Trees Parameters Extraction Study From Terrestrial Laser Scanning Data

Terrestrial laser scanning Technology has been prosperously used in forestry parameters measurement.It provides a new way for tree parameters extraction and simplifies the complex field work.However,extracting tree-measuring factors from terrestrial laser scanning data increases a lot of interior mapping work.There is no convenient methodof automaticlly extracting parameters.Aiming at the shortcomings of tree parameter extraction and visualization,this paper introduces and compares different skeletonization methods,then chooses suitable skeletonization methodfor topological structure and parameters extraction and completes visualization simulation system for terrestrial laser scanning data visualization.Firstly,skeleton generation algorithm of 3-D point cloudhas been classified according to the different structural segmentation process,respectively,the clsustering method,the level set extraction algorithm,graph method,laplacian method.This paper compares four methods in two aspects of descriptive and algorithms demands on centricity,connectivity,homotopy,grade,the algorithms robustness characteristic,summarizing the advantages and disadvantages of those methods.Then,SkelTre has been selected from the graph methods to generate skeleton model and improved toobtain clear tree branch structure.Secondly,skeleton model is composed of spatial straight line labelled by direction marker of each node.With custom branch evalution standard to extract tree structure and identify the correct branching structure,tree measurement factors such as diameter at breast height,branch length and angle are extracted by morphological method.The measurement factors of sample wood and the estimated parameters of skeleton model resultsshows that skeletonization extraction scheme in forestry parameters' extraction presents an applicable value for forestry investigation.Finally,this paper develops the trees' visualization system based on terrestrial laser scanning data on integrated development environment visual studio,computer language C#.The software system implements skeleton algorithm and TLS data visualization,designs topological modification module and indentifies branch structure by graph depth first algorithm and custom branch conditions.Establishing tree factors extraction and visualization system better realize extracting branch structure and parameters.