Research On The Method Of Tree Height Measurement Based On Vehicle-Mounted Dual LIDAR System

As the main body of terrestrial ecosystem,forest plays an irreplaceable role in the global ecosystem balance.With the continuous research,the fields of forestry carbon sink measurement and forest resource information have put forward higher demands on the automated measurement of forest structural parameters.In this paper,in view of the problems of large human interference,low measurement accuracy and expensive equipment in the extraction of structural parameters of forest sample sites,we take the automatic extraction of tree height as an example and propose a method of tree height measurement based on vehicle-mounted dual LIDAR system,which provides a new method for the acquisition of 3D measurement models of forest sample sites and a new way for the automated measurement of forest structural parameters.Firstly,the vehicle-mounted dual LIDAR system is built independently to acquire forest sample data,and the role of dual LIDAR is to collect sample terrain information and acquire tree information respectively.The system has obvious advantages such as flexible and lightweight,simple operation,high reliability,suitable for field operation,good economy,etc.It also has the functions of positioning,navigation and obstacle avoidance.Secondly,the processing method of 3D point cloud data is studied,and a progressive fusion filtering method is proposed for the characteristics of the data collected by the vehicle-mounted dual LIDAR system to achieve the removal of noise points and the separation of tree and ground point data.In order to realize the automation of single wood segmentation and avoid human factors interference,it is proposed to improve the traditional LGC algorithm by using SMA,enhance the connection ability of LGC algorithm to update the internal points and improve the point cloud clustering accuracy,and test the convergence speed and global optimization seeking ability of the improved algorithm by 12 test functions.Finally,the method and steps of tree height extraction based on vehicle-mounted dual LIDAR system are summarized.The validity and accuracy of this method were tested through the tree height extraction experiments in Mongolian oak and ash willow forest experimental sample plots,with the average value of multiple measurements in the field by total station as the true value,and error analysis and regression analysis were conducted to propose a tree height correction model.The method of tree height measurement based on vehicle-mounted dual LIDAR system proposed in this paper has an average relative error of 2.09%～3.07% for direct tree height measurement and 1.71%～1.72% after correction,which effectively improves the accuracy of tree height extraction,while the extraction of tree height in this study is based on obtaining 3D point cloud data of single trees,so it also creates conditions for the full extraction of tree structural parameters.This study provides technical support for the automatic extraction of structural parameters at the single tree level in forest stands.