CHM与DSM相结合的无人机激光雷达单木分割  

Individual Tree Segmentation of UAV-LiDAR Based on the Combination of CHM and DSM

作　　者：胡中洋 陕亮 陈翔宇 余坤勇 刘健 Hu Zhongyang;Shan Liang;Chen Xiangyu;Yu Kunyong;Liu Jian(College of Forestry Fujian Agriculture and Forestry University Fujian Province Key Laboratory of 3S Technology and Optimal Utilization of Resources,Fuzhou 350002)

机构地区：[1]福建农林大学林学院3S技术与资源优化利用福建省高等学校重点实验室,福州350002

出　　处：《林业科学》2024年第8期14-24,共11页Scientia Silvae Sinicae

基　　金：国家自然科学基金项目(32271876);福建省林业局科技计划项目(2022FKJ03)。

摘　　要：【目的】提出一种冠层高度模型(CHM)与数字表面模型(DSM)相结合的单木分割方法,以解决无人机激光雷达提取地形坡度较大区域CHM时因树冠形变导致单木分割精度降低的问题。【方法】利用无人机激光雷达数据,在福建省顺昌县洋口林场地形起伏较大的中、高郁闭度杉木人工林中选择中龄林和幼龄林各3块标准地,结合地面实测数据和目视解译方法,对CHM与DSM相结合(优化方法)的4种窗口的局部最大值法的树顶点探测和极值标记的分水岭算法的单木分割进行精度评价,并与仅基于CHM的传统方法的树顶点探测和单木分割进行对比分析。【结果】树顶点探测方面,随着窗口增大,每块样地探测的单木总数量和探测百分比均呈下降趋势;中龄林3块样地的最佳窗口为0.3 m,幼龄林3块样地的最佳窗口为0.2 m,此时6块样地1∶1对应关系的单木数量和生产者精度均最大;在相应最佳窗口条件下,仅基于CHM的局部最大值法因树冠形变存在容易产生单木多树顶点探测现象,传统方法的单木探测百分比高于优化方法,但传统方法的树顶点探测精度低于优化方法。幼龄林的树顶点探测精度高于中龄林,这是因为幼龄林样地冠幅和单木相邻距离更一致,更适应固定窗口的局部最大值法。单木分割方面,优化方法的单木分割精度高于传统方法,幼龄林的单木分割精度高于中龄林。【结论】局部最大值法的树顶点探测和分水岭算法的单木分割直接数据源为DSM,是树冠表面真实起伏状况的反映,没有树冠形变,研究结果为更真实的树顶点和单木树冠边界。CHM与DSM相结合的单木分割方法在中、高郁闭度杉木人工中、幼林中分割精度较高(6块样地探测率r均大于88%,准确率p均大于92%,F得分均大于91%),将该方法集成在ArcGIS模型构建器中,可为精准化、自动化、集成化的无人机激光雷达单木分割应用提供可�【Objective】Considering that the unmanned aerial vehicle(UAV)LiDAR-derived canopy height model(CHM)is prone to distortion in areas with complex terrain,which significantly limits the accuracy of the individual tree segmentation,this study aims to propose a new method that utilizes the combination of CHM and digital surface model(DSM)to segment individual tree.【Method】By using UAV-LiDAR data and choosing 3 standard plots of middle-aged forest and young forest in steep areas of Cunninghamia lanceolata plantation with middle and high crown density in Yangkou forest farm,Shunchang country,Fujian Province,this paper used the field-measured and visual interpretation data to calculate and analyze the accuracy of treetop detection and individual tree segmentation which were acquired by using local maximum algorithm with 4 fixed window size and extremum controlling watershed algorithm based on the combination of CHM and DSM and compared them with the traditional method of using CHM alone.【Result】In the matter of treetop detection,number of detecting treetops and detection percentage for each plot showed a downward trend with window size increasing;The optimal window size of 3 middle-aged forest plots is 0.3 m and the optimal window size of 3 young forest plots is 0.2 m.In this configuration,the individual tree of one-to-one correspondence and the producer’s accuracy are the maxima.By using the CHM alone,the detection percentage are higher but the accuracy of treetop detection are lower than using the combination of CHM and DSM because the CHM-based local maximum method is prone to multiple detecting treetops in the individual tree on the optimal window size.The accuracy of treetop detection in the young forest plots are higher than in the middle-aged forest plots.The reason is that the crown breadth and adjacent distance of individual trees in the young forest plots are more consistent which is more adapted to the local maximum algorithm.In the matter of individual tree segmentation,on the optimal window size

关 键 词：激光雷达 单木分割 分水岭算法 冠层高度模型 数字表面模型 

分 类 号：S757[农业科学—森林经理学]