GIS Park

Two-dimensional (2D) vector data is used to indicate the spatial locations precisely, and makes quantitative analysis easily, therefore, the 2D vector data is the main treated object of the spatial analysis of Geographic Information System (GIS); Three-dimensional (3D) terrain data -Digital Elevation Model (DEM) is used to describe the topographical situation. The DEM can be used to extract a variety of terrain parameters, such as slope, aspect and so on, and can analyze the Line Of Sight and Watershed Generation. Therefore, the DEM has an advantage on the qualitative analysis. In order to combine the advantages of 2D vector data and 3D terrain data, the research of the GIS based on the blended data is becoming hot, while the key issue is the data integration and real-time rendering between the 2D vector data and three-dimensional terrain. The above problem is studied in the paper and the following research work is about the issue:1. The topography of 3D visualization technology is researched, and the advantages and disadvantages of different terrain simplification algorithms and the performance of the algorithm are compared. The organization of 3D terrain data, terrain pyramid model and the real-time terrain rendering techniques are studied.2. The methods of the integration of the 2D vector data method and three-dimensional terrain are studied. In the paper, the integration of 2D vector data and 3D terrain is considered from two aspects by analyzing the structure of the vector data and DEM. The method based on geometry, interpolates 2D vector data to the DEM, which can drive up 2D vector data to the terrain surface; the method based on texture, generates the 2D vector into the DEM’s texture in real-time, which is overlaid to the DEM and actualizes the integration of 2D vector data and 3D terrain. The two methods above are also compared in this article. 3. The issues of generating the vector data into texture in real-time, vector texture pyramid model, the correlation of vector texture and the DEM block and the judge of the texture block are studied in the paper. Finally, the method based on texture actualizes integration the vector data and 3D terrain.Finally, based on the above technologies, a prototype system based on the integration of vector data and 3D terrain is designed, and the system based on DirectX is implemented. The performance of the system indicates that the above method can meet the integration of vector data and 3D terrain, while the vector data real-time can render in 3D terrain.