Study On Constructing DEM And 3D Visualization In Typical Karst Mountainous Area

With the development of GIS technology and computer graphics, 3D visualization is the hotspot of current internal and abroad. DEM, which is an important part of GIS, is a basic data for terrain display and analysis. In this paper, taking the typical karst Fragmentized Bijie Mountainous Area as an example, some methods of creating DEM and interpolating computation are summarized and studied. After scanning original topographical maps, vectoring, and taking consideration of adding topographical characteristic lines, such as single point, rupture line, boundary line, formation line contained, high resolution Triangulated Irregular Network (TIN) is attained which can be converted to grid DEM. After having been compared elevations of 100 points derived from DEM with original point's elevations of the topographical map, and calculating the mid-error and the mean error, the quality of DEM is approved reliable.Digital terrain analysis is a frame that integrates terrain data into terrain analysis. The main idea includes: the computation of basic terrain factor, the abstraction of terrain characteristics, the analysis of visualization, etc. This paper computed and abstracted the basic terrain factor such as slope, aspect of study area to analyze. The research on 3D visualization and spatial analysis is very important.Based on lots of advanced results of computer graphics, computer science, GIS and topography, etc. this paper discussed the related theory, techniques and arithmetic of three-dimensional terrain visualization implementation based on OpenGL. At last, based windows XP system on the researched result and Visual C++ 6.0, the paper use DEM and remote sensing images and OpenGL program techniques to construct a system for real time display and ramble of three-dimensional terrain visualization in BiJie demonstrating area. The system can realize different pattern three-dimensional visualization of line, different color and texture, etc. and has the functions of real time dynamical browse, three-dimensional coordinates query, grid data and three-dimensional figure export etc.