Measuring tree stem diameters using intensity profiles from ground-based scanning lidar from a fixed viewpoint
Measuring tree stem diameters using intensity profiles from ground-based scanning lidar from a fixed viewpoint
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DOI：
10.1016/j.isprsjprs.2010.08.006
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发表时间：
2011-01-01
影响因子：
12.7
通讯作者：
Culvenor, D. S.
中科院分区：
文献类型：
--
作者：
Lovell, J. L.;Jupp, D. L. B.;Culvenor, D. S.
本文提出了一种利用单视点扫描光探测和测距（激光雷达）系统的回波强度来识别森林内树干的位置和测量树干直径的方法。这些仪器正用于快速森林清查，并为机载激光雷达提供一致的辅助资料。发现树干上的强度样条与由树干的范围和直径参数化的简单模型一致。通过将模型拟合到横断面数据中，计算出阀杆直径。阀杆的角跨度也可以通过使用一个简单的阈值来估计，其中强度值是针对给定直径的阀杆的预期强度进行测试的。当数据不足以拟合模型或部分模糊时，这是有用的。识别树木位置和树干直径的过程是完全自动化的，并且被证明能够成功地识别大部分树木，包括一些部分被遮挡在视野之外的树木。测量范围和对树木的方位与现场数据非常吻合。在样地尺度上，树干角跨度和直径估算值与实地测量值具有良好的相关性。发现直径估计的精度随着扫描位置的距离而降低，并且对于仪器的小角度（小于扫描分辨率的两倍）的杆也会降低。一种调整测量结果以补偿由于扫描点遮挡而遗漏的树木的方法和使用角度计数方法可以改善基础面积估算，并在4%的现场测量范围内实现一致性。(C) 2010国际摄影测量与遥感学会（ISPRS）Elsevier B.V.版权所有。
This paper presents a method for using the intensity of returns from a scanning light detection and ranging (lidar) system from a single viewing point to identify the location and measure the diameter of tree stems within a forest. Such instruments are being used for rapid forest inventory and to provide consistent supporting information for airborne lidars. The intensity transect across a tree stem is found to be consistent with a simple model parameterised by the range and diameter of the trunk. The stem diameter is calculated by fitting the model to transect data. The angular span of the stem can also be estimated by using a simple threshold where intensity values are tested against the expected intensity for a stem of given diameter. This is useful when data are insufficient to fit the model or the stem is partially obscured. The process of identifying tree positions and trunk diameters is fully automated and is shown to be successful in identifying a high proportion of trees, including some that are partially obscured from view. The range and bearing to trees are in excellent agreement with field data. Trunk angular span and diameter estimations are well correlated with field measurements at the plot scale. The accuracy of diameter estimation is found to decrease with range from the scanning position and is also reduced for stems subtending small angles (less than twice the scanning resolution) to the instrument. A method for adjusting survey results to compensate for trees missed due to obscuration from the scanning point and the use of angle count methods is found to improve basal area estimates and achieve agreement within 4% of field measurements. (C) 2010 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS). Published by Elsevier B.V. All rights reserved.