Research And Implementation Of Virtual Terrain Generation Technology Based On OpenGL

The generation technology for virtual terrain is a hot topic which attracts more and more researchers' attention at present. It has been widely used in simulation of battlefield, VR, landscape, programming of city, outdoor games, movie production, etc. The thesis focuses on the theoretical and methodological studies in the following subtopics: terrain data acquirement, fractal terrain simulation, 3D terrain rendering, terrain simplification and multi-resolution terrain representation, realtime optimization, and terrain texture synthesis. The major contribution includes:1. Based on OpenGL library and its work principle, the process of 3D surface rendering is analyzed at length, including modeling, spatial transform, illumination processing, visible area determination and shading. Some methods are presented to improve rendering effects and to speed up graphic display.2. The different kinds of terrain data are examined and compared, and a method for terrain data synthesis is designed. The method amalgamates fractal data, noise data and some data from terrain heightmap, and achieves more flexibility in controlling terrain attributes.3. The technology for realtime multi-resolution terrain rendering is analyzed in detail. A new simplification criteria is presented on the basis of Lindstrom's criteria. The experimental results indicate that the new criteria is efficient and can solove the triangle redundancy when rendering the coplanarity incline.4. A realtime multi-resolution terrain-rendering frame structure is established. It employes longest-edge bisection, and contains a series of operation such as establishing nested hierarchy sphere, realtime refinement, view frustum culling, geomorphing. Meanwhile, memory-mapping and multithread technologies are also adopted.5. Multi-layers surface texture synthsesis and multi-resolution terrain texture reprentation are realized. On the constraints of terrain data, by using of image synthesis technology, texture can be synthesized in a hierarchy structure. Tests show that the method can generated realistic terrain texture, and the texture can be display in a multi-resolution in roaming.