Research On Extraction Of Single Tree Canopy Structure Factor With Terrestrial LiDAR

With the increasing global climate change,the research on the forest ecological function,material cycle and energy flow has attracted the attention of scholars both at home and abroad.The single tree is a tree canopy photosynthesis,respiration,transpiration of main places and other important physiological activities,but also trees occur concentrated area of material circulation and energy flow,study the structure factor of single tree canopy is very important for studying the physiological and ecological function of trees.The existing measurement methods and instruments have low accuracy,large workload,small scope of application,low efficiency and so on.Therefore,it is urgent to find a method which can efficiently and accurately extract the structure factor of a variety of single trees.Ground laser radar has high scanning accuracy,strong penetration,can restore the true features of characteristics of three-dimensional objects,in which the traditional canopy research method and instrument incomparable advantages,based on Ground Lidar extraction of tree canopy structure factor has become a new research means.In this paper,the following aspeets:(1)using the FARO Photon Type 120 ground-based laser radar,we selected the 6 individual trees to carry on the three dimensional laser scanning,and obtained the single tree point cloud data.(2)further registration of point cloud data splicing,noise removal,segmentation processing,the point cloud data of single tree canopy,the combination of various methods of individual tree crown width,crown height,crown volume,crown surface area,leaf canopy porosity,vertical distribution of canopy structure factors were extracted,and the extraction results were compared to verify the accuracy and.The conclusions of this study are:(1)it is feasible and effective to extract the single wood canopy structure factor from the ground based lidar,which has obvious advantages compared with the traditional instruments and measurement methods.The use of ground-based lidar for a scan,the obtained point cloud data can be used to extract a variety of canopy structure factor,to reduce the workload of the industry measurement,efficiency has been greatly improved.(2)the algorithm of extracting the structural parameters by the ground-based lidar is advanced.The three-dimensional coordinates of point cloud data is accurate,can effectively decrease error generated for observation.In the extraction of crown volume and surface area,using the method of irregular geometry projection surface is better than the previous simulation accuracy is improved;the use of point cloud element algorithm,can effectively eliminate the gaps in the canopy of the simulation of the crown part,more precise,more accurate.For the vertical distribution of the blade,the ground-based lidar solves the problem of the observation of the canopy gap and the intermal blade.(3)using the point cloud data to extract the canopy structure factor has the accuracy and reliability.After inspection,the total station measurement error between crown crown height and the point cloud data to extract the value at 10%.