| Summary: | 碩士 === 國立交通大學 === 資訊工程系 === 88 === Abstract
Real-time and smooth rendering of a large-scale terrain data has been a challenging problem. In this paper, we propose a geometrically continuous view-dependent level-of-detail (LOD) modeling aiming to speed up the generation of terrain mesh and in the meantime achieve a satisfied image quality. The terrain data is subdivided into blocks and each of which will possesses its own LOD mesh that is dynamically determined according to the viewing parameters. Between two adjacent blocks, a dike structure is proposed that aims to provide a smooth blending between two meshes of different levels of detail, and hence remove cracks that usually occur in previous methods. We also propose a mechanism in LOD modeling that caches the LOD of a block for the possible reuse in the following frames after it is generated. Since LOD selection and generation in general requires computation on each node level, such a LOD caching can potentially contribute a considerable saving of computation time. We also implement several speed-up methods, such as view culling and texture mapping, and others that utilize spatial and temporal coherence. The proposed view-dependent LOD modeling techniques will be useful in building a terrain rendering system that has applications in the areas such as flight simulation and GIS.
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