Research Of Mesh Model Simplification And Visualization For Large-scale Terrain

The three-dimension visualization technology of large-scale terrain is now a hot research topic widely concerned by people, which has been applied to three-dimension GIS (Geographic Information System), military simulation, VR(Virtual Reality), and many other fields. As one of the most important research area in three-dimension visualization technology, terrain mesh simplification algorithm is an effective method to solve the contradiction between huge amount of data set and limited storage of computer. It can also decrease the quantity of data used for describing terrain to the maximum extend and reduce the complexity of terrain modeling on the premise of ensuring terrain accuracy. Hence, this task possesses important significance in the three-dimension visualization technology.The huge data quantity of large-scale terrain limits the development of rendering algorithm. Otherwise, the rate and quality of terrain rendering depend on how to effectively organize the terrain data and simplify terrain mesh model. Aiming at solving the problem mentioned above, this paper discusses how to realize visualization technology of large-scale terrain. Besides visualization technology and mesh model simplification method are introduced, two terrain mesh models, RSG(Regular Square Grid) and TIN(Triangulated Irregular Network), are also compared. In order to resolve the huge data quality of large-scale terrain, we apply the technologies of culling simplified view frustum, terrain partition and multithreading to organize and real-time dynamic schedule the large-scale terrain data. The bintree and quadtree data structure are discussed for regular mesh model simplicfication. Cracks caused by inconsistent resolution of neighbor nodes in the quadtree structure are eliminated by importing Y model primitive for constructing continuously mesh. TIN model simplification algorithm of terrain is discussed. By the method of searching neighbor vertices to improve vertex split operation of progressive mesh algorithm and the strategy of processing the boundary topological relation of TIN model blocks, we can effectively renew topology of vertices and ensure mesh of each partitioned terrain continuous.