Research of 3D Representation Theory and Technology of Geographic Information

Based on the deep study of the concept of 3D DTM (three dimensional digital topographic map), the author further discussed the technology and core theories of 3D digital topographic map. 3D digital topographic map is actually the 3D spatial data display and visualization based on abstract symbol, it is vector map, in which relief, features and their cubic shape are represented with 3D characteristic point and characteristic line. 3D DTM unfolds geographic landscape before user with cubic modeling technique, so it can accurately reflect the spatial characteristic of geographic entity, we can acquire not only the planimetric relationship among spatial entities, but also elevation of the ground and height of ground features, users can make 3D measurement and analysis in 3D DTM. Research of 3D digital topographic map includes feature representation, terrain representation, cartography synthesizing, data acquiring, graphic processing, data management, 3D display, 3D measurement and analysis etc., in which feature representation and terrain representation are the core theories. Research of 3D DTM will powerfully promote the development of virtual reality technique and 3D GIS.