The Implementation And Application Of Automatic Extraction Of Building Contours System Based On Laser Point Cloud

With the development of society and the progress of the city,the concept of digital city has gone deep into the public.In the process of building a digital city,it is unavoidable to establish a 3-D building model.How to complete modeling more realistically and visually requires the efficient and accurate extraction of building outline information.The 3-D laser-scanning measurement technology has become an important means for obtaining building outline information because of its quick acquisition of a large number of point cloud data of buildings.This paper mainly focuses on the extraction of point cloud data from terrestrial laser scanner.Firstly,the related technical foundations of the terrestrial laser scanner and the basic flow of its scanning operations are described.At the same time,the pre-processing of point cloud data is also introduced.And on this basis,using Riegl VZ-400 to complete the data collection required for this paper,and completed the pre-processing of point cloud data,in order to provide data support for follow-up work.Subsequently,study and research of the key technologies of point cloud contour extraction,mainly including point cloud segmentation algorithm,contour extraction algorithm,and contour simplification and regularization algorithm.The point cloud segmentation mainly includes region growing segmentation,Euclidean distance cluster segmentation and segmentation based on RANSAC algorithm;the contour extraction mainly includes convex hull algorithm,Delaunay triangulation,neighbor point geometric feature algorithm and Alpha-Shapes algorithm;contour simplification and regularization is mainly rectangular circumcircle method.For the first two types of algorithms,the basic principle of each algorithm and the pseudocode for programming are given,and using experiments to analyze their advantages and disadvantages.The algorithm for contour simplification and regularization mainly introduces the window regularization process.Finally,using a self-developed terrestrial laser scanner building point cloud contour extraction software to complete a complete set of building contour extraction experiments,and for the extraction results of inner and outer precision analysis and software availability analysis.