JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2024, Vol. 48 ›› Issue (4): 113-122.doi: 10.12302/j.issn.1000-2006.202206035

Special Issue: 专题报道Ⅲ:智慧林业之森林可视化研究

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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
  • Contact: SUN Hua E-mail:yijing@csuft.edu.cn;sunhua@csuft.edu.cn

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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