Publications of year 2001

Publications of year 2001

Books and proceedings

Y. Bar-Shalom, X. R. Li, and T. Kirubarajan. Estimation with Applications to Tracking and Navigation. Wiley, 2001.

@book{RefWorks:766,
author={Y. Bar-Shalom and X. R. Li and T. Kirubarajan},
year={2001},
title={Estimation with Applications to Tracking and Navigation},
publisher={Wiley} 
}

R. O. Duda, P. E. Hart, and D. G. Stork. Pattern Classification. Wiley, 2001.

@book{RefWorks:771,
author={R. O. Duda and P. E. Hart and D. G. Stork},
year={2001},
title={Pattern Classification},
publisher={Wiley} 
}

J. G. Proakis and M. Salehi. Communication Systems Engineering. Prentice Hall, New York, 2001.

@book{RefWorks:779,
author={J. G. Proakis and M. Salehi},
year={2001},
title={Communication Systems Engineering},
publisher={Prentice Hall},
address={New York} 
}

K. Clint Slatton. Adaptive Multiscale Estimation for Fusing Image Data. Ph.D. Dissertation, University of Texas at Austin, 2001. Note: NOTE: My dissertation.

@book{RefWorks:706,
author={K. Clint Slatton},
year={2001},
title={Adaptive Multiscale Estimation for Fusing Image Data},
publisher={Ph.D. Dissertation, University of Texas at Austin},
note={NOTE: My dissertation.} 
}

Articles in journal or book chapters

J. Bryan Blair, Michelle A. Hofton, and Scott B. Luthcke. WIDE-SWATH IMAGING LIDAR DEVELOPMENT FOR AIRBORNE AND SPACEBORNE APPLICATIONS. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:17-20, 2001. [WWW ] Keyword(s): laser altimetry, lidar, altimetry, mapping. Abstract:

With laser altimetry becoming increasingly accepted by the global Earth science community as a source for accurate topographic data, there is now a desire to apply this technology to large area mapping. Commonly, airborne laser systems provide data at several meter resolution and across swaths up to 1-2 km in width. Economic factors drive commercial systems to widen swaths further, but off-nadir incident angles degrade accuracy and significantly diminish the ability to penetrate dense vegetation canopies effectively limiting swath width. Higher operational altitudes (e.g., 10 km vs. 1 km) can provide up to a factor of ten increase in swath width within a selected angular range. However, higher altitude operations require significantly more laser output power, smaller divergence angles and higher beam quality to achieve smaller footprints. At NASA Goddard Space Flight Center, we have been prototyping spaceborne instrumentation and science applications of wide-swath lidar in aircraft for the last several years. This experience has led to the development of several satellite laser altimeters such as the Shuttle Laser Altimeter (SLA) and Vegetation Canopy Lidar (VCL). Technologies and methods utilized in the spaceborne environment are prototyped in the wide-swath, full-waveform airborne Laser Vegetation Imaging Sensor (LVIS). This sensor will undertake a large-area mapping mission in Brazil in June-August 2002. The sensor will use a 3 km-wide data swath and plans are underway to increase the swath width further. Spaceborne imaging applications require significantly higher effective rep-rates than airborne systems and are much less tolerant of unreliable mechanical scanning and equipment maintenance requirements. Unique scanning and ranging techniques for medium-large footprint, full-waveform mapping laser altimeters are currently under development to enable a spaceborne, wide-swath operational mapping laser altimeter capable of full-Earth mapping and dense vegetation penetration. A sample of some of the techniques being developed at NASA Goddard Space Flight Center for future airborne and spaceborne imaging lidar will be presented, including methods for achieving MHz scanning rates.

@Article{blair01,
author = {J. Bryan Blair and Michelle A. Hofton and Scott B. Luthcke},
title = {WIDE-SWATH IMAGING LIDAR DEVELOPMENT FOR AIRBORNE AND SPACEBORNE APPLICATIONS},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {17-20},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {laser altimetry, lidar, altimetry, mapping},
abstract = {With laser altimetry becoming increasingly accepted by the global Earth science community as a source for accurate topographic data, there is now a desire to apply this technology to large area mapping. Commonly, airborne laser systems provide data at several meter resolution and across swaths up to 1-2 km in width. Economic factors drive commercial systems to widen swaths further, but off-nadir incident angles degrade accuracy and significantly diminish the ability to penetrate dense vegetation canopies effectively limiting swath width. Higher operational altitudes (e.g., 10 km vs. 1 km) can provide up to a factor of ten increase in swath width within a selected angular range. However, higher altitude operations require significantly more laser output power, smaller divergence angles and higher beam quality to achieve smaller footprints. At NASA Goddard Space Flight Center, we have been prototyping spaceborne instrumentation and science applications of wide-swath lidar in aircraft for the last several years. This experience has led to the development of several satellite laser altimeters such as the Shuttle Laser Altimeter (SLA) and Vegetation Canopy Lidar (VCL). Technologies and methods utilized in the spaceborne environment are prototyped in the wide-swath, full-waveform airborne Laser Vegetation Imaging Sensor (LVIS). This sensor will undertake a large-area mapping mission in Brazil in June-August 2002. The sensor will use a 3 km-wide data swath and plans are underway to increase the swath width further. Spaceborne imaging applications require significantly higher effective rep-rates than airborne systems and are much less tolerant of unreliable mechanical scanning and equipment maintenance requirements. Unique scanning and ranging techniques for medium-large footprint, full-waveform mapping laser altimeters are currently under development to enable a spaceborne, wide-swath operational mapping laser altimeter capable of full-Earth mapping and dense vegetation penetration. A sample of some of the techniques being developed at NASA Goddard Space Flight Center for future airborne and spaceborne imaging lidar will be presented, including methods for achieving MHz scanning rates.},

}

Claudia C. Carabajal and David J. Harding. EVALUATION OF GEOSCIENCE LASER ALTIMETER SYSTEM (GLAS) WAVEFORMS FOR VEGETATED LANDSCAPES USING AIRBORNE LASER ALTIMETER SCANNING DATA. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:125-128, 2001. [WWW ] Keyword(s): LIDAR, laser altimetry, laser waveform analysis, waveform simulations, topography, vegetation. Abstract:

The Geoscience Laser Altimeter System aboard NASA s Ice, Cloud and land Elevation Satellite will record the height distribution of laser energy reflected from surfaces within 70 m diameter footprints. For land surfaces, post-processing of this waveform data will be used to estimate the within-footprint mean elevation and surface relief due to ground slope and roughness, vegetation cover, buildings and other structures. A methodology is described for validating the derived surface properties for vegetated and urbanized landscapes using a GLAS waveform simulator applied to high-resolution, airborne, scanning laser altimeter data being acquired by the Puget Sound Lidar Consortium (PSLC) in northwestern Washington state. The GLAS waveform simulator is being modified to operate on 3- dimensional representations of topography and vegetation cover with the incorporation of digital elevation models derived from the airborne laser data and representations of the spatial distribution of surface reflectance, the transmitted laser energy measured on a perpulse basis by the GLAS instrument, and detector's field-of-view responsivity. The attributes of the PSLC airborne laser mapping data are also described.

@Article{carabajal01,
author = {Claudia C. Carabajal and David J. Harding},
title = {EVALUATION OF GEOSCIENCE LASER ALTIMETER SYSTEM (GLAS) WAVEFORMS FOR VEGETATED LANDSCAPES USING AIRBORNE LASER ALTIMETER SCANNING DATA},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {125-128},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {LIDAR, laser altimetry, laser waveform analysis, waveform simulations, topography, vegetation},
abstract = {The Geoscience Laser Altimeter System aboard NASA s Ice, Cloud and land Elevation Satellite will record the height distribution of laser energy reflected from surfaces within 70 m diameter footprints. For land surfaces, post-processing of this waveform data will be used to estimate the within-footprint mean elevation and surface relief due to ground slope and roughness, vegetation cover, buildings and other structures. A methodology is described for validating the derived surface properties for vegetated and urbanized landscapes using a GLAS waveform simulator applied to high-resolution, airborne, scanning laser altimeter data being acquired by the Puget Sound Lidar Consortium (PSLC) in northwestern Washington state. The GLAS waveform simulator is being modified to operate on 3- dimensional representations of topography and vegetation cover with the incorporation of digital elevation models derived from the airborne laser data and representations of the spatial distribution of surface reflectance, the transmitted laser energy measured on a perpulse basis by the GLAS instrument, and detector's field-of-view responsivity. The attributes of the PSLC airborne laser mapping data are also described.},



}

W. E. Carter, R. Shrestha, G. Tuell, D. Bloomquist, and M. Sartori. Airborne Laser Swath Mapping Shines New Light on Earth's Topography. EOS, Transactions, American Geophysical Union, 82(46):549,550,555, 2001.

@article{RefWorks:795,
author={W. E. Carter and R. Shrestha and G. Tuell and D. Bloomquist and M. Sartori},
year={2001},
title={Airborne Laser Swath Mapping Shines New Light on Earth's Topography},
journal={EOS, Transactions, American Geophysical Union},
volume={82},
number={46},
pages={549,550,555} 
}

T. Castel, A. Beaudoin, N. Floury, T. Le Toan, Y. Caraglio, and J.F. Barczi. Deriving forest canopy parameters for backscatter models using the AMAP architectural plant model. tgars, 39(3):571-583, 2001. [WWW ] Keyword(s): vegetation mapping, backscatter, remote sensing by radar, forest, canopy parameters, backscatter models, AMAP architectural plant model, theoretical scattering models, remote sensing data, natural media, botanical growth processes, plant measurements, flexible interface software, AMAP2SAR, trees, 3D plants, cylinders, radiative transfer models, Austrian black pine plantations, southern France, forest parameters, EM models, vertical heterogeneity, forest stands, crown layer variability, age, canopy depth, C-band, L-band. Abstract:

A new approach using an architectural plant model to feed various theoretical scattering models is presented as a better interpretation of future remote sensing data acquired over natural media. The method is based on the architectural plant model (AMAP), which integrates knowledge of botanical growth processes and real plant measurements. AMAP is encapsulated in a flexible interface software called AMAP2SAR that allows one to (1) simulate a three-dimensional (3-D) plant such as a tree, (2) transform the tree into a collection of cylinders, and (3) feed theoretical models such as radiative transfer (RT) models. The method is illustrated by an example of Austrian black pine plantations in southern France. Simulated characteristics of black pines are validated for stands up to 50 years old and for a given environment. The results show the ability to derive classical forest parameters as well as those needed for electromagnetic models (such as geometry) as a function of age. Vertical profiles of canopy elements are derived and point out the vertical heterogeneity of the stands after they are 20 years old for parameters having an impact on the backscatter such as diameter and number of branches. Consequently, the crown layer variability with age and canopy depth should be considered in RT models. An RT model is modified in order to take account of accurate canopy descriptions and deal with encouraging modeling results at Cand L-band over the same test site.

@Article{castel01,
author = {T. Castel and A. Beaudoin and N. Floury and T. Le Toan and Y. Caraglio and J.F. Barczi},
title = {Deriving forest canopy parameters for backscatter models using the AMAP architectural plant model },
journal = {tgars},
year = {2001},
volume = {39},
pages = {571-583},
number = {3},
url = {http://ieeexplore.ieee.org/iel5/36/19663/00911115.pdf?isNumber=19663&prod=JNL&arnumber=00911115},
keyword = {vegetation mapping,backscatter,remote sensing by radar,forest,canopy parameters,backscatter models ,AMAP architectural plant model , theoretical scattering models ,remote sensing data,natural media , botanical growth processes ,plant measurements,flexible interface software,AMAP2SAR,trees ,3D plants,cylinders,radiative transfer models ,Austrian black pine plantations,southern France , forest parameters ,EM models,vertical heterogeneity,forest stands ,crown layer variability,age,canopy depth,C-band,L-band},
abstract = {A new approach using an architectural plant model to feed various theoretical scattering models is presented as a better interpretation of future remote sensing data acquired over natural media. The method is based on the architectural plant model (AMAP), which integrates knowledge of botanical growth processes and real plant measurements. AMAP is encapsulated in a flexible interface software called AMAP2SAR that allows one to (1) simulate a three-dimensional (3-D) plant such as a tree, (2) transform the tree into a collection of cylinders, and (3) feed theoretical models such as radiative transfer (RT) models. The method is illustrated by an example of Austrian black pine plantations in southern France. Simulated characteristics of black pines are validated for stands up to 50 years old and for a given environment. The results show the ability to derive classical forest parameters as well as those needed for electromagnetic models (such as geometry) as a function of age. Vertical profiles of canopy elements are derived and point out the vertical heterogeneity of the stands after they are 20 years old for parameters having an impact on the backscatter such as diameter and number of branches. Consequently, the crown layer variability with age and canopy depth should be considered in RT models. An RT model is modified in order to take account of accurate canopy descriptions and deal with encouraging modeling results at Cand L-band over the same test site. },



}

Thierry Castel, Yves Caraglio, André Beaudoin, and Frédéric Borne. Using SIR-C SAR Data and the AMAP Model for Forest Attributes Retrieval and 3-D Stand Simulation. rse, 75(2):279-290, 2001. [WWW ] Abstract:

Space-borne Synthetic Aperture Radar (SAR) data and the plant architectural model AMAP are new tools, currently under development and validation, for the retrieval and mapping of forest parameters through a Geographical Information System (GIS). On one hand, L-band SAR data are useful for the retrieval of some forest attributes such as age and woody volume. On the other hand, validated growth model of tree architecture allows retrieval of many forest parameters at tree level and simulation of virtual 3-D views both at the tree and stand levels. To this aim, a methodology is proposed using L-HV SIR-C SAR data or AMAP alone or their coupling through a GIS for forest attributes retrieval and 3-D stand simulation. This approach is illustrated on a simple forest ecosystem, an Austrian pine forest over hilly terrain in southern of France. Results show the potentialities and interests in using such tools when retrieval bole volume is limited to 300 m3/ha; AMAP allowed estimation according to tree (compartment) partitioning as a function of growth stage. The coupling approach gives realistic 3-D stand visualization when it is exercised with GIS data sets and error sources are pointed out toward future improvement and generalization.

@Article{castel01a,
author = {Thierry Castel and Yves Caraglio and André Beaudoin and Frédéric Borne},
title = {Using SIR-C SAR Data and the AMAP Model for Forest Attributes Retrieval and 3-D Stand Simulation},
journal = rse,
year = {2001},
volume = {75},
pages = {279-290},
number = {2},
url = {http://www.sciencedirect.com/science/article/B6V6V-4292M17-T/1/214cbccd4e5334658173c2c2e7b8fd83},
keyword = {},
abstract = {Space-borne Synthetic Aperture Radar (SAR) data and the plant architectural model AMAP are new tools, currently under development and validation, for the retrieval and mapping of forest parameters through a Geographical Information System (GIS). On one hand, L-band SAR data are useful for the retrieval of some forest attributes such as age and woody volume. On the other hand, validated growth model of tree architecture allows retrieval of many forest parameters at tree level and simulation of virtual 3-D views both at the tree and stand levels. To this aim, a methodology is proposed using L-HV SIR-C SAR data or AMAP alone or their coupling through a GIS for forest attributes retrieval and 3-D stand simulation. This approach is illustrated on a simple forest ecosystem, an Austrian pine forest over hilly terrain in southern of France. Results show the potentialities and interests in using such tools when retrieval bole volume is limited to 300 m3/ha; AMAP allowed estimation according to tree (compartment) partitioning as a function of growth stage. The coupling approach gives realistic 3-D stand visualization when it is exercised with GIS data sets and error sources are pointed out toward future improvement and generalization. },



}

John Degnan, Jan McGarry, Thomas Zagwodzki, Phillip Dabney, and Jennifer Geiger. DESIGN AND PERFORMANCE OF AN AIRBORNE MULTIKILOHERTZ PHOTON-COUNTING, MICROLASER ALTIMETER. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:9-16, 2001. [WWW ] Keyword(s): laser ranging, laser altimetry, photon-counting, microchip lasers, subnanosecond pulse, segmented anode photomultipliers, detector arrays, optical scanners. Abstract:

The present paper reports on the design and performance of a scanning, photon-counting laser altimeter, capable of daylight operations from aircraft cruise altitudes. In test flights, the system has successfully recorded high repetition rate, single photon returns from clouds, soils, man-made objects, vegetation, and water surfaces under full solar illumination. Following the flights, the signal was reliably extracted from the solar noise background using a Post-Detection Poisson Filtering technique. The passively Q-switched microchip Nd:YAG laser measures only 2.25 mm in length and is pumped by a single 1.2 Watt GaAs laser diode. The output is frequency-doubled to take advantage of higher detector counting efficiencies and narrower spectral filters available at 532 nm. The transmitter produces a few microjoules of green energy in a subnanosecond pulse at few kilohertz rates. The illuminated ground area is imaged by a 14 cm diameter, diffraction-limited, off-axis telescope onto a segmented anode photomultiplier. Each anode segment is input to one channel of "fine" range receiver (5 cm resolution), which records the times-of-flight of individual photons. A parallel "coarse" receiver provides a lower resolution (>75 cm) histogram of all scatterers between the aircraft and ground and centers the "fine" receiver gate on the last set of returns.

@Article{degnan01,
author = {John Degnan and Jan McGarry and Thomas Zagwodzki and Phillip Dabney and Jennifer Geiger},
title = {DESIGN AND PERFORMANCE OF AN AIRBORNE MULTIKILOHERTZ PHOTON-COUNTING, MICROLASER ALTIMETER},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {9-16},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {laser ranging, laser altimetry, photon-counting, microchip lasers, subnanosecond pulse, segmented anode photomultipliers, detector arrays, optical scanners},
abstract = {The present paper reports on the design and performance of a scanning, photon-counting laser altimeter, capable of daylight operations from aircraft cruise altitudes. In test flights, the system has successfully recorded high repetition rate, single photon returns from clouds, soils, man-made objects, vegetation, and water surfaces under full solar illumination. Following the flights, the signal was reliably extracted from the solar noise background using a Post-Detection Poisson Filtering technique. The passively Q-switched microchip Nd:YAG laser measures only 2.25 mm in length and is pumped by a single 1.2 Watt GaAs laser diode. The output is frequency-doubled to take advantage of higher detector counting efficiencies and narrower spectral filters available at 532 nm. The transmitter produces a few microjoules of green energy in a subnanosecond pulse at few kilohertz rates. The illuminated ground area is imaged by a 14 cm diameter, diffraction-limited, off-axis telescope onto a segmented anode photomultiplier. Each anode segment is input to one channel of "fine" range receiver (5 cm resolution), which records the times-of-flight of individual photons. A parallel "coarse" receiver provides a lower resolution (>75 cm) histogram of all scatterers between the aircraft and ground and centers the "fine" receiver gate on the last set of returns.},



}

Jason B. Drake, Ralph Dubayah, Robert G. Knox, David B. Clark, and Richard Condit. RELATIONSHIP BETWEEN LIDAR METRICS AND ABOVEGROUND BIOMASS IN CLOSED-CANOPY NEOTROPICAL FORESTS. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:147-154, 2001. [WWW ] Keyword(s): lidar, aboveground biomass, carbon stocks, tropical forest structure. Abstract:

Previous studies have shown that canopy metrics from lidar data are highly correlated with aboveground biomass in a variety of closedcanopy forests, however the generality of these site-specific relationships has remained untested. In this study, we compare relationships between lidar canopy metrics and forest structural summaries from a tropical wet forest site in Costa Rica and across a series of tropical moist forest field sites in Panama. We found that in both regions lidar metrics were strongly correlated with forest structural summaries including mean stem diameter, basal area and aboveground biomass. We also showed that the relationships differed between these regions unless deciduousness of canopy trees in Panama was considered. Adjusting for leaf-drop removed statistically significant differences between the two regions in the relationships between a lidar metric and both mean stem diameter and basal area. The relationships between lidar metrics and aboveground biomass, however, remained significantly different between the two study areas because of different general allometric relationships used to estimate aboveground biomass in tropical wet forests and tropical moist forests. Future efforts should continue to examine climatic factors that may influence the generality of the relationships between lidar metrics and forest structural characteristics, and address the dearth of allometric data on the very large trees that can dominate the biomass of primary tropical forests.

@Article{drake01,
author = {Jason B. Drake and Ralph Dubayah and Robert G. Knox and David B. Clark and Richard Condit},
title = {RELATIONSHIP BETWEEN LIDAR METRICS AND ABOVEGROUND BIOMASS IN CLOSED-CANOPY NEOTROPICAL FORESTS},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {147-154},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {lidar, aboveground biomass, carbon stocks, tropical forest structure},
abstract = {Previous studies have shown that canopy metrics from lidar data are highly correlated with aboveground biomass in a variety of closedcanopy forests, however the generality of these site-specific relationships has remained untested. In this study, we compare relationships between lidar canopy metrics and forest structural summaries from a tropical wet forest site in Costa Rica and across a series of tropical moist forest field sites in Panama. We found that in both regions lidar metrics were strongly correlated with forest structural summaries including mean stem diameter, basal area and aboveground biomass. We also showed that the relationships differed between these regions unless deciduousness of canopy trees in Panama was considered. Adjusting for leaf-drop removed statistically significant differences between the two regions in the relationships between a lidar metric and both mean stem diameter and basal area. The relationships between lidar metrics and aboveground biomass, however, remained significantly different between the two study areas because of different general allometric relationships used to estimate aboveground biomass in tropical wet forests and tropical moist forests. Future efforts should continue to examine climatic factors that may influence the generality of the relationships between lidar metrics and forest structural characteristics, and address the dearth of allometric data on the very large trees that can dominate the biomass of primary tropical forests.},



}

M. Elmqvist, E. Jungert, F. Lantz, A. Persson, and U .Söderman. TERRAIN MODELLING AND ANALYSIS USING LASER SCANNER DATA. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:219-226, 2001. [WWW ] Keyword(s): airborne laser scanning, digital terrain model, ground surface modelling, single tree detection, laser data classification, terrain database, qualitative methods, resolution pyramid. Abstract:

Very detailed high-resolution (3D) digital terrain models can be obtained using airborne laser scanner data. However, laser scanning usually entails huge data sets even for moderate areas, making data management and analysis both complex and time consuming. For this reason, automatic terrain modelling and efficient storage structures supporting data access are needed. In this paper a number of methods supporting automatic construction of 3D digital terrain models, especially ground surface modelling and detection and measurement of individual trees will be discussed. Furthermore automatic and/or interactive terrain feature analysis will be discussed. A special data representation structure for the terrain model allowing efficient data storage and data access will be presented. Beside this, it is possible to create a symbolic information structure from the terrain model that can be used in queries for determination of different terrain features, such as ditches or ridges etc., but also for detection of changes in the terrain.

@Article{elmqvist01,
author = {M. Elmqvist and E. Jungert and F. Lantz and A. Persson and U .Söderman},
title = {TERRAIN MODELLING AND ANALYSIS USING LASER SCANNER DATA},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {219-226},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {airborne laser scanning, digital terrain model, ground surface modelling, single tree detection, laser data classification, terrain database, qualitative methods, resolution pyramid},
abstract = {Very detailed high-resolution (3D) digital terrain models can be obtained using airborne laser scanner data. However, laser scanning usually entails huge data sets even for moderate areas, making data management and analysis both complex and time consuming. For this reason, automatic terrain modelling and efficient storage structures supporting data access are needed. In this paper a number of methods supporting automatic construction of 3D digital terrain models, especially ground surface modelling and detection and measurement of individual trees will be discussed. Furthermore automatic and/or interactive terrain feature analysis will be discussed. A special data representation structure for the terrain model allowing efficient data storage and data access will be presented. Beside this, it is possible to create a symbolic information structure from the terrain model that can be used in queries for determination of different terrain features, such as ditches or ridges etc., but also for detection of changes in the terrain.},



}

Manabu FUNAHASHI, Masahiro SETOJIMA, Yukio AKAMATSU, and Yasuteru IMAI. Investigation of Measuring Accuracy of Forest Area by Means of Airborne Laser Scanner. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:139-146, 2001. [WWW ] Keyword(s): airborne laser scanner, sinks, global warming, tree height measurement, measuring accuracy. Abstract:

It is an important subject to accurately measure forests that serve as sinks since the global warming is taken up as a serious problem in recent years. Tree height and so on have so far been measured by the conventional direct or indirect measuring method. Presently, however, the measuring accuracy by airborne laser scanner has been improved and it is now reaching the stage of practical use for measuring forests as well. For this study, we selected the forest of Tama Forest Science Garden (Hachioji, Tokyo) of Forestry and Forest Products Research Institute as an investigation field where various types of trees grow and a database is constructed. Then we compared the data obtained with the laser scanner with the results of topographic survey and tree height measurement conducted at the investigation field of a specific range and investigated the accuracy of measuring the forest area. According to the verification result relating to the DEM accuracy, the error of the DEM made from the laser scanner to the actually measured value was about 50cm(min.). As a result of accuracy investigation of tree height, a large difference was found in measuring error depending on the growth condition of trees (tree shape). At a place where trees grow almost vertically, the difference between the DSM and tree height value actually measured was small. However, at places where trees grow obliquely or trees are intertwined in a complicated way, the measuring error was large.

@Article{funahashi01,
author = {Manabu FUNAHASHI and Masahiro SETOJIMA and Yukio AKAMATSU and Yasuteru IMAI},
title = {Investigation of Measuring Accuracy of Forest Area by Means of Airborne Laser Scanner},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {139-146},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {airborne laser scanner, sinks, global warming, tree height measurement, measuring accuracy},
abstract = {It is an important subject to accurately measure forests that serve as sinks since the global warming is taken up as a serious problem in recent years. Tree height and so on have so far been measured by the conventional direct or indirect measuring method. Presently, however, the measuring accuracy by airborne laser scanner has been improved and it is now reaching the stage of practical use for measuring forests as well. For this study, we selected the forest of Tama Forest Science Garden (Hachioji, Tokyo) of Forestry and Forest Products Research Institute as an investigation field where various types of trees grow and a database is constructed. Then we compared the data obtained with the laser scanner with the results of topographic survey and tree height measurement conducted at the investigation field of a specific range and investigated the accuracy of measuring the forest area. According to the verification result relating to the DEM accuracy, the error of the DEM made from the laser scanner to the actually measured value was about 50cm(min.). As a result of accuracy investigation of tree height, a large difference was found in measuring error depending on the growth condition of trees (tree shape). At a place where trees grow almost vertically, the difference between the DSM and tree height value actually measured was small. However, at places where trees grow obliquely or trees are intertwined in a complicated way, the measuring error was large.},



}

Sagi Filin. Recovery of Systematic Biases in Laser Altimeters Using Natural Surfaces. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:85-91, 2001. [WWW ] Keyword(s): Laser Altimetry, Error model, Calibration. Abstract:

Elements of accuracy of LIDAR systems and the corrections of systematic errors have received growing attention in recent years. The expected level of accuracy and the additional processing that is needed for making the raw data ready to use are a®ected directly by the systematic errors in the laser data. It is evident that calibration of the LIDAR system, both laboratory and in-°ight, are mandatory to alleviate these de¯ciencies. This paper presents an error recovery model that is based on modeling the system errors and on de¯ning adequate control information. The association of the observations and control information, and con¯gurations that enhance the reliability of the recovered parameters, are also studied here in detail.

@Article{filin01,
author = {Sagi Filin},
title = {Recovery of Systematic Biases in Laser Altimeters Using Natural Surfaces},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {85-91},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Laser Altimetry, Error model, Calibration},
abstract = {Elements of accuracy of LIDAR systems and the corrections of systematic errors have received growing attention in recent years. The expected level of accuracy and the additional processing that is needed for making the raw data ready to use are a®ected directly by the systematic errors in the laser data. It is evident that calibration of the LIDAR system, both laboratory and in-°ight, are mandatory to alleviate these de¯ciencies. This paper presents an error recovery model that is based on modeling the system errors and on de¯ning adequate control information. The association of the observations and control information, and con¯gurations that enhance the reliability of the recovered parameters, are also studied here in detail.},



}

R. Forsberg, K. Keller, and S. M. Jacobsen. LASER MONITORING OF ICE ELEVATIONS AND SEA-ICE THICKNESS IN GREENLAND. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:163-168, 2001. [WWW ] Keyword(s): Laser altimetry, laser scanning, SAR interferometry, glaciers, sea-ice. Abstract:

A low-cost Twin-Otter based laser altimetry and scanning system have been set up by KMS in several different commercial aircraft, and flown extensively in connection with airborne gravity activities in the Arctic Ocean north of Greenland, as well as on various research projects on the ice sheet and coastal glaciers in Greenland. The hardware system is based on a Riegl laser swath scanner or Optech laser altimeter combined with numerous GPS receivers. Roll and pitch are provided by either a medium-grade commercial INS or a low-cost custom-made IMU with fiber-optics gyros. The whole system is designed for use on non-dedicated aircraft, with a minimum of set-up time. In the paper we outline the hardware setup, processing schemes and give some examples of field campaigns and estimated accuracies. Measurements over sea-ice in the Polar Sea north of Greenland have shown that sea-ice freeboard can readily be measured combining laser altimetry and a local geoid model, yielding an indirect measurement of sea-ice thickness. Over land ice laser results have, a.o., been used to study radar penetration effects of airborne SAR interferometry, showing large height-dependent variations, corresponding to changes in snow facies.

@Article{forsberg01,
author = {R. Forsberg and K. Keller and S. M. Jacobsen},
title = {LASER MONITORING OF ICE ELEVATIONS AND SEA-ICE THICKNESS IN GREENLAND},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {163-168},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Laser altimetry, laser scanning, SAR interferometry, glaciers, sea-ice},
abstract = {A low-cost Twin-Otter based laser altimetry and scanning system have been set up by KMS in several different commercial aircraft, and flown extensively in connection with airborne gravity activities in the Arctic Ocean north of Greenland, as well as on various research projects on the ice sheet and coastal glaciers in Greenland. The hardware system is based on a Riegl laser swath scanner or Optech laser altimeter combined with numerous GPS receivers. Roll and pitch are provided by either a medium-grade commercial INS or a low-cost custom-made IMU with fiber-optics gyros. The whole system is designed for use on non-dedicated aircraft, with a minimum of set-up time. In the paper we outline the hardware setup, processing schemes and give some examples of field campaigns and estimated accuracies. Measurements over sea-ice in the Polar Sea north of Greenland have shown that sea-ice freeboard can readily be measured combining laser altimetry and a local geoid model, yielding an indirect measurement of sea-ice thickness. Over land ice laser results have, a.o., been used to study radar penetration effects of airborne SAR interferometry, showing large height-dependent variations, corresponding to changes in snow facies.},



}

Roberto Fraile and Steve Maybank. Comparing Probabilistic and Geometric Models On Lidar Data. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:67-70, 2001. [WWW ] Abstract:

A bottleneck in the use of Geographic Information Systems (GIS) is the cost of data acquisition. In our case, we are interested in producing GIS layers containing useful information for river ood impact assessment. Geometric models can be used to describe regions of the data which correspond to man-made constructions. Probabilistic models can be used to describe vegetation and other features. Our purpose is to compare geometric and probabilistic models on small regions of interest in lidar data, in order to choose which type of models renders a better description in each region. To do so, we use the Minimum Description Length principle of statistical inference, which states that best descriptions are those which better compress the data. By comparing computer programs that generate the data under different assumptions we can decide which type of models conveys more useful information about each region of interest

@Article{fraile01,
author = {Roberto Fraile and Steve Maybank},
title = {Comparing Probabilistic and Geometric Models On Lidar Data},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {67-70},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {},
abstract = {A bottleneck in the use of Geographic Information Systems (GIS) is the cost of data acquisition. In our case, we are interested in producing GIS layers containing useful information for river ood impact assessment. Geometric models can be used to describe regions of the data which correspond to man-made constructions. Probabilistic models can be used to describe vegetation and other features. Our purpose is to compare geometric and probabilistic models on small regions of interest in lidar data, in order to choose which type of models renders a better description in each region. To do so, we use the Minimum Description Length principle of statistical inference, which states that best descriptions are those which better compress the data. By comparing computer programs that generate the data under different assumptions we can decide which type of models conveys more useful information about each region of interest},



}

D.J. Harding, M.A. Lefsky, G.G. Parker, and J.B. Blair. Laser altimeter canopy height profiles: Methods and validation for closed-canopy, broadleaf forests. rse, 76:283-297, 2001. [WWW ] Keyword(s): Laser, Altimeter, Forest, Canopy, Structure, Height, Broadleaf, Lidar, Altimetry, Waveform, SLICER. Abstract:

Waveform-recording laser altimeter observations of vegetated landscapes provide a time-resolved measure of laser pulse backscatter energy from canopy surfaces and the underlying ground. Airborne laser altimeter waveform data was acquired using the Scanning Lidar Imager of Canopies by Echo Recovery (SLICER) for a successional sequence of four, closed-canopy, deciduous forest stands in eastern Maryland. The four stands were selected so as to include a range of canopy structures of importance to forest ecosystem function, including variation in the height and roughness of the outermost canopy surface and the vertical organization of canopy stories and gaps. The character of the SLICER backscatter signal is described and a method is developed that accounts for occlusion of the laser energy by canopy surfaces, transforming the backscatter signal to a canopy height profile (CHP) that quantitatively represents the relative vertical distribution of canopy surface area. The transformation applies increased weighting to the backscatter amplitude as a function of closure through the canopy and assumes a horizontally random distribution of the canopy components. SLICER CHPs, averaged over areas of overlap where altimeter ground tracks intersect, are shown to be highly reproducible. CHP transects across the four stands reveal spatial variations in vegetation, at the scale of the individual 10-m-diameter laser footprints, within and between stands. Averaged SLICER CHPs are compared to analogous height profile results derived from ground-based sightings to plant intercepts measured on plots within the four stands. The plots were located on the segments of the altimeter ground tracks from which averaged SLICER CHPs were derived, and the ground observations were acquired within 2 weeks of the SLICER data acquisition to minimize temporal change. The differences in canopy structure between the four stands is similarly described by the SLICER and ground-based CHP results. However, a chi-square test of similarity documents differences that are statistically significant. The differences are discussed in terms of measurement properties that define the smoothness of the resulting CHPs and canopy properties that may vertically bias the CHP representations of canopy structure. The statistical differences are most likely due to the more noisy character of the ground-based CHPs, especially high in the canopy where ground-based sightings are rare resulting in an underestimate of canopy surface area and height, and to departures from assumptions of canopy uniformity, particularly regarding lack of clumping and vertically constant canopy reflectance, which bias the CHPs. The results demonstrate that the SLICER observations reliably provide a measure of canopy structure that reveals ecologically interesting structural variations such as those characterizing a successional sequence of closed-canopy, broadleaf forest stands.

@Article{harding00,
author = {D.J. Harding and M.A. Lefsky and G.G. Parker and J.B. Blair},
title = {Laser altimeter canopy height profiles: Methods and validation for closed-canopy, broadleaf forests},
journal = rse,
year = {2001},
volume = {76},
pages = {283-297},
keyword = {Laser, Altimeter, Forest, Canopy, Structure, Height; Broadleaf, Lidar, Altimetry, Waveform, SLICER},
url = {http://www.sciencedirect.com/science/article/B6V6V-43HVM3D-1/1/f635ca3600ab5f23cd96ea07f4d783b8},
abstract = {Waveform-recording laser altimeter observations of vegetated landscapes provide a time-resolved measure of laser pulse backscatter energy from canopy surfaces and the underlying ground. Airborne laser altimeter waveform data was acquired using the Scanning Lidar Imager of Canopies by Echo Recovery (SLICER) for a successional sequence of four, closed-canopy, deciduous forest stands in eastern Maryland. The four stands were selected so as to include a range of canopy structures of importance to forest ecosystem function, including variation in the height and roughness of the outermost canopy surface and the vertical organization of canopy stories and gaps. The character of the SLICER backscatter signal is described and a method is developed that accounts for occlusion of the laser energy by canopy surfaces, transforming the backscatter signal to a canopy height profile (CHP) that quantitatively represents the relative vertical distribution of canopy surface area. The transformation applies increased weighting to the backscatter amplitude as a function of closure through the canopy and assumes a horizontally random distribution of the canopy components. SLICER CHPs, averaged over areas of overlap where altimeter ground tracks intersect, are shown to be highly reproducible. CHP transects across the four stands reveal spatial variations in vegetation, at the scale of the individual 10-m-diameter laser footprints, within and between stands. Averaged SLICER CHPs are compared to analogous height profile results derived from ground-based sightings to plant intercepts measured on plots within the four stands. The plots were located on the segments of the altimeter ground tracks from which averaged SLICER CHPs were derived, and the ground observations were acquired within 2 weeks of the SLICER data acquisition to minimize temporal change. The differences in canopy structure between the four stands is similarly described by the SLICER and ground-based CHP results. However, a chi-square test of similarity documents differences that are statistically significant. The differences are discussed in terms of measurement properties that define the smoothness of the resulting CHPs and canopy properties that may vertically bias the CHP representations of canopy structure. The statistical differences are most likely due to the more noisy character of the ground-based CHPs, especially high in the canopy where ground-based sightings are rare resulting in an underestimate of canopy surface area and height, and to departures from assumptions of canopy uniformity, particularly regarding lack of clumping and vertically constant canopy reflectance, which bias the CHPs. The results demonstrate that the SLICER observations reliably provide a measure of canopy structure that reveals ecologically interesting structural variations such as those characterizing a successional sequence of closed-canopy, broadleaf forest stands. },

}

R. A. Haugerud and D. J. Harding. SOME ALGORITHMS FOR VIRTUAL DEFORESTATION (VDF) OF LIDAR TOPOGRAPHIC SURVEY DATA. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:211-217, 2001. [WWW ] Keyword(s): lidar, airborne laser scanner, filtering, vegetation, canopy, algorithm, topography, ground surface, virtual deforestation. Abstract:

Lidar topographic surveys of forested terrain generate XYZ positions for laser returns from numerous points, some on the ground and some from vegetation. Extracting a ground surface model from such data requires virtual deforestation (VDF), preferably by automatic means. A simple error budget for lidar topography of forested terrain suggests that the dominant source of error and the greatest room for improvement lies in VDF procedures. We discuss a despike VDF algorithm that classifies returns as ground or not-ground on the basis of the geometry of the surface in the neighborhood of each return. The despike algorithm is fully automatic, effective, and can recover breaklines. It fails to identify some negative blunders, rounds some sharp corners off the landscape, and as implemented is slow. There are clear paths to improve its speed. If multiple-return data are available, a no-multiple-returns VDF algorithm robustly defines areas where all returns are ground returns. Many groups are using variations on block-minimum VDF algorithms, but these do not work well on slopes and typically require substantial human involvement to adjust block size as the fraction of ground returns changes. Fully automatic VDF algorithms are desirable not only to minimize survey costs but also to produce topography for which all necessary interpretive biases and assumptions are explicit. The development of effective VDF algorithms has been hindered by the tendency of some commercial and academic practitioners to keep their work proprietary. Open dialogue is needed.

@Article{haugerud01,
author = {R. A. Haugerud and D. J. Harding },
title = {SOME ALGORITHMS FOR VIRTUAL DEFORESTATION (VDF) OF LIDAR TOPOGRAPHIC SURVEY DATA},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {211-217},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {lidar, airborne laser scanner, filtering, vegetation, canopy, algorithm, topography, ground surface, virtual deforestation},
abstract = {Lidar topographic surveys of forested terrain generate XYZ positions for laser returns from numerous points, some on the ground and some from vegetation. Extracting a ground surface model from such data requires virtual deforestation (VDF), preferably by automatic means. A simple error budget for lidar topography of forested terrain suggests that the dominant source of error and the greatest room for improvement lies in VDF procedures. We discuss a despike VDF algorithm that classifies returns as ground or not-ground on the basis of the geometry of the surface in the neighborhood of each return. The despike algorithm is fully automatic, effective, and can recover breaklines. It fails to identify some negative blunders, rounds some sharp corners off the landscape, and as implemented is slow. There are clear paths to improve its speed. If multiple-return data are available, a no-multiple-returns VDF algorithm robustly defines areas where all returns are ground returns. Many groups are using variations on block-minimum VDF algorithms, but these do not work well on slopes and typically require substantial human involvement to adjust block size as the fraction of ground returns changes. Fully automatic VDF algorithms are desirable not only to minimize survey costs but also to produce topography for which all necessary interpretive biases and assumptions are explicit. The development of effective VDF algorithms has been hindered by the tendency of some commercial and academic practitioners to keep their work proprietary. Open dialogue is needed.},



}

Michelle A. Hofton and J. Bryan Blair. LASER PULSE CORRELATION: A METHOD FOR DETECTING SUBTLE TOPOGRAPHIC CHANGE USING LIDAR RETURN WAVEFORMS. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:181-184, 2001. [WWW ] Keyword(s): LIDAR, laser altimetry, waveforms, natural hazards, surface deformation. Abstract:

We present a technique for using the recorded laser return pulse as a raw observation to detect centimeter-level vertical topographic change from large footprint airborne and spaceborne laser altimetry. We use the correlation of waveforms from coincident footprints as an indication of the similarity in structure of the waveforms from epoch to epoch, and assume that low correlation is an indicator of vertical structure or elevation change. Thus, using vertically and horizontally geolocated waveforms as raw observables (i.e., waveforms tied to a common reference ellipsoid), we assess whether epoch-to-epoch vertical ground motion results in a decrease in the correlation of coincident waveforms over time, and whether this can be used to quantify the magnitude of the deformation. Results of computer models and an example over an area of eroded beachfront are described.

@Article{hofton01a,
author = {Michelle A. Hofton and J. Bryan Blair},
title = {LASER PULSE CORRELATION: A METHOD FOR DETECTING SUBTLE TOPOGRAPHIC CHANGE USING LIDAR RETURN WAVEFORMS},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {181-184},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {LIDAR, laser altimetry, waveforms, natural hazards, surface deformation},
abstract = {We present a technique for using the recorded laser return pulse as a raw observation to detect centimeter-level vertical topographic change from large footprint airborne and spaceborne laser altimetry. We use the correlation of waveforms from coincident footprints as an indication of the similarity in structure of the waveforms from epoch to epoch, and assume that low correlation is an indicator of vertical structure or elevation change. Thus, using vertically and horizontally geolocated waveforms as raw observables (i.e., waveforms tied to a common reference ellipsoid), we assess whether epoch-to-epoch vertical ground motion results in a decrease in the correlation of coincident waveforms over time, and whether this can be used to quantify the magnitude of the deformation. Results of computer models and an example over an area of eroded beachfront are described.},



}

Andrew T. Hudak, Michael A. Lefsky, Warren B. Cohen, and Mercedes Berterretche. INTEGRATION OF LIDAR AND LANDSAT ETM+ DATA. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:95-103, 2001. [WWW ] Keyword(s): regression, kriging, cokriging, sampling, spatial model, geostatistics. Abstract:

Lidar data provide accurate measurements of forest canopy structure in the vertical plane however current lidar sensors have limited coverage in the horizontal plane. Landsat data provide extensive coverage of generalized forest structural classes in the horizontal plane but are relatively insensitive to variation in forest canopy height. It would therefore be desirable to integrate lidar and Landsat data to improve the measurement, mapping, and monitoring of forest structural attributes. We tested five aspatial and spatial methods for predicting canopy height, as measured by an airborne lidar system (Aeroscan), from Landsat ETM+ data: regression, kriging, cokriging, and kriging and cokriging of regression residuals. Our 200 km2 study area in western Oregon encompassed Oregon State University s McDonald-Dunn Research Forest, which is broadly representative of the age and structural classes common in the region. We sampled our continuous lidar coverage in eight systematic patterns to determine which lidar sampling strategy would optimize lidar-Landsat integration: transects sampled at 2000, 1000, 500 and 250 m frequencies, and points sampled at these same spatial frequencies. The aspatial regression model results, regardless of sampling strategy, preserved actual vegetation pattern, but underestimated taller canopies and overestimated shorter canopies. The spatial models, kriging and cokriging, produced less biased results than regression but poorly reproduced vegetation pattern. The integrated models that kriged or cokriged regression residuals were preferable to either the aspatial or spatial models alone, because they preserved the vegetation pattern like regression yet improved estimation accuracies above those predicted from the regression models alone. We concluded that in our study landscape, an integrated modeling strategy is most suitable for estimating and mapping canopy height at locations unsampled by lidar, and that a 250 m point sampling strategy would be more useful for lidar-Landsat ETM+ integration than sparser transect sampling strategies planned for satellite missions.

@Article{hudak01,
author = {Andrew T. Hudak and Michael A. Lefsky and Warren B. Cohen and Mercedes Berterretche },
title = {INTEGRATION OF LIDAR AND LANDSAT ETM+ DATA},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {95-103},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {regression, kriging, cokriging, sampling, spatial model, geostatistics},
abstract = {Lidar data provide accurate measurements of forest canopy structure in the vertical plane however current lidar sensors have limited coverage in the horizontal plane. Landsat data provide extensive coverage of generalized forest structural classes in the horizontal plane but are relatively insensitive to variation in forest canopy height. It would therefore be desirable to integrate lidar and Landsat data to improve the measurement, mapping, and monitoring of forest structural attributes. We tested five aspatial and spatial methods for predicting canopy height, as measured by an airborne lidar system (Aeroscan), from Landsat ETM+ data: regression, kriging, cokriging, and kriging and cokriging of regression residuals. Our 200 km2 study area in western Oregon encompassed Oregon State University s McDonald-Dunn Research Forest, which is broadly representative of the age and structural classes common in the region. We sampled our continuous lidar coverage in eight systematic patterns to determine which lidar sampling strategy would optimize lidar-Landsat integration: transects sampled at 2000, 1000, 500 and 250 m frequencies, and points sampled at these same spatial frequencies. The aspatial regression model results, regardless of sampling strategy, preserved actual vegetation pattern, but underestimated taller canopies and overestimated shorter canopies. The spatial models, kriging and cokriging, produced less biased results than regression but poorly reproduced vegetation pattern. The integrated models that kriged or cokriged regression residuals were preferable to either the aspatial or spatial models alone, because they preserved the vegetation pattern like regression yet improved estimation accuracies above those predicted from the regression models alone. We concluded that in our study landscape, an integrated modeling strategy is most suitable for estimating and mapping canopy height at locations unsampled by lidar, and that a 250 m point sampling strategy would be more useful for lidar-Landsat ETM+ integration than sparser transect sampling strategies planned for satellite missions.},



}

J. Hyyppa, O. Kelle, M. Lehikoinen, and M. Inkinen. A segmentation-based method to retrieve stem volume estimates from 3-D tree height models produced by laser scanners. IEEE Trans. on Geosci. and Remote Sensing, 39(5), 2001.

@article{RefWorks:811,
author={J. Hyyppa and O. Kelle and M. Lehikoinen and M. Inkinen},
year={2001},
title={A segmentation-based method to retrieve stem volume estimates from 3-D tree height models produced by laser scanners},
journal={IEEE Trans. on Geosci. and Remote Sensing},
volume={39},
number={5} 
}

Juha Hyyppae, O. Kelle, and M. Lehikoinen, and M. Inkinen. A segmentation-based method to retrieve stem volume estimates from 3-D tree height models produced by laser scanners. tgars, 39:969-975, 2001. Keyword(s): geophysical techniques, vegetation mapping, forestry, remote sensing by laser beam, optical radar, geophysical measurement technique, laser, remote sensing, airborne lidar, forest inventory, tree trunk, stem volume, biomass forestry, vegetation mapping, three dimensional structure, tree height model, canopy, laser scanner, stem diameter, boreal forest, high pulse rate. Abstract:

In the boreal forest zone and in many forest areas, there exist gaps between the forest crowns. For example, in Finland, more than 30\% of the first pulse data of laser scanning reflect directly from the ground without any interaction with the canopy. By increasing the number of pulses, it is possible to have samples from each individual tree and also from the gaps between the trees. Basically, this means that several laser pulses can be recorded per m/sup 2/. This allows detailed investigation of forest areas and the creation of a three-dimensional (3D) tree height model. Tree height model can be calculated from the digital terrain and crown models both obtained with the laser scanner data. By analyzing the 3D tree height model by using image vision methods, e.g., segmentation, it is possible to locate individual trees, estimate individual tree heights, crown area, and, by using that data, to derive the stem diameter, number of stems, basal area, and stem volume. The advantage of the method is the capability to measure directly physical dimensions from the trees and use that information to calculate the needed stand attributes. This paper demonstrates for the first time that it is possible to accurately estimate standwise forest attributes, especially stem volume (biomass), using high-pulse-rate laser scanners to provide data, from which individual trees can be detected and characteristics of trees such as height, location, and crown dimensions can be determined. That information can be applied to provide estimates for larger areas (stands). Using the new method, the following standard errors were demonstrated for mean height, basal area and stem volume: 1.8 m (9.9\%), 2.0 m/sup 2//ha (10.2\%), and 18.5 m/sup 3//ha (10.5\%), respectively.

@Article{hyyppae_seg01,
author = { Juha Hyyppae and O. Kelle and and M. Lehikoinen and M. Inkinen},
title = { A segmentation-based method to retrieve stem volume estimates from 3-D tree height models produced by laser scanners },
journal = tgars,
year = {2001},
volume = {39},
pages = {969-975},
number = {},
url = {},
keyword = {geophysical techniques; vegetation mapping; forestry; remote sensing by laser beam; optical radar; geophysical measurement technique; laser; remote sensing; airborne lidar; forest inventory; tree trunk; stem volume; biomass forestry; vegetation mapping; three dimensional structure; tree height model; canopy; laser scanner; stem diameter; boreal forest; high pulse rate },
abstract = {In the boreal forest zone and in many forest areas, there exist gaps between the forest crowns. For example, in Finland, more than 30\% of the first pulse data of laser scanning reflect directly from the ground without any interaction with the canopy. By increasing the number of pulses, it is possible to have samples from each individual tree and also from the gaps between the trees. Basically, this means that several laser pulses can be recorded per m/sup 2/. This allows detailed investigation of forest areas and the creation of a three-dimensional (3D) tree height model. Tree height model can be calculated from the digital terrain and crown models both obtained with the laser scanner data. By analyzing the 3D tree height model by using image vision methods, e.g., segmentation, it is possible to locate individual trees, estimate individual tree heights, crown area, and, by using that data, to derive the stem diameter, number of stems, basal area, and stem volume. The advantage of the method is the capability to measure directly physical dimensions from the trees and use that information to calculate the needed stand attributes. This paper demonstrates for the first time that it is possible to accurately estimate standwise forest attributes, especially stem volume (biomass), using high-pulse-rate laser scanners to provide data, from which individual trees can be detected and characteristics of trees such as height, location, and crown dimensions can be determined. That information can be applied to provide estimates for larger areas (stands). Using the new method, the following standard errors were demonstrated for mean height, basal area and stem volume: 1.8 m (9.9\%), 2.0 m/sup 2//ha (10.2\%), and 18.5 m/sup 3//ha (10.5\%), respectively. },



}

K. Kraus and N. Pfeifer. ADVANCED DTM GENERATION FROM LIDAR DATA. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:23-35, 2001. [WWW ] Keyword(s): airborne laser scanner, digital terrain model, interpolation, filtering, break lines. Abstract:

The introduction of laser scanning has triggered o a revolution in topographic terrain capturing, especially in the generation of digital terrain models (DTM). In this article refined methods for the restitution of airborne LIDAR data are presented which have been developed at the Institute of Photogrammetry and Remote Sensing (Institut f¨ur Photogrammetrie und Fernerkundung, I.P.F.) at Vienna University of Technology. First, a technique for the calibration of laser scanner data is introduced. The (height) discrepancies between overlapping strips, as well as control points with known co-ordinates are utilised for a simultaneous adjustment and transformation of all strips into a state wide co-ordinate system. The next step of LIDAR data processing are the filtering (elimination of vegetation and building points, generally o -terrain points) and the interpolation of the (bald earth) surface. The method, developed at the I.P.F., distinguishes itself in the integration of filtering and terrain interpolation in one process (advantage: even in steep terrain ground points are classified correctly) as well as in the application of data pyramids (advantage: even in very dense forest areas and on large buildings, o -terrain points are eliminated). In order to generate a terrain model with high geo-morphological quality, methods are required for deriving structural line information (e.g. break lines) from laser scanner data. The first method which will be presented, proceeds by a simulation of rain fall over the preliminary DTM (water flow analysis). This yields an identification of the pits with their pit base and the outflow (overflow) point. Subsequently, the terrain shape is changed in order to eliminate the pits. In a further method 3D break lines are derived from the original laser scanner points. The precondition is that the ground plan of the break line is known approximately. The result of this step are 3D-splines which are integrated in the hybrid DTM, combining raster and vector data.

@Article{kraus01,
author = {K. Kraus and N. Pfeifer},
title = {ADVANCED DTM GENERATION FROM LIDAR DATA},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {23-35},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {airborne laser scanner, digital terrain model, interpolation, filtering, break lines},
abstract = {The introduction of laser scanning has triggered o a revolution in topographic terrain capturing, especially in the generation of digital terrain models (DTM). In this article refined methods for the restitution of airborne LIDAR data are presented which have been developed at the Institute of Photogrammetry and Remote Sensing (Institut f¨ur Photogrammetrie und Fernerkundung, I.P.F.) at Vienna University of Technology. First, a technique for the calibration of laser scanner data is introduced. The (height) discrepancies between overlapping strips, as well as control points with known co-ordinates are utilised for a simultaneous adjustment and transformation of all strips into a state wide co-ordinate system. The next step of LIDAR data processing are the filtering (elimination of vegetation and building points, generally o -terrain points) and the interpolation of the (bald earth) surface. The method, developed at the I.P.F., distinguishes itself in the integration of filtering and terrain interpolation in one process (advantage: even in steep terrain ground points are classified correctly) as well as in the application of data pyramids (advantage: even in very dense forest areas and on large buildings, o -terrain points are eliminated). In order to generate a terrain model with high geo-morphological quality, methods are required for deriving structural line information (e.g. break lines) from laser scanner data. The first method which will be presented, proceeds by a simulation of rain fall over the preliminary DTM (water flow analysis). This yields an identification of the pits with their pit base and the outflow (overflow) point. Subsequently, the terrain shape is changed in order to eliminate the pits. In a further method 3D break lines are derived from the original laser scanner points. The precondition is that the ground plan of the break line is known approximately. The result of this step are 3D-splines which are integrated in the hybrid DTM, combining raster and vector data.},



}

M.A. Lefsky, Warren B. Cohen, David J. Harding, Geoffery G. Parker, Steven A. Acker, and S. Thomas Gower. Lidar Remote Sensing of Aboveground Biomass in Three Biomes. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:150-160, 2001. [WWW ] Keyword(s): Laser altimetry, lidar, forest, biomass. Abstract:

Estimation of the amount of carbon stored in forests is a key challenge for understanding the global carbon cycle, one which remote sensing is expected to help address. However, direct estimation of carbon storage in moderate to high biomass forests is difficult for conventional optical and radar sensors. Lidar (light detection and ranging) instruments measure the vertical structure of forests and thus hold great promise for remotely sensing the quantity and spatial organization of forest biomass. In this study, we compare the relationships between lidar-measured canopy structure and coincident field measurements of aboveground biomass at sites in the temperate deciduous, temperate coniferous, and boreal coniferous biomes. A single simplified regression for all three sites is compared with equations derived for each site individually. The simplified equation explains 84 $\%$ of variance in aboveground biomass (p<0.0001) and shows no statistically significant bias in its predictions for any individual site.

@Article{lefsky01c,
author = {M.A. Lefsky and Warren B. Cohen and David J. Harding and Geoffery G. Parker and Steven A. Acker and S. Thomas Gower },
title = {Lidar Remote Sensing of Aboveground Biomass in Three Biomes},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {150-160},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Laser altimetry, lidar, forest, biomass},
abstract = {Estimation of the amount of carbon stored in forests is a key challenge for understanding the global carbon cycle, one which remote sensing is expected to help address. However, direct estimation of carbon storage in moderate to high biomass forests is difficult for conventional optical and radar sensors. Lidar (light detection and ranging) instruments measure the vertical structure of forests and thus hold great promise for remotely sensing the quantity and spatial organization of forest biomass. In this study, we compare the relationships between lidar-measured canopy structure and coincident field measurements of aboveground biomass at sites in the temperate deciduous, temperate coniferous, and boreal coniferous biomes. A single simplified regression for all three sites is compared with equations derived for each site individually. The simplified equation explains 84 $\%$ of variance in aboveground biomass (p<0.0001) and shows no statistically significant bias in its predictions for any individual site.},



}

Hans-Gerd Maas. On the use of pulse reflectance data for laserscanner strip adjustment. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:53-65, 2001. [WWW ] Keyword(s): airborne laser scanner, accuracy, pulse reflectance. Abstract:

The precision of airborne laserscanner data is strongly influenced by the limited accuracy potential of the integrated GPS/INS pose determination system. Errors of kinematic GPS height determination will often be in the order of one to two decimeters and propagate directly into the height coordinates of digital surface models, digital terrain models and 3-D object models derived from these data. The planimetric accuracy of ground points is influenced by the kinematic GPS accuracy as well as by drift effects of the INS system and is in the order of a few decimeters. Errors become evident at check points or as discrepancies between neighboring strips of laserscanner data. Vice versa, these discrepancies can be used to apply corrections to laserscanner data in a strip adjustment procedure. Tie points for laserscanner strip adjustment can be determined with high precision by least-squares matching applied to the original non-interpolated ground point clouds organized in stripwise TINs. This procedure provides useful results in regions with sufficient surface slopes in both coordinate directions, but fails over flat terrain if both height and planimetry coordinate discrepancies are to be determined. In such situations, image contrast in the laserscanner pulse reflectance data, simultaneously recorded by some laserscanner systems and perfectly co-registered with the height data in the TIN structure, can replace non-existent height contrast and provide a solution. The paper describes the extension of least-squares-matching to the alternative use of height and reflectance values of irregularly distributed laserscanner points for the determination of laserscanner strip discrepancies in flat regions with existing local image intensity contrast. The practical applicability and precision potential of the technique will be discussed.

@Article{maas01,
author = {Hans-Gerd Maas},
title = {On the use of pulse reflectance data for laserscanner strip adjustment},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {53-65},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {airborne laser scanner, accuracy, pulse reflectance},
abstract = {The precision of airborne laserscanner data is strongly influenced by the limited accuracy potential of the integrated GPS/INS pose determination system. Errors of kinematic GPS height determination will often be in the order of one to two decimeters and propagate directly into the height coordinates of digital surface models, digital terrain models and 3-D object models derived from these data. The planimetric accuracy of ground points is influenced by the kinematic GPS accuracy as well as by drift effects of the INS system and is in the order of a few decimeters. Errors become evident at check points or as discrepancies between neighboring strips of laserscanner data. Vice versa, these discrepancies can be used to apply corrections to laserscanner data in a strip adjustment procedure. Tie points for laserscanner strip adjustment can be determined with high precision by least-squares matching applied to the original non-interpolated ground point clouds organized in stripwise TINs. This procedure provides useful results in regions with sufficient surface slopes in both coordinate directions, but fails over flat terrain if both height and planimetry coordinate discrepancies are to be determined. In such situations, image contrast in the laserscanner pulse reflectance data, simultaneously recorded by some laserscanner systems and perfectly co-registered with the height data in the TIN structure, can replace non-existent height contrast and provide a solution. The paper describes the extension of least-squares-matching to the alternative use of height and reflectance values of irregularly distributed laserscanner points for the determination of laserscanner strip discrepancies in flat regions with existing local image intensity contrast. The practical applicability and precision potential of the technique will be discussed.},



}

Robin D. Morris, Udo von Toussaint, and Peter C. Cheeseman. HIGH RESOLUTION SURFACE GEOMETRY AND ALBEDO BY COMBINING LASER ALTIMETRY AND VISIBLE IMAGES. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:105-111, 2001. [WWW ] Keyword(s): Bayesian inference, surface geometry, albedo, computer vision. Abstract:

The need for accurate geometric and radiometric information over large areas has become increasingly important. Laser al- timetry is one of the key technologies for obtaining this geometric information. However, there are important application areas where the observing platform has its orbit constrained by the other instruments it is carrying, and so the spatial resolution that can be recorded by the laser altimeter is limited. In this paper we show how information recorded by one of the other instruments commonly carried, a high-resolution imaging camera, can be combined with the laser altimeter measurements to give a high resolution estimate both of the surface geometry and its re ectance properties. This estimate has an accuracy unavailable from other interpolation methods. We present the results from combining synthetic laser altimeter measurements on a coarse grid with images generated from a surface model to re-create the surface model.

@Article{morris01,
author = {Robin D. Morris and Udo von Toussaint and Peter C. Cheeseman},
title = {HIGH RESOLUTION SURFACE GEOMETRY AND ALBEDO BY COMBINING LASER ALTIMETRY AND VISIBLE IMAGES},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {105-111},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Bayesian inference, surface geometry, albedo, computer vision},
abstract = {The need for accurate geometric and radiometric information over large areas has become increasingly important. Laser al- timetry is one of the key technologies for obtaining this geometric information. However, there are important application areas where the observing platform has its orbit constrained by the other instruments it is carrying, and so the spatial resolution that can be recorded by the laser altimeter is limited. In this paper we show how information recorded by one of the other instruments commonly carried, a high-resolution imaging camera, can be combined with the laser altimeter measurements to give a high resolution estimate both of the surface geometry and its re ectance properties. This estimate has an accuracy unavailable from other interpolation methods. We present the results from combining synthetic laser altimeter measurements on a coarse grid with images generated from a surface model to re-create the surface model.},



}

Erik Naesset and Kjell-Olav Bjerknes. Estimating tree heights and number of stems in young forest stands using airborne laser scanner data. rse, 78:328-340, 2001. [WWW ] Abstract:

The mean heights of dominant trees and the stem numbers of 39 plots of 200 m2 each were derived from various canopy height metrics and canopy density measured by means of a small-footprint airborne laser scanner over young forest stands with tree heights < 6 m. On the average, the laser transmitted 12,019 pulses ha-1. Ground-truth values were regressed against laser-derived canopy height metrics and density. The regressions explained 83 $\%$ and 42 $\%$ of the variability in ground-truth mean height and stem number, respectively. Crossvalidation of the regressions revealed standard deviations of the differences between predicted and ground-truth values of mean height and stem number of 0.57 m (15 $\%$ ) and 1209 ha-1 (28.8 $\%$ ), respectively. A proposed practical two-stage procedure for prediction of mean height of dominant trees in forest stands was tested. One hundred and seventy-four sample plots were distributed systematically throughout a 1000- ha forest area. Twenty-nine of the plots were sited in young stands with tree heights < 11.5 m. In the first stage, mean height of dominant trees of the 29 plots were regressed against laser-derived canopy height metrics and density. In the second stage, the selected regression was used to predict mean height of 12 selected test stands. The prediction revealed a bias of 0.23 m (3.5 $\%$ ) ( P > .05) and a standard deviation of the differences between predicted and ground-truth mean height of 0.56 m (8.4 $\%$ ).

@Article{naesset01,
author = {Erik Naesset and Kjell-Olav Bjerknes},
title = {Estimating tree heights and number of stems in young forest stands using airborne laser scanner data},
journal = rse,
year = 2001,
volume = 78,
pages = {328-340},
url = {http://www.sciencedirect.com/science/article/B6V6V-44HSYV5-C/1/428d916e61b962ab7766724a9ce8059c},
abstract = {The mean heights of dominant trees and the stem numbers of 39 plots of 200 m2 each were derived from various canopy height metrics and canopy density measured by means of a small-footprint airborne laser scanner over young forest stands with tree heights < 6 m. On the average, the laser transmitted 12,019 pulses ha-1. Ground-truth values were regressed against laser-derived canopy height metrics and density. The regressions explained 83 $\%$ and 42 $\%$ of the variability in ground-truth mean height and stem number, respectively. Crossvalidation of the regressions revealed standard deviations of the differences between predicted and ground-truth values of mean height and stem number of 0.57 m (15 $\%$ ) and 1209 ha-1 (28.8 $\%$ ), respectively. A proposed practical two-stage procedure for prediction of mean height of dominant trees in forest stands was tested. One hundred and seventy-four sample plots were distributed systematically throughout a 1000- ha forest area. Twenty-nine of the plots were sited in young stands with tree heights < 11.5 m. In the first stage, mean height of dominant trees of the 29 plots were regressed against laser-derived canopy height metrics and density. In the second stage, the selected regression was used to predict mean height of 12 selected test stands. The prediction revealed a bias of 0.23 m (3.5 $\%$ ) ( P > .05) and a standard deviation of the differences between predicted and ground-truth mean height of 0.56 m (8.4 $\%$ ).},



}

Wenge Ni-Meister, David L. B. Jupp, and Ralph Dubayah. Modeling Lidar Waveforms in Heterogeneous and Discrete Canopies. tgars, 39(9):1943-1958, 2001. Keyword(s): Geometric optical and radiative transfer (GORT) model, heterogenous plant canopies, lidar waveforms.

@Article{ni01,
author = {Wenge Ni-Meister and David L. B. Jupp and Ralph Dubayah},
title = {Modeling Lidar Waveforms in Heterogeneous and Discrete Canopies},
journal = tgars,
year = {2001},
volume = {39},
pages = {1943-1958},
number = {9},
url = {},
keyword = {Geometric optical and radiative transfer (GORT) model,heterogenous plant canopies, lidar waveforms},
abstract = {},



}

W. Ni-Meister, D. L. B. Jupp, and R. Dubayah. Modeling lidar waveforms in heterogeneous and discrete canopies. Geoscience and Remote Sensing, IEEE Transactions on, 39:1943-1958, 2001. Note: Note: Issue: 9.

@article{RefWorks:830,
author={W. Ni-Meister and D. L. B. Jupp and R. Dubayah},
year={2001},
title={Modeling lidar waveforms in heterogeneous and discrete canopies},
journal={Geoscience and Remote Sensing, IEEE Transactions on},
volume={39},
pages={1943-1958},
note={note: Issue: 9} 
}

Geoffrey G. Parker, Michael A. Lefsky, and David J. Harding. Light transmittance in forest canopies determined using airborne laser altimetry and in-canopy quantum measurements. rse, 76:298-309, 2001. [WWW ] Abstract:

The vertical distribution of light transmittance was derived from field and laser altimeter observations taken in the same canopies of five forests of several ages (young to mature) and canopy types (eastern broadleaved and western tall conifer). Vertical transmittances were derived remotely from the Scanning Lidar Imager of Canopies by Echo Recovery (SLICER) laser altimeter and in the field from measurements of Photosynthetically Active Radiation (PAR) made within the canopy using quantum sensors suspended from the gondola of a tower crane or atop small balloons. Derived numerical characteristics of mean transmittance profiles (the rate of attenuation, whole canopy transmittance, and the radiation-effective height) were similar for both methods across the sites. Measures of the variance and skewness of transmittance also showed similar patterns for corresponding heights between methods. The two methods exhibited greater correspondence in the eastern stands than in the western ones; differences in the interaction between canopy organization and the sensor characteristics between the stand types might explain this. The narrower, more isolated crowns of the western stands permit a deeper penetration into the canopy of nadir-directed laser light than of direct solar radiation from typical elevation angles. Transects of light transmittance in two stands demonstrate that the SLICER sensor can capture meaningful functional variation. Additionally, for one stand with numerous overlapping transects we constructed a three-dimensional view of the transmittance field. Using geostatistics, we demonstrated that the spatial covariance measured in the horizontal plane varied as a function of height. These results suggest a means to remotely assess an important functional characteristic of vegetation, providing a capacity for process-based ecological studies at large scales.

@Article{parker01,
author = {Geoffrey G. Parker and Michael A. Lefsky and David J. Harding},
title = {Light transmittance in forest canopies determined using airborne laser altimetry and in-canopy quantum measurements},
journal = rse,
year = {2001},
volume = {76},
pages = {298-309},
url = {http://www.sciencedirect.com/science/article/B6V6V-43HVM3D-2/1/9b235479eb44bc29503bb850770173c8},
abstract = {The vertical distribution of light transmittance was derived from field and laser altimeter observations taken in the same canopies of five forests of several ages (young to mature) and canopy types (eastern broadleaved and western tall conifer). Vertical transmittances were derived remotely from the Scanning Lidar Imager of Canopies by Echo Recovery (SLICER) laser altimeter and in the field from measurements of Photosynthetically Active Radiation (PAR) made within the canopy using quantum sensors suspended from the gondola of a tower crane or atop small balloons. Derived numerical characteristics of mean transmittance profiles (the rate of attenuation, whole canopy transmittance, and the radiation-effective height) were similar for both methods across the sites. Measures of the variance and skewness of transmittance also showed similar patterns for corresponding heights between methods. The two methods exhibited greater correspondence in the eastern stands than in the western ones; differences in the interaction between canopy organization and the sensor characteristics between the stand types might explain this. The narrower, more isolated crowns of the western stands permit a deeper penetration into the canopy of nadir-directed laser light than of direct solar radiation from typical elevation angles. Transects of light transmittance in two stands demonstrate that the SLICER sensor can capture meaningful functional variation. Additionally, for one stand with numerous overlapping transects we constructed a three-dimensional view of the transmittance field. Using geostatistics, we demonstrated that the spatial covariance measured in the horizontal plane varied as a function of height. These results suggest a means to remotely assess an important functional characteristic of vegetation, providing a capacity for process-based ecological studies at large scales.},



}

G. Parker, M. A. Lefsky, and D. J. Harding. Light transmittance in forest canopies determined using airborne laser altimetry and in-canopy quantum measurements. Remote Sensing of Environment, 76:298-309, 2001.

@article{RefWorks:831,
author={G. Parker and M. A. Lefsky and D. J. Harding},
year={2001},
title={Light transmittance in forest canopies determined using airborne laser altimetry and in-canopy quantum measurements},
journal={Remote Sensing of Environment},
volume={76},
pages={298-309} 
}

B. Peterson, W. Ni-Meister, J.B. Blair, M.A. Hofton, P. Hyde, and R. Dubayah. MODELING LIDAR WAVEFORMS USING A RADIATIVE TRANSFER MODEL. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:121-124, 2001. [WWW ] Keyword(s): Lidar, Radiative transfer modeling, Canopy structure. Abstract:

In the past, obtaining reliable measurements of key forest canopy metrics has been difficult, even after the development of remote sensing technology. Fortunately, next-generation lidar systems are proving to be useful tools for deriving critical canopy measurements, such as height, structure and biomass. These studies have all focused on empirical comparisons between basic lidar-derived and field-sampled measurements. The results of these studies have shown that lidar remote sensing instruments can successfully measure forest canopy characteristics. However, physically-based remote sensing models are necessary to more fully understand and interpret the interactions of the laser energy with the forest canopy. In this study the Geometric Optical and Radiative Transfer (GORT) model is used to model lidar waveforms. GORT is capable of modeling lidar returns from canopies with clumped multiple layers and multiple species. For this study, GORT was used to model waveforms over the Sierra National Forest in California. Field data input into GORT are a representative sample of the different vegetation types found in the forest. The modeled waveforms are then validated against actual lidar data collected by the Laser Vegetation Imaging Sensor (LVIS) which mapped the area in October 1999. By modeling lidar waveforms based on the physical principles of radiative transfer, GORT fills a missing link between the remotely sensed and actual canopy structure. The results of this study will also aid in future large-scale land surface mapping by developing a link between lidar and other remote sensing data.

@Article{peterson01,
author = {B. Peterson and W. Ni-Meister and J.B. Blair and M.A. Hofton and P. Hyde and R. Dubayah},
title = {MODELING LIDAR WAVEFORMS USING A RADIATIVE TRANSFER MODEL},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {121-124},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Lidar, Radiative transfer modeling, Canopy structure},
abstract = {In the past, obtaining reliable measurements of key forest canopy metrics has been difficult, even after the development of remote sensing technology. Fortunately, next-generation lidar systems are proving to be useful tools for deriving critical canopy measurements, such as height, structure and biomass. These studies have all focused on empirical comparisons between basic lidar-derived and field-sampled measurements. The results of these studies have shown that lidar remote sensing instruments can successfully measure forest canopy characteristics. However, physically-based remote sensing models are necessary to more fully understand and interpret the interactions of the laser energy with the forest canopy. In this study the Geometric Optical and Radiative Transfer (GORT) model is used to model lidar waveforms. GORT is capable of modeling lidar returns from canopies with clumped multiple layers and multiple species. For this study, GORT was used to model waveforms over the Sierra National Forest in California. Field data input into GORT are a representative sample of the different vegetation types found in the forest. The modeled waveforms are then validated against actual lidar data collected by the Laser Vegetation Imaging Sensor (LVIS) which mapped the area in October 1999. By modeling lidar waveforms based on the physical principles of radiative transfer, GORT fills a missing link between the remotely sensed and actual canopy structure. The results of this study will also aid in future large-scale land surface mapping by developing a link between lidar and other remote sensing data.},



}

Norbert Pfeifer, Philipp Stadler, and Christian Briese. DERIVATION OF DIGITAL TERRAIN MODELS IN THE SCOP++ ENVIRONMENT. OEEPE Workshop on Airborne Laserscanning and Interferometric SAR for Digital Elevation Models, Stockholm, 2001. [WWW ] Keyword(s): DTM, airborne laser scanner, filtering, classification, SCOP. Abstract:

Airborne laser scanning is widely used for the derivation of terrain information in wooded or open areas but also for the production of building models in cities. For this, the generation of a digital terrain model (DTM) is also required. In this paper the filtering and classification of laser scanner data with iterative robust linear prediction in a hierarchical fashion using data pyramids is described. The coarse-to-fine approach is advantageous because it strengthens the robustness of the method and makes it faster. The results for test data sets of the OEEPE are presented.

@Article{pfeifer01,
author = {Norbert Pfeifer and Philipp Stadler and Christian Briese},
title = {DERIVATION OF DIGITAL TERRAIN MODELS IN THE SCOP++ ENVIRONMENT},
journal = {OEEPE Workshop on Airborne Laserscanning and Interferometric SAR for Digital Elevation Models, Stockholm},
year = {2001},
volume = {},
pages = {},
number = {},
url = {http://www.ipf.tuwien.ac.at/veroeffentlichungen/np_stockholm.pdf},
keyword = {DTM, airborne laser scanner, filtering, classification, SCOP},
abstract = {Airborne laser scanning is widely used for the derivation of terrain information in wooded or open areas but also for the production of building models in cities. For this, the generation of a digital terrain model (DTM) is also required. In this paper the filtering and classification of laser scanner data with iterative robust linear prediction in a hierarchical fashion using data pyramids is described. The coarse-to-fine approach is advantageous because it strengthens the robustness of the method and makes it faster. The results for test data sets of the OEEPE are presented.},



}

Geoff Pickup and Alan Marks. Identification of Floodplains and Estimation of Floodplain Flow Velocities for Sediment Transport Modelling. CSIRO Land and Water, Technical Report, (14/01), July 2001. Note: NOTE: This has a lot of good discussion on how to use DEMs for hydrological modelling.

@article{RefWorks:748,
author={Geoff Pickup and Alan Marks},
year={2001},
month={Jul},
title={Identification of Floodplains and Estimation of Floodplain Flow Velocities for Sediment Transport Modelling},
journal={CSIRO Land and Water, Technical Report},
number={14/01},
note={NOTE: This has a lot of good discussion on how to use DEMs for hydrological modelling.} 
}

Marco Roggero. AIRBORNE LASER SCANNING: CLUSTERING IN RAW DATA. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:227-232, 2001. [WWW ] Keyword(s): airborne laser scanner, clustering, DTM extraction, entity extraction.. Abstract:

We implemented a strategy for terrain, vegetation and building detection, based on laser range data only. The result was obtained by working on raw data, so we were able to take advantage of the full resolution potential of laser scanning. The detection of objects was performed in two stages: first, elevated objects and ground are separated, and then the objects are classified as vegetation or buildings. Work is still in progress, about the extraction and classification of entities. A comparative analysis of the first pulse, the last pulse and intensity data can improve the result of clustering. Results obtained in different environments with one-meter grid laser data are shown; we have tested the algorithm on city areas, countryside, river bed, landslides, mountains and wooded terrain.

@Article{roggero01,
author = {Marco Roggero},
title = {AIRBORNE LASER SCANNING: CLUSTERING IN RAW DATA},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {227-232},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {airborne laser scanner, clustering, DTM extraction, entity extraction.},
abstract = {We implemented a strategy for terrain, vegetation and building detection, based on laser range data only. The result was obtained by working on raw data, so we were able to take advantage of the full resolution potential of laser scanning. The detection of objects was performed in two stages: first, elevated objects and ground are separated, and then the objects are classified as vegetation or buildings. Work is still in progress, about the extraction and classification of entities. A comparative analysis of the first pulse, the last pulse and intensity data can improve the result of clustering. Results obtained in different environments with one-meter grid laser data are shown; we have tested the algorithm on city areas, countryside, river bed, landslides, mountains and wooded terrain.},



}

Toni Schenk, Suyoung Seo, and Beata Csatho. ACCURACY STUDY OF AIRBORNE LASER SCANNING DATA WITH PHOTOGRAMMETRY. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:113-118, 2001. [WWW ] Keyword(s): Photogrammetry, Laser Ranging, DTM generation, Surface Reconstruction, Calibration, Segmentation, Fusion. Abstract:

This paper describes an accuracy study of airborne laser scanning data obtained by the Airborne Topographic Mapper (ATM) laser system over Ocean City, Md. The ATM is a conical scanning laser altimeter developed by NASA for precise measurement of surface elevation changes in polar ice sheets, ocean beaches and drainage systems. First, we determine the internal accuracy of the system by comparing data from different flight missions. This is followed by a comparison of the merged laser data sets with surface elevations obtained by photogrammetry. Large-scale aerial photographs have been acquired over the test area and an aerial triangulation was performed to determine the exterior orientation parameters. The comparison consists of several experiments that were performed with the digitized photographs and the laser points. First we determine how well the laser points agree with the visible surface as defined by two overlapping images (stereopsis). This is accomplished by backprojecting the laser points to the images based on their exterior orientation parameters. The location of the laser points in the images serve as initial approximations for image matching. We use an adaptive least-squares matching procedure with a variable template size. A non-zero matching vector indicates discrepancies between laser points and photogrammetry. The purpose of the second experiment is to estimate the horizontal accuracy of laser points. One way to accomplish this is to extract linear features and to compare them. Linear features in laser point data sets can only be determined indirectly, e.g. by intersecting planar surface patches. In contrast, linear features in aerial images can be determined directly by an edge operator. We used the Canny operator to extract edges in the images and feature-based matching to find corresponding edges in the stereopair. After describing the procedure, experimental results are reported.

@Article{schenk01,
author = {Toni Schenk and Suyoung Seo and Beata Csatho},
title = {ACCURACY STUDY OF AIRBORNE LASER SCANNING DATA WITH PHOTOGRAMMETRY},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {113-118},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Photogrammetry, Laser Ranging, DTM generation, Surface Reconstruction, Calibration, Segmentation, Fusion},
abstract = {This paper describes an accuracy study of airborne laser scanning data obtained by the Airborne Topographic Mapper (ATM) laser system over Ocean City, Md. The ATM is a conical scanning laser altimeter developed by NASA for precise measurement of surface elevation changes in polar ice sheets, ocean beaches and drainage systems. First, we determine the internal accuracy of the system by comparing data from different flight missions. This is followed by a comparison of the merged laser data sets with surface elevations obtained by photogrammetry. Large-scale aerial photographs have been acquired over the test area and an aerial triangulation was performed to determine the exterior orientation parameters. The comparison consists of several experiments that were performed with the digitized photographs and the laser points. First we determine how well the laser points agree with the visible surface as defined by two overlapping images (stereopsis). This is accomplished by backprojecting the laser points to the images based on their exterior orientation parameters. The location of the laser points in the images serve as initial approximations for image matching. We use an adaptive least-squares matching procedure with a variable template size. A non-zero matching vector indicates discrepancies between laser points and photogrammetry. The purpose of the second experiment is to estimate the horizontal accuracy of laser points. One way to accomplish this is to extract linear features and to compare them. Linear features in laser point data sets can only be determined indirectly, e.g. by intersecting planar surface patches. In contrast, linear features in aerial images can be determined directly by an edge operator. We used the Canny operator to extract edges in the images and feature-based matching to find corresponding edges in the stereopair. After describing the procedure, experimental results are reported.},

}

Jochen Schiewe. Ein regionen-basiertes Verfahren zur Extraktion der Geländeoberfläche aus Digitalen Oberflächen-Modellen. Photogrammetrie Fernerkundung Geoinformation, pp 81-90, 2001. [WWW ]

@Article{schiewe01,
author = {Jochen Schiewe},
title = {Ein regionen-basiertes Verfahren zur Extraktion der Gel\"andeoberfl\"ache aus Digitalen Oberfl\"achen-Modellen},
journal = {Photogrammetrie Fernerkundung Geoinformation},
year = {2001},
volume = {},
pages = {81-90},
number = {},
url = {http://www.iuw.uni-vechta.de/personal/geoinf/jochen/},
keyword = {},
abstract = {},



}

K. C. Slatton, M. M. Crawford, and B. L. Evans. Fusing Interferometric Radar and Laser Altimeter Data to Estimate Surface Topography and Vegetation Heights. TGARS, 39(11):2470-2482, November 2001. Note: NOTE: This is the first place that I really put the MKS and NLO fusion down on paper. Note. I used the label SCE00b initially to reference it while it was in review. Now that it's in print, it should be SCE01. However, many old documents still call it using SCE00b, so I'll just copy it and use the second label.

@article{RefWorks:716,
author={K. C. Slatton and M. M. Crawford and B. L. Evans},
year={2001},
month={Nov},
title={Fusing Interferometric Radar and Laser Altimeter Data to Estimate Surface Topography and Vegetation Heights},
journal={TGARS},
volume={39},
number={11},
pages={2470-2482},
note={NOTE: This is the first place that I really put the MKS and NLO fusion down on paper. Note. I used the label "SCE00b" initially to reference it while it was in review. Now that it's in print, it should be "SCE01". However, many old documents still call it using "SCE00b", so I'll just copy it and use the second label.} 
}

@article{RefWorks:717,
author={K. C. Slatton and M. M. Crawford and B. L. Evans},
year={2001},
month={Nov},
title={Fusing Interferometric Radar and Laser Altimeter Data to Estimate Surface Topography and Vegetation Heights},
journal={TGARS},
volume={39},
number={11},
pages={2470-2482},
note={NOTE: This is just a copy of "SCE00b" with an updated label for "\cite" callouts.} 
}

K. C. Slatton, M. M. Crawford, and B. L. Evans. Fusing Interferometric Radar and Laser Altimeter Data to Estimate Surface Topography and Vegetation Heights. IEEE Transactions on Geoscience and Remote Sensing, 39(11):2470-2482, November 2001.

@article{RefWorks:840,
author={K. C. Slatton and M. M. Crawford and B. L. Evans},
year={2001},
month={Nov},
title={Fusing Interferometric Radar and Laser Altimeter Data to Estimate Surface Topography and Vegetation Heights},
journal={IEEE Transactions on Geoscience and Remote Sensing},
volume={39},
number={11},
pages={2470-2482} 
}

Benoit A. St-Onge and Nora Achaichia. MEASURING FOREST CANOPY HEIGHT USING A COMBINATION OF LIDAR AND AERIAL PHOTOGRAPHY DATA. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:131-137, 2001. [WWW ] Keyword(s): lidar, photogrammetry, forest, aerial photography, canopy height. Abstract:

It has been demonstrated that the height of forest canopies can be measured with a good accuracy using small footprint lidars. This is essentially accomplished by subtracting the last return altitude (ground) from the corresponding first return altitude (canopy surface). The technique is considered superior to photogrammetric methods mainly because the ground level, which is difficult to see on aerial photos of densely forested areas, can be well identified using small footprint lidars. However, lidar cannot be used to characterized past forest states, while these can be assessed, and photogrammetically measured, in the wealth of historical aerial photographs most developed countries possess. Our goal is to replace the first return lidar data by altitude models derived from aerial photos in order to map forest canopy height changes of the past decades. This paper presents the first methodological steps which consist in comparing canopy heights obtained from lidar data only to a combination of lidar and photogrammetry data. The lidar data was acquired over an area of the boreal forest in Quebec, Canada, in 1998, using Optech s ALTM1020 flying at an altitude of 700 m. Two stereo-pairs of aerial black and white photographs were used: 1) a pair of 1:15,000 photos taken in 1994, and 2) a pair of 1:40,000 photos taken in 1998. A lidar canopy height model (CHM) was created by subtracting ground altitudes from canopy altitudes. Aerial photo altitude models were derived using the image correlation methods of Virtuozo 3.2 software. The ground level altitudinal fit between the aerial photo altitude model and the lidar data was checked on rock outcrops. A photo CHM was created by subtracting the lidar ground altitude model from the aerial photo altitude model. The photo CHM and the lidar CHM show a good degree of correlation.

@Article{stonge01,
author = {Benoit A. St-Onge and Nora Achaichia},
title = {MEASURING FOREST CANOPY HEIGHT USING A COMBINATION OF LIDAR AND AERIAL PHOTOGRAPHY DATA},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {131-137},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {lidar, photogrammetry, forest, aerial photography, canopy height},
abstract = {It has been demonstrated that the height of forest canopies can be measured with a good accuracy using small footprint lidars. This is essentially accomplished by subtracting the last return altitude (ground) from the corresponding first return altitude (canopy surface). The technique is considered superior to photogrammetric methods mainly because the ground level, which is difficult to see on aerial photos of densely forested areas, can be well identified using small footprint lidars. However, lidar cannot be used to characterized past forest states, while these can be assessed, and photogrammetically measured, in the wealth of historical aerial photographs most developed countries possess. Our goal is to replace the first return lidar data by altitude models derived from aerial photos in order to map forest canopy height changes of the past decades. This paper presents the first methodological steps which consist in comparing canopy heights obtained from lidar data only to a combination of lidar and photogrammetry data. The lidar data was acquired over an area of the boreal forest in Quebec, Canada, in 1998, using Optech s ALTM1020 flying at an altitude of 700 m. Two stereo-pairs of aerial black and white photographs were used: 1) a pair of 1:15,000 photos taken in 1994, and 2) a pair of 1:40,000 photos taken in 1998. A lidar canopy height model (CHM) was created by subtracting ground altitudes from canopy altitudes. Aerial photo altitude models were derived using the image correlation methods of Virtuozo 3.2 software. The ground level altitudinal fit between the aerial photo altitude model and the lidar data was checked on rock outcrops. A photo CHM was created by subtracting the lidar ground altitude model from the aerial photo altitude model. The photo CHM and the lidar CHM show a good degree of correlation.},



}

Edward Verbree and Peter van Oosterom. Scanline forced Delaunay TENs for surface representation. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:45-51, 2001. [WWW ] Keyword(s): Delaunay Tetrahedron Networks (TEN), TIN, Surface reconstruction. Abstract:

The general idea that a Delaunay TIN (DT) is more appropriate than non-Delaunay TINs, due to better shaped triangles, might be true for many applications, but not for height dependent analytical queries. This is because the distribution of the triangle tessellation is defined in the two-dimensional XY-plane, by ignoring the Z-value in the Delaunay empty circum circle criterion. Alternatively, Data Dependent Triangulations (DDT) aim to identify which triangulation of a given function z=f(x,y) over a given set of points will optimize some quality, i.e. the minimal spatial area of the surface or the volume below the resulting surface. This might be a good approach, but still there is no certainty the TIN represents the actual surface. Besides that, a 2D-TIN (Delaunay or not) is only capable to solve 2D (or 2.5D) data distributions. The reconstruction of the surface given by a set of surface points alone is therefore not unambiguous. This paper describes a surface reconstruction method based on the scanlines, the lines-of-sight or measurements between the observer (or the measurement platform) and the target (the measured point). As the scanlines do not belong to the surface, we have to use a real 3D triangulation construction method, resulting in a Tetrahedronized Irregular Network. This TEN is capable to store all kinds of surfacefeatures (as the target-points) and the scanlines as well. The scanlines are forced to split by adding Steiner points until they are part of the Delaunay TEN. This procedure gives us the additional information needed to use the TEN to reconstruct the surface. The method is demonstrated by the non-trivial case of a set of measured points in a regular square distribution showing the improved surface reconstruction technique.

@Article{verbree01,
author = {Edward Verbree and Peter van Oosterom},
title = {Scanline forced Delaunay TENs for surface representation},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {45-51},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Delaunay Tetrahedron Networks (TEN), TIN, Surface reconstruction},
abstract = {The general idea that a Delaunay TIN (DT) is more appropriate than non-Delaunay TINs, due to better shaped triangles, might be true for many applications, but not for height dependent analytical queries. This is because the distribution of the triangle tessellation is defined in the two-dimensional XY-plane, by ignoring the Z-value in the Delaunay empty circum circle criterion. Alternatively, Data Dependent Triangulations (DDT) aim to identify which triangulation of a given function z=f(x,y) over a given set of points will optimize some quality, i.e. the minimal spatial area of the surface or the volume below the resulting surface. This might be a good approach, but still there is no certainty the TIN represents the actual surface. Besides that, a 2D-TIN (Delaunay or not) is only capable to solve 2D (or 2.5D) data distributions. The reconstruction of the surface given by a set of surface points alone is therefore not unambiguous. This paper describes a surface reconstruction method based on the scanlines, the lines-of-sight or measurements between the observer (or the measurement platform) and the target (the measured point). As the scanlines do not belong to the surface, we have to use a real 3D triangulation construction method, resulting in a Tetrahedronized Irregular Network. This TEN is capable to store all kinds of surfacefeatures (as the target-points) and the scanlines as well. The scanlines are forced to split by adding Steiner points until they are part of the Delaunay TEN. This procedure gives us the additional information needed to use the TEN to reconstruct the surface. The method is demonstrated by the non-trivial case of a set of measured points in a regular square distribution showing the improved surface reconstruction technique.},



}

George Vosselman and Sander Dijkman. 3D BUILDING MODEL RECONSTRUCTION FROM POINT CLOUDS AND GROUND PLANS. International Archives of Photogrammetry and Remote Sensing, XXXIV-3/W4:37-43, 2001. [WWW ] Keyword(s): Building reconstruction, laser altimetry, Hough transform. Abstract:

Airborne laser altimetry has become a very popular technique for the acquisition of digital elevation models. The high point density that can be achieved with this technique enables applications of laser data for many other purposes. This paper deals with the construction of 3D models of the urban environment. A three-dimensional version of the well-known Hough transform is used for the extraction of planar faces from the irregularly distributed point clouds. To support the 3D reconstruction usage is made of available ground plans of the buildings. Two different strategies are explored to reconstruct building models from the detected planar faces and segmented ground plans. Whereas the first strategy tries to detect intersection lines and height jump edges, the second one assumes that all detected planar faces should model some part of the building. Experiments show that the second strategy is able to reconstruct more buildings and more details of this buildings, but that it sometimes leads to additional parts of the model that do not exist. When restricted to buildings with rectangular segments of the ground plan, the second strategy was able to reconstruct 83 buildings out of a dataset with 94 buildings.

@Article{vosselman01,
author = {George Vosselman and Sander Dijkman},
title = {3D BUILDING MODEL RECONSTRUCTION FROM POINT CLOUDS AND GROUND PLANS},
journal = {International Archives of Photogrammetry and Remote Sensing},
year = {2001},
volume = {XXXIV-3/W4},
pages = {37-43},
number = {},
url = {http://lvis.gsfc.nasa.gov/ws_proceedings.html},
keyword = {Building reconstruction, laser altimetry, Hough transform},
abstract = {Airborne laser altimetry has become a very popular technique for the acquisition of digital elevation models. The high point density that can be achieved with this technique enables applications of laser data for many other purposes. This paper deals with the construction of 3D models of the urban environment. A three-dimensional version of the well-known Hough transform is used for the extraction of planar faces from the irregularly distributed point clouds. To support the 3D reconstruction usage is made of available ground plans of the buildings. Two different strategies are explored to reconstruct building models from the detected planar faces and segmented ground plans. Whereas the first strategy tries to detect intersection lines and height jump edges, the second one assumes that all detected planar faces should model some part of the building. Experiments show that the second strategy is able to reconstruct more buildings and more details of this buildings, but that it sometimes leads to additional parts of the model that do not exist. When restricted to buildings with rectangular segments of the ground plan, the second strategy was able to reconstruct 83 buildings out of a dataset with 94 buildings.},



}

T.Thuy Vu and Mitsuharu Tokunaga. Wavelet and Scale-Space Theory in Segmentation of Airborne Laser Scanner Data. Proc. ACRS 2001 - 22nd Asian Conference on Remote Sensing, 1:176-180, 2001. [WWW ] Keyword(s): Wavelet, Airborne Laser Scanner, Segmentation.

@Article{vu01,
author = {T.Thuy Vu and Mitsuharu Tokunaga},
title = {Wavelet and Scale-Space Theory in Segmentation of Airborne Laser Scanner Data},
journal = {Proc. ACRS 2001 - 22nd Asian Conference on Remote Sensing},
year = {2001},
volume = {1},
pages = {176-180},
keyword = {Wavelet, Airborne Laser Scanner, Segmentation},
url = {http://www.crisp.nus.edu.sg/~acrs2001/pdf/037VU.PDF},
abstract = {},



}

Conference articles

Hans-Erik Andersen, Stephen E. Reutebuch, and Gerard F. Schreuder. Automated Individual Tree Measurement through Morphological Analysis of a LIDAR-based Canopy Surface Model. In , 2001. Abstract:

An algorithm for automated individual tree measurement was developed that is driven by a morphological analysis of a high-resolution LIDAR-based canopy surface model. Binary and grayscale mathematical morphology was used to relate structure within a three-dimensional forest canopy model to the location of individual tree crown apexes. This information was used to extract LIDAR measurements of individual tree position and height. Algorithm measurements were compared to photogrammetric measurements from large (1:3000) scale aerial photography. Given a range of optimal input parameters, the algorithm was successful in locating and measuring individual tree crowns. The algorithm identified individual tree crown apexes in a mature forest with closed canopy within 2 meters of photogrammetrically-measured crown apexes with a User s accuracy of 89 $\%$ and a Producer s accuracy of 83 $\%$ . With another set of input parameters, the algorithm identified tree crown apexes in a younger stand with dense, closed canopy within 2 meters of photogrammetrically-measured crown apexes with a User s accuracy of 84 $\%$ and a Producer s accuracy of 82 $\%$ . The difference between algorithm and photogrammetric tree crown apex height measurements was approximately 1 meter in both study areas.

@inproceedings{andersen01,
author = {Hans-Erik Andersen and Stephen E. Reutebuch and Gerard F. Schreuder},
title = {Automated Individual Tree Measurement through Morphological Analysis of a LIDAR-based Canopy Surface Model},
journal = {},
year = {2001},
volume = {},
abstract = { An algorithm for automated individual tree measurement was developed that is driven by a morphological analysis of a high-resolution LIDAR-based canopy surface model. Binary and grayscale mathematical morphology was used to relate structure within a three-dimensional forest canopy model to the location of individual tree crown apexes. This information was used to extract LIDAR measurements of individual tree position and height. Algorithm measurements were compared to photogrammetric measurements from large (1:3000) scale aerial photography. Given a range of optimal input parameters, the algorithm was successful in locating and measuring individual tree crowns. The algorithm identified individual tree crown apexes in a mature forest with closed canopy within 2 meters of photogrammetrically-measured crown apexes with a User s accuracy of 89 $\%$ and a Producer s accuracy of 83 $\%$ . With another set of input parameters, the algorithm identified tree crown apexes in a younger stand with dense, closed canopy within 2 meters of photogrammetrically-measured crown apexes with a User s accuracy of 84 $\%$ and a Producer s accuracy of 82 $\%$ . The difference between algorithm and photogrammetric tree crown apex height measurements was approximately 1 meter in both study areas.},
pages = {},



}

K. C. Slatton, M. M. Crawford, and B. L. Evans. Multiscale Adaptive Estimation for Fusing Interferometric Radar and Laser Altimeter Data. In Anonymous, editor, , volume 2, pages 879-881, 2001.

@inproceedings{RefWorks:841,
author={K. C. Slatton and M. M. Crawford and B. L. Evans},
editor={Anonymous },
year={2001},
title={Multiscale Adaptive Estimation for Fusing Interferometric Radar and Laser Altimeter Data},
volume={2},
pages={879-881} 
}

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Last modified: Thu Jan 27 00:57:26 2005
Author: Kuei-Tsung Shih.

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