Gis-based Visualization Of 3d Terrain Information Display Technology

In a typical terrain 3d scene, the traditional technology program mainly focused on the graphics hardware optimized, that is, through the display lists, vertex buffer object on client sends video server terrain to data packets, but still serious drawing the occupied the storage and bandwidth resources, can't improved fundamentally terrain rendering efficiency.In response to these problems, the paper based on the block in the DEM, using the terrain quad-tree pyramid model to organize the terrain data, were effectively reducing the amount of data when the terrain data was used. Using K-D tree to manage the scene tree can maximize the use of the underlying spatial organization and deal with the problem which was caused to using different terrain data in different precision and different condions. On the basis of K-D tree, visibility culling methods which were effective were used, as the work of the cutting and removing were executived, to achieve the complexity simplified. Improving the traditional core algorithm and scheduling strategy, which were using three levels of management that was progressively displaying from the low resolution of the alternatives (third level) to high-resolution alternatives (second level) to the geometric drawing (first class), can efficiently determine to be visible the visibility of the scene area, while controlling the loading of small data.So the performance of data dispatch system can be greatly improved. In addition, this paper introduces the methods and concepts of texture mapping and texture model can use the idea of Multi-resolution to manage and organize the terrain data.Drawing massive terrain data when the quad-tree and the Pyramid were used to manage texture data had a considerable advantage. On this basis, a Block division method for the rules of object-oriented programming language solved the main drawback in the traditional programs, which was poor performance in the speed of index and extension.We develop a software system based on the key technologies before, which is under the platform of Visual C++ and the database is using file system, OpenGL hardware interface is also used. In order to have more real sense, we put it in a case of outdoor navigation. In the end we also detailed introduce the structure and spatial data organization, and take several data to do the experiments.The system has good efficiency and proved the technology route in our paper. In a word, the methods put forward in our paper could finely solve the problem.