Study On The Method Of 3D Surficial Geology Modeling Based On AutoCAD Graphics

With the development of computer technology and information industry, 3D geological model plays more and more important role in the field of engineering design. 3D terrain modeling is one of important module in the system of 3D geological modeling and the speed of algorithms for terrain modeling has direct effect on running efficiency of the whole system. What is emphatically studied in this thesis is the algorithm for fitting large-scale scattered data of terrain. In addition, an effective method to find each 2D geological block is studied. And terrain is combined with geological borderlines, which form the 3D surficial geology model. Summarily, the main contents of this thesis are embodied as following:To meet the need of acquiring the terrain data, two methods are discussed for data extraction from AutoCAD graphics and the basic approach with ObjectARX program is given. It is a fast and effective way to get large-scale data needed in 3D terrain modeling.The fundamental theory and methods of digital terrain modeling including Triangulated Irregular Network (TIN) and Regular Square Grid (RSG) are studied. And the basic approach of constrained Delaunay triangulation is introduced. What is emphatically studied in this thesis is the algorithm of hierarchical B-Spline. This algorithm for fitting large-scale scattered data is fast and makes surface with C~2-continuity and small error. It can effectively solve the problem of surface fitting of the terrain model.An effective method to find each 2D geological block according to geological borderlines is studied. To use this method can express the information of geological block and make the 3D surficial geology model which is more visual and intuitionistic than the pure 3D terrain model. At the same time, this is also the foundation of 3D geological modeling.At last, we accomplish the visualization of 3D surficial geology model with OpenGL.