The Research On Photorealistic Rendering Technology For Three-dimensional Terrain Based On GPU

In recent years, Geographic Information System,GIS is using widely in our daily life.Photorealistic Rendering Technology for Three-dimensional Terrain as a core technologydevelop rapidly, and it has become the hot spots of Geoscience, Geomantic, ComputerGraphics and other scientific research. Photorealistic Rendering Technology forThree-dimensional Terrain has been apply to many relevance theories in different areas, suchas, Computer Graphics, Digital Image Processing, Computer Geometry and SpatialInformation, which integrated with data acquisition, Three-dimension Terrain Model, meshsimplification, mass data processing and landscape simulation technology. PhotorealisticRendering Technology for Three-dimensional Terrain has been extensively studied, because itis not only demanding higher accuracy, but also needs to satisfy the request of real time ofmass data processing.Aim at the data multiresolution dynamic loading and the draw accuracy problems inphotorealistic rendering of three-dimensional terrain, The method of gain3D terrain data, avisual modeling method and Levels of Detail, are introduced in the first place in this thesis,and it locked at visible theory, eliminating algorithm of render in scene, the call mechanismbetween cache and internal and external storage, and3D topography optimization techniques.Then quad tree structure is introduced in detail and compared with binary tree structure. Atlast, the thesis compared with two kinds of Levels of Detail, which is indicated the continuousLOD model of quad tree based segmentation and the adaptive dynamic multiresolution LODmodel.This thesis represent3D realistic terrain by DEM, and setup LOD model based onregular network. This thesis adopt the mechanism of adaptive LOD dispatcher using bufferedinput, and through secondary quad tree to improve search speed, in order to achieve3Dvisualization as well as reduce overhead costs. The achievement of reduce CPU cost issucceed in using GPU vertex shader to extract DMA DTED by using CUDA ProgrammingTechnology. The improvement of visual effect of terrain rendering is achieved in usingrestricted relationship between levels and skirt method to eliminate the crack in3D terrainmodeling process. This thesis use the method of evaluating nodes to judge partition innetwork in the level of detail, and it also improve the efficiency and enhance the effect of3Drealistic terrain.Based on VC++and OpenGL, design and implementation of a three-dimensional terrai- n and photorealistic rendering systems, in order to satisfy the requirements, such as,three-dimensional terrain roaming, multi-angle view mobile rotation, mesh simplificationreal-time display and so on. For the terrain texture mapping, the author compared the originaltexture with color of three-dimensional terrain, in order to achieve the render of the texture inthree-dimensional terrain.In a word, this thesis use secondary quad tree data index and GPU acceleration techniqueto accelerate the system of visualization of3D terrain. At end of the thesis, the author use themethod of evaluating nodes, elimination of the crack, the mechanism of adaptive LODdispatcher using buffered input to present the3D realistic terrain with a higher quality ofdrawing as well as real-time requirements.