Science.gov

Sample records for airborne scanning laser

  1. Visualisation of urban airborne laser scanning data with occlusion images

    NASA Astrophysics Data System (ADS)

    Hinks, Tommy; Carr, Hamish; Gharibi, Hamid; Laefer, Debra F.

    2015-06-01

    Airborne Laser Scanning (ALS) was introduced to provide rapid, high resolution scans of landforms for computational processing. More recently, ALS has been adapted for scanning urban areas. The greater complexity of urban scenes necessitates the development of novel methods to exploit urban ALS to best advantage. This paper presents occlusion images: a novel technique that exploits the geometric complexity of the urban environment to improve visualisation of small details for better feature recognition. The algorithm is based on an inversion of traditional occlusion techniques.

  2. Multispectral Airborne Laser Scanning for Automated Map Updating

    NASA Astrophysics Data System (ADS)

    Matikainen, Leena; Hyyppä, Juha; Litkey, Paula

    2016-06-01

    During the last 20 years, airborne laser scanning (ALS), often combined with multispectral information from aerial images, has shown its high feasibility for automated mapping processes. Recently, the first multispectral airborne laser scanners have been launched, and multispectral information is for the first time directly available for 3D ALS point clouds. This article discusses the potential of this new single-sensor technology in map updating, especially in automated object detection and change detection. For our study, Optech Titan multispectral ALS data over a suburban area in Finland were acquired. Results from a random forests analysis suggest that the multispectral intensity information is useful for land cover classification, also when considering ground surface objects and classes, such as roads. An out-of-bag estimate for classification error was about 3% for separating classes asphalt, gravel, rocky areas and low vegetation from each other. For buildings and trees, it was under 1%. According to feature importance analyses, multispectral features based on several channels were more useful that those based on one channel. Automatic change detection utilizing the new multispectral ALS data, an old digital surface model (DSM) and old building vectors was also demonstrated. Overall, our first analyses suggest that the new data are very promising for further increasing the automation level in mapping. The multispectral ALS technology is independent of external illumination conditions, and intensity images produced from the data do not include shadows. These are significant advantages when the development of automated classification and change detection procedures is considered.

  3. Urban Tree Classification Using Full-Waveform Airborne Laser Scanning

    NASA Astrophysics Data System (ADS)

    Koma, Zs.; Koenig, K.; Höfle, B.

    2016-06-01

    Vegetation mapping in urban environments plays an important role in biological research and urban management. Airborne laser scanning provides detailed 3D geodata, which allows to classify single trees into different taxa. Until now, research dealing with tree classification focused on forest environments. This study investigates the object-based classification of urban trees at taxonomic family level, using full-waveform airborne laser scanning data captured in the city centre of Vienna (Austria). The data set is characterised by a variety of taxa, including deciduous trees (beeches, mallows, plane trees and soapberries) and the coniferous pine species. A workflow for tree object classification is presented using geometric and radiometric features. The derived features are related to point density, crown shape and radiometric characteristics. For the derivation of crown features, a prior detection of the crown base is performed. The effects of interfering objects (e.g. fences and cars which are typical in urban areas) on the feature characteristics and the subsequent classification accuracy are investigated. The applicability of the features is evaluated by Random Forest classification and exploratory analysis. The most reliable classification is achieved by using the combination of geometric and radiometric features, resulting in 87.5% overall accuracy. By using radiometric features only, a reliable classification with accuracy of 86.3% can be achieved. The influence of interfering objects on feature characteristics is identified, in particular for the radiometric features. The results indicate the potential of using radiometric features in urban tree classification and show its limitations due to anthropogenic influences at the same time.

  4. Applying RANSAC Algorithm for Fitting Scanning Strips from Airborne Laser Scanning

    NASA Astrophysics Data System (ADS)

    Błaszczak-Bąk, Wioleta; Janicka, Joanna; Sobieraj-Żłobińska, Anna

    2016-12-01

    During the development of the data acquired by airborne laser scanning the important issue is the fitting and georeferencing of ALS point clouds by means of the tie surfaces and the reference planes. The process of scanning strips adjustment is based on mutual integration of point clouds (scanning strips) and their adaptation to the reference planes. In simultaneous adjustment all strips are combined into one geometrically coherent block, to which the coordinates are given. In the process of determining discrepancies between scanning strips it is important to determine the correct size of the shifts (offsets). Authors propose to do this by using RANSAC algorithm.

  5. Test field for airborne laser scanning in Finland

    NASA Astrophysics Data System (ADS)

    Ahokas, E.; Kaartinen, H.; Kukko, A.; Litkey, P.

    2014-11-01

    Airborne laser scanning (ALS) is a widely spread operational measurement tool for obtaining 3D coordinates of the ground surface. There is a need for calibrating the ALS system and a test field for ALS was established at the end of 2013. The test field is situated in the city of Lahti, about 100 km to the north of Helsinki. The size of the area is approximately 3.5 km × 3.2 km. Reference data was collected with a mobile laser scanning (MLS) system assembled on a car roof. Some streets were measured both ways and most of them in one driving direction only. The MLS system of the Finnish Geodetic Institute (FGI) consists of a navigation system (NovAtel SPAN GNSS-IMU) and a laser scanner (FARO Focus3D 120). In addition to the MLS measurements more than 800 reference points were measured using a Trimble R8 VRS-GNSS system. Reference points are along the streets, on parking lots, and white pedestrian crossing line corners which can be used as reference targets. The National Land Survey of Finland has already used this test field this spring for calibrating their Leica ALS-70 scanner. Especially it was easier to determine the encoder scale factor parameter using this test field. Accuracy analysis of the MLS points showed that the point height RMSE is 2.8 cm and standard deviation is 2.6 cm. Our purpose is to measure both more MLS data and more reference points in the test field area to get a better spatial coverage. Calibration flight heights are planned to be 1000 m and 2500 m above ground level. A cross pattern, southwest-northeast and northwest-southeast, will be flown both in opposite directions.

  6. Detection of windthrown trees using airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Nyström, Mattias; Holmgren, Johan; Fransson, Johan E. S.; Olsson, Håkan

    2014-08-01

    In this study, a method has been developed for the detection of windthrown trees under a forest canopy, using the difference between two elevation models created from the same high density (65 points/m2) airborne laser scanning data. The difference image showing objects near the ground was created by subtracting a standard digital elevation model (DEM) from a more detailed DEM created using an active surface algorithm. Template matching was used to automatically detect windthrown trees in the difference image. The 54 ha study area is located in hemi-boreal forest in southern Sweden (Lat. 58°29‧ N, Long. 13°38‧ E) and is dominated by Norway spruce (Picea abies) with 3.5% deciduous species (mostly birch) and 1.7% Scots pine (Pinus sylvestris). The result was evaluated using 651 field measured windthrown trees. At individual tree level, the detection rate was 38% with a commission error of 36%. Much higher detection rates were obtained for taller trees; 89% of the trees taller than 27 m were detected. For pine the individual tree detection rate was 82%, most likely due to the more easily visible stem and lack of branches. When aggregating the results to 40 m square grid cells, at least one tree was detected in 77% of the grid cells which according to the field measurements contained one or more windthrown trees.

  7. Footprint Map Partitioning Using Airborne Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Xiong, B.; Oude Elberink, S.; Vosselman, G.

    2016-06-01

    Nowadays many cities and countries are creating their 3D building models for a better daily management and smarter decision making. The newly created 3D models are required to be consistent with existing 2D footprint maps. Thereby the 2D maps are usually combined with height data for the task of 3D reconstruction. Many buildings are often composed by parts that are discontinuous over height. Building parts can be reconstructed independently and combined into a complete building. Therefore, most of the state-of-the-art work on 3D building reconstruction first decomposes a footprint map into parts. However, those works usually change the footprint maps for easier partitioning and cannot detect building parts that are fully inside the footprint polygon. In order to solve those problems, we introduce two methodologies, one more dependent on height data, and the other one more dependent on footprints. We also experimentally evaluate the two methodologies and compare their advantages and disadvantages. The experiments use Airborne Laser Scanning (ALS) data and two vector maps, one with 1:10,000 scale and another one with 1:500 scale.

  8. Estimation of terracing characteristics from airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Kokalj, Žiga

    2015-04-01

    Agricultural terraces are a fundamental morphological form of the Slovenian landscape. They are present in all of its diverse geographical regions, from Mediterranean and Dinaric hills and plateaus, Alpine mountains and plains, to Pannonian hills. New systematic research based on mapping aerial orthophotos and historical maps revealed previously unrecorded distribution and extent of terracing. However, the extensive overgrowing of the Slovenian countryside in the past century, when forest cover has grown from 40% to more than 60%, hid many of the terraces under a thick forest canopy. This is especially true for the higher and more remote areas where unfavourable natural conditions have coupled with depopulation processes. In such conditions, the only reasonable technique to observe cultural terraces and other remains of past human activities over large areas is airborne laser scanning. With the country-wide airborne lidar data becoming available, many new possibilities for discovery as well as quantitative analyses are becoming available. We explored manual and semiautomatic approaches to obtain terracing characteristics around representative villages of diverse landscape types. Individual terraces can be described with several attributes, such as riser slope gradient, riser height, tread area, length and width, ratio of length and width, altitude, location of the terrace in the thermal band, distance to the settlement, number and type of trees, distance between trees, and number of vineyard rows. Such characteristics can be derived manually, which can be painstakingly slow, but with relative precisions reaching the order of centimetres and decimetres, or semiautomatically, which is much faster, but with worse precision levels, mainly due to various outliers and errors in processing. The success of attribute derivation is highly dependent on raw lidar data acquisition parameters and processing. Manual interpretation has a distinct advantage of the possibility to

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

    PubMed

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

    2009-01-01

    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.

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

    PubMed Central

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

    2009-01-01

    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

  11. Tree-centric mapping of forest carbon density from airborne laser scanning and hyperspectral data.

    PubMed

    Dalponte, Michele; Coomes, David A

    2016-10-01

    Forests are a major component of the global carbon cycle, and accurate estimation of forest carbon stocks and fluxes is important in the context of anthropogenic global change. Airborne laser scanning (ALS) data sets are increasingly recognized as outstanding data sources for high-fidelity mapping of carbon stocks at regional scales.We develop a tree-centric approach to carbon mapping, based on identifying individual tree crowns (ITCs) and species from airborne remote sensing data, from which individual tree carbon stocks are calculated. We identify ITCs from the laser scanning point cloud using a region-growing algorithm and identifying species from airborne hyperspectral data by machine learning. For each detected tree, we predict stem diameter from its height and crown-width estimate. From that point on, we use well-established approaches developed for field-based inventories: above-ground biomasses of trees are estimated using published allometries and summed within plots to estimate carbon density.We show this approach is highly reliable: tests in the Italian Alps demonstrated a close relationship between field- and ALS-based estimates of carbon stocks (r(2) = 0·98). Small trees are invisible from the air, and a correction factor is required to accommodate this effect.An advantage of the tree-centric approach over existing area-based methods is that it can produce maps at any scale and is fundamentally based on field-based inventory methods, making it intuitive and transparent. Airborne laser scanning, hyperspectral sensing and computational power are all advancing rapidly, making it increasingly feasible to use ITC approaches for effective mapping of forest carbon density also inside wider carbon mapping programs like REDD++.

  12. Automated planimetric quality control in high accuracy airborne laser scanning surveys

    NASA Astrophysics Data System (ADS)

    Vosselman, George

    2012-11-01

    With the increasing point densities of airborne laser scanning surveys, the applications of the generated point clouds have evolved from the production of digital terrain models to 3D modelling of a wide variety of objects. Likewise in quality control procedures criteria for height accuracy are extended with measures to describe the planimetric accuracy. This paper introduces a measure for the potential accuracy of outlining objects in a point cloud. It describes how this accuracy can be verified with the use of ridge lines of gable roofs in strip overlaps. Because of the high accuracy of modern laser scanning surveys, the influence of roof tiles onto the estimation of ridge lines is explicitly modelled. New selection criteria are introduced that allow an automated, reliable and accurate extraction of ridge lines from point clouds. The applicability of the procedure is demonstrated in a pilot project in an area covering 100,000 ha with around 20 billion points.

  13. An entropy-based filtering approach for airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Zeng, Zhe; Wan, Jiaxin; Liu, Hui

    2016-03-01

    Parameter-tuning is a challenging task when generating digital terrain models from airborne laser scanning (light detection and ranging, LiDAR) data. To address this issue, this paper presents a filtering method for near-infrared laser scanning data that exploits the principle of entropy maximization as the optimization objective. The proposed approach generates ground elevation of point cloud by constructing a triangulated irregular network, calculates the entropy of the elevation from different parts, and automatically separates ground and non-ground points by the principle of entropy maximization. Experimental results from different ground surfaces show that the proposed entropy-based filtering method can effectively extract bare-earth points from the point cloud without adjusting thresholds.

  14. Volumetric evolution of Surtsey, Iceland, from topographic maps and scanning airborne laser altimetry

    USGS Publications Warehouse

    Garvin, J.B.; Williams, R.S.; Frawley, J.J.; Krabill, W.B.

    2000-01-01

    The volumetric evolution of Surtsey has been estimated on the basis of digital elevation models derived from NASA scanning airborne laser altimeter surveys (20 July 1998), as well as digitized 1:5,000-scale topographic maps produced by the National Land Survey of Iceland and by Norrman. Subaerial volumes have been computed from co-registered digital elevation models (DEM's) from 6 July 1968, 11 July 1975, 16 July 1993, and 20 July 1998 (scanning airborne laser altimetry), as well as true surface area (above mean sea level). Our analysis suggests that the subaerial volume of Surtsey has been reduced from nearly 0.100 km3 on 6 July 1968 to 0.075 km3 on 20 July 1998. Linear regression analysis of the temporal evolution of Surtsey's subaerial volume indicates that most of its subaerial surface will be at or below mean sea-level by approximately 2100. This assumes a conservative estimate of continuation of the current pace of marine erosion and mass-wasting on the island, including the indurated core of the conduits of the Surtur I and Surtur II eruptive vents. If the conduits are relatively resistant to marine erosion they will become sea stacks after the rest of the island has become a submarine shoal, and some portions of the island could survive for centuries. The 20 July 1998 scanning laser altimeter surveys further indicate rapid enlargement of erosional canyons in the northeastern portion of the partial tephra ring associated with Surtur I. Continued airborne and eventually spaceborne topographic surveys of Surtsey are planned to refine the inter-annual change of its subaerial volume.

  15. Towards Automatic Single-Sensor Mapping by Multispectral Airborne Laser Scanning

    NASA Astrophysics Data System (ADS)

    Ahokas, E.; Hyyppä, J.; Yu, X.; Liang, X.; Matikainen, L.; Karila, K.; Litkey, P.; Kukko, A.; Jaakkola, A.; Kaartinen, H.; Holopainen, M.; Vastaranta, M.

    2016-06-01

    This paper describes the possibilities of the Optech Titan multispectral airborne laser scanner in the fields of mapping and forestry. Investigation was targeted to six land cover classes. Multispectral laser scanner data can be used to distinguish land cover classes of the ground surface, including the roads and separate road surface classes. For forest inventory using point cloud metrics and intensity features combined, total accuracy of 93.5% was achieved for classification of three main boreal tree species (pine, spruce and birch).When using intensity features - without point height metrics - a classification accuracy of 91% was achieved for these three tree species. It was also shown that deciduous trees can be further classified into more species. We propose that intensity-related features and waveform-type features are combined with point height metrics for forest attribute derivation in area-based prediction, which is an operatively applied forest inventory process in Scandinavia. It is expected that multispectral airborne laser scanning can provide highly valuable data for city and forest mapping and is a highly relevant data asset for national and local mapping agencies in the near future.

  16. An automated method to register airborne and terrestrial laser scanning point clouds

    NASA Astrophysics Data System (ADS)

    Yang, Bisheng; Zang, Yufu; Dong, Zhen; Huang, Ronggang

    2015-11-01

    Laser scanning techniques have been widely used to capture three-dimensional (3D) point clouds of various scenes (e.g. urban scenes). In particular, airborne laser scanning (ALS) and mobile laser scanning (MLS), terrestrial laser scanning (TLS) are effective to capture point clouds from top or side view. Registering the complimentary point clouds captured by ALS and MLS/TLS provides an aligned data source for many purposes (e.g. 3D reconstruction). Among these MLS can be directly geo-referenced to ALS according to the equipped position systems. For small scanning areas or dense building areas, TLS is used instead of MLS. However, registering ALS and TLS datasets suffers from poor automation and robustness because of few overlapping areas and sparse corresponding geometric features. A robust method for the registration of TLS and ALS datasets is proposed, which has four key steps. (1) extracts building outlines from TLS and ALS data sets independently; (2) obtains the potential matching pairs of outlines according to the geometric constraints between building outlines; (3) constructs the Laplacian matrices of the extracted building outlines to model the topology between the geometric features; (4) calculates the correlation coefficients of the extracted geometric features by decomposing the Laplacian matrices into the spectral space, providing correspondences between the extracted features for coarse registration. Finally, the multi-line adjustment strategy is employed for the fine registration. The robustness and accuracy of the proposed method are verified using field data, demonstrating a reliable and stable solution to accurately register ALS and TLS datasets.

  17. Testing of Land Cover Classification from Multispectral Airborne Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Bakuła, K.; Kupidura, P.; Jełowicki, Ł.

    2016-06-01

    Multispectral Airborne Laser Scanning provides a new opportunity for airborne data collection. It provides high-density topographic surveying and is also a useful tool for land cover mapping. Use of a minimum of three intensity images from a multiwavelength laser scanner and 3D information included in the digital surface model has the potential for land cover/use classification and a discussion about the application of this type of data in land cover/use mapping has recently begun. In the test study, three laser reflectance intensity images (orthogonalized point cloud) acquired in green, near-infrared and short-wave infrared bands, together with a digital surface model, were used in land cover/use classification where six classes were distinguished: water, sand and gravel, concrete and asphalt, low vegetation, trees and buildings. In the tested methods, different approaches for classification were applied: spectral (based only on laser reflectance intensity images), spectral with elevation data as additional input data, and spectro-textural, using morphological granulometry as a method of texture analysis of both types of data: spectral images and the digital surface model. The method of generating the intensity raster was also tested in the experiment. Reference data were created based on visual interpretation of ALS data and traditional optical aerial and satellite images. The results have shown that multispectral ALS data are unlike typical multispectral optical images, and they have a major potential for land cover/use classification. An overall accuracy of classification over 90% was achieved. The fusion of multi-wavelength laser intensity images and elevation data, with the additional use of textural information derived from granulometric analysis of images, helped to improve the accuracy of classification significantly. The method of interpolation for the intensity raster was not very helpful, and using intensity rasters with both first and last return

  18. Coupling airborne laser scanning and acoustic Doppler current profiler data to model stream rating curves

    NASA Astrophysics Data System (ADS)

    Lam, N.; Lyon, S. W.; Kean, J. W.

    2015-12-01

    The rating curve enables the translation of water depth into discharge through a reference cross section. Errors in estimating stream channel geometry can therefore result in increased discharge uncertainty. This study investigates coupling national-scale airborne laser scanning (ALS) and acoustic Doppler current profiler (ADCP) bathymetric survey data for generating stream rating curves. Specifically, stream channel geometries were generated from coupled ALS and ADCP scanning data collected for a well-monitored site located in northern Sweden. These data were used to define the hydraulic geometry required by a physically-based 1-D hydraulic model. The results of our study demonstrate that the effects of potential scanning data errors on the model generated rating curve were less than the uncertainties due to stream gauging measurements and empirical rating curve fitting. Further analysis of the ALS data showed that an overestimation of the streambank elevation (the main scanning data error) was primarily due to vegetation that could be adjusted for through a root-mean-square-error bias correction. We consider these findings encouraging as hydrometric agencies can potentially leverage national-scale ALS and ADCP instrumentation to reduce the cost and effort required for maintaining and establish rating curves at gauging stations.

  19. Geodetic Imaging for Rapid Assessment of Earthquakes: Airborne Laser Scanning (ALS)

    NASA Astrophysics Data System (ADS)

    Carter, W. E.; Shrestha, R. L.; Glennie, C. L.; Sartori, M.; Fernandez-Diaz, J.; National CenterAirborne Laser Mapping Operational Center

    2010-12-01

    To the residents of an area struck by a strong earthquake quantitative information on damage to the infrastructure, and its attendant impact on relief and recovery efforts, is urgent and of primary concern. To earth scientists a strong earthquake offers an opportunity to learn more about earthquake mechanisms, and to compare their models with the real world, in hopes of one day being able to accurately predict the precise locations, magnitudes, and times of large (and potentially disastrous) earthquakes. Airborne laser scanning (also referred to as airborne LiDAR or Airborne Laser Swath Mapping) is particularly well suited for rapid assessment of earthquakes, both for immediately estimating the damage to infrastructure and for providing information for the scientific study of earthquakes. ALS observations collected at low altitude (500—1000m) from a relatively slow (70—100m/sec) aircraft can provide dense (5—15 points/m2) sets of surface features (buildings, vegetation, ground), extending over hundreds of square kilometers with turn around times of several hours to a few days. The actual response time to any given event depends on several factors, including such bureaucratic issues as approval of funds, export license formalities, and clearance to fly over the area to be mapped, and operational factors such as the deployment of the aircraft and ground teams may also take a number of days for remote locations. Of course the need for immediate mapping of earthquake damage generally is not as urgent in remote regions with less infrastructure and few inhabitants. During August 16-19, 2010 the National Center for Airborne Laser Mapping (NCALM) mapped the area affected by the magnitude 7.2 El Mayor-Cucapah Earthquake (Northern Baja California Earthquake), which occurred on April 4, 2010, and was felt throughout southern California, Arizona, Nevada, and Baja California North, Mexico. From initial ground observations the fault rupture appeared to extend 75 km

  20. High Resolution Airborne Laser Scanning and Hyperspectral Imaging with a Small Uav Platform

    NASA Astrophysics Data System (ADS)

    Gallay, Michal; Eck, Christoph; Zgraggen, Carlo; Kaňuk, Ján; Dvorný, Eduard

    2016-06-01

    The capabilities of unmanned airborne systems (UAS) have become diverse with the recent development of lightweight remote sensing instruments. In this paper, we demonstrate our custom integration of the state-of-the-art technologies within an unmanned aerial platform capable of high-resolution and high-accuracy laser scanning, hyperspectral imaging, and photographic imaging. The technological solution comprises the latest development of a completely autonomous, unmanned helicopter by Aeroscout, the Scout B1-100 UAV helicopter. The helicopter is powered by a gasoline two-stroke engine and it allows for integrating 18 kg of a customized payload unit. The whole system is modular providing flexibility of payload options, which comprises the main advantage of the UAS. The UAS integrates two kinds of payloads which can be altered. Both payloads integrate a GPS/IMU with a dual GPS antenna configuration provided by OXTS for accurate navigation and position measurements during the data acquisition. The first payload comprises a VUX-1 laser scanner by RIEGL and a Sony A6000 E-Mount photo camera. The second payload for hyperspectral scanning integrates a push-broom imager AISA KESTREL 10 by SPECIM. The UAS was designed for research of various aspects of landscape dynamics (landslides, erosion, flooding, or phenology) in high spectral and spatial resolution.

  1. Point-based and model-based geolocation analysis of airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Sefercik, Umut Gunes; Buyuksalih, Gurcan; Jacobsen, Karsten; Alkan, Mehmet

    2017-01-01

    Airborne laser scanning (ALS) is one of the most effective remote sensing technologies providing precise three-dimensional (3-D) dense point clouds. A large-size ALS digital surface model (DSM) covering the whole Istanbul province was analyzed by point-based and model-based comprehensive statistical approaches. Point-based analysis was performed using checkpoints on flat areas. Model-based approaches were implemented in two steps as strip to strip comparing overlapping ALS DSMs individually in three subareas and comparing the merged ALS DSMs with terrestrial laser scanning (TLS) DSMs in four other subareas. In the model-based approach, the standard deviation of height and normalized median absolute deviation were used as the accuracy indicators combined with the dependency of terrain inclination. The results demonstrate that terrain roughness has a strong impact on the vertical accuracy of ALS DSMs. From the relative horizontal shifts determined and partially improved by merging the overlapping strips and comparison of the ALS, and the TLS, data were found not to be negligible. The analysis of ALS DSM in relation to TLS DSM allowed us to determine the characteristics of the DSM in detail.

  2. Airborne Laser Scanning of Forest Stem Volume in a Mountainous Environment

    PubMed Central

    Hollaus, Markus; Wagner, Wolfgang; Maier, Bernhard; Schadauer, Klemens

    2007-01-01

    Airborne laser scanning (ALS) is an active remote sensing technique that uses the time-of-flight measurement principle to capture the three-dimensional structure of the earth's surface with pulsed lasers that transmit nanosecond-long laser pulses with a high pulse repetition frequency. Over forested areas most of the laser pulses are reflected by the leaves and branches of the trees, but a certain fraction of the laser pulses reaches the forest floor through small gaps in the canopy. Thus it is possible to reconstruct both the three-dimensional structure of the forest canopy and the terrain surface. For the retrieval of quantitative forest parameters such as stem volume or biomass it is necessary to use models that combine ALS with inventory data. One approach is to use multiplicative regression models that are trained with local inventory data. This method has been widely applied over boreal forest regions, but so far little experience exists with applying this method for mapping alpine forest. In this study the transferability of this approach to a 128 km2 large mountainous region in Vorarlberg, Austria, was evaluated. For the calibration of the model, inventory data as operationally collected by Austrian foresters were used. Despite these inventory data are based on variable sample plot sizes, they could be used for mapping stem volume for the entire alpine study area. The coefficient of determination R2 was 0.85 and the root mean square error (RMSE) 90.9 m3ha−1 (relative error of 21.4%) which is comparable to results of ALS studies conducted over topographically less complex environments. Due to the increasing availability, ALS data could become an operational part of Austrian's forest inventories.

  3. Processing of airborne laser scanning data to generate accurate DTM for floodplain wetland

    NASA Astrophysics Data System (ADS)

    Szporak-Wasilewska, Sylwia; Mirosław-Świątek, Dorota; Grygoruk, Mateusz; Michałowski, Robert; Kardel, Ignacy

    2015-10-01

    Structure of the floodplain, especially its topography and vegetation, influences the overland flow and dynamics of floods which are key factors shaping ecosystems in surface water-fed wetlands. Therefore elaboration of the digital terrain model (DTM) of a high spatial accuracy is crucial in hydrodynamic flow modelling in river valleys. In this study the research was conducted in the unique Central European complex of fens and marshes - the Lower Biebrza river valley. The area is represented mainly by peat ecosystems which according to EU Water Framework Directive (WFD) are called "water-dependent ecosystems". Development of accurate DTM in these areas which are overgrown by dense wetland vegetation consisting of alder forest, willow shrubs, reed, sedges and grass is very difficult, therefore to represent terrain in high accuracy the airborne laser scanning data (ALS) with scanning density of 4 points/m2 was used and the correction of the "vegetation effect" on DTM was executed. This correction was performed utilizing remotely sensed images, topographical survey using the Real Time Kinematic positioning and vegetation height measurements. In order to classify different types of vegetation within research area the object based image analysis (OBIA) was used. OBIA allowed partitioning remotely sensed imagery into meaningful image-objects, and assessing their characteristics through spatial and spectral scale. The final maps of vegetation patches that include attributes of vegetation height and vegetation spectral properties, utilized both the laser scanning data and the vegetation indices developed on the basis of airborne and satellite imagery. This data was used in process of segmentation, attribution and classification. Several different vegetation indices were tested to distinguish different types of vegetation in wetland area. The OBIA classification allowed correction of the "vegetation effect" on DTM. The final digital terrain model was compared and examined

  4. A wavelet based algorithm for DTM extraction from airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Xu, Liang; Yang, Yan; Tian, Qingjiu

    2007-06-01

    The automatic extraction of Digital Terrain Model (DTM) from point clouds acquired by airborne laser scanning (ALS) equipment remains a problem in ALS data filtering nowadays. Many filter algorithms have been developed to remove object points and outliers, and to extract DTM automatically. However, it is difficult to filter in areas where few points have identical morphological or geological features that can present the bare earth. Especially in sloped terrain covered by dense vegetation, points representing bare earth are often identified as noisy data below ground. To extract terrain surface in these areas, a new algorithm is proposed. First, the point clouds are cut into profiles based on a scan line segmentation algorithm. In each profile, a 1D filtering procedure is determined from the wavelet theory, which is superior in detecting high frequency discontinuities. After combining profiles from different directions, an interpolated grid data representing DTM is generated. In order to evaluate the performance of this new approach, we applied it to the data set used in the ISPRS filter test in 2003. 2 samples containing mostly vegetation on slopes have been processed by the proposed algorithm. It can be seen that it filtered most of the objects like vegetation and buildings in sloped area, and smoothed the hilly mountain to be more close to its real terrain surface.

  5. Research of the coastal zone by the airborne laser scanning data (Verbyanaya bay-bar, sea of Azov)

    NASA Astrophysics Data System (ADS)

    Pogorelov, Anatoliy V.; Antonenko, Mihail; Boyko, Evgeniy

    2015-06-01

    In the area Verbyanaya bay-bar (Sea of Azov) in an attempt to create large-scale cartographic base and subsequent thematic mapping of the geographical environment components airborne laser scanning and aerial photography were conducted. Airborne laser scanning data formed the basis of a comprehensive study of the coastal zone components. Methodical research apparatus includes receiving and processing technology of laser reflection points, constructing highprecision digital elevation model and raster surfaces. Mosaic of aerial photography is converted into a format mosaic - a geometrically correct image of the terrain. Set of high-precision digital surface models and thematic raster images obtained for specific dates, allows to analyze the dynamic adjustment of components of the coastal zone (shoreline, beach, shore dam with surge prism).

  6. Use of naturally available reference targets to calibrate airborne laser scanning intensity data.

    PubMed

    Vain, Ants; Kaasalainen, Sanna; Pyysalo, Ulla; Krooks, Anssi; Litkey, Paula

    2009-01-01

    We have studied the possibility of calibrating airborne laser scanning (ALS) intensity data, using land targets typically available in urban areas. For this purpose, a test area around Espoonlahti Harbor, Espoo, Finland, for which a long time series of ALS campaigns is available, was selected. Different target samples (beach sand, concrete, asphalt, different types of gravel) were collected and measured in the laboratory. Using tarps, which have certain backscattering properties, the natural samples were calibrated and studied, taking into account the atmospheric effect, incidence angle and flying height. Using data from different flights and altitudes, a time series for the natural samples was generated. Studying the stability of the samples, we could obtain information on the most ideal types of natural targets for ALS radiometric calibration. Using the selected natural samples as reference, the ALS points of typical land targets were calibrated again and examined. Results showed the need for more accurate ground reference data, before using natural samples in ALS intensity data calibration. Also, the NIR camera-based field system was used for collecting ground reference data. This system proved to be a good means for collecting in situ reference data, especially for targets with inhomogeneous surface reflection properties.

  7. Use of Naturally Available Reference Targets to Calibrate Airborne Laser Scanning Intensity Data

    PubMed Central

    Vain, Ants; Kaasalainen, Sanna; Pyysalo, Ulla; Krooks, Anssi; Litkey, Paula

    2009-01-01

    We have studied the possibility of calibrating airborne laser scanning (ALS) intensity data, using land targets typically available in urban areas. For this purpose, a test area around Espoonlahti Harbor, Espoo, Finland, for which a long time series of ALS campaigns is available, was selected. Different target samples (beach sand, concrete, asphalt, different types of gravel) were collected and measured in the laboratory. Using tarps, which have certain backscattering properties, the natural samples were calibrated and studied, taking into account the atmospheric effect, incidence angle and flying height. Using data from different flights and altitudes, a time series for the natural samples was generated. Studying the stability of the samples, we could obtain information on the most ideal types of natural targets for ALS radiometric calibration. Using the selected natural samples as reference, the ALS points of typical land targets were calibrated again and examined. Results showed the need for more accurate ground reference data, before using natural samples in ALS intensity data calibration. Also, the NIR camera-based field system was used for collecting ground reference data. This system proved to be a good means for collecting in situ reference data, especially for targets with inhomogeneous surface reflection properties. PMID:22574045

  8. Parallel Processing Method for Airborne Laser Scanning Data Using a PC Cluster and a Virtual Grid.

    PubMed

    Han, Soo Hee; Heo, Joon; Sohn, Hong Gyoo; Yu, Kiyun

    2009-01-01

    In this study, a parallel processing method using a PC cluster and a virtual grid is proposed for the fast processing of enormous amounts of airborne laser scanning (ALS) data. The method creates a raster digital surface model (DSM) by interpolating point data with inverse distance weighting (IDW), and produces a digital terrain model (DTM) by local minimum filtering of the DSM. To make a consistent comparison of performance between sequential and parallel processing approaches, the means of dealing with boundary data and of selecting interpolation centers were controlled for each processing node in parallel approach. To test the speedup, efficiency and linearity of the proposed algorithm, actual ALS data up to 134 million points were processed with a PC cluster consisting of one master node and eight slave nodes. The results showed that parallel processing provides better performance when the computational overhead, the number of processors, and the data size become large. It was verified that the proposed algorithm is a linear time operation and that the products obtained by parallel processing are identical to those produced by sequential processing.

  9. Assessing and modeling moose (Alces alces) habitats with airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Melin, M.; Packalén, P.; Matala, J.; Mehtätalo, L.; Pusenius, J.

    2013-08-01

    In the analysis of forest resources, the use of ALS (airborne laser scanning) enables detailed three dimensional (3D) descriptions of forests and their vegetation. Simultaneously, ecologists have recognized that 3D information on vegetation is highly important in analyzing the habitat suitability of a given site. Recently, animals’ habitat preferences have been analyzed, for example, with GPS-collared animals. This has resulted in detailed knowledge about the animals’ movements both spatially and temporally. This study combines 3D information on vegetation obtained from ALS data with information about animal locations from GPS data. The aim was to map and analyze the habitat preferences of moose. The study area was located on the west coast of Finland. The data consisted of 18 GPS-collared moose (monitored from 2009 to 2010) and ALS data collected in 2010. We investigated how habitat structure changes as a function of distance to observed moose locations and how observed moose locations differ from randomly selected locations in terms of 3D structure. We also created a model-based habitat suitability map and tested it against moose occurrences. The results suggested that there are clear differences between the areas occupied and not occupied by moose and that these differences can be detected from ALS data. More importantly, ALS proved its potential in linking 3D descriptions of vegetation directly to observed moose locations without any proxy variables. These observations strongly support future studies.

  10. Performance analysis of freeware filtering algorithms for determining ground surface from airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Julge, Kalev; Ellmann, Artu; Gruno, Anti

    2014-01-01

    Numerous filtering algorithms have been developed in order to distinguish the ground surface from nonground points acquired by airborne laser scanning. These algorithms automatically attempt to determine the ground points using various features such as predefined parameters and statistical analysis. Their efficiency also depends on landscape characteristics. The aim of this contribution is to test the performance of six common filtering algorithms embedded in three freeware programs. The algorithms' adaptive TIN, elevation threshold with expand window, maximum local slope, progressive morphology, multiscale curvature, and linear prediction were tested on four relatively large (4 to 8 km2) and diverse landscape areas, which included steep sloped hills, urban areas, ridge-like eskers, and a river valley. The results show that in diverse test areas each algorithm yields various commission and omission errors. It appears that adaptive TIN is suitable in urban areas while the multiscale curvature algorithm is best suited in wooded areas. The multiscale curvature algorithm yielded the overall best results with average root-mean-square error values of 0.35 m.

  11. Parallel Processing Method for Airborne Laser Scanning Data Using a PC Cluster and a Virtual Grid

    PubMed Central

    Han, Soo Hee; Heo, Joon; Sohn, Hong Gyoo; Yu, Kiyun

    2009-01-01

    In this study, a parallel processing method using a PC cluster and a virtual grid is proposed for the fast processing of enormous amounts of airborne laser scanning (ALS) data. The method creates a raster digital surface model (DSM) by interpolating point data with inverse distance weighting (IDW), and produces a digital terrain model (DTM) by local minimum filtering of the DSM. To make a consistent comparison of performance between sequential and parallel processing approaches, the means of dealing with boundary data and of selecting interpolation centers were controlled for each processing node in parallel approach. To test the speedup, efficiency and linearity of the proposed algorithm, actual ALS data up to 134 million points were processed with a PC cluster consisting of one master node and eight slave nodes. The results showed that parallel processing provides better performance when the computational overhead, the number of processors, and the data size become large. It was verified that the proposed algorithm is a linear time operation and that the products obtained by parallel processing are identical to those produced by sequential processing. PMID:22574032

  12. Integrating optical satellite data and airborne laser scanning in habitat classification for wildlife management

    NASA Astrophysics Data System (ADS)

    Nijland, W.; Coops, N. C.; Nielsen, S. E.; Stenhouse, G.

    2015-06-01

    Wildlife habitat selection is determined by a wide range of factors including food availability, shelter, security and landscape heterogeneity all of which are closely related to the more readily mapped landcover types and disturbance regimes. Regional wildlife habitat studies often used moderate resolution multispectral satellite imagery for wall to wall mapping, because it offers a favourable mix of availability, cost and resolution. However, certain habitat characteristics such as canopy structure and topographic factors are not well discriminated with these passive, optical datasets. Airborne laser scanning (ALS) provides highly accurate three dimensional data on canopy structure and the underlying terrain, thereby offers significant enhancements to wildlife habitat mapping. In this paper, we introduce an approach to integrate ALS data and multispectral images to develop a new heuristic wildlife habitat classifier for western Alberta. Our method combines ALS direct measures of canopy height, and cover with optical estimates of species (conifer vs. deciduous) composition into a decision tree classifier for habitat - or landcover types. We believe this new approach is highly versatile and transferable, because class rules can be easily adapted for other species or functional groups. We discuss the implications of increased ALS availability for habitat mapping and wildlife management and provide recommendations for integrating multispectral and ALS data into wildlife management.

  13. Landslides Identification Using Airborne Laser Scanning Data Derived Topographic Terrain Attributes and Support Vector Machine Classification

    NASA Astrophysics Data System (ADS)

    Pawłuszek, Kamila; Borkowski, Andrzej

    2016-06-01

    Since the availability of high-resolution Airborne Laser Scanning (ALS) data, substantial progress in geomorphological research, especially in landslide analysis, has been carried out. First and second order derivatives of Digital Terrain Model (DTM) have become a popular and powerful tool in landslide inventory mapping. Nevertheless, an automatic landslide mapping based on sophisticated classifiers including Support Vector Machine (SVM), Artificial Neural Network or Random Forests is often computationally time consuming. The objective of this research is to deeply explore topographic information provided by ALS data and overcome computational time limitation. For this reason, an extended set of topographic features and the Principal Component Analysis (PCA) were used to reduce redundant information. The proposed novel approach was tested on a susceptible area affected by more than 50 landslides located on Rożnów Lake in Carpathian Mountains, Poland. The initial seven PCA components with 90% of the total variability in the original topographic attributes were used for SVM classification. Comparing results with landslide inventory map, the average user's accuracy (UA), producer's accuracy (PA), and overall accuracy (OA) were calculated for two models according to the classification results. Thereby, for the PCA-feature-reduced model UA, PA, and OA were found to be 72%, 76%, and 72%, respectively. Similarly, UA, PA, and OA in the non-reduced original topographic model, was 74%, 77% and 74%, respectively. Using the initial seven PCA components instead of the twenty original topographic attributes does not significantly change identification accuracy but reduce computational time.

  14. Wide-Area Mapping of Forest with National Airborne Laser Scanning and Field Inventory Datasets

    NASA Astrophysics Data System (ADS)

    Monnet, J.-M.; Ginzler, C.; Clivaz, J.-C.

    2016-06-01

    Airborne laser scanning (ALS) remote sensing data are now available for entire countries such as Switzerland. Methods for the estimation of forest parameters from ALS have been intensively investigated in the past years. However, the implementation of a forest mapping workflow based on available data at a regional level still remains challenging. A case study was implemented in the Canton of Valais (Switzerland). The national ALS dataset and field data of the Swiss National Forest Inventory were used to calibrate estimation models for mean and maximum height, basal area, stem density, mean diameter and stem volume. When stratification was performed based on ALS acquisition settings and geographical criteria, satisfactory prediction models were obtained for volume (R2 = 0.61 with a root mean square error of 47 %) and basal area (respectively 0.51 and 45 %) while height variables had an error lower than 19%. This case study shows that the use of nationwide ALS and field datasets for forest resources mapping is cost efficient, but additional investigations are required to handle the limitations of the input data and optimize the accuracy.

  15. Integration of Airborne Laser Scanning Altimetry Data in Alpine Geomorphological and Hazard Studies

    NASA Astrophysics Data System (ADS)

    Seijmonsbergen, A. C.

    2007-12-01

    A digital terrain and surface model derived from an airborne laser scanning (ALS) altimetry dataset was used in the Austrian Alps for the preparation, improvement and the evaluation of a digital geomorphological hazard map. The geomorphology in the study area consists of a wide variety of landforms, which include glacial landforms such as cirques, hanging valleys, and moraine deposits, of pre- and postglacial mass movement landforms and processes, such as deep seated slope failures, rock fall, debris flows and solifluction. The area includes naked and covered gypsum karst, collapse dolines and fluvial landforms and deposits such as river terraces, incisions, alluvial fans and gullies. A detailed symbol based paper geomorphological map served as a basis for the digitalization of basic morphogenetic landform and process units. These units were assigned a `geomorphological unit type`, `hazard type` and `activity` code in the attribute table, according to a morphogenetic classification scheme. Selected zonal statistical attributes - mean height, aspect and slope angle - were calculated in a GIS using the vector based morphogenetic landform and process units and the underlying 1m resolution laser altimetry raster dataset. This statistical information was added to the attribute table of the `geomorphological hazard map`. Interpretation of the zonal statistical information shows that indicative topographic signatures exist for the various geomorphological and hazard units in this region of the Alps. Based on this experience a further step is made towards semi-automated geomorphological hazard classification of segmented laser altimetry data using expert knowledge rules. The first results indicate a classification accuracy of 50-70 percent for most landform associations. Areas affected by slide processes resulted in less accurate classification, probably because of their polygenetic history in this area. It is concluded that the use of lidar data improves visual

  16. Accuracy in estimation of timber assortments and stem distribution - A comparison of airborne and terrestrial laser scanning techniques

    NASA Astrophysics Data System (ADS)

    Kankare, Ville; Vauhkonen, Jari; Tanhuanpää, Topi; Holopainen, Markus; Vastaranta, Mikko; Joensuu, Marianna; Krooks, Anssi; Hyyppä, Juha; Hyyppä, Hannu; Alho, Petteri; Viitala, Risto

    2014-11-01

    Detailed information about timber assortments and diameter distributions is required in forest management. Forest owners can make better decisions concerning the timing of timber sales and forest companies can utilize more detailed information to optimize their wood supply chain from forest to factory. The objective here was to compare the accuracies of high-density laser scanning techniques for the estimation of tree-level diameter distribution and timber assortments. We also introduce a method that utilizes a combination of airborne and terrestrial laser scanning in timber assortment estimation. The study was conducted in Evo, Finland. Harvester measurements were used as a reference for 144 trees within a single clear-cut stand. The results showed that accurate tree-level timber assortments and diameter distributions can be obtained, using terrestrial laser scanning (TLS) or a combination of TLS and airborne laser scanning (ALS). Saw log volumes were estimated with higher accuracy than pulpwood volumes. The saw log volumes were estimated with relative root-mean-squared errors of 17.5% and 16.8% with TLS and a combination of TLS and ALS, respectively. The respective accuracies for pulpwood were 60.1% and 59.3%. The differences in the bucking method used also caused some large errors. In addition, tree quality factors highly affected the bucking accuracy, especially with pulpwood volume.

  17. development of a medium repetition rate (10 Hz - 500 Hz) diode pumped laser transmitter for airborne scanning altimetry

    NASA Technical Reports Server (NTRS)

    Coyle, D. Barry; Lindauer, Steven J., II; Kay, Richard B.

    1998-01-01

    Since the late 1980's, NASA has developed several small, all-solid state lasers of low repetition rates for use as transmitters in prototype LIDAR and raster scanned altimetry retrieval systems. Our early laser transmitters were developed for high resolution airborne altimetry which employed cavity dumping techniques to produce a pulse shape with a 1 ns rise time. The first such laser was the SUMR (Sub-millimeter resolution) transmitter which used a side pumped, D-shaped half-rod of Nd:YAG for the oscillator active media and produced approximately 3 ns pulses of 100 micro-J energy at a 40 Hz repetition rate. (Coyle and Blair, 1993; Coyle et al., 1995) After several upgrades to improve rep rate and pulse energy, the final version produced 1.2 mJ pulses at 120 Hz with a 3.7 ns pulse width. The laser has become known as SPLT (Sharp Pulsed Laser Transmitter), and has flown successfully on a variety of airborne altimetry missions. (Coyle and Blair, 1995; Blair et al., 1994) From building these systems, we have accrued valuable experience in delivering field-deployable lasers and have become aware of the advantages and disadvantages of employing new technologies. For example, even though the laser's main operating environment is in a "cold" aircraft during flight, the laser must still operate in very warm temperatures. This is important if the mission is based in the desert or a tropical climate since ground calibration data from stationary targets must be gathered before and after each data flight. Because conductive cooling is much more convenient than closed loop water flow, achieving the highest possible laser efficiency is becoming a high priority when designing a flight laser. This is especially true for lasers with higher pulse energies and repetition rates which are needed for high altitude scanning altimeters and LIDARs.

  18. Mapping of local-scale flooding on vegetated floodplains from radiometrically calibrated airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Malinowski, Radosław; Höfle, Bernhard; König, Kristina; Groom, Geoffrey; Schwanghart, Wolfgang; Heckrath, Goswin

    2014-05-01

    The agricultural use of riverine lowlands is often dependent on complex hydrological regimes including localized flooding. Knowledge about spatio-temporal inundation patterns enables a better understanding of the state of agricultural areas in lowlands and provides valuable and objective information on land suitability for land use administration and environmental planning. Data from Airborne Laser Scanning (ALS), also referred to as LiDAR, have become one of the most important sources of elevation data during the last two decades. Recently, geometric and radiometric attributes of ALS have also been explored for analysing the extent of water surfaces. Thus, the main objective of this work is to develop a method for mapping the spatial extent of floodplain inundation by means of remote sensing data. Our study focusses on analysing floodwaters partly covered by some vegetation, which is a major challenge in flood mapping. We hypothesize that ALS data due to its high sampling density and high rate of canopy penetration can effectively be used for floodwater detection in such areas. This research utilizes full-waveform ALS data with an average point density of 20 points/m2 obtained for an area of ca. 8 km2 of the Nørreå River valley in Jutland, Denmark. The study area is characterised by the presence of improved or semi-improved grasslands (meadows and pasture), few arable fields, irregularly scattered group of trees and bushes, and an extensive ditch network. Our approach is based on an inspection of properties of single laser points with regard to water vs. vegetation coverage within the laser footprint, which is compared with very detailed field reference data. Exploratory analysis and classification of ALS data were preceded by radiometric calibration of point cloud data, utilizing in situ measurements of reference targets reflectance. The resulting calibration derivatives provide very stable estimates of surface characteristics and are used as the main input in

  19. Evaluation of Vertical Lacunarity Profiles in Forested Areas Using Airborne Laser Scanning Point Clouds

    NASA Astrophysics Data System (ADS)

    Székely, B.; Kania, A.; Standovár, T.; Heilmeier, H.

    2016-06-01

    The horizontal variation and vertical layering of the vegetation are important properties of the canopy structure determining the habitat; three-dimensional (3D) distribution of objects (shrub layers, understory vegetation, etc.) is related to the environmental factors (e.g., illumination, visibility). It has been shown that gaps in forests, mosaic-like structures are essential to biodiversity; various methods have been introduced to quantify this property. As the distribution of gaps in the vegetation is a multi-scale phenomenon, in order to capture it in its entirety, scale-independent methods are preferred; one of these is the calculation of lacunarity. We used Airborne Laser Scanning point clouds measured over a forest plantation situated in a former floodplain. The flat topographic relief ensured that the tree growth is independent of the topographic effects. The tree pattern in the plantation crops provided various quasi-regular and irregular patterns, as well as various ages of the stands. The point clouds were voxelized and layers of voxels were considered as images for two-dimensional input. These images calculated for a certain vicinity of reference points were taken as images for the computation of lacunarity curves, providing a stack of lacunarity curves for each reference points. These sets of curves have been compared to reveal spatial changes of this property. As the dynamic range of the lacunarity values is very large, the natural logarithms of the values were considered. Logarithms of lacunarity functions show canopy-related variations, we analysed these variations along transects. The spatial variation can be related to forest properties and ecology-specific aspects.

  20. Airborne laser scanning of forested landslides characterization: Terrain model quality and visualization

    NASA Astrophysics Data System (ADS)

    Razak, K. A.; Straatsma, M. W.; van Westen, C. J.; Malet, J.-P.; de Jong, S. M.

    2011-03-01

    Mapping complex landslides under forested terrain requires an appropriate quality of digital terrain models (DTMs), which preserve small diagnostic features for landslide classification such as primary and secondary scarps, cracks, and displacement structures (flow-type and rigid-type). Optical satellite imagery, aerial photographs and synthetic aperture radar images are less effective to create reliable DTMs under tree coverage. Here, we utilized a very high density airborne laser scanning (ALS) data, with a point density of 140 points m - 2 for generating a high quality DTM for mapping landslides in forested terrain in the Barcelonnette region, the Southern French Alps. We quantitatively evaluated the preservation of morphological features and qualitatively assessed the visualization of ALS-derived DTMs. We presented a filter parameterization method suitable for landslide mapping and compared it with two default filters from the hierarchical robust interpolation (HRI) and one default filter from the progressive TIN densification (PTD) method. The results indicate that the vertical accuracy of the DTM derived from the landslide filter is about 0.04 m less accurate than that from the PTD filter. However, the landslide filter yields a better quality of the image for the recognition of small diagnostic features as depicted by expert image interpreters. Several DTM visualization techniques were compared for visual interpretation. The openness map visualized in a stereoscopic model reveals more morphologically relevant features for landslide mapping than the other filter products. We also analyzed the minimal point density in ALS data for landslide mapping and found that a point density of more than 6 points m - 2 is considered suitable for a detailed analysis of morphological features. This study illustrates the suitability of high density ALS data with an appropriate parameterization for the bare-earth extraction used for landslide identification and characterization

  1. Algorithm for the Automatic Estimation of Agricultural Tree Geometric Parameters Using Airborne Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Hadaś, E.; Borkowski, A.; Estornell, J.

    2016-06-01

    The estimation of dendrometric parameters has become an important issue for the agricultural planning and management. Since the classical field measurements are time consuming and inefficient, Airborne Laser Scanning (ALS) data can be used for this purpose. Point clouds acquired for orchard areas allow to determine orchard structures and geometric parameters of individual trees. In this research we propose an automatic method that allows to determine geometric parameters of individual olive trees using ALS data. The method is based on the α-shape algorithm applied for normalized point clouds. The algorithm returns polygons representing crown shapes. For points located inside each polygon, we select the maximum height and the minimum height and then we estimate the tree height and the crown base height. We use the first two components of the Principal Component Analysis (PCA) as the estimators for crown diameters. The α-shape algorithm requires to define the radius parameter R. In this study we investigated how sensitive are the results to the radius size, by comparing the results obtained with various settings of the R with reference values of estimated parameters from field measurements. Our study area was the olive orchard located in the Castellon Province, Spain. We used a set of ALS data with an average density of 4 points m-2. We noticed, that there was a narrow range of the R parameter, from 0.48 m to 0.80 m, for which all trees were detected and for which we obtained a high correlation coefficient (> 0.9) between estimated and measured values. We compared our estimates with field measurements. The RMSE of differences was 0.8 m for the tree height, 0.5 m for the crown base height, 0.6 m and 0.4 m for the longest and shorter crown diameter, respectively. The accuracy obtained with the method is thus sufficient for agricultural applications.

  2. Extracting Roof Parameters and Heat Bridges Over the City of Oldenburg from Hyperspectral, Thermal, and Airborne Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Bannehr, L.; Luhmann, Th.; Piechel, J.; Roelfs, T.; Schmidt, An.

    2011-09-01

    Remote sensing methods are used to obtain different kinds of information about the state of the environment. Within the cooperative research project HiReSens, funded by the German BMBF, a hyperspectral scanner, an airborne laser scanner, a thermal camera, and a RGB-camera are employed on a small aircraft to determine roof material parameters and heat bridges of house tops over the city Oldenburg, Lower Saxony. HiReSens aims to combine various geometrical highly resolved data in order to achieve relevant evidence about the state of the city buildings. Thermal data are used to obtain the energy distribution of single buildings. The use of hyperspectral data yields information about material consistence of roofs. From airborne laser scanning data (ALS) digital surface models are inferred. They build the basis to locate the best orientations for solar panels of the city buildings. The combination of the different data sets offers the opportunity to capitalize synergies between differently working systems. Central goals are the development of tools for the collection of heat bridges by means of thermal data, spectral collection of roofs parameters on basis of hyperspectral data as well as 3D-capture of buildings from airborne lasers scanner data. Collecting, analyzing and merging of the data are not trivial especially not when the resolution and accuracy is aimed in the domain of a few decimetre. The results achieved need to be regarded as preliminary. Further investigations are still required to prove the accuracy in detail.

  3. Airborne Laser Scanning - based vegetation classification in grasslands: a feasibility study

    NASA Astrophysics Data System (ADS)

    Zlinszky, András; Vári, Ágnes; Deák, Balázs; Mücke, Werner; Székely, Balázs

    2013-04-01

    Airborne Laser Scanning is traditionally used for topography mapping, exploiting its ability to map terrain elevation under vegetation cover. Parallel to this, the application of ALS for vegetation classification and mapping of ecological variables is rapidly emerging. Point clouds surveyed by ALS provide accurate representations of vegetation structure and are therefore considered suitable for mapping vegetation classes as long as their vertical structure is characteristic. For this reason, most ALS-based vegetation mapping studies have been carried out in forests, with some rare applications for shrublands or tall grass vegetation such as reeds. The use of remote-sensing derived vegetation maps is widespread in ecological research and is also gaining importance in practical conservation. There is an increasing demand for reliable, high-resolution datasets covering large protected areas. ALS can provide both the coverage and the high resolution, and can prove to be an economical solution due to the potential for automatic processing and the wide range of uses that allows spreading costs. Grasslands have a high importance in nature conservation as due to the drastical land use changes (arable lands, afforestation, fragmentation by linear structures) in the last centuries the extent of these habitats have been considerably reduced. Among the habitat types protected by the Habitat Directive of the Natura 2000 system, several grassland habitat types (e.g. hay meadows, dry grasslands harbouring rare Orchid species) have special priority for conservation. For preserving these habitat types application of a proper management - including mowing or grazing - has a crucial role. Therefore not only the mapping of the locations of habitats but the way of management is needed for representing the natural processes. The objective of this study was to test the applicability of airborne laser scanning for ecological vegetation mapping in and around grasslands. The study site is

  4. Extraction of Forest Roads from Full-waveform Airborne Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Djuricic, Ana; Hollaus, Markus

    2013-04-01

    The knowledge about the position of forest roads is important for the management and protection of forests. Most often this information is not available on a digital form so that it can be integrated into a GIS to use it e.g. for routing applications or to plan harvesting activities. Furthermore, the available information about forest roads is often not up-to-date. The extraction of forest roads from remote sensing data i.e. aerial photographs is often limited due to the visibility of the terrain within a forest. The increasing availability of airborne laser scanning (ALS) data has changed this situation during the last years. As an active measurement system ALS provide geometric information from the forest floor as well as the forest canopy. Additionally, the new generation of ALS sensors, the so-called full-waveform sensors provide in addition to the geometric information (i.e. 3D position, echo width) radiometric information (i.e. backscatter cross section) about the backscattering objects, which are excellent data sources to describe the terrain surface within a forest. Thus the aim of this study is to develop a semi-automatic method to extract the position of forest roads from full-waveform ALS data. Based on the 3D point cloud different raster layers were derived such as the digital terrain model (DTM), the slope, the backscatter cross section, different roughness parameters (i.e. echo width, standard deviation of plane fitting residuals of terrain points), the vertical component of the surface normals and the normalized digital surface model (nDSM), which represents the object height above the natural ground. The developed workflow classifies each input raster separately into the classes roads and non-roads. Morphological operations were applied on the classified raster datasets to smooth the outline of the extracted roads and to remove any small gaps in the detected roads. Several raster outputs were combined and used further for additional GIS analysis and

  5. Semi-automatic mapping of cultural heritage from airborne laser scanning using deep learning

    NASA Astrophysics Data System (ADS)

    Due Trier, Øivind; Salberg, Arnt-Børre; Holger Pilø, Lars; Tonning, Christer; Marius Johansen, Hans; Aarsten, Dagrun

    2016-04-01

    This paper proposes to use deep learning to improve semi-automatic mapping of cultural heritage from airborne laser scanning (ALS) data. Automatic detection methods, based on traditional pattern recognition, have been applied in a number of cultural heritage mapping projects in Norway for the past five years. Automatic detection of pits and heaps have been combined with visual interpretation of the ALS data for the mapping of deer hunting systems, iron production sites, grave mounds and charcoal kilns. However, the performance of the automatic detection methods varies substantially between ALS datasets. For the mapping of deer hunting systems on flat gravel and sand sediment deposits, the automatic detection results were almost perfect. However, some false detections appeared in the terrain outside of the sediment deposits. These could be explained by other pit-like landscape features, like parts of river courses, spaces between boulders, and modern terrain modifications. However, these were easy to spot during visual interpretation, and the number of missed individual pitfall traps was still low. For the mapping of grave mounds, the automatic method produced a large number of false detections, reducing the usefulness of the semi-automatic approach. The mound structure is a very common natural terrain feature, and the grave mounds are less distinct in shape than the pitfall traps. Still, applying automatic mound detection on an entire municipality did lead to a new discovery of an Iron Age grave field with more than 15 individual mounds. Automatic mound detection also proved to be useful for a detailed re-mapping of Norway's largest Iron Age grave yard, which contains almost 1000 individual graves. Combined pit and mound detection has been applied to the mapping of more than 1000 charcoal kilns that were used by an iron work 350-200 years ago. The majority of charcoal kilns were indirectly detected as either pits on the circumference, a central mound, or both

  6. Airborne laser scanning based quantification of dead-ice melting in recently deglaciated terrain

    NASA Astrophysics Data System (ADS)

    Klug, C.; Sailer, R.; Schümberg, M.; Stötter, J.

    2012-04-01

    Dead-ice is explained as stagnant glacial ice, not influenced by glacier flow anymore. Whenever glaciers have negative mass balances and an accumulation of debris-cover on the surface, dead-ice may form. Although, there are numerous conceptual process-sediment-landform models for the melt-out of dead-ice bodies and areas of dead-ice environments at glacier margins are easily accessible, just a few quantitative studies of dead-ice melting have been carried out so far. Processes and rates of dead-ice melting are commonly believed to be controlled by climate and debris-cover properties, but there is still a lack of knowledge about this fact. This study has a focus on the quantification of process induced volumetric changes caused by dead-ice melting. The research for this project was conducted at Hintereisferner (Ötztal Alps, Austria), Gepatschferner (Ötztal Alps, Austria) and Schrankar (Stubai Alps, Austria), areas for which a good data basis of ALS (Airborne Laser Scanning) measurements is available. 'Hintereisferner' can be characterized as a typical high alpine environment in mid-latitudes, which ranges between approximately 2250 m and 3740 m a.s.l.. The Hintereisferner region has been investigated intensively since many decades. Two dead ice bodies at the orographic right side and one at the orographic left side of the Hintereisferner glacier terminus (approx. at 2500 m to 2550 m a.s.l.) were identified. Since 2001, ALS measurements have been carried out regularly at Hintereisferner resulting in a unique data record of 21 ALS flight campaigns, allowing long-term explorations of the two dead-ice areas. The second study area of 'Gepatschferner' in the Kaunertal ranges between 2060 m and 3520 m a.s.l. and is the second largest glacier of Austria. Near the glacier tongue at the orographic right side a significant dead ice body has formed. The ALS data used for quantification include a period of time of 4 years (2006 - 2010). 'Schrankar' is located in the Western

  7. Mapping tree health using airborne full-waveform laser scans and hyperspectral imagery: a case study for floodplain eucalypt forest

    NASA Astrophysics Data System (ADS)

    Shendryk, I.; Tulbure, M. G.; Broich, M.

    2014-12-01

    Barmah-Millewa Forest (BMF), the largest River Red Gum forest in the world, located in south-eastern Australia is suffering from severe dieback, thus diminishing its ecological and economical value. Previous research showed that dieback is a good predictor of the forest health and stressed the need for BMF health mapping and change monitoring. In this respect, airborne laser scanning and hyperspectral imaging offer extensive spatial and spectral coverage of measurements and represent an ideal tool for forest health mapping at individual tree scale. The aim of this project is to quantify the health of individual, structurally complex floodplain eucalypt trees by integrating airborne hyperspectral imagery, full-waveform laser scans and field measurements. An aerial survey, conducted in May 2014, was designed to provide a representative sample of BMF tree health. The positioning of 17 flight lines aimed to capture the heterogeneity of the forest health and flood frequency. Preliminary analysis of the aerial remote sensing data with regards to chlorophyll concentrations, dieback levels and canopy densities allowed us to target our field campaign (conducted in June 2014). Field measurements included accurate position measurements, LAI, visual assessment, spectral measurement and mensuration of individual trees in 30 m2 plots. For detection of individual tree trunks from airborne laser scans we used a novel approach based on Euclidean distance clustering, taking advantage of the intensity and pulse width difference between woody and leaf tree compartments. The detected trunks were used to seed a minimum cut algorithm for tree crown delineation. In situ measurements confirmed the high structural diversity of the forest and allowed the calibration of the tree detection algorithm. An overall accuracy of the tree detection of 54% and 67% was achieved for trees with circumference over 40 cm and over 100 cm respectively. As a further step, 3D point clusters representing

  8. Estimation of regeneration coverage in a temperate forest by 3D segmentation using airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Amiri, Nina; Yao, Wei; Heurich, Marco; Krzystek, Peter; Skidmore, Andrew K.

    2016-10-01

    Forest understory and regeneration are important factors in sustainable forest management. However, understanding their spatial distribution in multilayered forests requires accurate and continuously updated field data, which are difficult and time-consuming to obtain. Therefore, cost-efficient inventory methods are required, and airborne laser scanning (ALS) is a promising tool for obtaining such information. In this study, we examine a clustering-based 3D segmentation in combination with ALS data for regeneration coverage estimation in a multilayered temperate forest. The core of our method is a two-tiered segmentation of the 3D point clouds into segments associated with regeneration trees. First, small parts of trees (super-voxels) are constructed through mean shift clustering, a nonparametric procedure for finding the local maxima of a density function. In the second step, we form a graph based on the mean shift clusters and merge them into larger segments using the normalized cut algorithm. These segments are used to obtain regeneration coverage of the target plot. Results show that, based on validation data from field inventory and terrestrial laser scanning (TLS), our approach correctly estimates up to 70% of regeneration coverage across the plots with different properties, such as tree height and tree species. The proposed method is negatively impacted by the density of the overstory because of decreasing ground point density. In addition, the estimated coverage has a strong relationship with the overstory tree species composition.

  9. Comparison of field and airborne laser scanning based crown cover estimates across land cover types in Kenya

    NASA Astrophysics Data System (ADS)

    Heiskanen, J.; Korhonen, L.; Hietanen, J.; Heikinheimo, V.; Schafer, E.; Pellikka, P. K. E.

    2015-04-01

    Tree crown cover (CC) provides means for the continuous land cover characterization of complex tropical landscapes with multiple land uses and variable degrees of degradation. It is also a key parameter in the international forest definitions that are basis for monitoring global forest cover changes. Recently, airborne laser scanning (ALS) has emerged as a practical method for accurate CC mapping, but ALS derived CC estimates have rarely been assessed with field data in the tropics. Here, our objective was to compare the various field and ALS based CC estimates across multiple land cover types in the Taita Hills, Kenya. The field data was measured from a total of 178 sample plots (0.1 ha) in 2013 and 2014. The most accurate field measurement method, line intersect sampling using Cajanus tube, was used in 37 plots. Other methods included CC estimate based on the tree inventory data (144 plots), crown relascope (43 plots) and hemispherical photography (30 plots). Three ALS data sets, including two scanners and flying heights, were acquired concurrently with the field data collection. According to the results, the first echo cover index (FCI) from ALS data had good agreement with the most accurate field based CC estimates (RMSD 7.1% and 2.7% depending on the area and scan). The agreement with other field based methods was considerably worse. Furthermore, we observed that ALS cover indices were robust between the different scans in the overlapping area. In conclusion, our results suggest that ALS provides a reliable method for continuous CC mapping across tropical land cover types although dense shrub layer and tree-like herbaceous plants can cause overestimation of CC.

  10. Using object-based analysis to derive surface complexity information for improved filtering of airborne laser scanning data

    NASA Astrophysics Data System (ADS)

    Yan, Menglong; Blaschke, Thomas; Tang, Hongzhao; Xiao, Chenchao; Sun, Xian; Zhang, Daobing; Fu, Kun

    2017-03-01

    Airborne laser scanning (ALS) is a technique used to obtain Digital Surface Models (DSM) and Digital Terrain Models (DTM) efficiently, and filtering is the key procedure used to derive DTM from point clouds. Generating seed points is an initial step for most filtering algorithms, whereas existing algorithms usually define a regular window size to generate seed points. This may lead to an inadequate density of seed points, and further introduce error type I, especially in steep terrain and forested areas. In this study, we propose the use of objectbased analysis to derive surface complexity information from ALS datasets, which can then be used to improve seed point generation.We assume that an area is complex if it is composed of many small objects, with no buildings within the area. Using these assumptions, we propose and implement a new segmentation algorithm based on a grid index, which we call the Edge and Slope Restricted Region Growing (ESRGG) algorithm. Surface complexity information is obtained by statistical analysis of the number of objects derived by segmentation in each area. Then, for complex areas, a smaller window size is defined to generate seed points. Experimental results show that the proposed algorithm could greatly improve the filtering results in complex areas, especially in steep terrain and forested areas.

  11. Stochastic gradient boosting classification trees for forest fuel types mapping through airborne laser scanning and IRS LISS-III imagery

    NASA Astrophysics Data System (ADS)

    Chirici, G.; Scotti, R.; Montaghi, A.; Barbati, A.; Cartisano, R.; Lopez, G.; Marchetti, M.; McRoberts, R. E.; Olsson, H.; Corona, P.

    2013-12-01

    This paper presents an application of Airborne Laser Scanning (ALS) data in conjunction with an IRS LISS-III image for mapping forest fuel types. For two study areas of 165 km2 and 487 km2 in Sicily (Italy), 16,761 plots of size 30-m × 30-m were distributed using a tessellation-based stratified sampling scheme. ALS metrics and spectral signatures from IRS extracted for each plot were used as predictors to classify forest fuel types observed and identified by photointerpretation and fieldwork. Following use of traditional parametric methods that produced unsatisfactory results, three non-parametric classification approaches were tested: (i) classification and regression tree (CART), (ii) the CART bagging method called Random Forests, and (iii) the CART bagging/boosting stochastic gradient boosting (SGB) approach. This contribution summarizes previous experiences using ALS data for estimating forest variables useful for fire management in general and for fuel type mapping, in particular. It summarizes characteristics of classification and regression trees, presents the pre-processing operation, the classification algorithms, and the achieved results. The results demonstrated superiority of the SGB method with overall accuracy of 84%. The most relevant ALS metric was canopy cover, defined as the percent of non-ground returns. Other relevant metrics included the spectral information from IRS and several other ALS metrics such as percentiles of the height distribution, the mean height of all returns, and the number of returns.

  12. The use of airborne laser scanning to develop a pixel-based stratification for a verified carbon offset project

    PubMed Central

    2011-01-01

    Background The voluntary carbon market is a new and growing market that is increasingly important to consider in managing forestland. Monitoring, reporting, and verifying carbon stocks and fluxes at a project level is the single largest direct cost of a forest carbon offset project. There are now many methods for estimating forest stocks with high accuracy that use both Airborne Laser Scanning (ALS) and high-resolution optical remote sensing data. However, many of these methods are not appropriate for use under existing carbon offset standards and most have not been field tested. Results This paper presents a pixel-based forest stratification method that uses both ALS and optical remote sensing data to optimally partition the variability across an ~10,000 ha forest ownership in Mendocino County, CA, USA. This new stratification approach improved the accuracy of the forest inventory, reduced the cost of field-based inventory, and provides a powerful tool for future management planning. This approach also details a method of determining the optimum pixel size to best partition a forest. Conclusions The use of ALS and optical remote sensing data can help reduce the cost of field inventory and can help to locate areas that need the most intensive inventory effort. This pixel-based stratification method may provide a cost-effective approach to reducing inventory costs over larger areas when the remote sensing data acquisition costs can be kept low on a per acre basis. PMID:22004847

  13. Airborne laser scanning for forest health status assessment and radiative transfer modelling

    NASA Astrophysics Data System (ADS)

    Novotny, Jan; Zemek, Frantisek; Pikl, Miroslav; Janoutova, Ruzena

    2013-04-01

    Structural parameters of forest stands/ecosystems are an important complementary source of information to spectral signatures obtained from airborne imaging spectroscopy when quantitative assessment of forest stands are in the focus, such as estimation of forest biomass, biochemical properties (e.g. chlorophyll /water content), etc. The parameterization of radiative transfer (RT) models used in latter case requires three-dimensional spatial distribution of green foliage and woody biomass. Airborne LiDAR data acquired over forest sites bears these kinds of 3D information. The main objective of the study was to compare the results from several approaches to interpolation of digital elevation model (DEM) and digital surface model (DSM). We worked with airborne LiDAR data with different density (TopEye Mk II 1,064nm instrument, 1-5 points/m2) acquired over the Norway spruce forests situated in the Beskydy Mountains, the Czech Republic. Three different interpolation algorithms with increasing complexity were tested: i/Nearest neighbour approach implemented in the BCAL software package (Idaho Univ.); ii/Averaging and linear interpolation techniques used in the OPALS software (Vienna Univ. of Technology); iii/Active contour technique implemented in the TreeVis software (Univ. of Freiburg). We defined two spatial resolutions for the resulting coupled raster DEMs and DSMs outputs: 0.4 m and 1 m, calculated by each algorithm. The grids correspond to the same spatial resolutions of hyperspectral imagery data for which the DEMs were used in a/geometrical correction and b/building a complex tree models for radiative transfer modelling. We applied two types of analyses when comparing between results from the different interpolations/raster resolution: 1/calculated DEM or DSM between themselves; 2/comparison with field data: DEM with measurements from referential GPS, DSM - field tree alometric measurements, where tree height was calculated as DSM-DEM. The results of the analyses

  14. Generating an optimal DTM from airborne laser scanning data for landslide mapping in a tropical forest environment

    NASA Astrophysics Data System (ADS)

    Razak, Khamarrul Azahari; Santangelo, Michele; Van Westen, Cees J.; Straatsma, Menno W.; de Jong, Steven M.

    2013-05-01

    Landslide inventory maps are fundamental for assessing landslide susceptibility, hazard, and risk. In tropical mountainous environments, mapping landslides is difficult as rapid and dense vegetation growth obscures landslides soon after their occurrence. Airborne laser scanning (ALS) data have been used to construct the digital terrain model (DTM) under dense vegetation, but its reliability for landslide recognition in the tropics remains surprisingly unknown. This study evaluates the suitability of ALS for generating an optimal DTM for mapping landslides in the Cameron Highlands, Malaysia. For the bare-earth extraction, we used hierarchical robust filtering algorithm and a parameterization with three sequential filtering steps. After each filtering step, four interpolations techniques were applied, namely: (i) the linear prediction derived from the SCOP++ (SCP), (ii) the inverse distance weighting (IDW), (iii) the natural neighbor (NEN) and (iv) the topo-to-raster (T2R). We assessed the quality of 12 DTMs in two ways: (1) with respect to 448 field-measured terrain heights and (2) based on the interpretability of landslides. The lowest root-mean-square error (RMSE) was 0.89 m across the landscape using three filtering steps and linear prediction as interpolation method. However, we found that a less stringent DTM filtering unveiled more diagnostic micro-morphological features, but also retained some of vegetation. Hence, a combination of filtering steps is required for optimal landslide interpretation, especially in forested mountainous areas. IDW was favored as the interpolation technique because it combined computational times more reasonably without adding artifacts to the DTM than T2R and NEN, which performed relatively well in the first and second filtering steps, respectively. The laser point density and the resulting ground point density after filtering are key parameters for producing a DTM applicable to landslide identification. The results showed that the

  15. Detection of harvested trees in forests from repeated high density airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Pietrzyk, P. J.; Lindenbergh, R. C.

    2014-05-01

    Identification of harvested and fallen trees is a prerequisite for the detection and measurement of changes in forests. This paper presents a three step approach to monitor harvested and fallen trees based on direct comparison of repeated high density airborne LIDAR data. In a first step differences between data sets are obtained from a point to point comparison, such that the data can be reduced to the deviating points only. Secondly, the resulting points are clustered into spatially connected regions using region growing. Finally, individual trees are extracted from the clusters by analysing their relative proximity and by analysing geometric properties of points in the clusters. Two data sets, acquired at a four year interval and covering a forest with mainly deciduous trees, are compared. First results show that most points relating to a change can be extracted and that clustering of these with region growing enables us to efficiently separate harvested and fallen trees from the remaining trees. Grouped harvested trees could not be separated using the region growing approach due to touching crowns. Segmentation of these using spectral clustering however identified individual regions well, but the results depend mainly on the pre-defined number of clusters. Crowns of grouped trees can be therefore separated if the number of trees is known.

  16. Mapping tree health using airborne laser scans and hyperspectral imagery: a case study for a floodplain eucalypt forest

    NASA Astrophysics Data System (ADS)

    Shendryk, Iurii; Tulbure, Mirela; Broich, Mark; McGrath, Andrew; Alexandrov, Sergey; Keith, David

    2016-04-01

    Airborne laser scanning (ALS) and hyperspectral imaging (HSI) are two complementary remote sensing technologies that provide comprehensive structural and spectral characteristics of forests over large areas. In this study we developed two algorithms: one for individual tree delineation utilizing ALS and the other utilizing ALS and HSI to characterize health of delineated trees in a structurally complex floodplain eucalypt forest. We conducted experiments in the largest eucalypt, river red gum forest in the world, located in the south-east of Australia that experienced severe dieback over the past six decades. For detection of individual trees from ALS we developed a novel bottom-up approach based on Euclidean distance clustering to detect tree trunks and random walks segmentation to further delineate tree crowns. Overall, our algorithm was able to detect 67% of tree trunks with diameter larger than 13 cm. We assessed the accuracy of tree delineations in terms of crown height and width, with correct delineation of 68% of tree crowns. The increase in ALS point density from ~12 to ~24 points/m2 resulted in tree trunk detection and crown delineation increase of 11% and 13%, respectively. Trees with incorrectly delineated crowns were generally attributed to areas with high tree density along water courses. The accurate delineation of trees allowed us to classify the health of this forest using machine learning and field-measured tree crown dieback and transparency ratios, which were good predictors of tree health in this forest. ALS and HSI derived indices were used as predictor variables to train and test object-oriented random forest classifier. Returned pulse width, intensity and density related ALS indices were the most important predictors in the tree health classifications. At the forest level in terms of tree crown dieback, 77% of trees were classified as healthy, 14% as declining and 9% as dying or dead with 81% mapping accuracy. Similarly, in terms of tree

  17. Mapping Land Cover in the Taita Hills, se Kenya, Using Airborne Laser Scanning and Imaging Spectroscopy Data Fusion

    NASA Astrophysics Data System (ADS)

    Piiroinen, R.; Heiskanen, J.; Maeda, E.; Hurskainen, P.; Hietanen, J.; Pellikka, P.

    2015-04-01

    The Taita Hills, located in south-eastern Kenya, is one of the world's biodiversity hotspots. Despite the recognized ecological importance of this region, the landscape has been heavily fragmented due to hundreds of years of human activity. Most of the natural vegetation has been converted for agroforestry, croplands and exotic forest plantations, resulting in a very heterogeneous landscape. Given this complex agro-ecological context, characterizing land cover using traditional remote sensing methods is extremely challenging. The objective of this study was to map land cover in a selected area of the Taita Hills using data fusion of airborne laser scanning (ALS) and imaging spectroscopy (IS) data. Land Cover Classification System (LCCS) was used to derive land cover nomenclature, while the height and percentage cover classifiers were used to create objective definitions for the classes. Simultaneous ALS and IS data were acquired over a 10 km x 10 km area in February 2013 of which 1 km x 8 km test site was selected. The ALS data had mean pulse density of 9.6 pulses/m2, while the IS data had spatial resolution of 1 m and spectral resolution of 4.5-5 nm in the 400-1000 nm spectral range. Both IS and ALS data were geometrically co-registered and IS data processed to at-surface reflectance. While IS data is suitable for determining land cover types based on their spectral properties, the advantage of ALS data is the derivation of vegetation structural parameters, such as tree height and crown cover, which are crucial in the LCCS nomenclature. Geographic object-based image analysis (GEOBIA) was used for segmentation and classification at two scales. The benefits of GEOBIA and ALS/IS data fusion for characterizing heterogeneous landscape were assessed, and ALS and IS data were considered complementary. GEOBIA was found useful in implementing the LCCS based classification, which would be difficult to map using pixel-based methods.

  18. Airborne and Terrestrial Laser Scanning Activities at UNAVCO: From GeoEarthScope to INTERFACE and Beyond

    NASA Astrophysics Data System (ADS)

    Phillips, D. A.; Jackson, M. E.; Meertens, C. M.; Miller, M. M.

    2009-05-01

    UNAVCO leads and supports airborne and terrestrial laser scanning (ALS and TLS) activities in support of a wide range of earth science applications. UNAVCO acquired nearly 6,000 km2 of high resolution ALS data as part of GeoEarthScope, a component of the EarthScope Facility construction project funded by the National Science Foundation. GeoEarthScope ALS targets in most cases were 1- to 2-km wide corridors centered along active faults including the San Andreas, Hayward, Calaveras, Maacama, Green Valley, Little Salmon, Elsinore, San Cayetano, Garlock, Calico, Lenwood, Blackwater, Helendale, Panamint Valley, Ash Hill, Owens Valley, Death Valley-Fish Lake Valley, Wasatch, Teton, Denali and Totschunda faults. Acquisitions were planned and conducted based on community recommendations with respect to target identification and data collection practices. Particular care was taken to ensure the highest data quality possible within scope and budget, with special considerations given to effective ground point density and geodetic control. Data products are freely available from http://opentopography.org. TLS projects include numerous investigations in polar regions, such as the first TLS survey of the lava lake at Mount Erebus, Antarctica, in January 2009, and activities related to INTERFACE (INTERdisciplinary alliance for digital Field data ACquisition and Exploration), a Collaborative project currently funded by NSF and managed at UNAVCO which includes specialized TLS data processing and visualization software tools developed specifically for geoscience applications. We will present an overview of ALS and TLS project highlights; resources for data collection, accessibility and analysis; and potential use of these data for scientific research and as a framework for future endeavors.

  19. Black-backed woodpecker habitat suitability mapping using conifer snag basal area estimated from airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Casas Planes, Á.; Garcia, M.; Siegel, R.; Koltunov, A.; Ramirez, C.; Ustin, S.

    2015-12-01

    Occupancy and habitat suitability models for snag-dependent wildlife species are commonly defined as a function of snag basal area. Although critical for predicting or assessing habitat suitability, spatially distributed estimates of snag basal area are not generally available across landscapes at spatial scales relevant for conservation planning. This study evaluates the use of airborne laser scanning (ALS) to 1) identify individual conifer snags and map their basal area across a recently burned forest, and 2) map habitat suitability for a wildlife species known to be dependent on snag basal area, specifically the black-backed woodpecker (Picoides arcticus). This study focuses on the Rim Fire, a megafire that took place in 2013 in the Sierra Nevada Mountains of California, creating large patches of medium- and high-severity burned forest. We use forest inventory plots, single-tree ALS-derived metrics and Gaussian processes classification and regression to identify conifer snags and estimate their stem diameter and basal area. Then, we use the results to map habitat suitability for the black-backed woodpecker using thresholds for conifer basal area from a previously published habitat suitability model. Local maxima detection and watershed segmentation algorithms resulted in 75% detection of trees with stem diameter larger than 30 cm. Snags are identified with an overall accuracy of 91.8 % and conifer snags are identified with an overall accuracy of 84.8 %. Finally, Gaussian process regression reliably estimated stem diameter (R2 = 0.8) using height and crown area. This work provides a fast and efficient methodology to characterize the extent of a burned forest at the tree level and a critical tool for early wildlife assessment in post-fire forest management and biodiversity conservation.

  20. Monitoring gully change: A comparison of airborne and terrestrial laser scanning using a case study from Aratula, Queensland

    NASA Astrophysics Data System (ADS)

    Goodwin, Nicholas R.; Armston, John D.; Muir, Jasmine; Stiller, Issac

    2017-04-01

    Airborne laser scanning (ALS) and terrestrial laser scanning (TLS) technologies capture spatially detailed estimates of surface topography and when collected multi-temporally can be used to assess geomorphic change. The sensitivity and repeatability of ALS measurements to characterise geomorphic change in topographically complex environments such as gullies; however, remains an area lacking quantitative research. In this study, we captured coincident ALS and TLS datasets to assess their ability and synergies to detect geomorphic change for a gully located in Aratula, southeast Queensland, Australia. We initially used the higher spatial density and ranging accuracy of TLS to provide an assessment of the Digital Elevation Models (DEM) derived from ALS within a gully environment. Results indicated mean residual errors of 0.13 and 0.09 m along with standard deviation (SD) of residual errors of 0.20 and 0.16 m using pixel sizes of 0.5 and 1.0 m, respectively. The positive mean residual errors confirm that TLS data consistently detected deeper sections of the gully than ALS. We also compared the repeatability of ALS and TLS for characterising gully morphology. This indicated that the sensitivity to detect change using ALS is substantially lower than TLS, as expected, and that the ALS survey characteristics influence the ability to detect change. Notably, we found that using one ALS transect (mean density of 5 points / m2) as opposed to three transects increased the SD of residual error by approximately 30%. The supplied classification of ALS ground points was also demonstrated to misclassify gully features as non-ground, with minimum elevation filtering found to provide a more accurate DEM of the gully. The number and placement of terrestrial laser scans were also found to influence the derived DEMs. Furthermore, we applied change detection using two ALS data captures over a four year period and four TLS field surveys over an eight month period. This demonstrated that

  1. Airborne Laser Scanning (ALS) point cloud ground filtering for area of an active landslide (Doren, Western Austria)

    NASA Astrophysics Data System (ADS)

    Brodić, Nenad; Cvijetinović, Željko; Milenković, Milutin; Dorninger, Peter; Mitrović, Momir

    2014-05-01

    Ground filtering of point cloud is the primary step required for Digital Terrain Model (DTM) generation. The procedure is especially interesting for forested areas, since LiDAR systems can measure terrain elevation under vegetation cover with a high level of penetration. This work analyzes the potential of ALS data ground filtering for area of an active landslide. The results of ALS filtering, for example, may improve geomorphological and motion-detection studies. ALS data was collected during flight campaign 2011 under leaf-off conditions for Doren region, Vorarlberg, Western Austria. In this area, non-ground objects are mostly low vegetation such as shrubs, small trees etc. The vegetation is more dense in lower part of the landslide where erosion is smaller. Vegetation points can be removed based on the hypothesis that these are significantly higher than their neighboring points. However, in case of steep terrain, ground points may have the same heights as vegetation points, and thus, local slope should be considered. Also, if terrain roughness increases, the classification may become even more complex. Software system OPALS (Orientation and Processing of Airborne Laser Scanning data, Vienna University of Technology) was used for processing the ALS data. Labeling ground points has been made using physical and geometrical attributes (parameters) of ALS points. Also additional attributes were calculated in order to improve extraction. Since bare ground surface is usually smooth and continuous unlike vegetation, standard deviation of local elevations was used as roughness measure to differentiate these surfaces. EchoRatio (ER) was adopted as a measure of surface penetrability, while number of echoes and differentiation between echoes (EchoNumber) were also deployed in filtering. Since the ground points are measurements from bare-earth that are usually the lowest surface features in a local area, normalized height was defined as a rank of neighboring points

  2. Object-Based Point Cloud Analysis of Full-Waveform Airborne Laser Scanning Data for Urban Vegetation Classification.

    PubMed

    Rutzinger, Martin; Höfle, Bernhard; Hollaus, Markus; Pfeifer, Norbert

    2008-08-04

    Airborne laser scanning (ALS) is a remote sensing technique well-suited for 3D vegetation mapping and structure characterization because the emitted laser pulses are able to penetrate small gaps in the vegetation canopy. The backscattered echoes from the foliage, woody vegetation, the terrain, and other objects are detected, leading to a cloud of points. Higher echo densities (> 20 echoes/m2) and additional classification variables from full-waveform (FWF) ALS data, namely echo amplitude, echo width and information on multiple echoes from one shot, offer new possibilities in classifying the ALS point cloud. Currently FWF sensor information is hardly used for classification purposes. This contribution presents an object-based point cloud analysis (OBPA) approach, combining segmentation and classification of the 3D FWF ALS points designed to detect tall vegetation in urban environments. The definition tall vegetation includes trees and shrubs, but excludes grassland and herbage. In the applied procedure FWF ALS echoes are segmented by a seeded region growing procedure. All echoes sorted descending by their surface roughness are used as seed points. Segments are grown based on echo width homogeneity. Next, segment statistics (mean, standard deviation, and coefficient of variation) are calculated by aggregating echo features such as amplitude and surface roughness. For classification a rule base is derived automatically from a training area using a statistical classification tree. To demonstrate our method we present data of three sites with around 500,000 echoes each. The accuracy of the classified vegetation segments is evaluated for two independent validation sites. In a point-wise error assessment, where the classification is compared with manually classified 3D points, completeness and correctness better than 90% are reached for the validation sites. In comparison to many other algorithms the proposed 3D point classification works on the original measurements

  3. Object-Based Point Cloud Analysis of Full-Waveform Airborne Laser Scanning Data for Urban Vegetation Classification

    PubMed Central

    Rutzinger, Martin; Höfle, Bernhard; Hollaus, Markus; Pfeifer, Norbert

    2008-01-01

    Airborne laser scanning (ALS) is a remote sensing technique well-suited for 3D vegetation mapping and structure characterization because the emitted laser pulses are able to penetrate small gaps in the vegetation canopy. The backscattered echoes from the foliage, woody vegetation, the terrain, and other objects are detected, leading to a cloud of points. Higher echo densities (>20 echoes/m2) and additional classification variables from full-waveform (FWF) ALS data, namely echo amplitude, echo width and information on multiple echoes from one shot, offer new possibilities in classifying the ALS point cloud. Currently FWF sensor information is hardly used for classification purposes. This contribution presents an object-based point cloud analysis (OBPA) approach, combining segmentation and classification of the 3D FWF ALS points designed to detect tall vegetation in urban environments. The definition tall vegetation includes trees and shrubs, but excludes grassland and herbage. In the applied procedure FWF ALS echoes are segmented by a seeded region growing procedure. All echoes sorted descending by their surface roughness are used as seed points. Segments are grown based on echo width homogeneity. Next, segment statistics (mean, standard deviation, and coefficient of variation) are calculated by aggregating echo features such as amplitude and surface roughness. For classification a rule base is derived automatically from a training area using a statistical classification tree. To demonstrate our method we present data of three sites with around 500,000 echoes each. The accuracy of the classified vegetation segments is evaluated for two independent validation sites. In a point-wise error assessment, where the classification is compared with manually classified 3D points, completeness and correctness better than 90% are reached for the validation sites. In comparison to many other algorithms the proposed 3D point classification works on the original measurements

  4. Application of Airborne Hydrographic Laser Scanning for Mapping Shallow Water Riverine Environments in the Pacific Northwest, United States

    NASA Astrophysics Data System (ADS)

    Cooper, C.; Nayegandhi, A.; Faux, R.

    2013-12-01

    Small-footprint, green wavelength airborne LiDAR systems can provide seamless topography across the land-water interface at very high spatial resolution. These data have the potential to improve floodplain modeling, fisheries habitat assessments, stream restoration efforts, and other applications by continuously mapping shallow water depths that are difficult or impossible to measure using traditional ground-based or water-borne survey techniques. WSI (Corvallis, Oregon) in collaboration with Dewberry, (Tampa, Florida) and Riegl (Orlando, Florida), deployed the Riegl VQ-820-G hydrographic airborne laser scanner to map riverine and lacustrine environments from Oregon to Minnesota. Discussion will focus on the ability to accurately map depth and underwater structure, as well as riparian vegetation and terrain under different conditions. Results indicate that depth penetration varies with both water (i.e. clarity and surface conditions) and bottom conditions (i.e. substrate, depth, and landform). Depth penetration was typically limited to 1 Secchi depth or less across selected project areas. As an example, the green LiDAR system effectively mapped 83% of a shallow water river system, the Sandy River, with typical depths ranging from 0-2.5 meters. WSI will show quantitative comparisons of Green LiDAR surveys against more traditional methods such as rod or sonar surveys. WSI will also discuss advantages and limitations of Green LiDAR surveys for bathymetric modeling including survey accuracy, density, and efficiency along with data processing challenges not inherent with traditional NIR LiDAR processing.

  5. Comparing the above-ground component biomass estimates of western junipers using airborne and full-waveform terrestrial laser scanning data

    NASA Astrophysics Data System (ADS)

    Shrestha, R.; Glenn, N. F.; Spaete, L.; Hardegree, S. P.

    2012-12-01

    With the rapid expansion into shrub steppe and grassland ecosystems over the last century, western juniper (Juniperus occidentalis var. occidentalis Hook) is becoming a major component of the regional carbon pool in the Intermountain West. Understanding how biomass is allocated across individual tree components is necessary to understand the uncertainties in biomass estimates and more accurately quantify biomass and carbon dynamics in these ecosystems. Estimates of component biomass are also important for canopy fuel load assessment and predicting rangeland fire behavior. Airborne LiDAR can capture vegetation structure over larger scales, but the high crown penetration and sampling density of terrestrial laser scanner (TLS) instruments can better capture tree components. In this study, we assessed the ability of airborne LiDAR to estimate biomass of tree components of western juniper with validation data from field measured tees and a full-waveform TLS. Sixteen juniper trees (height range 1.5-10 m) were randomly selected using a double sampling strategy from different height classes in the Reynolds Creek Experimental Watershed in the Owyhee Mountains, southwestern Idaho, USA. Each tree was scanned with a full-waveform TLS, and the dry biomass of each component (foliage, branches and main stem) were measured by destructive harvesting of the trees. We compare the allometric relationships of biomass estimates of the tree components obtained from field-measured trees and TLS-based estimates with the estimates from discrete-return airborne-LiDAR based estimates.

  6. Potential of Full Waveform Airborne Laser Scanning Data for Urban Area Classification - Transfer of Classification Approaches Between Missions

    NASA Astrophysics Data System (ADS)

    Tran, G.; Nguyen, D.; Milenkovic, M.; Pfeifer, N.

    2015-04-01

    Full-waveform (FWF) LiDAR (Light Detection and Ranging) systems have their advantage in recording the entire backscattered signal of each emitted laser pulse compared to conventional airborne discrete-return laser scanner systems. The FWF systems can provide point clouds which contain extra attributes like amplitude and echo width, etc. In this study, a FWF data collected in 2010 for Eisenstadt, a city in the eastern part of Austria was used to classify four main classes: buildings, trees, waterbody and ground by employing a decision tree. Point density, echo ratio, echo width, normalised digital surface model and point cloud roughness are the main inputs for classification. The accuracy of the final results, correctness and completeness measures, were assessed by comparison of the classified output to a knowledge-based labelling of the points. Completeness and correctness between 90% and 97% was reached, depending on the class. While such results and methods were presented before, we are investigating additionally the transferability of the classification method (features, thresholds ...) to another urban FWF lidar point cloud. Our conclusions are that from the features used, only echo width requires new thresholds. A data-driven adaptation of thresholds is suggested.

  7. Airborne laser scan data: a valuable tool with which to infer weather radar partial beam blockage in urban environments

    NASA Astrophysics Data System (ADS)

    Cremonini, Roberto; Moisseev, Dmitri; Chandrasekar, Venkatachalam

    2016-10-01

    High-spatial-resolution weather radar observations are of primary relevance for hydrological applications in urban areas. However, when weather radars are located within metropolitan areas, partial beam blockages and clutter by buildings can seriously affect the observations. Standard simulations with simple beam propagation models and digital elevation models (DEMs) are usually not able to evaluate buildings' contribution to partial beam blockages. In recent years airborne laser scanners (ALSs) have evolved to the state-of-the-art technique for topographic data acquisition. Providing small footprint diameters (10-30 cm), ALS data allow accurate reconstruction of buildings and forest canopy heights. Analyzing the three weather C-band radars located in the metropolitan area of Helsinki, Finland, the present study investigates the benefits of using ALS data for quantitative estimations of partial beam blockages. The results obtained applying beam standard propagation models are compared with stratiform 24 h rainfall accumulation to evaluate the effects of partial beam blockages due to constructions and trees. To provide a physical interpretation of the results, the detailed analysis of beam occultations is achieved by open spatial data sets and open-source geographic information systems.

  8. A prospectus on airborne laser mapping systems

    NASA Technical Reports Server (NTRS)

    Link, L. E.; Krabill, W. B.; Swift, R. N.

    1983-01-01

    Airborne laser systems have demonstrated enormous potential for topographic and bathymetric mapping. Both profiling and scanning systems have been evaluated for terrain elevation mapping, stream valley cross-section determination, and nearshore bottom profiling. Performance of the laser systems has been impressive and for some applications matches current operational accuracy requirements. Determining the position of individual laser measurements remains a constraint for most applications. Laser technology constrains some terrain and bathymetric applications, particularly for water penetration and frequency of measurements for high-spatial resolution over large areas.

  9. Airborne Laser/GPS Mapping of Beaches

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Swift, R. N.; Fredrick, E. B.; Manizade, S. S.; Martin, C. F.; Sonntag, J. G.; Duffy, Mark

    1999-01-01

    Results are presented from topographic surveys of the Assateague National Seashore Park using recently developed airborne laser and Global Positioning System (GPS) technology. During November, 1995, and again in May, 1996, the NASA Arctic Ice Mapping (AIM) group from the NASA Goddard Space Flight Center's Wallops Flight Facility conducted surveys as a part of technology enhancement activities or warm-up missions prior to conducting elevation measurements of the Greenland Ice Sheet as part of NASA's Global Climate Change program. The resulting data are compared to surface surveys using standard techniques. The goal of these projects is to make these measurements to an accuracy of 10 cm. The measurements were made from NASA's 4-engine P-3 Orion aircraft using the Airborne Topographic Mapper (ATM), a scanning laser system. The necessary high accuracy vertical as well as horizontal positioning are provided by Global Positioning System (GPS) receivers located both on board the aircraft and at a fixed site at Wallops Island.

  10. Airborne Visible Laser Optical Communications Program (AVLOC)

    NASA Technical Reports Server (NTRS)

    Ward, J. H.

    1975-01-01

    The design, development, and operation of airborne and ground-based laser communications and laser radar hardware is described in support of the Airborne Visible Laser Optical Communication program. The major emphasis is placed on the development of a highly flexible test bed for the evaluation of laser communications systems techniques and components in an operational environment.

  11. The relation between Arctic sea ice surface elevation and draft: A case study using coincident AUV sonar and airborne scanning laser

    NASA Astrophysics Data System (ADS)

    Doble, Martin J.; Skourup, Henriette; Wadhams, Peter; Geiger, Cathleen A.

    2011-08-01

    Data are presented from a survey by airborne scanning laser profilometer and an AUV-mounted, upward looking swath sonar in the spring Beaufort Sea. The air-snow (surface elevation) and water-ice (draft) surfaces were mapped at 1 × 1 m resolution over a 300 × 300 m area. Data were separated into level and deformed ice fractions using the surface roughness of the sonar data. The relation (R = d/f) between draft, d, and surface elevation, f, was then examined. Correlation between top and bottom surfaces was essentially zero at full resolution, requiring averaging over patches of at least 11 m diameter to constrain the relation largely because of the significant error (˜15 cm) of the laser instrument. Level ice points were concentrated in two core regions, corresponding to level FY ice and refrozen leads, with variations in R attributed primarily to positive snow thickness variability. Deformed ice displayed a more diffuse "cloud," with draft having a more important role in determining R because of wider deformed features underwater. Averaging over footprints similar to satellite altimeters showed the mean surface elevation (typical of ICESat) to be stable with averaging scale, with R = 3.4 (level) and R = 4.2 (deformed). The "minimum elevation within a footprint" characteristic reported for CryoSat was less stable, significantly overestimating R for level ice (R > 5) and deformed ice (R > 6). The mean draft difference between measurements and isostasy suggests 70 m as an isostatic length scale for level ice. The isostatic scale for deformed ice appears to be longer than accessible with these data (>300 m).

  12. Aerial Orthophoto and Airborne Laser Scanning as Monitoring Tools for Land Cover Dynamics: A Case Study from the Milicz Forest District (Poland)

    NASA Astrophysics Data System (ADS)

    Szostak, Marta; Wezyk, Piotr; Tompalski, Piotr

    2013-04-01

    The paper presents the results from the study concerning the application of airborne laser scanning (ALS) data and derived raster products like the digital surface model (DSM) and the digital terrain model (DTM) for the assessment of the degree of change of the land use based on the forest succession example. Simultaneously, an automated method of ALS data processing was developed based on the normalized (nDSM) and cadastral GIS information. Besides delivering precise information on forest succession, ALS technology is an excellent tool for time-changes spatial analyses. Usage of the ALS data can support the image interpretation process decreasing the subjectivity of the operator. In parallel, a manual vectorization and object classification (object-based image analysis—OBIA) were performed; both based on aerial orthophoto and ALS data. By using integrated ALS point clouds and digital aerial images, one can obtain fast OBIA processing and the determination of areas where the land cover has changed. The Milicz District (central west part of Poland) was chosen as the test site where ALS was to be performed in 2007, together with the digital aerial photos (Vexcel camera; pixel 0.15 m; CIR). The aerial photos were then processed to a CIR orthophoto. The area of study consisted of 68 private parcels (some of them were abandoned; 68.57 ha; scanned cadastral maps from the local survey office; land use information) in the direct neighbourhood of the State Forest, on which a forest succession could often be observed. The operator vectorized forest (trees and shrubs) succession areas on the 2D CIR orthophoto. They were then compared with the results from the OBIA and GIS analysis, based on the normalized digital surface model. The results showed that areas with high vegetation cover were three times larger than the official land cover database (cadastral maps).

  13. Aerial Orthophoto and Airborne Laser Scanning as Monitoring Tools for Land Cover Dynamics: A Case Study from the Milicz Forest District (Poland)

    NASA Astrophysics Data System (ADS)

    Szostak, Marta; Wezyk, Piotr; Tompalski, Piotr

    2014-06-01

    The paper presents the results from the study concerning the application of airborne laser scanning (ALS) data and derived raster products like the digital surface model (DSM) and the digital terrain model (DTM) for the assessment of the degree of change of the land use based on the forest succession example. Simultaneously, an automated method of ALS data processing was developed based on the normalized (nDSM) and cadastral GIS information. Besides delivering precise information on forest succession, ALS technology is an excellent tool for time-changes spatial analyses. Usage of the ALS data can support the image interpretation process decreasing the subjectivity of the operator. In parallel, a manual vectorization and object classification (object-based image analysis—OBIA) were performed; both based on aerial orthophoto and ALS data. By using integrated ALS point clouds and digital aerial images, one can obtain fast OBIA processing and the determination of areas where the land cover has changed. The Milicz District (central west part of Poland) was chosen as the test site where ALS was to be performed in 2007, together with the digital aerial photos (Vexcel camera; pixel 0.15 m; CIR). The aerial photos were then processed to a CIR orthophoto. The area of study consisted of 68 private parcels (some of them were abandoned; 68.57 ha; scanned cadastral maps from the local survey office; land use information) in the direct neighbourhood of the State Forest, on which a forest succession could often be observed. The operator vectorized forest (trees and shrubs) succession areas on the 2D CIR orthophoto. They were then compared with the results from the OBIA and GIS analysis, based on the normalized digital surface model. The results showed that areas with high vegetation cover were three times larger than the official land cover database (cadastral maps).

  14. Determination of the spatial structure of vegetation on the repository of the mine "Fryderyk" in Tarnowskie Góry, based on airborne laser scanning from the ISOK project and digital orthophotomaps

    NASA Astrophysics Data System (ADS)

    Szostak, Marta; Wężyk, Piotr; Pająk, Marek; Haryło, Paweł; Lisańczuk, Marek

    2015-06-01

    The purpose of this study was to determine the spatial structure of vegetation on the repository of the mine "Fryderyk" in Tarnowskie Góry. Tested area was located in the Upper Silesian Industrial Region (a large industrial region in Poland). It was a unique refuge habitat - Natura2000; PLH240008. The main aspect of this elaboration was to investigate the possible use of geotechniques and generally available geodata for mapping LULC changes and determining the spatial structure of vegetation. The presented study focuses on the analysis of a spatial structure of vegetation in the research area. This exploration was based on aerial images and orthophotomaps from 1947, 1998, 2003, 2009, 2011 and airborne laser scanning data (2011, ISOK project). Forest succession changes which occurred between 1947 and 2011 were analysed. The selected features of vegetation overgrowing spoil heap "Fryderyk" was determined. The results demonstrated a gradual succession of greenery on soil heap. In 1947, 84% of this area was covered by low vegetation. Tree expansion was proceeding in the westerly and northwest direction. In 2011 this canopy layer covered almost 50% of the research area. Parameters such as height of vegetation, crowns length and cover density were calculated by an airborne laser scanning data. These analyses indicated significant diversity in vertical and horizontal structures of vegetation. The study presents some capacities to use airborne laser scanning for an impartial evaluation of the structure of vegetation.

  15. A Comprehensive Automated 3D Approach for Building Extraction, Reconstruction, and Regularization from Airborne Laser Scanning Point Clouds

    PubMed Central

    Dorninger, Peter; Pfeifer, Norbert

    2008-01-01

    Three dimensional city models are necessary for supporting numerous management applications. For the determination of city models for visualization purposes, several standardized workflows do exist. They are either based on photogrammetry or on LiDAR or on a combination of both data acquisition techniques. However, the automated determination of reliable and highly accurate city models is still a challenging task, requiring a workflow comprising several processing steps. The most relevant are building detection, building outline generation, building modeling, and finally, building quality analysis. Commercial software tools for building modeling require, generally, a high degree of human interaction and most automated approaches described in literature stress the steps of such a workflow individually. In this article, we propose a comprehensive approach for automated determination of 3D city models from airborne acquired point cloud data. It is based on the assumption that individual buildings can be modeled properly by a composition of a set of planar faces. Hence, it is based on a reliable 3D segmentation algorithm, detecting planar faces in a point cloud. This segmentation is of crucial importance for the outline detection and for the modeling approach. We describe the theoretical background, the segmentation algorithm, the outline detection, and the modeling approach, and we present and discuss several actual projects. PMID:27873931

  16. A Comprehensive Automated 3D Approach for Building Extraction, Reconstruction, and Regularization from Airborne Laser Scanning Point Clouds.

    PubMed

    Dorninger, Peter; Pfeifer, Norbert

    2008-11-17

    Three dimensional city models are necessary for supporting numerous management applications. For the determination of city models for visualization purposes, several standardized workflows do exist. They are either based on photogrammetry or on LiDAR or on a combination of both data acquisition techniques. However, the automated determination of reliable and highly accurate city models is still a challenging task, requiring a workflow comprising several processing steps. The most relevant are building detection, building outline generation, building modeling, and finally, building quality analysis. Commercial software tools for building modeling require, generally, a high degree of human interaction and most automated approaches described in literature stress the steps of such a workflow individually. In this article, we propose a comprehensive approach for automated determination of 3D city models from airborne acquired point cloud data. It is based on the assumption that individual buildings can be modeled properly by a composition of a set of planar faces. Hence, it is based on a reliable 3D segmentation algorithm, detecting planar faces in a point cloud. This segmentation is of crucial importance for the outline detection and for the modeling approach. We describe the theoretical background, the segmentation algorithm, the outline detection, and the modeling approach, and we present and discuss several actual projects.

  17. Airborne Laser Scanning Quantification of Disturbances from Hurricanes and Lightning Strikes to Mangrove Forests in Everglades National Park, USA

    PubMed Central

    Zhang, Keqi; Simard, Marc; Ross, Michael; Rivera-Monroy, Victor H.; Houle, Patricia; Ruiz, Pablo; Twilley, Robert R.; Whelan, Kevin R. T.

    2008-01-01

    Airborne light detection and ranging (LIDAR) measurements derived before and after Hurricanes Katrina and Wilma (2005) were used to quantify the impact of hurricanes and lightning strikes on the mangrove forest at two sites in Everglades National Park (ENP). Analysis of LIDAR measurements covering 61 and 68 ha areas of mangrove forest at the Shark River and Broad River sites showed that the proportion of high tree canopy detected by the LIDAR after the 2005 hurricane season decreased significantly due to defoliation and breakage of branches and trunks, while the proportion of low canopy and the ground increased drastically. Tall mangrove forests distant from tidal creeks suffered more damage than lower mangrove forests adjacent to the tidal creeks. The hurricanes created numerous canopy gaps, and the number of gaps per square kilometer increased from about 400∼500 to 4000 after Katrina and Wilma. The total area of gaps in the forest increased from about 1∼2% of the total forest area to 12%. The relative contribution of hurricanes to mangrove forest disturbance in ENP is at least 2 times more than that from lightning strikes. However, hurricanes and lightning strikes disturb the mangrove forest in a related way. Most seedlings in lightning gaps survived the hurricane impact due to the protection of trees surrounding the gaps, and therefore provide an important resource for forest recovery after the hurricane. This research demonstrated that LIDAR is an effective remote sensing tool to quantify the effects of disturbances such as hurricanes and lightning strikes in the mangrove forest. PMID:27879821

  18. Airborne Laser Scanning Quantification of Disturbances from Hurricanes and Lightning Strikes to Mangrove Forests in Everglades National Park, USA.

    PubMed

    Zhang, Keqi; Simard, Marc; Ross, Michael; Rivera-Monroy, Victor H; Houle, Patricia; Ruiz, Pablo; Twilley, Robert R; Whelan, Kevin

    2008-04-01

    Airborne light detection and ranging (LIDAR) measurements derived before and after Hurricanes Katrina and Wilma (2005) were used to quantify the impact of hurricanes and lightning strikes on the mangrove forest at two sites in Everglades National Park (ENP). Analysis of LIDAR measurements covering 61 and 68 ha areas of mangrove forest at the Shark River and Broad River sites showed that the proportion of high tree canopy detected by the LIDAR after the 2005 hurricane season decreased significantly due to defoliation and breakage of branches and trunks, while the proportion of low canopy and the ground increased drastically. Tall mangrove forests distant from tidal creeks suffered more damage than lower mangrove forests adjacent to the tidal creeks. The hurricanes created numerous canopy gaps, and the number of gaps per square kilometer increased from about 400~500 to 4000 after Katrina and Wilma. The total area of gaps in the forest increased from about 1~2% of the total forest area to 12%. The relative contribution of hurricanes to mangrove forest disturbance in ENP is at least 2 times more than that from lightning strikes. However, hurricanes and lightning strikes disturb the mangrove forest in a related way. Most seedlings in lightning gaps survived the hurricane impact due to the protection of trees surrounding the gaps, and therefore provide an important resource for forest recovery after the hurricane. This research demonstrated that LIDAR is an effective remote sensing tool to quantify the effects of disturbances such as hurricanes and lightning strikes in the mangrove forest.

  19. Quantification of Barchan Dune Evolution over Monthly to Interannual Time Scales Using Airborne LIDAR and Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Hoose, M.; Pelletier, J. D.

    2013-12-01

    Barchan dunes are among the most rapidly evolving landforms on Earth, with migration rates of up to 100 m/yr. Despite the central importance of barchan dunes in aeolian geomorphology and the relative ease of quantifying changes in their shape and position, basic questions remain about barchan dune evolution. For example, how does the position of a dune relative to its neighbors affect the evolution of a dune? The presence of a dune influences the air flow around the dune, potentially modifying the evolution of neighboring dunes. Also, a dune may grow in size more rapidly if neighboring dunes are located immediately upwind of the dune, thus providing additional sources of sand for the dune relative to the case of an isolated dune. To address these questions, we quantified the change in the position of 14 dunes, and the sand flux among them, in the Salton Sea dune field over two time scales: 1 month and 3 years. The 1-month change map was created using two TLS surveys completed in the summer of 2013, and the 3-year change map was created using the results of a TLS survey in 2013 and an airborne LIDAR survey from 2010. The PHOENICS Computational Fluid Dynamics solver was used to predict the change in the positions of the dunes and the flux of sand among them. PHOENICS was used to model the shear stress over the dune field using DEM data from the beginning of each interval of study, together with data on the wind profile collected at the study site using a wind tower. The output of PHOENICS was used as input to a shear-stress-dependent aeolian transport formula with the effect of slope on the threshold of entrainment included. Preliminary analyses of the ALSM- and TLS-derived change maps indicate that clustered dunes interact via boundary layer effects to alter the migration and growth rates of their downwind neighbors. Additionally, the effects of subdominant, southeasterly winds were observed in the 1-month change map in the form of sand wedges deposited along the

  20. Use of high resolution Airborne Laser Scanning data for landslide interpretation under mixed forest and tropical rainforest: case study in Barcelonnette, France and Cameron Highlands, Malaysia

    NASA Astrophysics Data System (ADS)

    Azahari Razak, Khamarrul; Straatsma, Menno; van Westen, Cees; Malet, Jean-Philippe; de Jong, Steven M.

    2010-05-01

    Airborne Laser Scanning (ALS) is the state of the art technology for topographic mapping over a wide variety of spatial and temporal scales. It is also a promising technique for identification and mapping of landslides in a forested mountainous landscape. This technology demonstrates the ability to pass through the gaps between forest foliage and record the terrain height under vegetation cover. To date, most of the images either derived from satellite imagery, aerial-photograph or synthetic aperture radar are not appropriate for visual interpretation of landslide features that are covered by dense vegetation. However, it is a necessity to carefully map the landslides in order to understand its processes. This is essential for landslide hazard and risk assessment. This research demonstrates the capabilities of high resolution ALS data to recognize and identify different types of landslides in mixed forest in Barcelonnette, France and tropical rainforest in Cameron Highlands, Malaysia. ALS measurements over the 100-years old forest in Bois Noir catchment were carried out in 2007 and 2009. Both ALS dataset were captured using a Riegl laser scanner. First and last pulse with density of one point per meter square was derived from 2007 ALS dataset, whereas multiple return (of up to five returns) pulse was derived from July 2009 ALS dataset, which consists of 60 points per meter square over forested terrain. Generally, this catchment is highly affected by shallow landslides which mostly occur beneath dense vegetation. It is located in the dry intra-Alpine zone and represented by the climatic of the South French Alps. In the Cameron Highlands, first and last pulse data was captured in 2004 which covers an area of up to 300 kilometres square. Here, the Optech laser scanner was used under the Malaysian national pilot study which has slightly low point density. With precipitation intensity of up to 3000 mm per year over rugged topography and elevations up to 2800 m a

  1. Helios: a Multi-Purpose LIDAR Simulation Framework for Research, Planning and Training of Laser Scanning Operations with Airborne, Ground-Based Mobile and Stationary Platforms

    NASA Astrophysics Data System (ADS)

    Bechtold, S.; Höfle, B.

    2016-06-01

    In many technical domains of modern society, there is a growing demand for fast, precise and automatic acquisition of digital 3D models of a wide variety of physical objects and environments. Laser scanning is a popular and widely used technology to cover this demand, but it is also expensive and complex to use to its full potential. However, there might exist scenarios where the operation of a real laser scanner could be replaced by a computer simulation, in order to save time and costs. This includes scenarios like teaching and training of laser scanning, development of new scanner hardware and scanning methods, or generation of artificial scan data sets to support the development of point cloud processing and analysis algorithms. To test the feasibility of this idea, we have developed a highly flexible laser scanning simulation framework named Heidelberg LiDAR Operations Simulator (HELIOS). HELIOS is implemented as a Java library and split up into a core component and multiple extension modules. Extensible Markup Language (XML) is used to define scanner, platform and scene models and to configure the behaviour of modules. Modules were developed and implemented for (1) loading of simulation assets and configuration (i.e. 3D scene models, scanner definitions, survey descriptions etc.), (2) playback of XML survey descriptions, (3) TLS survey planning (i.e. automatic computation of recommended scanning positions) and (4) interactive real-time 3D visualization of simulated surveys. As a proof of concept, we show the results of two experiments: First, a survey planning test in a scene that was specifically created to evaluate the quality of the survey planning algorithm. Second, a simulated TLS scan of a crop field in a precision farming scenario. The results show that HELIOS fulfills its design goals.

  2. On the integration of Airborne full-waveform laser scanning and optical imagery for Site Detection and Mapping: Monteserico study case

    NASA Astrophysics Data System (ADS)

    Coluzzi, R.; Guariglia, A.; Lacovara, B.; Lasaponara, R.; Masini, N.

    2009-04-01

    This paper analyses the capability of airborne LiDAR derived data in the recognition of archaeological marks. It also evaluates the benefits to integrate them with aerial photos and very high resolution satellite imagery. The selected test site is Monteserico, a medieval village located on a pastureland hill in the North East of Basilicata (Southern Italy). The site, attested by documentary sources beginning from the 12th century, was discovered by aerial survey in 1996 [1] and investigated in 2005 by using QuickBird imagery [2]. The only architectural evidence is a castle, built on the western top of the hill; whereas on the southern side, earthenware, pottery and crumbling building materials, related to the medieval settlement, could be observed. From a geological point of view, the stratigraphic sequence is composed of Subappennine Clays, Monte Marano sands and Irsina conglomerates. Sporadic herbaceous plants grow over the investigated area. For the purpose of this study, a full-waveform laser scanning with a 240.000 Hz frequency was used. The average point density value of dataset is about 30 points/m2. The final product is a 0.30 m Digital Surface Models (DSMs) accurately modelled. To derive the DSM the point cloud of the ALS was filtered and then classified by applying appropriate algorithms. In this way surface relief and archaeological features were surveyed with great detail. The DSM was compared with other remote sensing data source such as oblique and nadiral aerial photos and QuickBird imagery, acquired in different time. In this way it was possible to evaluate, compare each other and overlay the archaeological features recorded from each data source (aerial, satellite and lidar). Lidar data showed some interesting results. In particular, they allowed for identifying and recording differences in height on the ground produced by surface and shallow archaeological remains (the so-called shadow marks). Most of these features are visible also by the optical

  3. Airborne laser sensors and integrated systems

    NASA Astrophysics Data System (ADS)

    Sabatini, Roberto; Richardson, Mark A.; Gardi, Alessandro; Ramasamy, Subramanian

    2015-11-01

    The underlying principles and technologies enabling the design and operation of airborne laser sensors are introduced and a detailed review of state-of-the-art avionic systems for civil and military applications is presented. Airborne lasers including Light Detection and Ranging (LIDAR), Laser Range Finders (LRF), and Laser Weapon Systems (LWS) are extensively used today and new promising technologies are being explored. Most laser systems are active devices that operate in a manner very similar to microwave radars but at much higher frequencies (e.g., LIDAR and LRF). Other devices (e.g., laser target designators and beam-riders) are used to precisely direct Laser Guided Weapons (LGW) against ground targets. The integration of both functions is often encountered in modern military avionics navigation-attack systems. The beneficial effects of airborne lasers including the use of smaller components and remarkable angular resolution have resulted in a host of manned and unmanned aircraft applications. On the other hand, laser sensors performance are much more sensitive to the vagaries of the atmosphere and are thus generally restricted to shorter ranges than microwave systems. Hence it is of paramount importance to analyse the performance of laser sensors and systems in various weather and environmental conditions. Additionally, it is important to define airborne laser safety criteria, since several systems currently in service operate in the near infrared with considerable risk for the naked human eye. Therefore, appropriate methods for predicting and evaluating the performance of infrared laser sensors/systems are presented, taking into account laser safety issues. For aircraft experimental activities with laser systems, it is essential to define test requirements taking into account the specific conditions for operational employment of the systems in the intended scenarios and to verify the performance in realistic environments at the test ranges. To support the

  4. Scanned Laser Illuminator/Receiver

    DTIC Science & Technology

    1976-11-01

    illustrate parallel development of the PIN diode /CCD sensor hybrid and the 100W laser . Al- though a detailed cost analysis for procurement of this large...pmww^^W .m^n.m .,** ■ —ssa^ AFAL-TR-76-184 \\ SCANNED LASER ILLUMINATOR/RECEIVER ^ R. A. Honzik and F. B. Warren ^•Martin Marietta...NUMBER 4. TITLE (and Sublille) SCANNED LASER ILLUMINATOR/RECEIVER 5, TYPE OF REPORT & PERIOD COVERED Final Technical Report Dec 75

  5. Ground extraction from airborne laser data based on wavelet analysis

    NASA Astrophysics Data System (ADS)

    Xu, Liang; Yang, Yan; Jiang, Bowen; Li, Jia

    2007-11-01

    With the advantages of high resolution and accuracy, airborne laser scanning data are widely used in topographic mapping. In order to generate a DTM, measurements from object features such as buildings, vehicles and vegetation have to be classified and removed. However, the automatic extraction of bare earth from point clouds acquired by airborne laser scanning equipment remains a problem in LIDAR data filtering nowadays. In this paper, a filter algorithm based on wavelet analysis is proposed. Relying on the capability of detecting discontinuities of continuous wavelet transform and the feature of multi-resolution analysis, the object points can be removed, while ground data are preserved. In order to evaluate the performance of this approach, we applied it to the data set used in the ISPRS filter test in 2003. 15 samples have been tested by the proposed approach. Results showed that it filtered most of the objects like vegetation and buildings, and extracted a well defined ground model.

  6. Airborne space laser communication system and experiments

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Ming; Zhang, Li-zhong; Meng, Li-Xin

    2015-11-01

    Airborne space laser communication is characterized by its high speed, anti-electromagnetic interference, security, easy to assign. It has broad application in the areas of integrated space-ground communication networking, military communication, anti-electromagnetic communication. This paper introduce the component and APT system of the airborne laser communication system design by Changchun university of science and technology base on characteristic of airborne laser communication and Y12 plan, especially introduce the high communication speed and long distance communication experiment of the system that among two Y12 plans. In the experiment got the aim that the max communication distance 144Km, error 10-6 2.5Gbps - 10-7 1.5Gbps capture probability 97%, average capture time 20s. The experiment proving the adaptability of the APT and the high speed long distance communication.

  7. National center for airborne laser mapping proposed

    NASA Astrophysics Data System (ADS)

    Carter, Bill; Shrestha, Ramesh L.; Dietrich, Bill

    Researchers from universities, U.S. government agencies, U.S. national laboratories, and private industry met in the spring to learn about the current capabilities of Airborne Laser Swath Mapping (ALSM), share their experiences in using the technology for a wide variety of research applications, outline research that would be made possible by research-grade ALSM data, and discuss the proposed operation and management of the brand new National Center for Airborne Laser Mapping (NCALM).The workshop successfully identified a community of researchers with common interests in the advancement and use of ALSM—a community which strongly supports the immediate establishment of the NCALM.

  8. Laser Imaging of Airborne Acoustic Emission by Nonlinear Defects

    NASA Astrophysics Data System (ADS)

    Solodov, Igor; Döring, Daniel; Busse, Gerd

    2008-06-01

    Strongly nonlinear vibrations of near-surface fractured defects driven by an elastic wave radiate acoustic energy into adjacent air in a wide frequency range. The variations of pressure in the emitted airborne waves change the refractive index of air thus providing an acoustooptic interaction with a collimated laser beam. Such an air-coupled vibrometry (ACV) is proposed for detecting and imaging of acoustic radiation of nonlinear spectral components by cracked defects. The photoelastic relation in air is used to derive induced phase modulation of laser light in the heterodyne interferometer setup. The sensitivity of the scanning ACV to different spatial components of the acoustic radiation is analyzed. The animated airborne emission patterns are visualized for the higher harmonic and frequency mixing fields radiated by planar defects. The results confirm a high localization of the nonlinear acoustic emission around the defects and complicated directivity patterns appreciably different from those observed for fundamental frequencies.

  9. Scanning laser polarimetry - a review.

    PubMed

    Da Pozzo, Stefano; Marchesan, Roberta; Ravalico, Giuseppe

    2009-01-01

    Glaucoma is a leading cause of irreversible blindness worldwide. Retinal ganglion cells and their axons represent the selective target of the disease. When visual function is still intact on standard automated perimetry and optic disc appearance is suspicious, an early diagnosis may be supported by the identification of a retinal nerve fibre layer (RNFL) defect in the peripapillary area. At present days, computer-based, real-time imaging of the peripapillary RNFL is available through instruments of easy use and with high levels of accuracy and reproducibility. Scanning laser polarimetry is performed by a confocal scanning laser ophthalmoscope with an integrated polarimeter (GDx-VCC). There is a considerable amount of scientific evidence about the role of this imaging technique for glaucoma diagnosis. The aim of this review is to describe the principles of operation, the examination procedure, the clinical role, the results of main diagnostic studies and the future development of the software for the scanning laser polarimetry.

  10. Digital laser scanning fundus camera.

    PubMed

    Plesch, A; Klingbeil, U; Bille, J

    1987-04-15

    Imaging and documentation of the human retina for clinical diagnostics are conventionally achieved by classical optical methods. We designed a digital laser scanning fundus camera. The optoelectronical instrument is based on scanning laser illumination of the retina and a modified video imaging procedure. It is coupled to a digital image buffer and a microcomputer for image storage and processing. Aside from its high sensitivity the LSF incorporates new ophthalmic imaging methods like polarization differential contrast. We give design considerations as well as a description of the instrument and its performance.

  11. Characterising Vegetation Structural and Functional Differences Across Australian Ecosystems From a Network of Terrestrial Laser Scanning Survey Sites and Airborne and Satellite Image Archives

    NASA Astrophysics Data System (ADS)

    Phinn, S. R.; Armston, J.; Scarth, P.; Johansen, K.; Schaefer, M.; Suarez, L.; Soto-Berelov, M.; Muir, J.; Woodgate, W.; Jones, S.; Held, A. A.

    2015-12-01

    Vegetation structural information is critical for environmental monitoring, management and compliance assessment. In this context we refer to vegetation structural properties as vertical, horizontal and volumetric dimensions, including: canopy height; amount and distribution of vegetation by height; foliage projective cover (FPC); leaf area index (LAI); and above ground biomass. Our aim was to determine if there were significant differences between vegetation structural properties across 11 ecosystem types in Australia as measured by terrestrial laser scanner (TLS) structure metrics. The ecosystems sampled included: mesophyll vineforest, wet-dry tropical savannah, mallee woodland, subtropical eucalypt forest, mulga woodland/grassland, wet eucalypt forest, dry eucalypt forest, tall and wet eucalypt forest, and desert grassland/shrublands. Canopy height, plant area-height profiles and LAI were calculated from consistently processed TLS data using Australia's Terrestrial Ecosystem Research Network's (TERN) Supersites by the TERN AusCover remote sensing field teams from 2012-2015. The Supersites were sampled using standardised field protocols within a core set of 1 ha plots as part of a 5 km x 5 km uniform area using a RIEGL-VZ400 waveform recording TLS. Four to seven scans were completed per plot, with one centre point and then at 25 m away from the centre point along transect lines at 0o, 60o and 240o. Individual foliage profiles were sensitive to spatial variation in the distribution of plant materials. Significant differences were visible between each of the vegetation communities assessed when aggregated to plot and ecosystem type scales. Several of the communities exhibited simple profiles with either grass and shrubs (e.g. desert grassland) or grass and trees (e.g. mallee woodland). Others had multiple vegetation forms at different heights, contributing to the profile (e.g. wet eucalypt forest). The TLS data provide significantly more detail about the relative

  12. Vertically scanned laser sheet microscopy.

    PubMed

    Dong, Di; Arranz, Alicia; Zhu, Shouping; Yang, Yujie; Shi, Liangliang; Wang, Jun; Shen, Chen; Tian, Jie; Ripoll, Jorge

    2014-01-01

    Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

  13. Airborne Tactical Free-Electron Laser

    SciTech Connect

    Whitney, Roy; Neil, George

    2007-02-01

    The goal of 100 kilowatts (kW) of directed energy from an airborne tactical platform has proved challenging due to the size and weight of most of the options that have been considered. However, recent advances in Free-Electron Lasers appear to offer a solution along with significant tactical advantages: a nearly unlimited magazine, time structures for periods from milliseconds to hours, radar like functionality, and the choice of the wavelength of light that best meets mission requirements. For an Airborne Tactical Free-Electron Laser (ATFEL) on a platforms such as a Lockheed C-130J-30 and airships, the two most challenging requirements, weight and size, can be met by generating the light at a higher harmonic, aggressively managing magnet weights, managing cryogenic heat loads using recent SRF R&D results, and using FEL super compact design concepts that greatly reduce the number of components. The initial R&D roadmap for achieving an ATFEL is provided in this paper. Performing this R&D is expected to further reduce the weight, size and power requirements for the FELs the Navy is currently developing for shipboard applications, as well as providing performance enhancements for the strategic airborne MW class FELs. The 100 kW ATFEL with its tactical advantages may prove sufficiently attractive for early advancement in the queue of deployed FELs.

  14. Alternative analysis of airborne laser data collected within conventional multi-parameter airborne geophysical surveys

    NASA Astrophysics Data System (ADS)

    Ahl, Andreas; Supper, R.; Motschka, K.; Schattauer, I.

    2010-05-01

    . These results encouraged us to apply these methods to airborne geophysical data sets from the United Mexican States. One survey was targeted to provide additional data for advanced groundwater modeling in remote areas of the karstic plateau of Yucatan. Within the other project a sustainable source of water supply for a small settlement on the isolated island of Socorro, 700 km off the Mexican main coast had to be detected. At both survey areas no accurate elevation models or area-wide information about vegetation heights where available before the airborne geophysical survey. The results of these investigations will be presented. From an evaluation of the results it can be concluded that the use of laser altimetry not only provides essential information about the ground clearance of the geophysical instruments but also increases the benefit of the airborne survey for the client by delivering additional information about the survey area. It is clear that the accuracy of the resulting data cannot compete with a high resolution laser scanning survey. However in areas where such information is not available an obvious additional benefit can be achieved without the need to spend money for additional survey campaigns. Currently further studies are launched to investigate the possibility to increase the accuracy of the altitude data by determining roll and pitch of the helicopter by the use of differentially corrected multiple L1/L2 band GPS receiver mounted at fixed positions on the helicopter platform. The above study was partly financed by the Austrian Science Fund, Xplore (L524-N10) project.

  15. Estimation of big sagebrush leaf area index with terrestrial laser scanning

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A remote-sensing technique is need to bridge the gap between airborne laser scanning (ALS) and ground-based field techniques for accurately assessing leaf area index (LAI) in sparsely vegetated landscapes like sagebrush steppe. Terrestrial laser scanning (TLS) was used to measure structural variable...

  16. Airborne Laser Mapping of Greenland

    SciTech Connect

    Krabill, W.B.; Thomas, R.H.; Martin, C.F.; Sonntag, J.G.

    1996-10-01

    The Polar ice sheets contain enough water to raise Earth`s sea level by some 70 m. It is not clear whether changes in these ice sheets are contributing to the current rise. Ice sheet mass balance estimates can be obtained by monitoring the topography of selected Polar regions. The Arctic Ice Mapping (AIM) Project is a continuing program designed to provide a record of the absolute height of representative Arctic ice sheets. Using the Global Positioning System (GPS), aircraft flight lines may be duplicated with sufficient tolerance to provide repeated laser elevation measurements from one year to another. The raw GPS measurements are re-processed post-mission to provide sub-10 cm trajectories for each aircraft flight. This program began in 1991 with a proof-of-concept mission to Greenland. The data from this mission demonstrates 20 cm repeatability, principally due to the limited GPS constellation available. Refinements in all phases of the program (software, law and GPS hardware, and a complete GPS constellation) have yielded 10 cm repeatability in data from subsequent years, which includes probable geophysical change in the surface due to storm events and wind drift. 5 refs., 5 figs., 2 tabs.

  17. Linear models for airborne-laser-scanning-based operational forest inventory with small field sample size and highly correlated LiDAR data

    USGS Publications Warehouse

    Junttila, Virpi; Kauranne, Tuomo; Finley, Andrew O.; Bradford, John B.

    2015-01-01

    Modern operational forest inventory often uses remotely sensed data that cover the whole inventory area to produce spatially explicit estimates of forest properties through statistical models. The data obtained by airborne light detection and ranging (LiDAR) correlate well with many forest inventory variables, such as the tree height, the timber volume, and the biomass. To construct an accurate model over thousands of hectares, LiDAR data must be supplemented with several hundred field sample measurements of forest inventory variables. This can be costly and time consuming. Different LiDAR-data-based and spatial-data-based sampling designs can reduce the number of field sample plots needed. However, problems arising from the features of the LiDAR data, such as a large number of predictors compared with the sample size (overfitting) or a strong correlation among predictors (multicollinearity), may decrease the accuracy and precision of the estimates and predictions. To overcome these problems, a Bayesian linear model with the singular value decomposition of predictors, combined with regularization, is proposed. The model performance in predicting different forest inventory variables is verified in ten inventory areas from two continents, where the number of field sample plots is reduced using different sampling designs. The results show that, with an appropriate field plot selection strategy and the proposed linear model, the total relative error of the predicted forest inventory variables is only 5%–15% larger using 50 field sample plots than the error of a linear model estimated with several hundred field sample plots when we sum up the error due to both the model noise variance and the model’s lack of fit.

  18. Line-scanning laser ophthalmoscope

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Ferguson, R. Daniel; Ustun, Teoman E.; Bigelow, Chad E.; Iftimia, Nicusor V.; Webb, Robert H.

    2006-07-01

    Scanning laser ophthalmoscopy (SLO) is a powerful imaging tool with specialized applications limited to research and ophthalmology clinics due in part to instrument size, cost, and complexity. Conversely, low-cost retinal imaging devices have limited capabilities in screening, detection, and diagnosis of diseases. To fill the niche between these two, a hand-held, nonmydriatic line-scanning laser ophthalmoscope (LSLO) is designed, constructed, and tested on normal human subjects. The LSLO has only one moving part and uses a novel optical approach to produce wide-field confocal fundus images. Imaging modes include multiwavelength illumination and live stereoscopic imaging with a split aperture. Image processing and display functions are controlled with two stacked prototype compact printed circuit boards. With near shot-noise limited performance, the digital LSLO camera requires low illumination power (<500 µW) at near-infrared wavelengths. The line-scanning principle of operation is examined in comparison to SLO and other imaging modes. The line-scanning approach produces high-contrast confocal images with nearly the same performance as a flying-spot SLO. The LSLO may significantly enhance SLO utility for routine use by ophthalmologists, optometrists, general practitioners, and also emergency medical personnel and technicians in the field for retinal disease detection and other diverse applications.

  19. Moose (Alces alces) reacts to high summer temperatures by utilizing thermal shelters in boreal forests - an analysis based on airborne laser scanning of the canopy structure at moose locations.

    PubMed

    Melin, Markus; Matala, Juho; Mehtätalo, Lauri; Tiilikainen, Raisa; Tikkanen, Olli-Pekka; Maltamo, Matti; Pusenius, Jyrki; Packalen, Petteri

    2014-04-01

    The adaptation of different species to warming temperatures has been increasingly studied. Moose (Alces alces) is the largest of the ungulate species occupying the northern latitudes across the globe, and in Finland it is the most important game species. It is very well adapted to severe cold temperatures, but has a relatively low tolerance to warm temperatures. Previous studies have documented changes in habitat use by moose due to high temperatures. In many of these studies, the used areas have been classified according to how much thermal cover they were assumed to offer based on satellite/aerial imagery data. Here, we identified the vegetation structure in the areas used by moose under different thermal conditions. For this purpose, we used airborne laser scanning (ALS) data extracted from the locations of GPS-collared moose. This provided us with detailed information about the relationships between moose and the structure of forests it uses in different thermal conditions and we were therefore able to determine and differentiate between the canopy structures at locations occupied by moose during different thermal conditions. We also discovered a threshold beyond which moose behaviour began to change significantly: as day temperatures began to reach 20 °C and higher, the search for areas with higher and denser canopies during daytime became evident. The difference was clear when compared to habitat use at lower temperatures, and was so strong that it provides supporting evidence to previous studies, suggesting that moose are able to modify their behaviour to cope with high temperatures, but also that the species is likely to be affected by warming climate.

  20. Differential Multiphoton Laser Scanning Microscopy

    SciTech Connect

    Field, Jeffrey J.; Sheetz, Kraig E.; Chandler, Eric V.; Hoover, Erich E.; Young, Michael D.; Ding, Shi-you; Sylvester, Anne W.; Kleinfeld, David; Squier, Jeff A.

    2012-01-01

    Multifocal multiphoton laser scanning microscopy (mfMPLSM) in the biological and medical sciences has the potential to become a ubiquitous tool for obtaining high-resolution images at video rates. While current implementations of mfMPLSM achieve very high frame rates, they are limited in their applicability to essentially those biological samples that exhibit little or no scattering. In this paper, we report on a method for mfMPLSM in which whole-field detection with a single detector, rather than detection with a matrix of detectors, such as a charge-coupled device (CCD) camera, is implemented. This advance makes mfMPLSM fully compatible for use in imaging through scattering media. Further, we demonstrate that this method makes it possible to simultaneously obtain multiple images and view differences in excitation parameters in a single scan of the specimen.

  1. Integrated approach to airborne laser communication

    NASA Astrophysics Data System (ADS)

    Louthain, James A.

    Lasers offer tremendous advantages over RF communication systems in terms of bandwidth and security due to their ultra-high frequency and narrow spatial beamwidth. Unfortunately, atmospheric turbulence significantly increases the received power variation and bit error rate (BER) in free-space optical communication (FSOC) systems. Further, airborne optical communication systems require special considerations in size, complexity, power, and weight. If two or more laser beams are sufficiently separated so that their turbulence effects are uncorrelated (i.e. anisoplanatic), they can effectively "average out" turbulence effects. This requisite separation distance is derived for multiple geometries, turbulence conditions, and optical properties. In most cases and geometries, the angles ordered from largest to smallest are: phase uncorrelated angle (equivalent to the tilt uncorrelated angle and phase anisoplanatic angle), tilt isoplanatic angle, phase isoplanatic angle, scintillation uncorrelated angle (or scintillation anisoplanatic angle), and scintillation isoplanatic angle ( qyind > thetaTA > theta0 > qcind > qc0 ). Conventional adaptive optics (AO) systems only correct for phase and cannot correct for strong scintillation, while multiple-transmitter systems use several transmission paths to "average out" effects of the strong scintillation by incoherently summing up the beams in the receiver. Since all three airborne geometries (air-to-air, air-to-ground, and ground-to-air) are studied, a comparison of multiple-beam airborne laser communication system performance is presented for the first time. Wave optics simulations show that a combination of transmitter diversity, receiver and transmitter trackers, and adaptive thresholding can significantly reduce BER in an air-to-air FSOC system by over 10,000 times. As demonstrated in this work, two transmitters alone separated by only 31 cm (100 km path length, 1.55 mum wavelength, 4 km in altitude) provide a significant BER

  2. Integrated approach to airborne laser communication

    NASA Astrophysics Data System (ADS)

    Louthain, James A.; Schmidt, Jason D.

    2008-10-01

    Lasers offer tremendous advantages over RF communication systems in bandwidth and security, due to their ultrahigh frequency and narrow spatial beamwidth. Unfortunately, atmospheric turbulence causes severe received power variations and significant bit error rates (BERs) in free-space optical communication (FSOC). Airborne optical communication systems require special considerations in size, complexity, power, and weight. We alleviate the deleterious effects of turbulence by integrating multiple techniques into an on/off keying direct detection system. Wave optics simulations show a combination of transmitter diversity, receiver and transmitter trackers, and adaptive thresholding significantly reduces the BER in air-to-air FSOC (up to 13 dB). Two transmitters alone provide a significant BER improvement over one transmitter, especially for the strong turbulence regime with up to a 9 dB improvement. Two beams also provide a reduction in fade length, indicating they will probably provide even greater improvement with interleaving and forward error correction coding.

  3. Design and Development of a Scanning Airborne Direct Detection Doppler Lidar System

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce; McGill, Matthew; Schwemmer, Geary; Hardesty, Michael; Brewer, Alan; Wilkerson, Thomas; Atlas, Robert; Sirota, Marcos; Lindemann, Scott

    2006-01-01

    In the fall of 2005 we began developing an airborne scanning direct detection molecular Doppler lidar. The instrument is being built as part of the Tropospheric Wind Lidar Technology Experiment (TWiLiTE), a three year project selected by the NASA Earth Sun Technology Office under the Instrument Incubator Program. The TWiLiTE project is a collaboration involving scientists and engineers from NASA Goddard Space Flight Center, NOAA ESRL, Utah State University Space Dynamics Lab, Michigan Aerospace Corporation and Sigma Space Corporation. The TWiLiTE instrument will leverage significant research and development investments made by NASA Goddard and it's partners in the past several years in key lidar technologies and sub-systems (lasers, telescopes, scanning systems, detectors and receivers) required to enable spaceborne global wind lidar measurement. These sub-systems will be integrated into a complete molecular direct detection Doppler wind lidar system designed for autonomous operation on a high altitude aircraft, such as the NASA WB57. The WB57 flies at an altitude of 18 km and from this vantage point the nadir viewing Doppler lidar will be able to profile winds through the full troposphere. The TWiLiTE integrated airborne Doppler lidar instrument will be the first demonstration of a airborne scanning direct detection Doppler lidar and will serve as a critical milestone on the path to a future spaceborne tropospheric wind system. In addition to being a technology testbed for space based tropospheric wind lidar, when completed the TWiLiTE high altitude airborne lidar will be used for studying mesoscale dynamics and storm research (e.g. winter storms, hurricanes) and could be used for calibration and validation of satellite based wind systems such as ESA's Aeolus Atmospheric Dynamics Mission. The TWiLiTE Doppler lidar will have the capability to profile winds in clear air from the aircraft altitude of 18 km to the surface with 250 m vertical resolution and < 2mls

  4. Geodetic Laser Scanning: Refractive Optics Offer Wide Variety of Scan Patterns

    NASA Astrophysics Data System (ADS)

    Carter, W. E.; Shrestha, R. L.; Slatton, C. K.; Shrestha, K. Y.; Cossio, T.

    2005-12-01

    Most commercial geodetic laser mapping instruments use reflective element scanners, often a single nutating or oscillating mirror, and sometimes dual axis units, to create a specific pattern of laser spots on the surface being mapped. The user may be able to set the scanning speed (scan lines per second) and field of coverage (range of scan angles), but the basic pattern of points sampled is fixed. Engineers developing scanners for a surprisingly diverse set of applications, ranging from bar code scanning, to compensating for image motion in astronomical telescopes, to scanning spectrometers, have increasingly turned to refractive scanners-most particularly to scanners that utilize "Risley prisms." Samuel Doty Risley (1845-1920), an ophthalmologist, invented an optometer that contained a pair of thin prisms that rotated in opposite directions about their optical axes to change the convergence of light rays from a single source. He used his optometer measure the visual acuity of patients eyes, as a function of distance. In this original application, both prisms were driven by a common gear assembly, which resulted in a nearly linear scan line. But if the prisms are driven independently in both direction and angular speed, a wide variety of scan patterns can be generated. The University of Florida is developing, a photon counting geodetic laser scanning instrument that will use a Risley prism scanner. The scanner, being built by Sigma Space Inc., will be capable of producing nearly linear scan lines (saw tooth pattern from moving platform), circular scans lines (helical pattern from a moving platform) and any number of rosette scan patterns that are particularly interesting for fixed ground based work. The flexibility provided by the scanner offers the possibility of using the same sensor for airborne and ground based geodetic laser scanning. Examples of the scanner patterns and the initial results from laboratory and early field tests will be presented.

  5. Dual-Frequency Airborne Scanning Rain Radar Antenna System

    NASA Technical Reports Server (NTRS)

    Hussein, Ziad A.; Green, Ken

    2004-01-01

    A compact, dual-frequency, dual-polarization, wide-angle-scanning antenna system has been developed as part of an airborne instrument for measuring rainfall. This system is an upgraded version of a prior single-frequency airborne rain radar antenna system and was designed to satisfy stringent requirements. One particularly stringent combination of requirements is to generate two dual-polarization (horizontal and vertical polarizations) beams at both frequencies (13.405 and 35.605 GHz) in such a way that the beams radiated from the antenna point in the same direction, have 3-dB angular widths that match within 25 percent, and have low sidelobe levels over a wide scan angle at each polarization-and-frequency combination. In addition, the system is required to exhibit low voltage standing-wave ratios at both frequencies. The system (see figure) includes a flat elliptical scanning reflector and a stationary offset paraboloidal reflector illuminated by a common-aperture feed system that comprises a corrugated horn with four input ports one port for each of the four frequency-and-polarization combinations. The feed horn is designed to simultaneously (1) under-illuminate the reflectors 35.605 GHz and (2) illuminate the reflectors with a 15-dB edge taper at 13.405 GHz. The scanning mirror is rotated in azimuth to scan the antenna beam over an angular range of 20 in the cross-track direction for wide swath coverage, and in elevation to compensate for the motion of the aircraft. The design of common-aperture feed horn makes it possible to obtain the required absolute gain and low side-lobe levels in wide-angle beam scanning. The combination of the common-aperture feed horn with the small (0.3) focal-length-to-diameter ratio of the paraboloidal reflector makes it possible for the overall system to be compact enough that it can be mounted on a DC-8 airplane.

  6. Scanning laser polarimetry in glaucoma.

    PubMed

    Dada, Tanuj; Sharma, Reetika; Angmo, Dewang; Sinha, Gautam; Bhartiya, Shibal; Mishra, Sanjay K; Panda, Anita; Sihota, Ramanjit

    2014-11-01

    Glaucoma is an acquired progressive optic neuropathy which is characterized by changes in the optic nerve head and retinal nerve fiber layer (RNFL). White-on-white perimetry is the gold standard for the diagnosis of glaucoma. However, it can detect defects in the visual field only after the loss of as many as 40% of the ganglion cells. Hence, the measurement of RNFL thickness has come up. Optical coherence tomography and scanning laser polarimetry (SLP) are the techniques that utilize the evaluation of RNFL for the evaluation of glaucoma. SLP provides RNFL thickness measurements based upon the birefringence of the retinal ganglion cell axons. We have reviewed the published literature on the use of SLP in glaucoma. This review elucidates the technological principles, recent developments and the role of SLP in the diagnosis and monitoring of glaucomatous optic neuropathy, in the light of scientific evidence so far.

  7. Absolute tracer dye concentration using airborne laser-induced water Raman backscatter

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1981-01-01

    The use of simultaneous airborne-laser-induced dye fluorescence and water Raman backscatter to measure the absolute concentration of an ocean-dispersed tracer dye is discussed. Theoretical considerations of the calculation of dye concentration by the numerical comparison of airborne laser-induced fluorescence spectra with laboratory spectra for known dye concentrations using the 3400/cm OH-stretch water Raman scatter as a calibration signal are presented which show that minimum errors are obtained and no data concerning water mass transmission properties are required when the laser wavelength is chosen to yield a Raman signal near the dye emission band. Results of field experiments conducted with an airborne conical scan lidar over a site in New York Bight into which rhodamine dye had been injected in a study of oil spill dispersion are then indicated which resulted in a contour map of dye concentrations, with a minimum detectable dye concentration of approximately 2 ppb by weight.

  8. Helicopter Airborne Laser Positioning System (HALPS)

    NASA Technical Reports Server (NTRS)

    Eppel, Joseph C.; Christiansen, Howard; Cross, Jeffrey; Totah, Joseph

    1990-01-01

    The theory of operation, configuration, laboratory, and ground test results obtained with a helicopter airborne laser positioning system developed by Princeton University is presented. Unfortunately, due to time constraints, flight data could not be completed for presentation at this time. The system measures the relative position between two aircraft in three dimensions using two orthogonal fan-shaped laser beams sweeping across an array of four detectors. Specifically, the system calculates the relative range, elevation, and azimuth between an observation aircraft and a test helicopter with a high degree of accuracy. The detector array provides a wide field of view in the presence of solar interference due to compound parabolic concentrators and spectral filtering of the detector pulses. The detected pulses and their associated time delays are processed by the electronics and are sent as position errors to the helicopter pilot who repositions the aircraft as part of the closed loop system. Accuracies obtained in the laboratory at a range of 80 ft in the absence of sunlight were + or - 1 deg in elevation; +0.5 to -1.5 deg in azimuth; +0.5 to -1.0 ft in range; while elevation varied from 0 to +28 deg and the azimuth varied from 0 to + or - 45 deg. Accuracies in sunlight were approximately 40 deg (+ or - 20 deg) in direct sunlight.

  9. Wedge-Filtering of Geomorphologic Terrestrial Laser Scan Data

    PubMed Central

    Panholzer, Helmut; Prokop, Alexander

    2013-01-01

    Terrestrial laser scanning is of increasing importance for surveying and hazard assessments. Digital terrain models are generated using the resultant data to analyze surface processes. In order to determine the terrain surface as precisely as possible, it is often necessary to filter out points that do not represent the terrain surface. Examples are vegetation, vehicles, and animals. Filtering in mountainous terrain is more difficult than in other topography types. Here, existing automatic filtering solutions are not acceptable, because they are usually designed for airborne scan data. The present article describes a method specifically suitable for filtering terrestrial laser scanning data. This method is based on the direct line of sight between the scanner and the measured point and the assumption that no other surface point can be located in the area above this connection line. This assumption is only true for terrestrial laser data, but not for airborne data. We present a comparison of the wedge filtering to a modified inverse distance filtering method (IDWMO) filtered point cloud data. Both methods use manually filtered surfaces as reference. The comparison shows that the mean error and root–mean-square-error (RSME) between the results and the manually filtered surface of the two methods are similar. A significantly higher number of points of the terrain surface could be preserved, however, using the wedge-filtering approach. Therefore, we suggest that wedge-filtering should be integrated as a further parameter into already existing filtering processes, but is not suited as a standalone solution so far. PMID:23429548

  10. Airborne laser mapping of Assateague National Seashore Beach

    USGS Publications Warehouse

    Krabill, W.B.; Wright, C.W.; Swift, R.N.; Frederick, E.B.; Manizade, S.S.; Yungel, J.K.; Martin, C.F.; Sonntag, J.G.; Duffy, Mark; Hulslander, William; Brock, John C.

    2000-01-01

    Results are presented from topographic surveys of the Assateague Island National Seashore using an airborne scanning laser altimeter and kinematic Global Positioning System (GPS) technology. The instrument used was the Airborne Topographic Mapper (ATM), developed by the NASA Arctic Ice Mapping (AIM) group from the Goddard Space Flight Center's Wallops Flight Facility. In November, 1995, and again in May, 1996, these topographic surveys were flown as a functionality check prior to conducting missions to measure the elevation of extensive sections of the Greenland Ice Sheet as part of NASA's Global Climate Change program. Differences between overlapping portions of both surveys are compared for quality control. An independent assessment of the accuracy of the ATM survey is provided by comparison to surface surveys which were conducted using standard techniques. The goal of these projects is to make these measurements to an accuracy of ± 10 cm. Differences between the fall 1995 and 1996 surveys provides an assessment of net changes in the beach morphology over an annual cycle.

  11. Turbulence control on an airborne laser platform

    NASA Technical Reports Server (NTRS)

    Gad-El-hak, Mohamed

    1987-01-01

    An active flow control device to generate large-scale, periodic structures in a turbulent shear flow is developed. Together with adaptive optics, the device may be used on airborne laser platforms to reduce or eliminate optical distortion caused by the turbulence in the aircraft's boundary layer. A cyclic jet issuing from a spanwise slot is used to collect the turbulent boundary layer for a finite time and then release all of the flow instantaneously in one large eddy that convects downstream. Flow visualization and hot-film probe measurements are used together with pattern recognition algorithms to demonstrate the viability of the flow control method. A flat plate towed in a water channel is used as a test bed. The instantaneous velocity signal is used to compute important statistical quantities of the random velocity field, such as the mean, the root-mean-square, the spectral distribution, and the probability density function. When optimized for a given boundary layer, it is shown that the cyclic jet will produce periodic structures that are similar to the random, naturally occurring ones. These structures seem to trigger the onset of bursting events near the wall of the plate. Thus, the present device generates periodic structures in both the outer and inner regions of a turbulent boundary layer.

  12. Validation of Airborne CO2 Laser Measurements

    NASA Astrophysics Data System (ADS)

    Browell, E. V.; Dobler, J. T.; Kooi, S.; Fenn, M. A.; Choi, Y.; Vay, S. A.; Harrison, F. W.; Moore, B.; Zaccheo, T. S.

    2010-12-01

    This paper discusses the flight test validation of a unique, multi-frequency, intensity-modulated, single-beam laser absorption spectrometer (LAS) that operates near 1.57 μm for remote column CO2 measurements. This laser system is under development for a future space-based mission to determine the global distribution of regional-scale CO2 sources and sinks, which is the objective of the NASA Active Sensing of CO2 Emissions during Nights, Days, and Seasons (ASCENDS) mission. A prototype of this LAS system, called the Multi-frequency Fiber Laser Lidar (MFLL), was developed by ITT, and it has been flight tested in nine airborne campaigns since May 2005. This paper focuses on the most recent results obtained over the last two years of flight-testing where the MFLL remote CO2 column measurements were evaluated against airborne in situ CO2 profile measurements traceable to World Meteorological Organization standards. A comprehensive multiple-aircraft flight test program was conducted over Oklahoma and Virginia in July-August 2009. The MFLL obtained surface reflectance and average CO2 column variations along the 50-km flight legs over the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Central Facility (CF) in Lamont, Oklahoma; over rural Virginia and North Carolina; and over the Chesapeake Bay. For a flight altitude of 4.6 km, the average signal to noise ratio (SNR) for a 1-s CO2 column measurement was found to be 760, which is the equivalent of a CO2 mixing ratio precision of 0.60 ppmv, and for a 10-s average the SNR was found to be 2002 or 0.20 ppmv. Absolute comparisons of MFLL-derived and in situ-derived CO2 column measurements were made for all daytime flights conducted over Oklahoma and Virginia with an average agreement to within 0.32 ppmv. A major ASCENDS flight test campaign was conducted using the NASA DC-8 during 6-18 July 2010. The MFLL system and associated in situ CO2 instrumentation were operated on DC-8 flights over the Central Valley

  13. Photon Counting Airborne Laser Swath Mapping

    NASA Astrophysics Data System (ADS)

    Carter, W. E.; Shrestha, R. L.; Slatton, K. C.

    2004-05-01

    During the past decade airborne laser swath mapping (ALSM) has brought topographic mapping to the forefront of geodesy. ALSM has made it possible, for the first time, to study natural geo-surficial processes on spatial scales extending from meters to hundreds of kilometers, all in a consistent geodetic frame of reference. The conventional approach to ALSM has been to use lasers with enough energy per pulse, and optics with large enough collecting areas, to obtain returns of thousands of photons per shot. This approach minimizes the impact of spurious range values caused by noise, such as background solar radiation and sensor thermal noise, but also constrains the minimum size, weight and power consumption of the hardware. Current systems typically operate at rates approaching 100,000 pulses per second, and another order of magnitude increase would be needed to provide contiguous coverage with a spatial resolution of 30 cm or better. This high signal-to-noise ratio approach affords little scalability for significantly downsizing the hardware, or reducing the costs. University of Florida (UF) researchers are developing an ALSM unit based on a different paradigm, which we refer to as photon counting ALSM, or simply PC-ALSM. The approach is to transmit relatively low energy laser pulses, and to illuminate a surface `patch' about an order of magnitude larger than the typical footprint of a conventional ALSM system. The returning signal will have far fewer photons per unit area of the receive optics, making it more difficult to discriminate between return signal and noise. If a single channel detector were used, the spatial resolution would also be degraded. However, by using a multi-channel photomultiplier tube to detect the returns, the surface patch can be divided into an array of groundals, and by using a multi-stop timing system false ranges can be filtered out of the data during post flight processing. Researchers at NASA GSFC have already tested a first generation

  14. Airborne bathymetric charting using pulsed blue-green lasers.

    PubMed

    Kim, H H

    1977-01-01

    Laboratory and airborne experiments have proven the feasibility and demonstrated the techniques of an airborne pulsed laser system for rapidly mapping coastal water bathymetry. Water depths of 10 +/- 0.25 m were recorded in waters having an effective attenuation coefficient of 0.175 m(-1). A2-MW peak power Nd:YAG pulsed laser was flown at an altitude of 600 m. An advanced system, incorporating a mirror scanner, a high pulsed rate laser, and a good signal processor, could survey coastal zones at the rate of several square miles per hour.

  15. Airborne bathymetric charting using pulsed blue-green lasers

    NASA Technical Reports Server (NTRS)

    Kim, H. H.

    1977-01-01

    Laboratory and airborne experiments have proven the feasibility and demonstrated the techniques of an airborne pulsed laser system for rapidly mapping coastal water bathymetry. Water depths of 10 plus or minus 0.25 m were recorded in waters having an effective attenuation coefficient of 0.175 m. A 2-MW peak power Nd:YAG pulsed laser was flown at an altitude of 600 m. An advanced system, incorporating a mirror scanner, a high pulsed rate laser, and a good signal processor, could survey coastal zones at the rate of several square miles per hour.

  16. AIRBORNE INERTIAL SURVEYING USING LASER TRACKING AND PROFILING TECHNIQUES.

    USGS Publications Warehouse

    Cyran, Edward J.; ,

    1986-01-01

    The U. S. Geological Survey through a contract with the Charles Stark Draper Laboratory has developed the Aerial Profiling of Terrain System. This is an airborne inertial surveying system designed to use a laser tracker to provide position and velocity updates, and a laser profiler to measure terrain elevations. The performance characteristics of the system are discussed with emphasis placed on the performance of the laser devices. The results of testing the system are summarized for both performance evaluation and applications.

  17. Tunable Infrared Laser Instruments for Airborne Atmospheric Studies

    NASA Technical Reports Server (NTRS)

    Fried, A.; Diskin, G.; Weibring, P.; Richter, D.; Walega, J. G.; Sachse, G.; Slate, T.; Rana, M.; Podolske, J.

    2008-01-01

    Tunable infrared laser-based instruments on airborne platforms have provided invaluable contributions to atmospheric studies over the past several decades. This paper presents an overview of some recent studies and developments using this approach that were presented at the 2007 Field Laser Applications in Industry and Research (FLAIR, http://www.inoa.it/flair/) conference in Florence, Italy. The present overview only covers select in situ absorption-based instruments that were presented in the airborne session at this conference. In no case are comprehensive details presented. These details can be found in the numerous references given. Additional approaches based upon cavity-enhanced and photoacoustic measurements, which are also making invaluable contributions in airborne atmospheric studies, are not discussed in this brief overview.

  18. Categorisation of full waveform data provided by laser scanning devices

    NASA Astrophysics Data System (ADS)

    Ullrich, Andreas; Pfennigbauer, Martin

    2011-11-01

    In 2004, a laser scanner device for commercial airborne laser scanning applications, the RIEGL LMS-Q560, was introduced to the market, making use of a radical alternative approach to the traditional analogue signal detection and processing schemes found in LIDAR instruments so far: digitizing the echo signals received by the instrument for every laser pulse and analysing these echo signals off-line in a so-called full waveform analysis in order to retrieve almost all information contained in the echo signal using transparent algorithms adaptable to specific applications. In the field of laser scanning the somewhat unspecific term "full waveform data" has since been established. We attempt a categorisation of the different types of the full waveform data found in the market. We discuss the challenges in echo digitization and waveform analysis from an instrument designer's point of view and we will address the benefits to be gained by using this technique, especially with respect to the so-called multi-target capability of pulsed time-of-flight LIDAR instruments.

  19. Hurricane Wind Field Measurements with Scanning Airborne Doppler Lidar During CAMEX-3

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Cutten, D. R.; Howell, J. N.; Darby, L. S.; Hardesty, R. M.; Traff, D. M.; Menzies, R. T.

    2000-01-01

    During the 1998 Convection and Moisture Experiment (CAMEX-3), the first hurricane wind field measurements with Doppler lidar were achieved. Wind fields were mapped within the eye, along the eyewall, in the central dense overcast, and in the marine boundary layer encompassing the inflow region. Spatial coverage was determined primarily by cloud distribution and opacity. Within optically-thin cirrus slant range of 20- 25 km was achieved, whereas no propagation was obtained during penetration of dense cloud. Measurements were obtained with the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) on the NASA DC-8 research aircraft. MACAWS was developed and operated cooperatively by the atmospheric lidar remote sensing groups of NOAA Environmental Technology Laboratory, NASA Marshall Space Flight Center, and Jet Propulsion Laboratory. A pseudo-dual Doppler technique ("co-planar scanning") is used to map the horizontal component of the wind at several vertical levels. Pulses from the laser are directed out the left side of the aircraft in the desired directions using computer-controlled rotating prisms. Upon exiting the aircraft, the beam is completely eyesafe. Aircraft attitude and speed are taken into account during real-time signal processing, resulting in determination of the ground-relative wind to an accuracy of about 1 m/s magnitude and about 10 deg direction. Beam pointing angle errors are about 0.1 deg, equivalent to about 17 m at 10 km. Horizontal resolution is about 1 km (along-track) for typical signal processor and scanner settings; vertical resolution varies with range. Results from CAMEX-3 suggest that scanning Doppler wind lidar can complement airborne Doppler radar by providing wind field measurements in regions that are devoid of hydrometeors. At present MACAWS observations are being assimilated into experimental forecast models and satellite Doppler wind lidar simulations to evaluate the relative impact.

  20. The design of laser scanning galvanometer system

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoling; Zhou, Bin; Xie, Weihao; Zhang, Yuangeng

    2015-02-01

    In this paper, we designed the laser scanning galvanometer system according to our requirements. Based on scanning range of our laser scanning galvanometer system, the design parameters of this system were optimized. During this work, we focused on the design of the f-θ field lens. An optical system of patent lens in the optical manual book, which had three glasses structure, was used in our designs. Combining the aberration theory, the aberration corrections and image quality evaluations were finished using Code V optical design software. An optimum f-θ field lens was designed, which had focal length of 434 mm, pupil diameter of 30 mm, scanning range of 160 mm × 160 mm, and half field angle of 18°×18°. At the last, we studied the influences of temperature changes on our system.

  1. The relaxed confocal scanning laser ophthalmoscope.

    PubMed

    Van de Velde, F J

    2006-01-01

    The development of the Scanning Laser Ophthalmoscope is reviewed from a historical perspective. Since a flying-spot scanning principle for an electro-optical ophthalmoscope was first disclosed in 1950, enabling milestones have included the introduction of the laser and inversion of the usual Gullstrand's configuration of optical pupils in 1977, and the application of the optical principle of confocality by means of double or de-scanning in 1983. As a result, high resolution and high contrast confocal infra-red ophthalmoscopy with a 790 nm diode laser, at video rates, is a major novel imaging modality when compared to traditional optical techniques. This imaging mode is ideal to provide the necessary fiducial landmarks for microperimetry, therapeutic laser and SD-OCT based optical sectioning of the retina. DPSS or He-Ne lasers emitting at 532, 543, 561 or 575 nm are used for complimentary red-free fundus imaging. The diode 790 nm and DPSS 490 nm lasers are also used for fluorescence excitation.

  2. Airborne Laser (ABL): Issues for Congress

    DTIC Science & Technology

    2007-07-09

    bulbous turret on the front of the aircraft, but the COIL (Chemical Oxygen Iodine laser) is located in the aft section of the aircraft. System Overview...Chemical Oxygen Iodine Laser). COIL generates its energy through an onboard chemical reaction of oxygen and iodine molecules. Because this laser...The Air Force, and other Services, frequently complain about the onerous and disproportionate O&S (Operations and Support) costs of “high demand, low

  3. Defect Detection Using a Scanning Laser Source

    NASA Astrophysics Data System (ADS)

    Burrows, S. E.; Dixon, S.

    2011-06-01

    Surface breaking defects are identified using a scanning laser source. A Q-switched Nd-YAG laser is used as a non-contact source of ultrasound and an electromagnetic acoustic transducer (EMAT) employed as detector. For a thin plate, an increase in frequency content of the received wave is observed when the laser spot is situated directly over the defect. Time-frequency analysis using a Wigner transform has enabled individual Lamb wave modes to be identified, while propagation of Lamb waves through aluminium sheet is studied by finite element analysis.

  4. A Portable Airborne Scanning Lidar System for Ocean and Coastal Applications

    DTIC Science & Technology

    2009-06-26

    has been quantified in many studies with several different airborne lidar systems. Robertson et al. (2007) measured beach erosion caused by Hurricane...Mech., 156, 505–531. Robertson , W., K. Zhang, and D. Whitman, 2007: Hurricane- induced beach change derived from airborne laser mea- surements near...level changes on Southern California beaches. Ph.D. thesis, University of California, San Diego, 155 pp. ——, R. Guza, R. Gutierrez, and R. Seymour

  5. Land-Based Mobile Laser Scanning Systems: a Review

    NASA Astrophysics Data System (ADS)

    Puente, I.; González-Jorge, H.; Arias, P.; Armesto, J.

    2011-09-01

    Mobile mapping has been using various photogrammetric techniques for many years. In recent years, there has been an increase in the number of mobile mapping systems using laser scanners available in the market, partially because of the improvement in GNSS/INS performance for direct georeferencing. In this article, some of the most important land-based mobile laser scanning (MLS) systems are reviewed. Firstly, the main characteristics of MLS systems vs. airborne (ALS) and terrestrial laser scanning (TLS) systems are compared. Secondly, a short overview of the mobile mapping technology is also provided so that the reader can fully grasp the complexity and operation of these devices. As we put forward in this paper, a comparison of different systems is briefly carried out regarding specifications provided by the manufacturers. Focuses on the current research are also addressed with emphasis on the practical applications of these systems. Most of them have been utilized for data collection on road infrastructures or building façades. This article shows that MLS technology is nowadays well established and proven, since the demand has grown to the point that there are several systems suppliers offering their products to satisfy this particular market.

  6. Airborne Measurements of Atmospheric Methane Using Pulsed Laser Transmitters

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Riris, Haris; Wu, Stewart; Gonzalez, Brayler; Rodriguez, Michael; Hasselbrack, William; Fahey, Molly; Yu, Anthony; Stephen, Mark; Mao, Jianping; Kawa, Stephan

    2016-01-01

    Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. At NASA Goddard Space Flight Center (GSFC) we have been developing a laser-based technology needed to remotely measure CH4 from orbit. We report on our development effort for the methane lidar, especially on our laser transmitters and recent airborne demonstration. Our lidar transmitter is based on an optical parametric process to generate near infrared laser radiation at 1651 nanometers, coincident with a CH4 absorption. In an airborne flight campaign in the fall of 2015, we tested two kinds of laser transmitters --- an optical parametric amplifier (OPA) and an optical parametric oscillator (OPO). The output wavelength of the lasers was rapidly tuned over the CH4 absorption by tuning the seed laser to sample the CH4 absorption line at several wavelengths. This approach uses the same Integrated Path Differential Absorption (IPDA) technique we have used for our CO2 lidar for ASCENDS. The two laser transmitters were successfully operated in the NASAs DC-8 aircraft, measuring methane from 3 to 13 kilometers with high precision.

  7. Monitoring stream bluff erosion using repeat terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Neitzel, G.; Gran, K. B.

    2012-12-01

    Terrestrial laser scanning (TLS) technology provides high-resolution topographic data that can be used to detect geomorphic change in fluvial environments. In this study, we utilize successive terrestrial laser scans to investigate the relationship between peak flow rates and stream bluff erosion in the Amity Creek watershed in Duluth, Minnesota. We also combine TLS scan results with bluff inventories from airborne lidar to estimate the volume of sediment erosion from bluffs in the watershed, which is an important source of fine sediment contributing to the creek's turbidity impairment. We selected nine study bluffs to conduct terrestrial laser scans on after all significant flood events over a two-year time period. The study employs a Faro Focus 3D phase-shift laser to collect data. Post-processing of the TLS-point cloud data sets involves: (1) removal of vegetation and objects other than the erosional surface of interest; (2) decimation of the point cloud in PC Tools and extraction of zmin values to produce a data set manageable in GIS; (3) creation of a bare earth digital elevation model (DEM) for each set of scans using ArcMap; and (4) utilization of Geomorphic Change Detection (GCD) software to generate DEMs of Difference (DODs) from subsequent terrestrial laser scans. Preliminary results from three flooding events indicate significant erosional activity at all field sites. Slumps were observed at two bluffs following spring melt and freeze/thaw cycling. Two major precipitation events in late spring and early summer provided a unique opportunity to observe the impact of extreme high flow events on bluff erosion throughout the watershed using TLS technology. 4.75 inches of intermittent rain over a six-day period in late May 2012 (May 23-28) resulted in slumping at many bluffs and one major failure. The ≥100-year flood that occurred on June 19-20 (7.25 inches), 2012 was powerful enough to induce considerable channel change. Slumps occurred at six study sites

  8. Voxel Based Representation of Full-Waveform Airborne Laser Scanner Data for Forestry Applications

    NASA Astrophysics Data System (ADS)

    Stelling, N.; Richter, K.

    2016-06-01

    The advantages of using airborne full-waveform laser scanner data in forest applications, e.g. for the description of the vertical vegetation structure or accurate biomass estimation, have been emphasized in many publications. To exploit the full potential offered by airborne full-waveform laser scanning data, the development of voxel based methods for data analysis is essential. In contrast to existing approaches based on the extraction of discrete 3D points by a Gaussian decomposition, it is very promising to derive the voxel attributes from the digitised waveform directly. For this purpose, the waveform data have to be transferred into a 3D voxel representation. This requires a series of radiometric and geometric transformations of the raw full-waveform laser scanner data. Thus, the paper deals with the geometric aspects and describes a processing chain from the raw waveform data to an attenuationcorrected volumetric forest stand reconstruction. The integration of attenuation-corrected waveform data into the voxel space is realised with an efficient parametric voxel traversal method operating on an octree data structure. The voxel attributes are derived from the amplitudes of the attenuation-corrected waveforms. Additionally, a new 3D filtering approach is presented to eliminate non-object voxel. Applying these methods to real full-waveform laser scanning data, a voxel based representation of a spruce was generated combining three flight strips from different viewing directions.

  9. Covariance analysis of the airborne laser ranging system

    NASA Technical Reports Server (NTRS)

    Englar, T. S., Jr.; Hammond, C. L.; Gibbs, B. P.

    1981-01-01

    The requirements and limitations of employing an airborne laser ranging system for detecting crustal shifts of the Earth within centimeters over a region of approximately 200 by 400 km are presented. The system consists of an aircraft which flies over a grid of ground deployed retroreflectors, making six passes over the grid at two different altitudes. The retroreflector baseline errors are assumed to result from measurement noise, a priori errors on the aircraft and retroreflector positions, tropospheric refraction, and sensor biases.

  10. Airborne Visible Laser Optical Communications (AVLOC) experiment

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A series of optical communication experiments between a high altitude aircraft at 18.3 km (60,000 ft) and a ground station were conducted by NASA from summer 1972 through winter 1973. The basic system was an optical tracker and transmitter located in each terminal. The aircraft transceiver consisted of a 5-mW HeNe laser transmitter with a 30-megabit modulator. The ground station beacon was an argon laser operating at 488 nm. A separate pulsed laser radar was used for initial acquisition. The objective of the experiment was to obtain engineering data on the precision tracking and communication system performance at both terminals. Atmospheric effects on the system performance was also an experiment objective. The system description, engineering analysis, testing, and flight results are discussed.

  11. NASA three-laser airborne differential absorption lidar system electronics

    NASA Technical Reports Server (NTRS)

    Allen, R. J.; Copeland, G. D.

    1984-01-01

    The system control and signal conditioning electronics of the NASA three laser airborne differential absorption lidar (DIAL) system are described. The multipurpose DIAL system was developed for the remote measurement of gas and aerosol profiles in the troposphere and lower stratosphere. A brief description and photographs of the majority of electronics units developed under this contract are presented. The precision control system; which includes a master control unit, three combined NASA laser control interface/quantel control units, and three noise pulse discriminator/pockels cell pulser units; is described in detail. The need and design considerations for precision timing and control are discussed. Calibration procedures are included.

  12. Lens based adaptive optics scanning laser ophthalmoscope.

    PubMed

    Felberer, Franz; Kroisamer, Julia-Sophie; Hitzenberger, Christoph K; Pircher, Michael

    2012-07-30

    We present an alternative approach for an adaptive optics scanning laser ophthalmoscope (AO-SLO). In contrast to other commonly used AO-SLO instruments, the imaging optics consist of lenses. Images of the fovea region of 5 healthy volunteers are recorded. The system is capable to resolve human foveal cones in 3 out of 5 healthy volunteers. Additionally, we investigated the capability of the system to support larger scanning angles (up to 5°) on the retina. Finally, in order to demonstrate the performance of the instrument images of rod photoreceptors are presented.

  13. Multifunction laser source for ground and airborne applications

    NASA Astrophysics Data System (ADS)

    Crépy, Bruno

    2011-06-01

    Multiple ground and airborne vehicles could share common and multifunctional laser modules. The host system constraints and requirements have similarities making a laser modular concept interesting. Among the desired functions, the core ones are the designation and the rangefinding capabilities. A diode pumped laser source at 1μm with a switchable OPO stage for wavelength conversion fully satisfies the designation and rangefinding tasks. Over the last years, CILAS has developed the key technologies for the improvement of the main system parameters with the imperative constraints to be International Traffic in Arm Regulations Free (ITAR Free). Particularly, this novel architecture avoids thermo electric cooler (TEC) generally used to stabilise the wavelength of the laser diode pump source within the entire operational thermal range.

  14. The airborne laser ranging system, its capabilities and applications

    NASA Technical Reports Server (NTRS)

    Kahn, W. D.; Degnan, J. J.; Englar, T. S., Jr.

    1982-01-01

    The airborne laser ranging system is a multibeam short pulse laser ranging system on board an aircraft. It simultaneously measures the distances between the aircraft and six laser retroreflectors (targets) deployed on the Earth's surface. The system can interrogate over 100 targets distributed over an area of 25,000 sq, kilometers in a matter of hours. Potentially, a total of 1.3 million individual range measurements can be made in a six hour flight. The precision of these range measurements is approximately + or - 1 cm. These measurements are used in procedure which is basically an extension of trilateration techniques to derive the intersite vector between the laser ground targets. By repeating the estimation of the intersite vector, strain and strain rate errors can be estimated. These quantities are essential for crustal dynamic studies which include determination and monitoring of regional strain in the vicinity of active fault zones, land subsidence, and edifice building preceding volcanic eruptions.

  15. Extraction of power lines from mobile laser scanning data

    NASA Astrophysics Data System (ADS)

    Xiang, Qing; Li, Jonathan; Wen, Chenglu; Huang, Pengdi

    2016-03-01

    Modern urban life is becoming increasingly more dependent on reliable electric power supply. Since power outages cause substantial financial losses to producers, distributors and consumers of electric power, it is in the common interest to minimize failures of power lines. In order to detect defects as early as possible and to plan efficiently the maintenance activities, distribution networks are regularly inspected. Carrying out foot patrols or climbing the structures to visually inspect transmission lines and aerial surveys (e.g., digital imaging or most recent airborne laser scanning (ALS) are the two most commonly used methods of power line inspection. Although much faster in comparison to the foot patrol inspection, aerial inspection is more expensive and usually less accurate, in complex urban areas particularly. This paper presents a scientific work that is done in the use of mobile laser scanning (MLS) point clouds for automated extraction of power lines. In the proposed method, 2D power lines are extracted using Hough transform in the projected XOY plane and the 3D power line points are visualized after the point searching. Filtering based on an elevation threshold is applied, which is combined with the vehicle's trajectory in the horizontal section.

  16. Airborne tunable diode laser spectrometer for trace-gas measurement in the lower stratosphere.

    PubMed

    Podolske, J; Loewenstein, M

    1993-09-20

    This paper describes the airborne tunable laser absorption spectrometer, a tunable diode laser instrument designed for in situ trace-gas measurement in the lower stratosphere from an ER-2 high-altitude research aircraft. Laser-wavelength modulation and second-harmonic detection are employed to achieve the required constituent detection sensitivity. The airborne tunable laser absorption spectrometer was used in two polar ozone campaigns, the Airborne Antarctic Ozone Experiment and the Airborne Arctic Stratospheric Expedition, and measured nitrous oxide with a response time of Is and an accuracy ≤ 10%.

  17. Airborne laser topographic mapping results from initial joint NASA/US Army Corps of Engineers experiment

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Collins, J. G.; Swift, R. N.; Butler, M. L.

    1980-01-01

    Initial results from a series of joint NASA/US Army Corps of Engineers experiments are presented. The NASA Airborne Oceanographic Lidar (AOL) was exercised over various terrain conditions, collecting both profile and scan data from which river basin cross sections are extracted. Comparisons of the laser data with both photogrammetry and ground surveys are made, with 12 to 27 cm agreement observed over open ground. Foliage penetration tests, utilizing the unique time-waveform sampling capability of the AOL, indicate 50 cm agreement with photogrammetry (known to have difficulty in foliage covered terrain).

  18. Nonlinear femtosecond laser induced scanning tunneling microscopy.

    PubMed

    Dey, Shirshendu; Mirell, Daniel; Perez, Alejandro Rodriguez; Lee, Joonhee; Apkarian, V Ara

    2013-04-21

    We demonstrate ultrafast laser driven nonlinear scanning tunneling microscopy (STM), under ambient conditions. The design is an adaptation of the recently introduced cross-polarized double beat method, whereby z-polarized phase modulated fields are tightly focused at a tunneling junction consisting of a sharp tungsten tip and an optically transparent gold film as substrate. We demonstrate the prerequisites for ultrafast time-resolved STM through an operative mechanism of nonlinear laser field-driven tunneling. The spatial resolution of the nonlinear laser driven STM is determined by the local field intensity. Resolution of 0.3 nm-10 nm is demonstrated for the intensity dependent, exponential tunneling range. The demonstration is carried out on a junction consisting of tungsten tip and gold substrate. Nano-structured gold is used for imaging purposes, to highlight junction plasmon controlled tunneling in the conductivity limit.

  19. Two-Photon Laser Scanning Microscopy

    NASA Astrophysics Data System (ADS)

    Nimmerjahn, A.; Theer, P.; Helmchen, F.

    Since its inception more than 15 years ago, two-photon laser scanning microscopy (2PLSM) has found widespread use in biological and medical research. Two-photon microscopy is based on simultaneous absorption of two photons by fluorophores and subsequent fluorescence emission, a process which under normal illumination conditions is highly improbable. Theoretically described around 1930 by Maria Göppert-Mayer [1], the first experimental demonstration of two-photon excitation had to await the invention of the laser, which produced sufficiently high light intensities to observe two-photon absorption events [2]. Only after the development of ultrafast lasers providing subpicosecond light pulses with high peak power intensities, however, two-photon-excited fluorescence became practical in a laser-scanning microscope [3]. Since then 2PLSM has developed into the method of choice for high-resolution imaging in living animals (reviewed in [4,5]). One of the main reasons is the low sensitivity of 2PLSM to light scattering, which enables imaging relatively deep inside biological tissue and direct observation of the dynamic behavior of cells in their native environment. In this chapter, we introduce the physical principles governing 2PLSM and briefly describe the key instrument components. We give an overview of fluorescence labeling techniques and how they are combined with 2PLSM for functional imaging and photomanipulation in living tissue. Finally, we discuss limitations and provide some future perspectives.

  20. Alexandrite laser transmitter development for airborne water vapor DIAL measurements

    NASA Technical Reports Server (NTRS)

    Chyba, Thomas H.; Ponsardin, Patrick; Higdon, Noah S.; DeYoung, Russell J.; Browell, Edward V.

    1995-01-01

    In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned 'on' and 'off' a water vapor absorption line. Desired characteristics of the on-line transmitted laser beam include: pulse energy greater than or equal to 100 mJ, high-resolution tuning capability (uncertainty less than 0.25 pm), good spectral stability (jitter less than 0.5 pm about the mean), and high spectral purity (greater than 99 percent). The off-line laser is generally detuned less than 100 pm away from the water vapor line. Its spectral requirements are much less stringent. In our past research, we developed and demonstrated the airborne DIAL technique for water vapor measurements in the 720-nm spectral region using a system based on an alexandrite laser as the transmitter for the on-line wavelength and a Nd:YAG laser-pumped dye laser for the off-line wavelength. This off-line laser has been replaced by a second alexandrite laser. Diode lasers are used to injection seed both lasers for frequency and linewidth control. This eliminates the need for the two intracavity etalons utilized in our previous alexandrite laser and thereby greatly reduces the risk of optical damage. Consequently, the transmitted pulse energy can be substantially increased, resulting in greater measurement range, higher data density, and increased measurement precision. In this paper, we describe the diode injection seed source, the two alexandrite lasers, and the device used to line lock the on-line seed source to the water vapor absorption feature.

  1. An Automatic Algorithm for Minimizing Anomalies and Discrepancies in Point Clouds Acquired by Laser Scanning Technique

    NASA Astrophysics Data System (ADS)

    Bordin, Fabiane; Gonzaga, Luiz, Jr.; Galhardo Muller, Fabricio; Veronez, Mauricio Roberto; Scaioni, Marco

    2016-06-01

    Laser scanning technique from airborne and land platforms has been largely used for collecting 3D data in large volumes in the field of geosciences. Furthermore, the laser pulse intensity has been widely exploited to analyze and classify rocks and biomass, and for carbon storage estimation. In general, a laser beam is emitted, collides with targets and only a percentage of emitted beam returns according to intrinsic properties of each target. Also, due interferences and partial collisions, the laser return intensity can be incorrect, introducing serious errors in classification and/or estimation processes. To address this problem and avoid misclassification and estimation errors, we have proposed a new algorithm to correct return intensity for laser scanning sensors. Different case studies have been used to evaluate and validated proposed approach.

  2. Three-dimensional environment models from airborne laser radar data

    NASA Astrophysics Data System (ADS)

    Soderman, Ulf; Ahlberg, Simon; Elmqvist, Magnus; Persson, Asa

    2004-09-01

    Detailed 3D environment models for visualization and computer based analyses are important in many defence and homeland security applications, e.g. crisis management, mission planning and rehearsal, damage assessment, etc. The high resolution data from airborne laser radar systems for 3D sensing provide an excellent source of data for obtaining the information needed for many of these models. To utilise the 3D data provided by the laser radar systems however, efficient methods for data processing and environment model construction needs to be developed. In this paper we will present some results on the development of laser data processing methods, including methods for data classification, bare earth extraction, 3D-reconstruction of buildings, and identification of single trees and estimation of their position, height, canopy size and species. We will also show how the results can be used for the construction of detailed 3D environment models for military modelling and simulation applications. The methods use data from discrete return airborne laser radar systems and digital cameras.

  3. NASA DC-8 Airborne Scanning Lidar Cloud and Contrail Observations

    NASA Technical Reports Server (NTRS)

    Uthe, Edward E.; Oseberg, Terje E.; Nielsen, Norman B.

    1997-01-01

    An angular scanning backscatter lidar has been developed and operated from the NASA DC-8 aircraft; the lidar viewing direction could be scanned from vertically upward to forward in the direction of aircraft travel to vertically downward. The scanning lidar was used to generate real-time video displays of clouds and contrails above, below, and ahead of the aircraft to aid in positioning the aircraft for achieving optimum cloud/contrail sampling by onboard in situ samplers. Data examples show that the lidar provides unique information for the interpretation of the other data records and that combined data analyses provides enhanced evaluations of contrail/cloud structure, dynamics, composition, and optical/radiative properties.

  4. NCALM: NSF Supported Center for Airborne Laser Mapping

    NASA Astrophysics Data System (ADS)

    Shrestha, R. L.; Carter, W. E.; Dietrich, W. E.

    2003-12-01

    The National Science Foundation (NSF) recently awarded a grant to create a research center to support the use of airborne laser mapping technology in the scientific community. The NSF supported Center for Airborne Laser Mapping (NCALM) will be operated jointly by the Department of Civil & Coastal Engineering, College of Engineering, University of Florida (UF) and the Department of Earth and Planetary Science, University of California-Berkeley (UCB). NCALM will use the Airborne Laser Swath Mapping (ALSM) system jointly owned by UF and Florida International University (FIU), based at the UF Geosensing Engineering and Mapping (GEM) Research Center. The state-of-the-art laser surveying instrumentation, GPS systems, which are installed in a Cessna 337 Skymaster aircraft, will collect research grade data in areas selected through the competitive NSF grant review process. The ALSM observations will be analyzed both at UF and UCB, and made available to the PI through an archiving and distribution center at UCB-building upon the Berkeley Seismological Laboratory (BSL) Northern California Earthquake Data Center system. The purpose of NCALM is to provide research grade data from ALSM technology to NSF supported research studies in geosciences. The Center will also contribute to software development that will increase the processing speed and data accuracy. This presentation will discuss NCALM operation and the process of submitting proposals to NSF. In addition, it will outline the process to request available NCALM seed project funds to help jump-start small scientific research studies. Funds are also available for travel by academic researchers and students for hands-on knowledge and experience in ALSM technology at UF and UCB.

  5. Assessment of long-range kinematic GPS positioning errors by comparison with airborne laser altimetry and satellite altimetry

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaohong; Forsberg, Rene

    2007-03-01

    Long-range airborne laser altimetry and laser scanning (LIDAR) or airborne gravity surveys in, for example, polar or oceanic areas require airborne kinematic GPS baselines of many hundreds of kilometers in length. In such instances, with the complications of ionospheric biases, it can be a real challenge for traditional differential kinematic GPS software to obtain reasonable solutions. In this paper, we will describe attempts to validate an implementation of the precise point positioning (PPP) technique on an aircraft without the use of a local GPS reference station. We will compare PPP solutions with other conventional GPS solutions, as well as with independent data by comparison of airborne laser data with “ground truth” heights. The comparisons involve two flights: A July 5, 2003, airborne laser flight line across the North Atlantic from Iceland to Scotland, and a May 24, 2004, flight in an area of the Arctic Ocean north of Greenland, near-coincident in time and space with the ICESat satellite laser altimeter. Both of these flights were more than 800 km long. Comparisons between different GPS methods and four different software packages do not suggest a clear preference for any one, with the heights generally showing decimeter-level agreement. For the comparison with the independent ICESat- and LIDAR-derived “ground truth” of ocean or sea-ice heights, the statistics of comparison show a typical fit of around 10 cm RMS in the North Atlantic, and 30 cm in the sea-ice region north of Greenland. Part of the latter 30 cm error is likely due to errors in the airborne LIDAR measurement and calibration, as well as errors in the “ground truth” ocean surfaces due to drifting sea-ice. Nevertheless, the potential of the PPP method for generating 10 cm level kinematic height positioning over long baselines is illustrated.

  6. Patterned retinal coagulation with a scanning laser

    NASA Astrophysics Data System (ADS)

    Palanker, Daniel; Jain, ATul; Paulus, Yannis; Andersen, Dan; Blumenkranz, Mark S.

    2007-02-01

    Pan-retinal photocoagulation in patients with diabetic retinopathy typically involves application of more than 1000 laser spots; often resulting in physician fatigue and patient discomfort. We present a semi-automated patterned scanning laser photocoagulator that rapidly applies predetermined patterns of lesions; thus, greatly improving the comfort, efficiency and precision of the treatment. Patterns selected from a graphical user interface are displayed on the retina with an aiming beam, and treatment can be initiated and interrupted by depressing a foot pedal. To deliver a significant number of burns during the eye's fixation time, each pulse should be considerably shorter than conventional 100ms pulse duration. We measured coagulation thresholds and studied clinical and histological outcomes of the application of laser pulses in the range of 1-200ms in pigmented rabbits. Laser power required for producing ophthalmoscopically visible lesions with a laser spot of 132μm decreased from 360 to 37mW with pulse durations increasing from 1 to 100ms. In the range of 10-100ms clinically and histologically equivalent light burns could be produced. The safe therapeutic range of coagulation (ratio of the laser power required to produce a rupture to that for a light burn) decreased with decreasing pulse duration: from 3.8 at 100ms, to 3.0 at 20ms, to 2.5 at 10ms, and to 1.1 at 1ms. Histology demonstrated increased confinement of the thermal damage with shorter pulses, with coagulation zone limited to the photoreceptor layer at pulses shorter than 10ms. Durations of 10-20ms appear to be a good compromise between the speed and safety of retinal coagulation. Rapid application of multiple lesions greatly improves the speed, precision, and reduces pain in retinal photocoagulation.

  7. Slate characterization using 3D laser scanning

    NASA Astrophysics Data System (ADS)

    López, M.; Taboada, J.; Martínez, J.; Matías, J. M.; Vilán, J. A.

    2012-12-01

    Quality control is a necessary component of the slate slab manufacturing process so as to evaluate defects as defined by the current standard for slate. Quality control has traditionally been performed manually by an expert in the field, with the consequent human subjectivity. We studied the feasibility of using a 3D laser scanner to measure slate slabs and analyze possible defects that would lead to the rejection of slabs for particular industrial processes. The application requires slate characterization to be performed in real time and thereby requires a short computation time. We describe an optimized calibration method based on Tsai's approach that reduces calculation complexity and cost in this key 3D laser scanning stage. Configured and implemented for slate slab characterization, the system produces the required information in real time during the production process.

  8. Laser-jamming effectiveness analysis of combined-fiber lasers for airborne defense systems.

    PubMed

    Jie, Xu; Shanghong, Zhao; Rui, Hou; Shengbao, Zhan; Lei, Shi; Jili, Wu; Shaoqiang, Fang; Yongjun, Li

    2008-12-20

    The laser-jamming effectiveness of combined fiber lasers for airborne defense systems is analyzed in detail. Our preliminary experimental results are proof of the concept of getting a high-power laser through a beam combination technique. Based on combined fiber lasers, the jamming effectiveness of four-quadrant guidance and imaging guidance systems are evaluated. The simulation results have proved that for a four-quadrant guidance system, the tracking system takes only two seconds to complete tracking, and the new tracking target is the jamming laser; for the imaging guidance system, increasing the power of the jamming laser or the distance between the target and the jamming laser are both efficient ways to achieve a successful laser jamming.

  9. Laser scanning system for object monitoring

    DOEpatents

    McIntyre, Timothy James [Knoxville, TN; Maxey, Lonnie Curtis [Powell, TN; Chiaro, Jr; John, Peter [Clinton, TN

    2008-04-22

    A laser scanner is located in a fixed position to have line-of-sight access to key features of monitored objects. The scanner rapidly scans pre-programmed points corresponding to the positions of retroreflecting targets affixed to the key features of the objects. The scanner is capable of making highly detailed scans of any portion of the field of view, permitting the exact location and identity of targets to be confirmed. The security of an object is verified by determining that the cooperative target is still present and that its position has not changed. The retroreflecting targets also modulate the reflected light for purposes of returning additional information back to the location of the scanner.

  10. Damage detection using scanning laser vibrometer

    NASA Astrophysics Data System (ADS)

    Chen, Shen-En; Venkatappa, Suhas; Petro, Samer H.; Gangarao, Hota V.

    1998-06-01

    A damage detection algorithm based on the principle of curvature changes has been developed at CFC-WVU. However, the algorithm requires accurate mode shapes with adequate spatial density. Existing contact sensors can not provide adequate spatial density without adding excessive mass. Hence, non-contact scanning techniques, such as scanning laser vibrometer (SLV) has adequate sensitivity and accuracy is yet to be proven. The applicability of SLV on large structures is also questionable. To assess the suitability of using SLV for damage detection, a beam specimen has been tested using an existing system. The results confirm that damage detection using vibration measurements from SLV is successful. Due to more spatial density, the SLV data is shown to be more sensitive than the contact sensor test.

  11. Airborne laser altimetry survey of Glaciar Tyndall, Patagonia

    NASA Astrophysics Data System (ADS)

    Keller, Kristian; Casassa, Gino; Rivera, Andrés; Forsberg, Rene; Gundestrup, Niels

    2007-10-01

    The first airborne laser altimetry measurements of a glacier in South America are presented. Data were collected in November of 2001 over Glaciar Tyndall, Torres del Paine National Park, Chilean Patagonia, onboard a Twin Otter airplane of the Chilean Air Force. A laser scanner with a rotating polygon-mirror system together with an Inertial Navigation System (INS) were fixed to the floor of the aircraft, and used in combination with two dual-frequency GPS receivers. Together, the laser-INS-GPS system had a nominal accuracy of 30 cm after data processing. On November 23rd, a total of 235 km were flown over the ablation area of Glaciar Tyndall, with 5 longitudinal tracks with a mean swath width of 300 m, which results in a point spacing of approximately 2 m both along and across track. A digital elevation model (DEM) generated using the laser altimetry data was compared with a DEM produced from a 1975 map (1:50,000 scale — Instituto Geográfico Militar (IGM), Chile). A mean thinning of - 3.1 ± 1.0 m a - 1 was calculated for the ablation area of Glaciar Tyndall, with a maximum value of - 7.7 ± 1.0 m a - 1 at the calving front at 50 m a.s.l. and minimum values of between - 1.0 and - 2.0 ± 1.0 m a - 1 at altitudes close to the equilibrium line altitude (900 m a.s.l.). The thinning rates derived from the airborne survey were similar to the results obtained by means of ground survey carried out at ˜ 600 m of altitude on Glaciar Tyndall between 1975 and 2002, yielding a mean thinning of - 3.2 m a - 1 [Raymond, C., Neumann, T.A., Rignot, E., Echelmeyer, K.A., Rivera, A., Casassa, G., 2005. Retreat of Tyndall Glacier, Patagonia, over the last half century. Journal of Glaciology 173 (51), 239-247.]. A good agreement was also found between ice elevation changes measured with laser data and previous results obtained with Shuttle Radar Topography Mission (SRTM) data. We conclude that airborne laser altimetry is an effective means for accurately detecting glacier elevation

  12. Feature-constrained registration of building point clouds acquired by terrestrial and airborne laser scanners

    NASA Astrophysics Data System (ADS)

    Wu, Hangbin; Scaioni, Marco; Li, Hanyan; Li, Nan; Lu, Minfeng; Liu, Chun

    2014-01-01

    Point-cloud registration is usually accomplished on the basis of several corresponding features to compute the parameters of the transformation model. However, common point features are difficult to select because airborne laser scanner (ALS) and terrestrial laser scanner (TLS) point clouds of the same object have be aligned due to the different sensing positions and sampling modes. Taking building profile features as objects, a registration method based on feature constraints is proposed here. The standard six-parameter rigid-body transformation adopted for alignment of laser scans is replaced by a two-step transformation: horizontal registration based on a two-dimensional similarity transformation and vertical registration based on a simple vertical shift. First, the feature-line and feature-plane equation parameters are obtained from both the airborne and terrestrial point clouds. Second, the plane transformation parameters are computed after projecting the extracted features onto a horizontal reference plane. Finally, the elevation transformation parameter is calculated by comparing the heights of flat features. The ALS and TLS datasets of two buildings (Shanghai Pudong International Conference Center and Shanghai Ocean Aquarium, China) were used to evaluate the robustness and accuracy. The results show that the proposed feature-constrained method works well for registration between two datasets. Five checkpoints and one overlap zone for the Pudong International Conference Center were selected to evaluate the accuracy and resulted in accuracies of 0.15 to 0.5 m in the horizontal direction and 0.20 m in the vertical direction.

  13. Airborne molecular contamination: quality criterion for laser and optical components

    NASA Astrophysics Data System (ADS)

    Otto, Michael

    2015-02-01

    Airborne molecular contaminations (AMCs) have been recognized as a major problem in semiconductor fabrication. Enormous technical and financial efforts are made to remove or at least reduce these contaminations in production environments to increase yield and process stability. It can be shown that AMCs from various sources in laser devices have a negative impact on quality and lifetime of lasers and optical systems. Outgassing of organic compounds, especially condensable compounds were identified as the main source for deterioration of optics. These compounds can lead to hazing on surfaces of optics, degradation of coating, reducing the signal transmission or the laser signal itself and can enhance the probability of laser failure and damage. Sources of organic outgassing can be molding materials, resins, seals, circuit boards, cable insulation, coatings, paints and others. Critical compounds are siloxanes, aromatic amines and high boiling aromatic hydrocarbons like phthalates which are used as softeners in plastic materials. Nowadays all sensitive assembly steps are performed in controlled cleanroom environments to reduce risks of contamination. We will demonstrate a high efficient air filter concept to remove AMCs for production environments with special AMC filters and methods for the qualification and monitoring of these environments. Additionally, we show modern techniques and examples for the pre-qualification of materials. For assembled components, we provide sampling concepts for a routine measurement for process, component and product qualification. A careful selection of previously tested and certified materials and components is essential to guarantee the quality of lasers and optical devices.

  14. Airborne laser systems for atmospheric sounding in the near infrared

    NASA Astrophysics Data System (ADS)

    Sabatini, Roberto; Richardson, Mark A.; Jia, Huamin; Zammit-Mangion, David

    2012-06-01

    This paper presents new techniques for atmospheric sounding using Near Infrared (NIR) laser sources, direct detection electro-optics and passive infrared imaging systems. These techniques allow a direct determination of atmospheric extinction and, through the adoption of suitable inversion algorithms, the indirect measurement of some important natural and man-made atmospheric constituents, including Carbon Dioxide (CO2). The proposed techniques are suitable for remote sensing missions performed by using aircraft, satellites, Unmanned Aerial Vehicles (UAV), parachute/gliding vehicles, Roving Surface Vehicles (RSV), or Permanent Surface Installations (PSI). The various techniques proposed offer relative advantages in different scenarios. All are based on measurements of the laser energy/power incident on target surfaces of known geometric and reflective characteristics, by means of infrared detectors and/or infrared cameras calibrated for radiance. Experimental results are presented relative to ground and flight trials performed with laser systems operating in the near infrared (NIR) at λ = 1064 nm and λ = 1550 nm. This includes ground tests performed with 10 Hz and 20 KHz PRF NIR laser systems in a variety of atmospheric conditions, and flight trials performed with a 10 Hz airborne NIR laser system installed on a TORNADO aircraft, flying up to altitudes of 22,000 ft above ground level. Future activities are planned to validate the atmospheric retrieval algorithms developed for CO2 column density measurements, with emphasis on aircraft related emissions at airports and other high air-traffic density environments.

  15. Mobile Laser Scanning for Indoor Modelling

    NASA Astrophysics Data System (ADS)

    Thomson, C.; Apostolopoulos, G.; Backes, D.; Boehm, J.

    2013-10-01

    The process of capturing and modelling buildings has gained increased focus in recent years with the rise of Building Information Modelling (BIM). At the heart of BIM is a process change for the construction and facilities management industries whereby a BIM aids more collaborative working through better information exchange, and as a part of the process Geomatic/Land Surveyors are not immune from the changes. Terrestrial laser scanning has been proscribed as the preferred method for rapidly capturing buildings for BIM geometry. This is a process change from a traditional measured building survey just with a total station and is aided by the increasing acceptance of point cloud data being integrated with parametric building models in BIM tools such as Autodesk Revit or Bentley Architecture. Pilot projects carried out previously by the authors to investigate the geometry capture and modelling of BIM confirmed the view of others that the process of data capture with static laser scan setups is slow and very involved requiring at least two people for efficiency. Indoor Mobile Mapping Systems (IMMS) present a possible solution to these issues especially in time saved. Therefore this paper investigates their application as a capture device for BIM geometry creation over traditional static methods through a fit-for-purpose test.

  16. Complementing airborne laser bathymetry with UAV-based lidar for capturing alluvial landscapes

    NASA Astrophysics Data System (ADS)

    Mandlburger, Gottfried; Pfennigbauer, Martin; Riegl, Ursula; Haring, Alexander; Wieser, Martin; Glira, Philipp; Winiwarter, Lukas

    2015-10-01

    In this paper we report on a flight experiment employing airborne laser bathymetry (ALB) and unmanned aerial vehicle (UAV) based laser scanning (ULS) for capturing very high resolution topography of shallow water areas and the surrounding littoral zone at the pre-alpine Pielach River in Austria. The aim of the research is to assess how information gained from non-bathymetric, ultra-high resolution ULS can support the ALB data. We focus first on the characterization of the water surface of a lowland river and provide validation results using the data of a topographic airborne laser scanning (ALS) sensor and a low flying ULS system. By repeat ULS survey of a the meandering river reach we are able to quantify short-term water level changes due to surface waves in high resolution. Based on a hydrodynamic-numerical (HN) model we assess the accuracy of the water surface derived from a water penetrating ALB sensor. In the second part of the paper we investigate the ability of ALB, ALS, and ULS to describe the complex topography and vegetation structure of the alluvial area. This is carried out by comparing the Digital Terrain Models (DTM) derived from different sensor configurations. Finally we demonstrate the potential of ULS for estimating single tree positions and stem diameters for detailed floodplain roughness characterization in HN simulations. The key findings are: (i) NIR scan data from ALS or ULS provide more precise water level height estimates (no bias, 1σ: 2 cm) compared to ALB (bias: 3 cm, 1σ: 4 cm), (ii) within the studied reach short-term water level dynamics irrelevant for ALB data acquisition considering a 60 cm footprint diameter, and (iii) stem diameters can be estimated based on ULS point clouds but not from ALS and ALB.

  17. MEMS scanned laser head-up display

    NASA Astrophysics Data System (ADS)

    Freeman, Mark O.

    2011-03-01

    Head-up displays (HUD) in automobiles and other vehicles have been shown to significantly reduce accident rates by keeping the driver's eyes on the road. The requirements for automotive HUDs are quite demanding especially in terms of brightness, dimming range, supplied power, and size. Scanned laser display technology is particularly well-suited to this application since the lasers can be very efficiently relayed to the driver's eyes. Additionally, the lasers are only turned on where the light is needed in the image. This helps to provide the required brightness while minimizing power and avoiding a background glow that disturbs the see-through experience. Microvision has developed a couple of HUD architectures that are presented herein. One design uses an exit pupil expander and relay optics to produce a high quality virtual image for built-in systems where the image appears to float above the hood of the auto. A second design uses a patented see-through screen technology and pico projector to make automotive HUDs available to anyone with a projector. The presentation will go over the basic designs for the two types of HUD and discuss design tradeoffs.

  18. Nd:YLF laser for airborne/spaceborne laser ranging

    NASA Technical Reports Server (NTRS)

    Dallas, Joseph L.; Selker, Mark D.

    1993-01-01

    In order to meet the need for light weight, long lifetime, efficient, short pulse lasers, a diode-pumped, Nd:YLF oscillator and regenerative amplifier is being developed. The anticipated output is 20 mJ per 10 picosecond pulse, running at a repetition rate of 40 Hz. The fundamental wavelength is at 1047 nm. The oscillator is pumped by a single laser diode bar and mode locked using an electro-optic, intra-cavity phase modulator. The output from the oscillator is injected as a seed into the regenerative amplifier. The regenerative amplifier laser crystal is optically pumped by two 60W quasi-cw laser diode bars. Each diode is collimated using a custom designed micro-lens bar. The injected 10 ps pulse from the oscillator is kept circulating within the regenerative amplifier until this nanojoule level seed pulse is amplified to 2-3 millijoules. At this point the pulse is ejected and sent on to a more standard single pass amplifier where the energy is boosted to 20 mJ. The footprint of the entire laser (oscillator-regenerative amplifier-amplifier) will fit on a 3 by 4 ft. optical pallet.

  19. Scanning Optics Enabled Possibilities and Challenges in Laser Cladding

    NASA Astrophysics Data System (ADS)

    Pekkarinen, Joonas

    Laser cladding using a scanned beam is quite a similar process than laser cladding using static optics (e.g. lens or mirror optics). The main difference comes from the manipulation of the laser beam. In laser cladding with scanning optics the laser beam is manipulated with a scanner so that the laser's area of influence can be shaped numerically. This increases cladding process flexibility. Scanning optics enable laser beam modification considerably versatile way than normal static optics can. This is due to possibility of numerical adjustment of scanning amplitude, laser power and scanning frequency. By modifying these parameters clad beads geometry can by modified quite freely. However scanned laser beam in surface modification process creates some restricting factors to the process. Mainly limitations for the process parameter values come from the dual characteristics of the energy input. This paper treats usability of scanning optics in laser cladding process in general level. In this paper is discussed how scanned beam can be used to increase the flexibility but also maters that limit the usage of scanned beam in cladding process. Process possibilities and limitations are presented in trough experimental data and examples.

  20. An Airborne Conical Scanning Millimeter-Wave Imaging Radiometer (CoSMIR)

    NASA Technical Reports Server (NTRS)

    Piepmeier, J.; Racette, P.; Wang, J.; Crites, A.; Doiron, T.; Engler, C.; Lecha, J.; Powers, M.; Simon, E.; Triesky, M.; Krebs, Carolyn A. (Technical Monitor)

    2001-01-01

    An airborne Conical Scanning Millimeter-wave Imaging Radiometer (CoSMIR) for high-altitude observations from the NASA Research Aircraft (ER-2) is discussed. The primary application of the CoSMIR is water vapor profile remote sensing. Four radiometers operating at 50 (three channels), 92, 150, and 183 (three channels) GHz provide spectral coverage identical to nine of the Special Sensor Microwave Imager/Sounder (SSMIS) high-frequency channels. Constant polarization-basis conical and cross-track scanning capabilities are achieved using an elevation-under-azimuth two-axis gimbals.

  1. Terrestrial Laser Scanning for Vegetation Sampling

    PubMed Central

    Richardson, Jeffrey J; Moskal, L. Monika; Bakker, Jonathan D.

    2014-01-01

    We developed new vegetation indices utilizing terrestrial laser scanning (TLS) to quantify the three-dimensional spatial configuration of plant communities. These indices leverage the novelty of TLS data and rely on the spatially biased arrangement of a TLS point cloud. We calculated these indices from TLS data acquired within an existing long term manipulation of forest structure in Central Oregon, USA, and used these data to test for differences in vegetation structure. Results provided quantitative evidence of a significant difference in vegetation density due to thinning and burning, and a marginally significant difference in vegetation patchiness due to grazing. A comparison to traditional field sampling highlighted the novelty of the TLS based method. By creating a linkage between traditional field sampling and landscape ecology, these indices enable field investigations of fine-scale spatial patterns. Applications include experimental assessment, long-term monitoring, and habitat characterization. PMID:25353981

  2. Terrestrial laser scanning for vegetation sampling.

    PubMed

    Richardson, Jeffrey J; Moskal, L Monika; Bakker, Jonathan D

    2014-10-28

    We developed new vegetation indices utilizing terrestrial laser scanning (TLS) to quantify the three-dimensional spatial configuration of plant communities. These indices leverage the novelty of TLS data and rely on the spatially biased arrangement of a TLS point cloud. We calculated these indices from TLS data acquired within an existing long term manipulation of forest structure in Central Oregon, USA, and used these data to test for differences in vegetation structure. Results provided quantitative evidence of a significant difference in vegetation density due to thinning and burning, and a marginally significant difference in vegetation patchiness due to grazing. A comparison to traditional field sampling highlighted the novelty of the TLS based method. By creating a linkage between traditional field sampling and landscape ecology, these indices enable field investigations of fine-scale spatial patterns. Applications include experimental assessment, long-term monitoring, and habitat characterization.

  3. The Laser Vegetation Imaging Sensor (LVIS): An Airborne Laser Altimeter for Mapping Vegetation and Topography

    NASA Technical Reports Server (NTRS)

    Bryan, J.; Rabine, David L.

    1998-01-01

    The Laser Vegetation Imaging Sensor (LVIS) is an airborne laser altimeter designed to quickly and extensively map surface topography as well as the relative heights of other reflecting surfaces within the laser footprint. Since 1997, this instrument has primarily been used as the airborne simulator for the Vegetation Canopy Lidar (VCL) mission, a spaceborne mission designed to measure tree height, vertical structure and ground topography (including sub-canopy topography). LVIS is capable of operating from 500 m to 10 km above ground level with footprint sizes from 1 to 60 m. Laser footprints can be randomly spaced within the 7 degree telescope field-of-view, constrained only by the operating frequency of the ND:YAG Q-switched laser (500 Hz). A significant innovation of the LVIS altimeter is that all ranging, waveform recording, and range gating are performed using a single digitizer, clock base, and detector. A portion of the outgoing laser pulse is fiber-optically fed into the detector used to collect the return signal and this entire time history of the outgoing and return pulses is digitized at 500 Msamp/sec. The ground return is then located using software digital signal processing, even in the presence of visibly opaque clouds. The surface height distribution of all reflecting surfaces within the laser footprint can be determined, for example, tree height and ground elevation. To date, the LVIS system has been used to monitor topographic change at Long Valley caldera, CA, as part of NASA's Topography and Surface Change program, and to map tree structure and sub-canopy topography at the La Selva Biological Research Station in Costa Rica, as part of the pre-launch calibration activities for the VCL mission. We present results that show the laser altimeter consistently and accurately maps surface topography, including sub-canopy topography, and vegetation height and structure. These results confirm the measurement concept of VCL and highlight the benefits of

  4. Automatic change detection using mobile laser scanning

    NASA Astrophysics Data System (ADS)

    Hebel, M.; Hammer, M.; Gordon, M.; Arens, M.

    2014-10-01

    Automatic change detection in 3D environments requires the comparison of multi-temporal data. By comparing current data with past data of the same area, changes can be automatically detected and identified. Volumetric changes in the scene hint at suspicious activities like the movement of military vehicles, the application of camouflage nets, or the placement of IEDs, etc. In contrast to broad research activities in remote sensing with optical cameras, this paper addresses the topic using 3D data acquired by mobile laser scanning (MLS). We present a framework for immediate comparison of current MLS data to given 3D reference data. Our method extends the concept of occupancy grids known from robot mapping, which incorporates the sensor positions in the processing of the 3D point clouds. This allows extracting the information that is included in the data acquisition geometry. For each single range measurement, it becomes apparent that an object reflects laser pulses in the measured range distance, i.e., space is occupied at that 3D position. In addition, it is obvious that space is empty along the line of sight between sensor and the reflecting object. Everywhere else, the occupancy of space remains unknown. This approach handles occlusions and changes implicitly, such that the latter are identifiable by conflicts of empty space and occupied space. The presented concept of change detection has been successfully validated in experiments with recorded MLS data streams. Results are shown for test sites at which MLS data were acquired at different time intervals.

  5. A simulator for airborne laser swath mapping via photon counting

    NASA Astrophysics Data System (ADS)

    Slatton, K. C.; Carter, W. E.; Shrestha, R.

    2005-06-01

    Commercially marketed airborne laser swath mapping (ALSM) instruments currently use laser rangers with sufficient energy per pulse to work with return signals of thousands of photons per shot. The resulting high signal to noise level virtually eliminates spurious range values caused by noise, such as background solar radiation and sensor thermal noise. However, the high signal level approach requires laser repetition rates of hundreds of thousands of pulses per second to obtain contiguous coverage of the terrain at sub-meter spatial resolution, and with currently available technology, affords little scalability for significantly downsizing the hardware, or reducing the costs. A photon-counting ALSM sensor has been designed by the University of Florida and Sigma Space, Inc. for improved topographic mapping with lower power requirements and weight than traditional ALSM sensors. Major elements of the sensor design are presented along with preliminary simulation results. The simulator is being developed so that data phenomenology and target detection potential can be investigated before the system is completed. Early simulations suggest that precise estimates of terrain elevation and target detection will be possible with the sensor design.

  6. Estimation filters for missile tracking with airborne laser

    NASA Astrophysics Data System (ADS)

    Clemons, T. M., III; Chang, K. C.

    2006-05-01

    This paper examines the use of various estimation filters on the highly non-linear problem of tracking a ballistic missile during boost phase from a moving airborne platform. The aircraft receives passive bearing data from an IR sensor and range data from a laser rangefinder. The aircraft is assumed to have a laser weapon system that requires highly accurate bearing information in order to keep the laser on target from a distance of 100-200 km. The tracking problem is made more difficult due to the changing acceleration of the missile, especially during stage drop-off and ignition. The Extended Kalman Filter (EKF), Unscented Kalman Filter (UKF), 'bootstrap' Particle Filter (PF), and the Gaussian Sum Particle Filter (GSPF) are explored using different values for sensor accuracy in bearing and range, and various degrees of uncertainty of the target and platform dynamic. Scenarios were created using Satellite Toolkit © for trajectories from a Southeast Asia launch with associated sensor observations. MATLAB © code modified from the ReBEL Toolkit © was used to run the EKF, UKF, PF, and GSPF sensor track filters. Mean Square Error results are given for tracking during the period when the target is in view of the radar and IR sensors. This paper provides insight into the accuracy requirements of the sensors and the suitability of the given estimators.

  7. Mathematical model for light scanning system based on circular laser

    NASA Astrophysics Data System (ADS)

    Xu, Peiquan; Yao, Shun; Lu, Fenggui; Tang, Xinhua; Zhang, Wei

    2005-11-01

    A novel light scanning system based on circular laser trajectory for welding robot is developed. With the help of image processing technique, intelligent laser welding could be realized. According to laser triangulation algorithm and Scheimpflug condition, mathematical model for circular laser vision is built. This scanning system projects circular laser onto welded seams and recovers the depth of the welded seams, escapes from shortcomings of less information, explains ambiguity and single tracking direction inherent in "spot" or "line" type laser trajectory. Three-dimensional (3D) model for welded seams could be recognized after depth recovery. The imaging error is investigated also.

  8. Conceptual design of an airborne laser Doppler velocimeter system for studying wind fields associated with severe local storms

    NASA Technical Reports Server (NTRS)

    Thomson, J. A. L.; Davies, A. R.; Sulzmann, K. G. P.

    1976-01-01

    An airborne laser Doppler velocimeter was evaluated for diagnostics of the wind field associated with an isolated severe thunderstorm. Two scanning configurations were identified, one a long-range (out to 10-20 km) roughly horizontal plane mode intended to allow probing of the velocity field around the storm at the higher altitudes (4-10 km). The other is a shorter range (out to 1-3 km) mode in which a vertical or horizontal plane is scanned for velocity (and possibly turbulence), and is intended for diagnostics of the lower altitude region below the storm and in the out-flow region. It was concluded that aircraft flight velocities are high enough and severe storm lifetimes are long enough that a single airborne Doppler system, operating at a range of less than about 20 km, can view the storm area from two or more different aspects before the storm characteristics change appreciably.

  9. Evolution of Galveston Island Derived from Repeat Pass Airborne Laser Swath Mapping

    NASA Astrophysics Data System (ADS)

    Glennie, C. L.; Zhang, X.; Hartzell, P.; Hauser, D.

    2012-12-01

    Extensive landform transformations along the US Gulf Coast has created an urgent need to detect changes for disaster emergency response and preservation/restoration of coastal habitat. The dynamics of coastal zones can be quantified and mapped using the high vertical and horizontal point density airborne laser scanners (LiDAR). Using repeat pass airborne LiDAR, the geomorphic topography of Galveston Island, TX was characterized and evaluated, with emphasis on measuring pre- and post- hurricane transformations such as deposition, coastline movement, vegetation coverage and changes in man-made structures. Two airborne LiDAR datasets were utilized, from 2002 and 2010, and were verified and checked with high-resolution terrestrial laser scanning and DGPS observations. During the eight year time period between the LiDAR campaigns, Galveston Island was directly impacted by one significant hurricane, Ike in September, 2008. Change detection using bare earth models showed that the hurricane appears to be responsible for the replacement of emergent wetlands by open water and flats. Orthogonal profiles along the shoreline show a marked increase in beach elevation loss and a shoreline retreat of over 22 m in some locations over the eight year period. AGL (Above Ground Level) heights were generated from each LiDAR campaign to detect vegetation and man-made structure modifications. Using the AGL models, it is shown that Galveston Island has lost a large amount of vegetation coverage; however even with the widespread destruction of buildings from Hurricane Ike, there is still a net building gain in the study area over the eight year time frame.

  10. Speckle averaging system for laser raster-scan image projection

    DOEpatents

    Tiszauer, Detlev H.; Hackel, Lloyd A.

    1998-03-17

    The viewers' perception of laser speckle in a laser-scanned image projection system is modified or eliminated by the addition of an optical deflection system that effectively presents a new speckle realization at each point on the viewing screen to each viewer for every scan across the field. The speckle averaging is accomplished without introduction of spurious imaging artifacts.

  11. Feasibility of airborne detection of laser-induced fluorescence emissions from green terrestrial plants

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.; Yungel, J. K.

    1983-01-01

    The present investigation provides a demonstration of the feasibility of the airborne detection of the laser-induced fluorescence spectral emissions from living terrestrial grasses, shrubs, and trees using existing levels of lidar technology. Airborne studies were performed to ascertain system requirements necessary to detect laser-induced fluorescence from living terrestrial plants, to assess the practical acquisition of useful single-shot laser-induced fluorescence (LIF) waveforms over vegetative canopies, and to determine the comparative suitability of laser system, airborne platform, and terrestrial environmental parameters. The field experiment was conducted on May 3, 1982, over the northern portion of Wallops Island, VA. Attention is given to airborne lidar results and the description of laboratory investigations.

  12. Airborne laser study quantifies El Niño-induced coastal change

    USGS Publications Warehouse

    Sallenger, Asbury H.; Krabill, William; Brock, John H.; Swift, Robert; Jansen, Mark; Manizade, Serdar; Richmond, Bruce; Hampton, Monty; Eslinger, David

    1999-01-01

    Winter storms during the 1997–1998 El Niño caused extensive changes to the beaches and cliffs of the west coast of the United States, a NASA-NOAA-USGS investigation using a scanning airborne laser has found. For example, near Pacifica in central California, the cliff eroded locally as much as 10–13 m landward during the El Niño winter, at least 40 times the long term average erosion rate. However, only several hundred meters away the cliff was stable. This variability in cliff response may be related to differences in local beach changes where an accreting beach protected part of the cliff and an eroding beach exposed another part to attack by waves.

  13. Applications of Adaptive Optics Scanning Laser Ophthalmoscopy

    PubMed Central

    Roorda, Austin

    2010-01-01

    Adaptive optics (AO) describes a set of tools to correct or control aberrations in any optical system. In the eye, AO allows for precise control of the ocular aberrations. If used to correct aberrations over a large pupil, for example, cellular level resolution in retinal images can be achieved. AO systems have been demonstrated for advanced ophthalmoscopy as well as for testing and/or improving vision. In fact, AO can be integrated to any ophthalmic instrument where the optics of the eye is involved, with a scope of applications ranging from phoropters to optical coherence tomography systems. In this paper, I discuss the applications and advantages of using AO in a specific system, the adaptive optics scanning laser ophthalmoscope, or AOSLO. Since the Borish award was, in part, awarded to me because of this effort, I felt it appropriate to select this as the topic for this paper. Furthermore, users of AOSLO continue to appreciate the benefits of the technology, some of which were not anticipated at the time of development, and so it is time to revisit this topic and summarize them in a single paper. PMID:20160657

  14. SLATE: scanning laser automatic threat extraction

    NASA Astrophysics Data System (ADS)

    Clark, David J.; Prickett, Shaun L.; Napier, Ashley A.; Mellor, Matthew P.

    2016-10-01

    SLATE is an Autonomous Sensor Module (ASM) designed to work with the SAPIENT system providing accurate location tracking and classifications of targets that pass through its field of view. The concept behind the SLATE ASM is to produce a sensor module that provides a complementary view of the world to the camera-based systems that are usually used for wide area surveillance. Cameras provide a hi-fidelity, human understandable view of the world with which tracking and identification algorithms can be used. Unfortunately, positioning and tracking in a 3D environment is difficult to implement robustly, making location-based threat assessment challenging. SLATE uses a Scanning Laser Rangefinder (SLR) that provides precise (<1cm) positions, sizes, shapes and velocities of targets within its field-of-view (FoV). In this paper we will discuss the development of the SLATE ASM including the techniques used to track and classify detections that move through the field of view of the sensor providing the accurate tracking information to the SAPIENT system. SLATE's ability to locate targets precisely allows subtle boundary-crossing judgements, e.g. on which side of a chain-link fence a target is. SLATE's ability to track targets in 3D throughout its FoV enables behavior classification such as running and walking which can provide an indication of intent and help reduce false alarm rates.

  15. Rapid scanning autocorrelator for measurements of picosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Harde, H.; Burggraf, H.

    1981-08-01

    A rapid scanning autocorrelation interferometer for measurements of picosecond laser pulses is described which uses a rotating prism as scanning device in one arm of the interferometer to permit continuous display of autocorrelation traces at audio frequencies on an oscilloscope. Scan widths of more than 500 ps with high linearity can be achieved. Autocorrelation measurements of picosecond pulses from a synchronously pumped mode-locked dye laser are presented.

  16. Quality Analysis and Correction of Mobile Backpack Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Rönnholm, P.; Liang, X.; Kukko, A.; Jaakkola, A.; Hyyppä, J.

    2016-06-01

    Backpack laser scanning systems have emerged recently enabling fast data collection and flexibility to make measurements also in areas that cannot be reached with, for example, vehicle-based laser scanners. Backpack laser scanning systems have been developed both for indoor and outdoor use. We have developed a quality analysis process in which the quality of backpack laser scanning data is evaluated in the forest environment. The reference data was collected with an unmanned aerial vehicle (UAV) laser scanning system. The workflow included noise filtering, division of data into smaller patches, ground point extraction, ground data decimation, and ICP registration. As a result, we managed to observe the misalignments of backpack laser scanning data for 97 patches each including data from circa 10 seconds period of time. This evaluation revealed initial average misalignments of 0.227 m, 0.073 and -0.083 in the easting, northing and elevation directions, respectively. Furthermore, backpack data was corrected according to the ICP registration results. Our correction algorithm utilized the time-based linear transformation of backpack laser scanning point clouds. After the correction of data, the ICP registration was run again. This revealed remaining misalignments between the corrected backpack laser scanning data and the original UAV data. We found average misalignments of 0.084, 0.020 and -0.005 meters in the easting, northing and elevation directions, respectively.

  17. Laser-scanning techniques for rapid ballistics identification

    NASA Technical Reports Server (NTRS)

    Woodburgy, R. C.; Nakich, R. B.

    1974-01-01

    Two different laser-scanning methods may be utilized. In each case scanned cylindrical bullet surface is displayed ""unwrapped'' on oscilloscope screen. Bullets are compared by photographing each display and superimposing negatives of two images. With some modifications bullets can be scanned and compared by superimposing images on screen of dual-beam oscilloscope.

  18. Western Rainier Seismic Zone Airborne Laser Swath Mapping

    NASA Technical Reports Server (NTRS)

    Harding, David J.; Haugerud, Ralph A.; Johnson, Samuel Y.; Scott, Kevin M.; Weaver, Craig S.; Martinez, Diana M.; Zeigler, John C.; Latypov, Damir

    2003-01-01

    Airborne laser swath mapping (ALSM) of the Puget Lowland conducted by TerraPoint LLC for the Purget Sound Lidar Concortium (PSLC), has been successful in revealing Holocene fault scarps and lendsliders hidden beneath the dense, temperate rain forest cover and in quantifying shoreline terrace uplift. Expanding the PSLC efforts, NASA-USGS collaboration is now focusing on topographic mapping of seismogenic zones adjacent to volcanois in the western Cascades range in order to assess the presence of active faulting and tectonic deformation, better define the extend of lahars and understand their flow processes, and characterize landslide occurrence. Mapping of the western Rainier zone (WRZ) was conducted by TerraPoint in late 2002, after leaf fall and before snow accumulation. The WRZ is a NNW-trending, approx. 30 km-long zone of seismicity west of Mount Rainier National Park. The Puget Lowland ALSM methods were modified to accommodate challenges posed by the steep, high relief terrian. The laser data, acquired with a density of approx. 2 pulses /sq m, was filtered to identify returns from the ground from which a bare Earth digital elevation model (DEM) was produced with a grid size of 1.8 m. The RMS elevation accuracy of the DEM in flat, unvegetated areas is approx. 10cm based on consistency between overlapping flight swaths and comparisons to ground control points. The resulting DEM substantially improves upon Shuttle Radar Topography Mission and USGS photogrammetric mapping. For example, the DEM defines the size and spatial distribution of flood erratics left by the Electron lahar and of megaclasts within the Round Pass lahar, important for characterizing the lahar hydraulics. A previously unknown lateral levee on the Round Pass lahar is also revealed. In addition, to illustrating geomorfic feature within the WRZ, future plans for laser mapping of the Saint Helens and Darrington seismic zones will be described.

  19. Airborne Laser Bathymetry for Documentation of Submerged Archaeological Sites in Shallow Water

    NASA Astrophysics Data System (ADS)

    Doneus, M.; Miholjek, I.; Mandlburger, G.; Doneus, N.; Verhoeven, G.; Briese, Ch.; Pregesbauer, M.

    2015-04-01

    Knowledge of underwater topography is essential to the understanding of the organisation and distribution of archaeological sites along and in water bodies. Special attention has to be paid to intertidal and inshore zones where, due to sea-level rise, coastlines have changed and many former coastal sites are now submerged in shallow water. Mapping the detailed inshore topography is therefore important to reconstruct former coastlines, identify sunken archaeological structures and locate potential former harbour sites. However, until recently archaeology has lacked suitable methods to provide the required topographical data of shallow underwater bodies. Our research shows that airborne topo-bathymetric laser scanner systems are able to measure surfaces above and below the water table over large areas in high detail using very short and narrow green laser pulses, even revealing sunken archaeological structures in shallow water. Using an airborne laser scanner operating at a wavelength in the green visible spectrum (532 nm) two case study areas in different environmental settings (Kolone, Croatia, with clear sea water; Lake Keutschach, Austria, with turbid water) were scanned. In both cases, a digital model of the underwater topography with a planimetric resolution of a few decimeters was measured. While in the clear waters of Kolone penetration depth was up to 11 meters, turbid Lake Keutschach allowed only to document the upper 1.6 meters of its underwater topography. Our results demonstrate the potential of this technique to map submerged archaeological structures over large areas in high detail providing the possibility for systematic, large scale archaeological investigation of this environment.

  20. Apparatus for controlling the scan width of a scanning laser beam

    DOEpatents

    Johnson, Gary W.

    1996-01-01

    Swept-wavelength lasers are often used in absorption spectroscopy applications. In experiments where high accuracy is required, it is desirable to continuously monitor and control the range of wavelengths scanned (the scan width). A system has been demonstrated whereby the scan width of a swept ring-dye laser, or semiconductor diode laser, can be measured and controlled in real-time with a resolution better than 0.1%. Scan linearity, or conformity to a nonlinear scan waveform, can be measured and controlled. The system of the invention consists of a Fabry-Perot interferometer, three CAMAC interface modules, and a microcomputer running a simple analysis and proportional-integral control algorithm. With additional modules, multiple lasers can be simultaneously controlled. The invention also includes an embodiment implemented on an ordinary PC with a multifunction plug-in board.

  1. Apparatus for controlling the scan width of a scanning laser beam

    DOEpatents

    Johnson, G.W.

    1996-10-22

    Swept-wavelength lasers are often used in absorption spectroscopy applications. In experiments where high accuracy is required, it is desirable to continuously monitor and control the range of wavelengths scanned (the scan width). A system has been demonstrated whereby the scan width of a swept ring-dye laser, or semiconductor diode laser, can be measured and controlled in real-time with a resolution better than 0.1%. Scan linearity, or conformity to a nonlinear scan waveform, can be measured and controlled. The system of the invention consists of a Fabry-Perot interferometer, three CAMAC interface modules, and a microcomputer running a simple analysis and proportional-integral control algorithm. With additional modules, multiple lasers can be simultaneously controlled. The invention also includes an embodiment implemented on an ordinary PC with a multifunction plug-in board. 8 figs.

  2. Confocal scanning beam laser microscope/macroscope: applications in fluorescence

    NASA Astrophysics Data System (ADS)

    Dixon, Arthur E.; Damaskinos, Savvas; Ribes, Alfonso

    1996-03-01

    A new confocal scanning beam laser microscope/macroscope is described that combines the rapid scan of a scanning beam laser microscope with the large specimen capability of a scanning stage microscope. This instrument combines an infinity-corrected confocal scanning laser microscope with a scanning laser macroscope that uses a telecentric f*(Theta) laser scan lens to produce a confocal imaging system with a resolution of 0.25 microns at a field of view of 25 microns and 5 microns at a field of view of 75,000 microns. The frame rate is 5 seconds per frame for a 512 by 512 pixel image, and 25 seconds for a 2048 by 2048 pixel image. Applications in fluorescence are discussed that focus on two important advantages of the instrument over a confocal scanning laser microscope: an extremely wide range of magnification, and the ability to image very large specimens. Examples are presented of fluorescence and reflected-light images of high quality printing, fluorescence images of latent fingerprints, packaging foam, and confocal autofluorescence images of a cricket.

  3. Remote Sensing of Wind Fields and Aerosol Distribution with Airborne Scanning Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry; Cutten, Dean R.; Johnson, Steven C.; Jazembski, Maurice; Arnold, James E. (Technical Monitor)

    2001-01-01

    The coherent Doppler laser radar (lidar), when operated from an airborne platform, is a unique tool for the study of atmospheric and surface processes and features. This is especially true for scientific objectives requiring measurements in optically-clear air, where other remote sensing technologies such as Doppler radar are typically at a disadvantage. The atmospheric lidar remote sensing groups of several US institutions, led by Marshall Space Flight Center, have developed an airborne coherent Doppler lidar capable of mapping the wind field and aerosol structure in three dimensions. The instrument consists of an eye-safe approx. 1 Joule/pulse lidar transceiver, telescope, scanner, inertial measurement unit, and flight computer system to orchestrate all subsystem functions and tasks. The scanner is capable of directing the expanded lidar beam in a variety of ways, in order to extract vertically-resolved wind fields. Horizontal resolution is approx. 1 km; vertical resolution is even finer. Winds are obtained by measuring backscattered, Doppler-shifted laser radiation from naturally-occurring aerosol particles (of order 1 micron diameter). Measurement coverage depends on aerosol spatial distribution and composition. Velocity accuracy has been verified to be approx. 1 meter per second. A variety of applications have been demonstrated during the three flight campaigns conducted during 1995-1998. Examples will be shown during the presentation. In 1995, boundary layer winds over the ocean were mapped with unprecedented resolution. In 1996, unique measurements were made of. flow over the complex terrain of the Aleutian Islands; interaction of the marine boundary layer jet with the California coastal mountain range; a weak dry line in Texas - New Mexico; the angular dependence of sea surface scattering; and in-flight radiometric calibration using the surface of White Sands National Monument. In 1998, the first measurements of eyewall and boundary layer winds within a

  4. A semi-automatic 3D laser scan system design

    NASA Astrophysics Data System (ADS)

    Xiong, Hanwei; Pan, Ming; Zhang, Xiangwei

    2009-11-01

    Digital 3D models are now used everywhere, from traditional fields of industrial design, artistic design, to heritage conservation. Although laser scan is very useful to get densely samples of the objects, nowadays, such an instrument is expensive and always need to be connected to a computer with stable power supply, which prevent it from usage for fieldworks. In this paper, a new semi-automatic 3D laser scan method is proposed using two line laser sources. The planes projected from the laser sources are orthogonal, one of which is fixed relative to the camera, and the other can be rotated along a settled axis. Before scanning, the system must be calibrated, from which the parameters of the camera, the position of the fixed laser plane and the settled axis are introduced. In scanning process, the fixed laser plane and the camera form a conventional structured light system, and the 3d positions of the intersection curves of the fixed laser plane with the object can be computed. The other laser plane is rotated manually or mechanically, and its position can be determined from the cross point intersecting with the fixed laser plane on the object, so the coordinates of sweeping points can be obtained. The new system can be used without a computer (The data can be processed later), which make it suitable for fieldworks. A scanning case is given in the end.

  5. Three-dimensional scanning confocal laser microscope

    DOEpatents

    Anderson, R. Rox; Webb, Robert H.; Rajadhyaksha, Milind

    1999-01-01

    A confocal microscope for generating an image of a sample includes a first scanning element for scanning a light beam along a first axis, and a second scanning element for scanning the light beam at a predetermined amplitude along a second axis perpendicular to the first axis. A third scanning element scans the light beam at a predetermined amplitude along a third axis perpendicular to an imaging plane defined by the first and second axes. The second and third scanning element are synchronized to scan at the same frequency. The second and third predetermined amplitudes are percentages of their maximum amplitudes. A selector determines the second and third predetermined amplitudes such that the sum of the percentages is equal to one-hundred percent.

  6. Extraction of tidal channel networks from airborne scanning laser altimetry

    NASA Astrophysics Data System (ADS)

    Mason, David C.; Scott, Tania R.; Wang, Hai-Jing

    Tidal channel networks are important features of the inter-tidal zone, and play a key role in tidal propagation and in the evolution of salt marshes and tidal flats. The study of their morphology is currently an active area of research, and a number of theories related to networks have been developed which require validation using dense and extensive observations of network forms and cross-sections. The conventional method of measuring networks is cumbersome and subjective, involving manual digitisation of aerial photographs in conjunction with field measurement of channel depths and widths for selected parts of the network. This paper describes a semi-automatic technique developed to extract networks from high-resolution LiDAR data of the inter-tidal zone. A multi-level knowledge-based approach has been implemented, whereby low-level algorithms first extract channel fragments based mainly on image properties then a high-level processing stage improves the network using domain knowledge. The approach adopted at low level uses multi-scale edge detection to detect channel edges, then associates adjacent anti-parallel edges together to form channels. The higher level processing includes a channel repair mechanism. The algorithm may be extended to extract networks from aerial photographs as well as LiDAR data. Its performance is illustrated using LiDAR data of two study sites, the River Ems, Germany and the Venice Lagoon. For the River Ems data, the error of omission for the automatic channel extractor is 26%, partly because numerous small channels are lost because they fall below the edge threshold, though these are less than 10 cm deep and unlikely to be hydraulically significant. The error of commission is lower, at 11%. For the Venice Lagoon data, the error of omission is 14%, but the error of commission is 42%, due partly to the difficulty of interpreting channels in these natural scenes. As a benchmark, previous work has shown that this type of algorithm specifically designed for extracting tidal networks from LiDAR data is able to achieve substantially improved results compared with those obtained using standard algorithms for drainage network extraction from Digital Terrain Models.

  7. Design of an Airborne L-Band Cross-Track Scanning Scatterometer

    NASA Technical Reports Server (NTRS)

    Hilliard, Lawrence M. (Technical Monitor)

    2002-01-01

    In this report, we describe the design of an airborne L-band cross-track scanning scatterometer suitable for airborne operation aboard the NASA P-3 aircraft. The scatterometer is being designed for joint operation with existing L-band radiometers developed by NASA for soil moisture and ocean salinity remote sensing. In addition, design tradeoffs for a space-based radar system have been considered, with particular attention given to antenna architectures suitable for sharing the antenna between the radar and radiometer. During this study, we investigated a number of imaging techniques, including the use of real and synthetic aperture processing in both the along track and cross-track dimensions. The architecture selected will permit a variety of beamforming algorithms to be implemented, although real aperture processing, with hardware beamforming, provides better sidelobe suppression than synthetic array processing and superior signal-to-noise performance. In our discussions with the staff of NASA GSFC, we arrived at an architecture that employs complete transmit/receive modules for each subarray. Amplitude and phase control at each of the transmit modules will allow a low-sidelobe transmit pattern to be generated over scan angles of +/- 50 degrees. Each receiver module will include all electronics necessary to downconvert the received signal to an IF offset of 30 MHz where it will be digitized for further processing.

  8. Airborne Laser Swath Mapping Imagery for GeoEarthScope

    NASA Astrophysics Data System (ADS)

    Phillips, D. A.; Jackson, M. E.; Meertens, C. M.

    2007-12-01

    UNAVCO is acquiring Airborne Laser Swath Mapping (a.k.a. airborne LiDAR) imagery for GeoEarthScope, a component of the EarthScope Facility project funded by the National Science Foundation. Guided by the UNAVCO GeoEarthScope LiDAR Working Group, these projects are designed and conducted based on community recommendations with respect to target identification and data collection practices so as to provide the EarthScope community with a rich, high quality data set capable of supporting a wide range of interests and applications. Anticipated applications range from operational, such as assisting with EarthScope instrument siting, to pioneering research in many fields of study including tectonophysics, geomorphology and paleoseismology to name a few. As of September 2007, two GeoEarthScope ALSM projects have been completed: 1) a 1500+ sq km project in northern California that focused on the San Andreas fault and other active structures, and 2) a ~450 sq km project in Death Valley that focused on the Death Valley-Fish Lake Valley fault system. The northern California data were collected during an extensive, highly collaborative field campaign in Spring 2007. ALSM data were collected by the National Center for Airborne Laser Mapping (NCALM) with a new generation Optech Gemini scanner at high pulse rate frequencies, and high rate GPS data were collected by regional networks such as PBO and by campaign systems deployed by a team of personnel from Ohio State University, UNAVCO, the U.S. Geological Survey and student volunteers from local universities. Also for this project, primary GeoEarthScope targets were expanded to include additional targets such as the Hayward fault through supplemental funding contributions from the USGS, the City of Berkeley, and the San Francisco Public Utilities Commission. The northern California dataset complements the previously acquired "B4" ALSM dataset in southern California by overlapping B4 coverage along the creeping section of the San

  9. Damage visualization using synchronized noncontact laser ultrasonic scanning

    NASA Astrophysics Data System (ADS)

    Liu, Peipei; Sunarsa, Timotius Yonathan; Sohn, Hoon

    2016-04-01

    This paper presents a damage visualization technique using a fully noncontact laser ultrasonic measurement system and a synchronized scanning strategy. The noncontact laser ultrasonic measurement system is composed of a Q-switched Nd:YAG laser for ultrasonic wave generation and a laser Doppler vibrometer (LDV) for ultrasonic wave detection. The laser beams for ultrasonic wave generation and detection are shot on the target structure with a constant and tiny distance, and these two laser beams are synchronously moved over the scanning area. Compared with conventional laser scanning strategies, the ultrasonic responses detected through the synchronized scanning strategy owns a much higher and more stable signal to noise ratio and the scanning time can be significantly reduced with less time averaging. By spatial comparison in the scanning area, damage can be detected and visualized without relying on baseline data obtained from the pristine condition of the target structure. In this paper, the developed technique is validated by visualization hidden corrosion in a steel straight pipe and a steel elbow pipe.

  10. Airborne laser ranging system for monitoring regional crustal deformation

    NASA Technical Reports Server (NTRS)

    Degnan, J. J.

    1981-01-01

    Alternate approaches for making the atmospheric correction without benefit of a ground-based meteorological network are discussed. These include (1) a two-color channel that determines the atmospheric correction by measuring the time delay induced by dispersion between pulses at two optical frequencies; (2) single-color range measurements supported by an onboard temperature sounder, pressure altimeter readings, and surface measurements by a few existing meteorological facilities; and (3) inclusion of the quadratic polynomial coefficients as variables to be solved for along with target coordinates in the reduction of the single-color range data. It is anticipated that the initial Airborne Laser Ranging System (ALRS) experiments will be carried out in Southern California in a region bounded by Santa Barbara on the norht and the Mexican border on the south. The target area will be bounded by the Pacific Ocean to the west and will extend eastward for approximately 400 km. The unique ability of the ALRS to provide a geodetic 'snapshot' of such a large area will make it a valuable geophysical tool.

  11. Laser safety in design of near-infrared scanning LIDARs

    NASA Astrophysics Data System (ADS)

    Zhu, X.; Elgin, D.

    2015-05-01

    3D LIDARs (Light Detection and Ranging) with 1.5μm nanosecond pulse lasers have been increasingly used in different applications. The main reason for their popularity is that these LIDARs have high performance while at the same time can be made eye-safe. Because the laser hazard effect on eyes or skin at this wavelength region (<1.4μm) is mainly from the thermal effect accumulated from many individual pulses over a period of seconds, scanning can effectively reduce the laser beam hazard effect from the LIDARs. Neptec LIDARs have been used in docking to the International Space Station, military helicopter landing and industrial mining applications. We have incorporated the laser safety requirements in the LIDAR design and conducted laser safety analysis for different operational scenarios. While 1.5μm is normally said to be the eye-safe wavelength, in reality a high performance 3D LIDAR needs high pulse energy, small beam size and high pulse repetition frequency (PRF) to achieve long range, high resolution and high density images. The resulting radiant exposure of its stationary beam could be many times higher than the limit for a Class 1 laser device. Without carefully choosing laser and scanning parameters, including field-of-view, scan speed and pattern, a scanning LIDAR can't be eye- or skin-safe based only on its wavelength. This paper discusses the laser safety considerations in the design of eye-safe scanning LIDARs, including laser pulse energy, PRF, beam size and scanning parameters in two basic designs of scanning mechanisms, i.e. galvanometer based scanner and Risley prism based scanner. The laser safety is discussed in terms of device classification, nominal ocular hazard distance (NOHD) and safety glasses optical density (OD).

  12. Comparison of point clouds derived from aerial image matching with data from airborne laser scanning. (Polish Title: Porównanie wóaściwości chmury punktów wygenerowanej metodą dopasowania obrazów zdjęć lotniczych z danymi z lotniczego skanowania)

    NASA Astrophysics Data System (ADS)

    Dominik, W.

    2014-12-01

    The aim of this study was to investigate the properties of point clouds derived from aerial image matching and to compare them with point clouds from airborne laser scanning. A set of aerial images acquired in years 2010-2013 over the city of Elblag were used for the analysis. Images were acquired with the use of three digital cameras: DMC II 230, DMC I and DigiCAM60 with a GSD varying from 4.5 cm to 15 cm. Eight sets of images that were used in the study were acquired at different stages of the growing season - from March to December. Two LiDAR point clouds were used for the comparison - one with a density of 1.3 p/m2 and a second with a density of 10 p/m2. Based on the input images point clouds were created with the use of the semi-global matching method. The properties of the obtained point clouds were analyzed in three ways: - by the comparison of the vertical accuracy of point clouds with reference to a terrain profile surveyed on bare ground with GPS-RTK method - by visual assessment of point cloud profiles generated both from SGM and LiDAR point clouds - by visual assessment of a digital surface model generated from a SGM point cloud with reference to a digital surface model generated from a LiDAR point cloud. The conducted studies allowed a number of observations about the quality of SGM point clouds to be formulated with respect to different factors. The main factors having influence on the quality of SGM point clouds are GSD and base/height ratio. The essential problem related to SGM point clouds are areas covered with vegetation where SGM point clouds are visibly worse in terms of both accuracy and the representation of terrain surface. It is difficult to expect that in these areas SGM point clouds could replace LiDAR point clouds. This leads to a general conclusion that SGM point clouds are less reliable, more unpredictable and are dependent on more factors than LiDAR point clouds. Nevertheless, SGM point clouds generated with appropriate parameters can

  13. CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE OVARIES

    EPA Science Inventory

    Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle...

  14. Software for visualization, analysis, and manipulation of laser scan images

    NASA Astrophysics Data System (ADS)

    Burnsides, Dennis B.

    1997-03-01

    The recent introduction of laser surface scanning to scientific applications presents a challenge to computer scientists and engineers. Full utilization of this two- dimensional (2-D) and three-dimensional (3-D) data requires advances in techniques and methods for data processing and visualization. This paper explores the development of software to support the visualization, analysis and manipulation of laser scan images. Specific examples presented are from on-going efforts at the Air Force Computerized Anthropometric Research and Design (CARD) Laboratory.

  15. Comparison of three-dimensional retinal imaging methods: the method of scanning laser triangulation.

    PubMed

    Milbocker, M T; Reznichenko, Y M

    1991-10-01

    Three methods of three-dimensional imaging of the vitreous and the fundus of the human eye are compared. Equations are derived for the theoretical depth resolution of stereophotogrammetry, scanning laser tomography, and scanning laser triangulation. Scanning laser triangulation provides superior depth resolution without requiring axial scanning. A description of a prototype scanning laser triangulator is given.

  16. Multiparameter Correction Intensity of Terrestrial Laser Scanning Data as AN Input for Rock Surface Modelling

    NASA Astrophysics Data System (ADS)

    Paleček, V.; Kubíček, P.

    2016-06-01

    A large increase in the creation of 3D models of objects all around us can be observed in the last few years; thanks to the help of the rapid development of new advanced technologies for spatial data collection and robust software tools. A new commercially available airborne laser scanning data in Czech Republic, provided in the form of the Digital terrain model of the fifth generation as irregularly spaced points, enable locating the majority of rock formations. However, the positional and height accuracy of this type of landforms can reach huge errors in some cases. Therefore, it is necessary to start mapping using terrestrial laser scanning with the possibility of adding a point cloud data derived from ground or aerial photogrammetry. Intensity correction and noise removal is usually based on the distance between measured objects and the laser scanner, the incidence angle of the beam or on the radiometric and topographic characteristics of measured objects. This contribution represents the major undesirable effects that affect the quality of acquisition and processing of laser scanning data. Likewise there is introduced solutions to some of these problems.

  17. Stereo vision based hand-held laser scanning system design

    NASA Astrophysics Data System (ADS)

    Xiong, Hanwei; Xu, Jun; Wang, Jinming

    2011-11-01

    Although 3D scanning system is used more and more broadly in many fields, such computer animate, computer aided design, digital museums, and so on, a convenient scanning device is expansive for most people to afford. In another hand, imaging devices are becoming cheaper, a stereo vision system with two video cameras cost little. In this paper, a hand held laser scanning system is design based on stereo vision principle. The two video cameras are fixed tighter, and are all calibrated in advance. The scanned object attached with some coded markers is in front of the stereo system, and can be changed its position and direction freely upon the need of scanning. When scanning, the operator swept a line laser source, and projected it on the object. At the same time, the stereo vision system captured the projected lines, and reconstructed their 3D shapes. The code markers are used to translate the coordinate system between scanned points under different view. Two methods are used to get more accurate results. One is to use NURBS curves to interpolate the sections of the laser lines to obtain accurate central points, and a thin plate spline is used to approximate the central points, and so, an exact laser central line is got, which guards an accurate correspondence between tow cameras. Another way is to incorporate the constraint of laser swept plane on the reconstructed 3D curves by a PCA (Principle Component Analysis) algorithm, and more accurate results are obtained. Some examples are given to verify the system.

  18. CONFOCAL LASER SCANNING MICROSCOPY OF RAT FOLLICLE DEVELOPMENT

    EPA Science Inventory

    This study used confocal laser scanning microscopy (CLSM) to study follicular development in millimeter pieces of rat ovary. To use this technology, it is essential to stain the tissue before laser excitation with the confocal microscope. Various fluorescent stains (Yo-Pro, Bo-Pr...

  19. Automated pressure scanning of tunable dye lasers

    NASA Astrophysics Data System (ADS)

    Gottscho, R. A.

    1985-04-01

    A method for the remote control of tunable laser frequency tuning is proposed in the framework of real-time monitoring of the chemistry and physics of plasma, combustion, and chemical vapor deposition reactions. The technique presented involves indirect frequency tuning and stabilization by direct control of the laser cavity pressure. The long-term drift in power, resulting from the grating and etalon misalignment is suggested to be correctable by using a second feedback circuit which would optimize laser power by finely tuning the etalon or grating. Experimental results obtained with a dye laser of Hansch type are included; a maximum variation in LIF signal of + or - 7 percent, which corresponds to a frequency drift of + or - 0.005/cm, over a 30-min interval was achieved. A block diagram of the feedback loop and the LIF apparatus are included.

  20. Airborne Laser Swath Mapping: Improved Penetration of Dense Vegetation Opens New Applications

    NASA Astrophysics Data System (ADS)

    Carter, W. E.; Shrestha, R. L.; Slatton, K. C.

    2009-12-01

    Historically, mapping structures and terrain obscured by dense forests has been problematical, because shadows limit or prevent the use of airborne photogrammetric techniques, and ground surveying techniques are slow, labor intensive, and too costly for many applications. Airborne laser swath mapping (ALSM) units with pulse rates of a few thousand to a few tens of thousands of pulses per second typically resulted in 1 or 2 points per square meter of terrain, which worked reasonably well in sparse to moderately forested areas. For example, data collected with a 30 kHz laser, provided sufficient returns from the ground in areas covered with redwood, mixed hardwoods, and conifer forests, to create 1 to 2 meter resolution bare earth digital elevation models (DEM). These DEMs were useful in studies of forest covered landslides, terraces, and fault lines. However, in dense semi-tropical areas of Florida, with primary and secondary canopies that include dense brush such as palmetto, the DEMs were significantly degraded, and in many areas it was not possible to derive bare earth DEMs that were reliable in height to better than 0.5 to 1.0 meter. In 2007 the UF purchased a second generation Optech ALSM unit that has decimeter accuracy ranging with pulse rates of 100 to 125 kHz. Flying at 600 meters AGL, 60 meters per second, and using a scan angle of ± 20 degrees and scan rate of 40 Hz, results in about 5 laser pulses per square meter within a single swath. In April 2009 a UF team collected ALSM observations covering approximately 2000 acres at Caracol, Belize, to support archaeological studies of the ancient (650 to 900AD) Mayan city, which is largely covered with dense jungle. By overlapping adjacent swaths by 50%, and flying the project area twice with orthogonal flight lines, an accumulated data set containing approximately 20 pulses per square meter, with a distribution of incident angles was realized. The Caracol area has been under study for 25 years and traditional

  1. An Airborne Scanning LiDAR System for Ocean and Coastal Applications

    NASA Astrophysics Data System (ADS)

    Reineman, B. D.; Lenain, L.; Castel, D.; Melville, W. K.

    2008-12-01

    We have developed an airborne scanning LiDAR (Light Detection And Ranging) system and demonstrated its functionality for terrestrial and oceanographic measurements. Differential GPS (DGPS) and an Inertial Navigation System (INS) are synchronized with the LiDAR, providing end result vertical rms errors of approximately 6~cm. Flying 170~m above the surface, we achieve a point density of ~ 0.7 m-2 and a swath width of 90 to 120~m over ocean and 200~m over land. Georeferencing algorithms were developed in-house and earth-referenced data are available several hours after acquisition. Surveys from the system are compared with ground DGPS surveys and existing airborne surveys of fixed targets. Twelve research flights in a Piper Twin Comanche from August 2007 to July 2008 have provided topography of the Southern California coastline and sea surface wave fields in the nearshore ocean environment. Two of the flights also documented the results of the October 2007 landslide on Mt.~Soledad in La Jolla, California. Eight research flights aboard a Cessna Caravan surveyed the topography, lagoon, reef, and surrounding seas of Lady Elliot Island (LEI) in Australia's Great Barrier Reef in April 2008. We describe applications for the system, including coastal topographic surveys, wave measurements, reef research, and ship wake studies.

  2. Derivation of Cumulus Cloud Dimensions and Shape from the Airborne Measurements by the Research Scanning Polarimeter

    NASA Technical Reports Server (NTRS)

    Alexandrov, Mikhail D.; Cairns, Brian; Emde, Claudia; Ackerman, Andrew S.; Ottaviani, Matteo; Wasilewski, Andrzej P.

    2016-01-01

    The Research Scanning Polarimeter (RSP) is an airborne instrument, whose measurements have been extensively used for retrievals of microphysical properties of clouds. In this study we show that for cumulus clouds the information content of the RSP data can be extended by adding the macroscopic parameters of the cloud, such as its geometric shape, dimensions, and height above the ground. This extension is possible by virtue of the high angular resolution and high frequency of the RSP measurements, which allow for geometric constraint of the cloud's 2D cross section between a number of tangent lines of view. The retrieval method is tested on realistic 3D radiative transfer simulations and applied to actual RSP data.

  3. Laser-scanning Doppler photoacoustic microscopy based on temporal correlation

    NASA Astrophysics Data System (ADS)

    Song, Wei; Liu, Wenzhong; Zhang, Hao F.

    2013-05-01

    We present a methodology to measure absolute flow velocity using laser-scanning photoacoustic microscopy. To obtain the Doppler angle, the angle between ultrasonic detection axis and flow direction, we extracted the distances between the transducer and three adjacent scanning points along the flow and repeatedly applied the law of cosines. To measure flow velocity along the ultrasonic detection axis, we calculated the time shift between two consecutive photoacoustic waves at the same scanning point, then converted the time shift to velocity according to the sound velocity and time interval between two laser illuminations. We verified our method by imaging flow phantoms.

  4. Effects of scanning orientation on outlier formation in 3D laser scanning of reflective surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Yutao; Feng, Hsi-Yung

    2016-06-01

    Inspecting objects with reflective surfaces using 3D laser scanning is a demanded but challenging part inspection task due to undesirable specular reflections, which produce extensive outliers in the scanned point cloud. These outliers need to be removed in order to alleviate subsequent data processing issues. Many existing automatic outlier removal methods do not detect outliers according to the outlier formation properties. As a result, these methods only offer limited capabilities in removing extensive and complex outliers from scanning objects with reflective surfaces. This paper reports an empirical study which experimentally investigates the outlier formation characteristics in relation to the scanning orientation of the laser probe. The objective is to characterize the scanning orientation effects on outlier formation in order to facilitate the development of an effective outlier detection and removal method. Such an experimental investigation was hardly done before. It has been found in this work that scanning orientation can directly affect outlier extensity and occurrence in 3D laser scanning. A general guidance on proper scan path planning can then be provided with an aim to reduce the occurrence of outliers. Further, the observed dependency of outlier formation on scanning orientation can be exploited to facilitate effective and automatic outlier detection and removal.

  5. Phase relation recovery for scanning laser Doppler vibrometry

    NASA Astrophysics Data System (ADS)

    Alveringh, D.; Sanders, R. G. P.; Wiegerink, R. J.; Lötters, J. C.

    2017-02-01

    Laser Doppler vibrometers are able to measure the velocity of a single point compared to a reference point by analyzing the Doppler shift of the laser beams. In many commercially available laser Doppler vibrometers, the laser point can be scanned to obtain an out-of-plane velocity profile of a surface. It is essential that the phase information of the velocities between points is measured as well to be able to fully reproduce the velocity profile of the surface. If this cannot be done by triggering on the actuation signal, the proposed two stage method can be used. This method measures the surface in two stages: one scan with the reference beam at a fixed point and one scan with the reference beam on a moving point. The algorithm in this article calculates the phase and reconstructs the velocity of each point. This is experimentally verified on three different micro structures. The postprocessing algorithm is not intensive in computing power.

  6. 3D Laser Scanning in Technology Education.

    ERIC Educational Resources Information Center

    Flowers, Jim

    2000-01-01

    A three-dimensional laser scanner can be used as a tool for design and problem solving in technology education. A hands-on experience can enhance learning by captivating students' interest and empowering them with creative tools. (Author/JOW)

  7. High-energy, efficient, 30-Hz ultraviolet laser sources for airborne ozone-lidar systems.

    PubMed

    Elsayed, Khaled A; Chen, Songsheng; Petway, Larry B; Meadows, Byron L; Marsh, Waverly D; Edwards, William C; Barnes, James C; DeYoung, Russell J

    2002-05-20

    Two compact, high-pulse-energy, injection-seeded, 30-Hz frequency-doubled Nd:YAG-laser-pumped Ti: sapphire lasers were developed and operated at infrared wavelengths of 867 and 900 nm. Beams with laser pulse energy >30 mJ at ultraviolet wavelengths of 289 and 300 nm were generated through a tripling of the frequencies of these Ti:sapphire lasers. This work is directed at the replacement of dye lasers for use in an airborne ozone differential absorption lidar system. The ultraviolet pulse energy at 289 and 300 nm had 27% and 31% absolute optical energy conversion efficiencies from input pulse energies at 867 and 900 nm, respectively.

  8. A Laser Sheet Self-Calibration Method for Scanning PIV

    NASA Astrophysics Data System (ADS)

    Knutsen, Anna N.; Dawson, James R.; Lawson, John M.; Worth, Nicholas A.

    2016-11-01

    A laser sheet self-calibration method for scanning PIV has been developed to replace the current laser sheet calibration, which is complex, time consuming and very sensitive to misalignment of the optics or cameras during experiments. The new calibration method is simpler, faster and crucially more robust. The concept behind the method is to traverse a laser sheet through the measurement volume, take a series of images from two different views, and calculate the global 3D particle locations. This information is used to find the real space coordinates of the measurement volume and the orientation and width of the laser sheets. The spatial location of the particles is found by object matching and triangulation. The light intensity in the laser sheet has an approximately Gaussian shape, and the illumination of one particle which will be illuminated multiple times during the scan will thus vary as the sheet is scanned across the measurement volume. The thickness of the laser sheet is calculated by identifying the variation of illumination of the particles during a scan and fitting this to a Gaussian shaped curve, while the orientation is found using a least square fit. The accuracy of the new method will be presented with respect to both synthetic and experimental data.

  9. Repeat scanning technology for laser ultrasonic propagation imaging

    NASA Astrophysics Data System (ADS)

    Lee, Jung-Ryul; Yenn Chong, See; Sunuwar, Nitam; Park, Chan Yik

    2013-08-01

    Laser ultrasonic scanning in combination with contact or non-contact sensors provides new paradigms in structural health management (SHM) and non-destructive in-process quality control (IPQC) for large composite structures. Wave propagation imaging technology based on laser ultrasonic scanning and fixed-point sensing shows remarkable advantages, such as minimal need for embedded sensors in SHM, minimum invasive defect visualization in IPQC and general capabilities of curved and complex target inspection, and temporal reference-free inspection. However, as with other SHM methods and non-destructive evaluation based on ultrasound, the signal-to-noise ratio (SNR) is a prevalent issue in real structural applications, especially with non-contact thin-composite sensing or with thick and heterogeneous composites. This study proposes a high-speed repeat scanning technique for laser ultrasonic propagation imaging (UPI) technology, which is realized with the scanning speed of 1 kHz of a Q-switched continuous wave laser, and precise control of the laser beam pulses for identical point scanning. As a result, the technique enables the achievement of significant improvement in the SNR to inspect real-world composite structures. The proposed technique provides enhanced results for impact damage detection in a 2 mm thick wing box made of carbon-fiber-reinforced plastic, despite the low sensitivity of non-contact laser ultrasonic sensing. A field-applicable pure laser UPI system has been developed using a laser Doppler vibrometer as the non-contact ultrasonic sensor. The proposed technique enables the visualization of the disbond defect in a 15 mm thick wind blade specimen made of glass-fiber-reinforced plastic, despite the high dissipation of ultrasound in the thick composite.

  10. Four-laser airborne infrared spectrometer for atmospheric trace gas measurements.

    PubMed

    Roths, J; Zenker, T; Parchatka, U; Wienhold, F G; Harris, G W

    1996-12-20

    We describe the four-laser airborne infrared (FLAIR) instrument, a tunable diode laser absorption spectrometer designed for simultaneous high-sensitivity in situ measurements of four atmospheric trace gases in the troposphere. The FLAIR spectrometer was employed during the large-scale airborne research campaign on tropospheric ozone (TROPOZ II) in 1991 and was used to measure CO, H(2) O(2), HCHO, and NO(2) in the free troposphere where detection limits below 100 parts in 10(12) by volume were achieved.

  11. Laser hazard analysis for airborne AURA (Big Sky variant) Proteus platform.

    SciTech Connect

    Augustoni, Arnold L.

    2004-02-01

    A laser safety and hazard analysis was performed for the airborne AURA (Big Sky Laser Technology) lidar system based on the 2000 version of the American National Standard Institute's (ANSI) Standard Z136.1, for the Safe Use of Lasers and the 2000 version of the ANSI Standard Z136.6, for the Safe Use of Lasers Outdoors. The AURA lidar system is installed in the instrument pod of a Proteus airframe and is used to perform laser interaction experiments and tests at various national test sites. The targets are located at various distances or ranges from the airborne platform. In order to protect personnel, who may be in the target area and may be subjected to exposures, it was necessary to determine the Maximum Permissible Exposure (MPE) for each laser wavelength, calculate the Nominal Ocular Hazard Distance (NOHD), and determine the maximum 'eye-safe' dwell times for various operational altitudes and conditions. It was also necessary to calculate the appropriate minimum Optical Density (ODmin) of the laser safety eyewear used by authorized personnel who may receive hazardous exposures during ground base operations of the airborne AURA laser system (system alignment and calibration).

  12. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas; Fowlkes, Jason Davidson; Rack, Prof. Philip; Moore, Tom; Magel, Greg; Hartfield, Cheryl

    2012-01-01

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {micro}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  13. In situ laser processing in a scanning electron microscope

    SciTech Connect

    Roberts, Nicholas A.; Magel, Gregory A.; Hartfield, Cheryl D.; Moore, Thomas M.; Fowlkes, Jason D.; Rack, Philip D.

    2012-07-15

    Laser delivery probes using multimode fiber optic delivery and bulk focusing optics have been constructed and used for performing materials processing experiments within scanning electron microscope/focused ion beam instruments. Controlling the current driving a 915-nm semiconductor diode laser module enables continuous or pulsed operation down to sub-microsecond durations, and with spot sizes on the order of 50 {mu}m diameter, achieving irradiances at a sample surface exceeding 1 MW/cm{sup 2}. Localized laser heating has been used to demonstrate laser chemical vapor deposition of Pt, surface melting of silicon, enhanced purity, and resistivity via laser annealing of Au deposits formed by electron beam induced deposition, and in situ secondary electron imaging of laser induced dewetting of Au metal films on SiO{sub x}.

  14. Capturing and modelling high-complex alluvial topography with UAS-borne laser scanning

    NASA Astrophysics Data System (ADS)

    Mandlburger, Gottfried; Wieser, Martin; Pfennigbauer, Martin

    2015-04-01

    Due to fluvial activity alluvial forests are zones of highest complexity and relief energy. Alluvial forests are dominated by new and pristine channels in consequence of current and historic flood events. Apart from topographic features, the vegetation structure is typically very complex featuring, both, dense under story as well as high trees. Furthermore, deadwood and debris carried from upstream during periods of high discharge within the river channel are deposited in these areas. Therefore, precise modelling of the micro relief of alluvial forests using standard tools like Airborne Laser Scanning (ALS) is hardly feasible. Terrestrial Laser Scanning (TLS), in turn, is very time consuming for capturing larger areas as many scan positions are necessary for obtaining complete coverage due to view occlusions in the forest. In the recent past, the technological development of Unmanned Arial Systems (UAS) has reached a level that light-weight survey-grade laser scanners can be operated from these platforms. For capturing alluvial topography this could bridge the gap between ALS and TLS in terms of providing a very detailed description of the topography and the vegetation structure due to the achievable very high point density of >100 points per m2. In our contribution we demonstrate the feasibility to apply UAS-borne laser scanning for capturing and modelling the complex topography of the study area Neubacher Au, an alluvial forest at the pre-alpine River Pielach (Lower Austria). The area was captured with Riegl's VUX-1 compact time-of-flight laser scanner mounted on a RiCopter (X-8 array octocopter). The scanner features an effective scan rate of 500 kHz and was flown in 50-100 m above ground. At this flying height the laser footprint is 25-50 mm allowing mapping of very small surface details. Furthermore, online waveform processing of the backscattered laser energy enables the retrieval of multiple targets for single laser shots resulting in a dense point cloud of

  15. Optimal lens design and use in laser-scanning microscopy

    PubMed Central

    Negrean, Adrian; Mansvelder, Huibert D.

    2014-01-01

    In laser-scanning microscopy often an off-the-shelf achromatic doublet is used as a scan lens which can reduce the available diffraction-limited field-of-view (FOV) by a factor of 3 and introduce chromatic aberrations that are scan angle dependent. Here we present several simple lens designs of superior quality that fully make use of high-NA low-magnification objectives, offering diffraction-limited imaging over a large FOV and wavelength range. We constructed a two-photon laser-scanning microscope with optimized custom lenses which had a near diffraction limit point-spread-function (PSF) with less than 3.6% variation over a 400 µm FOV and less than 0.5 µm lateral color between 750 and 1050 nm. PMID:24877017

  16. Tuning and scanning control system for high resolution alexandrite lasers

    NASA Technical Reports Server (NTRS)

    Smith, James C.; Schwemmer, Geary K.

    1988-01-01

    An alexandrite laser is spectrally narrowed and tuned by the use of three optical elements. Each element provides a successively higher degree of spectral resolution. The digitally controlled tuning and scanning control servo system simultaneously positions all three optical elements to provide continuous high resolution laser spectral tuning. The user may select manual, single, or continuous modes of automated scanning of ranges up to 3.00/cm and at scan rates up to 3.85/cm/min. Scanning over an extended range of up to 9.999/cm may be achieved if the highest resolution optic is removed from the system. The control system is also capable of being remotely operated by another computer or controller via standard RS-232 serial data link.

  17. Two-Photon Laser Scanning Stereomicroscopy for Fast Volumetric Imaging

    PubMed Central

    Yang, Yanlong; Yao, Baoli; Lei, Ming; Dan, Dan; Li, Runze; Horn, Mark Van; Chen, Xun; Li, Yang; Ye, Tong

    2016-01-01

    Bessel beams have been successfully used in two-photon laser scanning fluorescence microscopy to extend the depth of field (EDF), which makes it possible to observe fast events volumetrically. However, the depth information is lost due to integration of fluorescence signals along the propagation direction. We describe the design and implementation of two-photon lasers scanning stereomicroscopy, which allows viewing dynamic processes in three-dimensional (3D) space stereoscopically in real-time with shutter glasses at the speed of 1.4 volumes per second. The depth information can be appreciated by human visual system or be recovered with correspondence algorithms for some cases. PMID:27997624

  18. Application of in vivo laser scanning microscope in dermatology

    NASA Astrophysics Data System (ADS)

    Lademann, Juergen; Richter, H.; Otberg, N.; Lawrenz, F.; Blume-Peytavi, U.; Sterry, W.

    2003-10-01

    The state of the art of in-vivo and in-vitro penetration measurements of topically applied substances is described. Only optical techniques represent online measuring methods based on the absorption or scattering properties of the topically applied substances. Laser scanning microscopy (LSM) has become a promising method for investigations in dermatology and skin physiology, after it was possible to analyze the skin surface on any body side in-vivo. In the present paper the application of a dermatological laser scanning microscope for penetration and distribution measurements of topically applied substances is described. The intercellular and follicular penetration pathways were studied.

  19. The Laser Vegetation Imaging Sensor (LVIS): A Medium-Altitude, Digitization-Only, Airborne Laser Altimeter for Mapping Vegetation and Topography

    NASA Technical Reports Server (NTRS)

    Blair, J. Bryan; Rabine, David L.; Hofton, Michelle A.

    1999-01-01

    The Laser Vegetation Imaging Sensor (LVIS) is an airborne, scanning laser altimeter designed and developed at NASA's Goddard Space Flight Center. LVIS operates at altitudes up to 10 km above ground, and is capable of producing a data swath up to 1000 m wide nominally with 25 m wide footprints. The entire time history of the outgoing and return pulses is digitized, allowing unambiguous determination of range and return pulse structure. Combined with aircraft position and attitude knowledge, this instrument produces topographic maps with decimeter accuracy and vertical height and structure measurements of vegetation. The laser transmitter is a diode-pumped Nd:YAG oscillator producing 1064 nm, 10 nsec, 5 mJ pulses at repetition rates up to 500 Hz. LVIS has recently demonstrated its ability to determine topography (including sub-canopy) and vegetation height and structure on flight missions to various forested regions in the U.S. and Central America. The LVIS system is the airborne simulator for the Vegetation Canopy Lidar (VCL) mission (a NASA Earth remote sensing satellite due for launch in 2000), providing simulated data sets and a platform for instrument proof-of-concept studies. The topography maps and return waveforms produced by LVIS provide Earth scientists with a unique data set allowing studies of topography, hydrology, and vegetation with unmatched accuracy and coverage.

  20. Recent advances in the applications of pulsed lasers in the hydrosphere. [considering airborne bathymetry system

    NASA Technical Reports Server (NTRS)

    Hickman, G. D.

    1975-01-01

    Laboratory and field measurements have been performed on the transmission/scattering characteristics of a pulsed neon laser as a function of water turbidity. These results have been used to establish the criteria for an airborne laser bathymetry system. Extensive measurements have been made of laser induced fluorescence using a pulsed tunable dye laser. Feasibility has been demonstrated for remote detection and possible identification of various types of algae and oils. Similar measurements made on a wide variety of organic dyes have shown this technique to have applications in remote measurements of subsurface currents, temperature and salinity.

  1. Investigations in optoelectronic image processing in scanning laser microscopy

    NASA Astrophysics Data System (ADS)

    Chaliha, Hiranya Kumar

    A considerable amount of work has been done on scann-ing laser microscopy since its applications were first pointed out by Roberts and Young[1], Minsky [2] and Davidovits et al [3]. The advent of laser has made it possible to focus an intense beam of laser light in a scanning optical microscope (SOM) [4, 5] and hence explore regions of microscopy[6] uncovered by conven-tional microscopy. In the simple SOM [7, 8, 9], the upper spatial frequency in amplitude transmittance or reflectance of an object for which transfer function is nonzero is same as that in a conventional optical microscope. However, in Type II SOM [7] or confocal SOM that employs a coherent or a point detector, the spatial frequency bandwidth is twice that obtained in a conventional microscope. Besides this confocal set-up is found to be very useful in optical sectioning and consequently in 3-D image processing[10, 11, 12] specially of biological specimens. Such systems are also suitable for studies of semiconductor materials [13], super-resolution [14] and various imaginative ways of image processing[15, 16, 17] including phase imaging[18]. A brief survey of related advances in scanning optical microscopy has been covered in the chapter 1 of the thesis. The performance of SOM may be investigated by concent-rating also on signal derived by one dimensional scan of the object specimen. This simplified mode may also be adapted to give wealth of information for biological and semiconductor specimens. Hence we have investigated the design of a scanning laser system suited specifically for studies of line scan image signals of microscopic specimens when probed through a focused laser spot. An electro-mechanical method of scanning of the object specimen has been designed with this aim in mind. Chapter 2, Part A of the thesis deals with the design consider-ations of such a system. For analysis of scan signals at a later instant of time so as to facilitate further processing, an arrangement of microprocessor

  2. Photodynamic therapy with laser scanning mode of tumor irradiation

    NASA Astrophysics Data System (ADS)

    Chepurna, Oksana; Shton, Irina; Kholin, Vladimir; Voytsehovich, Valerii; Popov, Viacheslav; Pavlov, Sergii; Gamaleia, Nikolai; Wójcik, Waldemar; Zhassandykyzy, Maral

    2015-12-01

    In this study we propose a new version of photodynamic therapy performed by laser scanning. The method consists in tumor treatment by a light beam of a small cross section which incrementally moves through the chosen area with a defined delay at each point and repetitively re-scans a zone starting from the initial position. Experimental evaluation of the method in vitro on murine tumor model showed that despite the dose, applied by scanning irradiation mode, was 400 times lower, the tumor inhibition rate conceded to attained with continuous irradiation mode by only 20%.

  3. Nonmechanical axial scanning laser Doppler velocimeter with directional discrimination.

    PubMed

    Maru, Koichi; Hata, Takahiro

    2012-07-10

    An axial scanning laser Doppler velocimeter (LDV) with directional discrimination not requiring any moving mechanism in its probe is proposed. The proposed LDV utilizes frequency shift induced by acousto-optic modulators (AOMs) for discriminating the direction of velocity. The measurement position is axially scanned by changing the wavelength of the light input to the probe. The experimental result reveals that both the axial scan and the directional discrimination can be realized by using the proposed method without any moving element in the probe.

  4. An airborne laser fluorosensor for the detection of oil on water

    NASA Technical Reports Server (NTRS)

    Kim, H. H.; Hickman, G. D.

    1973-01-01

    The successful operation of an airborne laser fluorosensor system is reported that makes it possible to detect and map surface oil, either of natural-seepage or spill origin, on large bodies of water. Preliminary results indicate that the sensitivity of the instrument exceeds that of conventional passive remote sensors currently available for oil spill detection.

  5. Mapping Forest Species Composition Using Imaging Spectrometry and Airborne Laser Scanner Data

    NASA Astrophysics Data System (ADS)

    Torabzadeh, H.; Morsdorf, F.; Leiterer, R.; Schaepman, M. E.

    2013-09-01

    Accurate mapping of forest species composition is an important aspect of monitoring and management planning related to ecosystem functions and services associated with water refinement, carbon sequestration, biodiversity, and wildlife habitats. Although different vegetation species often have unique spectral signatures, mapping based on spectral reflectance properties alone is often an ill-posed problem, since the spectral signature is as well influenced by age, canopy gaps, shadows and background characteristics. Thus, reducing the unknown variation by knowing the structural parameters of different species should improve determination procedures. In this study we combine imaging spectrometry (IS) and airborne laser scanning (ALS) data of a mixed needle and broadleaf forest to differentiate tree species more accurately as single-instrument data could do. Since forest inventory data in dense forests involve uncertainties, we tried to refine them by using individual tree crowns (ITC) position and shape, which derived from ALS data. Comparison of the extracted spectra from original field data and the modified one shows how ALS-derived shape and position of ITCs can improve separablity of the different species. The spatially explicit information layers containing both the spectral and structural components from the IS and ALS datasets were then combined by using a non-parametric support vector machine (SVM) classifier.

  6. A comprehensive uncertainty analysis and method of geometric calibration for a circular scanning airborne lidar

    NASA Astrophysics Data System (ADS)

    Gonsalves, Michael Oliver

    This dissertation describes an automated technique for ascertaining the values of the geometric calibration parameters of an airborne lidar. A least squares approach is employed that adjusts the point cloud to a single planar surface which could be either a narrow airport runway or a dynamic sea surface. Going beyond the customary three boresight angles, the proposed adjustment can determine up to eleven calibration parameters to a precision that renders a negligible contribution to the point cloud's positional uncertainty. Presently under development is the Coastal Zone Mapping and Imaging Lidar (CZMIL), which, unlike most contemporary systems that use oscillating mirrors to reflect the beam, will use a circular spinning prism to refract the laser in the desired direction. This departure from the traditional scanner presents the potential for internal geometric misalignments not previously experienced. Rather than relying on past calibration practices (like requiring data be acquired over a pitched-roof), a more robust method of calibration is established which does not depend on the presence of any cultural features. To develop this new method of calibration, the laser point positioning equation for this lidar was developed first. The system was then simulated in the MATLAB environment. Using these artificial datasets, the behavior of each geometric parameter iii was systematically manipulated, understood and calibrated, while an optimal flight strategy for the calibration acquisition was simultaneously developed. Finally, the total propagated uncertainty (TPU) of the point cloud was determined using a propagation of variances. Using this TPU module, the strength of the calibration solution was assessed. For example, four flight lines each of 20 seconds in duration contained sufficient information to determine the calibration parameters to such a degree of confidence that their contribution to the final point cloud uncertainty was only 0.012m in the horizontal

  7. Airborne and spaceborne lasers for terrestrial geophysical sensing; Proceedings of the Meeting, Los Angeles, CA, Jan. 14, 15, 1988

    NASA Technical Reports Server (NTRS)

    Allario, Frank (Editor)

    1988-01-01

    The present conference on airborne and spaceborne remote sensing laser applications discusses topics in atmospheric and geophysical sciences-related sensors, lidar and DIAL component and subsystem technologies, and coherent laser experiments and semiconductor laser technologies. Attention is given to airborne lidar measurement of aerosols, a ground-based injection-locked pulsed TEA laser for wind measurements, chemical/biological agent standoff detection methods, lidars for wind shear erosion, laser tuning to selected gas absorption lines in the atmosphere, the NASA lidar-in-space technology experiment, and the Laser Atmospheric Wind Sounder.

  8. Laser airborne remote sensing real-time acquisition, processing, and control system

    NASA Astrophysics Data System (ADS)

    Kelly, Brian T.; Pierson, Robert E.; Dropka, T. J.; Dowling, James A.; Lang, L. M.; Fox, Marsha J.

    1997-10-01

    The US Air Force Phillips Laboratory is evaluating the feasibility of long-standoff-range remote sensing of gaseous species present in trace amounts in the atmosphere. Extensive system integration in the laboratory and an airborne test are leading to remote sensing ground test and airborne missions within the next year. This paper describes the design, external interfaces. and initial performance of the Laser Airborne Remote Sensing acquisition, processing, and control system to be deployed on the Phillips Laboratory NC-135 research aircraft for differential absorption lidar system performance tests. The dual-CPU VME-based real-time computer system synchronizes experiment timing and pulsed CO2 laser operation up to 30 Hz while controlling optical subsystem components such as a laser grating, receiver gain, mirror alignment, and laser shutters. This real-time system acquires high rate detector signals from the outgoing and return laser pulses as well as a low rate health and status signals form the optical bench and the aircraft. Laser pulse and status data are processed and displayed in real time on one of four graphical user interfaces: one devoted to system control, one to remote mirror alignment, and two other interfaces for real-time data analysis and diagnostics. The dual-CPU and multi- layered software decouple time critical and non-critical tasks allowing great flexibility in flight-time display and processing.

  9. Airborne laser-spark for ambient desorption/ionisation.

    PubMed

    Bierstedt, Andreas; Riedel, Jens

    2016-01-01

    A novel direct sampling ionisation scheme for ambient mass spectrometry is presented. Desorption and ionisation are achieved by a quasi-continuous laser induced plasma in air. Since there are no solid or liquid electrodes involved the ion source does not suffer from chemical interferences or fatigue originating from erosive burning or from electrode consumption. The overall plasma maintains electro-neutrality, minimising charge effects and accompanying long term drift of the charged particles trajectories. In the airborne plasma approach the ambient air not only serves as the plasma medium but at the same time also slows down the nascent ions via collisional cooling. Ionisation of the analyte molecules does not occur in the plasma itself but is induced by interaction with nascent ionic fragments, electrons and/or far ultraviolet photons in the plasma vicinity. At each individual air-spark an audible shockwave is formed, providing new reactive species, which expands concentrically and, thus, prevents direct contact of the analyte with the hot region inside the plasma itself. As a consequence the interaction volume between plasma and analyte does not exceed the threshold temperature for thermal dissociation or fragmentation. Experimentally this indirect ionisation scheme is demonstrated to be widely unspecific to the chemical nature of the analyte and to hardly result in any fragmentation of the studied molecules. A vast ensemble of different test analytes including polar and non-polar hydrocarbons, sugars, low mass active ingredients of pharmaceuticals as well as natural biomolecules in food samples directly out of their complex matrices could be shown to yield easily accessible yet meaningful spectra. Since the plasma medium is humid air, the chemical reaction mechanism of the ionisation is likely to be similar to other ambient ionisation techniques. Wir stellen hier eine neue Ionisationsmethode für die Umgebungsionisation (ambient ionisation) vor. Sowohl die

  10. FOOD SURFACE TEXTURE MEASUREMENT USING REFLECTIVE CONFOCAL LASER SCANNING MICROSCOPY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Confocal laser scanning microscopy (CLSM) was used in the reflection mode to characterize the surface texture (roughness) of sliced food surfaces. Sandpapers of grit size between 150 and 600 were used as the height reference to standardize the CLSM hardware settings. Sandpaper particle sizes were v...

  11. Calibration Design and Assessment of the Airborne Conical Scanning Millimeterwave Imaging Radiometer (CoSMIR)

    NASA Technical Reports Server (NTRS)

    Piepmeier, J. R.; Racette, P.; Walker, D. K.; Randa, J.; Krebs, Carolyn A. (Technical Monitor)

    2002-01-01

    The airborne Conical Scanning Millimeter-wave Imaging Radiometer (CoSMIR) will provide measurements useful for atmospheric studies and satellite calibration and validation (cal/val). Designed to match the tropospheric sounding channels of the Defense Meteorological Satellite Program QMSP) Special Sensor Microwave Imager/Sounder (SSMIS), the CoSMIR consists of four radiometers operating at 50-54 (3 channels - 50.3, 52.8, and 53.6), 91.655 (dual polarization), 150.0, and 193.31 (3 channels 11, 13, and 16.6) GHz. The design of CoSMIR was primarily driven by its intended initial use as an SSMIS cal/val sensor. In particular, three design features were directly affected by this requirement: frequency planning, calibration target design, and the mechanical gimbals. An initial calibration assessment of CoSMIR was performed to determine any needed improvements. We used a combination of laboratory and field measurements to do this. Laboratory measurements included comparisons to a liquid nitrogen standard, IF amplifier and diode linearity tests, LO leakage and reflection testing, and antenna to calibration target coupling tests. Results of these tests will be reported. We also performed a satellite underflight under DM SP F-15 and have compared CoSMIR imagery to SSM/T-2 and SSM/I imagery. Additional information is included in the original extended abstract.

  12. Scanning infrared remote sensing system for identification, visualization, and quantification of airborne pollutants

    NASA Astrophysics Data System (ADS)

    Harig, Roland; Matz, Gerhard; Rusch, Peter

    2002-02-01

    Remote sensing by Fourier-transform infrared (FTIR) spectrometry allows detection, identification, and quantification of airborne pollutants. In the case of leaks in pipelines or leaks in chemical plants, chemical accidents, terrorism, or war, hazardous compounds are often released into the atmosphere. Various Fourier-transform infrared spectrometers have been developed for the remote detection and identification of hazardous clouds. However, for the localization of a leak and a complete assessment of the situation in the case of the release of a hazardous cloud, information about the position and the size of a cloud is essential. Therefore, an imaging passive remote sensing system comprised of an interferometer (Bruker OPAG 22), a data acquisition, processing, and control system with a digital signal processor (FTIR DSP), an azimuth-elevation-scanning mirror, a video system with a DSP, and a personal computer has been developed. The FTIR DSP system controls the scanning mirror, collects the interferograms, and performs the Fourier transformation. The spectra are transferred to a personal computer and analyzed by a real-time identification algorithm that does not require background spectra for the analysis. The results are visualized by a video image, overlaid by false color images. For each target compound of a spectral library, images of the coefficient of correlation, the signal to noise ratio, the brightness temperature of the background, the difference between the temperature of the ambient air and the brightness temperature of the background, and the noise equivalent column density are produced. The column densities of all directions in which a target compound has been identified may be retrieved by a nonlinear least squares fitting algorithm and an additional false color image is displayed. The system has a high selectivity, low noise equivalent spectral radiance, and it allows identification, visualization, and quantification of pollutant clouds.

  13. Automating laser scanning of 3D surfaces for reverse engineering

    NASA Astrophysics Data System (ADS)

    Chan, Vincent H.; Bradley, Colin H.; Vickers, Geoffrey W.

    1997-12-01

    Application of current 3-D laser scanning systems to reverse engineering is limited by two obstacles. The meticulous guidance of the laser scanner over the surface of the object being scanned and the segmentation of the cloud data which is collected by the laser scanner. Presently, both obstacles are being manually solved. The guidance of the laser scanning sensor at the correct surface to sensor distance is dependent on operator judgement and the segmentation of the collected data is reliant on the user to manually define surface boundaries on a computer screen. By applying a 2-D CCD camera, both of these problems can be resolved. Depth information on the location of the object surface can be derived from a pair of stereo images from the CCD camera. Using this depth information, the scanner path can be automatically calculated. Segmentation of the object surface can be accomplished by employing a Kohonen neural network into the CCD image. Successful segmentation of the image is conditional on the locations selected to start neural nodes as well as the prevention of the neuron connectors from bleeding onto neighboring patches. Thus the CCD camera allows for the automatic path planning of the laser scanner as well as the segmentation of the surface into patches defined along its natural boundaries.

  14. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

  15. Scanning Web-based ICARTT File Tool (SWIFT): an online tool used to validate ICARTT-formatted airborne science data

    NASA Astrophysics Data System (ADS)

    Lucker, P. L.; Mangosing, D. C.; Chen, G.; Rinsland, P.; Brennan, J. H.; Clodius, B. F.

    2011-12-01

    The ICARTT (International Consortium for Atmospheric Research on Transport and Transformation) file format was recently endorsed by the NASA Earth Science Data Systems Standards Process Group (ESDS SPG) as a standard (ESDS-RFC-019) for specifying airborne-based Earth System Data Records (ESDR). In order to accelerate adoption of the new standard in the airborne science data community, SWIFT (Scanning Web-based ICARTT File Tool) was developed to provide a means for data providers to validate their own originated ICARTT-formatted file before submission to data archival facilities provided by NASA Langley's Atmospheric Science Data Center and the NASA Langley Airborne Science Data for Atmospheric Composition group. SWIFT builds upon a predecessor, a software utility named: FSCAN (File Scan). A major upgrade to FSCAN, the objective of SWIFT is to support all valid ICARTT files and to extract and store the file metadata in an ESDR relational database. The SWIFT-validated search metadata make it possible for COTS software and web applications to leverage the built-in spatial and temporal query capabilities of the relational database and to enable file and parameter sub-setting capabilities, as well as facilitating the generation of airborne science data merge products. These enhancements help to minimize development time of other related web applications and open up opportunities for robust data queries.

  16. Airborne Laser Sensing: A suitable tool for disaster management

    NASA Astrophysics Data System (ADS)

    Dash, J.; Steinle, E.; Baehr, H.

    Estimation of damages caused by a disaster is a major task in the post disaster mitigation process. To enhance the relief and rescue operation in the affected area it is required to get a near real time damage model. For this purpose a fast method of data acquisition with suitable methods for extracting the man-made objects are required. Laser scanning data provides the height of the ground objects, which can be used for developing models to extract the man-made features in a complex urban environment. The height variation along the boundary of trees is more significant than buildings; this parameter can be used for their classification. Segmentation of the objects was a preliminary step, where each object, which is standing above a particular height, are segmented. In the next step the contour corresponding to each segmented object was extracted. To classify these polygons into tree or building Modified Standard Deviation (SD) was determined with respect to a best fit line in the local domain i.e. calculating MSD of a sma ll number of consecutive boundary pixels at a time. Since the MSD method is a pixel based classification, so the tree part of a mixed segment can be removed in this process, which is a difficult task in the polygon based classification. Some to the tree parts were remained in the result due to their less height variation. But these can be further removed by analyzing the shape of the resulted polygons. This information can be combined with others like the vulnerability of the area to the disaster, population of the area etc. to generate a pre disaster database. After the disaster, from these specific areas where the buildings were identified in the pre disaster database, modeling of buildings should be done. The building modeling deals with generating the three dimensional models, which will provide the post disaster database. Comparing the post disaster database with the previous one the type and amount of damage can be calculated.

  17. Simultaneous ion beam profile scan using a single laser source

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Long, C.; Huang, C.; Dickson, R.; Aleksandrov, A.

    2013-01-01

    We report on the world’s first experiment of a simultaneous profile scan of the hydrogen ion (H-) beam using a laser wire system. The system was developed and brought to operational level of application at the superconducting linac of the Spallation Neutron Source accelerator complex. The laser wire profile scanner is based on a photodetachment process and therefore can be conducted on a 1-MW neutron production H- beam in a nonintrusive manner. The new simultaneous profile scanning system allows one to simultaneously measure profiles of the H- beam at nine different locations of the linac with high speed and accuracy, and therefore provides a unique tool for accelerator tuning and physics study. This paper describes the design, optical system and software platform developments, and measurement results of the simultaneous profile scanning system.

  18. Registration Procedures for Terrestrial Laser Scanning in Geomorphologic Studies

    NASA Astrophysics Data System (ADS)

    Collins, B. D.; Kayen, R.; Minasian, D.

    2006-12-01

    Terrestrial based laser scanning, from either vehicle or tripod mounts allows the collection of geomorphologic data at previously unprecedented detail and volume. However, despite the ease of collecting this data in many settings, post-processing datasets collected without laser-visible reflectors within individual scans can lead to difficulties in both registration and georeferencing procedures. We have been actively involved in gathering data sets from a number of different environments and have been developing various techniques to post-process the data using surface registration methods. These methods use the point cloud or model surface to find a best-fit of the three-dimensional terrain. Recently, we have collected laser scan data of levee breaches in New Orleans following Hurricane Katrina, a glacial cirque basin in the Canadian Rockies, a deep-seated landslide mass in Ventura County, California, rapidly evolving coastal bluffs in Central California, and sand bars and archeological sites in Grand Canyon National Park, Arizona. In each of these projects, setting up accurately surveyed reflectors was impractical due to the locations dynamic and fairly inaccessible setting. Robust surface registration procedures were therefore needed to provide accurate terrain models. We have used laser scanning results from these projects to assess the efficiency of the various post- processing methodologies for obtaining final registered and georeferenced point clouds and surface models. We compared registration results obtained both with and without accurate GPS coordinates for the laser scanner origin (Ventura and coastal landslides), use of a supporting total station unit (Grand Canyon), and collection of DGPS data on targets imaged in the LIDAR data after the scanning process (Katrina Levees). In many of these settings, the model fit improved by four times, from a root mean square error of 20 cm to 5cm when accurately surveyed coordinates were utilized for the laser scan

  19. Airborne and scanning lidar results obtained during Pacific 2001 in lhe Lower Fraser Valley of British Columbia

    NASA Astrophysics Data System (ADS)

    Strawbridge, Kevin B.

    2004-02-01

    Two different lidar platforms were employed in the Pacific 2001 field study. A simultaneous upward/downward airborne lidar system called AERIAL (AERosol Imaging Airborne Lidar) was flown aboard the National Research Council of Canada Convair 580(CV580). The primary task of this platform was to establish a regional picture of particulate matter (PM) concentrations in the Lower Fraser Valley (LFV). The high temporal and spatial resolution of the lidar provided images of PM stratification and boundary layer structure along predetermined flight lines. The flight lines were divided into a series of north-south and east-west lines to provide a snapshot of the LFV as well as provide aerial support for four ground sites. The airborne lidar system also including a cross-polarization channel that is sensitive to particle shape (non-sphericity), for example smoke plumes from forest fires. There were 9 flights flown over a 3 week period including 2 night flights. The primary purpose of the night flights was to map PM transport in the lake valleys along the north range of the LFV. A scanning lidar facility called RASCAL (Rapid Acquisition SCanning Aerosol Lidar) was part of a suite of instruments making longer term measurements at the Langley Lochiel ground site. The lidar system was programmed to take three elevation scans (west, north and east) of the troposphere from the horizon to near zenith. Measurements were conducting for approximately 16 hours per day except longer during aircraft night flights. Results from both the airborne and scanning lidar facilities will be presented.

  20. High-definition laser display system using multibeam scanning

    NASA Astrophysics Data System (ADS)

    Zhao, Zhenming; Li, Yongda; Lang, Baihe

    2000-10-01

    The design and principles of a high definition laser display system with multi-beam scanning are described. The system employs 4 laser beams each being composed of red, green and blue components. The four beams from one scanner are scanned simultaneously by a rotating polygonal mirror for horizontal deflection and by a galvanometer for vertical deflection. Compared with conventional single-beam scanning, the new design has the following advantages: 1) The rotational speed of the polygonal mirrors can be reduced by a factor of 4, which would improve the system performance and decrease the difficulties of the manufacture of the system. The size of the polygonal facet and, therefore, the laser beam diameter can be increased which would decrease the pixel diffusion. 2) The simultaneous operation of the 4 modulators would improve the horizontal resolution by a factor of 4. 3) For the same screen brightness, the single pixel power density can be reduced by a factor of 4 which would decrease the hazardous laser radiation.

  1. Hand-held digital line-scanning laser ophthalmoscope (LSLO)

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Ferguson, R. D.; Ustun, Teoman E.; Maislin, Gami; Webb, Robert H.

    2004-07-01

    Scanning laser ophthalmoscopy is a powerful research tool with specialized but, to date, limited use in ophthalmic clinics due in part to the size, cost, and complexity of instruments. Conversely, low-cost retinal imaging devices have limited capabilities in screening, detection, and diagnosis of diseases. To fill the niche between these two, a low-cost, hand-held, line-scanning laser ophthalmoscope (LSLO) was designed, constructed, and tested on normal human subjects. The LSLO has only one moving part, multiple imaging modes, and uses low-cost but highly sensitive complimentary metal oxide semiconductor (CMOS) linear arrays for imaging with a detector dynamic range of 12-bits. The line-scanning approach produces high contrast quasi-confocal images with nearly the same performance as a flying-spot SLO. Imaging modes include simultaneous dual wavelength illumination and live stereoscopic imaging with a split aperture. Image processing and display functions are controlled with two stacked prototype compact printed circuit boards using field-programmable gated arrays (FPGA) and other digital electronic elements. With near shot-noise limited performance, the digital LSLO camera requires low illumination power (~ 100 μW) at near-infrared wavelengths. Wide field fundus images with several imaging modes have been obtained from several human subjects. The LSLO will significantly enhance confocal scanning laser ophthalmoscopy for routine use by ophthalmologist, optometrists, general practitioners and also non-specialized emergency medical personnel and technicians in the field for retinal disease detection and other diverse applications.

  2. Mapping the Risk of Forest Wind Damage Using Airborne Scanning LiDAR

    NASA Astrophysics Data System (ADS)

    Saarinen, N.; Vastaranta, M.; Honkavaara, E.; Wulder, M. A.; White, J. C.; Litkey, P.; Holopainen, M.; Hyyppä, J.

    2015-03-01

    Wind damage is known for causing threats to sustainable forest management and yield value in boreal forests. Information about wind damage risk can aid forest managers in understanding and possibly mitigating damage impacts. The objective of this research was to better understand and quantify drivers of wind damage, and to map the probability of wind damage. To accomplish this, we used open-access airborne scanning light detection and ranging (LiDAR) data. The probability of wind-induced forest damage (PDAM) in southern Finland (61°N, 23°E) was modelled for a 173 km2 study area of mainly managed boreal forests (dominated by Norway spruce and Scots pine) and agricultural fields. Wind damage occurred in the study area in December 2011. LiDAR data were acquired prior to the damage in 2008. High spatial resolution aerial imagery, acquired after the damage event (January, 2012) provided a source of model calibration via expert interpretation. A systematic grid (16 m x 16 m) was established and 430 sample grid cells were identified systematically and classified as damaged or undamaged based on visual interpretation using the aerial images. Potential drivers associated with PDAM were examined using a multivariate logistic regression model. Risk model predictors were extracted from the LiDAR-derived surface models. Geographic information systems (GIS) supported spatial mapping and identification of areas of high PDAM across the study area. The risk model based on LiDAR data provided good agreement with detected risk areas (73 % with kappa-value 0,47). The strongest predictors in the risk model were mean canopy height and mean elevation. Our results indicate that open-access LiDAR data sets can be used to map the probability of wind damage risk without field data, providing valuable information for forest management planning.

  3. Binocular eye tracking with the Tracking Scanning Laser Ophthalmoscope.

    PubMed

    Stevenson, S B; Sheehy, C K; Roorda, A

    2016-01-01

    The development of high magnification retinal imaging has brought with it the ability to track eye motion with a precision of less than an arc minute. Previously these systems have provided only monocular records. Here we describe a modification to the Tracking Scanning Laser Ophthalmoscope (Sheehy et al., 2012) that splits the optical path in a way that slows the left and right retinas to be scanned almost simultaneously by a single system. A mirror placed at a retinal conjugate point redirects half of each horizontal scan line to the fellow eye. The collected video is a split image with left and right retinas appearing side by side in each frame. Analysis of the retinal motion in the recorded video provides an eye movement trace with very high temporal and spatial resolution. Results are presented from scans of subjects with normal ocular motility that fixated steadily on a green laser dot. The retinas were scanned at 4° eccentricity with a 2° square field. Eye position was extracted offline from recorded videos with an FFT based image analysis program written in Matlab. The noise level of the tracking was estimated to range from 0.25 to 0.5arcmin SD for three subjects. In the binocular recordings, the left eye/right eye difference was 1-2arcmin SD for vertical motion and 10-15arcmin SD for horizontal motion, in agreement with published values from other tracking techniques.

  4. Optics designs and system MTF for laser scanning displays

    NASA Astrophysics Data System (ADS)

    Urey, Hakan; Nestorovic, Ned; Ng, Baldwin S.; Gross, Abraham A.

    1999-07-01

    The Virtual Retinal DisplayTM (VRDTM) technology is a new display technology being developed at Microvision Inc. The displayed image is scanned onto the viewer's retina using low- power red, green, and blue light sources. Microvision's proprietary miniaturized scanner designs make VRD system very well suited for head-mounted displays. In this paper we discuss some of the advantages of the VRD technology, various ocular designs for HMD and other applications, and details of constructing a system MTF budget for laser scanning systems that includes electronics, modulators, scanners, and optics.

  5. Airborne laser swath mapping of the Denton Hills, Transantarctic Mountains, Antarctica: Applications for structural and glacial geomorphic mapping

    USGS Publications Warehouse

    Wilson, Terry; Csathó, Beata

    2007-01-01

    High-resolution digital elevation data acquired by airborne laser scanning (ALS) for the Denton Hills, along the coastal foothills of the Royal Society Range, Transantarctic Mountains, are examined for applications to bedrock and glacial geomorphic mapping. Digital elevation models (DEMs), displayed as shaded-relief images and slope maps, portray geomorphic landscape features in unprecedented detail across the region. Structures of both ductile and brittle origin, ranging in age from the Paleozoic to the Quaternary, can be mapped from the DEMs. Glacial features, providing a record of the limits of grounded ice, of lake paleoshorelines, and of proglacial lake-ice conveyor deposits, are also prominent on the DEMs. The ALS-derived topographic data have great potential for a range of mapping applications in regions of ice-free terrain in Antarctica

  6. Scanning laser system to determine the corneal shape

    NASA Astrophysics Data System (ADS)

    Ascanio, Gabriel; Caballero-Ruiz, Alberto; Ruiz-Huerta, Leopoldo; Gonzalez-Cardel, Mario; Diaz-Uribe, Rufino

    2005-07-01

    The development and tests of a scanning system to be used to determine the corneal topography with the laser deflectometry method are presented. In this equipment, a He-Ne laser beam scans the cornea by describing a spiral trajectory generated by two components: radial and angular. The first component is produced by the displacement of a plane mirror moved by a linear pneumatic actuator. The second component is produced by passing the beam through a Dove prism which is rotating by means of a belt drive coupled to a high-speed electric motor. Tests were first performed by analyzing both components independently and then they were characterized by combining the two components. Results are discussed and compared to those of an earlier cited work.

  7. Multispectral confocal scanning laser ophthalmoscope for retinal vessel oximetry

    NASA Astrophysics Data System (ADS)

    Lompado, Arthur; Smith, Matthew H.; Hillman, Lloyd W.; Denninghoff, Kurt R.

    2000-03-01

    Scanning laser microscopy is a widely used technique in ophthalmoscopy for providing high-resolution real time images of the retina. We describe a scanning laser ophthalmoscope that acquires retinal images at four wavelengths for the purpose of measuring the oxygen saturation of blood in retinal arteries and veins. Images at all four wavelengths are obtained across a single video frame using a temporal interlacing technique. An extraction procedure then permits analysis of four monochromatic images. A technique for calculating oxygen saturation from a multi-spectral image set is presented, along with preliminary measurements. The choice of wavelengths dramatically affects the oxygen saturation calculation accuracy and we present an optimized wavelength set and the calculated oxygen saturation results. The potential applications for this technology range from the diagnosis of various ophthalmic diseases to the detection of blood loss in trauma victims.

  8. The Benefits of Terrestrial Laser Scanning and Hyperspectral Data Fusion Products

    NASA Astrophysics Data System (ADS)

    Buckley, S. J.; Kurz, T. H.; Schneider, D.

    2012-10-01

    Close range hyperspectral imaging is a developing method for the analysis and identification of material composition in many applications, such as in within the earth sciences. Using compact imaging devices in the field allows near-vertical topography to be imaged, thus bypassing the key limitations of viewing angle and resolution that preclude the use of airborne and spaceborne platforms. Terrestrial laser scanning allows 3D topography to be captured with high precision and spatial resolution. The combination of 3D geometry from laser scanning, and material properties from hyperspectral imaging allows new fusion products to be created, adding new information for solving application problems. This paper highlights the advantages of terrestrial lidar and hyperspectral integration, focussing on the qualitative and quantitative aspects, with examples from a geological field application. Accurate co-registration of the two data types is required. This allows 2D pixels to be linked to the 3D lidar geometry, giving increased quantitative analysis as classified material vectors are projected to 3D space for calculation of areas and examination of spatial relationships. User interpretation of hyperspectral results in a spatially-meaningful manner is facilitated using visual methods that combine the geometric and mineralogical products in a 3D environment. Point cloud classification and the use of photorealistic modelling enhance qualitative validation and interpretation, and allow image registration accuracy to be checked. A method for texture mapping of lidar meshes with multiple image textures, both conventional digital photos and hyperspectral results, is described. The integration of terrestrial laser scanning and hyperspectral imaging is a valuable means of providing new analysis methods, suitable for many applications requiring linked geometric and chemical information.

  9. Confocal scanning laser ophthalmoscopy in glaucoma diagnosis and management.

    PubMed

    Alexandrescu, C; Dascalu, A M; Panca, A; Sescioreanu, A; Mitulescu, C; Ciuluvica, R; Voinea, L; Celea, C

    2010-01-01

    The early diagnosis and detection of progression are two key-elements in the actual management of glaucoma. The current opinion in clinical practice is to quantify the structural damage for a better follow-up of the patient and the standardization of the results. The present review is a concise survey of literature covering the period of 1990-2010, documenting the evidence-based role of confocal scanning laser ophthalmoscopy in glaucoma diagnosis and management.

  10. Compact scanning-force microscope using a laser diode

    NASA Astrophysics Data System (ADS)

    Sarid, Dror; Iams, Doug; Weissenberger, Volker; Bell, L. Stephen

    1988-12-01

    The paper describes the operation of a compact scanning-force microscope in which the gradient of force acting on a vibrating tip is monitored by a diode laser and its integrated photodiode. The system does not require reflecting or focusing elements or complicated electronics. Experimental results using this system with magnetic domains on a magnetooptic storage medium attest to the feasibility of this concept.

  11. Evaluation of microvision SD2500 scanning laser display

    NASA Astrophysics Data System (ADS)

    Harding, Thomas H.; Rash, Clarence E.; Dennis, Scott J.

    2006-05-01

    Microvision's Spectrum TM SD2500 is a candidate technology for the Modular Integrated Helmet Display System (MIHDS)program. This HMD design is intended to provide a full-color, see-through, daylight and night-readable, moderate-resolution (800X600 pixels) display. The employed technology is that of scanning lasers. This paper presents the testing results for the latest version of this prototype system.

  12. A New Multichannel Spectral Imaging Laser Scanning Confocal Microscope

    PubMed Central

    Zhang, Yunhai; Hu, Bian; Dai, Yakang; Yang, Haomin; Huang, Wei; Xue, Xiaojun; Li, Fazhi; Zhang, Xin; Jiang, Chenyu; Gao, Fei; Chang, Jian

    2013-01-01

    We have developed a new multichannel spectral imaging laser scanning confocal microscope for effective detection of multiple fluorescent labeling in the research of biological tissues. In this paper, the design and key technologies of the system are introduced. Representative results on confocal imaging, 3-dimensional sectioning imaging, and spectral imaging are demonstrated. The results indicated that the system is applicable to multiple fluorescent labeling in biological experiments. PMID:23585775

  13. Superconducting Magnet System for a Low Temperature Laser Scanning Microscope

    DTIC Science & Technology

    2006-09-22

    Our initial studies with the LTLSM bought with this equipment grant show that the intragrain critical current density crosses over with the...SUBTITLE 5a. CONTRACT NUMBER Superconducting Magnet System for a Low Temperature Laser Scanning Microscope 5b. GRANT NUMBER FA9550-05-1-0425 5c...ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Applied Superconductivity Center 1500 Engineering Drive University of Wisconsin -Madison Room 909

  14. Precision Targeting With a Tracking Adaptive Optics Scanning Laser Ophthalmoscope

    DTIC Science & Technology

    2006-01-01

    galvanometers placed at appropriate conjugates within the path of the adaptive optics scanning laser ophthalmoscope. The input to the “master” control loop is...loop is the scaled position signals from the master galvanometers . The slave tracking mirrors are placed at conjugates to the center of rotation of the...slave systems), and analog-to-digital and digital-to- analog converters (ADC and DACs) to receive reflectometer signals and drive galvanometers . The

  15. Selective retinal therapy with a continuous line scanning laser

    NASA Astrophysics Data System (ADS)

    Paulus, Yannis M.; Jain, ATul; Gariano, Ray F.; Nomoto, Hiroyuki; Schuele, Georg; Sramek, Christopher; Charalel, Resmi; Palanker, Daniel

    2010-02-01

    This study evaluates the effects of exposure duration, beam diameter, and power on the safety, selectivity, and healing of retinal lesions created using a continuous line scanning laser. A 532 nm laser (PASCALTM) with retinal beam diameters of 40 and 66 μm was applied to 60 eyes of 30 Dutch-Belted rabbits. Retinal exposure duration varied from 15 to 60 μs. Lesions were acutely assessed by ophthalmoscopy and fluorescein angiography (FA). RPE flatmounts were evaluated with live-dead fluorescent assay (LD). Histological analysis was performed at 1 hour, 1 and 3 days, 1 and 2 weeks, and 1 and 2 months following laser treatment. Ophthalmoscopic visibility (OV) of the lesions corresponded to photoreceptor damage on histological analysis at 1 hour. In subvisible lesions, FA and LD yielded similar thresholds of RPE damage. The ratios of the threshold of rupture and of OV to FA visibility (measures of safety and selectivity) increased with decreasing duration and beam diameter. Above the threshold of OV, histology showed focal RPE damage and photoreceptor loss at one day without inner retinal effects. By one week, continuity of photoreceptor and RPE layers was restored. By 1 month, photoreceptors appeared normal while hypertrophy and hyperpigmentation of the RPE persisted. Retinal therapy with a fast scanning continuous laser achieves selective targeting of the RPE and, at higher power, of the photoreceptors. The damage zone in the photoreceptor layer is quickly filled-in, likely due to photoreceptor migration from adjacent zones. Continuous scanning laser can treat large retinal areas within standard eye fixation time.

  16. Primary detection of hardwood log defects using laser surface scanning

    NASA Astrophysics Data System (ADS)

    Thomas, Edward; Thomas, Liya; Mili, Lamine; Ehrich, Roger W.; Abbott, A. Lynn; Shaffer, Clifford

    2003-05-01

    The use of laser technology to scan hardwood log surfaces for defects holds great promise for improving processing efficiency and the value and volume of lumber produced. External and internal defect detection to optimize hardwood log and lumber processing is one of the top four technological needs in the nation"s hardwood industry. The location, type, and severity of defects on hardwood logs are the key indicators of log quality and value. These visual cues provide information about internal log characteristics and products for which the log is suitable. We scanned 162 logs with a high-resolution industrial four-head laser surface scanner. The resulting data sets contain hundreds of thousands of three-dimensional coordinate points. The size of the data and noise presented special problems during processing. Robust regression models were used to fit geometric shapes to the data. The estimated orthogonal distances between the fitted model and the log surface are converted to a two-dimensional image to facilitate defect detection. Using robust regression methods and standard image processing tools we have demonstrated that severe surface defects on hardwood logs can be detected using height and contour analyses of three-dimensional laser scan data.

  17. Calibration technology in application of robot-laser scanning system

    NASA Astrophysics Data System (ADS)

    Ren, YongJie; Yin, ShiBin; Zhu, JiGui

    2012-11-01

    A system composed of laser sensor and 6-DOF industrial robot is proposed to obtain complete three-dimensional (3-D) information of the object surface. Suitable for the different combining ways of laser sensor and robot, a new method to calibrate the position and pose between sensor and robot is presented. By using a standard sphere with known radius as a reference tool, the rotation and translation matrices between the laser sensor and robot are computed, respectively in two steps, so that many unstable factors introduced in conventional optimization methods can be avoided. The experimental results show that the accuracy of the proposed calibration method can be achieved up to 0.062 mm. The calibration method is also implemented into the automated robot scanning system to reconstruct a car door panel.

  18. Laser Brazing with Beam Scanning: Experimental and Simulative Analysis

    NASA Astrophysics Data System (ADS)

    Heitmanek, M.; Dobler, M.; Graudenz, M.; Perret, W.; Göbel, G.; Schmidt, M.; Beyer, E.

    Laser beam brazing with copper based filler wire is a widely established technology for joining zinc-coated steel plates in the body-shop. Successful applications are the divided tailgate or the zero-gap joint, which represents the joint between the side panel and the roof-top of the body-in-white. These joints are in direct view to the customer, and therefore have to fulfil highest optical quality requirements. For this reason a stable and efficient laser brazing process is essential. In this paper the current results on quality improvement due to one dimensional laser beam deflections in feed direction are presented. Additionally to the experimental results a transient three-dimensional simulation model for the laser beam brazing process is taken into account. With this model the influence of scanning parameters on filler wire temperature and melt pool characteristics is analyzed. The theoretical predictions are in good accordance with the experimental results. They show that the beam scanning approach is a very promising method to increase process stability and seam quality.

  19. Novel approach towards colour imaging using a scanning laser ophthalmoscope

    PubMed Central

    Manivannan, A; Kirkpatrick, J; Sharp, P; Forrester, J

    1998-01-01

    AIMS—Conventional fundus imaging using a fundus camera produces colour fundus pictures. The scanning laser ophthalmoscope (SLO) has the advantages of lower levels of light exposure, improved contrast, and direct digital imaging but until now has produced monochromatic images as a laser of single wavelength is used. True representation of the fundus is possible by combining images taken using blue, green, and red lasers.
METHODS—A custom built SLO was used to capture blue, green, and red fundus images from suitable volunteers and patients with fundus disease. Images were corrected for eye movement and combined to form a colour image. Colour fundus photographs were taken using a fundus camera for comparison with the SLO image.
RESULTS—The background fundus and retinal vasculature had similar appearances with the two imaging modalities. Internal limiting membrane reflections were prominent with the SLO. Identification of new vessels in the diabetic fundus was easier with the SLO than the colour fundus photographs.
CONCLUSION—A colour SLO offers all the advantages of the present monochromatic imaging system with the added advantage of true colour representation of the fundus.

 Keywords: scanning laser ophthalmoscope; fundus imaging; digital colour fundus images PMID:9640178

  20. Detection and characterisation of surface cracking using scanning laser techniques

    NASA Astrophysics Data System (ADS)

    Edwards, R. S.; Clough, A. R.; Rosli, M. H.; Hernandez-Valle, J. F.; Dutton, B.

    2012-05-01

    The use of lasers for generating and detecting ultrasound is becoming more established in non-destructive testing. However, there is still scope in developing the techniques to fully realise the benefits of non-contact measurements. One application is the detection of surface defects in metals; for example, rolling contact fatigue in rails, and surface cracking on billets or plates. We present measurements using a pulsed Nd:YAG laser to generate surface ultrasonic waves and an interferometer to detect the surface displacement on the sample, and investigate the interaction of Rayleigh or Lamb waves with surface defects. Signal enhancement in the near-field is observed for Rayleigh waves when either the generator or detector is close to a defect. For a scanned detector measurement, enhancement is observed due to constructive interference of the incident and reflected waves. For a scanned generator measurement, the change in generation conditions when the laser is over the defect also lead to an enhancement. In measurements of plate samples we observe similar enhancement effects whereby higher order modes are observed when the laser is above a defect. We discuss the implications of signal enhancements for detecting and characterising surface cracking.

  1. Distance measurement to high remote targets based on the airborne chaotic laser

    NASA Astrophysics Data System (ADS)

    Kou, Renke; Wang, Haiyan; Wu, Xueming

    2016-10-01

    According to the characteristics of chaotic laser, which has ability of novel anti-jamming, high bandwidth and detecting distance of the movement target to the millimeter precision, a modeling method of using airborne chaotic laser system to detect distance of high remote targets is proposed for the first time. The characteristics of chaotic laser and principle of interferometry distance were analyzed and the model of airborne chaotic laser ranging is established. Meanwhile, the influence of detection accuracy, which inducted by the main peak width of chaotic laser and the jamming signal is analyzed. According to the results of simulation analysis, we can get conclusions that the main factors of affecting the distance measurement are transmitted power, receiving sensitivity, and various losses of transmission medium. Autocorrelation characteristic of chaotic signal can also affect the dynamic range of the whole system. The main peak width of chaotic laser is the main factor of influencing the accuracy of measurement. However, the jamming signal affect distance measuring range and accuracy of measurement little. Finally, the model's effectiveness is proved by comparing the experience data and simulation data.

  2. Segmentation of Planar Surfaces from Laser Scanning Data Using the Magnitude of Normal Position Vector for Adaptive Neighborhoods.

    PubMed

    Kim, Changjae; Habib, Ayman; Pyeon, Muwook; Kwon, Goo-rak; Jung, Jaehoon; Heo, Joon

    2016-01-22

    Diverse approaches to laser point segmentation have been proposed since the emergence of the laser scanning system. Most of these segmentation techniques, however, suffer from limitations such as sensitivity to the choice of seed points, lack of consideration of the spatial relationships among points, and inefficient performance. In an effort to overcome these drawbacks, this paper proposes a segmentation methodology that: (1) reduces the dimensions of the attribute space; (2) considers the attribute similarity and the proximity of the laser point simultaneously; and (3) works well with both airborne and terrestrial laser scanning data. A neighborhood definition based on the shape of the surface increases the homogeneity of the laser point attributes. The magnitude of the normal position vector is used as an attribute for reducing the dimension of the accumulator array. The experimental results demonstrate, through both qualitative and quantitative evaluations, the outcomes' high level of reliability. The proposed segmentation algorithm provided 96.89% overall correctness, 95.84% completeness, a 0.25 m overall mean value of centroid difference, and less than 1° of angle difference. The performance of the proposed approach was also verified with a large dataset and compared with other approaches. Additionally, the evaluation of the sensitivity of the thresholds was carried out. In summary, this paper proposes a robust and efficient segmentation methodology for abstraction of an enormous number of laser points into plane information.

  3. Segmentation of Planar Surfaces from Laser Scanning Data Using the Magnitude of Normal Position Vector for Adaptive Neighborhoods

    PubMed Central

    Kim, Changjae; Habib, Ayman; Pyeon, Muwook; Kwon, Goo-rak; Jung, Jaehoon; Heo, Joon

    2016-01-01

    Diverse approaches to laser point segmentation have been proposed since the emergence of the laser scanning system. Most of these segmentation techniques, however, suffer from limitations such as sensitivity to the choice of seed points, lack of consideration of the spatial relationships among points, and inefficient performance. In an effort to overcome these drawbacks, this paper proposes a segmentation methodology that: (1) reduces the dimensions of the attribute space; (2) considers the attribute similarity and the proximity of the laser point simultaneously; and (3) works well with both airborne and terrestrial laser scanning data. A neighborhood definition based on the shape of the surface increases the homogeneity of the laser point attributes. The magnitude of the normal position vector is used as an attribute for reducing the dimension of the accumulator array. The experimental results demonstrate, through both qualitative and quantitative evaluations, the outcomes’ high level of reliability. The proposed segmentation algorithm provided 96.89% overall correctness, 95.84% completeness, a 0.25 m overall mean value of centroid difference, and less than 1° of angle difference. The performance of the proposed approach was also verified with a large dataset and compared with other approaches. Additionally, the evaluation of the sensitivity of the thresholds was carried out. In summary, this paper proposes a robust and efficient segmentation methodology for abstraction of an enormous number of laser points into plane information. PMID:26805849

  4. Ta Keo Temple Reconstruction Based on Terrestrial Laser Scanning Technology

    NASA Astrophysics Data System (ADS)

    Xi, X.; Wang, C.; Wan, Y. P.; Khuon, K. N.

    2015-08-01

    Ta Keo temple is one of the very famous temple complex of Angkor Wat in northwestern Cambodia. It has been suffering massive collapse and other serious damages in recent years. Nowadays, Terrestrial Laser Scanning(TLS) technology is considered as a wellestablished resource for heritage documentation and protection (Lerma et al, 2008; Reshetyuk, 2009). This paper used TLS to reconstruct Ta Keo Temple. Firstly, we acquired 71 scanning stations of points cloud data with high density and high accuracy, and over one thousand images with high spatial resolution about the temple. Secondly, the raw points cloud data were denoised, reduced and managed efficiently, and registrated using an adjusted ICP algorithm. Thirdly, a triangulation method was used to model most objects. At last, we mapped the texture data into the digital model and a 3-D model of Ta Keo with high accuracy was achieved. The authors focus on large object reconstruction by TLS technology, and pay much attention to the scanning design, multi-station data and the whole project's data registration, and texture mapping and so on. The research result will be useful for Ta Keo restoration, reconstruction and protection. Also, it is a good reference source for large complex buildings reconstruction when using terrestrial laser scanning technology.

  5. Super-Resolution Laser Scanning Microscopy through Spatiotemporal Modulation

    PubMed Central

    Lu, Ju; Min, Wei; Conchello, José-Angel; Xie, Xiaoliang Sunney; Lichtman, Jeff W.

    2009-01-01

    Super-resolution optical microscopy has attracted great interest among researchers in many fields, especially in biology where the scale of physical structures and molecular processes fall below the diffraction limit of resolution for light. As one of the emerging techniques, structured illumination microscopy can double the resolution by shifting unresolvable spatial frequencies into the pass-band of the microscope through spatial frequency mixing with a wide-field structured illumination pattern. However, such a wide-field scheme typically can only image optically thin samples and is incompatible with multiphoton processes such as two-photon fluorescence, which require point scanning with a focused laser beam. Here, we propose two new super-resolution schemes for laser scanning microscopy by generalizing the concept of a spatially nonuniform imaging system. One scheme, scanning patterned illumination (SPIN) microscopy, employs modulation of the excitation combined with temporally cumulative imaging by a nondescanned array detector. The other scheme, scanning patterned detection (SPADE) microscopy, utilizes detection modulation together with spatially cumulative imaging, in this case by a nondescanned single-element detector. When combined with multiphoton excitation, both schemes can image thick samples with three-dimensional optical sectioning and much improved resolution. PMID:19743870

  6. Terrestrial laser scanning observations of geomorphic changes and varying lava lake levels at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Jones, Laura K.; Kyle, Philip R.; Oppenheimer, Clive; Frechette, Jedediah D.; Okal, Marianne H.

    2015-03-01

    A Terrestrial Laser Scanning (TLS) instrument was used to image the topography of the Main Crater at Erebus volcano each December in 2008, 2009, and 2010. Our high-spatial resolution TLS scans provide unique insights into annual and decadal scale geomorphic evolution of the summit area when integrated with comparable data collected by an airborne instrument in 2001. We observe both a pattern of subsidence within the Inner Crater of the volcano and an ~ 3 m per-year drop in the lava lake level over the same time period that are suggestive of decreasing overpressure in an underlying magma reservoir. We also scanned the active phonolite lava lake hosted within the Inner Crater, and recorded rapid cyclic fluctuations in the level of the lake. These were sporadically interrupted by minor explosions by bursting gas bubbles at the lake surface. The TLS data permit calculation of lake level rise and fall speeds and associated rates of volumetric change within the lake. These new observations, when considered with prior determinations of rates of lake surface motion and gas output, are indicative of unsteady magma flow in the conduit and its associated variability in gas volume fraction.

  7. Point-to-plane registration of terrestrial laser scans

    NASA Astrophysics Data System (ADS)

    Grant, Darion; Bethel, James; Crawford, Melba

    2012-08-01

    The registration of pairs of Terrestrial Laser Scanning data (TLS) is an integral precursor to 3D data analysis. Of specific interest in this research work is the class of approaches that is considered to be fine registration and which does not require any targets or tie points. This paper presents a pairwise fine registration approach called P2P that is formulated using the General Least Squares adjustment model. Given some initial registration parameters, the proposed P2P approach utilizes the scanned points and estimated planar features of both scans, along with their stochastic properties. These quantities are used to determine the optimum registration parameters in the least squares sense. The proposed P2P approach was tested on both simulated and real TLS data, and experimental results showed it to be four times more accurate than the registration approach of Chen and Medioni (1991).

  8. Composition analysis by scanning femtosecond laser ultraprobing (CASFLU).

    DOEpatents

    Ishikawa, Muriel Y.; Wood, Lowell L.; Campbell, E. Michael; Stuart, Brent C.; Perry, Michael D.

    2002-01-01

    The composition analysis by scanning femtosecond ultraprobing (CASFLU) technology scans a focused train of extremely short-duration, very intense laser pulses across a sample. The partially-ionized plasma ablated by each pulse is spectrometrically analyzed in real time, determining the ablated material's composition. The steering of the scanned beam thus is computer directed to either continue ablative material-removal at the same site or to successively remove nearby material for the same type of composition analysis. This invention has utility in high-speed chemical-elemental, molecular-fragment and isotopic analyses of the microstructure composition of complex objects, e.g., the oxygen isotopic compositions of large populations of single osteons in bone.

  9. Airborne Laser/GPS Mapping of Assateague National Seashore Beach

    NASA Technical Reports Server (NTRS)

    Kradill, W. B.; Wright, C. W.; Brock, John C.; Swift, R. N.; Frederick, E. B.; Manizade, S. S.; Yungel, J. K.; Martin, C. F.; Sonntag, J. G.; Duffy, Mark; Hulslander, William

    1997-01-01

    Results are presented from topographic surveys of the Assateague Island National Seashore using recently developed Airborne Topographic Mapper (ATM) and kinematic Global Positioning System (GPS) technology. In November, 1995, and again in May, 1996, the NASA Arctic Ice Mapping (AIM) group from the Goddard Space Flight Center's Wallops Flight Facility conducted the topographic surveys as a part of technology enhancement activities prior to conducting missions to measure the elevation of extensive sections of the Greenland Ice Sheet as part of NASA's Global Climate Change program. Differences between overlapping portions of both surveys are compared for quality control. An independent assessment of the accuracy of the ATM survey is provided by comparison to surface surveys which were conducted using standard techniques. The goal of these projects is to mdke these measurements to an accuracy of +/- 10 cm. Differences between the fall 1995 and 1996 surveys provides an assessment of net changes in the beach morphology over an annual cycle.

  10. Diameter distribution estimation with laser scanning based multisource single tree inventory

    NASA Astrophysics Data System (ADS)

    Kankare, Ville; Liang, Xinlian; Vastaranta, Mikko; Yu, Xiaowei; Holopainen, Markus; Hyyppä, Juha

    2015-10-01

    Tree detection and tree species recognition are bottlenecks of the airborne remote sensing-based single tree inventories. The effect of these factors in forest attribute estimation can be reduced if airborne measurements are aided with tree mapping information that is collected from the ground. The main objective here was to demonstrate the use of terrestrial laser scanning-derived (TLS) tree maps in aiding airborne laser scanning-based (ALS) single tree inventory (multisource single tree inventory, MS-STI) and its capability in predicting diameter distribution in various forest conditions. Automatic measurement of TLS point clouds provided the tree maps and the required reference information from the tree attributes. The study area was located in Evo, Finland, and the reference data was acquired from 27 different sample plots with varying forest conditions. The workflow of MS-STI included: (1) creation of automatic tree map from TLS point clouds, (2) automatic diameter at breast height (DBH) measurement from TLS point clouds, (3) individual tree detection (ITD) based on ALS, (4) matching the ITD segments to the field-measured reference, (5) ALS point cloud metric extraction from the single tree segments and (6) DBH estimation based on the derived metrics. MS-STI proved to be accurate and efficient method for DBH estimation and predicting diameter distribution. The overall accuracy (root mean squared error, RMSE) of the DBH was 36.9 mm. Results showed that the DBH accuracy decreased if the tree density (trees/ha) increased. The highest accuracies were found in old-growth forests (tree densities less than 500 stems/ha). MS-STI resulted in the best accuracies regarding Norway spruce (Picea abies (L.) H. Karst.)-dominated forests (RMSE of 29.9 mm). Diameter distributions were predicted with low error indices, thereby resulting in a good fit compared to the reference. Based on the results, diameter distribution estimation with MS-STI is highly dependent on the forest

  11. Creation of a Digital Surface Model and Extraction of Coarse Woody Debris from Terrestrial Laser Scans in an Open Eucalypt Woodland

    NASA Astrophysics Data System (ADS)

    Muir, J.; Phinn, S. R.; Armston, J.; Scarth, P.; Eyre, T.

    2014-12-01

    Coarse woody debris (CWD) provides important habitat for many species and plays a vital role in nutrient cycling within an ecosystem. In addition, CWD makes an important contribution to forest biomass and fuel loads. Airborne or space based remote sensing instruments typically do not detect CWD beneath the forest canopy. Terrestrial laser scanning (TLS) provides a ground based method for three-dimensional (3-D) reconstruction of surface features and CWD. This research produced a 3-D reconstruction of the ground surface and automatically classified coarse woody debris from registered TLS scans. The outputs will be used to inform the development of a site-based index for the assessment of forest condition, and quantitative assessments of biomass and fuel loads. A survey grade terrestrial laser scanner (Riegl VZ400) was used to scan 13 positions, in an open eucalypt woodland site at Karawatha Forest Park, near Brisbane, Australia. Scans were registered, and a digital surface model (DSM) produced using an intensity threshold and an iterative morphological filter. The DSMs produced from single scans were compared to the registered multi-scan point cloud using standard error metrics including: Root Mean Squared Error (RMSE), Mean Squared Error (MSE), range, absolute error and signed error. In addition the DSM was compared to a Digital Elevation Model (DEM) produced from Airborne Laser Scanning (ALS). Coarse woody debris was subsequently classified from the DSM using laser pulse properties, including: width and amplitude, as well as point spatial relationships (e.g. nearest neighbour slope vectors). Validation of the coarse woody debris classification was completed using true-colour photographs co-registered to the TLS point cloud. The volume and length of the coarse woody debris was calculated from the classified point cloud. A representative network of TLS sites will allow for up-scaling to large area assessment using airborne or space based sensors to monitor forest

  12. Airborne dual laser excitation and mapping of phytoplankton photopigments in a Gulf Stream Warm Core Ring

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1983-01-01

    Utilization of a two-color airborne lidar system in the systematic study of a major oceanographic feature is reported here for the first time. An excimer pumped dye laser was optically and electronically integrated into the NASA Airborne Oceanographic Lidar for simultaneous use with a frequency doubled Nd:YAG laser. The output beams exit the laser system along parallel paths after being produced on an alternating pulse basis at a combined rate of 12.5 pps. Results are presented for missions flown over a Gulf Stream Warm Core Ring (WCR) as well as over shelf, slope, Gulf Stream, and Sargasso Sea waters. From the airborne data a high coherence is shown between the two-color chlorophyll a data and between the Nd:YAG chlorophyll a and phycoerythrin responses within each of these water masses. However, distinct differences in the response patterns of these photopigments are shown to exist between the differing water masses. At certain of the boundaries separating the water masses a sharp transition is seen to occur, while at others a wider transition zone was observed in which the correlation between the photopigments appears to degrade.

  13. Portable Airborne Laser System Measures Forest-Canopy Height

    NASA Technical Reports Server (NTRS)

    Nelson, Ross

    2005-01-01

    (PALS) is a combination of laser ranging, video imaging, positioning, and data-processing subsystems designed for measuring the heights of forest canopies along linear transects from tens to thousands of kilometers long. Unlike prior laser ranging systems designed to serve the same purpose, the PALS is not restricted to use aboard a single aircraft of a specific type: the PALS fits into two large suitcases that can be carried to any convenient location, and the PALS can be installed in almost any local aircraft for hire, thereby making it possible to sample remote forests at relatively low cost. The initial cost and the cost of repairing the PALS are also lower because the PALS hardware consists mostly of commercial off-the-shelf (COTS) units that can easily be replaced in the field. The COTS units include a laser ranging transceiver, a charge-coupled-device camera that images the laser-illuminated targets, a differential Global Positioning System (dGPS) receiver capable of operation within the Wide Area Augmentation System, a video titler, a video cassette recorder (VCR), and a laptop computer equipped with two serial ports. The VCR and computer are powered by batteries; the other units are powered at 12 VDC from the 28-VDC aircraft power system via a low-pass filter and a voltage converter. The dGPS receiver feeds location and time data, at an update rate of 0.5 Hz, to the video titler and the computer. The laser ranging transceiver, operating at a sampling rate of 2 kHz, feeds its serial range and amplitude data stream to the computer. The analog video signal from the CCD camera is fed into the video titler wherein the signal is annotated with position and time information. The titler then forwards the annotated signal to the VCR for recording on 8-mm tapes. The dGPS and laser range and amplitude serial data streams are processed by software that displays the laser trace and the dGPS information as they are fed into the computer, subsamples the laser range and

  14. A new pulsed laser deposition technique: Scanning multi-component pulsed laser deposition method

    SciTech Connect

    Fischer, D.; Jansen, M.; Fuente, G. F. de la

    2012-04-15

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 deg. C.

  15. A new pulsed laser deposition technique: scanning multi-component pulsed laser deposition method.

    PubMed

    Fischer, D; de la Fuente, G F; Jansen, M

    2012-04-01

    The scanning multi-component pulsed laser deposition (PLD) method realizes uniform depositions of desired coatings by a modified pulsed laser deposition process, preferably with a femto-second laser-system. Multi-component coatings (single or multilayered) are thus deposited onto substrates via laser induced ablation of segmented targets. This is achieved via horizontal line-scanning of a focused laser beam over a uniformly moving target's surface. This process allows to deposit the desired composition of the coating simultaneously, starting from the different segments of the target and adjusting the scan line as a function of target geometry. The sequence and thickness of multilayers can easily be adjusted by target architecture and motion, enabling inter/intra layer concentration gradients and thus functional gradient coatings. This new, simple PLD method enables the achievement of uniform, large-area coatings. Case studies were performed with segmented targets containing aluminum, titanium, and niobium. Under the laser irradiation conditions applied, all three metals were uniformly ablated. The elemental composition within the rough coatings obtained was fixed by the scanned area to Ti-Al-Nb = 1:1:1. Crystalline aluminum, titanium, and niobium were found to coexist side by side at room temperature within the substrate, without alloy formation up to 600 °C.

  16. Theoretical simulation of a 2 micron airborne solid state laser anemometer

    NASA Technical Reports Server (NTRS)

    Imbert, Beatrice; Cariou, Jean-Pierre

    1992-01-01

    In the near future, military aircraft will need to know precisely their true airspeed in order to optimize flight conditions. In comparison with classical anemometer probes, an airborne Doppler lidar allows measurement of the air velocity without influence from aircraft aerodynamic disturbance. While several demonstration systems of heterodyne detection using a CO2 laser have been reported, improvements in the technology of solid state lasers have recently opened up the possibility that these devices can be used as an alternative to CO2 laser systems. In particular, a diode pumped Tm:Ho:YAG laser allows a reliable compact airborne system with an eye safe wavelength (lambda = 2.09 microns) to be achieved. The theoretical study of performances of a coherent lidar using a solid state diode pumped Tm:Ho:YAG laser, caled SALSA, for measuring aircraft airspeed relative to atmospheric aerosols is described. A computer simulation was developed in order to modelize the Doppler anemometer in the function of atmospheric propagation and optical design. A clever analysis of the power budget on the detector area allows optical characteristic parameters of the system to be calculated, and then it can be used to predict performances of the Doppler system. Estimating signal to noise ratios (SNR) and heterodyne efficiency provides the available energy of speed measurement as well as a useful measurement of the alignment of the backscattered and reference fields on the detector.

  17. Laser cutting of irregular shape object based on stereo vision laser galvanometric scanning system

    NASA Astrophysics Data System (ADS)

    Qi, Li; Zhang, Yixin; Wang, Shun; Tang, Zhiqiang; Yang, Huan; Zhang, Xuping

    2015-05-01

    Irregular shape objects with different 3-dimensional (3D) appearances are difficult to be shaped into customized uniform pattern by current laser machining approaches. A laser galvanometric scanning system (LGS) could be a potential candidate since it can easily achieve path-adjustable laser shaping. However, without knowing the actual 3D topography of the object, the processing result may still suffer from 3D shape distortion. It is desirable to have a versatile auxiliary tool that is capable of generating 3D-adjusted laser processing path by measuring the 3D geometry of those irregular shape objects. This paper proposed the stereo vision laser galvanometric scanning system (SLGS), which takes the advantages of both the stereo vision solution and conventional LGS system. The 3D geometry of the object obtained by the stereo cameras is used to guide the scanning galvanometers for 3D-shape-adjusted laser processing. In order to achieve precise visual-servoed laser fabrication, these two independent components are integrated through a system calibration method using plastic thin film target. The flexibility of SLGS has been experimentally demonstrated by cutting duck feathers for badminton shuttle manufacture.

  18. Laser measurement of extinction coefficients of highly absorbing liquids. [airborne oil spill monitoring application

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Kincaid, J. S.

    1980-01-01

    A coaxial dual-channel laser system has been developed for the measurement of extinction coefficients of highly absorbing liquids. An empty wedge-shaped sample cell is first translated laterally through a He-Ne laser beam to measure the differential thickness using interference fringes in reflection. The wedge cell is carefully filled with the oil sample and translated through the coaxially positioned dye laser beam for the differential attenuation or extinction measurement. Optional use of the instrumentation as a single-channel extinction measurement system and also as a refractometer is detailed. The system and calibration techniques were applied to the measurement of two crude oils whose extinction values were required to complete the analysis of airborne laser data gathered over four controlled spills.

  19. Airborne Lidar measurements of the atmospheric pressure profile with tunable Alexandrite lasers

    NASA Technical Reports Server (NTRS)

    Korb, C. L.; Schwemmer, G. K.; Dombrowski, M.; Milrod, J.; Walden, H.

    1986-01-01

    The first remote measurements of the atmospheric pressure profile made from an airborne platform are described. The measurements utilize a differential absorption lidar and tunable solid state Alexandrite lasers. The pressure measurement technique uses a high resolution oxygen A band where the absorption is highly pressure sensitive due to collision broadening. Absorption troughs and regions of minimum absorption were used between pairs of stongly absorption lines for these measurements. The trough technique allows the measurement to be greatly desensitized to the effects of laser frequency instabilities. The lidar system was set up to measure pressure with the on-line laser tuned to the absorption trough at 13147.3/cm and with the reference laser tuned to a nonabsorbing frequency near 13170.0/cm. The lidar signal returns were sampled with a 200 range gate (30 vertical resoltion) and averaged over 100 shots.

  20. Three-dimensional dental cast analyzing system using laser scanning.

    PubMed

    Kuroda, T; Motohashi, N; Tominaga, R; Iwata, K

    1996-10-01

    The purpose of this article is to introduce the outline of our newly developed three-dimensional dental cast analyzing system with laser scanning, and its preliminary clinical applications. The system is composed of a measuring device with a slit-ray laser projector and two sets of coupled charged devised video cameras, an image processing unit, a 16-bit personal computer as a controller, and an engineering workstation as a post processor. The dental cast is projected and scanned with a slit-ray laser beam. The raster coordinates of the target are determined with an image processor. Triangulation is applied to determine the location of each point. Generation of three-dimensional graphics of the dental cast takes approximately 40 minutes. About 90,000 sets of X, Y, Z coordinates are stored in the main memory of the microcomputer. The measurement error is less than 0.05 mm. Besides the conventional linear and angular measurements of the dental cast, we are also able to demonstrate the size of the palatal surface area and the volume of the oral cavity. The advantage of this system is that it facilitates the otherwise complicated and time-consuming mock surgery necessary for treatment planning in orthognathic surgery.

  1. Efficient terrestrial laser scan segmentation exploiting data structure

    NASA Astrophysics Data System (ADS)

    Mahmoudabadi, Hamid; Olsen, Michael J.; Todorovic, Sinisa

    2016-09-01

    New technologies such as lidar enable the rapid collection of massive datasets to model a 3D scene as a point cloud. However, while hardware technology continues to advance, processing 3D point clouds into informative models remains complex and time consuming. A common approach to increase processing efficiently is to segment the point cloud into smaller sections. This paper proposes a novel approach for point cloud segmentation using computer vision algorithms to analyze panoramic representations of individual laser scans. These panoramas can be quickly created using an inherent neighborhood structure that is established during the scanning process, which scans at fixed angular increments in a cylindrical or spherical coordinate system. In the proposed approach, a selected image segmentation algorithm is applied on several input layers exploiting this angular structure including laser intensity, range, normal vectors, and color information. These segments are then mapped back to the 3D point cloud so that modeling can be completed more efficiently. This approach does not depend on pre-defined mathematical models and consequently setting parameters for them. Unlike common geometrical point cloud segmentation methods, the proposed method employs the colorimetric and intensity data as another source of information. The proposed algorithm is demonstrated on several datasets encompassing variety of scenes and objects. Results show a very high perceptual (visual) level of segmentation and thereby the feasibility of the proposed algorithm. The proposed method is also more efficient compared to Random Sample Consensus (RANSAC), which is a common approach for point cloud segmentation.

  2. Fusion of Terrestrial and Airborne Laser Data for 3D modeling Applications

    NASA Astrophysics Data System (ADS)

    Mohammed, Hani Mahmoud

    This thesis deals with the 3D modeling phase of the as-built large BIM projects. Among several means of BIM data capturing, such as photogrammetric or range tools, laser scanners have been one of the most efficient and practical tool for a long time. They can generate point clouds with high resolution for 3D models that meet nowadays' market demands. The current 3D modeling projects of as-built BIMs are mainly focused on using one type of laser scanner data, such as Airborne or Terrestrial. According to the literatures, no significant (few) efforts were made towards the fusion of heterogeneous laser scanner data despite its importance. The importance of the fusion of heterogeneous data arises from the fact that no single type of laser data can provide all the information about BIM, especially for large BIM projects that are existing on a large area, such as university buildings, or Heritage places. Terrestrial laser scanners are able to map facades of buildings and other terrestrial objects. However, they lack the ability to map roofs or higher parts in the BIM project. Airborne laser scanner on the other hand, can map roofs of the buildings efficiently and can map only small part of the facades. Short range laser scanners can map the interiors of the BIM projects, while long range scanners are used for mapping wide exterior areas in BIM projects. In this thesis the long range laser scanner data obtained in the Stop-and-Go mapping mode, the short range laser scanner data, obtained in a fully static mapping mode, and the airborne laser data are all fused together to bring a complete effective solution for a large BIM project. Working towards the 3D modeling of BIM projects, the thesis framework starts with the registration of the data, where a new fast automatic registration algorithm were developed. The next step is to recognize the different objects in the BIM project (classification), and obtain 3D models for the buildings. The last step is the development of an

  3. Using Airborne Laser Altimetry to Detect Topographic Change at Long Valley Caldera California

    NASA Technical Reports Server (NTRS)

    Hofton, M. A.; Minster, J.-B.; Ridgway, J. R.; Williams, N. P.; Blair, J. B.; Rabine, D. L.; Bufton, J. L.

    2000-01-01

    The topography of the Long Valley caldera, California, was sampled using airborne laser altimetry in 1993, 1995, and 1997 to test the feasibility of using airborne laser altimetry for monitoring deformation of volcanic origin. Results show the laser altimeters are able to resolve subtle topographic features such as a gradual slope and to detect small transient changes in lake elevation. Crossover and repeat pass analyses of laser tracks indicate decimeter-level vertical precision is obtained over flat and low-sloped terrain for altimeter systems performing waveform digitization. Comparisons with complementary, ground-based CPS data at a site close to Bishop airport indicate that the laser and GPS-derived elevations agree to within the error inherent in the measurement and that horizontal locations agree to within the radius of the laser footprint. A comparison of the data at two sites, one where no change and the other where the maximum amount of vertical uplift is expected, indicates approximately 10 cm of relative uplift occurred 1993-1997, in line with predictions from continuous CPS measurements in the region. Extensive terrain mapping flights during the 1995 and 1997 missions demonstrate some of the unique abilities of laser altimetry; the straightforward creation of high resolution, high accuracy digital elevation models of overflown terrain, and the ability to determine ground topography in the presence of significant ground cover such as dense tree canopies. These capabilities make laser altimetry an attractive technique for quantifying topographic change of volcanic origin, especially in forested regions of the world where other remote sensing instruments have difficulty detecting the underlying topography.

  4. Derivation of Ground Surface and Vegetation in a Coastal Florida Wetland with Airborne Laser Technology

    USGS Publications Warehouse

    Raabe, Ellen A.; Harris, Melanie S.; Shrestha, Ramesh L.; Carter, William E.

    2008-01-01

    The geomorphology and vegetation of marsh-dominated coastal lowlands were mapped from airborne laser data points collected on the Gulf Coast of Florida near Cedar Key. Surface models were developed using low- and high-point filters to separate ground-surface and vegetation-canopy intercepts. In a non-automated process, the landscape was partitioned into functional landscape units to manage the modeling of key landscape features in discrete processing steps. The final digital ground surface-elevation model offers a faithful representation of topographic relief beneath canopies of tidal marsh and coastal forest. Bare-earth models approximate field-surveyed heights by + 0.17 m in the open marsh and + 0.22 m under thick marsh or forest canopy. The laser-derived digital surface models effectively delineate surface features of relatively inaccessible coastal habitats with a geographic coverage and vertical detail previously unavailable. Coastal topographic details include tidal-creek tributaries, levees, modest topographic undulations in the intertidal zone, karst features, silviculture, and relict sand dunes under coastal-forest canopy. A combination of laser-derived ground-surface and canopy-height models and intensity values provided additional mapping capabilities to differentiate between tidal-marsh zones and forest types such as mesic flatwood, hydric hammock, and oak scrub. Additional derived products include fine-scale shoreline and topographic profiles. The derived products demonstrate the capability to identify areas of concern to resource managers and unique components of the coastal system from laser altimetry. Because the very nature of a wetland system presents difficulties for access and data collection, airborne coverage from remote sensors has become an accepted alternative for monitoring wetland regions. Data acquisition with airborne laser represents a viable option for mapping coastal topography and for evaluating habitats and coastal change on marsh

  5. Angular line scanning deflectometry using a laser pico projector

    NASA Astrophysics Data System (ADS)

    Zhan, Hao-Xun; Liang, Chao-Wen; Chien, Shih-Che

    2016-08-01

    In our previous publications, we had successfully made a deflectometry measurement by using a portable laser projector. In this research, we propose the beam weighting centroid method rather than previous the phase shifting method for quantification of the angular direction of the testing beam in the tested optics entrance pupil. By projecting the angular sequential lines on tested optics entrance pupil, the wavefront aberration is reconstructed from two orthogonal directions measurements, in a similar way to the line scanning deflectometry. The limited gray scale problem of laser projector during the phase shifting measurement is therefore eliminated. The reconstructed wavefront is proven to yield a more accurate result than the phase shifting methods at the cost of more image frames and acquisition time.

  6. Road Orthophoto/dtm Generation from Mobile Laser Scanning

    NASA Astrophysics Data System (ADS)

    Vallet, B.; Papelard, J.-P.

    2015-08-01

    This paper proposes a pipeline to produce road orthophoto and DTM from Mobile Laser Scanning (MLS). For the ortho, modern laser scanners provide a reflectance information allowing for high quality grayscale images, at a much finer resolution than aerial photography can offer. For DTM, MLS offers a much higher accuracy and density than aerial products. This increased precision and resolution leverages new applications for both ortho and DEM. The first task is to filter ground vs non ground, then an interpolation is conducted to build image tiles from the filtered points. Finally, multiple layers are registered and blended to allow for seamless fusion. Our proposed approach achieves high quality products and scaling up is demonstrated.

  7. Scanning laser ophthalmoscopy: optimized testing strategies for psychophysics

    NASA Astrophysics Data System (ADS)

    Van de Velde, Frans J.

    1996-12-01

    Retinal function can be evaluated with the scanning laser ophthalmoscope (SLO). the main advantage is a precise localization of the psychophysical stimulus on the retina. Four alternative forced choice (4AFC) and parameter estimation by sequential testing (PEST) are classic adaptive algorithms that have been optimized for use with the SLO, and combined with strategies to correct for small eye movements. Efficient calibration procedures are essential for quantitative microperimetry. These techniques measure precisely visual acuity and retinal sensitivity at distinct locations on the retina. A combined 632 nm and IR Maxwellian view illumination provides a maximal transmittance through the ocular media and has a animal interference with xanthophyll or hemoglobin. Future modifications of the instrument include the possibility of binocular evaluation, Maxwellian view control, fundus tracking using normalized gray-scale correlation, and microphotocoagulation. The techniques are useful in low vision rehabilitation and the application of laser to the retina.

  8. Laser light scan analysis of the “anticonvulsant face”

    PubMed Central

    Orup, H. Ivan; Deutsch, Curtis K.; Holmes, Lewis B.

    2014-01-01

    BACKGROUND The “anticonvulsant face”, comprised of a short nose, low nasal bridge, epicanthal folds, and wide mouth, was suggested in the 1970s to indicate teratogenesis caused by the anticonvulsant drugs phenytoin and phenobarbital. However, these were based on subjective clinical observations. In the present study we have applied objective and reliable quantitative measures to the operational definitions of craniofacial features in anticonvulant-exposed cases. We have adopted anthropometric analysis based on image analysis of laser light scans. Using morphometric methods, we established the positions of physical features and objectively determined the changes in the size and shape of affected soft tissues of the faces of children exposed to those anticonvulsant drugs during pregnancy. METHODS Thirteen individuals, exposed throughout pregnancy to phenytoin as either monotherapy or polytherapy, were identified in a previous analysis as having significant changes in their craniofacial features based on measurements of cephalometric radiographs, changes associated with “the anticonvulsant face”.. The soft tissues of their faces were imaged by 3D laser (structured light) scanning. RESULTS The notable changes in soft tissues identified by laser light scans were a wide philtrum (between the left and right cristae philtri), narrow mouth (between the left and right cheilions), short nasal bridge (between nasale and pronasale), short nose height (between the nasale and subnasale), and flat orbits (based on the orbital protrusion index). CONCLUSIONS This analysis of phenytoin-exposed individuals is the first anthropometric analysis of the craniofacial surface, designed to render the identification of abnormal features both objective and realiable. These analyses demonstrated that there were several significant changes in the soft tissue of the face, corroborating earlier studies of alterations of the craniofacial skeleton in the anticonvulsant face. Two of the

  9. Galvanometer beam-scanning system for laser fiber drawing.

    PubMed

    Oehrle, R C

    1979-02-15

    A major difficulty in using a laser to draw optical fibers from a glass preform has been uniformally distributing the laser's energy around the melt zone. Several systems have evolved in recent years, but to date the most successful technique has been the off-axis rotating lens system (RLS). The inability of this device to structure efficiently and dynamically the heat zone longitudinally along the preform has restricted its use to preform of less than 8-mm diameter. A new technique reported here employs two orthogonal mounted mirrors, driven by galvanometers to distribute the laser energy around the preform. This system can be retrofitted into the RLS to replace the rotating lens element. The new system, the galvanometer scanning system (GSS), operates at ten times the rotational speed of the RLS and can instantaneously modify the melt zone. The ability of the GSS to enlarge the melt zone reduces the vaporization rate at the surface of the preform permitting efficient use of higher laser power. Experiments i dicate that fibers can be drawn from significantly larger preforms by using the expanded heat zone provided by the GSS.

  10. Scanning laser beam displays based on a 2D MEMS

    NASA Astrophysics Data System (ADS)

    Niesten, Maarten; Masood, Taha; Miller, Josh; Tauscher, Jason

    2010-05-01

    The combination of laser light sources and MEMS technology enables a range of display systems such as ultra small projectors for mobile devices, head-up displays for vehicles, wearable near-eye displays and projection systems for 3D imaging. Images are created by scanning red, green and blue lasers horizontally and vertically with a single two-dimensional MEMS. Due to the excellent beam quality of laser beams, the optical designs are efficient and compact. In addition, the laser illumination enables saturated display colors that are desirable for augmented reality applications where a virtual image is used. With this technology, the smallest projector engine for high volume manufacturing to date has been developed. This projector module has a height of 7 mm and a volume of 5 cc. The resolution of this projector is WVGA. No additional projection optics is required, resulting in an infinite focus depth. Unlike with micro-display projection displays, an increase in resolution will not lead to an increase in size or a decrease in efficiency. Therefore future projectors can be developed that combine a higher resolution in an even smaller and thinner form factor with increased efficiencies that will lead to lower power consumption.

  11. Quantitative single-molecule imaging by confocal laser scanning microscopy.

    PubMed

    Vukojevic, Vladana; Heidkamp, Marcus; Ming, Yu; Johansson, Björn; Terenius, Lars; Rigler, Rudolf

    2008-11-25

    A new approach to quantitative single-molecule imaging by confocal laser scanning microscopy (CLSM) is presented. It relies on fluorescence intensity distribution to analyze the molecular occurrence statistics captured by digital imaging and enables direct determination of the number of fluorescent molecules and their diffusion rates without resorting to temporal or spatial autocorrelation analyses. Digital images of fluorescent molecules were recorded by using fast scanning and avalanche photodiode detectors. In this way the signal-to-background ratio was significantly improved, enabling direct quantitative imaging by CLSM. The potential of the proposed approach is demonstrated by using standard solutions of fluorescent dyes, fluorescently labeled DNA molecules, quantum dots, and the Enhanced Green Fluorescent Protein in solution and in live cells. The method was verified by using fluorescence correlation spectroscopy. The relevance for biological applications, in particular, for live cell imaging, is discussed.

  12. Theory of the laser diode interaction in scanning force microscopy

    SciTech Connect

    Sarid, D.; Iams, D.A.; Ingle, J.T.; Weissenberger, V.

    1989-08-01

    The theory of interaction of a vibrating cantilever and a laser diode used in a scanning force microscope is given in terms of a feedback-dependent parameter C, which determines the gain associated with this interaction. It is shown that both C and the amplitude of vibrations can be determined experimentally from the measurement of the first and second harmonics. Experimental results, which are in good agreement with the theory, yield a value for C which is 0.045. Under these weak feedback conditions, it is found that the interaction can be modeled approximately as a simple homodyne process.

  13. Scanning laser reflectometry of retinal and subretinal tissues

    NASA Astrophysics Data System (ADS)

    Elsner, Ann E.; Moraes, L.; Beausencourt, E.; Remky, Andreas; Weiter, J. J.; Walker, J. P.; Wing, G. L.; Burns, Stephen Allan; Raskauskas, P. A.; Kelley, L. M.

    2000-06-01

    Measurements of the human ocular fundus that make use of the light returning through the pupil are called reflectometry. Early reflectometry studies were limited by poor light return from the retina and strong reflections from the anterior surface of the eye. Artifacts produced misleading results in diseases like age-related macular degeneration. Novel laser sources, scanning, confocal optics, and digital imaging provide improved sampling of the signal from the tissues of interest: photoreceptors and retinal pigment epithelial cells. A wider range of wavelengths is now compared, including the near infrared. Reflectometry now provides functional mapping, even in severe pathology.

  14. Precision Targeting with a Tracking adaptive Optics Scanning Laser Ophthalmoscope

    DTIC Science & Technology

    2006-02-01

    in Figure 2) but drives two galvanometers placed at appropriate conjugates within the path of the adaptive optics scanning laser ophthalmoscope...reflectometer. The input to the "slave" control loop is the scaled position signals from the master galvanometers . The slave tracking mirrors are placed at...signals and drive galvanometers . The DSP has a loop rate of 62.5 kHz (compared to 16 kHz in the previously-used real-time processing board) for a

  15. [Application of confocal laser scanning microscope in forensic pathology].

    PubMed

    Zhuo, Luo; Hu, Le-Sheng; Zhou, Lan; Zheng, Na; Liang, Man; Yang, Fan; Liu, Liang

    2009-12-01

    Confocal laser scanning microscopy(CLSM) is a new technique for microscopic imaging, which can collect the transverse section image of the samples and produce three-dimensional reconstruction and present higher spatial resolution than the conventional light microscope. As a precision instrument for the microscopic image, it plays an important role in forensic pathology. The article reviews the recent research achievements from sudden cardiac death, bullet wound and nervous system damage, etc, and explores the potential applications of the forensic pathology research and forensic practice.

  16. Automatic road edge detection from Mobile Laser Scanning (MLS)

    NASA Astrophysics Data System (ADS)

    Cabo, Carlos; García-Cortés, Silverio; Menéndez-Díaz, Agustín.; Ordoñez, Celestino

    2016-11-01

    In this article we present an algorithm for automatic road edge detection from MLS (Mobile Laser Scanning) data. The method takes advantage of linear structures derived from MLS point clouds. These lines are extracted from the point cloud and grouped following geometric restrictions. Then, the outlines of the groups are extracted as road edges. Finally, a moving window filter is applied to those points in order to remove outliers and delineate the road edge. The method was tested on an 800m stretch of road, and the results were checked through visual inspection. Correctness and completeness were 99.1% and 97.5%, respectively.

  17. Coastal Benthic Optical Properties Fluorescence Imaging Laser Line Scan Sensor

    DTIC Science & Technology

    2002-09-30

    Coral reefs are a prime example of an environment where current acoustic methods can be expected to have great difficulty. Our prototype Fluorescence Imaging Laser Line Scan (FILLS) sensor[1,2,3,4] has demonstrated that fluorescence imagery provides strong signatures which may be used to separate the coral clutter from mines. The image above demonstrates the ease with which a human observer can differentiate the mine like objects (MLOs) from the natural clutter in an environment that is difficult for sonars. Accordingly, this technology is a leading

  18. Marking of organic materials by CO2 laser beam scanning

    NASA Astrophysics Data System (ADS)

    Dumitras, Dan C.; Chitu, Livia; Blanaru, Constantin; Cernat, Ramona C.; Bucatica, Irina Alexandra L.; Puiu, Adriana P.

    2003-11-01

    CO2 laser beam scanning method was used for marking of organic materials (leather, paper, wood) both in continuous wave and in pulsed regime. The computer controlled X-Y galvometric scanner and the software developed for this application control every parameter of irradiation and allow programmable marking of simple marks, logos, alphanumeric characters, filled text, codes, graphics, or highly complex drawings and images. The factors influencing the quality of the marking were analyzed and the irradiation conditions were optimized to produce marks on organic materials with a quality imposed by industry standards.

  19. Assessment of relative accuracy of AHN-2 laser scanning data using planar features.

    PubMed

    van der Sande, Corné; Soudarissanane, Sylvie; Khoshelham, Kourosh

    2010-01-01

    AHN-2 is the second part of the Actueel Hoogtebestand Nederland project, which concerns the acquisition of high-resolution altimetry data over the entire Netherlands using airborne laser scanning. The accuracy assessment of laser altimetry data usually relies on comparing corresponding tie elements, often points or lines, in the overlapping strips. This paper proposes a new approach to strip adjustment and accuracy assessment of AHN-2 data by using planar features. In the proposed approach a transformation is estimated between two overlapping strips by minimizing the distances between points in one strip and their corresponding planes in the other. The planes and the corresponding points are extracted in an automated segmentation process. The point-to-plane distances are used as observables in an estimation model, whereby the parameters of a transformation between the two strips and their associated quality measures are estimated. We demonstrate the performance of the method for the accuracy assessment of the AHN-2 dataset over Zeeland province of The Netherlands. The results show vertical offsets of up to 4 cm between the overlapping strips, and horizontal offsets ranging from 2 cm to 34 cm.

  20. A Multiple Resource Inventory of Delaware Using an Airborne Profiling Laser

    NASA Technical Reports Server (NTRS)

    Nelson, Ross; Short, Austin; Valenti, Michael A.; Keller, Cherry; Smith, David E. (Technical Monitor)

    2002-01-01

    An airborne profiling laser is used to monitor multiple resources related to landscape structure, both natural and man-made, across regions encompassing hundreds of thousands of hectares. A small, lightweight, inexpensive airborne profiling laser is used to inventory Delaware forests, to estimate impervious surface area statewide, and to locate potentially Suitable Delmarva Fox Squirrel (Scrotum niger cinereus) habitat. Merchantable volume estimates are within 14% of US Forest Service estimates at the county level and within 4% statewide. Total above-ground dry biomass estimates are within 19% of USES estimates at the county level and within 16% statewide. Mature forest stands suitable for reintroduction of the Delmarva Fox Squirrel, an endangered species historically endemic to the eastern shores of Delaware, Maryland, and Virginia, are identified and mapped along the laser transacts. Intersection lengths with various types of impervious surface (roofs, concrete/asphalt) and open water are tallied to estimate percent and areal coverage statewide, by stratum and county. Laser estimates of open water are within 7% of photointerpreted GIS estimates at the county level and within 3% of the GIS at the state level.

  1. Detection and Classification of Individual Airborne Microparticles using Laser Ablation Mass Spectroscopy and Multivariate Analysis

    SciTech Connect

    Gieray, R.A.; Lazar, A.; Parker, E.P.; Ramsey, J. M.; Reilly, P.T.A.; Rosenthal, S.E.; Trahan, M.W.; Wagner, J.S.; Whitten, W.B.

    1999-04-27

    We are developing a method for the real-time analysis of airborne microparticles based on laser ablation mass spectroscopy. Airborne particles enter an ion trap mass spectrometer through a differentially-pumped inlet, are detected by light scattered from two CW laser beams, and sampled by a 10 ns excimer laser pulse at 308 nm as they pass through the center of the ion trap electrodes. After the laser pulse, the stored ions are separated by conventional ion trap methods. In this work thousands of positive and negative ion spectra were collected for eighteen different species: six bacteria, six pollen, and six particulate samples. The data were then averaged and analyzed using the Multivariate Patch Algorithm (MPA), a variant of traditional multivariate anal ysis. The MPA correctly identified all of the positive ion spectra and 17 of the 18 negative ion spectra. In addition, when the average positive and negative spectra were combined the MPA correctly identified all 18 species. Finally, the MPA is also able to identify the components of computer synthesized mixtures of the samples studied

  2. Spectrometers for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR): Airborne Concepts and Ground Prototype Measurements

    NASA Astrophysics Data System (ADS)

    Russell, P. B.; Schmid, B.; Flynn, C.; Dunagan, S. E.; Johnson, R. R.; Redemann, J.; Livingston, J.

    2007-12-01

    A collaboration between NASA Ames Research Center and Battelle Pacific Northwest Division is exploring new instrument concepts that combine sky scanning and spectroscopy with the direct sun transmission measurement capabilities of previous instruments like the NASA Ames Airborne Tracking Sunphotometers (AATS). Additional technical goals are to reduce instrument size, weight, and power requirements while increasing autonomy, so as to permit operation on a wider range of aircraft, including unmanned aerial vehicles (UAVs). The overall science goal for the new instruments is to improve knowledge of atmospheric constituents and their links to climate using a variety of airborne measurement approaches including satellite validation. The sky scanning capability will enable retrievals of aerosol type (via complex refractive index and shape) and aerosol size distribution extending to larger sizes than attainable by direct-beam sunphotometry alone. The spectroscopic capability will improve measurements of gas constituents (e.g., H2O, O3, NO2, SO2) . Concepts explored to date for an airborne Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR-Air) include using fiber optics to link a spectrometer inside the aircraft to optical entrance ports in a relatively small tracking/scanning head outside the aircraft. 4STAR feasibility depends on overcoming three technological hurdles: 1. Maintaining calibration to 1% stability over a period of months. 2. Demonstrating stray light rejection to permit measuring skylight within a few degrees of the sun. 3. Devising a fiber optic coupling that maintains 1% calibration stability with as many as possible of the following desirable characteristics: detachable during assembly before calibration; detachable between calibration and scientific measurements; rotatable during measurements. To investigate ways to overcome these hurdles we have developed a ground-based prototype, 4STAR-Ground. To date 4STAR-Ground has been

  3. Antecedents of two-photon excitation laser scanning microscopy.

    PubMed

    Masters, Barry R; So, Peter T C

    2004-01-01

    In 1931, Maria Göppert-Mayer published her doctoral dissertation on the theory of two-photon quantum transitions (two-photon absorption and emission) in atoms. This report describes and analyzes the theoretical and experimental work on nonlinear optics, in particular two-photon excitation processes, that occurred between 1931 and the experimental implementation of two-photon excitation microscopy by the group of Webb in 1990. In addition to Maria Göppert-Mayer's theoretical work, the invention of the laser has a key role in the development of two-photon microscopy. Nonlinear effects were previously observed in different frequency domains (low-frequency electric and magnetic fields and magnetization), but the high electric field strength afforded by lasers was necessary to demonstrate many nonlinear effects in the optical frequency range. In 1978, the first high-resolution nonlinear microscope with depth resolution was described by the Oxford group. Sheppard and Kompfner published a study in Applied Optics describing microscopic imaging based on second-harmonic generation. In their report, they further proposed that other nonlinear optical effects, such as two-photon fluorescence, could also be applied. However, the developments in the field of nonlinear optical stalled due to a lack of a suitable laser source. This obstacle was removed with the advent of femtosecond lasers in the 1980s. In 1990, the seminal study of Denk, Strickler, and Webb on two-photon laser scanning fluorescence microscopy was published in Science. Their paper clearly demonstrated the capability of two-photon excitation microscopy for biology, and it served to convince a wide audience of scientists of the potential capability of the technique.

  4. Enhanced detection of water and ground surface in airborne laser bathymetry data using waveform stacking

    NASA Astrophysics Data System (ADS)

    Roncat, Andreas; Mandlburger, Gottfried

    2016-04-01

    The past years have seen an increasing scientific interest in high-resolution topographic data of fluvial geomorphology. Moreover, from an administrative perspective, the European Union's water framework directive and the flood directive formulate further requirements on monitoring fluvial landscapes. For capturing the geomorphology of shallow water bodies, e.g. creeks and rivers, airborne laser bathymetry (ALB) has become a method of choice. These instruments operate in the green wavelength domain, enabling for the laser to penetrate the water column. As the water surface is the boundary between two media, i.e. between air and water, and from a physical perspective represents the locus where the laser beam is bent and decelerated. Therefore, the detection of this boundary is crucial for retrieving the channel morphology correctly. However, in case of low signal-to-noise ratio (SNR) these detection may fail for single laser shots. This gives the motivation for increasing the SNR by simulating a bigger laser footprint by means of stacking adjacent laser waveforms in a spatial neighbourhood, e.g. a slanted cylinder. On the one hand, this implies a reduction in spatial resolution; on the other hand though, it means an increase in reliability of the results, both in the detection of the water surface and enabling for assessing the turbidity of water column. The presented approach is evaluated by means of a multi-temporal airbone laser bathymetry dataset captured over the river Pielach and neigbhouring standing water bodies in Loosdorf, Lower Austria.

  5. Determination of foveal location using scanning laser polarimetry

    PubMed Central

    VanNasdale, Dean A.; Elsner, Ann E.; Weber, Anke; Miura, Masahiro; Haggerty, Bryan P.

    2009-01-01

    The fovea is the retinal location responsible for our most acute vision. There are several methods used to localize the fovea, but the fovea is not always easily identifiable. Landmarks used to determine the foveal location are variable in normal subjects and localization becomes even more difficult in instances of retinal disease. In normal subjects, the photoreceptor axons that make up the Henle fiber layer are cylindrical and the radial orientation of these fibers is centered on the fovea. The Henle fiber layer exhibits form birefringence, which predictably changes polarized light in scanning laser polarimetry imaging. In this study 3 graders were able to repeatably identify the fovea in 35 normal subjects using near infrared image types with differing polarization content. There was little intra-grader, inter-grader, and inter-image variability in the graded foveal position for 5 of the 6 image types examined, with accuracy sufficient for clinical purposes. This study demonstrates that scanning laser polarimetry imaging can localize the fovea by using structural properties inherent in the central macula. PMID:19757960

  6. Ligand-Receptor Binding Measured by Laser-Scanning Imaging

    NASA Astrophysics Data System (ADS)

    Zuck, Paul; Lao, Zhege; Skwish, Stephen; Fraser Glickman, J.; Yang, Ke; Burbaum, Jonathan; Inglese, James

    1999-09-01

    This report describes the integration of laser-scanning fluorometric cytometry and nonseparation ligand-binding techniques to provide new assay methods adaptable to miniaturization and high-throughput screening. Receptor-bound, cyanine dye-labeled ligands, [Cy]ligands, were discriminated from those free in solution by measuring the accumulated fluorescence associated with a receptor-containing particle. To illustrate the various binding formats accommodated by this technique, saturation- and competition-binding analyses were performed with [Cy]ligands and their cognate receptors expressed in CHO cells or as fusion proteins coated on polystyrene microspheres. We have successfully applied this technique to the analysis of G protein-coupled receptors, cytokine receptors, and SH2 domains. Multiparameter readouts from ligands labeled separately with Cy5 and Cy5.5 demonstrate the simultaneous analysis of two target receptors in a single well. In addition, laser-scanning cytometry has been used to assay enzymes such as phosphatases and in the development of single-step fluorescent immunoassays.

  7. Adaptive optics scanning laser ophthalmoscope imaging: technology update

    PubMed Central

    Merino, David; Loza-Alvarez, Pablo

    2016-01-01

    Adaptive optics (AO) retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it. PMID:27175057

  8. An omnidirectional 3D sensor with line laser scanning

    NASA Astrophysics Data System (ADS)

    Xu, Jing; Gao, Bingtuan; Liu, Chuande; Wang, Peng; Gao, Shuanglei

    2016-09-01

    An active omnidirectional vision owns the advantages of the wide field of view (FOV) imaging, resulting in an entire 3D environment scene, which is promising in the field of robot navigation. However, the existing omnidirectional vision sensors based on line laser can measure points only located on the optical plane of the line laser beam, resulting in the low-resolution reconstruction. Whereas, to improve resolution, some other omnidirectional vision sensors with the capability of projecting 2D encode pattern from projector and curved mirror. However, the astigmatism property of curve mirror causes the low-accuracy reconstruction. To solve the above problems, a rotating polygon scanning mirror is used to scan the object in the vertical direction so that an entire profile of the observed scene can be obtained at high accuracy, without of astigmatism phenomenon. Then, the proposed method is calibrated by a conventional 2D checkerboard plate. The experimental results show that the measurement error of the 3D omnidirectional sensor is approximately 1 mm. Moreover, the reconstruction of objects with different shapes based on the developed sensor is also verified.

  9. Determination of Percent Body Fat Using 3D Whole Body Laser Scanning: A Preliminary Investigation

    DTIC Science & Technology

    2006-11-01

    circumferences, 3D whole body laser scans and DEXA scans were performed on fifty-one men and women age 18-62. Mean percent body fat was not statistically...3D whole body laser scan , and DEXA scan to measure individuals during a one hour measurement session. 1 Report Documentation Page Form...underwent a 6 minute whole body DEXA scan using a GE Lunar Prodigy DEXA scanner running software version 7.53. Percent body fat was calculated from the

  10. Development of a laser fluorosensor for airborne surveying of the aquatic environment

    NASA Technical Reports Server (NTRS)

    Bristow, M. P. F.; Houston, W. R.; Measures, R. M.

    1975-01-01

    A field based laser fluorosensor, employing a pulsed nitrogen laser and telescope photomultiplier detector system, has been successfully tested at night from a cliff top site overlooking Lake Ontario providing target ranges greater than 274 meters. Remotely sensed spectra and amplitude changes in the fluorescence emission of natural waters have shown potential as a water quality indicator. In this connection, a convenient internal reference standard with which to gauge the amplitude of the fluorescence signal is realized in the form of the concurrent water Raman emission. Remote measurements of oil fluorescence emission spectra suggest that airborne laser fluorosensors are capable of detecting and characterizing the oil in a given slick and that environmental aging of these slicks does not significantly alter their fluorescence emission signature.

  11. Quantification of telomere length by FISH and laser scanning cytometry

    NASA Astrophysics Data System (ADS)

    Mahoney, John E.; Sahin, Ergun; Jaskelioff, Mariela; Chin, Lynda; DePinho, Ronald A.; Protopopov, Alexei I.

    2008-02-01

    Telomeres play a critical role in the maintenance of chromosomal stability. Telomere erosion, coupled with loss of DNA damage checkpoint function, results in genomic instability that promotes the development of cancer. The critical role of telomere dynamics in cancer has motivated the development of technologies designed to monitor telomere reserves in a highly quantitative and high-throughput manner in humans and model organisms. To this end, we have adapted and modified two established technologies, telomere-FISH and laser scanning cytometry. Specifically, we have produced a number of enhancements to the iCys LSC (CompuCyte) package including software updates, use of 60X dry objectives, and increased spatial resolution by 0.2 um size of stage steps. In addition, the 633 nm HeNe laser was replaced with a 532 nm green diode laser to better match the viewing options. Utilization of telomere-deficient mouse cells with short dysfunctional telomeres and matched telomerase reconstituted cultures demonstrated significantly higher mean integral specific fluorescence values for mTR transfectants relative to empty vector controls: 4.485M vs. 1.362M (p<0.0001). Histograms of average telomere intensities for individual cells were obtained and demonstrated intercellular heterogeneity in telomere lengths. The validation of the approach derives from a strong correlation between iCys LSC values and Southern blotting. This validated method greatly increases our experimental throughput and objectivity.

  12. Automated laser registration in image-guided surgery: evaluation of the correlation between laser scan resolution and navigation accuracy.

    PubMed

    Marmulla, R; Lüth, T; Mühling, J; Hassfeld, S

    2004-10-01

    Markerless patient registration based on the facial skin surface makes logistics prior to image-guided surgery much easier, as it is not necessary to place and measure registration markers. A laser scan registration of the surgical site takes the place of conventional marker-based registration. In a clinical study, the stability and accuracy of markerless patient registration was evaluated in 12 patients. Intraoral titanium markers served as targets for the infrared-pointer of the navigation system in order to check the accuracy of the markerless registration process. The correlation between laser scan resolution and navigation accuracy was checked using seven different laser scan resolutions (a cloud of 300,000 laser scan points down to 3750 laser scan points of the surgical site). The markerless patient registration was successful as long as high laser scan resolution was used (30,000 laser scan points and more): the titanium markers were detected with a mean deviation of 1.1 +/- 0.2 mm. Low resolution laser scans (6000 laser scan points of the surgical site and less) revealed inaccuracies up to 6 mm.

  13. Motion-compensated blind deconvolution of scanning laser opthalmoscope imagery

    NASA Astrophysics Data System (ADS)

    O'Connor, Nathan J.; Bartsch, Dirk-Uwe G.; Freeman, William R.; Holmes, Timothy J.

    1998-06-01

    A deconvolution algorithm for use with scanning laser ophthalmoscope (SLO) data is being developed. The SLO is fundamentally a confocal microscope in which the objective lens is the human ocular lens. 3D data is collected by raster scanning to form images at different depths in retinal and choroidal layers. In this way, 3D anatomy may be imaged and stored as a series of optical sections.Given the poor optical quality of the human lens and random eye motion during data acquisition, any deconvolution method applied to SLO data must be able to account for distortions present in the observed data. The algorithm presented compensates for image warping and frame-to-frame displacement due to random eye motion, smearing along the optic axis, sensor saturation, and other problems. A preprocessing step is first used to compensate for frame-to-frame image displacement. The image warping, caused by random eye motion during raster scanning, is corrected. Finally, a maximum likelihood based blind deconvolution algorithm is used to correct severe blurring along the optic axis. The blind deconvolution algorithm contains an iterative search for subpixel displacements remaining after image warping and frame-to-frame displacements are corrected. This iterative search is formulated to ensure that the likelihood functional is non-decreasing.

  14. Pavement cracking measurements using 3D laser-scan images

    NASA Astrophysics Data System (ADS)

    Ouyang, W.; Xu, B.

    2013-10-01

    Pavement condition surveying is vital for pavement maintenance programs that ensure ride quality and traffic safety. This paper first introduces an automated pavement inspection system which uses a three-dimensional (3D) camera and a structured laser light to acquire dense transverse profiles of a pavement lane surface when it carries a moving vehicle. After the calibration, the 3D system can yield a depth resolution of 0.5 mm and a transverse resolution of 1.56 mm pixel-1 at 1.4 m camera height from the ground. The scanning rate of the camera can be set to its maximum at 5000 lines s-1, allowing the density of scanned profiles to vary with the vehicle's speed. The paper then illustrates the algorithms that utilize 3D information to detect pavement distress, such as transverse, longitudinal and alligator cracking, and presents the field tests on the system's repeatability when scanning a sample pavement in multiple runs at the same vehicle speed, at different vehicle speeds and under different weather conditions. The results show that this dedicated 3D system can capture accurate pavement images that detail surface distress, and obtain consistent crack measurements in repeated tests and under different driving and lighting conditions.

  15. Street environment change detection from mobile laser scanning point clouds

    NASA Astrophysics Data System (ADS)

    Xiao, Wen; Vallet, Bruno; Brédif, Mathieu; Paparoditis, Nicolas

    2015-09-01

    Mobile laser scanning (MLS) has become a popular technique for road inventory, building modelling, infrastructure management, mobility assessment, etc. Meanwhile, due to the high mobility of MLS systems, it is easy to revisit interested areas. However, change detection using MLS data of street environment has seldom been studied. In this paper, an approach that combines occupancy grids and a distance-based method for change detection from MLS point clouds is proposed. Unlike conventional occupancy grids, our occupancy-based method models space based on scanning rays and local point distributions in 3D without voxelization. A local cylindrical reference frame is presented for the interpolation of occupancy between rays according to the scanning geometry. The Dempster-Shafer theory (DST) is utilized for both intra-data evidence fusion and inter-data consistency assessment. Occupancy of reference point cloud is fused at the location of target points and then the consistency is evaluated directly on the points. A point-to-triangle (PTT) distance-based method is combined to improve the occupancy-based method. Because it is robust to penetrable objects, e.g. vegetation, which cause self-conflicts when modelling occupancy. The combined method tackles irregular point density and occlusion problems, also eliminates false detections on penetrable objects.

  16. Airborne laser induced fluorescence imaging. Innovative technology summary report

    SciTech Connect

    1999-06-01

    Laser-Induced Fluorescence (LIF) was demonstration as part of the Fernald Environmental Management Project (FEMP) Plant 1 Large Scale Demonstration and Deployment Project (LSDDP) sponsored by the US Department of Energy (DOE) Office of Science and Technology, Deactivation and Decommissioning Focus Area located at the Federal Energy Technology Center (FETC) in Morgantown, West Virginia. The demonstration took place on November 19, 1996. In order to allow the contaminated buildings undergoing deactivation and decommissioning (D and D) to be opened to the atmosphere, radiological surveys of floors, walls and ceilings must take place. After successful completion of the radiological clearance survey, demolition of the building can continue. Currently, this process is performed by collecting and analyzing swipe samples for radiological analysis. Two methods are used to analyze the swipe samples: hand-held frisker and laboratory analysis. For the purpose of this demonstration, the least expensive method, swipe samples analyzed by hand-held frisker, is the baseline technology. The objective of the technology demonstration was to determine if the baseline technology could be replaced using LIF.

  17. The airborne Laser Absorption Spectrometer - A new instrument of remote measurement of atmospheric trace gases

    NASA Technical Reports Server (NTRS)

    Shumate, M. S.; Menzies, R. T.

    1978-01-01

    The Laser Absorption Spectrometer is a portable instrument developed by JPL for remote measurement of trace gases from an aircraft platform. It contains two carbon dioxide lasers, two optical heterodyne receivers, appropriate optics to aim the lasers at the ground and detect the backscattered energy, and signal processing and recording electronics. Operating in the differential-absorption mode, it is possible to monitor one atmospheric gas at a time and record the data in real time. The system can presently measure ozone, ethylene, water vapor, and chlorofluoromethanes with high sensitivity. Airborne measurements were made in early 1977 from the NASA/JPL twin-engine Beechcraft and in May 1977 from the NASA Convair 990 during the ASSESS-II Shuttle Simulation Study. These flights resulted in measurements of ozone concentrations in the lower troposphere which were compared with ground-based values provided by the Air Pollution Control District. This paper describes the details of the instrument and results of the airborne measurements.

  18. Assessment of NASA airborne laser altimetry data using ground-based GPS data near Summit Station, Greenland

    NASA Astrophysics Data System (ADS)

    Brunt, Kelly M.; Hawley, Robert L.; Lutz, Eric R.; Studinger, Michael; Sonntag, John G.; Hofton, Michelle A.; Andrews, Lauren C.; Neumann, Thomas A.

    2017-03-01

    A series of NASA airborne lidars have been used in support of satellite laser altimetry missions. These airborne laser altimeters have been deployed for satellite instrument development, for spaceborne data validation, and to bridge the data gap between satellite missions. We used data from ground-based Global Positioning System (GPS) surveys of an 11 km long track near Summit Station, Greenland, to assess the surface-elevation bias and measurement precision of three airborne laser altimeters including the Airborne Topographic Mapper (ATM), the Land, Vegetation, and Ice Sensor (LVIS), and the Multiple Altimeter Beam Experimental Lidar (MABEL). Ground-based GPS data from the monthly ground-based traverses, which commenced in 2006, allowed for the assessment of nine airborne lidar surveys associated with ATM and LVIS between 2007 and 2016. Surface-elevation biases for these altimeters - over the flat, ice-sheet interior - are less than 0.12 m, while assessments of measurement precision are 0.09 m or better. Ground-based GPS positions determined both with and without differential post-processing techniques provided internally consistent solutions. Results from the analyses of ground-based and airborne data provide validation strategy guidance for the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) elevation and elevation-change data products.

  19. Airborne laser quantification of Florida shoreline and beach volume change caused by hurricanes

    NASA Astrophysics Data System (ADS)

    Robertson, William, V.

    This dissertation combines three separate studies that measure coastal change using airborne laser data. The initial study develops a method for measuring subaerial and subaqueous volume change incrementally alongshore, and compares those measurements to shoreline change in order to quantify their relationship in Palm Beach County, Florida. A poor correlation (R2 = 0.39) was found between shoreline and volume change before the hurricane season in the northern section of Palm Beach County because of beach nourishment and inlet dynamics. However, a relatively high R2 value of 0.78 in the southern section of Palm Beach County was found due to little disturbance from tidal inlets and coastal engineering projects. The shoreline and volume change caused by the 2004 hurricane season was poorly correlated with R 2 values of 0.02 and 0.42 for the north and south sections, respectively. The second study uses airborne laser data to investigate if there is a significant relationship between shoreline migration before and after Hurricane Ivan near Panama City, Florida. In addition, the relationship between shoreline change and subaerial volume was quantified and a new method for quantifying subaqueous sediment change was developed. No significant spatial relationship was found between shoreline migration before and after the hurricane. Utilization of a single coefficient to represent all relationships between shoreline and subaerial volume change was found to be problematic due to the spatial variability in the linear relationship. Differences in bathymetric data show only a small portion of sediment was transported beyond the active zone and most sediment remained within the active zone despite the occurrence of a hurricane. The third study uses airborne laser bathymetry to measure the offshore limit of change, and compares that location with calculated depth of closures and subaqueous geomorphology. There appears to be strong geologic control of the depth of closure in

  20. Comparison of Retracking Algorithms Using Airborne Radar and Laser Altimeter Measurements of the Greenland Ice Sheet

    NASA Technical Reports Server (NTRS)

    Ferraro, Ellen J.; Swift, Calvin T.

    1995-01-01

    This paper compares four continental ice sheet radar altimeter retracking algorithms using airborne radar and laser altimeter data taken over the Greenland ice sheet in 1991. The refurbished Advanced Application Flight Experiment (AAFE) airborne radar altimeter has a large range window and stores the entire return waveform during flight. Once the return waveforms are retracked, or post-processed to obtain the most accurate altitude measurement possible, they are compared with the high-precision Airborne Oceanographic Lidar (AOL) altimeter measurements. The AAFE waveforms show evidence of varying degrees of both surface and volume scattering from different regions of the Greenland ice sheet. The AOL laser altimeter, however, obtains a return only from the surface of the ice sheet. Retracking altimeter waveforms with a surface scattering model results in a good correlation with the laser measurements in the wet and dry-snow zones, but in the percolation region of the ice sheet, the deviation between the two data sets is large due to the effects of subsurface and volume scattering. The Martin et al model results in a lower bias than the surface scattering model, but still shows an increase in the noise level in the percolation zone. Using an Offset Center of Gravity algorithm to retrack altimeter waveforms results in measurements that are only slightly affected by subsurface and volume scattering and, despite a higher bias, this algorithm works well in all regions of the ice sheet. A cubic spline provides retracked altitudes that agree with AOL measurements over all regions of Greenland. This method is not sensitive to changes in the scattering mechanisms of the ice sheet and it has the lowest noise level and bias of all the retracking methods presented.

  1. An airborne laser fluorosensor for the detection of oil on water

    NASA Technical Reports Server (NTRS)

    Kim, H. H.; Hickman, G. D.

    1975-01-01

    An airborne laser fluorosensor for the detection of oil derivatives on water has been tested. The system transmits 337 nm UV radiation at the rate of 100 pulses per second and monitors fluorescent emission at 540 nm. Daylight flight tests were made over the areas of controlled oil spills and additional reconnaissance flights were made over a 50 km stretch of the Delaware River to establish ambient oil baseline in the river. The results show that the device is capable of monitoring and mapping out extremely low level oil on water which cannot be identified by ordinary photographic method.

  2. Development and Utilization of High Precision Digital Elevation Data taken by Airborne Laser Scanner

    NASA Astrophysics Data System (ADS)

    Akutsu, Osamu; Ohta, Masataka; Isobe, Tamio; Ando, Hisamitsu, Noguchi, Takahiro; Shimizu, Masayuki

    2005-03-01

    Disasters caused by heavy rain in urban areas bring a damage such as chaos in the road and railway transport systems, power failure, breakdown of the telephone system and submersion of built up areas, subways and underground shopping arcades, etc. It is important to obtain high precision elevation data which shows the detailed landform because a slight height difference affects damages by flood very considerably. Therefore, The Geographical Survey Institute (GSI) is preparing 5m grid digital terrain model (DTM) based on precise ground elevation data taken by using airborne laser scanner. This paper describes the process and an example of the use of a 5m grid digital data set.

  3. Classification of vegetation in an open landscape using full-waveform airborne laser scanner data

    NASA Astrophysics Data System (ADS)

    Alexander, Cici; Deák, Balázs; Kania, Adam; Mücke, Werner; Heilmeier, Hermann

    2015-09-01

    Airborne laser scanning (ALS) is increasingly being used for the mapping of vegetation, although the focus so far has been on woody vegetation, and ALS data have only rarely been used for the classification of grassland vegetation. In this study, we classified the vegetation of an open alkali landscape, characterized by two Natura 2000 habitat types: Pannonic salt steppes and salt marshes and Pannonic loess steppic grasslands. We generated 18 variables from an ALS dataset collected in the growing (leaf-on) season. Elevation is a key factor determining the patterns of vegetation types in the landscape, and hence 3 additional variables were based on a digital terrain model (DTM) generated from an ALS dataset collected in the dormant (leaf-off) season. We classified the vegetation into 24 classes based on these 21 variables, at a pixel size of 1 m. Two groups of variables with and without the DTM-based variables were used in a Random Forest classifier, to estimate the influence of elevation, on the accuracy of the classification. The resulting classes at Level 4, based on associations, were aggregated at three levels - Level 3 (11 classes), Level 2 (8 classes) and Level 1 (5 classes) - based on species pool, site conditions and structure, and the accuracies were assessed. The classes were also aggregated based on Natura 2000 habitat types to assess the accuracy of the classification, and its usefulness for the monitoring of habitat quality. The vegetation could be classified into dry grasslands, wetlands, weeds, woody species and man-made features, at Level 1, with an accuracy of 0.79 (Cohen's kappa coefficient, κ). The accuracies at Levels 2-4 and the classification based on the Natura 2000 habitat types were κ: 0.76, 0.61, 0.51 and 0.69, respectively. Levels 1 and 2 provide suitable information for nature conservationists and land managers, while Levels 3 and 4 are especially useful for ecologists, geologists and soil scientists as they provide high resolution

  4. Airborne megawatt class free-electron laser for defense and security

    SciTech Connect

    Roy Whitney; David Douglas; George Neil

    2005-03-01

    An airborne megawatt (MW) average power Free-Electron Laser (FEL) is now a possibility. In the process of shrinking the FEL parameters to fit on ship, a surprisingly lightweight and compact design has been achieved. There are multiple motivations for using a FEL for a high-power airborne system for Defense and Security: Diverse mission requirements can be met by a single system. The MW of light can be made available with any time structure for time periods from microseconds to hours, i.e. there is a nearly unlimited magazine. The wavelength of the light can be chosen to be from the far infrared (IR) to the near ultraviolet (UV) thereby best meeting mission requirements. The FEL light can be modulated for detecting the same pattern in the small fraction of light reflected from the target resulting in greatly enhanced targeting control. The entire MW class FEL including all of its subsystems can be carried by large commercial size airplanes or on an airship. Adequate electrical power can be generated on the plane or airship to run the FEL as long as the plane or airship has fuel to fly. The light from the FEL will work well with relay mirror systems. The required R&D to achieve the MW level is well understood. The coupling of the capabilities of an airborne FEL to diverse mission requirements provides unique opportunities.

  5. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer.

    PubMed

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L; Shung, K Kirk; Zhang, Hao F; Jiao, Shuliang

    2012-11-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging.

  6. Quantitative flaw characterization with scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.; Roth, D. J.

    1986-01-01

    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. In accuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

  7. Nondestructive monitoring damage in composites using scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Wey, A. C.; Kessler, L. W.; Dos Reis, H. L. M.

    1992-01-01

    Several Nicalon fiber reinforced LAS (lithium alumino-silicate) glass matrix composites were tested to study the relation between the residual strength and the different amounts of damage. The samples were fatigued by four-point cyclic loading at a 5 Hz rate at 500 C for a different number of cycles. 10 MHz scanning laser acoustic microscope (SLAM) images were taken to monitor damage on the samples. Our SLAM results indicate that there were defects already existing throughout the sample before fatigue, and the resultant damage pattern from fatigue could be related to the initial defect distribution in the sample. Finally, the fatigued samples were fractured and the residual strength data could not be explained by the cyclic fatigue alone. Rather, the damage patterns evident in the SLAM images were needed to explain the scatter in the data. The results show that SLAM is useful in nondestructively monitoring damage and estimating residual strength of fatigued ceramic composites.

  8. Adaptive optics for confocal laser scanning microscopy with adjustable pinhole

    NASA Astrophysics Data System (ADS)

    Yoo, Han Woong; van Royen, Martin E.; van Cappellen, Wiggert A.; Houtsmuller, Adriaan B.; Verhaegen, Michel; Schitter, Georg

    2016-04-01

    The pinhole plays an important role in confocal laser scanning microscopy (CLSM) for adaptive optics (AO) as well as in imaging, where the size of the pinhole denotes a trade-off between out-of-focus rejection and wavefront distortion. This contribution proposes an AO system for a commercial CLSM with an adjustable square pinhole to cope with such a trade-off. The proposed adjustable pinhole enables to calibrate the AO system and to evaluate the imaging performance. Experimental results with fluorescence beads on the coverslip and at a depth of 40 μm in the human hepatocellular carcinoma cell spheroid demonstrate that the proposed AO system can improve the image quality by the proposed calibration method. The proposed pinhole intensity ratio also indicates the image improvement by the AO correction in intensity as well as resolution.

  9. Laser-scanning photoacoustic microscopy with ultrasonic phased array transducer

    PubMed Central

    Zheng, Fan; Zhang, Xiangyang; Chiu, Chi Tat; Zhou, Bill L.; Shung, K. Kirk; Zhang, Hao F.; Jiao, Shuliang

    2012-01-01

    In this paper, we report our latest progress on proving the concept that ultrasonic phased array can improve the detection sensitivity and field of view (FOV) in laser-scanning photoacoustic microscopy (LS-PAM). A LS-PAM system with a one-dimensional (1D) ultrasonic phased array was built for the experiments. The 1D phased array transducer consists of 64 active elements with an overall active dimension of 3.2 mm × 2 mm. The system was tested on imaging phantom and mouse ear in vivo. Experiments showed a 15 dB increase of the signal-to-noise ratio (SNR) when beamforming was employed compared to the images acquired with each single element. The experimental results demonstrated that ultrasonic phased array can be a better candidate for LS-PAM in high sensitivity applications like ophthalmic imaging. PMID:23162708

  10. Multicomponent wavefield characterization with a novel scanning laser interferometer.

    PubMed

    Blum, Thomas E; van Wijk, Kasper; Pouet, Bruno; Wartelle, Alexis

    2010-07-01

    The in-plane component of the wavefield provides valuable information about media properties from seismology to nondestructive testing. A new compact scanning laser ultrasonic interferometer collects light scattered away from the angle of incidence to provide the absolute ultrasonic displacement for both the out-of-plane and an in-plane components. This new system is tested by measuring the radial and vertical polarization of a Rayleigh wave in an aluminum half-space. The estimated amplitude ratio of the horizontal and vertical displacement agrees well with the theoretical value. The phase difference exhibits a small bias between the two components due to a slightly different frequency response between the two processing channels of the prototype electronic circuitry.

  11. Multicomponent wavefield characterization with a novel scanning laser interferometer

    SciTech Connect

    Blum, Thomas E.; Wijk, Kasper van; Pouet, Bruno; Wartelle, Alexis

    2010-07-15

    The in-plane component of the wavefield provides valuable information about media properties from seismology to nondestructive testing. A new compact scanning laser ultrasonic interferometer collects light scattered away from the angle of incidence to provide the absolute ultrasonic displacement for both the out-of-plane and an in-plane components. This new system is tested by measuring the radial and vertical polarization of a Rayleigh wave in an aluminum half-space. The estimated amplitude ratio of the horizontal and vertical displacement agrees well with the theoretical value. The phase difference exhibits a small bias between the two components due to a slightly different frequency response between the two processing channels of the prototype electronic circuitry.

  12. Quantitative flaw characterization with scanning laser acoustic microscopy

    SciTech Connect

    Generazio, E.R.; Roth, D.J.

    1986-06-01

    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw. 15 references.

  13. Quantitative flaw characterization with scanning laser acoustic microscopy

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.; Roth, D. J.

    1986-01-01

    Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. The relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness is investigated. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw.

  14. System Design Considerations In Bar-Code Laser Scanning

    NASA Astrophysics Data System (ADS)

    Barkan, Eric; Swartz, Jerome

    1984-08-01

    The unified transfer function approach to the design of laser barcode scanner signal acquisition hardware is considered. The treatment of seemingly disparate system areas such as the optical train, the scanning spot, the electrical filter circuits, the effects of noise, and printing errors is presented using linear systems theory. Such important issues as determination of depth of modulation, filter specification, tolerancing of optical components, and optimi-zation of system performance in the presence of noise are discussed. The concept of effective spot size to allow for impact of optical system and analog processing circuitry upon depth of modulation is introduced. Considerations are limited primarily to Gaussian spot profiles, but also apply to more general cases. Attention is paid to realistic bar-code symbol models and to implications with respect to printing tolerances.

  15. Control electronics for a multi-laser/multi-detector scanning system

    NASA Technical Reports Server (NTRS)

    Kennedy, W.

    1980-01-01

    The Mars Rover Laser Scanning system uses a precision laser pointing mechanism, a photodetector array, and the concept of triangulation to perform three dimensional scene analysis. The system is used for real time terrain sensing and vision. The Multi-Laser/Multi-Detector laser scanning system is controlled by a digital device called the ML/MD controller. A next generation laser scanning system, based on the Level 2 controller, is microprocessor based. The new controller capabilities far exceed those of the ML/MD device. The first draft circuit details and general software structure are presented.

  16. Imaging Single ZnO Vertical Nanowire Laser Cavities using UV-Laser Scanning Confocal Microscopy

    SciTech Connect

    Gargas, D.J.; Toimil-Molares, M.E.; Yang, P.

    2008-11-17

    We report the fabrication and optical characterization of individual ZnO vertical nanowire laser cavities. Dilute nanowire arrays with interwire spacing>10 ?m were produced by a modified chemical vapor transport (CVT) method yielding an ideal platform for single nanowire imaging and spectroscopy. Lasing characteristics of a single vertical nanowire are presented, as well as high-resolution photoluminescence imaging by UV-laser scanning confocal microscopy. In addition, three-dimensional (3D) mapping of the photoluminescence emission performed in both planar and vertical dimensions demonstrates height-selective imaging useful for vertical nanowires and heteronanostructures emerging in the field of optoelectronics and nanophotonics.

  17. High-sensitive scanning laser magneto-optical imaging system.

    PubMed

    Murakami, Hironaru; Tonouchi, Masayoshi

    2010-01-01

    A high-sensitive scanning laser magneto-optical (MO) imaging system has been developed. The system is mainly composed of a laser source, galvano meters, and a high-sensitive differential optical-detector. Preliminary evaluation of system performance by using a Faraday indicator with a Faraday rotation coefficient of 3.47 x 10(-5) rad/microm Oe shows a magnetic sensitivity of about 5 microT, without any need for accumulation or averaging processing. Using the developed MO system we have succeeded in the fast and quantitative imaging of a rotationally symmetric magnetic field distribution around an YBa(2)Cu(3)O(7-delta) (YBCO) strip line applied with dc-biased current, and also succeeded in the detection of quantized fine signals corresponding to magnetic flux quantum generation in a superconducting loop of an YBCO Josephson vortex flow transistor. Thus, the developed system enables us not only to do fast imaging and local signal detection but also to directly evaluate both the strength and direction of a magnetic signal.

  18. A vector scanning processing technique for pulsed laser velocimetry

    NASA Astrophysics Data System (ADS)

    Wernet, Mark P.; Edwards, Robert V.

    1989-03-01

    Pulsed laser sheet velocimetry yields nonintrusive measurements of two-dimensional velocity vectors across an extended planar region of a flow. Current processing techniques offer high precision (1 pct) velocity estimates, but can require several hours of processing time on specialized array processors. Under some circumstances, a simple, fast, less accurate (approx. 5 pct), data reduction technique which also gives unambiguous velocity vector information is acceptable. A direct space domain processing technique was examined. The direct space domain processing technique was found to be far superior to any other techniques known, in achieving the objectives listed above. It employs a new data coding and reduction technique, where the particle time history information is used directly. Further, it has no 180 deg directional ambiguity. A complex convection vortex flow was recorded and completely processed in under 2 minutes on an 80386 based PC, producing a 2-D velocity vector map of the flow field. Hence, using this new space domain vector scanning (VS) technique, pulsed laser velocimetry data can be reduced quickly and reasonably accurately, without specialized array processing hardware.

  19. Systematic Effects in Laser Scanning and Visualization by Confidence Regions

    NASA Astrophysics Data System (ADS)

    Koch, Karl-Rudolf; Brockmann, Jan Martin

    2016-12-01

    A new method for dealing with systematic effects in laser scanning and visualizing them by confidence regions is derived. The standard deviations of the systematic effects are obtained by repeatedly measuring three-dimensional coordinates by the laser scanner. In addition, autocovariance and cross-covariance functions are computed by the repeated measurements and give the correlations of the systematic effects. The normal distribution for the measurements and the multivariate uniform distribution for the systematic effects are applied to generate random variates for the measurements and random variates for the measurements plus systematic effects. Monte Carlo estimates of the expectations and the covariance matrix of the measurements with systematic effects are computed. The densities for the confidence ellipsoid for the measurements and the confidence region for the measurements with systematic effects are obtained by relative frequencies. They only depend on the size of the rectangular volume elements for which the densities are determined. The problem of sorting the densities is solved by sorting distances together with the densities. This allows a visualization of the confidence ellipsoid for the measurements and the confidence region for the measurements with systematic effects.

  20. Pedestrian Detection by Laser Scanning and Depth Imagery

    NASA Astrophysics Data System (ADS)

    Barsi, A.; Lovas, T.; Molnar, B.; Somogyi, A.; Igazvolgyi, Z.

    2016-06-01

    Pedestrian flow is much less regulated and controlled compared to vehicle traffic. Estimating flow parameters would support many safety, security or commercial applications. Current paper discusses a method that enables acquiring information on pedestrian movements without disturbing and changing their motion. Profile laser scanner and depth camera have been applied to capture the geometry of the moving people as time series. Procedures have been developed to derive complex flow parameters, such as count, volume, walking direction and velocity from laser scanned point clouds. Since no images are captured from the faces of pedestrians, no privacy issues raised. The paper includes accuracy analysis of the estimated parameters based on video footage as reference. Due to the dense point clouds, detailed geometry analysis has been conducted to obtain the height and shoulder width of pedestrians and to detect whether luggage has been carried or not. The derived parameters support safety (e.g. detecting critical pedestrian density in mass events), security (e.g. detecting prohibited baggage in endangered areas) and commercial applications (e.g. counting pedestrians at all entrances/exits of a shopping mall).

  1. Airborne Carbon Dioxide Laser Absorption Spectrometer for IPDA Measurements of Tropospheric CO2: Recent Results

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.; Menzies, Robert T.

    2008-01-01

    The National Research Council's decadal survey on Earth Science and Applications from Space[1] recommended the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission for launch in 2013-2016 as a logical follow-on to the Orbiting Carbon Observatory (OCO) which is scheduled for launch in late 2008 [2]. The use of a laser absorption measurement technique provides the required ability to make day and night measurements of CO2 over all latitudes and seasons. As a demonstrator for an approach to meeting the instrument needs for the ASCENDS mission we have developed the airborne Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) which uses the Integrated Path Differential Absorption (IPDA) Spectrometer [3] technique operating in the 2 micron wavelength region.. During 2006 a short engineering checkout flight of the CO2LAS was conducted and the results presented previously [4]. Several short flight campaigns were conducted during 2007 and we report results from these campaigns.

  2. Oil film thickness measurement using airborne laser-induced water Raman backscatter

    NASA Technical Reports Server (NTRS)

    Hoge, F. E.; Swift, R. N.

    1980-01-01

    The use of laser-induced water Raman backscatter for remote thin oil film detection and thickness measurement is reported here for the first time. A 337.1-nm nitrogen laser was used to excite the 3400-cm-1 OH stretch band of natural ocean water beneath the oil slick from an altitude of 150 m. The signal strength of the 381-nm water Raman backscatter was always observed to depress when the oil was encountered and then return to its original undepressed value after complete aircraft traversal of the floating slick. After removal of background and oil fluorescence contributions, the ratio of the depressed-to-undepressed airborne water Raman signal intensities, together with laboratory measured oil extinction coefficients, is used to calculate the oil film thickness.

  3. Quantifying Snow Volume Uncertainty from Repeat Terrestrial Laser Scanning Observations

    NASA Astrophysics Data System (ADS)

    Gadomski, P. J.; Hartzell, P. J.; Finnegan, D. C.; Glennie, C. L.; Deems, J. S.

    2014-12-01

    Terrestrial laser scanning (TLS) systems are capable of providing rapid, high density, 3D topographic measurements of snow surfaces from increasing standoff distances. By differencing snow surface with snow free measurements within a common scene, snow depths and volumes can be estimated. These data can support operational water management decision-making when combined with measured or modeled snow densities to estimate basin water content, evaluate in-situ data, or drive operational hydrologic models. In addition, change maps from differential TLS scans can also be used to support avalanche control operations to quantify loading patterns for both pre-control planning and post-control assessment. However, while methods for computing volume from TLS point cloud data are well documented, a rigorous quantification of the volumetric uncertainty has yet to be presented. Using repeat TLS data collected at the Arapahoe Basin Ski Area in Summit County, Colorado, we demonstrate the propagation of TLS point measurement and cloud registration uncertainties into 3D covariance matrices at the point level. The point covariances are then propagated through a volume computation to arrive at a single volume uncertainty value. Results from two volume computation methods are compared and the influence of data voids produced by occlusions examined.

  4. Geodetic Imaging of Marsh Surface Elevation with Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Nguyen, C. T.; Starek, M. J.; Gibeaut, J. C.; Lord, A.

    2015-12-01

    The resilience of marshes to a rising sea is dependent on their elevation response. Given the level of precision required to measure minute changes in marsh elevation over time, survey methods have to be adapted to minimize impacts to the sediment surface. Current approaches include Surface Elevation Tables (SETs), which are used to monitor wetland surface change with respect to an in situ vertical benchmark. Although SETs have been proven as an effective technique to track subtle sedimentation rates (< 1 cm/year), they provide a single-point measurement construed to a location with limited to no information on the spatial pattern in marsh elevation response away from the measurement site. Terrestrial Laser Scanning (TLS) offers potential for high definition monitoring of marsh surface evolution. However, several challenges must be overcome in the application of the technology for geodetic imaging of marsh surfaces. These challenges include surface occlusion by dense vegetation, error propagation due to scan co-registration and referencing across time, impacts of scan angle, and filtering of non-ground points. Researchers at Texas A&M University-Corpus Christi conducted a field-survey of a marsh within the Grand Bay National Estuarine Research Reserve using TLS and RTK GPS for comparison. Grand Bay in Mississippi USA is one of the most biologically productive estuarine ecosystems in the Gulf of Mexico. The study region is covered by dense and tall saw-grass that makes it a challenging environment for bare-earth mapping. For this survey, a Riegl VZ-400 TLS (1550 nm wavelength) was utilized. The system is capable of recording multiple returns per a transmitted pulse (up to 15) and provides full-waveform output for signal post-processing to extract returns. The objectives of the study are twofold: 1) examine impacts of TLS survey design, scan angle and scan density on marsh elevation mapping; 2) assess the capabilities of multiple-echo and full-waveform TLS data to

  5. Laser scanning cytometry as a tool for biomarker validation

    NASA Astrophysics Data System (ADS)

    Mittag, Anja; Füldner, Christiane; Lehmann, Jörg; Tarnok, Attila

    2013-03-01

    Biomarkers are essential for diagnosis, prognosis, and therapy. As diverse is the range of diseases the broad is the range of biomarkers and the material used for analysis. Whereas body fluids can be relatively easily obtained and analyzed, the investigation of tissue is in most cases more complicated. The same applies for the screening and the evaluation of new biomarkers and the estimation of the binding of biomarkers found in animal models which need to be transferred into applications in humans. The latter in particular is difficult if it recognizes proteins or cells in tissue. A better way to find suitable cellular biomarkers for immunoscintigraphy or PET analyses may be therefore the in situ analysis of the cells in the respective tissue. In this study we present a method for biomarker validation using Laser Scanning Cytometry which allows the emulation of future in vivo analysis. The biomarker validation is exemplarily shown for rheumatoid arthritis (RA) on synovial membrane. Cryosections were scanned and analyzed by phantom contouring. Adequate statistical methods allowed the identification of suitable markers and combinations. The fluorescence analysis of the phantoms allowed the discrimination between synovial membrane of RA patients and non-RA control sections by using median fluorescence intensity and the "affected area". As intensity and area are relevant parameters of in vivo imaging (e.g. PET scan) too, the presented method allows emulation of a probable outcome of in vivo imaging, i.e. the binding of the target protein and hence, the validation of the potential of the respective biomarker.

  6. Reservoir shore development in long range terrestrial laser scanning monitoring.

    NASA Astrophysics Data System (ADS)

    Kaczmarek, Halina

    2016-04-01

    Shore zones of reservoirs are in most cases very active, getting transformed as a result of coastal processes and mass movements initiated on the slopes surrounding the reservoir. From the point of view of the users of water reservoirs shore recession strongly undesirable as it causes destruction to infrastructure and buildings located in the immediate vicinity of the reservoir. For this reason, reservoir shores require continuous geodetic monitoring. Fast and accurate geodetic measurements covering shore sections several kilometers long, often in poorly accessible areas, are available using long range terrestrial laser scanning (TLS). The possibilities of using long range terrestrial laser scanning are shown on the example of the reservoir Jeziorsko on the Warta River (Central Poland). This reservoir, created in the years 1986-1992, is a typical retention reservoir, the annual fluctuations of which reach 5 m. Depending on the water level its surface area ranges from 42.3 to 19.6 km2. The width of the reservoir is 2.5 km. The total shore length of the reservoir, developed in Quaternary till and sand-till sediments, is 44.3 km, including 30.1 km of the unreinforced shore. Out of the unreinforced shore 27% is subject to coastal erosion. The cliff heights vary from a few cm to 12.5 meters, and the current rate of the cliff recession ranges from 0 to 1.12 m/y. The study used a terrestrial long range laser scanner Riegl VZ-4000 of a range of up to 4000 m. It enabled conducting the measurements of the cliff recession from the opposite shore of the reservoir, with an angular resolution of 0.002°, which gives about 50 measurement points per 1 m2. The measurements were carried out in the years 2014-2015, twice a year, in early spring before high water level, and in late autumn at a dropping water level. This allowed the separation of the impact of coastal processes and frost weathering on the cliff recession and their quantitative determination. The size and nature of

  7. Urban Road Detection in Airbone Laser Scanning Point Cloud Using Random Forest Algorithm

    NASA Astrophysics Data System (ADS)

    Kaczałek, B.; Borkowski, A.

    2016-06-01

    The objective of this research is to detect points that describe a road surface in an unclassified point cloud of the airborne laser scanning (ALS). For this purpose we use the Random Forest learning algorithm. The proposed methodology consists of two stages: preparation of features and supervised point cloud classification. In this approach we consider ALS points, representing only the last echo. For these points RGB, intensity, the normal vectors, their mean values and the standard deviations are provided. Moreover, local and global height variations are taken into account as components of a feature vector. The feature vectors are calculated on a basis of the 3D Delaunay triangulation. The proposed methodology was tested on point clouds with the average point density of 12 pts/m2 that represent large urban scene. The significance level of 15% was set up for a decision tree of the learning algorithm. As a result of the Random Forest classification we received two subsets of ALS points. One of those groups represents points belonging to the road network. After the classification evaluation we achieved from 90% of the overall classification accuracy. Finally, the ALS points representing roads were merged and simplified into road network polylines using morphological operations.

  8. Deformation Monitoring of Motorway Underpasses Using Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Puente, I.; González-Jorge, H.; Riveiro, B.; Arias, P.

    2012-07-01

    is a Optech Lynx mobile LiDAR. This laser scanner is based on time of flight technology and presents an accuracy of 6 mm in the determination of the geometrical coordinates. This accuracy can be improved to around 1 mm using fitting post-processing techniques and makes this technology very useful for studies related with deformation monitoring. The laser scanner, in comparison with other geodetic techniques as total stations, allows the control of all the structure, including unexpected deformations. Reflective targets are permanently positioned over the small walls of the structure to allow the 3D orientation of the different scans. Two main scans are made for this study, before and after the backfilling process. Backfilling takes about 10 days for the construction companies. The scans need a time of approximately 12 minutes. Construction works do not need to be interrupted during the scans. Point clouds are then post-processed using QT Modeler Software. First, the point cloud is cleaned to use only the data directly related with the structure under study. Then, using the target coordinates, both point clouds are moved to the same coordinate system. Finally, the deformation of the underpass is studied using two algorithms specifically developed using Matlab software. First algorithm fits a geometrical surface to the point cloud of the first scan and evaluates the residuals of both scans for this fitting surface. Differences in the residuals give the deformation map of the structure. Second algorithm takes a portion of the point cloud from the top of the structure, where it is located the joining point between the voussoirs. The joining between two voussoirs shows a height step that in an ideal case must tend to zero. Deformations produced by the loading of the structure are measured as a comparison between the steps before and after the backfilling process. The analysis of the results show as some deformation occurs in the structure in the joining point of the

  9. Density of point clouds in mobile laser scanning. (Polish Title: Gestosc chmury punktow pochodzacej z mobilnego skanowania laserowego)

    NASA Astrophysics Data System (ADS)

    Warchoł, A.

    2015-12-01

    The LiDAR (Light Detection And Ranging) technology is becoming a more and more popular method to collect spatial information. The acquisition of 3D data by means of one or several laser scanners mounted on a mobile platform (car) could quickly provide large volumes of dense data with centimeter-level accuracy. This is, therefore, the ideal solution to obtain information about objects with elongated shapes (corridors), and their surroundings. Point clouds used by specific applications must fulfill certain quality criteria, such as quantitative and qualitative indicators (i.e. precision, accuracy, density, completeness).Usually, the client fixes some parameter values that must be achieved. In terms of the precision, this parameter is well described, whereas in the case of density point clouds the discussion is still open. Due to the specificities of the MLS (Mobile Laser Scanning), the solution from ALS (Airborne Laser Scanning) cannot be directly applied. Hence, the density of the final point clouds, calculated as the number of points divided by "flat" surface area, is inappropriate. We present in this article three different ways of determining and interpreting point cloud density on three different test fields. The first method divides the number of points by the "flat" area, the second by the "three-dimensional" area, and the last one refers to a voxel approach. The most reliable method seems to be the voxel method, which in addition to the local density values also presents their spatial distribution.

  10. Analysis of accuracy airborne, terrestrial and mobile laser scanning data as an introduction to their integration). (Polish Title: Analiza dokładności przestrzennej danych z lotniczego, naziemnego i mobilnego skaningu laserowego jako wstęp do ich integracji)

    NASA Astrophysics Data System (ADS)

    Warchoł, A.

    2013-12-01

    The following article presents an analysis of accuracy three point clouds (airborne, terrestrial and mobile) obtained for the same area. The study was conducted separately for the coordinates (X, Y) - examining the location of buildings vertex and separately for the coordinate (Z) - comparing models built on each of the clouds. As a baseline measurement for both analyzes (X, Y and Z), the total station measurement was taken.

  11. Fluorescence liftime imaging (FLIM) using ps-pulsed diode lasers in laser scanning microscopes

    NASA Astrophysics Data System (ADS)

    Ruck, Angelika C.; Dolp, Frank; Happ, Claudia; Steiner, Rudolf; Beil, Michael

    2003-06-01

    A setup consisting on a laser scanning microscope equipped with appropriate detection units was developed for time-resolved intracellular fluorescence spectroscopy and fluorescence lifetime imaging (FLIM) for on-line detection of structural changes of various biomolecules. Short-pulsed excitation was performed with a diode laser which emits pulses at 398 nm with 70 ps duration. The laser was coupled to the laser scanning microscope. For time resolved spectroscopy a setup consisting of an Czerny Turner spectrometer and a MCP-gated and -intensified CCD camera was used. Time-gated spectra within the cells were acquired by placing the laser beam in "spot scan" mode. In addition, a time-correlated single photon counting module was used to determine the fluorescence lifetime from single spots and to record lifetime images (τ-mapping). The time-resolved fluorescence characteristics of 5-ALA (5-aminolevulinic-acid), as well as 5-ALAhe (5-aminolevulinic-acid-hexylester)- induced protoporphyrine IX (PPIX) were investigated before and during PDT with subcellular resolution. For cells which were incubated with 5-ALA, a component with a fluorescence lifetime of about 7 ns was correlated with a structured fluorescence, which probably coincides with mitochondria, whereas a shorter lifetime was found in the cytoplasm. In the case of 5-ALAhe the lifetime of PPIX was longer, which could be due to different localization. During PDT the component with the longer lifetime completely vanished, whereas the shorter liftime was retained. It seems that FLIM is a valuable method to selectively identify and localize the photodynamically active photosensitizer.

  12. Bore-Sight Calibration of Multiple Laser Range Finders for Kinematic 3D Laser Scanning Systems.

    PubMed

    Jung, Jaehoon; Kim, Jeonghyun; Yoon, Sanghyun; Kim, Sangmin; Cho, Hyoungsig; Kim, Changjae; Heo, Joon

    2015-05-04

    The Simultaneous Localization and Mapping (SLAM) technique has been used for autonomous navigation of mobile systems; now, its applications have been extended to 3D data acquisition of indoor environments. In order to reconstruct 3D scenes of indoor space, the kinematic 3D laser scanning system, developed herein, carries three laser range finders (LRFs): one is mounted horizontally for system-position correction and the other two are mounted vertically to collect 3D point-cloud data of the surrounding environment along the system's trajectory. However, the kinematic laser scanning results can be impaired by errors resulting from sensor misalignment. In the present study, the bore-sight calibration of multiple LRF sensors was performed using a specially designed double-deck calibration facility, which is composed of two half-circle-shaped aluminum frames. Moreover, in order to automatically achieve point-to-point correspondences between a scan point and the target center, a V-shaped target was designed as well. The bore-sight calibration parameters were estimated by a constrained least squares method, which iteratively minimizes the weighted sum of squares of residuals while constraining some highly-correlated parameters. The calibration performance was analyzed by means of a correlation matrix. After calibration, the visual inspection of mapped data and residual calculation confirmed the effectiveness of the proposed calibration approach.

  13. Bore-Sight Calibration of Multiple Laser Range Finders for Kinematic 3D Laser Scanning Systems

    PubMed Central

    Jung, Jaehoon; Kim, Jeonghyun; Yoon, Sanghyun; Kim, Sangmin; Cho, Hyoungsig; Kim, Changjae; Heo, Joon

    2015-01-01

    The Simultaneous Localization and Mapping (SLAM) technique has been used for autonomous navigation of mobile systems; now, its applications have been extended to 3D data acquisition of indoor environments. In order to reconstruct 3D scenes of indoor space, the kinematic 3D laser scanning system, developed herein, carries three laser range finders (LRFs): one is mounted horizontally for system-position correction and the other two are mounted vertically to collect 3D point-cloud data of the surrounding environment along the system’s trajectory. However, the kinematic laser scanning results can be impaired by errors resulting from sensor misalignment. In the present study, the bore-sight calibration of multiple LRF sensors was performed using a specially designed double-deck calibration facility, which is composed of two half-circle-shaped aluminum frames. Moreover, in order to automatically achieve point-to-point correspondences between a scan point and the target center, a V-shaped target was designed as well. The bore-sight calibration parameters were estimated by a constrained least squares method, which iteratively minimizes the weighted sum of squares of residuals while constraining some highly-correlated parameters. The calibration performance was analyzed by means of a correlation matrix. After calibration, the visual inspection of mapped data and residual calculation confirmed the effectiveness of the proposed calibration approach. PMID:25946627

  14. Utilization of scanning laser ophthalmoscopy in laser-induced bilateral human retinal nerve fiber layer damage

    NASA Astrophysics Data System (ADS)

    Zwick, Harry; Gagliano, Donald A.; Ruiz, S.; Stuck, Bruce E.

    1995-05-01

    In this paper, we describe a military laser accident case where bilateral Q-switched laser exposure resulted in bilateral macular damage with immediate visual acuity loss in one eye (OS) and delayed visual acuity loss in the other exposed eye (OD), where retinal damage appeared more parafoveal. At 6 weeks post exposure, OS had recovered to 20/17 and OD had dropped to 20/100 Snellen activity. Retinal nerve fiber damage was observed in both eyes at this time. Contrast sensitivity measurements made in OS were suppressed across all spatial frequencies, even though Snellen acuity measured in the normal range. More severe high spatial frequency loss in contrast was measured in the right eye as well as low spatial frequency loss. Both OS and OD revealed a parafoveal preferred retinal locus with scanning laser ophthalmoscopy contrast sensitivity measurements, suggesting parafoveal retinal compensatory processes.

  15. Development of an Online Archive for Terrestrial Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Crosby, Christopher; Lowry, Ben; McWhirter, Jeff; Phillips, David; Meertens, Chuck

    2013-04-01

    The UNAVCO Geodetic Imaging program provides terrestrial laser scanning (TLS) support to the Earth science research community through a TLS instrumentation pool of five scanners, field engineering, data processing, and technical training. As part of this community TLS support role, UNAVCO is responsible for generation of level one (L1) TLS data products and TLS data archive and access. A UNAVCO-organized and US National Science Foundation-funded TLS community workshop held October 2011 in Boulder, Colorado defined many of the challenges and requirements a TLS data archive and access system must address. TLS data acquisition presents unique challenges for metadata, provenance capture, and data archive. TLS datasets are often large and level zero (L0 - raw) data are stored in a variety of proprietary formats, requiring conversion and standardization for access and exchange. Due to the wide range of scientific and engineering objectives that motivate TLS data collection, field methods and collection techniques vary greatly and must be thoroughly documented in project metadata. These challenges make data and metadata capture, preservation, and provenance important objectives for an online TLS archive. To address these challenges, UNAVCO is developing a TLS archive based on the open source RAMADDA platform (http://ramadda.org). The UNAVCO TLS archive will provide online archive of L0 and L1 data products, capture field metadata and data processing workflows for provenance, and store original georeferencing information. In addition, the TLS repository provides on-demand services for simple point cloud visualization, data sub-setting and thinning, and file format (e.g., LAS, ASCII, proprietary) data conversion. The system also offers automation of RINEX processing of GPS data, OPUS and CSRS submission and solution ingestion, and generation of control point lists to streamline georeferencing of TLS point cloud data. Georeferencing metadata and GPS file provenance are

  16. Parametric modeling and optimization of laser scanning parameters during laser assisted machining of Inconel 718

    NASA Astrophysics Data System (ADS)

    Venkatesan, K.; Ramanujam, R.; Kuppan, P.

    2016-04-01

    This paper presents a parametric effect, microstructure, micro-hardness and optimization of laser scanning parameters (LSP) on heating experiments during laser assisted machining of Inconel 718 alloy. The laser source used for experiments is a continuous wave Nd:YAG laser with maximum power of 2 kW. The experimental parameters in the present study are cutting speed in the range of 50-100 m/min, feed rate of 0.05-0.1 mm/rev, laser power of 1.25-1.75 kW and approach angle of 60-90°of laser beam axis to tool. The plan of experiments are based on central composite rotatable design L31 (43) orthogonal array. The surface temperature is measured via on-line measurement using infrared pyrometer. Parametric significance on surface temperature is analysed using response surface methodology (RSM), analysis of variance (ANOVA) and 3D surface graphs. The structural change of the material surface is observed using optical microscope and quantitative measurement of heat affected depth that are analysed by Vicker's hardness test. The results indicate that the laser power and approach angle are the most significant parameters to affect the surface temperature. The optimum ranges of laser power and approach angle was identified as 1.25-1.5 kW and 60-65° using overlaid contour plot. The developed second order regression model is found to be in good agreement with experimental values with R2 values of 0.96 and 0.94 respectively for surface temperature and heat affected depth.

  17. Surveying a fossil oyster reef using terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Haring, A.; Exner, U.; Harzhauser, M.

    2009-04-01

    The Korneuburg Basin, situated north-west of Vienna, is well known to contain a rich variety of fossils from the Early Miocene (16.5 ma) and therefore has been investigated extensively by scientists in the past decades. An exceptional discovery was made in 2005: a large fossil oyster reef has been excavated and documented carefully during the last years. Aside from the giant-sized oyster (Crassostrea gryphoides), the excavation site contains numerous species of molluscs along with teeth of sharks and rays and even isolated bones of sea cows. The oysters, having lengths of up to 80 cm, are protruding from the ground surface, which is more or less a tilted plane (25˚ ) with a size of about 300 m2. The entire site is crosscut by a network of geological faults, often also offsetting individual oyster shells. Displacements along the normal faults do not exceed ~ 15 cm. The faulted fossils offer a unique opportunity to measure displacement distribution along the faults in great detail and provide insight in deformation mechanisms in porous, barely lithified sediments. In order to get a precise 3D model of the oyster reef, the terrestrial laser scanner system Leica HDS 6000 is used. It is a phase-based laser scanner, i.e. the distance measurement is performed using the phase-shift principle. Compared to the time-of-flight principle, this method is generally more appropriate to projects like this one, where the distances to be measured are relatively small (< 35 m) and where a high point density (point spacing of about 1 cm) and precision (some mm) is required for capturing the oysters adequately. However, due to fact that they occlude each other, one single scan is not sufficient to get all sides of their surface. Therefore, scans from different positions had to be acquired. These scans have to be merged, which involves the problem of sensor orientation as well as sampling of the entire 3D point cloud. Furthermore, a representation of the surface data is required that

  18. Digital Terrain Models from Mobile Laser Scanning Data in Moravian Karst

    NASA Astrophysics Data System (ADS)

    Tyagur, N.; Hollaus, M.

    2016-06-01

    During the last ten years, mobile laser scanning (MLS) systems have become a very popular and efficient technology for capturing reality in 3D. A 3D laser scanner mounted on the top of a moving vehicle (e.g. car) allows the high precision capturing of the environment in a fast way. Mostly this technology is used in cities for capturing roads and buildings facades to create 3D city models. In our work, we used an MLS system in Moravian Karst, which is a protected nature reserve in the Eastern Part of the Czech Republic, with a steep rocky terrain covered by forests. For the 3D data collection, the Riegl VMX 450, mounted on a car, was used with integrated IMU/GNSS equipment, which provides low noise, rich and very dense 3D point clouds. The aim of this work is to create a digital terrain model (DTM) from several MLS data sets acquired in the neighbourhood of a road. The total length of two covered areas is 3.9 and 6.1 km respectively, with an average width of 100 m. For the DTM generation, a fully automatic, robust, hierarchic approach was applied. The derivation of the DTM is based on combinations of hierarchical interpolation and robust filtering for different resolution levels. For the generation of the final DTMs, different interpolation algorithms are applied to the classified terrain points. The used parameters were determined by explorative analysis. All MLS data sets were processed with one parameter set. As a result, a high precise DTM was derived with high spatial resolution of 0.25 x 0.25 m. The quality of the DTMs was checked by geodetic measurements and visual comparison with raw point clouds. The high quality of the derived DTM can be used for analysing terrain changes and morphological structures. Finally, the derived DTM was compared with the DTM of the Czech Republic (DMR 4G) with a resolution of 5 x 5 m, which was created from airborne laser scanning data. The vertical accuracy of the derived DTMs is around 0.10 m.

  19. A line segment based registration method for Terrestrial Laser Scanning point cloud data

    NASA Astrophysics Data System (ADS)

    Cheng, Jun; Cheng, Ming; Lin, Yangbin; Wang, Cheng

    2016-03-01

    This paper proposed a 3d line segment based registration method for terrestrial laser scanning (TLS) data. The 3D line segment is adopted to describe the point cloud data and reduce geometric complexity. After that, we introduce a framework for registration. We demonstrate the accuracy of our method for rigid transformations in the presence of terrestrial laser scanning point cloud.

  20. Evaluation of a laser scanning sensor for variable-rate tree sprayer development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate canopy measurement capabilities are prerequisites to automate variable-rate sprayers. A 270° radial range laser scanning sensor was tested for its scanning accuracy to detect tree canopy profiles. Signals from the laser sensor and a ground speed sensor were processed with an embedded comput...

  1. The design and construction of a cost-efficient confocal laser scanning microscope

    NASA Astrophysics Data System (ADS)

    Xi, Peng; Rajwa, Bartlomiej; Jones, James T.; Robinson, J. Paul

    2007-03-01

    The optical dissection ability of confocal microscopy makes it a powerful tool for biological materials. However, the cost and complexity of confocal scanning laser microscopy hinders its wide application in education. We describe the construction of a simplified confocal scanning laser microscope and demonstrate three-dimensional projection based on cost-efficient commercial hardware, together with available open source software.

  2. Tree classification with fused mobile laser scanning and hyperspectral data.

    PubMed

    Puttonen, Eetu; Jaakkola, Anttoni; Litkey, Paula; Hyyppä, Juha

    2011-01-01

    Mobile Laser Scanning data were collected simultaneously with hyperspectral data using the Finnish Geodetic Institute Sensei system. The data were tested for tree species classification. The test area was an urban garden in the City of Espoo, Finland. Point clouds representing 168 individual tree specimens of 23 tree species were determined manually. The classification of the trees was done using first only the spatial data from point clouds, then with only the spectral data obtained with a spectrometer, and finally with the combined spatial and hyperspectral data from both sensors. Two classification tests were performed: the separation of coniferous and deciduous trees, and the identification of individual tree species. All determined tree specimens were used in distinguishing coniferous and deciduous trees. A subset of 133 trees and 10 tree species was used in the tree species classification. The best classification results for the fused data were 95.8% for the separation of the coniferous and deciduous classes. The best overall tree species classification succeeded with 83.5% accuracy for the best tested fused data feature combination. The respective results for paired structural features derived from the laser point cloud were 90.5% for the separation of the coniferous and deciduous classes and 65.4% for the species classification. Classification accuracies with paired hyperspectral reflectance value data were 90.5% for the separation of coniferous and deciduous classes and 62.4% for different species. The results are among the first of their kind and they show that mobile collected fused data outperformed single-sensor data in both classification tests and by a significant margin.

  3. Terrestrial Laser Scanning for Coastal Geomorphologic Research in Western Greece

    NASA Astrophysics Data System (ADS)

    Hoffmeister, D.; Tilly, N.; Curdt, C.; Aasen, H.; Ntageretzis, K.; Hadler, H.; Willershäuser, T.; Vött, A.; Bareth, G.

    2012-07-01

    We used terrestrial laser scanning (TLS) for (i) accurate volume estimations of dislocated boulders moved by high-energy impacts and for (ii) monitoring of annual coastal changes. In this contribution, we present three selected sites in Western Greece that were surveyed during a time span of four years (2008-2011). The Riegl LMS-Z420i laser scanner was used in combination with a precise DGPS system (Topcon HiPer Pro). Each scan position and a further target were recorded for georeferencing and merging of the point clouds. For the annual detection of changes, reference points for the base station of the DGPS system were marked. Our studies show that TLS is capable to accurately estimate volumes of boulders, which were dislocated and deposited inland from the littoral zone. The mass of each boulder was calculated from this 3D-reconstructed volume and according density data. The masses turned out to be considerably smaller than common estimated masses based on tape-measurements and according density approximations. The accurate mass data was incorporated into wave transport equations, which estimate wave velocities of high-energy impacts. As expected, these show smaller wave velocities, due to the incorporated smaller mass. Furthermore, TLS is capable to monitor annual changes on coastal areas. The changes are detected by comparing high resolution digital elevation models from every year. On a beach site, larger areas of sea-weed and sandy sediments are eroded. In contrast, bigger gravel with 30-50 cm diameter was accumulated. At the other area with bigger boulders and a different coastal configuration only slightly differences were detectable. In low-lying coastal areas and along recent beaches, post-processing of point clouds turned out to be more difficult, due to noise effects by water and shadowing effects. However, our studies show that the application of TLS in different littoral settings is an appropriate and promising tool. The combination of both instruments

  4. A laser communication experiment utilizing the ACT satellite and an airborne laser transceiver

    NASA Technical Reports Server (NTRS)

    Provencher, Charles E., Jr.; Spence, Rodney L.

    1988-01-01

    The launch of a laser communication transmitter package into geosynchronous Earth orbit onboard the Advanced Communications Technology Satellite (ACTS) will present an excellent opportunity for the experimental reception of laser communication signals transmitted from a space orbit. The ACTS laser package includes both a heterodyne transmitter (Lincoln Labs design) and a direct detection transmitter (Goddard Space Flight Center design) with both sharing some common optical components. NASA Lewis Research Center's Space Electronics Division is planning to perform a space communication experiment utilizing the GSFC direct detection laser transceiver. The laser receiver will be installed within an aircraft provided with a glass port for the reception of the signal. This paper describes the experiment and the approach to performing such an experiment. Described are the constraints placed on the NASA Lewis experiment by the performance parameters of the laser transmitter and by the ACTS spacecraft operations. The conceptual design of the receiving terminal is given; also included is the anticipated capability of the detector.

  5. Mitigation of Laser Damage Growth in Fused Silica with a Galvanometer Scanned CO2 Laser

    SciTech Connect

    Bass, I L; Guss, G M; Hackel, R P

    2005-10-28

    At the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL), mitigation of laser surface damage growth on fused silica using single and multiple CO{sub 2} laser pulses has been consistently successful for damage sites whose lateral dimensions are less than 100 {micro}m, but has not been for larger sites. Cracks would often radiate outward from the damage when a CO{sub 2} pulse was applied to the larger sites. An investigation was conducted to mitigate large surface damage sites using galvanometer scanning of a tightly focused CO{sub 2} laser spot over an area encompassing the laser damage. It was thought that by initially scanning the CO{sub 2} spot outside the damage site, radiating crack propagation would be inhibited. Scan patterns were typically inward moving spirals starting at radii somewhat larger than that of the damage site. The duration of the mitigation spiral pattern was {approx}110 ms during which a total of {approx}1.3 J of energy was delivered to the sample. The CO{sub 2} laser spot had a 1/e{sup 2}-diameter of {approx}200 {micro}m. Thus, there was general heating of a large area around the damage site while rapid evaporation occurred locally at the laser spot position in the spiral. A 30 to 40 {micro}m deep crater was typically generated by this spiral with a diameter of {approx}600 {micro}m. The spiral would be repeated until there was no evidence of the original damage in microscope images. Using this technique, damage sites as large as 300 mm in size did not display new damage after mitigation when exposed to fluences exceeding 22 J/cm{sup 2} at 355 nm, 7.5 ns. It was found necessary to use a vacuum nozzle during the mitigation process to reduce the amount of re-deposited fused silica. In addition, curing spiral patterns at lower laser powers were used to presumably ''re-melt'' any re-deposited fused silica. A compact, shearing interferometer microscope was developed to permit in situ measurement of the depth of

  6. Diffusion of photoacid generators by laser scanning confocal microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Ping L.; Webber, Stephen E.; Mendenhall, J.; Byers, Jeffrey D.; Chao, Keith K.

    1998-06-01

    Diffusion of the photogenerated acid during the period of time between exposure and development can cause contrast loss and ultimately loss of the latent image. This is especially relevant for chemically amplified photoresists that require a post-exposure baking step, which in turn facilitates acid diffusion due to the high temperature normally employed. It is thus important to develop techniques with good spatial resolution to monitor the photogeneration of acid. More precisely, we need techniques that provide two distinct types of information: spatial resolution on various length scales within the surface layer and also sufficient depth resolution so that one can observe the transition from very surface layer to bulk structure in the polymer blend coated on silicon substrate. Herein laser scanning confocal microscopy is used to evaluate the resist for the first time. We report the use of the confocal microscopy to map the pag/dye distribution in PHS matrices, with both reflectance images and fluorescence images. A laser beam is focused onto a small 3D volume element, termed a voxel. It is typically 200 nm X 200 nm laterally and 800 nm axially. The illuminated voxel is viewed such that only signals emanating from this voxel are detected, i.e., signal from outside the probed voxel is not detected. By adjusting the vertical position of the laser focal point, the voxel can be moved to the designated lateral plane to produce an image. Contrast caused by topology difference between the exposed and unexposed area can be eliminated. Bis-p-butylphenyl iodonium triflat (7% of polyhydroxystyrene) is used as photoacid generators. 5% - 18% (by weight, PHS Mn equals 13 k) resist in PGMEA solution is spin cast onto the treated quartz disk with thickness of 1.4 micrometers , 5 micrometers space/10 micrometers pitch chrome mask is used to generate the pattern with mercury DUV illumination. Fluoresceinamine, the pH-sensitive dye, is also used to enhance the contrast of

  7. Changes in pupil size following panretinal retinal photocoagulation: conventional laser vs pattern scan laser (PASCAL).

    PubMed

    Yilmaz, I; Perente, I; Saracoglu, B; Yazici, A T; Taskapili, M

    2016-10-01

    PurposeTo evaluate and compare the possible changes in pupil size subsequent to panretinal laser photocoagulation (PRP) via conventional laser and pattern scan laser (PASCAL).Patients and methodsForty eyes of 40 patients with diabetic retinopathy were included. 20 eyes had a PRP via conventional laser and formed Group 1. 20 eyes had a PRP via PASCAL laser and formed Group 2. The participants underwent standard ophthalmologic examination at baseline. Automated infrared pupillometry were performed at baseline and month 1.ResultsThe mean pupillary measurements (mm) for Group 1 (in the order photopic, mesopic, and scotopic conditions) were 2.88±0.34, 3.38±0.40, and 3.95±0.38, and changed to 3.64±0.42, 4.18±0.42, and 4.58±0.48, respectively. There was significant increase in pupil size at month 1 (P<0.001, P<0.001, and P<0.00, respectively). For Group 2, they were 2.90±0.38, 3.43±0.36, and 3.90±0.40, and changed to 3.18±0.42, 3.74±0.36, and 4.10±0.38, respectively. There was significant increase in pupil size at month 1 (P=0.018, P=0.014, and P=0.014, respectively). The pupil size increased significantly in both groups in all illumination conditions.ConclusıonWe have demonstrated via automated infrared pupillary measurements that PRP may significantly increase pupil size whether it is performed with conventional laser or PASCAL laser.

  8. Confocal laser scanning microscopy in study of bone calcification

    NASA Astrophysics Data System (ADS)

    Nishikawa, Tetsunari; Kokubu, Mayu; Kato, Hirohito; Imai, Koichi; Tanaka, Akio

    2012-12-01

    Bone regeneration in mandible and maxillae after extraction of teeth or tumor resection and the use of rough surface implants in bone induction must be investigated to elucidate the mechanism of calcification. The calcified tissues are subjected to chemical decalcification or physical grinding to observe their microscopic features with light microscopy and transmission electron microscopy where the microscopic tissue morphology is significantly altered. We investigated the usefulness of confocal laser scanning microscopy (CLSM) for this purpose. After staggering the time of administration of calcein and alizarin red to experimental rats and dogs, rat alveolar bone and dog femur grafted with coral as scaffold or dental implants were observed with CLSM. In rat alveolar bone, the calcification of newly-formed bone and net-like canaliculi was observed at the mesial bone from the roots progressed at the rate of 15 μm/day. In dog femur grafted with coral, newly-formed bones along the space of coral were observed in an orderly manner. In dog femur with dental implants, after 8 weeks, newly-formed bone proceeded along the rough surface of the implants. CLSM produced high-magnification images of newly-formed bone and thin sections were not needed.

  9. Filtering method for 3D laser scanning point cloud

    NASA Astrophysics Data System (ADS)

    Liu, Da; Wang, Li; Hao, Yuncai; Zhang, Jun

    2015-10-01

    In recent years, with the rapid development of the hardware and software of the three-dimensional model acquisition, three-dimensional laser scanning technology is utilized in various aspects, especially in space exploration. The point cloud filter is very important before using the data. In the paper, considering both the processing quality and computing speed, an improved mean-shift point cloud filter method is proposed. Firstly, by analyze the relevance of the normal vector between the upcoming processing point and the near points, the iterative neighborhood of the mean-shift is selected dynamically, then the high frequency noise is constrained. Secondly, considering the normal vector of the processing point, the normal vector is updated. Finally, updated position is calculated for each point, then each point is moved in the normal vector according to the updated position. The experimental results show that the large features are retained, at the same time, the small sharp features are also existed for different size and shape of objects, so the target feature information is protected precisely. The computational complexity of the proposed method is not high, it can bring high precision results with fast speed, so it is very suitable for space application. It can also be utilized in civil, such as large object measurement, industrial measurement, car navigation etc. In the future, filter with the help of point strength will be further exploited.

  10. Laser Scanning System for Pressure and Temperature Paints

    NASA Technical Reports Server (NTRS)

    Sullivan, John

    1997-01-01

    Acquiring pressure maps of aerodynamic surfaces is very important for improving and validating the performance of aerospace vehicles. Traditional pressure measurements are taken with pressure taps embedded in the model surface that are connected to transducers. While pressure taps allow highly accurate measurements to be acquired, they do have several drawbacks. Pressure taps do not give good spatial resolution due to the need for individual pressure tubes, compounded by limited space available inside models. Also, building a model proves very costly if taps are needed because of the large amount of labor necessary to drill, connect and test each one. The typical cost to install one tap is about $200. Recently, a new method for measuring pressure on aerodynamic surfaces has been developed utilizing a technology known as pressure sensitive paints (PSP). Using PSP, pressure distributions can be acquired optically with high spatial resolution and simple model preparation. Flow structures can be easily visualized using PSP, but are missed using low spatial resolution arrays of pressure taps. PSP even allows pressure distributions to be found on rotating machinery where previously this has been extremely difficult or even impossible. The goal of this research is to develop a laser scanning system for use with pressure sensitive paints that allows accurate pressure measurements to be obtained on various aerodynamic surfaces ranging from wind tunnel models to high speed jet engine compressor blades.

  11. Performance of a scanning laser line striper in outdoor lighting

    NASA Astrophysics Data System (ADS)

    Mertz, Christoph

    2013-05-01

    For search and rescue robots and reconnaissance robots it is important to detect objects in their vicinity. We have developed a scanning laser line striper that can produce dense 3D images using active illumination. The scanner consists of a camera and a MEMS-micro mirror based projector. It can also detect the presence of optically difficult material like glass and metal. The sensor can be used for autonomous operation or it can help a human operator to better remotely control the robot. In this paper we will evaluate the performance of the scanner under outdoor illumination, i.e. from operating in the shade to operating in full sunlight. We report the range, resolution and accuracy of the sensor and its ability to reconstruct objects like grass, wooden blocks, wires, metal objects, electronic devices like cell phones, blank RPG, and other inert explosive devices. Furthermore we evaluate its ability to detect the presence of glass and polished metal objects. Lastly we report on a user study that shows a significant improvement in a grasping task. The user is tasked with grasping a wire with the remotely controlled hand of a robot. We compare the time it takes to complete the task using the 3D scanner with using a traditional video camera.

  12. Flow cytometric and laser scanning microscopic approaches in epigenetics research.

    PubMed

    Szekvolgyi, Lorant; Imre, Laszlo; Minh, Doan Xuan Quang; Hegedus, Eva; Bacso, Zsolt; Szabo, Gabor

    2009-01-01

    Our understanding of epigenetics has been transformed in recent years by the advance of technological possibilities based primarily on a powerful tool, chromatin immunoprecipitation (ChIP). However, in many cases, the detection of epigenetic changes requires methods providing a high-throughput (HTP) platform. Cytometry has opened a novel approach for the quantitative measurement of molecules, including PCR products, anchored to appropriately addressed microbeads (Pataki et al. 2005. Cytometry 68, 45-52). Here we show selected examples for the utility of two different cytometry-based platforms of epigenetic analysis: ChIP-on-beads, a flow-cytometric test of local histone modifications (Szekvolgyi et al. 2006. Cytometry 69, 1086-1091), and the laser scanning cytometry-based measurement of global epigenetic modifications that might help predict clinical behavior in different pathological conditions. We anticipate that such alternative tools may shortly become indispensable in clinical practice, translating the systematic screening of epigenetic tags from basic research into routine diagnostics of HTP demand.

  13. Laser scanning measurements on trees for logging harvesting operations.

    PubMed

    Zheng, Yili; Liu, Jinhao; Wang, Dian; Yang, Ruixi

    2012-01-01

    Logging harvesters represent a set of high-performance modern forestry machinery, which can finish a series of continuous operations such as felling, delimbing, peeling, bucking and so forth with human intervention. It is found by experiment that during the process of the alignment of the harvesting head to capture the trunk, the operator needs a lot of observation, judgment and repeated operations, which lead to the time and fuel losses. In order to improve the operation efficiency and reduce the operating costs, the point clouds for standing trees are collected with a low-cost 2D laser scanner. A cluster extracting algorithm and filtering algorithm are used to classify each trunk from the point cloud. On the assumption that every cross section of the target trunk is approximate a standard circle and combining the information of an Attitude and Heading Reference System, the radii and center locations of the trunks in the scanning range are calculated by the Fletcher-Reeves conjugate gradient algorithm. The method is validated through experiments in an aspen forest, and the optimized calculation time consumption is compared with the previous work of other researchers. Moreover, the implementation of the calculation result for automotive capturing trunks by the harvesting head during the logging operation is discussed in particular.

  14. Semiquantitative confocal laser scanning microscopy applied to marine invertebrate ecotoxicology.

    PubMed

    Chandler, G Thomas; Volz, David C

    2004-01-01

    Confocal laser scanning microscopy (CLSM) represents a powerful, but largely unexplored ecotoxicologic tool for rapidly assessing in vivo effects of toxicants on marine invertebrate embryo quality and development. We describe here a new semiquantitative CLSM approach for assessing relative yolk quantity in marine invertebrate embryos (harpacticoid copepods) produced by parents reared from hatching to adult in the polycylic aromatic hydrocarbon chrysene. This method is based on fluorogenic labeling of embryo yolk and subsequent statistical analysis of areal pixel intensities over multiple Z-series using a general linear model (GLM)-nested analysis of variance. The fluorescent yolk-labeling method described here was able to detect statistically significant differences in yolk concentrations in marine copepod (Amphiascus tenuiremis) eggs or embryos from females exposed to ultraviolet light and chrysene-contaminated sediments. Yolk intensities in embryos from females cultured throughout their life cycles in clean sediments were statistically identical with or without UV exposure. In contrast, yolk intensities in embryos of females cultured throughout their life cycle in chrysene-contaminated sediments were significantly higher in the non-UV-exposed treatment with chrysene at 2500 ng/g sediment (65.7% higher) and the UV-exposed treatment with chrysene at 500 ng/g sediment (76.6% higher).

  15. Use of laser scanning cytometry to study tumor microenvironment.

    PubMed

    Mocellin, S; Wang, E; Panelli, M; Rossi, C R; Marincola, F M

    2003-04-01

    The study of phenomena occurring in the tumor microenvironment is a challenging task because of technical difficulties, particularly when dealing with hypocellular specimens. Laser scanning cytometry (LSC) is a new laboratory technology that has been recently introduced to overcome the limitations of other traditional technologies. By combining the properties and the advantages of flow cytometry (FC) and immunohistochemistry (IHC), LSC allows the investigator to obtain objective information on DNA content, protein expression and cellular localization is combination with morphological features. It has been already shown that LSC results are reliable compared to more traditional technologies, and its implementation in the clinical routine is under way. Its use in oncology, which is rapidly expanding, spans from apoptosis analysis to DNA content quantitation and tumor cell phenotyping. Here we describe the technology underlying this novel fluorescence-based device, review its use in oncology by dissecting the phenomena occurring in the tumor microenvironment and propose its application for the immunological follow-up of malignant lesions undergoing immunotherapeutic manipulation.

  16. Hierarchical extraction of urban objects from mobile laser scanning data

    NASA Astrophysics Data System (ADS)

    Yang, Bisheng; Dong, Zhen; Zhao, Gang; Dai, Wenxia

    2015-01-01

    Point clouds collected in urban scenes contain a huge number of points (e.g., billions), numerous objects with significant size variability, complex and incomplete structures, and variable point densities, raising great challenges for the automated extraction of urban objects in the field of photogrammetry, computer vision, and robotics. This paper addresses these challenges by proposing an automated method to extract urban objects robustly and efficiently. The proposed method generates multi-scale supervoxels from 3D point clouds using the point attributes (e.g., colors, intensities) and spatial distances between points, and then segments the supervoxels rather than individual points by combining graph based segmentation with multiple cues (e.g., principal direction, colors) of the supervoxels. The proposed method defines a set of rules for merging segments into meaningful units according to types of urban objects and forms the semantic knowledge of urban objects for the classification of objects. Finally, the proposed method extracts and classifies urban objects in a hierarchical order ranked by the saliency of the segments. Experiments show that the proposed method is efficient and robust for extracting buildings, streetlamps, trees, telegraph poles, traffic signs, cars, and enclosures from mobile laser scanning (MLS) point clouds, with an overall accuracy of 92.3%.

  17. MEMS segmented-based adaptive optics scanning laser ophthalmoscope

    PubMed Central

    Manzanera, Silvestre; Helmbrecht, Michael A.; Kempf, Carl J.; Roorda, Austin

    2011-01-01

    The performance of a MEMS (micro-electro-mechanical-system) segmented deformable mirror was evaluated in an adaptive optics (AO) scanning laser ophthalmoscope. The tested AO mirror (Iris AO, Inc, Berkeley, CA) is composed of 37 hexagonal segments that allow piston/tip/tilt motion up to 5 μm stroke and ±5 mrad angle over a 3.5 mm optical aperture. The control system that implements the closed-loop operation employs a 1:1 matched 37-lenslet Shack-Hartmann wavefront sensor whose measurements are used to apply modal corrections to the deformable mirror. After a preliminary evaluation of the AO mirror optical performance, retinal images from 4 normal subjects over a 0.9°x0.9° field size were acquired through a 6.4 mm ocular pupil, showing resolved retinal features at the cellular level. Cone photoreceptors were observed as close as 0.25 degrees from the foveal center. In general, the quality of these images is comparable to that obtained using deformable mirrors based on different technologies. PMID:21559132

  18. Laser-scan cytometry: a new tool for clinical diagnostics

    NASA Astrophysics Data System (ADS)

    Maerz, Holger K.; Baumgartner, Adolf; Hambsch, Joerg; Hennig, Bert; Nuesse, Michael; Schmid, Thomas; Schneider, Peter; Zotz, Rainer; Tarnok, Attila

    1999-04-01

    The common usage of flow cytometry (FCM) in research and clinical diagnostic is limited by the lack visualizing the fluorescence labelled cells. The Laser Scanning Cytometer (LSC) enables multicolor cytometric measurements on a slide featuring relocation of single cells for further investigation via brightfield and fluorescence microscopy. Additionally, it is possible to capture these images for documentation. In a FISH application, the LSC was successfully used for automated scoring techniqeus for evaluating the frequency of aneuploid sperm in humans and mice. In just 30 minutes, we were able to acquire more than 15,000 sperms, a task which normally takes more than a day. After relocation, genetic defects were identified and confirmed via fluorescence microscopy. In an on going study, we investigate via the LSC the remain of a new radiopaque material for high resolution echocardiography in the blood circulation. At first the result exhibited that the radiopaque material is endocysed by leukocytes just after application but is still detectable via echocardiography for up to 40 minutes. In conclusion, with the additional data acquisition by the LSC, it is possible to perform further detailed information from very small samples. Therefore, we are working up to now on developing new methods to introduce the LSC in our clinical diagnostic of neonates undergoing cardiac surgery.

  19. Multi-Pass Approach for Mobile Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Nolan, J.; Eckels, R.; Evers, M.; Singh, R.; Olsen, M. J.

    2015-08-01

    Mobile Terrestrial Laser Scanning (MTLS) has been utilised for an increasing number of corridor surveys. Current MTLS surveys require that many targets be placed along the corridor to monitor the MTLS trajectory's accuracy. These targets enable surveyors to directly evaluate the magnitude of GNSS errors at regular intervals and can also be used to adjust the trajectory to the survey control. However, this "Multi-Target" approach (MTA) is an onerous task that can significantly reduce efficiency. It also is inconvenient to the travelling public, as lanes are often blocked and traffic slowed to permit surveyors to work safely along the road corridor. This paper introduces a "Multi-Pass" approach (MPA), which minimises the number of targets required for monitoring the GNSS-controlled trajectory while still maintaining strict engineering accuracies. MPA uses the power of multiple, independent MTLS passes with different GNSS constellations to generate a "Control Polyline" from the point cloud for the corridor. The Control Polyline can be considered as a statistically valid survey measurement and be incorporated in a network adjustment to strengthen a control network by identifying outliers. Results from a test survey at the MTLS course maintained by the Oregon Department of Transportation illustrate the effectiveness of this approach.

  20. Multispectral Analysis of Indigenous Rock Art Using Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Skoog, B.; Helmholz, P.; Belton, D.

    2016-06-01

    Multispectral analysis is a widely used technique in the photogrammetric and remote sensing industry. The use of Terrestrial Laser Scanning (TLS) in combination with imagery is becoming increasingly common, with its applications spreading to a wider range of fields. Both systems benefit from being a non-contact technique that can be used to accurately capture data regarding the target surface. Although multispectral analysis is actively performed within the spatial sciences field, its extent of application within an archaeological context has been limited. This study effectively aims to apply the multispectral techniques commonly used, to a remote Indigenous site that contains an extensive gallery of aging rock art. The ultimate goal for this research is the development of a systematic procedure that could be applied to numerous similar sites for the purpose of heritage preservation and research. The study consisted of extensive data capture of the rock art gallery using two different TLS systems and a digital SLR camera. The data was combined into a common 2D reference frame that allowed for standard image processing to be applied. An unsupervised k-means classifier was applied to the multiband images to detect the different types of rock art present. The result was unsatisfactory as the subsequent classification accuracy was relatively low. The procedure and technique does however show potential and further testing with different classification algorithms could possibly improve the result significantly.

  1. Structural damage detection and estimation using a scanning laser vibrometer

    NASA Astrophysics Data System (ADS)

    Pai, Perngjin F.; Lee, Seung-Yoon; Schulz, Mark J.

    2001-07-01

    This paper presents a model-independent boundary effect evaluation (BEE) method for pinpointing crack locations and estimating crack sizes using only operational deflection shapes (ODSs) measured by a scanning laser vibrometer. An ODS consists of central and boundary solutions. Central solutions are periodic functions, and boundary solutions are exponentially decaying functions due to boundary constraints. The BEE method uses a sliding-window curve-fitting technique to extract boundary solutions from an experimental ODS. Because cracks introduce localized small boundaries to a structure, boundary solutions exist around cracks as well as structural boundaries. Since crack-induced boundary solutions show characteristics different from those of actual boundaries, cracks can be easily located. A local strain energy method is derived for estimating crack sizes. In the method, the crack-induced strain energy extracted from an ODS is compared with the one calculated using fracture mechanics to estimate the crack size. To verify the capability and accuracy of this BEE method, experiments are performed on six 22' X 1' X 0.25' 2024-T4 aluminum beams each having a through-the-width Mode I crack at its midpoint. These cracks are slots having a width of 0.039' and depths of 0.0625' (25% of the beam thickness), 0.05' (20%), 0.0375' (15%), 0.025' (10%), 0.0125' (5%), and 0.005' (2%), respectively. Results show that this BEE method is capable of locating and estimating small cracks.

  2. Managing multiple image stacks from confocal laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Zerbe, Joerg; Goetze, Christian H.; Zuschratter, Werner

    1999-05-01

    A major goal in neuroanatomy is to obtain precise information about the functional organization of neuronal assemblies and their interconnections. Therefore, the analysis of histological sections frequently requires high resolution images in combination with an overview about the structure. To overcome this conflict we have previously introduced a software for the automatic acquisition of multiple image stacks (3D-MISA) in confocal laser scanning microscopy. Here, we describe a Windows NT based software for fast and easy navigation through the multiple images stacks (MIS-browser), the visualization of individual channels and layers and the selection of user defined subregions. In addition, the MIS browser provides useful tools for the visualization and evaluation of the datavolume, as for instance brightness and contrast corrections of individual layers and channels. Moreover, it includes a maximum intensity projection, panning and zoom in/out functions within selected channels or focal planes (x/y) and tracking along the z-axis. The import module accepts any tiff-format and reconstructs the original image arrangement after the user has defined the sequence of images in x/y and z and the number of channels. The implemented export module allows storage of user defined subregions (new single image stacks) for further 3D-reconstruction and evaluation.

  3. Automatic analysis for neuron by confocal laser scanning microscope

    NASA Astrophysics Data System (ADS)

    Satou, Kouhei; Aoki, Yoshimitsu; Mataga, Nobuko; Hensh, Takao K.; Taki, Katuhiko

    2005-12-01

    The aim of this study is to develop a system that recognizes both the macro- and microscopic configurations of nerve cells and automatically performs the necessary 3-D measurements and functional classification of spines. The acquisition of 3-D images of cranial nerves has been enabled by the use of a confocal laser scanning microscope, although the highly accurate 3-D measurements of the microscopic structures of cranial nerves and their classification based on their configurations have not yet been accomplished. In this study, in order to obtain highly accurate measurements of the microscopic structures of cranial nerves, existing positions of spines were predicted by the 2-D image processing of tomographic images. Next, based on the positions that were predicted on the 2-D images, the positions and configurations of the spines were determined more accurately by 3-D image processing of the volume data. We report the successful construction of an automatic analysis system that uses a coarse-to-fine technique to analyze the microscopic structures of cranial nerves with high speed and accuracy by combining 2-D and 3-D image analyses.

  4. Intracellular phthalocyanine localization: confocal laser scanning microscopy studies

    NASA Astrophysics Data System (ADS)

    Chernyaeva, Elena B.; Greve, Jan; de Grooth, Bart G.; Van Leeuwen, A. G.

    1994-02-01

    Phthalocyanines (Pc) are promising second-generation photosensitizers for the photodynamic therapy (PDT) of cancer. We report on the tetrasulfonated aluminum phthalocyanine (AlPcS4) localization in cultured Chinese hamster lung cells studied by means of confocal laser scanning microscopy (CLSM). In these cells AlPcS4 was found in granules surrounding Golgi apparatus and in the peripheral cytoplasmic region. Peripheral Pc-containing granules partially coincided with the acidic cellular compartments. The effect of irradiation with light on Pc intracellular distribution was also studied. In the Pc-free medium disruption of some Pc- containing granules was observed followed by appearance of Pc fluorescence in the cell plasma membrane, the nuclear envelope, and the near-nuclear region. When cells were irradiated in the presence of Pc in external medium a drastic increase of membrane permeability to Pc was observed, followed by Pc binding the cell plasma membrane, nuclear envelope, and some structures in the cytoplasm. Diffusive Pc fluorescence in the nucleus was also observed. The implication of observed Pc redistribution caused by irradiation with light for the PDT protocol is discussed.

  5. Laser scanning dental probe for endodontic root canal treatment

    NASA Astrophysics Data System (ADS)

    Blank, Molly A. B.; Friedrich, Michal; Hamilton, Jeffrey D.; Lee, Peggy; Berg, Joel; Seibel, Eric J.

    2011-03-01

    Complications that arise during endodontic procedures pose serious threats to the long-term integrity and health of the tooth. Potential complexities of root canals include residual pulpal tissue, cracks, mesial-buccal 2 and accessory canals. In the case of a failed root canal, a successful apicoectomy can be jeopardized by isthmuses, accessory canals, and root microfracture. Confirming diagnosis using a small imaging probe would allow proper treatment and prevent retreatment of endodontic procedures. An ultrathin and flexible laser scanning endoscope of 1.2 to 1.6mm outer diameter was used in vitro to image extracted teeth with varied root configurations. Teeth were opened using a conventional bur and high speed drill. Imaging within the opened access cavity clarified the location of the roots where canal filing would initiate. Although radiographs are commonly used to determine the root canal size, position, and shape, the limited 2D image perspective leaves ambiguity that could be clarified if used in conjunction with a direct visual imaging tool. Direct visualization may avoid difficulties in locating the root canal and reduce the number of radiographs needed. A transillumination imaging device with the separated illumination and light collection functions rendered cracks visible in the prepared teeth that were otherwise indiscernible using reflected visible light. Our work demonstrates that a small diameter endoscope with high spatial resolution may significantly increase the efficiency and success of endodontic procedures.

  6. Algorithm for registration of full Scanning Laser Ophthalmoscope video sequences.

    PubMed

    Mariño, C; Ortega, M; Barreira, N; Penedo, M G; Carreira, M J; González, F

    2011-04-01

    Fluorescein angiography is an established technique for examining the functional integrity of the retinal microcirculation for early detection of changes due to retinopathy. This paper describes a new method for the registration of large Scanning Laser Ophthalmoscope sequences (SLO), where the patient has been injected with a fluorescent dye. This allows the measurement of parameters such as the arteriovenous passage time. Due to the long time needed to acquire these sequences, there will inevitably be eye movement, which must be corrected prior to the application of quantitative analysis. The algorithm described here combines mutual information-based registration and landmark-based registration. The former will allow the alignment of the darkest frames of the sequence, where the dye has not still arrived to the retina, because of its ability to work with images without a preprocessing or segmentation, while the latter uses relevant features (the vessels) extracted by means of a robust creaseness operator, to get a very fast and accurate registration. The algorithm only detects rigid transformations but proves to be robust against the slight alterations derived from the eye location perspective during acquisition. Results were validated by expert clinicians.

  7. Laser Scanning Measurements on Trees for Logging Harvesting Operations

    PubMed Central

    Zheng, Yili; Liu, Jinhao; Wang, Dian; Yang, Ruixi

    2012-01-01

    Logging harvesters represent a set of high-performance modern forestry machinery, which can finish a series of continuous operations such as felling, delimbing, peeling, bucking and so forth with human intervention. It is found by experiment that during the process of the alignment of the harvesting head to capture the trunk, the operator needs a lot of observation, judgment and repeated operations, which lead to the time and fuel losses. In order to improve the operation efficiency and reduce the operating costs, the point clouds for standing trees are collected with a low-cost 2D laser scanner. A cluster extracting algorithm and filtering algorithm are used to classify each trunk from the point cloud. On the assumption that every cross section of the target trunk is approximate a standard circle and combining the information of an Attitude and Heading Reference System, the radii and center locations of the trunks in the scanning range are calculated by the Fletcher-Reeves conjugate gradient algorithm. The method is validated through experiments in an aspen forest, and the optimized calculation time consumption is compared with the previous work of other researchers. Moreover, the implementation of the calculation result for automotive capturing trunks by the harvesting head during the logging operation is discussed in particular. PMID:23012543

  8. Terrestrial Laser Scanning of Peatland Surface Morphology for Eco-Hydrological Applications

    NASA Astrophysics Data System (ADS)

    Anderson, Karen; Bennie, Jonathan; Wetherelt, Andrew

    2010-05-01

    point clouds permitted measurement of the typical grain sizes of peatland structures, and allowed us to capture the texture and length-scale of hummock-hollow topography, shrub canopy and peatland morphological features. Results demonstrate, for the first time, the advantages of laser scanning methodologies for rapid measurement of 3-dimensional vegetation canopy structure and surface microtopography, at fine spatial scales, in short vegetation. We demonstrate how adoption of such approaches can provide quantitative, spatial data for description of peatland structure, which is inherently linked to eco-hydrological function. SUMMARY OF KEY FINDINGS: Specifically, our results show: (a) The spatial scale (grain size) of vegetation patterning and microtopography in peatland systems. We demonstrate that intact plots on the peat dome with hummock-hollow topography have a distinctive fine-scale isotropic pattern with a range of <1 m. drained plots, where hummock-hollow microtopes are reduced show lower semivariance at this lag. (b) The optimal spatial resolution for surveying changes in vegetation pattern and structure on peatlands. The study suggests that scaling up the method proposed here to airborne LiDAR is plausible. Other work following this project has already investigated this potential and brief results will be shown.

  9. Wind Tunnel Testing of a One-Dimensional Laser Beam Scanning and Laser Sheet Approach to Shock Sensing

    NASA Technical Reports Server (NTRS)

    Tokars, Roger; Adamovsky, Grigory; Anderson, Robert; Hirt, Stefanie; Huang, John; Floyd, Bertram

    2012-01-01

    A 15- by 15-cm supersonic wind tunnel application of a one-dimensional laser beam scanning approach to shock sensing is presented. The measurement system design allowed easy switching between a focused beam and a laser sheet mode for comparison purposes. The scanning results were compared to images from the tunnel Schlieren imaging system. The tests revealed detectable changes in the laser beam in the presence of shocks. The results lend support to the use of the one-dimensional scanning beam approach for detecting and locating shocks in a flow, but some issues must be addressed in regards to noise and other limitations of the system.

  10. Case studies of optical ringing for airborne lasers seeing into sea water

    NASA Astrophysics Data System (ADS)

    Gilbert, Gary D.; North, Mark H.

    1996-11-01

    Airborne lidars systems have progressed to the point where they are increasingly being used in surveys and bathymetric studies of coastal and littoral zones. Scattered laser pulse light in these turbid regions hurt the performance of lidar system s as photons delayed by multiple scattering simultaneously return with the signal from a distant target. This phenomenon is called 'optical ringing' and is analogous to reverberation in acoustics. A Monte Carlo model was used to examine the effect of water turbidity on the temporal storage of photons in increasing scattering orders for an airborne lidar. The lidars modeled had combinations of both wide and narrow source and receiver fields. The lidar looked at nadir into a flat clam sea with optical properties ranging from clear to turbid water. The amount of optical ringing present in a return was proportional to the size of the pulse-illuminated in water volume. The results showed multiple scattered light surpassing single scattered light returns for all cases of source-receiver field combinations for even the clearest water studied.

  11. Inviscid Flow Field Effects: Experimental results. [optical distortions over airborne laser turrets

    NASA Technical Reports Server (NTRS)

    Otten, L. J., III; Gilbert, K. G.

    1980-01-01

    The aero-optical distortions due to invisid flow effects over airborne laser turrets is investigated. Optical path differences across laser turret apertures are estimated from two data sources. The first is a theoretical study of main flow effects for a spherical turret assembly for a Mach number (M) of 0.6. The second source is an actual wind tunnel density field measurement on a 0.3 scale laser turret/fairing assembly, with M = 0.75. A range of azimuthal angles from 0 to 90 deg was considered, while the elevation angle was always 0 deg (i.e., in the plane of the flow). The calculated optical path differences for these two markedly different geometries are of the same order. Scaling of results to sea level conditions and an aperture diameter of 50 cm indicated up to 0.0007 cm of phase variation across the aperture for certain forward look angles and a focal length of F = -11.1 km. These values are second order for a 10.6 micron system.

  12. Multi-Target Detection from Full-Waveform Airborne Laser Scanner Using Phd Filter

    NASA Astrophysics Data System (ADS)

    Fuse, T.; Hiramatsu, D.; Nakanishi, W.

    2016-06-01

    We propose a new technique to detect multiple targets from full-waveform airborne laser scanner. We introduce probability hypothesis density (PHD) filter, a type of Bayesian filtering, by which we can estimate the number of targets and their positions simultaneously. PHD filter overcomes some limitations of conventional Gaussian decomposition method; PHD filter doesn't require a priori knowledge on the number of targets, assumption of parametric form of the intensity distribution. In addition, it can take a similarity between successive irradiations into account by modelling relative positions of the same targets spatially. Firstly we explain PHD filter and particle filter implementation to it. Secondly we formulate the multi-target detection problem on PHD filter by modelling components and parameters within it. At last we conducted the experiment on real data of forest and vegetation, and confirmed its ability and accuracy.

  13. Airborne laser-guided imaging spectroscopy to map forest trait diversity and guide conservation.

    PubMed

    Asner, G P; Martin, R E; Knapp, D E; Tupayachi, R; Anderson, C B; Sinca, F; Vaughn, N R; Llactayo, W

    2017-01-27

    Functional biogeography may bridge a gap between field-based biodiversity information and satellite-based Earth system studies, thereby supporting conservation plans to protect more species and their contributions to ecosystem functioning. We used airborne laser-guided imaging spectroscopy with environmental modeling to derive large-scale, multivariate forest canopy functional trait maps of the Peruvian Andes-to-Amazon biodiversity hotspot. Seven mapped canopy traits revealed functional variation in a geospatial pattern explained by geology, topography, hydrology, and climate. Clustering of canopy traits yielded a map of forest beta functional diversity for land-use analysis. Up to 53% of each mapped, functionally distinct forest presents an opportunity for new conservation action. Mapping functional diversity advances our understanding of the biosphere to conserve more biodiversity in the face of land use and climate change.

  14. Airborne Measurements of Formaldehyde Employing a Tunable Diode Laser Absorption Spectrometer During TRACE-P

    NASA Technical Reports Server (NTRS)

    Fried, Alan; Drummond, James

    2003-01-01

    This final report summarizes the progress achieved over the entire 3-year proposal period including two extensions spanning 1 year. These activities include: 1) Preparation for and participation in the NASA 2001 TRACE-P campaign using our airborne tunable diode laser system to acquire measurements of formaldehyde (CH2O); 2) Comprehensive data analysis and data submittal to the NASA archive; 3) Follow up data interpretation working with NASA modelers to place our ambient CH2O measurements into a broader photochemical context; 4) Publication of numerous JGR papers using this data; 5) Extensive follow up laboratory tests on the selectivity and efficiency of our CH20 scrubbing system; and 6) An extensive follow up effort to assess and study the mechanical stability of our entire optical system, particularly the multipass absorption cell, with aircraft changes in cabin pressure.

  15. A digital elevation model of the Greenland ice sheet and validation with airborne laser altimeter data

    NASA Technical Reports Server (NTRS)

    Bamber, Jonathan L.; Ekholm, Simon; Krabill, William B.

    1997-01-01

    A 2.5 km resolution digital elevation model (DEM) of the Greenland ice sheet was produced from the 336 days of the geodetic phase of ERS-1. During this period the altimeter was operating in ice-mode over land surfaces providing improved tracking around the margins of the ice sheet. Combined with the high density of tracks during the geodetic phase, a unique data set was available for deriving a DEM of the whole ice sheet. The errors present in the altimeter data were investigated via a comparison with airborne laser altimeter data obtained for the southern half of Greenland. Comparison with coincident satellite data showed a correlation with surface slope. An explanation for the behavior of the bias as a function of surface slope is given in terms of the pattern of surface roughness on the ice sheet.

  16. Revision and update of the EGIB land-use database using the airborne laser scanning point cloud - the case study of Tuklecz village in 'wietokrzyskie voivodeship. (Polish Title: Weryfikacja i aktualizacja bazy klaso-użytków EGIB w oparciu o analizy chmury punktów z lotniczego skanowania laserowego na przykładzie wsi Tuklęcz w województwie świętokrzyskim)

    NASA Astrophysics Data System (ADS)

    Wężyk, P.; Gęca, T.

    2013-12-01

    Dynamic economic and social changes taking place for the past 20 years in Poland, effects often of such loss of extensive agriculture and abandonment of agricultural activities particularly on small and narrow plots , usually on the soils of poor grading. Even before the Polish accession to the EU, set - aside and fallow areas cover approx. 2.3 million ha (in 2002), but in subsequent years the area drastically decreased from 1.3 million ha (in 2004) , by 1.0 million ha ( 2 005 ) to 0.4 million hectares (2011). As a result of cessation of mowing meadows, grazing pastures and agricultural measures , we can observed the phenomenon of secondary forest succession ( plant communities of a forest properties ) leading to changes in land use and land cover classes structure . Recording changes in the agro - forestry space, update reference registers of the land and building (EGiB) and control granted to farmers subsidies ( direct EU payments) requires an efficient and automated technology acquisition, processing and analysis of spatial data. In addition to the used by ARiMR (in the LPIS system) vector data and aerial orthophotomaps , there is still a need to strengthen the decision - making process such as update of current ranges of land - use cla sses. One of the GI technologies that could be a real breakthrough is the Airborne Laser Scanning (ALS) . The study area cover 137.17 ha in the village Tuklęcz (commune Rytwiany, Staszów County , ?więtokrzyskie Voivodeship ). The EGiB geo data came from PODGiK in Staszów. They were two ALS point cloud data sets: one provided by the RZGW in Krakow (from airborne campaign Nov. 2009; density ~ 2 pts / m2) and the second from ISOK project (Nov. 2012; density ~ 4 pts / m2 ). The Terrasolid and FUSION (USDA Forest Service) and ArcGIS Esri software were used in the study . Detection of vegetation was carried out in 4 variants differ in the "height above ground" of the class "succession" (thresholds: from 0.4m , 1m, 2m and 3m ). The

  17. Airborne laser scanner aided inertial for terrain referenced navigation in unknown environments

    NASA Astrophysics Data System (ADS)

    Vadlamani, Ananth Kalyan

    A dead-reckoning terrain referenced navigation (TRN) system that uses airborne laser ranging sensors to aid an aircraft inertial navigation system (INS) is presented. Improved navigation performance is achieved through estimation of vehicle velocity and position using terrain measurements. The system only uses aircraft sensors and simultaneously performs the dual functions of mapping and navigation in unknown environments. The theory, algorithms and results of the system performance are presented using simulations and flight test data. This dissertation focuses primarily on the use of dual airborne laser scanners (ALS) for aiding an INS. Dual ALS measurements are used to generate overlapping terrain models, which are then used to estimate the INS velocity and position errors and constrain its drift. By keeping track of its errors, a navigation-grade INS is aided in a feed-forward manner. This dead-reckoning navigation algorithm is generic enough to be easily extendable to use other optical sensors. Data integrity, sensor alignment and the effects of vegetation noise, attitude and heading accuracy are analyzed. Furthermore, a feedback coupled aiding scheme is presented in which a tactical-grade inertial measurement unit (IMU) is aided with dual ALS measurements by feeding the estimated velocity back into the IMU computations. The proposed system can potentially serve as a backup during temporary Global Positioning System (GPS) signal outages, or it can be used to coast for extended periods of time. Although it has elements of conventional TRN, this system does not require a terrain database since its in-flight mapping capability generates the terrain data for navigation. Hence, the system can be used in both non-GPS as well as unknown terrain environments. The navigation system is dead-reckoning in nature and errors accumulate over time, unless the system can be reset periodically by geo-referenced terrain data or a position estimate from another navigation aid.

  18. Design and development of multi functional confocal laser scanning microscope with UV / VIS laser source

    NASA Astrophysics Data System (ADS)

    Kanai, Yoshikazu; Kanzaki, Yousuke; Wakaki, Moriaki; Takeyama, Norihide

    2005-08-01

    A high resolution Confocal Laser Scanning Microscope (CLSM) with UV / VIS light sources was developed as the first step of multi-functional microscope. The optical system is designed to optimize for both UV and VIS wavelengths. An UV laser is used to achieve higher resolution, and a VIS is for multi functions. A new objective lens specialized for this application was designed and fabricated. Specification of the lens and the optical system is NA:0.95, EFL:2.5mm, WD:1.5mm, Resolution:160nm and achromatic for two wavelengths of UV 325.0nm / VIS 632.8nm. Several specimens were characterized to check the performance of the system. Some optical materials under study were measured for evaluation, and interesting results could be obtained. Multi-functional measurements are being planed as a next step. This system will help the research of nano-structures, photonic-crystals and biology.

  19. Modelling Braided River Morphodynamics With Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Brasington, J.; Wheaton, J. M.; Vericat, D.; Hodge, R.

    2007-12-01

    Advances in topographic survey and terrain modelling have enabled a revolution in the study in the fluvial morphodynamics in the last decade. Prior to the advent of electronic tacheometry in the 1990s, the analysis of channel dynamics was typically inferred from a combination of cross-section surveys and planform mapping. Distributed surveys acquired with GPS or EDMs enabled this analysis to be dimensionally extended and the pattern and magnitude morphodynamics elucidated in 3D; in particular through DTM differencing. Continuing developments in survey technology are now posed to reset this field once again. Now no longer confined to the laboratory, ruggedized laser scanners are capable of acquiring between 4-50,000 observations per second, at ranges exceeding 100 m. This latest development creates the potential for typical reach-scale (1-10 km) topographic datasets to rise in size by 7 orders of magnitude (hundreds to billions of points) in the coming years. Terrestrial Laser Scanning (TLS) offers a wealth of opportunities to better monitor fluvial systems; improving models of cut-and-fill, roughness and enhancing the prospect for ever more detailed parameterizations for fluid models. While this technology enables the creation of 'virtual facsimiles' of landscapes, the demands of storing, processing and modelling geomorphological products from such data requires a wholesale reappraisal of our data management and modelling methods. Here we outline a field-to-product methodology for TLS of fluvial systems using data from two annual surveys of a 1 km reach of the River Feshie, Scotland. These surveys delivered 3D point cloud datasets, incorporating over 200 million xyz observations, with median spatial densities of over 1000 pts/m2. The surveys were fixed to a GPS-based control network, including over 200 coincident tie- points to register multiple setups to a global coordinate system (RMS errors 0.002-0.011 m). Modelling reach-scale geometries from such dense point

  20. Remote z-scanning with a macroscopic voice coil motor for fast 3D multiphoton laser scanning microscopy

    PubMed Central

    Rupprecht, Peter; Prendergast, Andrew; Wyart, Claire; Friedrich, Rainer W

    2016-01-01

    There is a high demand for 3D multiphoton imaging in neuroscience and other fields but scanning in axial direction presents technical challenges. We developed a focusing technique based on a remote movable mirror that is conjugate to the specimen plane and translated by a voice coil motor. We constructed cost-effective z-scanning modules from off-the-shelf components that can be mounted onto standard multiphoton laser scanning microscopes to extend scan patterns from 2D to 3D. Systems were designed for large objectives and provide high resolution, high speed and a large z-scan range (>300 μm). We used these systems for 3D multiphoton calcium imaging in the adult zebrafish brain and measured odor-evoked activity patterns across >1500 neurons with single-neuron resolution and high signal-to-noise ratio. PMID:27231612

  1. Advances and perspectives in bathymetry by airborne lidar

    NASA Astrophysics Data System (ADS)

    Zhou, Guoqing; Wang, Chenxi; Li, Mingyan; Wang, Yuefeng; Ye, Siqi; Han, Caiyun

    2015-12-01

    In this paper, the history of the airborne lidar and the development stages of the technology are reviewed. The basic principle of airborne lidar and the method of processing point-cloud data were discussed. At present, single point laser scanning method is widely used in bathymetric survey. Although the method has high ranging accuracy, the data processing and hardware system is too much complicated and expensive. For this reason, this paper present a kind of improved dual-frequency method for bathymetric and sea surface survey, in this method 176 units of 1064nm wavelength laser has been used by push-broom scanning and due to the airborne power limits still use 532nm wavelength single point for bathymetric survey by zigzag scanning. We establish a spatial coordinates for obtaining the WGS-84 of point cloud by using airborne POS system.

  2. Airborne Polarimetric, Two-Color Laser Altimeter Measurements of Lake Ice Cover: A Pathfinder for NASA's ICESat-2 Spaceflight Mission

    NASA Technical Reports Server (NTRS)

    Harding, David; Dabney, Philip; Valett, Susan; Yu, Anthony; Vasilyev, Aleksey; Kelly, April

    2011-01-01

    The ICESat-2 mission will continue NASA's spaceflight laser altimeter measurements of ice sheets, sea ice and vegetation using a new measurement approach: micropulse, single photon ranging at 532 nm. Differential penetration of green laser energy into snow, ice and water could introduce errors in sea ice freeboard determination used for estimation of ice thickness. Laser pulse scattering from these surface types, and resulting range biasing due to pulse broadening, is assessed using SIMPL airborne data acquired over icecovered Lake Erie. SIMPL acquires polarimetric lidar measurements at 1064 and 532 nm using the micropulse, single photon ranging measurement approach.

  3. Cosmetic and aesthetic skin photosurgery using a computer-assisted CO2 laser-scanning system

    NASA Astrophysics Data System (ADS)

    Dutu, Doru C. A.; Dumitras, Dan C.; Nedelcu, Ioan; Ghetie, Sergiu D.

    1997-12-01

    Since the first application of CO2 laser in skin photosurgery, various techniques such as laser pulsing, beam scanning and computer-assisted laser pulse generator have been introduced for the purpose of reducing tissue carbonization and thermal necrosis. Using a quite simple XY optical scanner equipped with two galvanometric driven mirrors and an appropriate software to process the scanning data and control the interaction time and energy density in the scanned area, we have obtained a device which can improve CO2 laser application in cosmetic and aesthetic surgery. The opto-mechanical CO2 laser scanner based on two total reflecting flat mirrors placed at 90 degree(s) in respect to the XY scanning directions and independently driven through a magnetic field provides a linear movement of the incident laser beam in the operating field. A DA converter supplied with scanning data by the software enables a scanning with linearity better than 1% for a maximum angular deviation of 20 degree(s). Because the scanning quality of the laser beam in the operating field is given not only by the displacement function of the two mirrors, but also by the beam characteristics in the focal plane and the cross distribution in the laser beam, the surgeon can control through software either the scanning field dimensions or the distance between two consecutive points of the vertically and/or horizontally sweep line. The development of computer-assisted surgical scanning techniques will help control the surgical laser, to create either a reproducible incision with a controlled depth or a controlled incision pattern with minimal incision width, a long desired facility for plastic surgery, neurosurgery, ENT and dentistry.

  4. An Overview of Raster Scanning for ICF-Class Laser Optics

    SciTech Connect

    Runkel, M J; Nostrand, M

    2002-10-30

    Recent work has shown that the damage resistance of both ICF-class (1600 cm') DKDP tripler crystals and SiO{sub 2} components (lenses, gratings and debris shields) benefits from laser raster scanning using pulsed lasers in the 350 nm range. For laser raster scanning to be a viable optical improvement tool for these large optics, damage improvement must be optimized while maintaining scan times of less than 8 hours/optic. In this paper we examine raster scanning with small beams from tabletop laser systems. We show that 120 Watts of average power is required for a tabletop scanning system at one optic/day. Next, we develop equations for total scan time for square and round top hat beams and round and rectangular Gaussian beams. We also consider the effect of packing geometry (square vs. hexagonal), examine the deviations from uniform coverage with each scan geometry and show that hexagonal packing yields lower scan times but is less efficient in coverage than square geometry. We also show that multiple passes at low packing densities are temporally equivalent to a single pass with higher packing density, and discuss the advantages of each method. In addition, we show that the differences between hexagonal and square scan geometries are negated when pointing errors and fluence fluctuations from the laser are considered.

  5. Phase Sequence Estimation for Laser Line-Scan Imagery in the Presence of Rayleigh Fading.

    DTIC Science & Technology

    1979-12-01

    Warning Radar for Det 4, 14 Missle Warning Squadron, Mt. Laguna AFS, California. In May 1975, he was assigned to the 1961st Communications Group, Clark Air...unlimited Preface This study was prompted by a phase estimation problem of a fading signal in a laser line-scan imagery system . The sys- tem is sponsored by...114 ii I List of Figures Figure 1 Geometry of the Laser Line-scan System . . . . .. 3 2. Block Diagram of Laser Line-scan Imagery System . 4 3

  6. Understanding the structure of Exmoor's peatland ecosystems using laser-scanning technologies

    NASA Astrophysics Data System (ADS)

    Luscombe, D. J.; Anderson, K.; Wetherelt, A.; Grand-Clement, E.; Le-Feuvre, N.; Smith, D.; Brazier, R. E.

    2012-04-01

    Upland blanket peatlands in the UK are of high conservation value and in an intact state, provide important landscape services, such as carbon sequestration and flood attenuation. The drainage of many such wetlands for agricultural reclamation has resulted in changes to upland blanket mire topography, ecology, hydrological processes and carbon fluxes. There is a need for spatially explicit monitoring approaches at peatland sites in the UK as although there has been a national effort to restore drained peat uplands, baseline and post restoration monitoring of changes to ecosystem structure and function is largely absent. Climate change policy and the emerging carbon markets also necessitate the need for enhanced system understanding to inform carbon targets and understand the impacts of restoration. Exmoor is the focus of this research because many areas of upland peat have, in the past, been extensively drained through government "moorland reclamation" programs. A large restoration project funded by South West Water is currently underway in association with Exmoor National Park, The Environment Agency and Natural England. Exmoor also provides an analogue for other westerly peatlands in the British Isles in terms of its climate, ecology and drainage characteristics. Our approach employed airborne LiDAR data gathered by the Environment Agency Geomatics Group coupled with Terrestrial Laser Scanning (TLS) surveys. LiDAR data were processed to produce digital surface models (DSM) of the peatland surface at a 0.5m resolution. These data were further interrogated to separate vegetation structures and geomorphic features such as man-made drainage channels which have damaged the peatland. Over small extents the LiDAR derived DSM surface was then compared to a TLS derived DSM to examine the ability of these models to describe fine scale vegetation and geomorphic structure, which could then be extrapolated to larger spatial extents. Exploration of the data has shown that

  7. Characterization of an Airborne Laser-Spark Ion Source for Ambient Mass Spectrometry.

    PubMed

    Bierstedt, Andreas; Kersten, Hendrik; Glaus, Reto; Gornushkin, Igor; Panne, Ulrich; Riedel, Jens

    2017-03-07

    An airborne laser plasma is suggested as an ambient ion source for mass spectrometry. Its fundamental physical properties, such as an excellent spatial and temporal definition, high electron and ion densities and a high effective cross section in maintaining the plasma, make it a promising candidate for future applications. For deeper insights into the plasma properties, the optical plasma emission is examined and compared to mass spectra. The results show a seemingly contradictory behavior, since the emitted light reports the plasma to almost entirely consist of hot elemental ions, while the corresponding mass spectra exhibit the formation of intact molecular species. Further experiments, including time-resolved shadowgraphy, spatially resolved mass spectrometry, as well as flow-dependent emission spectroscopy and mass spectrometry, suggest the analyte molecules to be formed in the cold plasma vicinity upon interaction with reactive species formed inside the hot plasma center. Spatial separation is maintained by concentrically expanding pressure waves, inducing a strong unidirectional diffusion. The accompanying rarefaction inside the plasma center can be compensated by a gas stream application. This replenishing results in a strong increase in emission brightness, in local reactive species concentration, and eventually in direct mass spectrometric sensitivity. To determine the analytical performance of the new technique, a comparison with an atmospheric pressure chemical ionization (APCI) source was conducted. Two kitchen herbs, namely, spearmint and basil, were analyzed without any sample pretreatment. The presented results demonstrate a considerably higher sensitivity of the presented laser-spark ionization technique.

  8. Retinal Oximetry with Scanning Laser Ophthalmoscope in Infants

    PubMed Central

    Vehmeijer, Wouter B.; Magnusdottir, Vigdis; Eliasdottir, Thorunn S.; Hardarson, Sveinn Hakon; Schalij-Delfos, Nicoline E.; Stefánsson, Einar

    2016-01-01

    Purpose Dual wavelength retinal oximetry has been developed for adults, but is not available for infants. Retinal oximetry may provide insight into the pathophysiology of oxygen-mediated diseases like retinopathy of prematurity. More insight in the oxygen metabolism of the retina in infants may provide valuable clues for better understanding and subsequent prevention or treatment of the disease. The measurements of oxygen saturation are obtained with two fundus images simultaneously captured in two different wavelengths of light. The comparison in light absorption of oxygenated and deoxygenated hemoglobin can be used to estimate the oxygen saturation within the retinal vessels by means of a software algorithm. This study aims to make retinal oximetry available for neonates. The first step towards estimating retinal oxygen saturation is determining the optical density ratio. Therefore, the purpose of this study is to image healthy newborn infants with a scanning laser ophthalmoscope and determine the optical density ratio for retinal oximetry analysis. Methods Images of the retina of full-term healthy infants were obtained with an SLO, Optomap 200Tx (Optos), with two laser wavelengths (532nm and 633nm). The infant lay face down on the lower arm of the parent, while the parent supported the chest and chin with one hand, and stabilized the back with the other hand. No mydriatics or eyelid specula were used during this study. The images were analyzed with modified Oxymap Analyzer software for calculation of the Optical Density Ratio (ODR) and vessel width. The ODR is inversely and approximately linearly related to the oxygen saturation. Measurements were included from the superotemporal vessel pair. A paired t-test was used for statistical analysis. Results Fifty-nine infants, (58% female), were included with mean gestational age of 40 ± 1.3 weeks (mean ± SD) and mean post-natal age of 16 ± 4.8 days. A total of 28 images were selected for retinal oximetry analysis

  9. Acousto-optical deflection-based laser beam scanning for fluorescence detection on multichannel electrophoretic microchips.

    PubMed

    Huang, Z; Munro, N; Hühmer, A F; Landers, J P

    1999-12-01

    Laser beam scanning driven by an acousto-optical deflector (AOD) is presented for multimicrochannel laser-induced fluorescence (LIF) detection during microchip-based electrophoresis. While fast laser beam scanning for LIF detection on capillary or microchannel arrays can been achieved with galvanometric scanning or a translating stage, it can also be accomplished by using acoustic waves to deflect the laser beam in a manner that is dependent on the acoustic frequency. AOD scanning differs from other approaches in that no moving parts are required, and the scan frequency is faster than conventional approaches. Using a digital/analog (D/A) converter to provide addressing voltages to a voltage/frequency converter, rapidly changing the frequency input to the AOD allows the laser beam to be addressed accurately on a microchip. With the ability to change the frequency on the nanosecond time scale, scanning rates as high as 30 Hz for Windows-based LabView programming are possible, with much faster scan rates achievable if a microprocessor-embedded system is utilized. In addition to spatial control, temporal control is easily attainable via raster scanning or random addressing, allowing for the scanning process to be self-aligning. Since the D/A output voltages drive the scanning of the laser beam over all channels, the software can define addressing voltages corresponding to the microchannel centers and, subsequently, fluorescence data can be collected from only those locations. This method allows for flexible, high-speed, self-align scanning for fluorescence detection in capillary or microchip electrophoresis and has the potential to be applied to a number of applications.

  10. Clinical applications of in vivo fluorescence confocal laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Oh, Chilhwan; Park, Sangyong; Kim, Junhyung; Ha, Seunghan; Park, Gyuman; Lee, Gunwoo; Lee, Onseok; Chun, Byungseon; Gweon, Daegab

    2008-02-01

    Living skin for basic and clinical research can be evaluated by Confocal Laser Scanning Microscope (CLSM) non-invasively. CLSM imaging system can achieve skin image its native state either "in vivo" or "fresh biopsy (ex vivo)" without fixation, sectioning and staining that is necessary for routine histology. This study examines the potential fluorescent CLSM with a various exogenous fluorescent contrast agent, to provide with more resolution images in skin. In addition, in vivo fluorescent CLSM researchers will be extended a range of potential clinical application. The prototype of our CLSM system has been developed by Prof. Gweon's group. The operating parameters are composed of some units, such as illuminated wavelength 488 nm, argon illumination power up to 20mW on the skin, objective lens, 0.9NA oil immersion, axial resolution 1.0μm, field of view 200μm x 100μm (lateral resolution , 0.3μm). In human volunteer, fluorescein sodium was administrated topically and intradermally. Animal studies were done in GFP transgenic mouse, IRC mouse and pig skin. For imaging of animal skin, fluorescein sodium, acridine orange, and curcumine were used for fluorescein contrast agent. We also used the GFP transgenic mouse for fluorescein CLSM imaging. In intact skin, absorption of fluorescein sodium by individual corneocyte and hair. Intradermal administrated the fluorescein sodium, distinct outline of keratinocyte cell border could be seen. Curcumin is a yellow food dye that has similar fluorescent properties to fluorescein sodium. Acridin Orange can be highlight nuclei in viable keratinocyte. In vivo CLSM of transgenic GFP mouse enable on in vivo, high resolution view of GFP expressing skin tissue. GFP signals are brightest in corneocyte, kertinocyte, hair and eccrine gland. In intact skin, absorption of fluorescein sodium by individual corneocyte and hair. Intradermal administrated the fluorescein sodium, distinct outline of keratinocyte cell border could be seen. In

  11. New method for sperm evaluation by 3-dimensional laser scanning microscopy in different laboratory animal species.

    PubMed

    Weber, Klaus; Waletzky, Alexander; Fendl, Diana; Ordóñez, Patricia; Takawale, Pradeep; Hein, Felix; Riedel, Wolfram; König, Andres; Kunze, Marc; Leoni, Anne-Laure; Rivera, Javier; Quirici, Roberto; Romano, Ivano; Paepke, Susanne; Okazaki, Yoshimasa; Hardisty, Jerry F

    2014-01-01

    Sperm analysis is one of the end points in reproductive toxicology studies. Different methods for quantitative sperm analysis have been described. For qualitative morphological sperm analysis, either such techniques or smears of sperm and histological sperm staging are in use. Any of these methods provides morphological results on a light microscopy level. Laser scanning microscopy is a technique using a focused laser for scanning an object. The Olympus 3D Laser Scanning Microscope LEXT OLS4000 with optional possibilities of differential interference contrast provides a microscopic method for visualizing microasperities, which are far beyond the resolving power of a typical light or laser microscope. This technique was applied to sperm of mice, rats, rabbits, and cynomolgus monkeys at magnifications up to ×17 090. The obtained images are comparable to those of a scanning electron microscope under relatively low-power magnifications. Measurements on sperm parameters were taken by an integrated image analysis software tool. Abnormalities were easily detectable.

  12. CONFOCAL LASER SCANNING MICROSCOPY OF APOPTOSIS IN WHOLE MOUSE AND RAT OVARIES

    EPA Science Inventory

    Confocal Laser Scanning Microscopy of Apoptosis in Whole Mouse and Rat Ovaries. Robert M. Zucker Susan C. Jeffay and Sally D. Perreault Reproductive Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research ...

  13. Airborne Laser Systems Testing and Analysis (essals et analyse des systemes laser embarques)

    DTIC Science & Technology

    2010-04-01

    4 EMT-2 Laser Spot Energy Measurement 5-11 Figure 5-5 PILASTER FRCT Target Construction 5-12 Figure 5-6 PILASTER FXDT Target Layout 5-13 Figure 5... energy has been optically collected, obstacle detection/classification is performed through an analog detection of the echoes and two successive analysis ... analysis (i.e., geometry, energy distribution, time analysis ), for the maximum number of pulses (spots) in a sequence, for the PHOENIX NIR camera; and

  14. Pattern formation and flow control of fine particles by laser-scanning micromanipulation.

    PubMed

    Sasaki, K; Koshioka, M; Misawa, H; Kitamura, N; Masuhara, H

    1991-10-01

    A novel micromanipulation technique is proposed for aligning fine particles on micrometer-scale spatial patterns and for moving the particles continuously along the formed patterns. This technique is based on the repetitive scanning of a focused trapping laser beam. The velocity of the particle flow can be controlled by scan speed and laser power. The origin of the driving force is considered theoretically and experimentally.

  15. Frequency scanning interferometry with nanometer precision using a vertical-cavity surface-emitting laser diode under scanning speed control

    NASA Astrophysics Data System (ADS)

    Kakuma, Seiichi

    2015-12-01

    Frequency scanning interferometry technique with a nanometer precision using a vertical-cavity surface-emitting laser diode (VCSEL) is presented. Since the frequency scanning of the VCSEL is linearized by the phase-locked-loop technique, the gradient of the interference fringe order can be precisely determined using linear least squares fitting. This enables a length measurement with a precision better than a quarter wavelength, and the absolute fringe number including the integer part at the atomic transition spectrum (rubidium-D2 line) is accurately determined. The validity of the method is demonstrated by excellent results of block gauge measurement with a root mean square error better than 5 nm.

  16. Stop-and-Go Mode: Sensor Manipulation as Essential as Sensor Development in Terrestrial Laser Scanning

    PubMed Central

    Lin, Yi; Hyyppä, Juha; Kukko, Antero

    2013-01-01

    This study was dedicated to illustrating the significance of sensor manipulation in the case of terrestrial laser scanning, which is a field now in quick development. In fact, this quickness was mainly rooted in the emergence of new sensors with better performance, while the implications of sensor manipulation have not been fully recognized by the whole community. For this technical gap, the stop-and-go mapping mode can be reckoned as one of the potential solution plans. Stop-and-go was first proposed to handle the low efficiency of traditional static terrestrial laser scanning, and then, it was re-emphasized to improve the stability of sample collections for the state-of-the-art technology of mobile laser scanning. This work reviewed the previous efforts of trying the stop-and-go mode for improving the performance of static and mobile terrestrial laser scanning and generalized their principles respectively. This work also analyzed its advantages compared to the fully-static and fully-kinematic terrestrial laser scanning, and suggested the plans with more automatic measures for raising the efficacy of terrestrial laser scanning. Overall, this literature review indicated that the stop-and-go mapping mode as a case with generic sense can verify the presumption of sensor manipulation as essential as sensor development. PMID:23799493

  17. Stop-and-go mode: sensor manipulation as essential as sensor development in terrestrial laser scanning.

    PubMed

    Lin, Yi; Hyyppä, Juha; Kukko, Antero

    2013-06-25

    This study was dedicated to illustrating the significance of sensor manipulation in the case of terrestrial laser scanning, which is a field now in quick development. In fact, this quickness was mainly rooted in the emergence of new sensors with better performance, while the implications of sensor manipulation have not been fully recognized by the whole community. For this technical gap, the stop-and-go mapping mode can be reckoned as one of the potential solution plans. Stop-and-go was first proposed to handle the low efficiency of traditional static terrestrial laser scanning, and then, it was re-emphasized to improve the stability of sample collections for the state-of-the-art technology of mobile laser scanning. This work reviewed the previous efforts of trying the stop-and-go mode for improving the performance of static and mobile terrestrial laser scanning and generalized their principles respectively. This work also analyzed its advantages compared to the fully-static and fully-kinematic terrestrial laser scanning, and suggested the plans with more automatic measures for raising the efficacy of terrestrial laser scanning. Overall, this literature review indicated that the stop-and-go mapping mode as a case with generic sense can verify the presumption of sensor manipulation as essential as sensor development.

  18. Mobile 3D laser scanning technology application in the surveying of urban underground rail transit

    NASA Astrophysics Data System (ADS)

    Han, Youmei; Yang, Bogang; Zhen, Yinan

    2016-11-01

    Mobile 3D laser scanning technology is one hot kind of digital earth technology. 3D completion surveying is relative new concept in surveying and mapping. A kind of mobile 3D laser scanning system was developed for the urban underground rail 3D completion surveying. According to the characteristics of underground rail environment and the characters of the mobile laser scanning system, it designed a suitable test scheme to improving the accuracy of this kind of mobile laser scanning system when it worked under no GPS signal environment. Then it completed the application of this technology in the No.15 rail 3D completion surveying. Meanwhile a set of production process was made for the 3D completion surveying based on this kind of mobile 3D laser scanning technology. These products were also proved the efficiency of the new technology in the rail 3D completion surveying. Using mobile 3D laser scanning technology to complete underground rail completion surveying has been the first time in China until now. It can provide a reference for 3D measurement of rail completion surveying or the 3D completion surveying of other areas.

  19. Combining terrestrial laser scanning and UAV photogrammetry for fast and lightweight surveying

    NASA Astrophysics Data System (ADS)

    Conforti, Dario

    2015-04-01

    To create detailed and accurate 3D maps of small- to medium-sized areas surveyors often turn to a terrestrial laser scanner (TLS). A TLS can make thousands of lidar measurements per second with centimeter-level accuracy even at long ranges, using scanning mirrors to aim the laser up/down and left/right for full coverage of the target area. One limitation of using a TLS is that complex objects may require many more TLS survey positions than simpler ones. Since protrusions may block line of sight to certain areas that can only be seen from particular angles, surveyors must survey from several additional locations to make sure the entire area is covered. This is particularly true for setups where the scanner cannot be elevated to gain line of sight to all the areas that are required to be surveyed. To resolve this issue, surveyors often turn to aerial survey vehicles. An aerial vehicle's bird's-eye perspective resolves features easily and its mobility lets the surveyor quickly capture the whole survey region from multiple angles. To survey more efficiently, surveyors can combine the strengths of TLS and airborne systems, resulting in a cost-effective method of mapping small- to medium-sized sites with 3D data and imagery. This process uses a standard TLS to survey from a few points around the area of interest, particularly vertical faces that would be difficult to survey from the air. Simultaneously, the surveyor uses a lightweight UAV equipped with a camera, gimbal, and basic GPS receiver to collect photogrammetric imagery over the site. During post-processing, the aerial imagery is processed to create 3D data of its own using automated triangulation software. This aerial 3D data is then merged with the 3D data created by the TLS. The aerial 3D data is discarded where it conflicts with the more precise TLS data, but is used to fill in the gaps in the areas where the TLS could not collect any data at all. Finally, the resultant 3D data is merged with the original

  20. Real-time Data Processing and Visualization for the Airborne Scanning High-resolution Interferometer Sounder (S-HIS)

    NASA Astrophysics Data System (ADS)

    Taylor, J. K.; Revercomb, H. E.; Hoese, D.; Garcia, R. K.; Smith, W. L.; Weisz, E.; Tobin, D. C.; Best, F. A.; Knuteson, R. O.; Sullivan, D. V.; Barnes, C. M.; Van Gilst, D. P.

    2015-12-01

    The Hurricane and Severe Storm Sentinel (HS3) is a five-year NASA mission targeted to enhance the understanding of the formation and evolution of hurricanes in the Atlantic basin. Measurements were made from two NASA Global Hawk Unmanned Aircraft Systems (UAS) during the 2012 through 2014 hurricane seasons, with flights conducted from the NASA Wallops Flight Facility. The Global Hawk aircraft are capable of high altitude flights with durations of up to 30 hours, which allow extensive observations over distant storms, not typically possible with manned aircraft. The two NASA Global Hawks were equipped with instrument suites to study the storm environment, and inner core structure and processes, respectively. The Scanning High-resolution Interferometer Sounder (S-HIS), designed and built by the University of Wisconsin (UW) Space Science and Engineering Center (SSEC), measures emitted thermal radiation at high spectral resolution between 3.3 and 18 microns. The radiance measurements are used to obtain temperature and water vapor profiles of the Earth's atmosphere. The S-HIS spatial resolution is 2 km at nadir, across a 40 km ground swath from a nominal altitude of 20 kilometers. Since 1998, the S-HIS has participated in 33 field campaigns and has proven to be extremely dependable, effective, and highly accurate. It has flown on the NASA ER-2, DC-8, Proteus, WB-57, and Global Hawk airborne platforms. The UW S-HIS infrared sounder instrument is equipped with a real-time ground data processing system capable of delivering atmospheric profiles, radiance data, and engineering status to mission support scientists - all within less than one minute from the time of observation. This ground data processing system was assembled by a small team using existing software and proven practical techniques similar to a satellite ground system architecture. This summary outlines the design overview for the system and illustrates the data path, content, and outcomes.

  1. a New Approach for Segmentation-Based Texturing of Laser Scanning Data

    NASA Astrophysics Data System (ADS)

    Lari, Z.; Habib, A.

    2015-02-01

    In recent years, laser scanning systems have been recognized as a fast and accurate technology for the acquisition of high density spatial data. The advent of these systems has reduced the cost and increased the availability of accurate 3D data for mapping, modelling, and monitoring applications. The original laser scanning data does not explicitly provide meaningful information about the characteristics of the scanned surfaces. Therefore, reliable processing procedures are applied for information extraction from these datasets. However, the derived surfaces through laser scanning data processing cannot be effectively interpreted due to the lack of spectral information. To resolve this problem, a new texturing procedure is introduced in this paper to improve the interpretability of laser scanning-derived surfaces using spectral information from overlapping imagery. In this texturing approach, individual planar regions, derived through a laser scanning data segmentation procedure, are textured using the available imagery. This texturing approach, which aims to overcome the computational inefficiency of the previously-developed point-based texturing techniques, is implemented in three steps. In the first step, the visibility of the segmented planar regions in the available imagery is checked and a list of appropriate images for texturing each planar region is established. An occlusion detection procedure is then performed to identify the parts of the segmented regions which are occluding/being occluded by other regions in the field of view of the utilized images. In the second step, visible parts of planar regions are decomposed into parts which should be textured using individual images. Finally, a rendering procedure is performed to texture these parts using available images. Experimental results from real laser scanning dataset and overlapping imagery demonstrate the feasibility of the proposed approach for texturing laser scanning-derived surfaces using images.

  2. Eye safety analysis for non-uniform retinal scanning laser trajectories

    NASA Astrophysics Data System (ADS)

    Schelinski, Uwe; Dallmann, Hans-Georg; Grüger, Heinrich; Knobbe, Jens; Pügner, Tino; Reinig, Peter; Woittennek, Franziska

    2016-03-01

    Scanning the retinae of the human eyes with a laser beam is an approved diagnosis method in ophthalmology; moreover the retinal blood vessels form a biometric modality for identifying persons. Medical applied Scanning Laser Ophthalmoscopes (SLOs) usually contain galvanometric mirror systems to move the laser spot with a defined speed across the retina. Hence, the load of laser radiation is uniformly distributed and eye safety requirements can be easily complied. Micro machined mirrors also known as Micro Electro Mechanical Systems (MEMS) are interesting alternatives for designing retina scanning systems. In particular double-resonant MEMS are well suited for mass fabrication at low cost. However, their Lissajous-shaped scanning figure requires a particular analysis and specific measures to meet the requirements for a Class 1 laser device, i.e. eye-safe operation. The scanning laser spot causes a non-uniform pulsing radiation load hitting the retinal elements within the field of view (FoV). The relevant laser safety standards define a smallest considerable element for eye-related impacts to be a point source that is visible with an angle of maximum 1.5 mrad. For non-uniform pulsing expositions onto retinal elements the standard requires to consider all particular impacts, i.e. single pulses, pulse sequences in certain time intervals and cumulated laser radiation loads. As it may be expected, a Lissajous scanning figure causes the most critical radiation loads at its edges and borders. Depending on the applied power the laser has to be switched off here to avoid any retinal injury.

  3. Laser scanning confocal microscopy and laser tweezers based experiments to understand dentine-bacteria interactions

    NASA Astrophysics Data System (ADS)

    Peng, Sum Chee; Mohanty, Samarendra; Gupta, P. K.; Kishen, Anil

    2007-02-01

    Failure of endodontic treatment is commonly due to Enterococcal infection. In this study influence of chemical treatments of type-I collagen membrane by chemical agents commonly used in endodontic treatment on Enterococcus faecalis cell adherence was evaluated. In order to determine the change in number of adhering bacteria after chemical treatment, confocal laser scanning microscopy was used. For this, overnight culture of E faecalis in All Culture broth was applied to chemically treated type-I collagen membrane. It was found that Ca(OH) II treated groups had statistically significant (p value=0.05) increase in population of bacteria adherence. The change in adhesion force between bacteria and collagen was determined by using optical tweezers (1064 nm). For this experiment, Type-I collagen membrane was soaked for 5 mins in a media that contained 50% all culture media and 50% saturated Ca(OH) II . The membrane was spread on the coverslip, on which diluted bacterial suspension was added. The force of laser tweezers on the bacteria was estimated at different trap power levels using viscous drag method and trapping stiffness was calculated using Equipartition theorem method. Presence of Ca(OH) II was found to increase the cell-substrate adherence force from 0.38pN to >2.1pN. Together, these experiments show that it was highly probable that the increase in adherence to collagen was due to a stronger adhesion in the presence of Ca (OH) II.

  4. Spatial coherence measurement of a scanning laser system and applicability of the Zernike's approximation to the exit pupil on the scan mirror

    NASA Astrophysics Data System (ADS)

    Kubota, Shigeo

    2012-11-01

    Spatial coherence of the scanning laser beam was observed on the Young's experimental set up using 50-μm-wide, 200-μm-separation double slits, which measured the less than unity fringe visibility in the Fraunhofer diffraction pattern of the double slits illuminated by the scanning laser beam at horizontal scan frequency 21 kHz, while approximately unity in case of the illumination by the laser beam at rest. This fact allow us to use the Zernike's approximation when applying the van Cittert Zernike theorem to the scanning laser system such as the laser pico-projectors in order to estimate its speckle contrast in the projected image on the screen diffuser. The predicted and measured speckle contrasts showed excellent agreement on the screen illuminated by the laser projector.

  5. SCAN+

    SciTech Connect

    Kenneth Krebs, John Svoboda

    2009-11-01

    SCAN+ is a software application specifically designed to control the positioning of a gamma spectrometer by a two dimensional translation system above spent fuel bundles located in a sealed spent fuel cask. The gamma spectrometer collects gamma spectrum information for the purpose of spent fuel cask fuel loading verification. SCAN+ performs manual and automatic gamma spectrometer positioning functions as-well-as exercising control of the gamma spectrometer data acquisitioning functions. Cask configuration files are used to determine the positions of spent fuel bundles. Cask scanning files are used to determine the desired scan paths for scanning a spent fuel cask allowing for automatic unattended cask scanning that may take several hours.

  6. Multi-frequency, 3D ODS measurement by continuous scan laser Doppler vibrometry

    NASA Astrophysics Data System (ADS)

    Weekes, Ben; Ewins, David

    2015-06-01

    Continuous scan laser Doppler vibrometry (CSLDV) is a technique which has been described and explored in the literature for over two decades, but remains niche compared to SLDV inspection by a series of discrete-point measurements. This is in part because of the unavoidable phenomenon of laser speckle, which deteriorates signal quality when velocity data is captured from a moving spot measurement. Further, applicability of CSLDV has typically been limited to line scans and rectangular areas by the application of sine, step, or ramp functions to the scanning mirrors which control the location of the measurement laser spot. In this paper it is shown that arbitrary functions to scan any area can easily be derived from a basic calibration routine, equivalent to the calibration performed in conventional discrete-point laser vibrometry. This is extended by performing the same scan path upon a test surface from three independent locations of the laser head, and decomposing the three sets of one-dimensional deflection shapes into a single set of three-dimensional deflection shapes. The test was performed with multi-sine excitation, yielding 34 operating deflection shapes from each scan.

  7. Automatic Stem Mapping by Merging Several Terrestrial Laser Scans at the Feature and Decision Levels

    PubMed Central

    Liang, Xinlian; Hyyppä, Juha

    2013-01-01

    Detailed up-to-date ground reference data have become increasingly important in quantitative forest inventories. Field reference data are conventionally collected at the sample plot level by means of manual measurements, which are both labor-intensive and time-consuming. In addition, the number of attributes collected from the tree stem is limited. More recently, terrestrial laser scanning (TLS), using both single-scan and multi-scan techniques, has proven to be a promising solution for efficient stem mapping at the plot level. In the single-scan method, the laser scanner is placed at the center of the plot, creating only one scan, and all trees are mapped from the single-scan point cloud. Consequently, the occlusion of stems increases as the range of the scanner increases, depending on the forest's attributes. In the conventional multi-scan method, several scans are made simultaneously inside and outside of the plot to collect point clouds representing all trees within the plot, and these scans are accurately co-registered by using artificial reference targets manually placed throughout the plot. The additional difficulty of applying the multi-scan method is due to the point-cloud registration of several scans not being fully automated yet. This paper proposes a multi-single-scan (MSS) method to map the sample plot. The method does not require artificial reference targets placed on the plot or point-level registration. The MSS method is based on the fully automated processing of each scan independently and on the merging of the stem positions automatically detected from multiple scans to accurately map the sample plot. The proposed MSS method was tested on five dense forest plots. The results show that the MSS method significantly improves the stem-detection accuracy compared with the single-scan approach and achieves a mapping accuracy similar to that achieved with the multi-scan method, without the need for the point-level registration. PMID:23353143

  8. Nano-strip grating lines self-organized by a high speed scanning CW laser

    NASA Astrophysics Data System (ADS)

    Kaneko, Satoru; Ito, Takeshi; Akiyama, Kensuke; Yasui, Manabu; Kato, Chihiro; Tanaka, Satomi; Hirabayashi, Yasuo; Mastuno, Akira; Nire, Takashi; Funakubo, Hiroshi; Yoshimoto, Mamoru

    2011-04-01

    After a laser annealing experiment on Si wafer, we found an asymmetric sheet resistance on the surface of the wafer. Periodic nano-strip grating lines (nano-SGLs) were self-organized along the trace of one-time scanning of the continuous wave (CW) laser. Depending on laser power, the nano-trench formed with a period ranging from 500 to 800 nm with a flat trough between trench structures. This simple method of combining the scanning laser with high scanning speed of 300 m min - 1 promises a large area of nanostructure fabrication with a high output. As a demonstration of the versatile method, concentric circles were drawn on silicon substrate rotated by a personal computer (PC) cooling fan. Even with such a simple system, the nano-SGL showed iridescence from the concentric circles.

  9. Note: Laser beam scanning using a ferroelectric liquid crystal spatial light modulator

    SciTech Connect

    Das, Abhijit; Boruah, Bosanta R.

    2014-04-15

    In this work we describe laser beam scanning using a ferroelectric liquid crystal spatial light modulator. Commercially available ferroelectric liquid crystal spatial light modulators are capable of displaying 85 colored images in 1 s using a time dithering technique. Each colored image, in fact, comprises 24 single bit (black and white) images displayed sequentially. We have used each single bit image to write a binary phase hologram. For a collimated laser beam incident on the hologram, one of the diffracted beams can be made to travel along a user defined direction. We have constructed a beam scanner employing the above arrangement and demonstrated its use to scan a single laser beam in a laser scanning optical sectioning microscope setup.

  10. Distance measurement using frequency scanning interferometry with mode-hoped laser

    NASA Astrophysics Data System (ADS)

    Medhat, M.; Sobee, M.; Hussein, H. M.; Terra, O.

    2016-06-01

    In this paper, frequency scanning interferometry is implemented to measure distances up to 5 m absolutely. The setup consists of a Michelson interferometer, an external cavity tunable diode laser, and an ultra-low expansion (ULE) Fabry-Pérot (FP) cavity to measure the frequency scanning range. The distance is measured by acquiring simultaneously the interference fringes from, the Michelson and the FP interferometers, while scanning the laser frequency. An online fringe processing technique is developed to calculate the distance from the fringe ratio while removing the parts result from the laser mode-hops without significantly affecting the measurement accuracy. This fringe processing method enables accurate distance measurements up to 5 m with measurements repeatability ±3.9×10-6 L. An accurate translation stage is used to find the FP cavity free-spectral-range and therefore allow accurate measurement. Finally, the setup is applied for the short distance calibration of a laser distance meter (LDM).

  11. A building extraction approach for Airborne Laser Scanner data utilizing the Object Based Image Analysis paradigm

    NASA Astrophysics Data System (ADS)

    Tomljenovic, Ivan; Tiede, Dirk; Blaschke, Thomas

    2016-10-01

    In the past two decades Object-Based Image Analysis (OBIA) established itself as an efficient approach for the classification and extraction of information from remote sensing imagery and, increasingly, from non-image based sources such as Airborne Laser Scanner (ALS) point clouds. ALS data is represented in the form of a point cloud with recorded multiple returns and intensities. In our work, we combined OBIA with ALS point cloud data in order to identify and extract buildings as 2D polygons representing roof outlines in a top down mapping approach. We performed rasterization of the ALS data into a height raster for the purpose of the generation of a Digital Surface Model (DSM) and a derived Digital Elevation Model (DEM). Further objects were generated in conjunction with point statistics from the linked point cloud. With the use of class modelling methods, we generated the final target class of objects representing buildings. The approach was developed for a test area in Biberach an der Riß (Germany). In order to point out the possibilities of the adaptation-free transferability to another data set, the algorithm has been applied "as is" to the ISPRS Benchmarking data set of Toronto (Canada). The obtained results show high accuracies for the initial study area (thematic accuracies of around 98%, geometric accuracy of above 80%). The very high performance within the ISPRS Benchmark without any modification of the algorithm and without any adaptation of parameters is particularly noteworthy.

  12. Axial scanning laser Doppler velocimeter using wavelength change without moving mechanism in sensor probe.

    PubMed

    Maru, Koichi

    2011-03-28

    A scanning laser Doppler velocimeter (LDV) without any moving mechanism in its sensor probe is proposed. In the proposed scanning LDV, the measurement position is axially scanned by change in the wavelength of the light input to the sensor probe, instead of using a moving mechanism in the sensor probe. For this purpose, a tunable laser and diffraction gratings are used, and the sensor probe including the gratings is separated from the main body including the tunable laser. To demonstrate the scanning function based on the proposed concept, an experiment was conducted using optical fibers, a commercial tunable laser and a setup of the sensor probe consisting of bulk optical components. As the experimental result, it is found that the measurement positions estimated from the measured beat frequencies are in good agreement with the theoretical values. The scan ranges over a wavelength range of 30 nm are estimated to be 29.3 mm when the beam angle to the measurement position at the wavelength of 1540 nm is 10° and 20.8 mm when the beam angle is 15°. The result indicates that the scanning function by means of changing the wavelength input to the sensor probe is successfully demonstrated for the first time. The proposed method has the potential for realizing a scanning LDV with a simple, compact and reliable sensor probe.

  13. Laser transmission welding of Clearweld-coated polyethylene glycol terephthalate by incremental scanning technique

    NASA Astrophysics Data System (ADS)

    Wang, Y. Y.; Wang, A. H.; Weng, Z. K.; Xia, H. B.

    2016-06-01

    Transmission laser welding using Incremental Scanning Technique(TWIST) mode and conventional contour welding mode were adopted to investigate laser transmission welding of 0.5 mm thick PET plate. A 1064 nm fiber laser was used to weld PET at the (TWIST) mode, and an 808 nm diode laser was applied to conduct the conventional contour welding. The Clearweld coating was used as laser absorbing material. The influences of laser parameters (i.e. defocusing distance, distance between two circles) on the quality of weld seams were analyzed by optical microscopy. Moreover, geometry and shear strength of the weld zone were tested to optimize laser parameters. Additionally, the water vapor permeability (WVP) of weld seams was measured to test hermetical capacity. Results show that the shear strength and hermetic capacity of weld seam by TWIST mode are at the same level in comparison with that of the conventional contour welding.

  14. Angle extended linear MEMS scanning system for 3D laser vision sensor

    NASA Astrophysics Data System (ADS)

    Pang, Yajun; Zhang, Yinxin; Yang, Huaidong; Zhu, Pan; Gai, Ye; Zhao, Jian; Huang, Zhanhua

    2016-09-01

    Scanning system is often considered as the most important part for 3D laser vision sensor. In this paper, we propose a method for the optical system design of angle extended linear MEMS scanning system, which has features of huge scanning degree, small beam divergence angle and small spot size for 3D laser vision sensor. The principle of design and theoretical formulas are derived strictly. With the help of software ZEMAX, a linear scanning optical system based on MEMS has been designed. Results show that the designed system can extend scanning angle from ±8° to ±26.5° with a divergence angle small than 3.5 mr, and the spot size is reduced for 4.545 times.

  15. Evolution of MEMS scanning mirrors for laser projection in compact consumer electronics

    NASA Astrophysics Data System (ADS)

    Tauscher, Jason; Davis, Wyatt O.; Brown, Dean; Ellis, Matt; Ma, Yunfei; Sherwood, Michael E.; Bowman, David; Helsel, Mark P.; Lee, Sung; Coy, John Wyatt

    2010-02-01

    The applicability of MOEMS scanning mirrors towards the creation of "flying spot" scanned laser displays is well established. The extension of this concept towards compact embedded pico-projectors has required an evolution of scanners and packaging to accommodate the needs of the consumer electronics space. This paper describes the progression of the biaxial MOEMS scanning mirrors developed by Microvision over recent years. Various aspects of the individual designs are compared. Early devices used a combination of magnetic quasistatic actuation and resonant electrostatic operation in an evacuated atmosphere to create a projection engine for retinal scanned displays. Subsequent designs realized the elimination of both the high voltage electrostatic drive and the vacuum package, and a simplification of the actuation scheme through proprietary technical advances. Additional advances have doubled the scan angle capability and greatly miniaturized the MOEMS component while not incurring significant increase in power consumption, making it an excellent fit for the consumer pico-projector application. The simplicity of the scanned laser-based pico-projector optical design enables high resolution and a large effective image size in a thin projection engine, all of which become critical both to the viability of the technology and adoption by consumers. Microvision's first scanned laser pico-projector is built around a MOEMS scanning mirror capable of projecting 16:9 aspect ratio, WVGA display within a 6.6 mm high package. Further evolution on this path promises continued improvement in resolution, size, and power.

  16. Simulations of an airborne laser absorption spectrometer for atmospheric CO2 measurements

    NASA Astrophysics Data System (ADS)

    Lin, B.; Ismail, S.; Harrison, F. W.; Browell, E. V.; Dobler, J. T.; Refaat, T.; Kooi, S. A.

    2012-12-01

    Atmospheric column amount of carbon dioxide (CO2), a major greenhouse gas of the atmosphere, has significantly increased from a preindustrial value of about 280 parts per million (ppm) to more than 390 ppm at present. Our knowledge about the spatiotemporal change and variability of the greenhouse gas, however, is limited. Thus, a near-term space mission of the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) is crucial to increase our understanding of global sources and sinks of CO2. Currently, NASA Langley Research Center (LaRC) and ITT Exelis are jointly developing and testing an airborne laser absorption spectrometer (LAS) as a prototype instrument for the mission. To assess the space capability of accurate atmospheric CO2 measurements, accurate modeling of the instrument and practical evaluation of space applications are the keys for the success of the ASCENDS mission. This study discusses the simulations of the performance of the airborne instrument and its CO2 measurements. The LAS is a multi-wavelength spectrometer operating on a 1.57 um CO2 absorption line. The Intensity-Modulated Continuous-Wave (IM-CW) approach is implemented in the instrument. To reach accurate CO2 measurements, transmitted signals are monitored internally as reference channels. A model of this kind of instrument includes all major components of the spectrometer, such as modulation generator, fiber amplifier, telescope, detector, transimpedance amplifier, matched filter, and other signal processors. The characteristics of these components are based on actual laboratory tests, product specifications, and general understanding of the functionality of the components. For simulations of atmospheric CO2 measurements, environmental conditions related to surface reflection, atmospheric CO2 and H2O profiles, thin clouds, and aerosol layers, are introduced into the model. Furthermore, all major noise sources such as those from detectors, background radiation, speckle, and

  17. A custom CMOS imager for multi-beam laser scanning microscopy and an improvement of scanning speed

    NASA Astrophysics Data System (ADS)

    Seo, Min-Woong; Kagawa, Keiichiro; Yasutomi, Keita; Kawahito, Shoji

    2013-02-01

    Multi-beam laser scanning confocal microscopy with a 256 × 256-pixel custom CMOS imager performing focal-plane pinhole effect, in which any rotating disk is not required, is demonstrated. A specimen is illuminated by 32 × 32 diffraction limited light spots whose wavelength and pitch are 532nm and 8.4 μm, respectively. The spot array is generated by a microlens array, which is scanned by two-dimensional piezo actuator according to the scanning of the image sensor. The frame rate of the prototype is 0.17 Hz, which is limited by the actuator. The confocal effect has been confirmed by comparing the axial resolution in the confocal imaging mode with that of the normal imaging mode. The axial resolution in the confocal mode measured by the full width at half maximum (FWHM) for a planar mirror was 8.9 μm, which is showed that the confocality has been achieved with the proposed CMOS image sensor. The focal-plane pinhole effect in the confocal microscopy with the proposed CMOS imager has been demonstrated at low frame rate. An improvement of the scanning speed and a CMOS imager with photo-sensitivity modulation pixels suitable for high-speed scanning are also discussed.

  18. Laser scanning methods and a phase comparison, modulated laser range finder for terrain sensing on a Mars roving vehicle. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Herb, G. T.

    1973-01-01

    Two areas of a laser range finder for a Mars roving vehicle are investigated: (1) laser scanning systems, and (2) range finder methods and implementation. Several ways of rapidly scanning a laser are studied. Two digital deflectors and a matrix of laser diodes, are found to be acceptable. A complete range finder scanning system of high accuracy is proposed. The problem of incident laser spot distortion on the terrain is discussed. The instrumentation for a phase comparison, modulated laser range finder is developed and sections of it are tested.

  19. Real-Time Analysis of Individual Airborne Microparticles Using Laser Ablation Mass Spectroscopy and Genetically Trained Neural Networks

    SciTech Connect

    Parker, E.P.; Rosenthal, S.E.; Trahan, M.W.; Wagner, J.S.

    1999-01-22

    We are developing a method for analysis of airborne microparticles based on laser ablation of individual molecules in an ion trap mass spectrometer. Airborne particles enter the spectrometer through a differentially-pumped inlet, are detected by light scattered from two CW laser beams, and sampled by a pulsed excimer laser as they pass through the center of the ion trap electrodes. After the laser pulse, the stored ions are separated by conventional ion trap methods. The mass spectra are then analyzed using genetically-trained neural networks (NNs). A number of mass spectra are averaged to obtain training cases which contain a recognizable spectral signature. Averaged spectra for a bacteria and a non-bacteria are shown to the NNs, the response evaluated, and the weights of the connections between neurodes adjusted by a Genetic Algorithm (GA) such that the output from the NN ranges from 0 for non-bacteria to 1 for bacteria. This process is iterated until the population of the GA converges or satisfies predetermined stopping criteria. Using this type of bipolar training we have obtained generalizing NNs able to distinguish five new bacteria from five new non-bacteria, none of which were used in training the NN.

  20. A High-altitude, Advanced-technology Scanning Laser Altimeter for the Elevation for the Nation Program

    NASA Astrophysics Data System (ADS)

    Harding, D. J.

    2007-12-01

    In January of this year the National Research Council's Committee on Floodplain Mapping Technologies recommended to Congress that an Elevation for the Nation program be initiated to enable modernization of the nation's floodplain maps and to support the many other nationwide programs reliant on high-accuracy elevation data. Their recommendation is to acquire a national, high-resolution, seamless, consistent, public-domain, elevation data set created using airborne laser swath mapping (ALSM). Although existing commercial ALSM assets can acquire elevation data of sufficient accuracy, achieving nationwide consistency in a cost-effective manner will be a challenge employing multiple low-flying commercial systems conducting local to regional mapping. This will be particularly true in vegetated terrain where reproducible measurements of ground topography and vegetation structure are required for change-detection purposes. An alternative approach using an advanced technology, wide-swath, high-altitude laser altimeter is described here, based on the Swath Imaging Multi-polarization Photon-counting Lidar (SIMPL) under development via funding from NASA's Instrument Incubator Program. The approach envisions a commercial, federal agency and state partnership, with the USGS providing program coordination, NASA implementing the advanced technology instrumentation, the commercial sector conducting data collection and processing and states defining map product requirements meeting their specific needs. An Instrument Synthesis and Analysis (ISAL) study conducted at Goddard Space Flight Center evaluated an instrument compliment deployed on a long-range Gulfstream G550 platform operating at 12 km altitude. The English Electric Canberra is an alternative platform also under consideration. Instrumentation includes a scanning, multi-beam laser altimeter that maps a 10 km wide swath, IMU and Star Trackers for attitude determination, JPL's Global Differential GPS implementation for

  1. The probability of laser caused ocular injury to the aircrew of undetected aircraft violating the exclusion zone about the airborne aura LIDAR.

    SciTech Connect

    Augustoni, Arnold L.

    2006-12-01

    The probability of a laser caused ocular injury, to the aircrew of an undetected aircraft entering the exclusion zone about the AURA LIDAR airborne platform with the possible violation of the Laser Hazard Zone boundary, was investigated and quantified for risk analysis and management.

  2. Three-Dimensional Laser Scanning for Geometry Documentation and Construction Management of Highway Tunnels during Excavation

    PubMed Central

    Gikas, Vassilis

    2012-01-01

    Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered. PMID:23112655

  3. Compensation of temporal and spatial dispersion for multiphoton acousto-optic laser-scanning microscopy

    NASA Astrophysics Data System (ADS)

    Iyer, Vijay; Saggau, Peter

    2003-10-01

    In laser-scanning microscopy, acousto-optic (AO) deflection provides a means to quickly position a laser beam to random locations throughout the field-of-view. Compared to conventional laser-scanning using galvanometer-driven mirrors, this approach increases the frame rate and signal-to-noise ratio, and reduces time spent illuminating sites of no interest. However, random-access AO scanning has not yet been combined with multi-photon microscopy, primarily because the femtosecond laser pulses employed are subject to significant amounts of both spatial and temporal dispersion upon propagation through common AO materials. Left uncompensated, spatial dispersion reduces the microscope"s spatial resolution while temporal dispersion reduces the multi-photon excitation efficacy. In previous work, we have demonstrated, 1) the efficacy of a single diffraction grating scheme which reduces the spatial dispersion at least 3-fold throughout the field-of-view, and 2) the use of a novel stacked-prism pre-chirper for compensating the temporal dispersion of a pair of AODs using a shorter mechanical path length (2-4X) than standard prism-pair arrangements. In this work, we demonstrate for the first time the use of these compensation approaches with a custom-made large-area slow-shear TeO2 AOD specifically suited for the development of a high-resolution 2-D random-access AO scanning multi-photon laser-scanning microscope (AO-MPLSM).

  4. Recommendations for the design and the installation of large laser scanning microscopy systems

    NASA Astrophysics Data System (ADS)

    Helm, P. Johannes

    2012-03-01

    Laser Scanning Microscopy (LSM) has since the inventions of the Confocal Scanning Laser Microscope (CLSM) and the Multi Photon Laser Scanning Microscope (MPLSM) developed into an essential tool in contemporary life science and material science. The market provides an increasing number of turn-key and hands-off commercial LSM systems, un-problematic to purchase, set up and integrate even into minor research groups. However, the successful definition, financing, acquisition, installation and effective use of one or more large laser scanning microscopy systems, possibly of core facility character, often requires major efforts by senior staff members of large academic or industrial units. Here, a set of recommendations is presented, which are helpful during the process of establishing large systems for confocal or non-linear laser scanning microscopy as an effective operational resource in the scientific or industrial production process. Besides the description of technical difficulties and possible pitfalls, the article also illuminates some seemingly "less scientific" processes, i.e. the definition of specific laboratory demands, advertisement of the intention to purchase one or more large systems, evaluation of quotations, establishment of contracts and preparation of the local environment and laboratory infrastructure.

  5. Three-dimensional laser scanning for geometry documentation and construction management of highway tunnels during excavation.

    PubMed

    Gikas, Vassilis

    2012-01-01

    Driven by progress in sensor technology, computer software and data processing capabilities, terrestrial laser scanning has recently proved a revolutionary technique for high accuracy, 3D mapping and documentation of physical scenarios and man-made structures. Particularly, this is of great importance in the underground space and tunnel construction environment as surveying engineering operations have a great impact on both technical and economic aspects of a project. This paper discusses the use and explores the potential of laser scanning technology to accurately track excavation and construction activities of highway tunnels. It provides a detailed overview of the static laser scanning method, its principles of operation and applications for tunnel construction operations. Also, it discusses the planning, execution, data processing and analysis phases of laser scanning activities, with emphasis given on geo-referencing, mesh model generation and cross-section extraction. Specific case studies are considered based on two construction sites in Greece. Particularly, the potential of the method is examined for checking the tunnel profile, producing volume computations and validating the smoothness/thickness of shotcrete layers at an excavation stage and during the completion of excavation support and primary lining. An additional example of the use of the method in the geometric documentation of the concrete lining formwork is examined and comparisons against dimensional tolerances are examined. Experimental comparisons and analyses of the laser scanning method against conventional surveying techniques are also considered.

  6. Image distortion and its correction in linear galvanometric mirrors-based laser-scanning microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Wenbo; Wu, Zhenguo; Zeng, Haishan

    2015-05-01

    To simplify imaging focusing and calibration tasks, a laser-scanning microscope needs to scan at a moderate frame rate. The inertia of a galvanometric scanner leads to time delays when following external commands, which subsequently introduces image distortions that deteriorate as scan frequency increases. Sinusoidal and triangular waveforms were examined as fast axis driving patterns. The interplay among driving pattern, frequency, sampling rate, phase shift, linear scanning range, and their effect on reconstructed images was discussed. Utilizing position feedback from the linear galvo scanners, the effect of response time could be automatically compensated in real time. Precompensated triangular driving waveform offered the least amount of image distortion.

  7. Experimental validation of a newly designed 6 degrees of freedom scanning laser head: application to three-dimensional beam structure.

    PubMed

    Di Maio, D; Copertaro, E

    2013-12-01

    A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure.

  8. Experimental validation of a newly designed 6 degrees of freedom scanning laser head: Application to three-dimensional beam structure

    NASA Astrophysics Data System (ADS)

    Di Maio, D.; Copertaro, E.

    2013-12-01

    A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure.

  9. Experimental validation of a newly designed 6 degrees of freedom scanning laser head: Application to three-dimensional beam structure

    SciTech Connect

    Di Maio, D.; Copertaro, E.

    2013-12-15

    A new scanning laser head is designed to use single Laser Doppler Vibrometer (LDV) for performing measurements up to 6 degrees of freedom (DOF) at a target. The scanning head is supported by a rotating hollow shaft, which allows the laser beam to travel up to the scanning head from an opposite direction where an LDV is set up. The scanning head is made of a set of two mirrors, which deflects the laser beam with an angle so that the rotation of the scanning head produces a conical scan. When measurements are performed at the focal point of the conical scan then three translational vibration components can be measured, otherwise the very small circle scan, before and after the focal point, can measure up to 6 degrees of freedom, including three translations and three rotations. This paper presents the 6DOF scanning head and the measurements of 3D operational deflection shapes of a test structure.

  10. A 3-d laser scanning system and scan data processing method for the monitoring of tunnel deformations

    NASA Astrophysics Data System (ADS)

    Chmelina, Klaus; Jansa, Josef; Hesina, Gerd; Traxler, Christoph

    2012-11-01

    The paper presents the mobile multi-sensor system Orthos Plus for the monitoring and mapping of tunnel walls, a scan data processing method for the evaluation of 3-d tunnel wall displacements from subsequent wall scans and, finally, a virtual reality tool supporting the interpretation of data. The measuring system consists of a 3-d laser scanner, a motorised total station and a digital camera that are integrated on a light metal frame that is installed on a mobile platform. It has been designed to perform tunnel measurements most efficiently and to meet the special requirements of tunnels under construction. The evaluation of 3-d displacements is based on a 3-d matching algorithm that takes advantage of the particular conditions of tunnel (shotcrete) surfaces. The virtual reality tool allows viewing of data in a 3-d virtual reality tunnel model and their animation in time and space in order supports understanding in an optimal way. The measuring system Orthos Plus has been developed in the course of a national research project, the 3-d matching method in the frame of the Austrian Christian Doppler Laboratory Spatial Data from Laser Scanning and Remote Sensing and the VR tool in the Austrian COMET K1 Competence Center VRVis Center (www.vrvis.at).

  11. Shining new light on braided rivers: capturing grain-to-reach scale morphodynamics with terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Brasington, J.; Williams, R. D.; Vericat, D.; Hicks, M.; Goodsell, B.

    2011-12-01

    The last decade has witnessed a technological revolution in the acquisition of geospatial data. These developments have profound implications for the practice of river science, creating a step-change in the dimensionality, resolution and precision of measurement of fluvial forms and processes. The pace of change has been remarkable; typical datasets of channel geometry have grown from cross-sections containing a few hundred survey observations, to airborne lidar surveys incorporating millions of points. With wide-area terrestrial laser scans comprising tens of billions observations now set to emerge, our data perspectives have been expanded by seven orders of magnitude. Such rapid modernization brings with it new challenges and necessitates the development of novel data management strategies, original algorithms to process dense 3d data, higher dimensional spatial metrics and innovative simulation methods to make optimal use of this rich vein of information. In this paper we describe a field-to-product methodology which aims to address these challenges and has been used to generate an unparalleled dataset capturing the morphological evolution of a labile gravel-bed braided river through a continuous sequence of floods between Oct 2009 and May 2010. These data were generated using a data-fusion approach that combines close-range terrestrial laser scanning with bathymetric data derived from non-metric aerial photography. Surveys were acquired over a 2.5 x 0.7 km reach of the Rees River; a piedmont braided system draining a highland catchment of Southern Alps of NZ. During a 10 month field campaign through the summer flood season, this study reach was resurveyed systematically after each competent flood event. Multi-scale DEMs were derived that capture the spatial distribution of facies and morphological changes at high precision. Results indicate that over 80% of the reach was subject to significant erosion or deposition, with a complex pattern of response to the

  12. MEMS scanning laser projection based on high-Q vacuum packaged 2D-resonators

    NASA Astrophysics Data System (ADS)

    Hofmann, U.; Eisermann, C.; Quenzer, H.-J.; Janes, J.; Schroeder, C.; Schwarzelbach, O.; Jensen, B.; Ratzmann, L.; Giese, T.; Senger, F.; Hagge, J.; Weiss, M.; Wagner, B.; Benecke, W.

    2011-03-01

    Small size, low power consumption and the capability to produce sharp images without need of an objective make MEMS scanning laser based pico-projectors an attractive solution for embedded cell-phone projection displays. To fulfil the high image resolution demands the MEMS scanning mirror has to show large scan angles, a large mirror aperture size and a high scan frequency. An additional important requirement in pico-projector applications is to minimize power consumption of the MEMS scanner to enable a long video projection time. Typically high losses in power are caused by gas damping. For that reason Fraunhofer ISIT has established a fabrication process for 2D-MEMS mirrors that includes vacuum encapsulation on 8-inch wafers. Quality factors as high as 145,000 require dedicated closed loop phase control electronics to enable stable image projection even at rapidly changing laser intensities. A capacitive feedback signal is the basis for controlling the 2D MEMS oscillation and for synchronising the laser sources. This paper reports on fabrication of two-axis wafer level vacuum packaged scanning micromirrors and its use in a compact laser projection display. The paper presents different approaches of overcoming the well-known reflex problem of packaged MEMS scanning mirrors.

  13. Finite element simulation of laser tube bending: Effect of scanning schemes on bending angle, distortions and stress distribution

    NASA Astrophysics Data System (ADS)

    Safdar, Shakeel; Li, Lin; Sheikh, M. A.; Zhu Liu

    2007-09-01

    Laser forming has received considerable attention in recent years. Within laser forming, tube bending is an important industrial activity, with applications in critical engineering systems like micro-machines, heat exchangers, hydraulic systems, boilers, etc. Laser tube bending utilizes the thermal stresses generated during laser scanning to achieve the desired bends. The parameters to control the process are usually laser power, beam diameter, scanning velocity and number of scans. Recently axial scanning has been used for tube bending instead of commonly used circumferential scans. However the comparison between the scanning schemes has involved dissimilar laser beam geometries with circular beam used for circumferential scanning and a rectangular beam for the axial scan. Thermal stresses generated during laser scanning are strongly dependent upon laser beam geometry and scanning direction and hence it is difficult to isolate the contribution made by these two variables. It has recently been established at the Corrosion and Protection Centre, University of Manchester, that corrosion properties of material during laser forming are affected by the number of laser passes. Depending on the material, the corrosion behaviour is either adversely or favourably affected by number of passes. Thus it is of great importance to know how different scanning schemes would affect laser tube bending. Moreover, any scanning scheme which results in greater bending angle would eliminate the need for higher number of passes, making the process faster. However, it is not only the bending angle which is critical, distortions in other planes are also extremely important. Depending on the use of the final product, unwanted distortions may be the final selection criteria. This paper investigates the effect of scanning direction on laser tube bending. Finite-element modelling has been used for the study of the process with some results also validated by experiments.

  14. Mobile laser scanning applied to the earth sciences

    USGS Publications Warehouse

    Brooks, Benjamin A.; Glennie, Craig; Hudnut, Kenneth W.; Ericksen, Todd; Hauser, Darren

    2013-01-01

    Lidar (light detection and ranging), a method by which the precise time of flight of emitted pulses of laser energy is measured and converted to distance for reflective targets, has helped scientists make topographic maps of Earth's surface at scales as fine as centimeters. These maps have allowed the discovery and analysis of myriad otherwise unstudied features, such as fault scarps, river channels, and even ancient ruins [Glennie et al., 2013b].

  15. Laser scanning confocal microscope with programmable amplitude, phase, and polarization of the illumination beam.

    PubMed

    Boruah, B R; Neil, M A A

    2009-01-01

    We describe the design and construction of a laser scanning confocal microscope with programmable beam forming optics. The amplitude, phase, and polarization of the laser beam used in the microscope can be controlled in real time with the help of a liquid crystal spatial light modulator, acting as a computer generated hologram, in conjunction with a polarizing beam splitter and two right angled prisms assembly. Two scan mirrors, comprising an on-axis fast moving scan mirror for line scanning and an off-axis slow moving scan mirror for frame scanning, configured in a way to minimize the movement of the scanned beam over the pupil plane of the microscope objective, form the XY scan unit. The confocal system, that incorporates the programmable beam forming unit and the scan unit, has been implemented to image in both reflected and fluorescence light from the specimen. Efficiency of the system to programmably generate custom defined vector beams has been demonstrated by generating a bottle structured focal volume, which in fact is the overlap of two cross polarized beams, that can simultaneously improve both the lateral and axial resolutions if used as the de-excitation beam in a stimulated emission depletion confocal microscope.

  16. Combining laser scan and photogrammetry for 3D object modeling using a single digital camera

    NASA Astrophysics Data System (ADS)

    Xiong, Hanwei; Zhang, Hong; Zhang, Xiangwei

    2009-07-01

    In the fields of industrial design, artistic design and heritage conservation, physical objects are usually digitalized by reverse engineering through some 3D scanning methods. Laser scan and photogrammetry are two main methods to be used. For laser scan, a video camera and a laser source are necessary, and for photogrammetry, a digital still camera with high resolution pixels is indispensable. In some 3D modeling tasks, two methods are often integrated to get satisfactory results. Although many research works have been done on how to combine the results of the two methods, no work has been reported to design an integrated device at low cost. In this paper, a new 3D scan system combining laser scan and photogrammetry using a single consumer digital camera is proposed. Nowadays there are many consumer digital cameras, such as Canon EOS 5D Mark II, they usually have features of more than 10M pixels still photo recording and full 1080p HD movie recording, so a integrated scan system can be designed using such a camera. A square plate glued with coded marks is used to place the 3d objects, and two straight wood rulers also glued with coded marks can be laid on the plate freely. In the photogrammetry module, the coded marks on the plate make up a world coordinate and can be used as control network to calibrate the camera, and the planes of two rulers can also be determined. The feature points of the object and the rough volume representation from the silhouettes can be obtained in this module. In the laser scan module, a hand-held line laser is used to scan the object, and the two straight rulers are used as reference planes to determine the position of the laser. The laser scan results in dense points cloud which can be aligned together automatically through calibrated camera parameters. The final complete digital model is obtained through a new a patchwise energy functional method by fusion of the feature points, rough volume and the dense points cloud. The design

  17. Diode-laser based scanning laser thermoelectric microscope for thermal diffusivity characterization of thin films on semiconductor substrates

    SciTech Connect

    Borca-Tasciuc, T.; Chen, G.

    1999-07-01

    This work presents new experimental results in the characterization of thermophysical properties for dielectric thin films on semiconductor substrates using the Scanning Laser Thermoelectric Microscope (SLTM) measurement technique. The new improved SLTM employs a modulated laser beam from a 1.55 {micro}m IR diode laser. The laser is used to create a micro-scale thermal wave in the film by focusing the light through the substrate. At this laser wavelength, the technique can be used to determine the thermal diffusivity for films deposited on semiconductor substrates with the band-gap larger than 0.8eV. The generated thermal wave is detected by a fast responding thermocouple formed between the film surface and the tip of a sharp probe. By scanning the laser beam around the thermocouple, the amplitude and phase distributions of the thermal wave are obtained. The film thermal diffusivity is obtained by fitting the detected phase profile of the thermal wave with a three-dimensional heat conduction model. Experimental results are presented for a film-on-substrate system composed of a two-layer thin film on the silicon substrate. The two-layer film is a 4.65{micro}m silicon dioxide film on which a 100nm thick gold film is deposited in order to provide an absorption layer for the laser light and also to facilitate the thermoelectric detection of the thermal wave.

  18. Laser cooling of electron – ion plasma in the case of optimal scanning of the laser frequency

    SciTech Connect

    Gavrilyuk, A P; Isaev, I L

    2015-11-30

    Laser cooling of ions of electron – ion plasma is studied under the action of spontaneous radiation pressure forces. It is shown that the use of a constant detuning of the laser frequency from the quantum transition frequency w0 in ions significantly limits the conditions under which the ions are cooled. To extend the range of initial temperatures of possible cooling of ions and to increase the cooling efficiency we suggest scanning the laser frequency detuning so that the cooling rate remained maximal in the process of changing the temperature of ions. In the case of an optimal detuning, we have found an asymptotic expression for the cooling rate and identified intervals of electron concentrations and temperatures, where cooling of ions is possible. (interaction of laser radiation with matter. laser plasma)

  19. Determining the nonlinear refractive index of fused quartz by femtosecond laser Z-scan technology

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Ren, Huan; Ma, Hua; Shi, Zhendong; Yang, Yi; Yuan, Quan; Feng, Xiaoxuan; Ma, Yurong; Chen, Bo

    2016-10-01

    Z-scan technology is an experimental technique for determining the nonlinear refractive index based on the principle of transformation of phase distortion to amplitude distortion when a laser beam propagates through a nonlinear material. For most of the Z-scan system based on the nanosecond or picosecond laser, the accumulation of thermal effects becomes a big problem in nonlinear refractive index measurement especially for the nonlinear materials such as fused quartz and neodymium glass which have a weak nonlinear refractive effect. To overcome this problem, a system for determining the nonlinear refractive index of optical materials based on the femtosecond laser Z-scan technology is presented. Using this system, the nonlinear refractive index of the fused quartz is investigated.

  20. Embedding complementary imaging data in laser scanning microscopy micrographs by reversible watermarking.

    PubMed

    Dragoi, Ioan-Catalin; Stanciu, Stefan G; Hristu, Radu; Coanda, Henri-George; Tranca, Denis E; Popescu, Marius; Coltuc, Dinu

    2016-04-01

    Complementary laser scanning microscopy micrographs are considered as pairs consisting in a master image (MI) and a slave image (SI), the latter with potential for facilitating the interpretation of the MI. We propose a strategy based on reversible watermarking for embedding a lossy compressed version of the SI into the MI. The use of reversible watermarking ensures the exact recovery of the host image. By storing and/or transmitting the watermarked MI in a single file, the information contained in both images that constitute the pair is made available to a potential end-user, which simplifies data association and transfer. Examples are presented using support images collected by two complementary techniques, confocal scanning laser microscopy and transmission laser scanning microscopy, on Hematoxylin and Eosin stained tissue fragments. A strategy for minimizing the watermarking distortions of the MI, while preserving the content of the SI, is discussed in detail.

  1. Embedding complementary imaging data in laser scanning microscopy micrographs by reversible watermarking

    PubMed Central

    Dragoi, Ioan-Catalin; Stanciu, Stefan G.; Hristu, Radu; Coanda, Henri-George; Tranca, Denis E.; Popescu, Marius; Coltuc, Dinu

    2016-01-01

    Complementary laser scanning microscopy micrographs are considered as pairs consisting in a master image (MI) and a slave image (SI), the latter with potential for facilitating the interpretation of the MI. We propose a strategy based on reversible watermarking for embedding a lossy compressed version of the SI into the MI. The use of reversible watermarking ensures the exact recovery of the host image. By storing and/or transmitting the watermarked MI in a single file, the information contained in both images that constitute the pair is made available to a potential end-user, which simplifies data association and transfer. Examples are presented using support images collected by two complementary techniques, confocal scanning laser microscopy and transmission laser scanning microscopy, on Hematoxylin and Eosin stained tissue fragments. A strategy for minimizing the watermarking distortions of the MI, while preserving the content of the SI, is discussed in detail. PMID:27446641

  2. Holographic Airborne Rotating Lidar Instrument Experiment (HARLIE)

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.

    1998-01-01

    Scanning holographic lidar receivers are currently in use in two operational lidar systems, PHASERS (Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing) and now HARLIE (Holographic Airborne Rotating Lidar Instrument Experiment). These systems are based on volume phase holograms made in dichromated gelatin (DCG) sandwiched between 2 layers of high quality float glass. They have demonstrated the practical application of this technology to compact scanning lidar systems at 532 and 1064 nm wavelengths, the ability to withstand moderately high laser power and energy loading, sufficient optical quality for most direct detection systems, overall efficiencies rivaling conventional receivers, and the stability to last several years under typical lidar system environments. Their size and weight are approximately half of similar performing scanning systems using reflective optics. The cost of holographic systems will eventually be lower than the reflective optical systems depending on their degree of commercialization. There are a number of applications that require or can greatly benefit from a scanning capability. Several of these are airborne systems, which either use focal plane scanning, as in the Laser Vegetation Imaging System or use primary aperture scanning, as in the Airborne Oceanographic Lidar or the Large Aperture Scanning Airborne Lidar. The latter class requires a large clear aperture opening or window in the aircraft. This type of system can greatly benefit from the use of scanning transmission holograms of the HARLIE type because the clear aperture required is only about 25% larger than the collecting aperture as opposed to 200-300% larger for scan angles of 45 degrees off nadir.

  3. Quasi-4D laser diagnostics using an acousto-optic deflector scanning system

    NASA Astrophysics Data System (ADS)

    Li, Tao; Pareja, Jhon; Becker, Lukas; Heddrich, Wolfgang; Dreizler, Andreas; Böhm, Benjamin

    2017-03-01

    In this paper, a novel scanning system for laser diagnostics was developed and characterized. The system is based on the acousto-optic deflection of a high-speed pulsed laser. Results showed that quasi-volumetric laser illumination with high precision and accuracy can be achieved with a simplified and flexible optical setup. The feasibility of the method for performing high-speed quasi-4D laser diagnostics was demonstrated by the tomographic visualization of a lifted turbulent jet flame using Mie-scattering and multi-plane particle image velocimetry measurements of a turbulent non-reactive mixing case. Three-dimensional flame and flow structures can be detected and tracked with this new scanning system.

  4. Active thermography inspection of protective glass contamination on laser scanning heads.

    PubMed

    Skala, J; Svantner, M; Tesar, J; Franc, A

    2016-12-01

    Industrial lasers are an expanding technology of welding and other materials processing. Lasers with optical scanning heads are often used, as these provide more versatility, accuracy, and speed. The output part of the scanning head is covered by a protective glass, which might get contaminated by various particles from the laser processing. This decreases the transmissivity of the glass, and it can affect the production quality. The contamination needs to be checked regularly, but a visual inspection might not always be effective. This paper proposes two alternative methods of inspecting the protective glass: flash-pulse active thermography, and laser active thermography. They are based on the thermal excitation of the glass and measuring the response with an infrared camera. The experimental setup and practical results are described and the advantages and disadvantages are discussed. The presented methods are proven to be effective in detecting the contamination of the glass.

  5. Multibeam scanning optics with single laser source for full-color printers.

    PubMed

    Maruo, S; Arimoto, A; Kobayashi, S

    1997-10-01

    In the novel optical system described here, four-color toners can be developed in one rotation of the photoconductor, and the color control information is given when the intensities of the laser power levels are changed and the two polarization directions are switched. A polarizing beam splitter between the common scanning optics and the photoconductor enables the laser beam to pass through a common scanning system and to illuminate two positions on the photoconductive material. The laser beam polarization direction is controlled by an electro-optical device immediately behind the laser. In each illuminated position, two-color toners are developed by a three-level (trilevel) photographic process. This simplified optical system eliminates the registration errors that occur with four-color information items and can be useful in high-speed printing systems.

  6. Centimeter-scale MEMS scanning mirrors for high power laser application

    NASA Astrophysics Data System (ADS)

    Senger, F.; Hofmann, U.; v. Wantoch, T.; Mallas, C.; Janes, J.; Benecke, W.; Herwig, Patrick; Gawlitza, P.; Ortega-Delgado, M.; Grune, C.; Hannweber, J.; Wetzig, A.

    2015-02-01

    A higher achievable scan speed and the capability to integrate two scan axes in a very compact device are fundamental advantages of MEMS scanning mirrors over conventional galvanometric scanners. There is a growing demand for biaxial high speed scanning systems complementing the rapid progress of high power lasers for enabling the development of new high throughput manufacturing processes. This paper presents concept, design, fabrication and test of biaxial large aperture MEMS scanning mirrors (LAMM) with aperture sizes up to 20 mm for use in high-power laser applications. To keep static and dynamic deformation of the mirror acceptably low all MEMS mirrors exhibit full substrate thickness of 725 μm. The LAMM-scanners are being vacuum packaged on wafer-level based on a stack of 4 wafers. Scanners with aperture sizes up to 12 mm are designed as a 4-DOF-oscillator with amplitude magnification applying electrostatic actuation for driving a motor-frame. As an example a 7-mm-scanner is presented that achieves an optical scan angle of 32 degrees at 3.2 kHz. LAMM-scanners with apertures sizes of 20 mm are designed as passive high-Q-resonators to be externally excited by low-cost electromagnetic or piezoelectric drives. Multi-layer dielectric coatings with a reflectivity higher than 99.9 % have enabled to apply cw-laser power loads of more than 600 W without damaging the MEMS mirror. Finally, a new excitation concept for resonant scanners is presented providing advantageous shaping of intensity profiles of projected laser patterns without modulating the laser. This is of interest in lighting applications such as automotive laser headlights.

  7. Graph Structure-Based Simultaneous Localization and Mapping Using a Hybrid Method of 2D Laser Scan and Monocular Camera Image in Environments with Laser Scan Ambiguity.

    PubMed

    Oh, Taekjun; Lee, Donghwa; Kim, Hyungjin; Myung, Hyun

    2015-07-03

    Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping) algorithms exploiting a laser scanner may not estimate the robot pose robustly. To resolve this problem, we propose a novel localization approach based on a hybrid method incorporating a 2D laser scanner and a monocular camera in the framework of a graph structure-based SLAM. 3D coordinates of image feature points are acquired through the hybrid method, with the assumption that the wall is normal to the ground and vertically flat. However, this assumption can be relieved, because the subsequent feature matching process rejects the outliers on an inclined or non-flat wall. Through graph optimization with constraints generated by the hybrid method, the final robot pose is estimated. To verify the effectiveness of the proposed method, real experiments were conducted in an indoor environment with a long corridor. The experimental results were compared with those of the conventional GMappingapproach. The results demonstrate that it is possible to localize the robot in environments with laser scan ambiguity in real time, and the performance of the proposed method is superior to that of the conventional approach.

  8. Graph Structure-Based Simultaneous Localization and Mapping Using a Hybrid Method of 2D Laser Scan and Monocular Camera Image in Environments with Laser Scan Ambiguity

    PubMed Central

    Oh, Taekjun; Lee, Donghwa; Kim, Hyungjin; Myung, Hyun

    2015-01-01

    Localization is an essential issue for robot navigation, allowing the robot to perform tasks autonomously. However, in environments with laser scan ambiguity, such as long corridors, the conventional SLAM (simultaneous localization and mapping) algorithms exploiting a laser scanner may not estimate the robot pose robustly. To resolve this problem, we propose a novel localization approach based on a hybrid method incorporating a 2D laser scanner and a monocular camera in the framework of a graph structure-based SLAM. 3D coordinates of image feature points are acquired through the hybrid method, with the assumption that the wall is normal to the ground and vertically flat. However, this assumption can be relieved, because the subsequent feature matching process rejects the outliers on an inclined or non-flat wall. Through graph optimization with constraints generated by the hybrid method, the final robot pose is estimated. To verify the effectiveness of the proposed method, real experiments were conducted in an indoor environment with a long corridor. The experimental results were compared with those of the conventional GMappingapproach. The results demonstrate that it is possible to localize the robot in environments with laser scan ambiguity in real time, and the performance of the proposed method is superior to that of the conventional approach. PMID:26151203

  9. Recent rock fall activity in the Wetterstein Mountains revealed by a time series of terrestrial laser scans

    NASA Astrophysics Data System (ADS)

    Schöpa, Anne; Baewert, Henning; Cook, Kristen; Morche, David

    2015-04-01

    The north face of the Hochwanner in the Reintal valley, Wetterstein Mountains, southern Germany, has been a site of frequent rock fall activity for the past several hundred years. The so-called 'Steingerümpel' rock fall included an estimated volume of 2.3-2.7 x 106 m3 and led to damming of the Partnach river. This event was dated to 1400-1600 AD. The rock fall left a prominent scar in the rock face where subsequent rock fall activity was concentrated, postulated to be a 'delayed consequence' of the Steingerümpel event. Previous workers used airborne and terrestrial laser scan data to evaluate the volume of the detached material and the deposits on the talus cone at the foot of the slope from the 'delayed consequence' activity between 2006 and 2008 (Heckmann et al., 2012). The largest event during this period was a 5 x 104 m3 rock fall in August 2007. We compared the data of six terrestrial laser scans, which were acquired in June and September 2008, September 2010, June 2011, August 2013, October and November 2014, in order to assess the volumes of detached material after the large rock fall event of 2007. The aim is to investigate the post-event activity at a site of a large rock fall in order to give estimates about the timing when the activity is back to normal conditions in relation to the magnitude of the large event. Although no large rock fall occurred in the observation period, the comparison of the laser scan data indicate that the average rock wall retreat at this site is still higher compared to the mean annual rock wall retreat rate of 0.54 mm/yr for the last millennium in the Reintal valley (Krautblatter et al., 2012). This shows that sites of large rock falls remain active even years after the event. Heckmann, T.; Bimböse, M.; Krautblatter, M.; Haas, F.; Becht, M.; Morche, D. (2012): From geotechnical analysis to quantification and modelling using LiDAR data: a study on rockfall in the Reintal catchment, Bavarian Alps, Germany; Earth Surface

  10. Scanning laser differential-heterodyne interferometer for flying-height measurement.

    PubMed

    Ngoi, B K; Venkatakrishnan, K; Tan, B

    2000-02-01

    With conventional optical interferometry flying-height testing, a stationary measurement beam and a two-axis moving stage are used to measure slider-disk spacing at different points on the slider. Pitch angle or roll angle is calculated on the basis of the measurement results. We report on a scanning differential-heterodyne interferometer, which measures the continuous flying-height variation along the edge of a slider with two continuously scanning laser beams. Pitch angle or roll angle can be obtained directly from the scanning measurement. The system can also measure points individually to obtain the absolute flying height at different locations on the slider. Experiments were performed to demonstrate the concept of scanning measurement. The flying-height variation along the slider edge was measured by continuous scan and by point-to-point moving. The measurement results from continuous scan coincided with those of conventional methods.

  11. Multicolor immunophenotyping of tissue sections by laser scanning cytometry (LSC)

    NASA Astrophysics Data System (ADS)

    Tarnok, Attila; Gerstner, Andreas O.; Lenz, Dominik; Osmancik, Pavel; Schneider, Peter; Trumpfheller, Christine; Racz, Pal; Tenner-Racz, Klara

    2002-05-01

    In lymphatic organs the quantitative analysis of the spatial distribution of leukocytes would give relevant information about alterations during diseases (leukemia, HIV, AIDS) and their therapeutic regimen. Analysis of them in solid tissues is difficult to perform but would yield important data in a variety of clinical and experimental settings. We have developed an automated analysis method for LSC suitable for archived or fresh biopsy material of human lymph nodes and tonsils. Sections are stained with PI for DNA and up to three antigens using direct or indirect immunofluorescence staining. Measurement is triggered on DNA-fluorescence (Argon Laser). Due to the heterogeneity in cell density measurements are repeatedly performed at different threshold levels (low threshold: regions of low cellular density, germinal centers; high threshold: dense regions, mantle zone). Data are acquired by single- (Ar) or dual-laser excitation (Ar-HeNe) in order to determine data from single- (FITC), up to triple-staining (FITC/PE-Cy5/APC). Percentage and cellular density of cell-subsets is quantified in different structural regions of the specimen. Comparison with manual analysis of identical specimens showed very good correlation. With LSC a semi-automated operator-independent and immunophenotyping of lymphatic tissues with simultaneously up to four antibodies is possible. This technique should yield new insight into processes during diseases and should help to quantify the success of therapeutic interventions.

  12. Laser power and Scanning Speed Influence on the Mechanical Property of Laser Metal Deposited Titanium-Alloy

    NASA Astrophysics Data System (ADS)

    Ma