Database Support for Multi-Resolution Terrain Models

Terrain data of very large scale is widely used in many applications, such as virtual reality, environmental analysis, and GIS. The large size of terrain data makes it very demanding on memory and processing power during visualization and spatial analysis. Multi-resolution techniques have been introduced to address this problem. A Multi-Resolution Terrain Model (MRTM) can provide a large number of simplified approximations (meshes) at various resolution levels together with the original model. For many applications, MRTM can reduce the required data amount by replacing the original terrain model with a mesh at a lower resolution. Such a mesh contains much less data but can be accurate enough according to application requirements. The multi-resolution techniques are applied for both terrain visualization and spatial analysis. However, most existing approaches are based on main memory, i.e., they assume that the entire MRTM can fit in the memory. The fast growing rate of terrain data makes this assumption increasingly impractical. These ix