基于三维激光扫描技术的单木参数提取精度研究

Extraction Precision of Forest Parameters at Single-tree Level Based on 3D Laser Scanning Technology

利用地面三维激光扫描仪提取单木参数已经成为林业测量领域的研究热点,具有广泛的应用前景。研究旨在探讨地面三维激光扫描系统与传统测树方法得到的单木参数值之间的精度差异。以黑龙江省帽儿山实验林场中的枫桦、落叶松、垂柳、油松、核桃楸和山杨6个树种共20株单木为研究对象,利用激光扫描仪对有代表性的单木进行扫描并利用扫描软件提取相应参数,将其与传统测树方法得到的数值进行对比分析;同时,根据实际测量和点云数据提取的单木参数,使用了4种不同的立木材积计算方法,如立木材积表、望高法(Pressler Method)、中央断面积区分求积法和Delaunay三角剖分算法计算样本木的立木材积。结果表明,与传统测量相比,由点云数据的提取的树高,胸径,和胸高断面积的平均相对误差分别为1.90%、2.02%和1.28%。通过上述方法计算样本木的立木材积的平均值分别为0.466 9、0.409 2、0.469 8、0.464 6m3。与立木材积表的方法相比,望高法、中央断面积区分求积法和Delaunay三角剖分算法相对于立木材积表的相对误差分别为12.36%、0.62%和0.49%。利用三维激光扫描系统测树能够满足精准林业精度测量的要求,同时Delaunay三角剖分算法在计算立木材积具有更高的精度。然而,这种方法在计算严重弯曲树干的立木体积时具有一定的限制性。

The use of terrestrial three-dimensional laser scanning system （3-D LSS） to extract individual tree parameters has become a hot research topic in the field of forestry measurement,which has broad application prospects. The purpose of this paper was to study the precision difference of the measured individ- ual tree parameters from 3-D LSS and traditional measurement. The individual tree parameters of 20 individual trees that belong to six tree species including Betula costata ,Larix grnelinii, Salix babyZonica, Pi- nus tabuliformis ,Juglans mandshurica ,and Populus davidiana in Maoer Mountain Experimental Forest Farm of Heilongjiang Province,China,were measured with terrestrial 3-D LSS and traditional method,and the results were compared. Meanwhile, according to the actually measured tree parameters and the corresponding extracted tree parameters from point cloud data, four different standing tree volume calculation methods such as standing tree volume table,Pressler method, central cross-sectional measurement method, and Delaunay triangular subdivision were used to calculate the standing tree volume of the sample trees.The results showed extracted tree heigh 2. 02‰ ,and 1.28‰ tioned methods wer that compared with the traditional measurement, the average relative errors of the t,diameter at breast height （DBH） ,and basal area from point cloud data were 1. 90‰ ,respectively. The average standing tree volume of the sample trees by the above mene 0. 466 9 ma ,0. 409 2 ma ,0. 469 8 ma,and 0. 464 6 m3,respectively. Compared with the standing tree volume table method,the relative error was 12.36‰ for Pressler method,0.62‰ for central cross-sectional measurement method, and 0.49‰ for Delaunay triangular subdivision, respectively. Using 3-D LSS to measure the tree could meet the precision requirements for precision froestry. Meanwhile, the method of Delaunay triangular subdivision had higher accuracy in calculating the standing tree volume. However,there were still some limitations for this method in acquiring the volume of standing trees with severe crooked trunk.