Shape Analysis Of 3D Discrete Point Set

The 3D discrete point set is a discrete sampling of the surface geometry of a three-dimensional object.The main research goal of this subject is to deduce the surface geometry of the object from the 3D discrete point set and to calculate the shape characteristics of the object.In the process of realizing this goal,we have made some progress in 3 aspects:(1)the initial analysis of the shape of the point set is carried out by solving the minimum bounding ball of the 3D discrete point set;(2)for the non uniform 3D discrete point set,a fast and accurate 3D object surface reconstruction algorithm with variable alpha is designed by improving the traditional alpha-shape surface reconstruction algorithm;(3)for the large-scale point cloud data,a 3D surface reconstruction algorithm based on preserving local extreme points is proposed,and the algorithm is applied to the crown analysis in forestry measurement.Our contribution lies in the algorithm design.In theoretical innovation,a surface reconstruction algorithm with variable a is proposed for non uniform sampling point set.A surface reconstruction algorithm with local extreme points is proposed for large-scale point cloud data,which can effectively improve the effectiveness and efficiency of the reconstruction.The application of the innovation is to apply the algorithm to the calculation of canopy volume in forestry inventory.Compared to the traditional geometric method which abstracts the crown into a single rule and calculates the crown volume with slice method and the fixed step length,the new algorithm is more accurate.