REFERENCE VALUE PROVISION SCHEMES FOR ATTENUATION CORRECTION OF FULL-WAVEFORM AIRBORNE LASER SCANNER DATA
The characterization of the vertical forest structure is highly relevant for ecological research and for better understanding forest ecosystems. Full-waveform airborne laser scanner systems providing a complete time-resolved digitization of every laser pulse echo may deliver very valuable informatio...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-08-01
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| Series: | ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | http://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/II-3-W5/65/2015/isprsannals-II-3-W5-65-2015.pdf |
| Summary: | The characterization of the vertical forest structure is highly relevant for ecological research and for better understanding forest ecosystems.
Full-waveform airborne laser scanner systems providing a complete time-resolved digitization of every laser pulse echo may
deliver very valuable information on the biophysical structure in forest stands. To exploit the great potential offered by full-waveform
airborne laser scanning data, the development of suitable voxel based data analysis methods is straightforward. Beyond extracting
additional 3D points, it is very promising to derive voxel attributes from the digitized waveform directly. However, the ’history’ of each
laser pulse echo is characterized by attenuation effects caused by reflections in higher regions of the crown. As a result, the received
waveform signals within the canopy have a lower amplitude than it would be observed for an identical structure without the previous
canopy structure interactions (Romanczyk et al., 2012).
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To achieve a radiometrically correct voxel space representation, the loss of signal strength caused by partial reflections on the path
of a laser pulse through the canopy has to be compensated by applying suitable attenuation correction models. The basic idea of the
correction procedure is to enhance the waveform intensity values in lower parts of the canopy for portions of the pulse intensity, which
have been reflected in higher parts of the canopy. To estimate the enhancement factor an appropriate reference value has to be derived
from the data itself. Based on pulse history correction schemes presented in previous publications, the paper will discuss several
approaches for reference value estimation. Furthermore, the results of experiments with two different data sets (leaf-on/leaf-off) are
presented. |
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| ISSN: | 2194-9042 2194-9050 |