Improved Alpha-Shapes Segmentation Algorithm For Volume Calculation Of 3D Simulation Tree Branch

With the further implementation of China’s energy conservation and emission reduction policies,higher requirements have been placed on the accuracy of forestry carbon sink measurement,and the accurate calculation of the volume of individual trees has also increased.Aiming at the inaccuracy of the volume model introduced by the insufficient measurement of the trunk and branch bifurcation,resulting in the inaccuracy of the carbon sink measurement results of single trees,this paper proposes to use 3D laser scanning technology to scan and measure standard branch samples,combining improved shapes segmentation algorithm can effectively reduce the volume measurement error of tree branches.The main research contents are as follows:(1)Based on the full investigation of the three-dimensional measurement technology of trees at home and abroad,and the in-depth study and analysis of the three-dimensional laser scanning technology,based on the specificity of the volume calculation of tree branches,a research scheme in this paper was proposed.A laser three-dimensional scanner was used to scan and measure standard branch samples to obtain point cloud data.Then,the Alpha-Shapes algorithm was used to calculate the point cloud edge contours of three-dimensional simulated tree branches and reconstruct them in three dimensions.Segmentation calculation,and finally the volume of each segment is calculated using Alpha-Shapes algorithm and accumulated,so as to measure the volume of the branch model.(2)The standard plastic straight pipe sections,three-way pipe sections and fourway pipe sections of different diameters with precisely known volume values were used to simulate the branching of the branch and verified by experiments with real branches.The detection accuracy and other issues were investigated.The most suitable radius αvalue and the segment height β value were investigated.The volume model error value of the measured sample was obtained by comparing with the standard data.(3)Combined with the measurement data,the uncertainty of the measurement results of the improved Alpha-Shapes segmentation algorithm in the calculation of the volume of the three-dimensional simulated tree branches was calculated and analyzed,and the influence sources of various factors were fully considered.The value of the uncertainty component finally finds that the relative expanded uncertainty is 1.28%(k= 2),which meets the requirements of preset technical indicators.The research of the paper shows that the point cloud data is collected on the branch part through the three-dimensional laser scanning technology and the Alpha-Shapes segmentation improved algorithm is used to calculate the volume.It supplements the shortcomings of tree volume verification,which not only reduces the difficulty of volume verification,but also improves the measurement accuracy appropriately.The research results can be used as the research basis for the further volume calculation of the branch trunk structure.