Distance-weighted Quadric Error Metric Simplification Algorithm Based On Triangle Collapse

As the rapid development of science and technology, more and more precise and complex object models can be constructed in many computer graphics systems such as computer graphics, virtual reality, geographic information system and medical image system. Triangle mesh model is widely used to represent those objects and for some mesh model it usually contains thousands of triangles. It overwhelms the processing performance of current graphics systems to store, transmit, and render this large-scale data of these models. And such complex models are not always required because in many cases there isn't any need to use such precise mesh model. For example in VR environment the refine meshes is only used when the object is very important or it is very near to the view point. Thus it becomes an important focus question how to render object model rapidly and keep better display quality. Mesh simplification becomes to be more advanced and popular technology. It provides approximate models of complex models by reducing triangles, edges and vertices and the simpler models keep the basic geometrical shape of the originals.Firstly this dissertation gives an introduction on the background knowledge of mesh simplification and goes deep into investigation with the character of current representative algorithm. After analyzing the shortcomings and strongpoint on some algorithms about mesh simplification algorithm from home and abroad, a discussion on key technology of simplification is presented, such as the selection of simplification method and the error evaluating methods,after introducing the above basic knowledge we illustrate the definition of the LOD model.Finally this thesis is dedicated to the simplification method for triangle mesh models and a high efficiency method with quadric error metric triangle collapse on simplifying triangle mesh models is implemented and a few mesh models are simplified using this system to prove the validity of the new algorithm. In this algorithm it introduces distance-weighted quadric error metric approach and the control weight of triangle's shape into multiresolution mesh representation. Thus the desired mesh model related to the viewpoint is produced with the introduction of distance-weighted quadric error metric. Besides, the quality of newly created triangles is also improved by the control of the weight of triangle's shape. At the same time, for avoiding oversimplifying on some part of the model and the appearance of some too large triangles, we have also adopted the neighbor-freezing method. Experiments show that this algorithm is stable and efficient and the quality of the simplified triangle's shape is relatively perfect. Compared with Garland algorithm, the algorithm speeds up the model simplification procedure and improves the quality of model simplification.