Research On Real-Time Rendering Technique Of The Large-Scale Terrain/Vegetation

Natural sceneries, such as terrain and vegetation, are important components in virtual reality. However, the models of natural sceneries are usually very complicated including a lot of surface details, so the data storages are large, which leads to the difficulty of fast rendering. When users are roaming in the natural scene, they often concentrate on the whole effect because of the vast visual field of the scene. Furthermore, since the distinguishing ability of human vision is limited, even though the spatial positions of the model polygons are deflective from their original ones, it is hard to observe the differences in vision. Therefore, according to the characteristics of the natural sceneries and the ones of human vision, we propose a sampling and approximate scheme in this thesis. The approximate model is obtained by sampling the natural scene in preprocessing stage, and the scene is reconstructed in rendering stage by the model. The reconstructed result approximates the original scene, and the approximate parameters could modulate the errors between them. In this thesis, we apply the scheme to rendering of large-scale terrain and vegetation, and achieve three research results as follows.Terrain is the basic component of the natural scene. The model storages of the traditional approaches are usually very huge, which restricts the application of terrain rendering techniques. A procedural approximate and rendering technique of terrain is presented in this thesis, which could render the large-scale terrain scene with less data storage. The hierarchical tree structure of terrain including the fractal information is constructed in preprocessing stage, and then in rendering stage, the view-dependent terrain meshes are generated through GPU according to the user-defined threshold. The fractal hierarchical tree model approximates to the original terrain, thus the higher data compressed ratio could be achieved. Experiments demonstrate that the approach could be used in several areas, such as terrain compression and terrain synthesis.Adding vegetation, such as trees, into the virtual scene could make the rendering result more vivid. Trees contain complex structures and abundant details. Because forest contains lots of trees, if each tree was rendered respectively, the rendering al-...