Lod Models Of The Complex Geometry In Virtual Reality Research

Virtual reality is a kind of computer interface that simulates man's behaviors in natural environment such as viewing, listening and touching high realistically. Real-time graphics rendering is one of the key techniques for virtual reality. This paper discusses and explores the Level of Detail Model, an efficient graphics rendering-accelerating method.The problems to be solved during the implementation of the LOD model include: the choice measures of the LOD model, the choice algorithm of the LOD model, the smooth transition methods of the LOD model and the automatic generating of the LOD model. The automatic generating of the LOD model is the foundation of all of the others. This paper mainly studies two typical automatic generating algorithms: progressive mesh and view-dependent mesh.The algorithm to generate progressive mesh based on energy optimization needs to establish and solves complicated overall energy optimization equation, so its calculation complexity is very high and the goal of real-time is difficult to achieve. In order to solve the problem, this paper proposes and implements a new progressive mesh simplified method. In this method, edge collapse is also mesh simplification's basic operation, but the cost of edge collapse is measured by the product of the edge square and quadric error metric which is easy to be estimated and can reflect geometric character of the mesh model. The collapsed edge is chosen based on the principle of the least cost of the edge collapse, and the objective vertices generated by edge collapsing are confined to the subset of the original mesh vertices, so geometric information of new vertex needn't to be stored. The experimental results indicate that this algorithm is easy to implement, runs fast and occupy small storage, moreover it can guarantee a high resemblance of the geometric characters between the simplified model and the original model.