Numerical Fitting Of Three-dimensional Terrain

With the development of computer technology, remote sensing, geophysics and related technologies, geological information system (GIS) has been implemented in the various walks of life. As we know, we live in a three-dimension space. But the current GIS is based on dual-dimension spatial information, which has much limitation. It shows three-dimension object through a dual-dimension way, so it is inevitable that a lot of spatial information can not be made use. In the research area of geological science, all the research objects are three-dimension and it is very hard to get an accurate phenomenon of geological objects in our mind. So if geological objects are visualized, it is possible for us to not only show clearly characteristics of various geological objects and their spatial combination rules but to make geologists visualize geometry conformation, correlation and distribution of geological phenomena and find problems accurately and analyze them. This urges us to do a research on three-dimension geology information visualization. Three-dimension geological information visualization is concerning with many subjects including GIS, geological information visualization, computer graphics, three-dimension expression technology, database, virtual reality and so on. The visualization of geological objects has its own particularity such as difficulties in sampling of three-dimension geological data, high cost of sampling and sparse sampling data, which can not describe the real situation of geological objects accurately. This needs us to compute sampling data scientifically in order to get more approximate data. First of all, this thesis analyzes the significance, the current state, applied prospects and the current difficulties of geological information visualization. Then the theoretical bases of geological information visualization and three-dimension data function are introduced. In addition, double three sampling in dual-dimension is extended into three-dimension and get trinary three spline function based on regular data. Furthermore, the computing method of product calculation is used to compute trinary three spline function, which can be used to switch ternariness to unitariness. This thesis also analyzes the current three-dimension visualization software including OpenGL, VRML, Java 3D and the feasibility of using OpenGL as three-dimension geological information visualization software. Then the basic principles and methods of OpenGL are described and the implementation method of OpenGL in three-dimension geological information visualization is presented. Finally, in the thesis an instance in geological field is developed through the method of object-oriented analysis and design and the trinary three spline is implemented in it. The instance is a three-tier structure application and the data communication among the modules is solved through STL. So the application has strong maintainability and extensibility. All in all, this thesis is possible to provide some reference for further research in this field.