Research On Technology Of Level Of Detail Model Simplification

Virtual Reality,Computer Simulation have been widely used in many fieldsAlong with the development of Virtual Reality application, people increasing demand complexity and third dimension of Virtual Environment.These applications need not only realism complex Virtual Environment,but also require the user can interact with the virtual scene in the real-time.But along with the improving of complexity of virtual scene, it need more graphics datum to render. Yet some datum sizes are more larger than what the computer graphics hardware can display in real-time. For solving the conflict between complexity of virtual scene and interaction in real-time, researchers have gained some research results .The level of detail algorithm became more advanced and popular technology.At first , paper present background knowledge of computer graphics, for example:virtual reality, realistic graphics real-time rendering,OpenGL technology,graphics transform and so on.Then paper present the origin , developmental trend and sort of level of detail algorithm.Paper research LOD algorithm and separate geometry model algorithm from terrain model algorithm.After analyzed and studied on some algorithms about geometry model simplification algorithm from home and abroad, at chapter 3 of paper present some mesh simplification algorithms ,including mesh simplification algorithm based on vertex-clustering, mesh simplification algorithm based on decimation, mesh simplification algorithm based on collapse, continuous multiresolution mesh simplification algorithm and so on.Then we combine edge collapse algorithm and progressive mesh realism multiresolution LOD geometry model simplification algorithm. This algorithm realizes a kind of triangular mesh simplification algorithm based on half edge collapse. It covers not only triangle normals around vertex but also other geometrical characteristic.such as triangle area to calculate cost of collapse, which efficiently simplify mesh models. Andthe paper utilizes progressive meshs store mesh information and generate continuous level of detail (LOD) models. They support multiresolution representation, arbitrary refinement etc. Finally, paper provides application example and analytic data.At chapter 4, we focus on our research on the rendering, roam and continuous multiresolution terrain simplification algorithm of large-scale terrain scene.At first we present basic conception and classical algorithm of continuous multiresolution terrain simplification, for instance,vertex error estimated and quadtree terrain algorithm.Then we realizes continuous multiresolution terrain simplification algorithm base on Bounding Sphere Hierarchy and Longest Edge Bisection,it recursively subdivide a triangle mesh defined over regularly grid, at the same time compute projected error of vertex by the bounding sphere.So a vertex's projected error must always be smaller than any of its ancestors, then its ancestors have been actived earlier and cracks eliminated.