Research On LOD Model Simplification And Real-time Rendering Of Large-scale Terrain

Visualization of large-scale terrain is highly concerned in such fields as geographic information systems,virtual reality,disaster simulation and battlefield environment simulation.With the rapid development of the remote sense,satellite technology and computer technology,people is expecting to investigate or view larger terrain regions with finer precision,which put forward higher requirements for real-time rendering of terrain.However,generation of large-scale model of terrain and real-time display are still major problems,given the capacity of today's computer hardware.In this dissertation,issues of generation of multi-resolution terrain models and real-time rendering are studied systematically,and the main contents are listed as follows:1).The proposition of a parallel model simplification algorithm for preprocessing of large-scale terrain model.Level of Detail(LOD) as a real-time terrain rendering method has been commonly used,and the key is to generate different resolution model by using model simplification algorithms.Parallel processing is a viable approach to solve this problem.A quadric error metrics based parallel model simplification algorithm has been proposed taking quad-tree as subdivision scheme.Based on tests running on a cluster system, the efficiency of model simplification is shown greatly increased.2).For real-time rendering of large-scale terrain,a specified local coordinate system is selected as the reference coordinate system of real-time rendering of large-scale terrain;an viewpoint control algorithm which take into account the curvature of the earth and a view-dependent LOD model selection algorithm are proposed;a visibility culling algorithm which is applied to terrain rendering is presented to improve the efficiency of real-time rendering by reduce the number of polygons drawn.3).A large-scale terrain visualization prototype system is designed and implemented with the modules of model pre-processing and real-time rendering, and some tests and application example are also given.