saturation in highly-reflective surface regions while maintaining high intensity modulation across the entire surface. The AFPP method can avoid image saturation and handle varying surface reflectivity, using only two prior rounds of fringe-pattern projection and image capture to generate the adapted fringe patterns. PMID:24787871

Li, Dong; Kofman, Jonathan

2014-04-21

273

Coherent lidar imaging of dust clouds: waveform comparison with the poly-phase (P4) modulation waveform  

NASA Astrophysics Data System (ADS)

A dust or aerosol cloud represents a convenient target to examine the capabilities of range-resolved Doppler and intensity (RRDI) or inverse synthetic aperture ladar (ISAR) imaging coherent laser radar, known as coherent "lidar" for optically thin targets. The poly-phase P4 ladar waveform and its RRDI images are described and compared with previous pulse-burst, linear-FM chirp pulse-compression, pseudo-random phase modulation waveforms, and several other waveforms which have not been utilized to date. A "dust cloud" has very many independently moving point scatterers with velocities that are approximately Gaussian randomly distributed in x,y,z with standard deviations of about 10% of the mean wind + aerosol velocity. This is contrary to a hard-target where the point scatterers are rigidly attached and moving together. The dust cloud produced speckle effects for the various ladar waveforms are compared. In addition, a reference set of four corner-cube retro-reflectors within the dust cloud further illustrates the differences in the various waveform capabilities and resolution.

Youmans, Douglas G.

2008-05-01

274

Digital image processing: effect on detectability of simulated low-contrast radiographic patterns  

Microsoft Academic Search

Detection studies of simulated low-contrast radiographic patterns were performed with a high-quality digital image processing system. The original images, prepared with conventional screen-film systems, were processed digitally to enhance contrast by a ''windowing'' technique. The detectability of simulated patterns was quantified in terms of the results of observer performance experiments by using the multiple-alternative forced-choice method. The processed images demonstrated

M. Ishida; K. Doi; L. N. Loo; C. E. Metz; J. L. Lehr

1984-01-01

275

CERES CLoud Effects  

NSDL National Science Digital Library

This computer-generated animation depicts the Clouds and the Earth's Radiant Energy System (CERES) instrument in operation. CERES measures the energy at the top of the atmosphere and estimates energy levels in the atmosphere and at the Earth's surface. Using information from very high resolution cloud-imaging instruments on the same spacecraft, CERES also will determine cloud properties, including cloud amount, altitude, thickness, and the size of the cloud particles.

1997-06-06

276

Deep Imaging Surveys of Star-forming Clouds. I. New Herbig-Haro Flows in NGC 2264  

NASA Astrophysics Data System (ADS)

We have embarked on a major, imaging survey of nearby star-forming regions using wide-field imaging detectors to identify and characterize the full population of Herbig-Haro flows from newborn stars in each region. In this study we present our survey results for the NGC 2264 region in Monoceros, where we have found a number of new Herbig-Haro objects, HH 571-HH 585, including several giant, parsec-scale flows. We discuss the individual flows and attempt to locate their region of origin. In particular, we identify two quadrupolar HH flows emanating from two cloud cores and associated with major molecular outflows. We also draw attention to what appears to be a region of major blowout of gas from a cloud core rich in young stars.

Reipurth, Bo; Yu, Ka Chun; Moriarty-Schieven, Gerald; Bally, John; Aspin, Colin; Heathcote, Steve

2004-02-01

277

Direct imaging of the extremely large host galaxy and gas cloud surrounding the quasar 3C275.1  

NASA Technical Reports Server (NTRS)

Direct CCD images of the field of the quasar 3C275.1 have been obtained using v, r, and redshifted forbidden O II filters to study the ionized gas cloud surrounding the quasar and to determine the gross characteristics of the quasar host galaxy. The images show an elliptical substrate containing several bright knots and indicate that the host galaxy is extremely large and luminous. The host galaxy's luminosity, dimensions, and position at the cluster center suggest that it may be a cD or 'proto-cD'. The nebulosity may be accreting matter from a 'cooling flow' of the intracluster medium. Alternatively, the quasar and the surrounding galaxy and gas cloud may be the result of repeated galaxy collisions.

Hintzen, Paul; Romanishin, W.

1986-01-01

278

Multi-Scale Fractal Analysis of Image Texture and Pattern  

NASA Technical Reports Server (NTRS)

Analyses of the fractal dimension of Normalized Difference Vegetation Index (NDVI) images of homogeneous land covers near Huntsville, Alabama revealed that the fractal dimension of an image of an agricultural land cover indicates greater complexity as pixel size increases, a forested land cover gradually grows smoother, and an urban image remains roughly self-similar over the range of pixel sizes analyzed (10 to 80 meters). A similar analysis of Landsat Thematic Mapper images of the East Humboldt Range in Nevada taken four months apart show a more complex relation between pixel size and fractal dimension. The major visible difference between the spring and late summer NDVI images of the absence of high elevation snow cover in the summer image. This change significantly alters the relation between fractal dimension and pixel size. The slope of the fractal dimensional-resolution relation provides indications of how image classification or feature identification will be affected by changes in sensor spatial resolution.

Emerson, Charles W.; Lam, Nina Siu-Ngan; Quattrochi, Dale A.

1999-01-01

279

Multi-Scale Fractal Analysis of Image Texture and Pattern  

NASA Technical Reports Server (NTRS)

Analyses of the fractal dimension of Normalized Difference Vegetation Index (NDVI) images of homogeneous land covers near Huntsville, Alabama revealed that the fractal dimension of an image of an agricultural land cover indicates greater complexity as pixel size increases, a forested land cover gradually grows smoother, and an urban image remains roughly self-similar over the range of pixel sizes analyzed (10 to 80 meters). A similar analysis of Landsat Thematic Mapper images of the East Humboldt Range in Nevada taken four months apart show a more complex relation between pixel size and fractal dimension. The major visible difference between the spring and late summer NDVI images is the absence of high elevation snow cover in the summer image. This change significantly alters the relation between fractal dimension and pixel size. The slope of the fractal dimension-resolution relation provides indications of how image classification or feature identification will be affected by changes in sensor spatial resolution.

Emerson, Charles W.; Lam, Nina Siu-Ngan; Quattrochi, Dale A.

1999-01-01

280

Tropical Rainfall Measuring Mission microwave imaging capabilities for the observation of rain clouds  

NASA Astrophysics Data System (ADS)

Brightness temperature simulations were used to assess the information loss due to the coarse spatial sampling of the Tropical Rainfall Measuring Mission (TRMM) microwave imager (TMI). While the high-resolution simulation of a three-dimensional rain cloud clearly identifies the 10.7-GHz channel to be superior for surface rainfall measurements, its comparably poor spatial resolution reduces the dynamic range of observable brightness temperatures and associated area-averaged rain rates considerably. This problem can be partly overcome by applying deconvolution techniques as demonstrated by Robinson et al. [1992]. When the sensitivity of resolution enhancement to noise amplification is investigated, an optimum configuration of key parameters was identified. Using an 11×11 matrix of neighboring pixels and noise reduction parameter of ? = 0.5° provides a 42×26 km resolution, compared with the original resolution of 63×38 km. Thus a noise amplification by a factor of 3 is introduced. Although this method does not match the resolution of the 19.35-GHz channel, the dynamic range of brightness temperatures and area-averaged rain rates could be increased by a factor of 2.7 and 2.2, respectively. Further resolution enhancement leads to noise levels which seem unacceptable with respect to the retrieval of geophysical parameters.

Bauer, P.; Bennartz, R.

1998-03-01

281

The Large Magellanic Cloud: A Power Spectral Analysis of Spitzer Images  

NASA Astrophysics Data System (ADS)

We present a power spectral analysis of Spitzer images of the Large Magellanic Cloud.The power spectra of the FIR emission show two different power laws.At larger scales (kpc) the slope is ~ -1.6, while at smaller ones (tens to few hundreds of parsecs) the slope is steeper, with avalue ~ -2.9.The break occurs at a scale ~ 100 - 200 pc. We interpret this break as the scale height of the dust disk of the LMC. We perform high-resolution simulations with and without stellar feedback.Our AMR hydrodynamic simulations of model galaxies using the LMC mass and rotation curve confirm that they have similar two-component power laws for projected density - and that the break does indeed occur at the disk thickness. Power spectral analysis of velocities betrays a single power law for in-plane components.The vertical component of the velocity shows a flat behavior for large structures and a power law similar to the in-plane velocities at small scales. The motions are highly anisotropic at large scales,with in-plane velocities being much more important than vertical ones.In contrast, at small scales, the motions become more isotropic.

Puerari, Ivânio; Block, David L.; Elmegreen, Bruce G.; Bournaud, Frédéric

282

Cloud-to-ground lightning and upper-air patterns during bursts and breaks in the southwest monsoon  

SciTech Connect

Convective bursts and breaks in the southwest U.S. monsoon are investigated in a lightning context because cloud-to-ground (CG) lightning is an excellent indicator of deep convection. Bursts and breaks are identified using six years of Bureau of Land Management CG lightning information. Composited upper-air analyses for 12 bursts and 10 breaks are developed to examine the synoptic-scale differences between these two regimes. Anomaly patterns are investigated, and average burst and break regimes are presented. This investigation shows the importance of moisture, the location of the subtropical ridge axis, and the high-plateau thermal low. For the burst, the ridge axis is displaced northward across Arizona and New Mexico and moisture is usually abundant in the southwestern United States. During the break, the ridge retreats southward into northern Mexico, giving way to dry westerly winds across Arizona. The high-plateau thermal low is firmly in place during July and August, and it pulls-low-level moist air upslope into the Great Basin from the Gulf of California through the only opening available, which is the lower desert of Arizona.

Watson, A.I.; Holle, R.L.; Lopez, R.E. [NOAA, Norman, OK (United States)] [NOAA, Norman, OK (United States)

1994-08-01

283

Basic research planning in mathematical pattern recognition and image analysis  

NASA Technical Reports Server (NTRS)

Fundamental problems encountered while attempting to develop automated techniques for applications of remote sensing are discussed under the following categories: (1) geometric and radiometric preprocessing; (2) spatial, spectral, temporal, syntactic, and ancillary digital image representation; (3) image partitioning, proportion estimation, and error models in object scene interference; (4) parallel processing and image data structures; and (5) continuing studies in polarization; computer architectures and parallel processing; and the applicability of "expert systems" to interactive analysis.

Bryant, J.; Guseman, L. F., Jr.

1981-01-01

284

Mobile cloud computing educational tool for image\\/video processing algorithms  

Microsoft Academic Search

This paper shows the importance and benefit of coupling cloud computing with mobile especially due to power limitations that mobile devices exhibit. Moreover, the work done shows that mobile computing can be applied for educational purposes, where a tool for students termed Mobi4Ed is presented. This educational tool aims at exploiting the concept of cloud computing in the context of

Rony Ferzli; Ibrahim Khalife

2011-01-01

285

RIM-13: A high-resolution imaging tool for aerial image monitoring of patterned and blank EUV reticles  

NASA Astrophysics Data System (ADS)

Key features of the RIM-13 EUV actinic reticle imaging microscope are summarised. This is a tool which generates aerial images from blank or patterned EUV masks, emulating the illumination and projection optics of an exposure tool. Such images of mask defects, acquired by a CCD camera, are analysed using the tool software to predict their effect on resist exposure. Optical, mechanical and software performance of the tool are reported.

Booth, M.; Brunton, A.; Cashmore, J.; Elbourn, P.; Elliner, G.; Gower, M.; Greuters, J.; Hirsch, J.; Kling, L.; McEntee, N.; Richards, P.; Truffert, V.; Wallhead, I.; Whitfield, M.

2006-04-01

286

Task-specific deactivation patterns in functional magnetic resonance imaging  

Microsoft Academic Search

In general, image analysis of cognitive experiments using functional magnetic resonance imaging techniques has emphasized those regions of the brain where increases in signal intensity, with regard to the reference state, are associated with activation. Nevertheless, a number of recent papers have shown that there are areas of deactivation as well. In this study, we have used a univariate analysis

M Hutchinson; W Schiffer; S Joseffer; A Liu; R Schlosser; S Dikshit; E Goldberg; J. D Brodie

1999-01-01

287

Statistical image recovery from laser speckle patterns with polarization diversity  

NASA Astrophysics Data System (ADS)

This research extends the theory and understanding of the laser speckle imaging technique. This non-traditional imaging technique may be employed to improve space situational awareness and image deep space objects from a ground-based sensor system. The use of this technique is motivated by the ability to overcome aperture size limitations and the distortion effects from Earth's atmosphere. Laser speckle imaging is a lensless, coherent method for forming two-dimensional images from their autocorrelation functions. Phase retrieval from autocorrelation data is an ill-posed problem where multiple solutions exist. This research introduces polarization diversity as a method for obtaining additional information so the structure of the object being reconstructed can be improved. Results show that in some cases the images restored using polarization diversity are superior to those reconstructed without it. This research presents statistical analysis of the observed data, two distinct image recovery algorithms, and a Cramer-Rao Lower Bound on resolution. A mathematical proof is provided to demonstrate the statistical properties of the observed, noisy autocorrelation data. The algorithms are constructed using the Expectation-Maximization approach and a polarization parameter that relates two independently observed data channels. The algorithms are validated with computer simulation and laboratory experiment. Comparison is made to an existing phase-retrieval technique. The theoretical lower bound is developed for comparing theoretical performance with and without polarization diversity. The results demonstrate the laser speckle imaging technique is improved with polarization diversity.

Dixon, Donald B.

288

Cloud Screening and Quality Control Algorithm for Star Photometer Data: Assessment with Lidar Measurements and with All-sky Images  

NASA Technical Reports Server (NTRS)

This paper presents the development and set up of a cloud screening and data quality control algorithm for a star photometer based on CCD camera as detector. These algorithms are necessary for passive remote sensing techniques to retrieve the columnar aerosol optical depth, delta Ae(lambda), and precipitable water vapor content, W, at nighttime. This cloud screening procedure consists of calculating moving averages of delta Ae() and W under different time-windows combined with a procedure for detecting outliers. Additionally, to avoid undesirable Ae(lambda) and W fluctuations caused by the atmospheric turbulence, the data are averaged on 30 min. The algorithm is applied to the star photometer deployed in the city of Granada (37.16 N, 3.60 W, 680 ma.s.l.; South-East of Spain) for the measurements acquired between March 2007 and September 2009. The algorithm is evaluated with correlative measurements registered by a lidar system and also with all-sky images obtained at the sunset and sunrise of the previous and following days. Promising results are obtained detecting cloud-affected data. Additionally, the cloud screening algorithm has been evaluated under different aerosol conditions including Saharan dust intrusion, biomass burning and pollution events.

Ramirez, Daniel Perez; Lyamani, H.; Olmo, F. J.; Whiteman, D. N.; Navas-Guzman, F.; Alados-Arboledas, L.

2012-01-01

289

Remote sensing of cloud droplet size distributions in DC3 with the UMBC-LACO Rainbow Polarimetric Imager (RPI)  

NASA Astrophysics Data System (ADS)

The UMBC Rainbow Polarimetric Imager is a small form factor VIS imaging polarimeter suitable for use on a number of platforms. An optical system based on a Phillips prism with three Bayer filter color detectors, each detecting a separate polarization state, allows simultaneous detection of polarization and spectral information. A Mueller matrix-like calibration scheme corrects for polarization artifacts in the optical train and allows retrieval of the polarization state of incoming light to better than 0.5%. Coupled with wide field of view optics (~90°), RPI can capture images of cloudbows over a wide range of aircraft headings and solar zenith angles for retrieval of cloud droplet size distribution (DSD) parameters. In May-June 2012, RPI was flown in a nadir port on the NASA DC-8 during the DC3 field campaign. We will show examples of cloudbow DSD parameter retrievals from the campaign to demonstrate the efficacy of such a system to terrestrial atmospheric remote sensing. RPI image from DC3 06/15/2012 flight. Left panel is raw image from the RPI 90° camera. Middle panel is Stokes 'q' parameter retrieved from full three camera dataset. Right panel is a horizontal cut in 'q' through the glory. Both middle and right panels clearly show cloudbow features which can be fit to infer cloud DSD parameters.

Buczkowski, S.; Martins, J.; Fernandez-Borda, R.; Cieslak, D.; Hall, J.

2013-12-01

290

Milliarcsecond imaging of clumpy dust clouds in the red giant L2 Pup with the Very Large Telescope Interferometer  

NASA Astrophysics Data System (ADS)

Despite its importance in mass loss, the dust formation in AGB stars is not yet understood well. There is growing evidence that the dust envelopes of AGB stars are much more complex--clumpy and/or bipolar--than spherically expanding shells. The non-spherical structures emerging in AGB stars may be the seed of asymmetry in planetary nebulae. However, direct observations of the clumpy dust cloud formation close to the star is difficult, because we need milliarcsecond spatial resolution. We present milliarcsecond resolution near-IR imaging of the bright, nearby M giant L2 Pup. The 2.2 micron image taken with VLT/NACO at a spatial resolution of 54 mas shows an asymmetric circumstellar envelope with 300 x 200 mas (12 x 8 stellar radii), elongated in East-West direction. Furthermore, we succeeded in aperture-synthesis imaging of L2 Pup by combining these single-dish VLT/NACO data with near-IR interferometric data taken with the AMBER instrument at the Very Large Telescope Interferometer. The reconstructed image with a spatial resolution of 12 mas shows two clumps at 20--30 mas away from the star, as well as another clump over the stellar. This is the first imaging of clumpy dust clouds toward L2 Pup, whose presence was only inferred from polarimetric and photometric observations. Our observations reveal the clumpy dust formation close to the star, at 1.5--2.5 stellar radii.

Ohnaka, K.; Schertl, D.; Hofmann, K. H.; Weigelt, G.

2014-04-01

291

Preliminary global cloud comparisons from the AVHRR, MODIS, and GLAS: cloud amount and cloud overlap  

Microsoft Academic Search

Near-global total cloud frequencies and multilayered cloud frequencies derived from AVHRR (Advanced Very High Resolution Radiometer), MODIS (Moderate Resolution Imaging Spectroradiometer), and GLAS (Geoscience Laser Altimeter System) were analyzed and compared. The GLAS retrievals can be used to quantify the amount of cloud that may go undetected from satellite imagers such AVHRR and MODIS and to help validate satellite cloud

Michael J. Pavolonis; Andrew K. Heidinger

2005-01-01

292

Multispectral cloud-clearing using IASI sounding and collocated AVHRR imager measurements  

NASA Astrophysics Data System (ADS)

E. S. Maddy2, T. S. King2, H. Sun2, W. W. Wolf1, C. D. Barnet1, A. Heidinger1,Z. Cheng2, and A. Gambacorta2 1NOAA/NESDIS/Center for Satellite Applications and Research, Camp Springs, Maryland, USA 2Dell, Fairfax, Virginia, USA There are several approaches for handling the effect of clouds in the IR, the most common of which include: avoiding the clouds by screening for clear-sky footprints; directly modeling the radiative effect of the clouds using sophisticated radiative transfer and cloud microphysical models; and, estimating the clear-sky portion of an IR scene by using a number of adjacent and variably cloudy footprints coupled with an estimate of the clear-sky radiance from a forecast model or collocated satellite instrument less likely to be affected by clouds. The last approach, termed cloud-clearing, is currently used at NOAA/NESDIS for operational IASI processing. NOAA currently operationally processes 100% of IASI data from calibrated and apodized L1C spectral measurements to geophysical L2 products and distributes these products to the NOAA/Comprehensive Large Array-data Stewardship System (CLASS) (available at http://class.ngdc.noaa.gov). The current algorithm used to produce the L2 products from IASI is largely based on the AIRS science team (AST) algorithm including the fast Radiative Transfer Algorithm (RTA), fast eigenvector regression, as well as cloud-clearing and physical retrieval methodologies which rely on microwave measurements from collocated AMSU to handle the effects of clouds in the IR. We will describe future upgrades to the operational cloud-clearing algorithm being used for IASI processing within NOAA/NESDIS. Specifically, our new cloud-clearing algorithm leverages off of the MetOp-A AVHRR Clouds from AVHRR (CLAVR-x) cloud mask to provide high quality, high spatial resolution InfraRed (IR) window clear-sky scene radiance estimates required for cloud-clearing inputs and quality assurance. The direct use of AVHRR clear-sky measurements decreases limitations of the current algorithm to provide high quality clear-sky radiance estimates throughout the atmospheric column, and especially near the surface to a high degree of accuracy. In turn, this enables the IASI sounder to provide high quality and high vertical and spatial resolution soundings temperature and trace gases for the study of weather and climate processes.

Maddy, E. S.; King, T. S.; Sun, H.; Wolf, W.; Barnet, C.; Heidinger, A. K.; Cheng, Z.; Gambacorta, A.

2010-12-01

293

Cloud Computing for radiologists.  

PubMed

Cloud computing is a concept wherein a computer grid is created using the Internet with the sole purpose of utilizing shared resources such as computer software, hardware, on a pay-per-use model. Using Cloud computing, radiology users can efficiently manage multimodality imaging units by using the latest software and hardware without paying huge upfront costs. Cloud computing systems usually work on public, private, hybrid, or community models. Using the various components of a Cloud, such as applications, client, infrastructure, storage, services, and processing power, Cloud computing can help imaging units rapidly scale and descale operations and avoid huge spending on maintenance of costly applications and storage. Cloud computing allows flexibility in imaging. It sets free radiology from the confines of a hospital and creates a virtual mobile office. The downsides to Cloud computing involve security and privacy issues which need to be addressed to ensure the success of Cloud computing in the future. PMID:23599560

Kharat, Amit T; Safvi, Amjad; Thind, Ss; Singh, Amarjit

2012-07-01

294

Evaluation of Satellite Image Lineament Patterns in Raume Baden-Frick-Laufenburg-Zurzach.  

National Technical Information Service (NTIS)

Satellite images often show a dense network of linear elements. The effective meaning of these lineament patterns is still under discussion, especially as to their significance in structural interpretations. In northern Switzerland, a detailed comparison ...

A. Isler

1984-01-01

295

Proceedings of the NASA Symposium on Mathematical Pattern Recognition and Image Analysis  

NASA Technical Reports Server (NTRS)

The application of mathematical and statistical analyses techniques to imagery obtained by remote sensors is described by Principal Investigators. Scene-to-map registration, geometric rectification, and image matching are among the pattern recognition aspects discussed.

Guseman, L. F., Jr.

1983-01-01

296

Integrated spatio-spectral method for efficiently suppressing honeycomb pattern artifact in imaging fiber bundle microscopy  

NASA Astrophysics Data System (ADS)

In a fiber bundle, spots of varying intensity occur throughout the fiber structure, and the ensemble of these spots creates the honeycomb pattern image, called a pixelated image. The spatio-spectral method, an integrated suppression method for the honeycomb pattern in the spatial and Fourier (spectral) domains, has demonstrated efficient restoration of microscopic images based on the fiber bundle. The morphological processing in the spatial domain partially interpolated the gaps between the circular patterns of fiber cores, and the selective band-reject filter in the Fourier domain was applied to reduce the honeycomb-shaped artifact. The auto-corrective search for the global peaks in the localized region was employed to apply the notch filter to the exact position of the individual periodic component in the Fourier domain. We found that a closing preprocessing in the spatial domain, combined with a Gaussian notch Fourier domain filter, yields the optimum image quality when eliminating the honeycomb pattern.

Lee, Cheon-Yang; Han, Jae-Ho

2013-10-01

297

Patterned Resonance Plasmonic Microarrays for High-Performance SPR Imaging  

PubMed Central

We report a novel optical platform based on SPR generation and confinement inside a defined 3-dimensional microwell geometry that leads to background resonance-free SPR images. The array shows an exceptionally high signal-to-noise ratio (S/N>80) for imaging analysis and subnanometric thickness resolution. An angular sensitivity of 1 degree/0.01 RIU has been achieved and the signal to background ratio (S/B) improves to 20, one order of magnitude higher than best literature results. The design proves effective for probing supported lipid membrane arrays in real time with a thickness resolution of 0.24 nm and allows for imaging analysis of microfluidic circuits where resonant spots are separated by only one pixel (~ 7 ?m). The high image quality and unique chip geometry open up new avenues for array screening and biomicrofluidics using SPRi detection.

Abbas, Abdennour; Linman, Matthew J.; Cheng, Quan

2011-01-01

298

Multi-Scale Fractal Analysis of Image Texture and Pattern  

NASA Technical Reports Server (NTRS)

Fractals embody important ideas of self-similarity, in which the spatial behavior or appearance of a system is largely scale-independent. Self-similarity is a property of curves or surfaces where each part is indistinguishable from the whole. The fractal dimension D of remote sensing data yields quantitative insight on the spatial complexity and information content contained within these data. Analyses of Normalized Difference Vegetation Index (NDVI) images of homogeneous land covers near Huntsville, Alabama revealed that the fractal dimension of an image of an agricultural land cover indicates greater complexity as pixel size increases, a forested land cover gradually grows smoother, and an urban image remains roughly self-similar over the range of pixel sizes analyzed(l0 to 80 meters). The forested scene behaves as one would expect-larger pixel sizes decrease the complexity of the image as individual clumps of trees are averaged into larger blocks. The increased complexity of the agricultural image with increasing pixel size results from the loss of homogeneous groups of pixels in the large fields to mixed pixels composed of varying combinations of NDVI values that correspond to roads and vegetation. The same process occur's in the urban image to some extent, but the lack of large, homogeneous areas in the high resolution NDVI image means the initially high D value is maintained as pixel size increases. The slope of the fractal dimension-resolution relationship provides indications of how image classification or feature identification will be affected by changes in sensor resolution.

Emerson, Charles W.; Quattrochi, Dale A.; Luvall, Jeffrey C.

1997-01-01

299

A comparison of performance of automatic cloud coverage assessment algorithm for Formosat-2 image using clustering-based and spatial thresholding methods  

NASA Astrophysics Data System (ADS)

Formosat-2 image is a kind of high-spatial-resolution (2 meters GSD) remote sensing satellite data, which includes one panchromatic band and four multispectral bands (Blue, Green, Red, near-infrared). An essential sector in the daily processing of received Formosat-2 image is to estimate the cloud statistic of image using Automatic Cloud Coverage Assessment (ACCA) algorithm. The information of cloud statistic of image is subsequently recorded as an important metadata for image product catalog. In this paper, we propose an ACCA method with two consecutive stages: preprocessing and post-processing analysis. For pre-processing analysis, the un-supervised K-means classification, Sobel's method, thresholding method, non-cloudy pixels reexamination, and cross-band filter method are implemented in sequence for cloud statistic determination. For post-processing analysis, Box-Counting fractal method is implemented. In other words, the cloud statistic is firstly determined via pre-processing analysis, the correctness of cloud statistic of image of different spectral band is eventually cross-examined qualitatively and quantitatively via post-processing analysis. The selection of an appropriate thresholding method is very critical to the result of ACCA method. Therefore, in this work, We firstly conduct a series of experiments of the clustering-based and spatial thresholding methods that include Otsu's, Local Entropy(LE), Joint Entropy(JE), Global Entropy(GE), and Global Relative Entropy(GRE) method, for performance comparison. The result shows that Otsu's and GE methods both perform better than others for Formosat-2 image. Additionally, our proposed ACCA method by selecting Otsu's method as the threshoding method has successfully extracted the cloudy pixels of Formosat-2 image for accurate cloud statistic estimation.

Hsu, Kuo-Hsien

2012-11-01

300

Resolution analysis in computational imaging with patterned illumination and bucket detection.  

PubMed

In computational imaging by pattern projection, a sequence of microstructured light patterns codified onto a programmable spatial light modulator is used to sample an object. The patterns are used as generalized measurement modes where the object information is expressed. In this Letter, we show that the resolution of the recovered image is only limited by the numerical aperture of the projecting optics regardless of the quality of the collection optics. We provide proof-of-principle experiments where the single-pixel detection strategy outperforms the resolution achieved using a conventional optical array detector for optical imaging. It is advantageous in the presence of real-world conditions, such as optical aberrations and optical imperfections in between the sample and the sensor. We provide experimental verification of image retrieval even when an optical diffuser prevents imaging with a megapixel array camera. PMID:24978763

Rodríguez, A D; Clemente, P; Irles, E; Tajahuerce, E; Lancis, J

2014-07-01

301

A framework for the automated analysis of subcellular patterns in human protein atlas images.  

PubMed

The systematic study of subcellular location patterns is required to fully characterize the human proteome, as subcellular location provides critical context necessary for understanding a protein's function. The analysis of tens of thousands of expressed proteins for the many cell types and cellular conditions under which they may be found creates a need for automated subcellular pattern analysis. We therefore describe the application of automated methods, previously developed and validated by our laboratory on fluorescence micrographs of cultured cell lines, to analyze subcellular patterns in tissue images from the Human Protein Atlas. The Atlas currently contains images of over 3000 protein patterns in various human tissues obtained using immunohistochemistry. We chose a 16 protein subset from the Atlas that reflects the major classes of subcellular location. We then separated DNA and protein staining in the images, extracted various features from each image, and trained a support vector machine classifier to recognize the protein patterns. Our results show that our system can distinguish the patterns with 83% accuracy in 45 different tissues, and when only the most confident classifications are considered, this rises to 97%. These results are encouraging given that the tissues contain many different cell types organized in different manners, and that the Atlas images are of moderate resolution. The approach described is an important starting point for automatically assigning subcellular locations on a proteome-wide basis for collections of tissue images such as the Atlas. PMID:18435555

Newberg, Justin; Murphy, Robert F

2008-06-01

302

An Imaging System Correlating Lip Shapes with Tongue Contact Patterns for Speech Pathology Research  

Microsoft Academic Search

In this research, an imaging system was built to work with a newly developed electronic device to help people produce sounds correctly. The system consists of two parts, the internal tongue contact pattern data collection and the external lip shape information analysis. The tongue position information was gathered using the palatometer, an innovative tongue contact pattern-tracking device invented by Dr.

D. J. Lee; Daniel Bates; Christopher Dromey; Xiaoqian Xu; Sameer Antani

2003-01-01

303

IR-webcam imaging and vascular pattern analysis towards hand vein authentication  

Microsoft Academic Search

Hand vein patterns are unique and universal. Vein pattern is used as biometric feature in recent years. But, it is not very much popular biometric system as compared to other systems like fingerprint, iris etc, because of the higher cost. For conventional algorithm, it is necessary to use high quality images, which demand high-priced collection devices. There are two approaches

A. Shrotri; S. C. Rethrekar; M. H. Patil; S. N. Kore

2010-01-01

304

Novel video processing schemes integrating image compression and pattern recognition  

Microsoft Academic Search

In comparison to present security applications, pattern recognition techniques can be categorized as 'hard' automatic target recognition (ATR) and 'soft' ATR. The first category has been established for years and deals with specific object recognition. On the other hand, the second, less established category operates on very fast object class-level recognition only. The second category usually employs very fast processing

Igor V. Ternovskiy; Tomasz Jannson

1997-01-01

305

Using semivariogram indices to analyse heterogeneity in spatial patterns in remotely sensed images  

NASA Astrophysics Data System (ADS)

The benchmark problem proposed in this paper is to identify regions in aerial or satellite images with geometric patterns and describe the geometric properties of the constituent elements of the pattern and their spatial distribution. This is a relevant topic in image analysis processes where spatial regular patterns are studied. This paper first presents two approaches based on multi-directional semivariograms for reducing the processing time required to compute omnidirectional semivariograms. A set of parameters for describing the structure of a semivariogram, introduced by Balaguer et al. (2010), is extracted from an experimental semivariogram and analysed to quantify the heterogeneity of the distribution of elements (trees) with periodic patterns in images of orchards. An assessment is made using four image datasets. The first dataset is composed of synthetic images that simulate regularly spaced tree crops and real images, and is used to evaluate the influence that the orientation of elements (regularly spaced trees) in the objects (crop plots) has in the descriptive parameter values. This dataset is also used to compare different semivariogram computational approaches. The other three are also composed of synthetic images and are used to evaluate the semivariogram parameters under different spatial heterogeneity conditions, and are generated by varying patterns and tree characteristics, i.e., existence or absence of faults, regular/irregular distributions, and size of the elements. Finally, the proposed methodology is applied to real aerial orthoimages of orchard plots.

Balaguer-Beser, A.; Ruiz, L. A.; Hermosilla, T.; Recio, J. A.

2013-01-01

306

Multispectral cloud-clearing using IASI sounding and collocated AVHRR imager measurements  

Microsoft Academic Search

E. S. Maddy2, T. S. King2, H. Sun2, W. W. Wolf1, C. D. Barnet1, A. Heidinger1,Z. Cheng2, and A. Gambacorta2 1NOAA\\/NESDIS\\/Center for Satellite Applications and Research, Camp Springs, Maryland, USA 2Dell, Fairfax, Virginia, USA There are several approaches for handling the effect of clouds in the IR, the most common of which include: avoiding the clouds by screening for clear-sky

E. S. Maddy; T. S. King; H. Sun; W. Wolf; C. Barnet; A. K. Heidinger; Z. Cheng; A. Gambacorta

2010-01-01

307

Interactions of the Cold and Hot ISM: Imaging the Nearest Molecular Clouds In the Local Bubble  

NASA Astrophysics Data System (ADS)

The absolute nearest molecular clouds reside within a million degree substrate known as the Local Bubble. Cold molecular gas is not typically found in isolation surrounded by hot material, but several other examples have been identified, particularly at the edges of shell structures formed by stellar winds and supernovae. These local molecular clouds located within the Local Bubble, provide a unique opportunity to study the interaction of cold and hot phases of the interstellar medium in detail. We propose a morphological study of MBM40, one the nearest molecular clouds at <80 pc, to test predictions of evaporative conduction and turbulent mixing layer theory. The morphology of these translucent clouds, measured with physical resolutions down to <100 AU due to their proximity, can be probed by 8 micron PAH emission and dust emission from the longest MIPS wavelengths (e.g., 24 and 160 microns). These observations will measure basic physical properties, such as dust opacity and temperature, as well as, gas column density. Constraints on evaporative timescales and magnetic field strengths can be estimated from the dimensions of the smallest observed size scales. In addition, these measurements may even provide limits on the physical characteristics of the hot gas itself. The proposed cloud (MBM40) is distinct from the more distant large molecular complexes because it is located within the hot Local Bubble cavity which defines the bounds of our local interstellar medium. These observations will be a unique contrasting sample to the well-observed, and more distant, traditional molecular clouds.

Redfield, Seth; Harvey, Paul; Ingalls, James; Scalo, John

2008-03-01

308

Chronometric comparison of actual and imaged complex movement patterns.  

PubMed

The authors' aim in this study was to consider the functional equivalence of internal imagery, external imagery, and action execution. Sixteen elite gymnasts imaged and performed a complex gymnastic vault. Ten performers imaged from an internal perspective, and 6 used an external perspective. Although the results revealed that the time to image the entire motor task did not significantly differ from the time required to physically perform it, irrespective of the imagery perspective used, the temporal organization of the action was different within the imagery conditions than it was in the physical condition. The results do not provide support for the principle of temporal functional equivalence. The authors discuss the results in light of recent findings from the cognitive neuroscience and psychology literatures. PMID:16968679

Calmels, Claire; Holmes, Paul; Lopez, Emilie; Naman, Véronique

2006-09-01

309

Magnetic Resonance Imaging by Synergistic Diffusion-Diffraction Patterns  

NASA Astrophysics Data System (ADS)

Inferring on the geometry of an object from its frequency spectrum is highly appealing since the object could then be imaged noninvasively or from a distance (as famously put by Kac, “can one hear the shape of a drum?”). In nuclear magnetic resonance of porous systems, the shape of the drum is represented by the pore density function that bears all the information on the collective pore microstructure. So far, conventional magnetic resonance imaging (MRI) could only detect the pore autocorrelation function, which inherently obscures fine details on the pore structure. Here, for the first time, we report on a unique imaging mechanism arising from synergistic diffusion-diffractions that directly yields the pore density function. This mechanism offers substantially higher spatial resolution compared to conventional MRI while retaining all fine details on the collective pore morphology. Thus, using these unique synergistic diffusion-diffractions, the “shape of the drum” can be inferred.

Shemesh, Noam; Westin, Carl-Fredrik; Cohen, Yoram

2012-02-01

310

Biometric verification using thermal images of palm-dorsa vein patterns  

Microsoft Academic Search

A novel approach to personal verification using the thermal images of palm-dorsa vein patterns is presented in this paper. The characteristics of the proposed method are that no prior knowledge about the objects is necessary and the parameters can be set automatically. In our work, an infrared (IR) camera is adopted as the input device to capture the thermal images

Chih-lung Lin; Kuo-chin Fan

2004-01-01

311

Genetic Algorithm-Based Relevance Feedback for Image Retrieval Using Local Similarity Patterns.  

ERIC Educational Resources Information Center

Proposes local similarity pattern (LSP) as a new method for computing digital image similarity. Topics include optimizing similarity computation based on genetic algorithm; relevance feedback; and an evaluation of LSP on five databases that showed an increase in retrieval precision over other methods for computing image similarity. (Author/LRW)

Stejic, Zoran; Takama, Yasufumi; Hirota, Kaoru

2003-01-01

312

Phase retrieval from single frame projection fringe pattern with variational image decomposition  

NASA Astrophysics Data System (ADS)

Phase retrieval from single frame projection fringe pattern is of fundamental importance, and is also a challenging problem in fringe projection measurement. In this paper, we present a new method for phase retrieval from a single frame projection fringe pattern based on variational image decomposition (VID) methods. We propose a new image decomposition model TV-G-Shearlet in order to effectively split a projection fringe pattern into background part, fringe part and noise part. The performance of the proposed approach is verified by simulated and real projection fringes as well as the comparison with the widely used and well-known Fourier transform method and wavelet transform method.

Zhu, Xinjun; Tang, Chen; Li, Biyuan; Sun, Chen; Wang, Linlin

2014-08-01

313

Direct imaging of periodic subwavelength patterns generated by optical phase masks  

SciTech Connect

We have demonstrated direct imaging of interference fringes of total atomic density with periods {lambda}/4 and {lambda}/2 for optical wavelength {lambda} that have been produced in a de Broglie wave atom interferometer. The imaging was done by means of an 'optical mask' technique, which allowed us to observe subwavelength periodic patterns with a resolution of up to {lambda}/16. In addition, the dependence of the fringe pattern on the recoil phase and pulse area reveals quantum dynamics in the atomic center-of-mass motion. The behavior of the fringe patterns near the interference times distinguishes the effects of phase gratings from those of amplitude gratings.

Tonyushkin, Alexei; Sleator, Tycho [Department of Physics, New York University, 4 Washington Place, New York, New York 10003 (United States)

2006-11-15

314

Trends in ISCCP, MISR, and MODIS cloud-top-height and optical-depth histograms  

NASA Astrophysics Data System (ADS)

In this article, temporal changes in the Multiangle Imaging Spectro Radiometer (MISR) and Moderate Resolution Imaging Spectrometer (MODIS) joint histograms of cloud-top height (CTH) and optical depth (OD) over the period 2001 to 2011 are examined. The analysis shows no significant trend in total cloud cover averaged over all oceans between 60°N and 60°S from 2001 to 2011. There are, however, significant trends in the amount of some CTH-OD histogram components or cloud types. In particular, there was an increase in the amount of cloud with intermediate optical thickness (23 > OD > 3.6) and a decrease in the amount of the most optically thick cloud (OD > 23) over this period. The total cloud amount shows no trend because the increase in the amount of intermediate optically thick clouds is nearly balanced by the decrease in the amount of the most optically thick clouds. This balance is not due to a simple shift toward optically thinner clouds in all regions but has a complex spatial pattern both regionally and vertically. An examination of the geographic distribution of the change shows that the decrease in the amount of the most optically thick cloud occurred primarily in the extratropics. International Satellite Cloud Climatology Project (ISCCP) observations are briefly compared with those from MODIS and MISR. The comparison shows that ISCCP-retrieved total-cloud fraction is reasonably robust, but changes in the ISCCP component cloud fractions sometimes show large deviations from those of MISR and MODIS.

Marchand, Roger

2013-02-01

315

Quality assessment of speckle patterns for digital image correlation  

Microsoft Academic Search

Digital image correlation (DIC) is an optical–numerical full-field displacement measuring technique, which is nowadays widely used in the domain of experimental mechanics. The technique is based on a comparison between pictures taken during loading of an object. For an optimal use of the method, the object of interest has to be covered with painted speckles. In the present paper, a

D. Lecompte; A. Smits; Sven Bossuyt; H. Sol; J. Vantomme; D. Van Hemelrijck; A. M. Habraken

2006-01-01

316

Automatic Assessment and Reduction of Noise using Edge Pattern Analysis in Non-Linear Image Enhancement  

NASA Technical Reports Server (NTRS)

Noise is the primary visibility limit in the process of non-linear image enhancement, and is no longer a statistically stable additive noise in the post-enhancement image. Therefore novel approaches are needed to both assess and reduce spatially variable noise at this stage in overall image processing. Here we will examine the use of edge pattern analysis both for automatic assessment of spatially variable noise and as a foundation for new noise reduction methods.

Jobson, Daniel J.; Rahman, Zia-Ur; Woodell, Glenn A.; Hines, Glenn D.

2004-01-01

317

Diffusion-weighted Imaging Patterns of Brain Damage Associated with Cerebral Venous Thrombosis  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Apart from cases studies, little is known regarding diffu- sion-weighted imaging of brain lesions associated with human cerebral venous thrombosis (CVT). Our aim was to describe the initial diffusion-weighted imaging patterns observed in brain areas with MR signal changes associated with CVT and to compare them with those of follow-up imaging. METHODS: The cases of nine patients

Denis Ducreux; Catherine Oppenheim; Xavier Vandamme; Didier Dormont; Yves Samson; Gerald Rancurel; Guy Cosnard; Claude Marsault

2001-01-01

318

Content-addressable holographic data storage system for invariant pattern recognition of gray-scale images.  

PubMed

Conventionally a holographic data storage system uses binary digital data as the input pages. We propose and demonstrate the use of a holographic data storage system for the purpose of invariant pattern recognition of gray-scale images. To improve the correlation accuracy for gray-scale images, we present a coding technique, phase Fourier transform (phase-FT) coding, to code a gray-scale image into a random and balanced digital binary image. In addition to the fact that a digital data page is obtained for incorporation into a holographic data storage system, this phase-FT coded image produces dc-free homogenized Fourier spectrum. This coded image can also be treated as an image for further processing, such as synthesis of distortion-invariant filters for invariant pattern recognition. A space-domain synthetic discriminant function (SDF) filter has been synthesized using these phase-FT coded images for rotation-invariant pattern recognition. Both simulation and experimental results are presented. The results show good correlation accuracy in comparison to correlation results obtained for SDF filter synthesized using the original gray-scale images themselves. PMID:20090813

Joseph, Joby; Bhagatji, Alpana; Singh, Kehar

2010-01-20

319

Patterns  

NSDL National Science Digital Library

Directions: Play the games that are listed. Do not go to another site. Be sure to take turns with your partner. First, learn to complete a pattern by playing "Which One?." Next, keep practicing patterns by playing "Pattern Mania." Finally, determine what type of pattern each set is by playing "Which pattern is it?." ...

Hinson, Mrs.

2011-10-03

320

An adaptive OPD and dislocation prediction used characteristic of interference pattern for interference hyperspectral image compression  

NASA Astrophysics Data System (ADS)

According to the imaging principle and characteristic of LASIS (Large Aperture Static Interference Imaging Spectrometer), we discovered that the 3D (three dimensional) image sequences formed by different interference pattern frames, which were formed in the imaging process of LASIS Interference hyperspectral image, had much stronger correlation than the original interference hyperspectral image sequences, either in 2D (two dimensional) spatial domain or in the spectral domain. We put this characteristic into image compression and proposed an adaptive OPD (optical path difference) and dislocation prediction algorithm for interference hyperspectral image compression. Compared the new algorithm proposed in this paper with Dual-Direction Prediction [1] proposed in 2009, lots of experimental results showed that the prediction error entropy of the new algorithm was much smaller. In the prediction step of lifting wavelet transform, this characteristic would also reduce the entropy of coefficients in high frequency significantly, which would be more advantageous for quantification coding [2].

Wen, Jia; Ma, Caiwen; Shui, Penglang

2011-09-01

321

Sensitivity of Satellite-Retrieved Cloud Properties to the Effective Variance of Cloud Droplet Size Distribution  

SciTech Connect

Cloud reflectance models currently used in cloud property retrievals from satellites have been developed using size distributions defined by a set of fixed effective radii with a fixed effective variance. The satellite retrievals used for the Atmospheric Radiation Measurement (ARM) program assume droplet size distributions with an effective variance value of 0.10 (Minnis et al. 1998); the International Satellite Cloud Climatology Project uses 0.15 (Rossow and Schiffer 1999); and the Moderate Resolution Imaging Spectroradiometer (MODIS) team uses 0.13 (Nakajima and King 1990). These distributions are not necessarily representative of the actual sizes present in the clouds being observed. Because the assumed distributions can affect the reflectance patterns and near-infrared absorption, even for the same droplet effective radius reff, it is desirable to use the optimal size distributions in satellite retrievals of cloud properties. Collocated observations of the same clouds from different geostationary satellites, at different viewing angles, indicate that the current models may not be optimal (Ayers et al. 2005). Similarly, hour-to-hour variations in effective radius and optical depth reveal an unexplained dependence on scattering angle. To explore this issue, this paper examines the sensitivity of the cloud reflectance at 0.65 and 3.90-{micro}m to changes in the effective variance, or the spectral dispersion, of the modeled size distributions. The effects on the scattering phase functions and on the cloud reflectances are presented, as well as some resultant effects on the retrieved cloud properties.

Arduini, R.F.; Minnis, P.; Smith, W.L.Jr.; Ayers, J.K.; Khaiyer, M.M.; Heck, P.

2005-03-18

322

Microphysical Analysis using Airborne 2-D Cloud and Precipitation Imaging Probe Data  

NASA Astrophysics Data System (ADS)

The NOAA P-3 instrumented aircraft provided in-situ cloud and precipitation microphysical observations during the DYNAMO (Dynamics of the Madden-Julian Oscillation) field experiment. The Particle Measuring System 2D cloud (2D-C) and precipitation (2D-P) probes collected data for particles between 12.5 ?m - 1.55 mm (25 ?m resolution) and 100 ?m - 6.2 mm (100 ?m resolution), respectively. Spectra from each instrument were combined to provide a broad distribution of precipitation particle sizes. The 'method of moments' technique was used to analyze drop size distribution (DSD) spectra, which were modeled by fitting a three-parameter (slope, shape, and intercept) gamma distribution to the spectra. The characteristic shape of the mean spectrum compares to previous maritime measurements. DSD variability will be presented with respect to the temporal evolution of cloud populations during a Madden-Julian Oscillation (MJO) event, as well as in-situ aircraft vertical wind velocity measurements. Using the third and sixth moments, rainfall rate (R) and equivalent radar reflectivity factor (Z), respectively, were computed for each DSD. Linear regression was applied to establish a Z-R relationship for the data for the estimation of precipitation. The study indicated unique characteristics of microphysical processes for this region. These results are important to continue to define the cloud population characteristics in the climatological MJO region. Improved representation of the cloud characteristics on the microphysical scale will serve as a check to model parameterizations, helping to improve numerical simulations.

Guy, N.; Jorgensen, D.; Witte, M.; Chuang, P. Y.; Black, R. A.

2013-12-01

323

Review of MR image segmentation techniques using pattern recognition.  

PubMed

This paper has reviewed, with somewhat variable coverage, the nine MR image segmentation techniques itemized in Table II. A wide array of approaches have been discussed; each has its merits and drawbacks. We have also given pointers to other approaches not discussed in depth in this review. The methods reviewed fall roughly into four model groups: c-means, maximum likelihood, neural networks, and k-nearest neighbor rules. Both supervised and unsupervised schemes require human intervention to obtain clinically useful results in MR segmentation. Unsupervised techniques require somewhat less interaction on a per patient/image basis. Maximum likelihood techniques have had some success, but are very susceptible to the choice of training region, which may need to be chosen slice by slice for even one patient. Generally, techniques that must assume an underlying statistical distribution of the data (such as LML and UML) do not appear promising, since tissue regions of interest do not usually obey the distributional tendencies of probability density functions. The most promising supervised techniques reviewed seem to be FF/NN methods that allow hidden layers to be configured as examples are presented to the system. An example of a self-configuring network, FF/CC, was also discussed. The relatively simple k-nearest neighbor rule algorithms (hard and fuzzy) have also shown promise in the supervised category. Unsupervised techniques based upon fuzzy c-means clustering algorithms have also shown great promise in MR image segmentation. Several unsupervised connectionist techniques have recently been experimented with on MR images of the brain and have provided promising initial results. A pixel-intensity-based edge detection algorithm has recently been used to provide promising segmentations of the brain. This is also an unsupervised technique, older versions of which have been susceptible to oversegmenting the image because of the lack of clear boundaries between tissue types or finding uninteresting boundaries between slightly different types of the same tissue. To conclude, we offer some remarks about improving MR segmentation techniques. The better unsupervised techniques are too slow. Improving speed via parallelization and optimization will improve their competitiveness with, e.g., the k-nn rule, which is the fastest technique covered in this review. Another area for development is dynamic cluster validity. Unsupervised methods need better ways to specify and adjust c, the number of tissue classes found by the algorithm. Initialization is a third important area of research. Many of the schemes listed in Table II are sensitive to good initialization, both in terms of the parameters of the design, as well as operator selection of training data.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8413011

Bezdek, J C; Hall, L O; Clarke, L P

1993-01-01

324

Reducing the resolution bias in cloud fraction from satellite derived clear-conservative cloud masks  

NASA Astrophysics Data System (ADS)

Clear-conservative satellite cloud detection algorithms overestimate cloud fraction (CF), the degree to which depends on instrument resolution and the spatial distribution of cloud area, with boundary layer cumulus carrying the largest overestimation. This is because in the standard method of computing CF, partially cloudy pixels contribute in the amount of the pixel's area rather than the true cloud area. Development of analytical and pattern recognition techniques to reduce overestimation has been limited by the lack of coincident long-term, large scale, and high-resolution satellite data sets. Such data sets are now available from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Multiangle Imaging SpectroRadiometer (MISR) instruments onboard the satellite, Terra. These data sets are used to determine the resolution required to reduce the CF overestimation to ?0.01 absolute CF using the standard, analytical, and pattern recognition techniques on perfect, clear-conservative cloud masks with future instrument design in mind; investigate the challenges of implementing these techniques on MISR's operational clear-conservative cloud mask; and demonstrate the impact of these techniques on a MISR-derived CF climatology similar to those used to evaluate climate models. Reducing the median CF bias to ?0.01 requires resolutions of <45 m and ?80 m for the standard and analytical techniques, respectively, while the pattern recognition technique has no resolution requirement up to a resolution of 1.2 km. When the pattern recognition technique is applied to 10-year, December, low cloud climatologies over the tropical Western Atlantic (10°N-20°N and 50°W-60°W) derived from MISR, the average CF reduces from 0.50 to 0.20. This is a large reduction in cloud fraction, particularly when considering the climate sensitivity to low clouds and the use of satellite derived CF climatologies for evaluation of climate model CF and radiative budgets.

Jones, Alexandra L.; di Girolamo, Larry; Zhao, Guangyu

2012-06-01

325

[A cloud detection algorithm for MODIS images combining Kmeans clustering and multi-spectral threshold method].  

PubMed

An improved method for detecting cloud combining Kmeans clustering and the multi-spectral threshold approach is described. On the basis of landmark spectrum analysis, MODIS data is categorized into two major types initially by Kmeans method. The first class includes clouds, smoke and snow, and the second class includes vegetation, water and land. Then a multi-spectral threshold detection is applied to eliminate interference such as smoke and snow for the first class. The method is tested with MODIS data at different time under different underlying surface conditions. By visual method to test the performance of the algorithm, it was found that the algorithm can effectively detect smaller area of cloud pixels and exclude the interference of underlying surface, which provides a good foundation for the next fire detection approach. PMID:21714260

Wang, Wei; Song, Wei-Guo; Liu, Shi-Xing; Zhang, Yong-Ming; Zheng, Hong-Yang; Tian, Wei

2011-04-01

326

Clinician image review patterns in an outpatient setting  

NASA Astrophysics Data System (ADS)

We have previously described a system for delivering radiology information to the desktop computers used for the electronic medical record (EMR). The system was built with the ability to record physician usage to a database. This usage information was then studied to help understand the value and requirements of an application that could display radiology information on the EMR workstations. This system was used by both primary care physicians and specialists primarily in the out-patient setting. We found that while there was substantial variation in usage both within and between the two physician groups, there was a high degree of support for maintaining image display capabilities on the workstations.

Erickson, Bradley J.; Ryan, William J.; Gehring, Dale G.; Beebe, Calvin

1998-07-01

327

Multichannel analysis of correlation length of SEVIRI images around ground-based cloud observatories to determine their representativeness  

NASA Astrophysics Data System (ADS)

Images of the geostationary Meteosat-9 SEVIRI instrument during the year 2012 are analyzed with respect to the representativeness of the observations of eight cloud observatories in Europe. Cloudy situations are selected to get a time series for every pixel in a 300 km × 300 km area centered around each ground station. Then the Pearson correlation coefficient of each time series to the one of the pixel nearest to the corresponding ground site is calculated. The area for which a station is representative is defined by the characteristic radius around each station for each SEVIRI channel, where the average correlation falls below 0.9. It is found that measurements in the visible and near infrared channels, which respond to cloud microphysics, are correlated in an area with a 1 to 4 km radius, while the thermal channels, that correspond to cloud top temperature, are correlated to a distance of about 20 km. The defined radius even increases for the water vapor and ozone channels. While all stations in Central Europe are quite alike, the correlations around the station in the mountains of southern Italy are much lower. Additionally correlations at different distances corresponding to the grid box sizes of forecast models were compared. The results show good comparability between regional forecast models (grid size ≲ 10 km) and ground-based measurements since the correlations in less than 10 km distance are in all cases higher than 0.8. For larger distances like they are typical for global models (grid size ≳ 20 km) the correlations decrease to 0.6, especially for shortwave measurements and corresponding cloud products. By comparing daily means, the characteristic radius of each station is increased to about 3 to 10 times the value of instantaneous measurements and also the comparability to models grows.

Slobodda, J.; Hünerbein, A.; Lindstrot, R.; Preusker, R.; Ebell, K.; Fischer, J.

2014-06-01

328

Classification of patterns for diffuse lung diseases in thoracic CT images by AdaBoost algorithm  

NASA Astrophysics Data System (ADS)

CT images are considered as effective for differential diagnosis of diffuse lung diseases. However, the diagnosis of diffuse lung diseases is a difficult problem for the radiologists, because they show a variety of patterns on CT images. So, our purpose is to construct a computer-aided diagnosis (CAD) system for classification of patterns for diffuse lung diseases in thoracic CT images, which gives both quantitative and objective information as a second opinion, to decrease the burdens of radiologists. In this article, we propose a CAD system based on the conventional pattern recognition framework, which consists of two sub-systems; one is feature extraction part and the other is classification part. In the feature extraction part, we adopted a Gabor filter, which can extract patterns such like local edges and segments from input textures, as a feature extraction of CT images. In the recognition part, we used a boosting method. Boosting is a kind of voting method by several classifiers to improve decision precision. We applied AdaBoost algorithm for boosting method. At first, we evaluated each boosting component classifier, and we confirmed they had not enough performances in classification of patterns for diffuse lung diseases. Next, we evaluated the performance of boosting method. As a result, by use of our system, we could improve the classification rate of patterns for diffuse lung diseases.

Kuwahara, Masayuki; Kido, Shoji; Shouno, Hayaru

2009-02-01

329

SPEX2: automated concise extraction of spatial gene expression patterns from Fly embryo ISH images  

PubMed Central

Motivation: Microarray profiling of mRNA abundance is often ill suited for temporal–spatial analysis of gene expressions in multicellular organisms such as Drosophila. Recent progress in image-based genome-scale profiling of whole-body mRNA patterns via in situ hybridization (ISH) calls for development of accurate and automatic image analysis systems to facilitate efficient mining of complex temporal–spatial mRNA patterns, which will be essential for functional genomics and network inference in higher organisms. Results: We present SPEX2, an automatic system for embryonic ISH image processing, which can extract, transform, compare, classify and cluster spatial gene expression patterns in Drosophila embryos. Our pipeline for gene expression pattern extraction outputs the precise spatial locations and strengths of the gene expression. We performed experiments on the largest publicly available collection of Drosophila ISH images, and show that our method achieves excellent performance in automatic image annotation, and also finds clusters that are significantly enriched, both for gene ontology functional annotations, and for annotation terms from a controlled vocabulary used by human curators to describe these images. Availability: Software will be available at http://www.sailing.cs.cmu.edu/ Contact: epxing@cs.cmu.edu Supplementary information: Supplementary data are avilable at Bioinformatics online.

Puniyani, Kriti; Faloutsos, Christos; Xing, Eric P.

2010-01-01

330

Modeling time-dependent obscuration for simulated imaging of dust and smoke clouds  

Microsoft Academic Search

Time and spatial variations in atmospheric aerosol plumes can be factors in the effectiveness of electro-optical (EO) systems. Of particular interest are obscuration statistics including the frequency and duration of optically thick and optically thin cloud regions that intermittently affect sensor operation. Related to this problem is an increasing use of modern visualization techniques in simulations and computer graphics to

Donald W. Hoock

1991-01-01

331

Automatic Procedure for the Registration of Thermographic Images with Point Clouds  

NASA Astrophysics Data System (ADS)

This paper presents a procedure for the automatic registration of thermographies with laser scanning point clouds. Given the heterogeneous nature of the two modalities, we propose a feature-based approach, satisfying the requisite that extracted features have to be invariant not only to rotation, translation and scale but also to changes in illumination and dimensionality. As speed and minimum operator interaction are prerequisites for the viability of the process in the building industry, our automatic registration procedure includes automatic feature extraction with no human intervention. With this aim, a line segment detector is used to extract 2D lines from thermographies, and 3D lines are extracted through segmentation of the point cloud. Feature-matching and the relative pose between thermographies and point cloud are obtained from an iterative procedure applied to detect and reject outliers; this includes rotation matrix and translation vector calculation and the application of the RANSAC algorithm to find a consistent set of matches. An automatically textured thermographic 3D model is the expected result of these procedures once the point cloud is filtered and triangulated.

Lagüela, S.; Armesto, J.; Arias, P.; Zakhor, A.

2012-07-01

332

Computation of cloud base height from paired whole-sky imaging cameras.  

National Technical Information Service (NTIS)

A major goal for global change studies is to improve the accuracy of general circulation models (GCMs) capable of predicting the timing and magnitude of greenhouse gas-induced global warming. Research has shown that cloud radiative feedback is the single ...

M. C. Allmen W. P. Kegelmeyer

1994-01-01

333

Cassini Imaging Observations of Lakes and Clouds at Titan's High Latitudes and the Implications of the Changes Therein  

NASA Astrophysics Data System (ADS)

Cassini's Imaging Science Subsystem (ISS) imaged Titan's south polar region in July 2004 and June 2005, revealing convective cloud systems and dark surface features interpreted to be hydrocarbon lakes, e.g. 235- km-long Ontario Lacus (McEwen et al., B.A.A.S. 37, 2005). Recent evidence from Cassini's Visual and Infrared Mapping Spectrometer supports the interpretation that Ontario Lacus contains liquid ethane and methane (Brown et al., Nature 454, 2008). Although diffuse clouds or atmospheric scattering could play a role, differences between the two ISS observations taken a year apart may be due to changes in the lakes as a result of precipitation from a large cloud system observed in Fall 2004 (Schaller et al., Icarus 182, 2006). ISS observations of northern latitudes just emerging from northern winter have revealed much larger dark areas, including Mare Kraken (>1100 km long), as well as myriad smaller dark spots. Many of these features coincide with liquid-filled areas identified by Cassini RADAR (e.g., Lopes et al., EOS 88, 2007). Combined these features cover well over 600,000 km2, ~1% of Titan's surface area; however, as shown by Lorenz et al. (GRL 35, 2008), even if all were filled with liquid, they would not provide enough methane to keep Titan's atmosphere resupplied for a substantial amount of time, unless they are unexpectedly deep or other subsurface reservoirs exist. Intriguingly the surface coverage is unevenly distributed, with more total area and much larger seas occurring around the North (recently winter) Pole. The extents to which this variation depends on the season and/or local geology and its effects on atmospheric circulation may be revealed with the advent of northern spring and summer.

Turtle, E. P.; Perry, J. E.; McEwen, A. S.; Del Genio, A. D.; Barbara, J.; West, R. A.; Dawson, D. D.; Porco, C. C.

2008-12-01

334

Cardiac electrophysiological activation pattern estimation from images using a patient-specific database of synthetic image sequences.  

PubMed

While abnormal patterns of cardiac electrophysiological activation are at the origin of important cardiovascular diseases (e.g., arrhythmia, asynchrony), the only clinically available method to observe detailed left ventricular endocardial surface activation pattern is through invasive catheter mapping. However, this electrophysiological activation controls the onset of the mechanical contraction; therefore, important information about the electrophysiology could be deduced from the detailed observation of the resulting motion patterns. In this paper, we present the study of this inverse cardiac electrokinematic relationship. The objective is to predict the activation pattern knowing the cardiac motion from the analysis of cardiac image sequences. To achieve this, we propose to create a rich patient-specific database of synthetic time series of the cardiac images using simulations of a personalized cardiac electromechanical model, in order to study this complex relationship between electrical activity and kinematic patterns in the context of this specific patient. We use this database to train a machine-learning algorithm which estimates the depolarization times of each cardiac segment from global and regional kinematic descriptors based on displacements or strains and their derivatives. Finally, we use this learning to estimate the patient’s electrical activation times using the acquired clinical images. Experiments on the inverse electrokinematic learning are demonstrated on synthetic sequences and are evaluated on clinical data with promising results. The error calculated between our prediction and the invasive intracardiac mapping ground truth is relatively small (around 10 ms for ischemic patients and 20 ms for nonischemic patient). This approach suggests the possibility of noninvasive electrophysiological pattern estimation using cardiac motion imaging. PMID:24058008

Prakosa, Adityo; Sermesant, Maxime; Allain, Pascal; Villain, Nicolas; Rinaldi, C Aldo; Rhode, Kawal; Razavi, Reza; Delingette, Hervé; Ayache, Nicholas

2014-02-01

335

BIOCAT: a pattern recognition platform for customizable biological image classification and annotation  

PubMed Central

Background Pattern recognition algorithms are useful in bioimage informatics applications such as quantifying cellular and subcellular objects, annotating gene expressions, and classifying phenotypes. To provide effective and efficient image classification and annotation for the ever-increasing microscopic images, it is desirable to have tools that can combine and compare various algorithms, and build customizable solution for different biological problems. However, current tools often offer a limited solution in generating user-friendly and extensible tools for annotating higher dimensional images that correspond to multiple complicated categories. Results We develop the BIOimage Classification and Annotation Tool (BIOCAT). It is able to apply pattern recognition algorithms to two- and three-dimensional biological image sets as well as regions of interest (ROIs) in individual images for automatic classification and annotation. We also propose a 3D anisotropic wavelet feature extractor for extracting textural features from 3D images with xy-z resolution disparity. The extractor is one of the about 20 built-in algorithms of feature extractors, selectors and classifiers in BIOCAT. The algorithms are modularized so that they can be “chained” in a customizable way to form adaptive solution for various problems, and the plugin-based extensibility gives the tool an open architecture to incorporate future algorithms. We have applied BIOCAT to classification and annotation of images and ROIs of different properties with applications in cell biology and neuroscience. Conclusions BIOCAT provides a user-friendly, portable platform for pattern recognition based biological image classification of two- and three- dimensional images and ROIs. We show, via diverse case studies, that different algorithms and their combinations have different suitability for various problems. The customizability of BIOCAT is thus expected to be useful for providing effective and efficient solutions for a variety of biological problems involving image classification and annotation. We also demonstrate the effectiveness of 3D anisotropic wavelet in classifying both 3D image sets and ROIs.

2013-01-01

336

Full wafer macro-CD imaging for excursion control of fast patterning processes  

NASA Astrophysics Data System (ADS)

A powerful new inspection technology enables the excursion control of fast patterning processes. Full images of 300mm wafers are captured and processed to extract CD uniformity information of contact hole and line-space patterns. Suitable masking filters are applied to process and analyze the information from active logic and/or memory areas separately. Characteristic process tool signatures can then be detected based on die, exposure field and wafer-level pattern variations. Based on inspection times of a few seconds per wafer, rapid monitoring of 100% of processed wafers at full surface is feasible. CD-imaging is demonstrated for the monitoring of key patterning process steps in gate formation. Use cases for stand-alone, integrated and smart sampling strategies are discussed.

Markwort, Lars; Kappel, Christoph; Kharrazian, Reza; Guittet, Pierre-Yves

2010-03-01

337

Method for reducing Newton's rings pattern in the scanned image reproduced with film scanners  

NASA Astrophysics Data System (ADS)

Newton's rings pattern always blurs the scanned image when scanning a film using a film scanner. Such phenomenon is a kind of equal thickness interference, which is caused by the air layer between the film and the glass of the scanner. A lot of methods were proposed to prevent the interference, such as film holder, anti-Newton's rings glass and emulsion direct imaging technology, etc. Those methods are expensive and lack of flexibility. In this paper, Newton's rings pattern is proved to be a 2-D chirp signal. Then, the fractional Fourier transform, which can be understood as the chirp-based decomposition, is introduced to process Newton's rings pattern. A digital filtering method in the fractional Fourier domain is proposed to reduce the Newton's rings pattern. The effectiveness of the proposed method is verified by simulation. Compared with the traditional optical method, the proposed method is more flexible and low cost.

Lu, Ming-feng; Ni, Guo-qiang; Wang, Tao; Zhang, Feng; Tao, Ran; Yuan, Jun

2013-12-01

338

Ammonia Clouds on Jupiter  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter

In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

2007-01-01

339

Extraction and comparison of gene expression patterns from 2D RNA in situ hybridization images  

PubMed Central

Motivation: Recent advancements in high-throughput imaging have created new large datasets with tens of thousands of gene expression images. Methods for capturing these spatial and/or temporal expression patterns include in situ hybridization or fluorescent reporter constructs or tags, and results are still frequently assessed by subjective qualitative comparisons. In order to deal with available large datasets, fully automated analysis methods must be developed to properly normalize and model spatial expression patterns. Results: We have developed image segmentation and registration methods to identify and extract spatial gene expression patterns from RNA in situ hybridization experiments of Drosophila embryos. These methods allow us to normalize and extract expression information for 78 621 images from 3724 genes across six time stages. The similarity between gene expression patterns is computed using four scoring metrics: mean squared error, Haar wavelet distance, mutual information and spatial mutual information (SMI). We additionally propose a strategy to calculate the significance of the similarity between two expression images, by generating surrogate datasets with similar spatial expression patterns using a Monte Carlo swap sampler. On data from an early development time stage, we show that SMI provides the most biologically relevant metric of comparison, and that our significance testing generalizes metrics to achieve similar performance. We exemplify the application of spatial metrics on the well-known Drosophila segmentation network. Availability: A Java webstart application to register and compare patterns, as well as all source code, are available from: http://tools.genome.duke.edu/generegulation/image_analysis/insitu Contact: uwe.ohler@duke.edu Supplementary information: Supplementary data are available at Bioinformatics online.

Mace, Daniel L.; Varnado, Nicole; Zhang, Weiping; Frise, Erwin; Ohler, Uwe

2010-01-01

340

Spatial and Temporal Distribution of Clouds Observed by MODIS Onboard the Terra and Aqua Satellites  

NASA Technical Reports Server (NTRS)

The Moderate Resolution Imaging Spectroradiometer (MODIS) was developed by NASA and launched aboard the Terra spacecraft on December 18, 1999 and Aqua spacecraft on May 4, 2002. A comprehensive set of remote sensing algorithms for the retrieval of cloud physical and optical properties have enabled over twelve years of continuous observations of cloud properties from Terra and over nine years from Aqua. The archived products from these algorithms include 1 km pixel-level (Level-2) and global gridded Level-3 products. In addition to an extensive cloud mask, products include cloud-top properties (temperature, pressure, effective emissivity), cloud thermodynamic phase, cloud optical and microphysical parameters (optical thickness, effective particle radius, water path), as well as derived statistics. Results include the latitudinal distribution of cloud optical and radiative properties for both liquid water and ice clouds, as well as latitudinal distributions of cloud top pressure and cloud top temperature. MODIS finds the cloud fraction, as derived by the cloud mask, is nearly identical during the day and night, with only modest diurnal variation. Globally, the cloud fraction derived by the MODIS cloud mask is approx.67%, with somewhat more clouds over land during the afternoon and less clouds over ocean in the afternoon, with very little difference in global cloud cover between Terra and Aqua. Overall, cloud fraction over land is approx.55%, with a distinctive seasonal cycle, whereas the ocean cloudiness is much higher, around 72%, with much reduced seasonal variation. Cloud top pressure and temperature have distinct spatial and temporal patterns, and clearly reflect our understanding of the global cloud distribution. High clouds are especially prevalent over the northern hemisphere continents between 30 and 50 . Aqua and Terra have comparable zonal cloud top pressures, with Aqua having somewhat higher clouds (cloud top pressures lower by 100 hPa) over land due to afternoon deep convection. The coldest cloud tops (colder than 230 K) generally occur over Antarctica and the high clouds in the tropics (ITCZ and the deep convective clouds over the western tropical Pacific and Indian sub-continent).

King, Michael D.; Platnick, Steven; Menzel, W. Paul; Ackerman, Steven A.; Hubanks, Paul A.

2012-01-01

341

Development of Patterns for Digital Image Correlation Measurements at Reduced Length Scales  

Microsoft Academic Search

Methods for patterning metal thin films at the microscale and nanoscale by applying the patterns to metallic and polymeric\\u000a materials for use in shape and deformation measurements in a scanning electron microsope (SEM) or other high magnification\\u000a imaging system are described. In one approach, thin films of metallic materials (e.g., Au, Ag, Cu, and Cr) are applied to\\u000a a variety

W. A. Scrivens; Y. Luo; M. A. Sutton; S. A. Collette; M. L. Myrick; P. Miney; P. E. Colavita; A. P. Reynolds; X. Li

2007-01-01

342

Local spatial binary pattern: a new feature descriptor for content-based image retrieval  

NASA Astrophysics Data System (ADS)

In this paper, we propose a novel image retrieval algorithm using local spatial binary patterns (LSBP) for contentbased image retrieval. The traditional local binary pattern (LBP) encodes the relationship between the referenced pixel and its surrounding neighbors by calculating gray-level difference, but LBP lacks the spatial distribution information of texture direction. The proposed method encodes spatial relationship of the referenced pixel and its neighbors, based on the gray-level variation patterns of the horizontal, vertical and oblique directions. Additionally, variation between center pixel and its surrounding neighbors is calculated to reflect the magnitude information of the whole image. We compare our method with LBP, uniform LBP (ULBP), completed LBP (CLBP), local ternary pattern (LTP) and local tetra patterns (LTrP) based on three benchmark image databases including, Brodatz texture database(DB1), Corel database(DB2), and MIT VisTex database(DB3). Experiment analysis shows that the proposed method improves the retrieval results from 70.49%/41.30% to 73.26%/46.26% in terms of average precision/average recall on database DB2, from 79.02% to 85.92% and 82.14% to 90.88% in terms of average precision on databases DB1 and DB3, respectively, as compared with the traditional LBP.

Xia, Yu; Wan, Shouhong; Yue, Lihua

2014-01-01

343

Model-based classification methods of global patterns in dermoscopic images.  

PubMed

In this paper different model-based methods of classification of global patterns in dermoscopic images are proposed. Global patterns identification is included in the pattern analysis framework, the melanoma diagnosis method most used among dermatologists. The modeling is performed in two senses: first a dermoscopic image is modeled by a finite symmetric conditional Markov model applied to L?a?b? color space and the estimated parameters of this model are treated as features. In turn, the distribution of these features are supposed that follow different models along a lesion: a Gaussian model, a Gaussian mixture model, and a bag-of-features histogram model. For each case, the classification is carried out by an image retrieval approach with different distance metrics. The main objective is to classify a whole pigmented lesion into three possible patterns: globular, homogeneous, and reticular. An extensive evaluation of the performance of each method has been carried out on an image database extracted from a public Atlas of Dermoscopy. The best classification success rate is achieved by the Gaussian mixture model-based method with a 78.44% success rate in average. In a further evaluation the multicomponent pattern is analyzed obtaining a 72.91% success rate. PMID:24770918

Sáez, Aurora; Serrano, Carmen; Acha, Begoña

2014-05-01

344

Spatial pattern separation of chemicals and frequency-independent components by terahertz spectroscopic imaging  

NASA Astrophysics Data System (ADS)

We separated the component spatial patterns of frequency-dependent absorption in chemicals and frequency-independent components such as plastic, paper, and measurement noise in terahertz (THz) spectroscopic images, using known spectral curves. Our measurement system, which uses a widely tunable coherent THz-wave parametric oscillator source, can image at a specific frequency in the range 1-2 THz. The component patterns of chemicals can easily be extracted by use of the frequency-independent components. This method could be successfully used for nondestructive inspection for the detection of illegal drugs and devices of bioterrorism concealed, e.g., inside mail and packages.

Watanabe, Yuuki; Kawase, Kodo; Ikari, Tomofumi; Ito, Hiromasa; Ishikawa, Youichi; Minamide, Hiroaki

2003-10-01

345

Speckle pattern of the images of objects exposed to monochromatic coherent terahertz radiation  

SciTech Connect

By using a free electron laser and a microbolometer array, real-time images are recorded for the first time in the terahertz range at the rate of up to 90 frames per second. In the case of diffusive illumination of objects by coherent monochromatic radiation, the images consist of speckles. The study of the statistical properties of speckle patterns shows that they are quite accurately described by the theory developed for speckles in the visible range. By averaging a set of images with the help of a rotating scatterer during the exposure time of a frame (20 ms) and by summing statistically independent speckle patterns of many frames, images of the acceptable quality are obtained. The possibilities of terahertz speckle photography and speckle interferometry are discussed. (terahertz radiation)

Vinokurov, Nikolai A; Knyazev, Boris A; Kulipanov, Gennadii N [G.I. Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Dem'yanenko, M A; Esaev, D G [A.V.Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Chashchina, O I; Cherkasskii, Valerii S [Novosibirsk State University, Novosibirsk (Russian Federation)

2009-05-31

346

Exposure latitude analysis for dense line and space patterns by using diffused aerial image model  

NASA Astrophysics Data System (ADS)

Ultimate limitation of lithography has been studied by using the diffused aerial image model (DAIM). Assuming that only the 0th and 1st order diffraction beams in the off-axis illumination technique contribute to the resist patterns, aerial image is calculated for dense line and space patterns. And then DAIM is applied to achieve final image. By using this diffused aerial image, exposure latitude and mask error effect can be analyzed quantitatively. In the case of perfect image, which can be achieved from, for example, diffraction free x-ray lithography or electron beam lithography without Coulomb repulsion and back scattering effect, same approaches are possible to get the exposure latitude and mask error effect. Under the validation of DAIM, most important parameter, which characterizes dense L/S patterns, is the diffusion length of acid. In order to realize sub-o.1 micrometers pattern with enough process margins, it is required to enlarge exposure latitude and to reduce mask error effect. Therefore, reducing h acid diffusion length of chemical amplification resist (CAR) or new conceptual resist instead of CAR will be needed for sub-0.1 micrometers era.

Ahn, Chang-Nam; Kim, Hee-Bom; Baik, Ki-Ho

2000-07-01

347

Automated recognition of patterns characteristic of subcellular structures in fluorescence microscopy images.  

PubMed

Methods for numerical description and subsequent classification of cellular protein localization patterns are described. Images representing the localization patterns of 4 proteins and DNA were obtained using fluorescence microscopy and divided into distinct training and test sets. The images were processed to remove out-of-focus and background fluorescence and 2 sets of numeric features were generated: Zernike moments and Haralick texture features. These feature sets were used as inputs to either a classification tree or a neural network. Classifier performance (the average percent of each type of image correctly classified) on previously unseen images ranged from 63% for a classification tree using Zernike moments to 88% for a backpropagation neural network using a combination of features from the 2 feature sets. These results demonstrate the feasibility of applying pattern recognition methods to subcellular localization patterns, enabling sets of previously unseen images from a single class to be classified with an expected accuracy greater than 99%. This will provide not only a new automated way to describe proteins, based on localization rather than sequence, but also has potential application in the automation of microscope functions and in the field of gene discovery. PMID:9822349

Boland, M V; Markey, M K; Murphy, R F

1998-11-01

348

Cloud Interactions  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 1 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

This image was acquired during mid-spring near the North Pole. The linear water-ice clouds are now regional in extent and often interact with neighboring cloud system, as seen in this image. The bottom of the image shows how the interaction can destroy the linear nature. While the surface is still visible through most of the clouds, there is evidence that dust is also starting to enter the atmosphere.

Image information: VIS instrument. Latitude 68.4, Longitude 258.8 East (101.2 West). 38 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

349

Remote sensing of cloud, aerosol, and water vapor properties from the moderate resolution imaging spectrometer (MODIS)  

NASA Technical Reports Server (NTRS)

The authors describe the status of MODIS-N and its companion instrument MODIS-T (tilt), a tiltable cross-track scanning spectrometer with 32 uniformly spaced channels between 0.410 and 0.875 micron. They review the various methods being developed for the remote sensing of atmospheric properties using MODIS, placing primary emphasis on the principal atmospheric applications of determining the optical, microphysical, and physical properties of clouds and aerosol particles from spectral reflection and thermal emission measurements. In addition to cloud and aerosol properties, MODIS-N will be used for determining the total precipitable water vapor and atmospheric stability. The physical principles behind the determination of each of these atmospheric products are described, together with an example of their application to aircraft and/or satellite measurements.

King, Michael D.; Kaufman, Yoram J.; Menzel, W. Paul; Tanre, Didier D.

1992-01-01

350

Deep optical and near infrared imaging photometry of the Serpens cloud core  

NASA Astrophysics Data System (ADS)

We present results from a deep optical (VRI) and near infrared (JHK) survey of the central part of the Serpens molecular cloud. A total of 138 sources were detected in the 19 arcmin(2) surveyed area down to a limiting magnitude of 16.3 in K. We find that the form of the observed K Luminosity Function (KLF) of stars belonging to the Serpens Molecular cloud is consistent with that predicted from a Miller & Scalo (1979) Interstellar Mass Function (IMF). We have investigated the KLF evolution with the age of a cluster by modeling KLFs of hypothetical clusters. Our results suggest that two phases of star formation could have taken place in the Serpens core. Table 2 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

Giovannetti, P.; Caux, E.; Nadeau, D.; Monin, J.-L.

1998-02-01

351

Cloud Images and Turbulent Spectra Taken by the NRL 94 GHz WARLOC Radar  

Microsoft Academic Search

Gyroklystron development has been reported at APS DPP meetings for years. One of these, a 94 GHz, 100 kW gyroklystron has been incorporated into an NRL radar system called WARLOC, situated on the west shore of Chesapeake Bay. One application of WARLOC has been the study of clouds[1,2]. The added power of the gyroklystron has made possible the rapid resolution

Wallace Manheimer

2003-01-01

352

Cloud computing platform for GIS image processing in U-city  

Microsoft Academic Search

Ubiquitous city (U-city) is a city with ubiquitous information technology that enables citizens to access the converged information anywhere and anytime. A lot of compute power are required in U-city, because large amount of data should be processed in real-time. Cloud computing enables users to use the abstracted and virtualized computing resources and to process huge amount of information without

Jong Won Park; Chang Ho Yun; Shin-gyu Kim; Heon Y. Yeom; Yong Woo Lee

2011-01-01

353

Laboratory measurements of light scattered by clouds and layers of solid particles using an imaging technique  

Microsoft Academic Search

\\u000a The Optical PRoperties of Astronomical and Atmospheric Grains (PROGRA2) experiment was developed in 1993 to study the light scattered by dust clouds, with an emphasis on its linear polarization.\\u000a The instrument was progressively improved. A short description of the PROGRA2-vis instrument operating in the visible is given in this chapter. In the framework of the experiment, solid particles are\\u000a lifted

E. Hadamcik; J.-B. Renard; A. C. Levasseur-Regourd; J. Lasue

354

Automated annotation of developmental stages of Drosophila embryos in images containing spatial patterns of expression  

PubMed Central

Motivation: Drosophila melanogaster is a major model organism for investigating the function and interconnection of animal genes in the earliest stages of embryogenesis. Today, images capturing Drosophila gene expression patterns are being produced at a higher throughput than ever before. The analysis of spatial patterns of gene expression is most biologically meaningful when images from a similar time point during development are compared. Thus, the critical first step is to determine the developmental stage of an embryo. This information is also needed to observe and analyze expression changes over developmental time. Currently, developmental stages (time) of embryos in images capturing spatial expression pattern are annotated manually, which is time- and labor-intensive. Embryos are often designated into stage ranges, making the information on developmental time course. This makes downstream analyses inefficient and biological interpretations of similarities and differences in spatial expression patterns challenging, particularly when using automated tools for analyzing expression patterns of large number of images. Results: Here, we present a new computational approach to annotate developmental stage for Drosophila embryos in the gene expression images. In an analysis of 3724 images, the new approach shows high accuracy in predicting the developmental stage correctly (79%). In addition, it provides a stage score that enables one to more finely annotate each embryo so that they are divided into early and late periods of development within standard stage demarcations. Stage scores for all images containing expression patterns of the same gene enable a direct way to view expression changes over developmental time for any gene. We show that the genomewide-expression-maps generated using images from embryos in refined stages illuminate global gene activities and changes much better, and more refined stage annotations improve our ability to better interpret results when expression pattern matches are discovered between genes. Availability and implementation: The software package is available for download at: http://www.public.asu.edu/?jye02/Software/Fly-Project/. Contact: jieping.ye@asu.edu Supplementary information: Supplementary data are available at Bioinformatics online.

Yuan, Lei; Pan, Cheng; Ji, Shuiwang; McCutchan, Michael; Zhou, Zhi-Hua; Newfeld, Stuart J.; Kumar, Sudhir; Ye, Jieping

2014-01-01

355

Effect of Clouds on Optical Imaging of the Space Shuttle During the Ascent Phase: A Statistical Analysis Based on a 3D Model  

NASA Technical Reports Server (NTRS)

Clouds are highly effective in obscuring optical images of the Space Shuttle taken during its ascent by ground-based and airborne tracking cameras. Because the imagery is used for quick-look and post-flight engineering analysis, the Columbia Accident Investigation Board (CAIB) recommended the return-to-flight effort include an upgrade of the imaging system to enable it to obtain at least three useful views of the Shuttle from lift-off to at least solid rocket booster (SRB) separation (NASA 2003). The lifetimes of individual cloud elements capable of obscuring optical views of the Shuttle are typically 20 minutes or less. Therefore, accurately observing and forecasting cloud obscuration over an extended network of cameras poses an unprecedented challenge for the current state of observational and modeling techniques. In addition, even the best numerical simulations based on real observations will never reach "truth." In order to quantify the risk that clouds would obscure optical imagery of the Shuttle, a 3D model to calculate probabilistic risk was developed. The model was used to estimate the ability of a network of optical imaging cameras to obtain at least N simultaneous views of the Shuttle from lift-off to SRB separation in the presence of an idealized, randomized cloud field.

Short, David A.; Lane, Robert E., Jr.; Winters, Katherine A.; Madura, John T.

2004-01-01

356

Cloud computing for geophysical applications (Invited)  

NASA Astrophysics Data System (ADS)

Cloud computing offers a scalable on-demand resource allocation model to evolving needs in data intensive geophysical applications, where computational needs in CPU and storage can vary over time depending on modeling or field campaign. Separate, sometimes incompatible cloud platforms and services are already available from major computing vendors (Amazon AWS, Microsoft Azure, Google Apps Engine), government agencies (NASA Nebulae) and Open Source community (Eucalyptus). Multiple cloud platforms with layered virtualization patterns (hardware-platform- software-data-or-everything as a service) provide a feature-rich environment and encourage experimentation with distributed data modeling, processing and storage. However, application and especially database development in the Cloud is different from the desktop and the compute cluster. In this presentation we will review scientific cloud applications relevant to geophysical research and present our results in building software components and cloud services for a virtual geophysical data center. We will discuss in depth economy, scalability and reliability of the distributed array and image data stores, synchronous and asynchronous RESTful services to access and model georefernced data, virtual observatory services for metadata management, and data visualization for web applications in Cloud.

Zhizhin, M.; Kihn, E. A.; Mishin, D.; Medvedev, D.; Weigel, R. S.

2010-12-01

357

Focussing on the future: Survey results on the image capture of patterned cutaneous injuries.  

PubMed

An investigator who is involved in assessing the likelihood of physical abuse must make a decision as to whether the injury seen matches the explanation given. In some instances the pattern of these injuries can give the investigator a possible link to the cause of the injury. Photographic imaging is used to record the patterned cutaneous injuries (PCI) and to facilitate forensic interpretation. The current method of capturing PCI often results in some form of distortion that causes a change to the shape of the patterned injury. The Dermatological Patterned Injury Capture and Analysis (DePICA) research group was formed to assess current image capture methods and practices. An online survey was set up to assess the value of localised imaging protocols and training specific to imaging PCI and was made available to law enforcement professionals, forensic investigators and hospital staff. 80 participants responded to the survey. The majority of the survey participants have had training in medical or forensic photography, however 66 (83%) have not had specific training in how to photograph PCI. 41 (51%) of the participants responded that they always use a rigid scale and 34 (43%) position the camera so that it is perpendicular to the scale and injury. Comments made about the quality of images obtained and produced raises concerns about how much knowledge those initiating such images have about image relevance in criminal cases. It is evident that a clear and comprehensive guide to photographing PCIs is required to improve the quality of the photographic evidence that is collected. PMID:24794842

Evans, Sam; Baylis, Sonya; Carabott, Romina; Jones, Michael; Lawson, Zoe; Marsh, Nick; Payne-James, Jason; Ramadani, Jona; Vanezis, Peter; Kemp, Alison

2014-05-01

358

Efficient and effective extraction of vocal fold vibratory patterns from high-speed digital imaging  

PubMed Central

Objectives High-speed digital imaging can provide valuable information on disordered voice production in voice science. However, the large amounts of high-speed image data with limited image resolutions produce significant challenges for computer analysis, and thus effective and efficient image edge extraction methods allowing for the batch analysis of high-speed images of vocal folds is clinically important. In this paper, a novel algorithm for automatic image edge detection is proposed to effectively and efficiently process high-speed images of the vocal folds. Methods The method integrates Lagrange interpolation, differentiation, and Canny edge detection, which allow objective extraction of aperiodic vocal fold vibratory patterns from large numbers of high-speed digital images. This method and two other popular algorithms, histogram and active contour, are performed on 10 sets of high-speed video data from excised larynx experiments in order to compare their performances in analyzing high-speed images. The accuracy in computing glottal area and the computation time of these methods are investigated. Results and Discussion The results show that our proposed method provides the most accurate and efficient detection, and is applicable when processing low resolution images. In this study, we focus on developing a method to effectively and efficiently process high-speed image data from excised larynges. However in addition we show the clinical potential of this method by use of example high-speed image data obtained from a patient with vocal nodules. Conclusions The proposed automatic image-processing algorithm may provide a valuable biomedical application for the clinical assessment of vocal disorders by use of high-speed digital imaging.

Zhang, Yu; Bieging, Erik; Tsui, Henry; Jiang, Jack J.

2010-01-01

359

Laser point cloud diluting and refined 3D reconstruction fusing with digital images  

Microsoft Academic Search

This paper shows a method to combine the imaged-based modeling technique and Laser scanning data to rebuild a realistic 3D model. Firstly use the image pair to build a relative 3D model of the object, and then register the relative model to the Laser coordinate system. Project the Laser points to one of the images and extract the feature lines

Jie Liu; Jianqing Zhang

2007-01-01

360

Spatial Pattern Analysis of Functional Brain Images Using Partial Least Squares  

Microsoft Academic Search

This paper introduces a new tool for functional neuroimage analysis: partial least squares (PLS). It is unique as a multivariate method in its choice of emphasis for analysis, that being the covariance between brain images and exogenous blocks representing either the experiment design or some behavioral measure. What emerges are spatial patterns of brain activity that represent the optimal association

A. R. McIntosh; F. L. Bookstein; J. V. Haxby; C. L. Grady

1996-01-01

361

Object-based algorithms and methods for quantifying urban growth pattern using sequential satellite images  

NASA Astrophysics Data System (ADS)

Previously, urban growth pattern is described and measured by the pixel-by-pixel comparison of satellite images. The geographic extent, patterns and types of urban growth are derived from satellite images separated in time. However, the pixel-by-pixel comparison approach suffers from several drawbacks. Firstly, slight error in image geo-reference can cause false detection of changes. Secondly, it's difficult to recognize and correct artifact changes induced by data noise and data processing errors. Thirdly, only limited information can be derived. In this paper, we present a new objectbased method to describe and quantify urban growth patterns. The different types of land cover are classified from sequential satellite images as urban objects. The geometric and shape attributes of objects and the spatial relationship between them are employed to identify the different types of urban growth pattern. The algorithms involved in the object-based method are implemented by using C++ programming language and the software user interface is developed by using ArcObjects and VB.Net. A simulated example is given to demonstrate the utility and effectiveness of this new method.

Yu, Bailang; Liu, Hongxing; Gao, Yige; Wu, Jianping

2008-08-01

362

Patterned interrogation scheme for compressed sensing photoacoustic imaging using a Fabry Perot planar sensor  

NASA Astrophysics Data System (ADS)

Photoacoustic tomography (PAT) has become a powerful tool for biomedical imaging, particularly pre-clinical small animal imaging. Several different measurement systems have been demonstrated, in particular, optically addressed Fabry-Perot interferometer (FPI) sensors have been shown to provide exquisite images when a planar geometry is suitable. However, in its current incarnation the measurements must be made at each point sequentially, so these devices therefore suffer from slow data acquisition time. An alternative to this point-by-point interrogation scheme, is to interrogate the whole sensor with a series of independent patterns, so each measurement is the spatial integral of the product of the pattern and the acoustic field (as in the single-pixel Rice camera). Such an interrogation scheme allows compressed sensing to be used. This enables the number of measurements to be reduced significantly, leading to much faster data acquisition. An experimental implementation will be described, which employs a wide NIR tunable laser beam to interrogate the FPI sensor. The reflected beam is patterned by a digital micro-mirror device, and then focused to a single photodiode. To demonstrate the idea of patterned and compressed sensing for ultrasound detection, a scrambled Hadamard operator is used in the experiments. Photoacoustic imaging experiments of phantoms shows good reconstructed results with 20% compression.

Huynh, Nam; Zhang, Edward; Betcke, Marta; Arridge, Simon; Beard, Paul; Cox, Ben

2014-03-01

363

Impact of across-pupil transmittance variation in projection lenses on fine device pattern imaging  

Microsoft Academic Search

Transmittance of projection lenses used in DUV exposure tools changes depending on the exposure light path. We studied the impact of this phenomenon (Across Pupil Transmittance Variation, APTV) on fine device pattern imaging. Zernike polynomials, which are commonly used for analysis of wavefront aberration, were applied for inspecting the influence of APTV. We investigated influences of each Zernike component on

Kazuya Sato; Shoji Mimotogi; Soichi Inoue; Tatsuhiko Higashiki

2003-01-01

364

On Images and Fraunhofer Diffraction Patterns Obtained from Fresnel Zone Plates  

Microsoft Academic Search

A Fourier-series representation of a Fresnel zone plate is set up and used, with a paraxial approximation, to predict features of the image-forming and Fourier-transforming properties of the plate. These properties are compared and contrasted with those of a lens, and examples of a Fraunhofer diffraction pattern from a plate and a lens are illustrated.

G. Harburn; R. P. Williams

1975-01-01

365

Fixed pattern noise suppression by a differential readout chain for a radiation tolerant image sensor  

Microsoft Academic Search

This article discusses a circuit to suppress fixed pattern noise in CMOS active pixel sensors, and its implementation in a radiation tolerant image sensor. This technique is based upon the readout of both the signal level and the reset level of the pixel through exactly the same signal path. The need for multiplexing of signals at a speed higher than

Guy Meynants; Bart Dierickx; Dirk Uwaerts; Jan Bogaerts

366

Full-field measurements of heterogeneous deformation patterns on polymeric foams using digital image correlation  

Microsoft Academic Search

The ability of a digital image correlation technique to capture the heterogeneous deformation fields appearing during compression of ultra-light open-cell foams is presented in this article. Quantitative characterization of these fields is of importance to understand the mechanical properties of the collapse process and the energy dissipation patterns in this type of materials. The present algorithm is formulated in the

Yu Wang; Alberto M Cuitiño

2002-01-01

367

Reliability of an Image Analysis System for Quantifying the Radiographic Trabecular Pattern  

Microsoft Academic Search

A reliability evaluation technique was used to examine the reliability of an image analysis system of the trabecular pattern and to determine the contribution of three possible sources of error variance. Two series of radiographs were taken of 14 lumbar vertebral slices (28 radiographs). Every radiograph was placed on a viewing box for digitization four times by a single operator

Clara M. Korstjens; Rob J. Spruijt; Wil G. M. Geraets; Lis Mosekilde; Paul F. Van Der Stelt

1997-01-01

368

Hyperspectral simulation of chemical weapon dispersal patterns using DIRSIG  

NASA Astrophysics Data System (ADS)

Fieldable thermal infrared hyperspectral imaging spectrometers has made it possible to design and construct new instruments for better detection of battlefield hazards such as chemical weapon clouds. The availability of spectroscopic measurements of these clouds can be used not only for the detection and identification of specific chemical agents but also to potentially quantify the lethality of the cloud. The simulation of chemical weapon dispersal patterns in a synthetic imaging environment offers significant benefits to sensor designers. Such an environment allows designers to easily develop trade spaces to test detection and quantification algorithms without the need for expensive and dangerous field releases. This paper discusses the implementation of a generic gas dispersion model that has been integrated into the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model. The gas cloud model utilizes a 3D Gaussian distribution and first order dynamics (drift and dispersion) to drive the macro-scale cloud development and movement. The model also attempts to account for turbulence by incorporating fractional Brownian motion techniques to reproduce the micro-scale variances within the cloud. The cloud path length concentrations are then processed by the DIRSIG radiometry sub-model to compute the emission and transmission of the cloud body on a per-pixel basis. Example hyperspectral image cubes containing common agents and release amounts will be presented. Time lapse sequences will also be presented to demonstrate the evolution of the cloud over time.

Arnold, Peter S.; Brown, Scott D.; Schott, John R.

2000-07-01

369

Exploiting adaptive total variation model for image reconstruction from speckle patterns  

NASA Astrophysics Data System (ADS)

Due to the multiple scattering of light in turbid media such as biological tissues, the image of target becomes highly deteriorated even disappears entirely. The adaptive total variation (ATV) image reconstruction algorithm, which is based on majorization-minimization approach together with Bayesian framework, is utilized to recover the object from its speckle pattern. Numerical simulation results indicates that, compared with Tikhonov regularization method, the ATV approach can effectively suppress the noise of the restored image and preserve more image details as well, consequently greatly boosts the SNR and the sharpness of the result image. Furthermore, the recovered results by ATV algorithm have overcome the diffraction-limit of the conventional optical system. Consequently, the combination of ATV algorithm with multiple scattering of turbid media will be beneficial to the observation of cells and protein molecules in biological tissues and other structures in micro/nano scale.

Gong, Changmei; Shao, Xiaopeng; Wu, Tengfei

2013-08-01

370

Cloud model-based Bayesian technique for precipitation profile retrieval from the Tropical Rainfall Measuring Mission Microwave Imager  

NASA Astrophysics Data System (ADS)

A cloud model-based statistical retrieval technique for estimating surface precipitation and cloud profiles over ocean, called Bayesian Algorithm for Microwave Precipitation Retrieval (BAMPR), is described. The inversion scheme, based on the Bayesian estimation theory, is trained by a CRD obtained by inputting the numerical outputs of a mesoscale microphysical model into a three-dimensional radiative transfer model. Since the performances of the retrieval are strictly dependent on the a priori information given by the CRD, the generation of the database itself, and the coupling between the forward and the inverse problem are carefully discussed. Particular emphasis is given to the database representativeness of the meteorological event under investigation and to the quantification of modeling errors. The retrieval uncertainties are provided with the estimates themselves by choosing the Minimum Mean Square technique as a Bayesian inversion method. As an example, the algorithm is applied to some case studies in the Tropics using the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager data. The analysis is focused on the evaluation of the CRD performances with respect to the various events (i.e., a tropical cyclone, a tropical storm, a summer front, and some isolated convective cells in the Atolls region) and different CRDs (i.e., two hurricanes from the University of Wisconsin Nonhydrostatic Modeling System and a tropical squall line from the Goddard Cumulus Ensemble model). A detailed examination is carried out on the case of the hurricane Bonnie on 25 August 1998, which is discussed by using TRMM official products as a comparison.

Tassa, Alessandra; di Michele, Sabatino; Mugnai, Alberto; Marzano, Frank S.; Poiares Baptista, José Pedro V.

2003-08-01

371

Voyager 1 imaging and IRIS observations of Jovian methane absorption and thermal emission: Implications for cloud structure  

NASA Technical Reports Server (NTRS)

Images from three filters of the Voyager 1 wide angle camera are used to measure the continuum reflectivity and spectral gradient near 6000 A and the 6190 A band methane/continuum ratio for a variety of cloud features in Jupiter's atmosphere. The dark barge features in the North Equatorial Belt have anomalously strong positive continuum spectral gradients suggesting unique composition. Methane absorption is shown at unprecedented spatial scales for the Great Red Spot and its immediate environment, for a dark barge feature in the North Equatorial Belt, and for two hot spot and plume regions in the North Equatorial Belt. Methane absorption and five micrometer emission are correlated in the vicinity of the Great Red Spot but are anticorrelated in one of the plume hot spot regions. Methane absorption and simultaneous maps of five micrometer brightness temperature is quantitatively compared to realistic cloud structure models which include multiple scattering at five micrometer as well as in the visible. Variability in H2 quadrupole lines are also investigated.

West, R. A.; Kupferman, P. N.; Hart, H.

1984-01-01

372

Teaching image processing and pattern recognition with the Intel OpenCV library  

NASA Astrophysics Data System (ADS)

In this paper we present an approach to teaching image processing and pattern recognition with the use of the OpenCV library. Image processing, pattern recognition and computer vision are important branches of science and apply to tasks ranging from critical, involving medical diagnostics, to everyday tasks including art and entertainment purposes. It is therefore crucial to provide students of image processing and pattern recognition with the most up-to-date solutions available. In the Institute of Electronics at the Technical University of Lodz we facilitate the teaching process in this subject with the OpenCV library, which is an open-source set of classes, functions and procedures that can be used in programming efficient and innovative algorithms for various purposes. The topics of student projects completed with the help of the OpenCV library range from automatic correction of image quality parameters or creation of panoramic images from video to pedestrian tracking in surveillance camera video sequences or head-movement-based mouse cursor control for the motorically impaired.

Koz?owski, Adam; Królak, Aleksandra

2009-06-01

373

Fine pixel SEM image for EUV mask pattern 3D quality assurance based on lithography simulation  

NASA Astrophysics Data System (ADS)

Optical proximity correction (OPC) is still an essential technology for critical dimension (CD) control in Extreme Ultra Violet (EUV) lithography. For quality assurance of EUV mask pattern, a metrology of complicated two-dimensional (2D) OPC patterns is important. Moreover, the side wall angle management of a mask pattern becomes important in EUV lithography because exposure light is diagonally incident on a mask pattern. The quality assurance of EUV mask pattern requires the pattern edge extraction including the side wall angle. We had developed an SEM which is one of the key factors of this three-dimensional (3D) quality assurance method. The high accuracy measurement of a side wall angle using Tilting and Moving Objective Lens (T-MOL) is most feature of this SEM. Employing this SEM, we will add the side wall angle information to the system for guaranteeing 2D OPC patterns before shipping the mask to a wafer factory. In this paper, we report the study about the management of the side wall angle of an EUV mask pattern. And then we report the evaluation results of the side wall angle measurement system with a tilted fine pixel SEM image that satisfies the requirement of the management.

Yamanaka, Eiji; Itoh, Masamitsu; Kato, Masaya; Ueno, Kusuo; Hayashi, Kyouhei; Higuchi, Akira; Hayashi, Naoya

2010-04-01

374

Luminance and image quality analysis of an organic electroluminescent panel with a patterned microlens array attachment  

NASA Astrophysics Data System (ADS)

Luminance and image quality observed from the normal direction of a commercial 2.0 inch panel based on organic electroluminescence (OEL) technology attached to regular and patterned microlens array films (MAFs) were studied and analyzed. When applying the regularly arranged MAF on the panel, a luminance enhancement of 23% was observed, accompanied by a reduction of the image quality index as low as 74%. By removing the microlenses on the emitting areas, the patterned MAF enhances the luminance efficiency of the OEL by 52% keeping the image quality index of the display as high as 94%, due to the effective light extraction in the glass substrate being less than the critical angle. 3D simulation based on a ray-tracing model was also established to investigate the spatial distribution of light rays radiated from an OEL pixel with different microstructures which showed consistent results with the experimental results.

Lin, Hoang Yan; Chen, Kuan-Yu; Ho, Yu-Hsuan; Fang, Jheng-Hao; Hsu, Sheng-Chih; Lin, Jia-Rong; Lee, Jiun-Haw; Wei, Mao-Kuo

2010-08-01

375

Cloud shortwave spectral transmittance: Applications in remote sensing and aerosol-cloud interactions  

NASA Astrophysics Data System (ADS)

A long record of cloud optical thickness and effective particle radius retrieved from cloud reflectance exists with no comparable dataset retrieved from cloud transmittance. This is due to a lack of sensitivity to the effective radius in cloud transmittance. A new algorithm that uses spectrally resolved cloud transmittance observations to retrieve optical thickness and effective radius is presented. The algorithm relies on the spectral slope of the normalized transmittance between 1565 nm and 1634 nm and on cloud transmittance at a visible wavelength. Using the spectral slope rather than the transmittance itself enhances the sensitivity of transmittance observations with respect to the effective radius. This is demonstrated by applying the algorithm to hyperspectral data from two field sites. The liquid water path is derived and compared to the simultaneous observations from a microwave radiometer and the optical thickness and effective radius are compared to MODIS retrievals. The algorithm was applied to ship-based observations in another field campaign, CalNex, which featured a day, 16 May 2010, of coordinated observations from a research ship and aircraft, providing the opportunity to compare retrievals from surface-based radiometers, an airborne radiometer, a satellite imager, and in-situ cloud probes. A statistical look at the cloud properties is presented and compared to previous studies. The retrievals and cloud transmittance are used to make observations of cloud transmittance susceptibility for the first time. Cloud transmittance susceptibility quantifies the change in cloud transmittance for a change in cloud droplet number concentration, thereby representing a possible change in cloud transmittance due to a change in aerosol burden. The results of the two initial case studies showed that, in general, the effective radius uncertainties were much larger for the standard retrieval than for the spectral retrieval, particularly for thin clouds. When defining 2 ?m as upper limit for the tolerable uncertainty of the effective radius, the standard method returned only very few valid retrievals for douds with an optical thickness below 25. At one field site (mean optical thickness 23), the spectral method provided valid retrievals for 84% of the data (24% for the standard method). At the other (mean optical thickness 44), both methods provided a high return of 90% for the spectral method and 78% for the standard method. The CalNex comparisons for 16 May 2010 showed that the agreement between the retrievals increased as the difference between the sampling volumes of the instruments decreased. The average in-situ reff (7.7 ?m) fell between the average reff retrieved using the Atlantis-based SSFR radiance (5. 7 ?m) and irradiance (9.5 ?m). The statistical study of all clouds during CalNex showed a diurnal pattern observed in previous studies of marine boundary layer clouds. The climatology of cloud optical thickness and liquid water path was shown to be represented by a gamma distribution, consistent with previous studies of high cloud fraction marine boundary layer clouds. Model calculations of transmittance susceptibility showed that clouds are more susceptible as effective radius increases and less susceptible as optical thickness increases. The observations of cloud transmittance susceptibility show that the clouds encountered during CaiN ex were not highly susceptible. Comparisons to previous studies of cloud reflectance susceptibility also show this. Comparisons of observations in northern California and southern California show that the least susceptible clouds were in the south, where aerosol concentrations were higher at the surface, effective radius was smaller, optical thickness was larger than the observations in the north.

McBride, Patrick J.

376

Multiline spectral imaging of dense cores in the Lupus molecular cloud  

Microsoft Academic Search

The molecular clouds Lupus 1, 3 and 4 were mapped with the Mopra Telescope at 3 and 12 mm. Emission lines from high-density molecular tracers were detected, i.e. NH3 (1,1), NH3 (2,2), N2H+ (1-0), HC3N (3-2), HC3N (10-9), CS (2-1), CH3OH (20-10)A+ and CH3OH (2-1-1-1)E. Velocity gradients of more than 1 km s-1 are present in Lupus 1 and 3,

M. Benedettini; S. Pezzuto; M. G. Burton; S. Viti; S. Molinari; P. Caselli; L. Testi

2012-01-01

377

An Approach to Improve the Quality of Infrared Images of Vein-Patterns  

PubMed Central

This study develops an approach to improve the quality of infrared (IR) images of vein-patterns, which usually have noise, low contrast, low brightness and small objects of interest, thus requiring preprocessing to improve their quality. The main characteristics of the proposed approach are that no prior knowledge about the IR image is necessary and no parameters must be preset. Two main goals are sought: impulse noise reduction and adaptive contrast enhancement technologies. In our study, a fast median-based filter (FMBF) is developed as a noise reduction method. It is based on an IR imaging mechanism to detect the noisy pixels and on a modified median-based filter to remove the noisy pixels in IR images. FMBF has the advantage of a low computation load. In addition, FMBF can retain reasonably good edges and texture information when the size of the filter window increases. The most important advantage is that the peak signal-to-noise ratio (PSNR) caused by FMBF is higher than the PSNR caused by the median filter. A hybrid cumulative histogram equalization (HCHE) is proposed for adaptive contrast enhancement. HCHE can automatically generate a hybrid cumulative histogram (HCH) based on two different pieces of information about the image histogram. HCHE can improve the enhancement effect on hot objects rather than background. The experimental results are addressed and demonstrate that the proposed approach is feasible for use as an effective and adaptive process for enhancing the quality of IR vein-pattern images.

Lin, Chih-Lung

2011-01-01

378

Automated cloud detection and classification of data collected by the Visible Infrared Imager Radiometer Suite (VIIRS)  

Microsoft Academic Search

The Visible Infrared Imager Radiometer Suite (VIIRS) is a high?resolution Earth imager of the United States National Polar?orbiting Operational Environmental Satellite System (NPOESS). VIIRS has its heritage in three sensors currently collecting imagery of the Earth—the Advanced Very High Resolution Radiometer, the Moderate Resolution Imaging Spectroradiometer, and the Operational Linescan Sensor. The first launch of the VIIRS sensor is on

K. D. Hutchison; J. K. Roskovensky; J. M. Jackson; A. K. Heidinger; T. J. Kopp; M. J. Pavolonis; R. Frey

2005-01-01

379

A local-sky star recognition algorithm based on rapid triangle pattern index for ICCD images  

NASA Astrophysics Data System (ADS)

Local-sky star recognition algorithm is a process of recognizing the extracted stars in image by making use of the prior rough attitude of star sensor in celestial sphere. In order to improve the detection and response performance of star sensor working in dynamic condition, ICCD is applied to imaging stars. However, image taken by ICCD has more non-Gaussian noise and the energy of imaging star is unstable. So a local-sky star recognition algorithm using spatial triangular relationship as matching features is supposed to deal with the difficulties. In the first place, an index array is designed according to Guide Triangles, which is applied to construct Guide Triangle Index List. In the second place, a general directing range of star sensor boresight is calculated according to FOV of star sensor and the output of inertial guidance system, and then, the candidate Guide Triangles set in above region is obtained rapidly. In the third place, construct image triangle patterns by applying position and energy of the extracted stars in the image, and then match the image triangle patterns with the above candidate Guide Triangles set for two stages, until N(N>=2) groups of successfully matched triangles pairs with smallest matching deviations sum are obtained. At the last, the recognized Guide Stars have to be matched posterior referring to the principle of simulated sky image, and the recognition results of image stars are all obtained. The proposed algorithm has compact Guide Database structure, rapid local-sky guide triangles obtaining, and good recognition correction percentage, even it has worse star location precision and more false stars. The simulation tests are performed to validate the relative efficiency and adaptation of the algorithm.

Zhang, Wei; Qi, Sheng-xiang; Zhang, Rui; Yang, Lili; Sun, Ji-fu; Song, Li-quan; Tian, Jin-wen

2013-09-01

380

Mapping of SO2 on Venus within the H2SO4 cloud using ground-based infrared imaging spectroscopy  

NASA Astrophysics Data System (ADS)

Sulfur dioxide and water vapor, two key parameters of Venus' photochemistry, are known to exhibit significant spatial and temporal variations. In particular, ground-based thermal imaging spectroscopy at high resolution, achieved on Venus in January 2012, has shown evidence for strong SO2 variations on timescales shorter than a day (Encrenaz et al. AA 543, 153, 2012). We have continued our observing campaign using the TEXES high-resolution imaging spectrometer at the NASA Infrared Telescope Facility to map sulfur dioxide over the disk of Venus at two different wavelengths, 7 ?m (already used in the previous study) and 19 ?m. The 7 ?m radiation probes the top of the H2SO4 cloud at about 65 km, while the 19 ?m radiation probes at deeper levels within the cloud. Observations took place on October 4 and 5, 2012. The diameter of Venus was 15 arcsec, with an illumination factor of 72%. Data were recorded at 1343-1353 cm-1 during the two first hours of each run and at 529-531 cm-1 during the two last hours. The spectral resolving power and spatial resolution were, respectively, about 70000 and 1 arcsec at 7 ?m, and 60000 and 1.5 arcsec at 19 ?m. The Doppler velocity of Venus was + 12 km/s, corresponding to a Doppler shift of - 0.054 cm-1 at 1350 cm-1 and - 0.021 cm-1 at 530 cm-1. Both HDO and SO2 lines are identified in our 7 ?m spectra and SO2 is also easily identified at 19 ?m; the poor weather and the high water atmospheric content during our observing run limited the quality of the 7 ?m observations. As observed in our previous run, the HDO map is relatively uniform over the disk of Venus. In contrast, the SO2 maps at 19 ?m show intensity variations over the disk, as observed in January 2012 at 7 ?m. In addition, the SO2 map at 19 ?m shows significant changes within a timescale of an hour. The CO2 lines at 7 and 19 ?m will be used to infer the thermal structure within the cloud and to study its latitudinal variations.

Encrenaz, Therese; Greathouse, Thomas; Richter, Matthew; Lacy, John; Bézard, Bruno; Fouchet, Thierry; DeWitt, Curtis; Widemann, Thomas

2013-04-01

381

Waves on White: Ice or Clouds?  

NASA Technical Reports Server (NTRS)

As it passed over Antarctica on December 16, 2004, the Multi-angle Imaging SpectroRadiometer (MISR) on NASA's Terra satellite captured this image showing a wavy pattern in a field of white. At most other latitudes, such wavy patterns would likely indicate stratus or stratocumulus clouds. MISR, however, saw something different. By using information from several of its multiple cameras (each of which views the Earth's surface from a different angle), MISR was able to tell that what looked like a wavy cloud pattern was actually a wavy pattern on the ice surface. One of MISR's cloud classification products, the Angular Signature Cloud Mask (ASCM), correctly identified the rippled area as being at the surface.

In this image pair, the view from MISR's most oblique backward-viewing camera is on the left, and the color-coded image on the right shows the results of the ASCM. The colors represent the level of certainty in the classification. Areas that were classed as cloudy with high confidence are white, and areas where the confidence was lower are yellow; dark blue shows confidently clear areas, while light blue indicates clear with lower confidence. The ASCM works particularly well at detecting clouds over snow and ice, but also works well over ocean and land. The rippled area on the surface which could have been mistaken for clouds are actually sastrugi -- long wavelike ridges of snow formed by the wind and found on the polar plains. Usually sastrugi are only several centimeters high and several meters apart, but large portions of East Antarctica are covered by mega-sastrugi ice fields, with dune-like features as high as four meters separated by two to five kilometers. The mega-sastrugi fields are a result of unusual snow accumulation and redistribution processes influenced by the prevailing winds and climate conditions. MISR imagery indicates that these mega sastrugi were stationary features between 2002 and 2004.

Being able to distinguish clouds from snow or ice-covered surfaces is important in order to adequately characterize the radiation balance of the polar regions. However, detecting clouds using spaceborne detectors over snow and ice surfaces is notoriously difficult, because the surface may often be as bright and as cold as the overlying clouds, and because polar atmospheric temperature inversions sometimes mean that clouds are warmer than the underlying snow or ice surface. The Angular Signature Cloud Mask (ASCM) was developed based on the Band-Differenced Angular Signature (BDAS) approach, introduced by Di Girolamo and Davies (1994) and updated for MISR application by Di Girolamo and Wilson (2003). BDAS uses both spectral and angular changes in reflectivity to distinguish clouds from the background, and the ASCM calculates the difference between the 446 and 866 nanometer reflectances at MISR's two most oblique cameras that view forward-scattered light. New land thresholds for the ASCM are planned for delivery later this year.

The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously and every 9 days views the entire globe between 82o north and 82o south latitude. This image area covers about 277 kilometers by 421 kilometers in the interior of the East Antarctic ice sheet. These data products were generated from a portion of the imagery acquired during Terra orbit 26584 and utilize data from within blocks 159 to 161 within World Reference System-2 path 63.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

2005-01-01

382

Mean intensity gradient: An effective global parameter for quality assessment of the speckle patterns used in digital image correlation  

Microsoft Academic Search

Digital image correlation (DIC) is an image-based optical metrology for full-field deformation measurement. In DIC technique, the test object surface must be covered with a random speckle pattern, which deforms together with the object surface as a carrier of deformation information. In practice, the speckle patterns may show distinctly different intensity distribution characteristics and have an important influence on DIC

Bing Pan; Zixing Lu; Huimin Xie

2010-01-01

383

Local tetra patterns: a new feature descriptor for content-based image retrieval.  

PubMed

In this paper, we propose a novel image indexing and retrieval algorithm using local tetra patterns (LTrPs) for content-based image retrieval (CBIR). The standard local binary pattern (LBP) and local ternary pattern (LTP) encode the relationship between the referenced pixel and its surrounding neighbors by computing gray-level difference. The proposed method encodes the relationship between the referenced pixel and its neighbors, based on the directions that are calculated using the first-order derivatives in vertical and horizontal directions. In addition, we propose a generic strategy to compute nth-order LTrP using (n - 1)th-order horizontal and vertical derivatives for efficient CBIR and analyze the effectiveness of our proposed algorithm by combining it with the Gabor transform. The performance of the proposed method is compared with the LBP, the local derivative patterns, and the LTP based on the results obtained using benchmark image databases viz., Corel 1000 database (DB1), Brodatz texture database (DB2), and MIT VisTex database (DB3). Performance analysis shows that the proposed method improves the retrieval result from 70.34%/44.9% to 75.9%/48.7% in terms of average precision/average recall on database DB1, and from 79.97% to 85.30% and 82.23% to 90.02% in terms of average retrieval rate on databases DB2 and DB3, respectively, as compared with the standard LBP. PMID:22514130

Murala, Subrahmanyam; Maheshwari, R P; Balasubramanian, R

2012-05-01

384

Jupiter's High-Altitude Clouds  

NASA Technical Reports Server (NTRS)

The New Horizons Multispectral Visible Imaging Camera (MVIC) snapped this incredibly detailed picture of Jupiter's high-altitude clouds starting at 06:00 Universal Time on February 28, 2007, when the spacecraft was only 2.3 million kilometers (1.4 million miles) from the solar system's largest planet. Features as small as 50 kilometers (30 miles) are visible. The image was taken through a narrow filter centered on a methane absorption band near 890 nanometers, a considerably redder wavelength than what the eye can see. Images taken through this filter preferentially pick out clouds that are relatively high in the sky of this gas giant planet because sunlight at the wavelengths transmitted by the filter is completely absorbed by the methane gas that permeates Jupiter's atmosphere before it can reach the lower clouds.

The image reveals a range of diverse features. The south pole is capped with a haze of small particles probably created by the precipitation of charged particles into the polar regions during auroral activity. Just north of the cap is a well-formed anticyclonic vortex with rising white thunderheads at its core. Slightly north of the vortex are the tendrils of some rather disorganized storms and more pinpoint-like thunderheads. The dark 'measles' that appear a bit farther north are actually cloud-free regions where light is completely absorbed by the methane gas and essentially disappears from view. The wind action considerably picks up in the equatorial regions where giant plumes are stretched into a long wave pattern. Proceeding north of the equator, cirrus-like clouds are shredded by winds reaching speeds of up to 400 miles per hour, and more pinpoint-like thunderheads are visible. Although some of the famous belt and zone structure of Jupiter's atmosphere is washed out when viewed at this wavelength, the relatively thin North Temperate Belt shows up quite nicely, as does a series of waves just north of the belt. The north polar region of Jupiter in this image has a mottled appearance, and the scene is not as dynamic as the equatorial and south polar regions.

The intricate structures revealed in this image are exciting, but they are only part of the story. The New Horizons instruments have taken images of Jupiter at approximately 260 different wavelengths, providing essentially a three-dimensional view of Jupiter's atmosphere, since images at different wavelengths probe different altitudes. New Horizons is providing a wealth of data on this fascinating planet during this last close-up view of Jupiter until the middle of the next decade.

2007-01-01

385

3D city site model extraction through point cloud generated from stereo images  

Microsoft Academic Search

It is a grand challenge to automatically extract 3D city site models from imagery. In the past three decades, researchers have used radiometric and spectral properties of 3D buildings and houses to extract them in digital imagery with limited success. This is because their radiometric and spectral properties vary considerably from image to image, from sensor to sensor, and from

Bingcai Zhang; William Smith

2011-01-01

386

Deep near-infrared and optical imaging photometry of the Serpens cloud core  

NASA Astrophysics Data System (ADS)

Knowledge of the distribution of young stars within molecular clouds is of fundamental importance since it provides insights into the nature of star-forming mechanisms. Young Stellar objects (YSOs) are associated with varying amounts of gas and dust and it is expected that the youngest objects will be invisible at optical wavelengths due to obscuration of opaque circumstellar dust. Therefore observations at infrared wavelengths provide one of the best method for identifying the young stellar population within molecular clouds. Clusters are important laboratories for studying the initial luminosity function because they consist of statistically significant groups of stars who share the common heritage of forming from the same parental cloud and they are not old enough to have lost significant number of members due to stellar evolution or dynamical effects such as evaporation or violent relaxation. Moreover in these very young clusters (a few x 10^6 yrs), low-mass stars are brighter than at any other time in their Pre-Main Sequence (PMS) evolution. The Serpens molecular cloud is one of the most spectacular example of a protostellar nursery, harboring a stellar density exceeding 450 stars pc^{-3} (Eiroa and Casali 1992). At a distance of 310 pc (de Lara et al. 1991), recent near-infrared and submillimeter continuum surveys of the region have uncovered over half-dozen mm/submillimeter peaks among the more than fifty low-mass stars identified in the core, most of which lack near-infrared counterparts (Casali et al. 1993, White et al. 1995). This region have received considerable attention since Strom et al. (1974) drew attention to a small red nebulosity, often called the Serpens Object or the Serpens Reflection Nebula (SRN). A low resolution CO and H_2CO survey revealed a dense core in the dark cloud complex (Loren et al. 1979). More recently, Hurt and Barsony (1996) found several sources sharing the defining characteristics of Class 0 protostars, the short-lived (a few x 10^4 yrs) earliest protostellar stage. In this poster we present new deep optical and near-infrared observations of the Serpens cloud core using array detectors. We estimate our completeness limits to be 24, 23, 23, 19, 18.5 and 17.0 at V, R, I, J, H and K respectively, although sources as faint as K=17.6 were detected. We surveyed an area of 4'x4.8' centered approximately on the Serpens Reflexion Nebula at alpha(1950)=18h27m24s and delta(1950) = 1d 12'41". 165 sources are detected in the area surveyed which represents an increase of 60 objects. The fact that we have obtained near-infrared photometry of a fraction of the sample in three separate passbands (1.25, 1.65 and 2.2 microns) allows us to study via colour-colour and colour-magnitude diagrams, the combined effects of both the intrinsic properties of the sources and the overlaying extinction which, at near-infrared wavelengths, is obviously considerably smaller than in the optical. Added to this, such diagrams and other basic criteria were used to determine which stars are members of the embedded young stellar population, i.e. separating the young PMS stars from the population of "normal" background/foreground main sequence stars and giants. Additionally, high-resolution molecular line observations of the Serpens Nebula by White et al. (1995) were used to evaluate the extinction through each part of the cloud and allowed us to construct the dereddened K luminosity function of the cluster. To investigate the nature of the underlying Interstellar Mass Function (IMF), we calculated models which predict the evolution of the luminosity function of a cluster of PMS stars using the half-gaussian form of the Miller-Scalo IMF (Miller and Scalo 1979) and the slope of the mass-K luminosity relation as derived from transformed PMS tracks at each age and mass (d'Antona and Mazzitelli 1994). We then compared these models with the Serpens KLF to place constraints on the star-formation history and we found that a second, more recent (a few x 10^5), phase of star formation represents quite well the obse

Giovannetti, Philippe; Caux, Emmanuel

387

Patterns and Symmetries in the Visual Cortex and in Natural Images  

NASA Astrophysics Data System (ADS)

As borders between different entities, lines are an important element of natural images. Indeed, the neurons of the mammalian visual cortex are tuned to respond best to lines of a given orientation. This preferred orientation varies continuously across most of the cortex, but also has vortex-like singularities known as pinwheels. In attempting to describe such patterns of orientation preference, we are led to consider underlying rotation symmetries: Oriented segments in natural images tend to be collinear; neurons are more likely to be connected if their preferred orientations are aligned to their topographic separation. These are indications of a reduced symmetry requiring joint rotations of both orientation preference and the underlying topography. This is verified by direct statistical tests in both natural images and in cortical maps. Using the statistics of natural scenes we construct filters that are best suited to extracting information from such images, and find qualitative similarities to mammalian vision.

Lee, Ha Youn; Kardar, Mehran

2006-12-01

388

Multiline spectral imaging of dense cores in the Lupus molecular cloud  

NASA Astrophysics Data System (ADS)

The molecular clouds Lupus 1, 3 and 4 were mapped with the Mopra Telescope at 3 and 12 mm. Emission lines from high-density molecular tracers were detected, i.e. NH3 (1,1), NH3 (2,2), N2H+ (1-0), HC3N (3-2), HC3N (10-9), CS (2-1), CH3OH (20-10)A+ and CH3OH (2-1-1-1)E. Velocity gradients of more than 1 km s-1 are present in Lupus 1 and 3, and multiple gas components are present in these clouds along some lines of sight. Lupus 1 is the cloud richest in high-density cores: eight cores were detected in it, five cores were detected in Lupus 3 and only two in Lupus 4. The intensity of the three species HC3N, NH3 and N2H+ changes significantly in the various cores: cores that are brighter in HC3N are fainter or undetected in NH3 and N2H+ and vice versa. We found that the column density ratios HC3N/N2H+ and HC3N/NH3 change by 1 order of magnitude between the cores, indicating that also the chemical abundance of these species is different. The time-dependent chemical code that we used to model our cores shows that the HC3N/N2H+ and HC3N/NH3 ratios decrease with time, therefore the observed column density of these species can be used as an indicator of the chemical evolution of dense cores. On this basis we classified five out of eight cores in Lupus 1 and one out of five cores in Lupus 3 as very young protostars or pre-stellar cores. Comparing the millimetre core population with the population of the more evolved young stellar objects identified in the Spitzer surveys, we conclude that in Lupus 3 the bulk of the star formation activity has already passed and only a moderate number of stars are still forming. In contrast, in Lupus 1 star formation is ongoing and several dense cores are still in the pre-/protostellar phase. Lupus 4 is at an intermediate stage, with a smaller number of individual objects.

Benedettini, M.; Pezzuto, S.; Burton, M. G.; Viti, S.; Molinari, S.; Caselli, P.; Testi, L.

2012-01-01