The Technique Of Large Scale Terrain Walkthrough Research Based On LOD

Recently, terrain walkthrough has been widely used in computer games, VR, flight simulations, military mission planning and GIS etc. With the applications of 3D visualization and development of computer techniques, more demands are rise.In GIS, terrain visualization helps to understand the interrelation of spatial data and the result of the analysis. Terrain visualization is an important part of 3DGIS and a major technology to establish Digital Earth.As the development of massive data acquirement and production, the common memory based terrain visualization cannot fulfill the requirement and large scale terrain walkthrough has now become an important field of virtual reality and 3D GIS. Due to limited hardware capacity and the large volume of terrain data, most of existing virtual reality system and 3D rendering software does not support real-time changing and updating of the terrain data on-the-fly at current. The building of large scope of virtual terrain scene with high image fidelity needs researching on system hierarchy, scene simplification, data paging, and image fidelity etc. Resulting virtual terrain scene should make user easy understood what they faced and get what they want.In this paper, the technique of store and paging of massive data is presented. The software system adopts the management based on spatial data engineering and blocked data. A multi-resolution simplification model is also presented with structure of binary triangle tree. It is sometime similar to ROAM but easy to be implemented. At last several error metrics are designed and analyzed. At last, a system of large scale of terrain walkthrough is implemented and it runs well.