Research On The Generation Of CSG Model Based On The Grid Point-Cloud

With the development of society, the people’s culture level have improvedgradually, so people demand for more and more3D spatial information. To meetpeople’s needs, the technology of surveying and mapping developed from2D to3D,from plane into space. The paper-maps gradually from the historical stage,3Delectronic map bring the big help and more information to people. In expressingthree-dimensional space three-dimensional model has great advantages, it canexpress3D information visually, has rich three-dimensional information, so thatpeople has great interest in building it, as well as variety of3D model appear in theworld. In recent years,3D laser scanning technology developed rapidly, it is usedto acquire basic data for every kind of3D model because of its fast, accurate accessto real-world three-dimensional information, instance point cloud model,triangulation model.Different three-dimensional model to describe the different entities has itsown advantages, for the fine model triangulation model is good at showing thedetails of the model, if the details are not require, point cloud model is enough. Forthe rule objects, CSG is a better method to express them than point cloud modeland triangulation model because their small data, easy to operate and without lossof accuracy. If we have high precision basic data, we can build a high precisionCSG. In this paper, I will introduce a method that build a CSG use the basic datathat is grid point cloud which acquired by the3D laser scanner.When extract feature points of the spherical cloud this article describes anautomatic new method. The extraction of planar features in the point cloud authorspropose a combination of improved RANSCA seed point expansion algorithm, andimplemented based on prior academic research consistency algorithm method to extract the plane algorithms. After extracting the feature point cloud with twosmall squares fitted sphere and cylinder, to get the parameters for the voxel of thetriangle overtaken after preparation. When building a cube in a paper designed toextract the coordinates of the corner cube eight ways, and get better results. Finally,according to the construction method of triangulation which is designed in thispaper and polyhedron previous studies, author obtained by CSG Boolean operation.In the last article, the author briefly describes the algorithm for the validationand implementation of CSG models generated in Visual Studio2005developmentplatform using C#language with C++language and OpenGL programmingtechniques and developed a validation system.