REFERENCE VALUE PROVISION SCHEMES FOR ATTENUATION CORRECTION OF FULL-WAVEFORM AIRBORNE LASER SCANNER DATA
REFERENCE VALUE PROVISION SCHEMES FOR ATTENUATION CORRECTION OF FULL-WAVEFORM AIRBORNE LASER SCANNER DATA
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DOI：
10.5194/isprsannals-ii-3-w5-65-2015
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
K. Richter;R. Blaskow;N. Stelling;H. Maas
中科院分区：
文献类型：
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作者：
K. Richter;R. Blaskow;N. Stelling;H. Maas
抽象的。垂直森林结构的表征对于生态研究和更好地了解森林生态系统高度相关。全波形机载激光扫描仪系统对每个激光脉冲回波进行完整的时间分辨数字化，可以提供有关林分生物物理结构的非常有价值的信息。为了开发全波形机载激光扫描数据所提供的巨大潜力，开发合适的基于体素的数据分析方法非常简单。除了提取额外的 3D 点之外，直接从数字化波形中导出体素属性也是非常有前途的。然而，每个激光脉冲回波的“历史”的特点是由牙冠较高区域的反射引起的衰减效应。因此，冠层内接收到的波形信号的幅度低于在没有先前冠层结构相互作用的情况下观察到的相同结构的幅度（Romanczyk 等人，2012）。为了实现辐射测量正确的体素空间表示，必须通过应用合适的衰减校正模型来补偿由激光脉冲穿过冠层的路径上的部分反射引起的信号强度损失。校正过程的基本思想是针对已在冠层较高部分中反映的部分脉冲强度增强冠层较低部分中的波形强度值。为了估计增强因子，必须从数据本身得出适当的参考值。基于之前出版物中提出的脉冲历史校正方案，本文将讨论几种参考值估计方法。此外，还提供了两个不同数据集（叶上/叶下）的实验结果。
Abstract. 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). 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.