| Interactive visualization of 3D terrain is highly concerned in such fields as GIS, virtual reality and flight simulation. Presently, due to limited hardware capacity as well as the large scope terrain, the real-time modeling and visualization of terrain is still big problem. Based on the software, the multi-resolution representation is a good way for creating of virtual terrain scene and the real-time rendering. Because of this, the multi-resolution representation of terrain has always been the hot topic in such areas as GIS and virtual reality.On the basis of the advantage of the regular structure of grid digital elevation models and also the advantage of the smaller points of TIN on represent terrain, this thesis researches on the adaptive lever-of-detail (LOD) rending algorithms of terrain, with its emphasis on the LOD algorithm based on TIN, including discussion on the LOD algorithm based on quadtree for grid digital elevation models and raising the LOD algorithm based on quadtree for TIN. According to the theory of QuadTIN, Such LOD algorithm based on quadtree for TIN builds a quadtree structure on irregular point sets without additional interpolation points, and combines quadtree based LOD methods and TIN based triangle mesh simplification methods to realize the view-dependence lever-of-detail controlling over the TIN model. By this means, a lever-of-detail mesh, similar with Grid and the TIN hybrid structure, has been acquired.This thesis has provided a new way for the multi-resolution representation of TIN model, having realized the view-dependence lever-of-detail controlling over the TIN model, and making an effective attempt on the LOD representation of TIN by using LOD algorithm based on Grid. At the same time, real-time visualization of the terrain data sets is implemented on PC platform using C++ and OpenGL API. Experimental results show that the efficiency of algorithm in this thesis is high on both computation and memory.
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