基于TLS的红松树冠半径提取及其外轮廓模型构建

【目的】探究基于地基激光雷达(Terrestrial Laser Scanning, TLS)点云数据提取人工林中红松不同树冠深度处最大树冠半径(crown radius,R_C)的精度，建立基于TLS点云数据的树冠外轮廓模型，为基于TLS点云数据研究树冠结构奠定实践基础。【方法】以30株人工林红松解析木的TLS的点云数据以及实测枝条因子为数据源，采用点云分层投影法提取不同树冠深度处的最大树冠半径，并与根据30株解析木各轮最大枝条计算出的半径对比进行精度分析。最后，基于TLS所提取的树冠半径进行红松树冠外轮廓模型的构建。【结果】最大树冠半径总提取精度为86.17%,不同树冠深度处提取精度存在差异，提取效果最好的相对冠深范围为0.15～1.00,精度均在90%左右；提取效果最差的相对冠深范围为0～0.15,精度为60.27%～75.79%。3种常用的树冠外轮廓模型(单分子式、二次抛物线、3参数Weibull方程)均具有较好的拟合效果。3参数Weibull方程为最优模型，对最优模型再参数化后引入的变量为胸径(DBH)和高径比(HD),拟合效果明显提高。【结论】基于TLS...

Extraction of crown radius and development of crown profile model of Pinus koraiensis based on TLS

【Objective】 The aim of this research was to explore the accuracy of extracting the maximum crown radius (CR, R_C) at different crown depths of Pinus koraiensis based on Terrestrial Laser Scanning (TLS) point cloud data and developing a crown profile model based on TLS point cloud data. This study provides a practical basis for researching tree crown structures based on the TLS point cloud data. 【Method】 The TLS point cloud data and the branch factor data measured were from 30 analytic Pinus koraiensis. The CR at different heights was extracted by layered projection of the point cloud data and then compared with field-measured data of 30 analytic P. koraiensis trees for precision analysis. Finally, the R_C extracted from the point cloud data was used to develop a crown profile model of P. koraiensis. 【Result】The total extraction accuracy of the maximum R_C was 86.17%. There were differences in the accuracy of radius extraction for different crown depths. The range of relative crown depths with the best extraction effect was 0.15-1.00, and the accuracy of R_C extraction within this range was approximately 90%. The range of relative crown depth with the worst extraction effect was 0-0.15, and the extraction accuracy within this range was 60.27%-75.79%. The three selected equations (mischerlich equation, quadratic parabolic equation, 3-parameter Weibull function) had good fitting effects and the 3-parameter Weibull function was the optimal model. We re-parameterized the optimal model and added DBH and ratio of height to diameter (HD) to the model, and the goodness-of-fit of the model was significantly improved. 【Conclusion】 Based on the TLS point cloud data, the accuracy of the maximum R_C extraction using the point cloud layered projection method satisfies the requirements of model development. Therefore, TLS data can be used to approximately replace field-measured data in crown profile model research.