Research And Application Of 3D Terrain Visualization Based On OpenGL

3D visualization is an important direction of research in the field of computer graphics. Many researchers have been carrying out a lot of fruitful research, and many mature technologies have been used in games, films, animation, industrial design and other fields, but the technologies are only used occasionally in GIS. Terrain 3D visualization technology is an important research content of three-dimensional Geography Information System, making geographical information more intuitive, vividly demonstrated in front of people. Under the background of "Digital Earth", it will have wide development and application. Therefore, it is of great significance to study how to establish realistic 3D visualization of the topography.This thesis adopts the standard technology of 3D graphics, OpenGL technology to realize different models of the terrain 3D visualization based on Windows XP system and Visual C++ 6.0.The main work is shown as follows:(1) Introduce the basic concept of OpenGL and its work principle, with the emphasis on the OpenGL technology such as 3D graphics transformation, visible area determination, illumination model and texture mapping, etc.;(2) Summarize the methods of Terrain 3D Visualization model building, including Digital Terrain Model,Fractal Dimension, Data fitting model, etc. ; recommend Digital Terrain Model and introduce the merit and demerits of different building method in detail;(3) Build the basic framework of OpenGL software in Visual C++ language environment, through a series of steps including the settings of OpenGL Basis, Pixel Format, Rendering Context and Device Contextand OpenGL style settings;(4) Sum up gridding method of discrete data such as Inverse Distance Weighted, Kriging, Neighbor and SPLINE, and their applicable situation, focusing on Inverse Distance Weight of mathematical models and the flow chart of its calculation;(5) On the basis of the theories and results mentioned above, achieves the different color, texture mapping, velarium of different models display of 3D Terrain Visualization based on OpenGL technology, adopting the method of grid DEM model and Inverse Distance Weighted method to conduct the gridding of discrete data. Based on in-depth study of advanced OpenGL texturing, realize the simulation of Contour Line, Earthwork Engineering, Vegetation, using texture coordinates generated, multi-texture, texture binding, other related technologies, and expand the simulation of Simple Stratified Stratum Geology.Finally the author makes a conclusion of the whole thesis and some problems worthy for further studies are put forward.