Research On Real Time Terrain Visualization Algorithm Based On Grid/TIN Hybrid Structure

3D terrain visualization comes under increasing scrutiny as the important content of geographic information system. In the traditional 3D terrain, people often use Grid as the basic data for representation of terrain information, however, the limitation of data structure leads to the terrain feature details expression efficiency is not high. Considering the characteristic of TIN in this paper, by combining their respective characteristics, this paper use Grid/TIN hybrid data structure to express terrain information. 3D terrain data is usually large, limited by computer performance, the terrain can’t be loaded and rend by once, so the terrain need be simplifyed on the basis of the quality of the graphics. Traditional simplification algorithm o based on Grid or TIN alone does not deal with hybrid data very well, in order to solve these problems, this paper does the research in the aspect of Grid and TIN hybrid structure, real-time dynamic simplification and the organization and scheduling of hybrid data.The following aspects are studied in this paper:(1) Data organization of Grid/TIN and the construction of TINA data fusion rule of Grid/TIN and a organizational hybrid structures of Grid/TIN are designed, and the terrain tiles as the basic division of terrain data are used, a detailed implementation method of constructing TIN based constrained vector line is put forward.(2) The Grid/TIN hybrid data real-time simplified algorithmAiming at the shortcomings of traditional classic ROAM algorithm and PM algorithm in dealing with the question of hybrid data: the simplification error of ROAM, visual vertebral clipping and render method is improved. The method of PM collapsing cost calculation, the processing of topological error in real-time rendering is analyzed and improved, and put forward a crack elimination algorithm between Grid and TIN, TIN and TIN. In order to further improve the rendering efficiency, frustum culling and rendering aiming at the whole scene are optimized.(3) The organization and scheduling of terrain hybrid dataAiming at the large amount of terrion data and the limition of computer memory, a method of block Grid/TIN hybrid data storage based on file system is designed, and proposes a data buffer scheduling strategy based on multi thread, and the effectiveness of the strategy is verified by experiment.Based on existing Grid and TIN classic simplification algorithm, this paper put forward a real-time dynamic simplification algorithms, which is suitable for Grid/TIN hybrid data structure and a data scheduling algorithm based on multi-thread and multibuffer.Through experimental verification of the corresponding analysis verifies that the algorithm can effectively improve real-time rendering efficiency of the hybrid data terrain scene, realize the terrion roaming real-timely,achieve the goal of this paper.