三维激光扫描数据的单木树冠体积精确计算

Accurate calculation of single-tree crown volume based on 3D laser scanning data

针对现存单木树冠体积计算方法不能剔除树冠外部较大空隙以及树冠边界提取粗糙的问题,该文在对生长算法改进的基础上,提出了基于过滤三角网的树冠边界精确提取算法,确定了树冠最优分层间距与过滤阈值,实现了树冠体积的准确计算。该方法在对扫描的单木树冠点云数据进行拼接和过滤后,进行等间隔分层处理获取其切片点云,然后采用过滤三角网算法生成符合树冠实际情况的边界,再通过计算的切片面积获取各层点云间的体积,最终累加各层点云体积得到树冠体积的精确值。对校内树冠三维激光扫描实测数据进行计算与分析,结果表明过滤三角网算法提取的树冠边界能顾及树冠外部存在的空隙现象,进而得到准确的树冠体积值;此外,过滤三角网算法对树冠点云数据的密度要求远低于体元法,具有较高的算法稳定性。

The existing volume calculation method of the single-tree crown cannot eliminate the large gap inside the crown and the extraction of the crown boundary is rough.On the basis of the improvement of the growth algorithm,an accurate algorithm to extracting the crown boundary based on the filtered triangulation was proposed,and the optimal stratification spacing and filtering threshold of the canopy were determined,which realized the accurate calculation of the crown volume.Firstly,through splicing and filtering the scanned single-tree crown point clouds data,slice point clouds were obtained by stratification at equal intervals.Then the filtering triangulation algorithm was used to generate a boundary that in accordance with the actual situation of the crown,then the volume between each layer of point clouds were obtained through the calculated slice area.Finally,the point cloud volume of each layer was accumulated to obtain the accurate value of the crown volume.The calculation and analysis on the measured data of laser 3 D laser scanning of single-tree crown in the campus showed that the crown boundary extracted by the filtering triangulation algorithm could take into account the gap phenomenon inside and outside the crown,and then obtain the accurate crown volume value.In addition,the filtering triangulation algorithm had much lower density requirements for canopy point clouds data than the voxel method and higher algorithm stability.