南京林业大学学报(自然科学版) ›› 2024, Vol. 48 ›› Issue (4): 113-122.doi: 10.12302/j.issn.1000-2006.202206035

所属专题: 专题报道Ⅲ:智慧林业之森林可视化研究

• 专题报道Ⅲ:智慧林业之森林可视化研究(执行主编 李凤日、张怀清、曹林) • 上一篇    下一篇

点云切片结合聚类算法的TLS单木探测方法研究

易静1(), 马开森1,2, 向建平3, 唐杰1, 蒋馥根1, 陈松1, 孙华1,*()   

  1. 1.中南林业科技大学林业遥感信息工程研究中心,林业遥感大数据与生态安全湖南省重点实验室,南方森林资源经营与监测国家林业和草原局重点实验室,湖南 长沙 410004
    2.湖南科技大学地理空间信息技术国家地方联合工程实验室,湖南 湘潭 411201
    3.中南林业科技大学芦头实验林场,湖南 岳阳 414000
  • 收稿日期:2022-06-20 修回日期:2022-08-29 出版日期:2024-07-30 发布日期:2024-08-05
  • 通讯作者: *孙华(sunhua@csuft.edu.cn),教授。
  • 作者简介:

    易静(yijing@csuft.edu.cn)。

  • 基金资助:
    国家自然科学基金面上项目(31971578);湖南省自然科学基金面上项目(2022JJ30078)

Research on TLS single tree detection method based on point cloud slicing combined with clustering algorithm

YI Jing1(), MA Kaisen1,2, XIANG Jianping3, TANG Jie1, JIANG Fugen1, CHEN Song1, SUN Hua1,*()   

  1. 1. Research Center of Forestry Remote Sensing & Information Engineering, Central South University of Forestry and Technology, Key Laboratory of Forestry Remote Sensing Based Big Data & Ecological Security for Hunan Province, Key Laboratory of National Forestry and Grassland Administration on Forest Resources Management and Monitoring in Southern China, Changsha 410004,China
    2. National-Local Joint Engineering Laboratory of Geo-Spatial Information Technology, Hunan University of Science & Technology, Xiangtan 411201, China
    3. Lutou Experimental Forest Farm, Central South University of Forestry and Technology, Yueyang 414000, China
  • Received:2022-06-20 Revised:2022-08-29 Online:2024-07-30 Published:2024-08-05

摘要:

【目的】针对直接使用地面激光雷达生成的冠层高度模型(canopy height model,CHM)和归一化点云(normalized point cloud,NPC)在复杂林分探测中存在单木探测能力不足的问题,研究引入点云切片结合聚类的方法以提高单木探测精度。【方法】以广西壮族自治区6个不同林分密度的人工林样地为研究对象,利用地面激光扫描获取样地的归一化点云数据,提取高度在1.3 m处的点云切片,分别采用基于密度噪声应用空间聚类(DBSCAN)和均值漂移聚类(MS)算法对切片中的树干点云进行聚类。利用野外实测调查数据进行精度验证,并与基于CHM的局部最大值算法和基于NPC的点云分割算法(point cloud segmentation,PCS)的探测结果对比,评价和分析不同探测方法的适用性与参数敏感性。【结果】所有方法均可获得良好的探测结果,各样地的最优总体探测精度得分F≥ 0.86;点云切片结合聚类算法的单木探测方法结果最优。DBSCAN算法的聚类阈值(Eps)和均值漂移算法的聚类半径可显著影响单木探测率,最大Eps取决于最大林木间距,聚类半径接近最大单木胸径时的探测结果最优。【结论】基于点云切片结合聚类算法的单木探测能提高下层林木探测率,可有效改善高密度林分的单木探测精度,为不同林分的单木探测方法选择提供参考。

关键词: 地面激光扫描, 单木探测, 点云切片, 聚类算法, 林木参数提取, 人工林

Abstract:

【Objective】To solve the problem that a canopy height model (CHM) and normalized point cloud (NPC) directly generated by terrestrial laser scanning (TLS) are not capable of detecting individual trees in complex stands, this study introduced the method of point cloud slicing combined with clustering to improve the detection accuracy.【Method】In this study, six sample plots in a plantation with different stand densities in Guangxi Zhuang Autonomous Region, China, were used as the research objects. First, the NPC data of a sample plot obtained by TLS were used to extract point cloud slices at a height of 1.3 m, and then the density-based spatial clustering of applications with noise (DBSCAN) and mean shift algorithms were used to cluster the tree trunk point clouds in the slices. The accuracy was verified by the field survey data, and the detection results were compared with those of the local maximum algorithm based on a CHM, and a point cloud segmentation algorithm based on an NPC. The applicability and parameter sensitivity of the different detection methods were evaluated and analyzed.【Result】Satisfactory detection results were obtained by all methods, and the optimal detection accuracy F-score was ≥ 0.86 for each sample plot. The individual tree detection method using point cloud slicing combined with a clustering algorithm produced better results. The clustering threshold epsilon neighborhood (Eps) value of the DBSCAN algorithm and the clustering radius r of the mean shift algorithm significantly affected the individual tree detection rate, with the maximum Eps depending on the maximum stand spacing and optimum results when r was close to the maximum individual tree diameter at breast height.【Conclusion】Individual tree detection based on point cloud slicing combined with a clustering algorithm can increase the detection rate of understory trees lower forest, effectively improve the accuracy of single tree detection in dense stands, and provide a reference for the selection of single tree detection methods in different forest stands.

Key words: terrestrial laser scanning, single tree detection, point cloud slicing, clustering algorithm, extraction of forest parameters, plantation

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