Integrated Dynamic Model for Multi-resolution Data in Three-dimensional Gis

With the development of digital earth and cyber city, there is an increasing equipment on management and vitalization of integrated 3D model data and image data. How to improve the speed and visualization effect of three-dimesional (3D) model is a major research issue in 3D GIS. In order to improve the speed of 3D visualization, such as flying/walking through, many algorithms have been developed to reduce the data volume of 3D model, for instance, Level_of_Detail (Lod) algorithm. However, image data is also another important factor effecting the operation speed and reality of 3D model. Image data as the texture of surface of 3D model can enhance the reality of 3D model. For the reason that different graphic cards may have different restriction in the size of texture, the texture has to be managed very carefully. This paper proposes a new method to manage image data when a image is used as the texture for a 3D GIS environment. First, the data structure of multi-resolution texture model, which is developed to manage the large texture, is presented. Secondly, the algorithm that creates the multi-resolution texture model is developed, which is of vital importance for the texture mapping. Thirdly, the method of determining a proper texture resolution to map texture on the surface of 3D model based on viewer conditions is discussed. Finally, several experiments are illustrated.