| Photorealistic rendering technology of computer graphics is an important issue. Realistic light effect is main objective of photorealistic rendering technology and the material attribute is the key problem. At present, the method which can well simulate the illumination properties of the materials is based on photos. The main research can divide into three catalogues: Reverse drawing, Image-based relighting, Light sampling based on material samples. Reverse drawing can compute the material parameters of the object, but hard to achieving real time rendering of the global illumination. It also requires strict light condition. Image-based relighting requires many samples, and hard to rebuild the high-frequency components of the light on the surface. Light sampling based on material samples acquires many samples under different light position and view position. This method can divides into two main methods: BRDF and BTF. All these two methods need huge data, and require efficient compression method.This thesis focus on Light sampling based on material samples, and do many researches include BRDF, Texture Mapping, and the approximate BTF. Following will list the main results:1. Combine diffuse map and BRDF technology. Enhance texture detail of the surface.2. Use parabolic texture mapping technology to save the compressed data from raw images. Use this technology which is not relevant to view position will not produce singularity points and can make more effective to interpolating between any reflect orientations.3. Use MIPMAP technology which improved aliasing problem caused by texture interpolation.4. Combine with LOD technology, make it can use in complex scene.5. Advanced a method called approximate BTF which based on points. This method only uses a few of pictures and can good to retain the surface texture of the material details, such like self shadow ,self block and so on.The method advanced in this article can use in many areas such as game, virtual realistic and so on. |
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