Studying And Realization Of Three-Dimension Terrain Visualization

The visualization and real-time rendering of three-dimension (3D) terrain surface are hot research topics in geographic information system (GIS), digital photo-grammetry (DP), virtual reality (VR) and other associated fields. It has attracted increasingly attention in recent years because of wide application backgrounds. It is a subject about the display, simplification, simulation of Digital Terrain Mode or Digital Height Field. It is a part of computer graphics.This thesis focuses on the theoretical and methodological studies in several subtopics: (1) digital terrain model (DTM) creation, (2) 3D terrain rendering, (3) terrain simplification, (4) multi-resolution terrain representation and (5) terrain cutting. These studies are based on some interdisplines such as 3D computer graphics, computer geometry, scientific computation visualization, virtual reality. The main results of this study are summarized as follows:(1) The method of generating DTM is examined in detail. An improved algorithm in building Delaunay TIN is recommended; and then trail and draws the contour based on the TIN.(2) Based on DirectX8 library (Direct3D8) and its work principle, the process of 3D surface rendering is analyzed at length, including modeling, spatial transform, illumination processing, visible area determination, background culling, shading, and texture mapping, and then realized 3D real terrain on this basis. The voxel-based terrain rendering technique is also discussed.(3) After discussing refinement and simplifiment of 3D terrain model in common, we have realized it on the base of its theory.(4) On the basis of terrain cutting theory in real data, the cutting model and rebuilding-terrain model are realized.