基于地面激光雷达点云的树木冠层变化定量分析

采用切片形式的Alpha Shape 3D法估算树木冠层体积,从不同相对位置分析体素空间分布状态的变化.基于网格模型提取变化点云,研究冠层组分的空间变化,以受台风玛利亚破坏树木冠层为例,应用所提出的方法进行定量分析.通过多角度分析可知,该台风对目标树木总体破坏较小,树木冠层垂直方向的中下部受损较大,枝叶受损多集中于距离冠层中心水平方向2.0～2.5 m区间.分析结果表明,该定量分析方法可以反映树木冠层分布及体积变化情况.

Quantitative analysis of individual tree canopy changes based on terrestrial lidar data

The canopy structure of trees greatly affects its ecological function and landscape effect, and its changes directly or indirectly reflect the influence of changes in tree growth environment and natural disasters. We present a quantitative analysis scheme for canopy changes using high-precision terrestrial lidar data. The proposed method uses the sliced Alpha Shape 3D form to estimate the canopy volume; the canopy point cloud is voxelized to investigate the changes in canopy spatial distribution. The canopy loss or growth point cloud is extracted by reconstructing the canopy mesh model and calculating the distance between the point cloud and the mesh model. Taking the trees affected by the typhoon as an example, we found that after the typhoon, the middle and lower parts of the canopy were damaged more severely, the damage of branches and leaves in canopy is mostly concentrated in the outward layers 2 to 2.5 m from the main trunk. The analysis results show that the quantitative analysis method can quantify the canopy distribution and volume changes of the tree canopy.