Stencil Buffer Based Shadow Computations for Dynamic Environments

• Main Authors: Kuo, Jiun-Long, 郭俊隆
• Other Authors: Chuang Jung-Hong
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/03800143383011941229

碩士 === 國立交通大學 === 資訊工程學系 === 86 === In dynamic environments, shadows not only improve the image quality of the scene, but also enhance the perception of spatial relationships. In this thesis, we purpose an object-based hard shadow computation method for dynamic environments. First, we attempt to find the contour (silhouette), called effective shadowing contour (abbreviate ESC), for each object and each point light source. The shadow volumes are constructed by the effective shadowing contours. Next, we find occlusion relationships between objects in the scene by some methods similar to shadow tiling algorithm and painter's algorithm. Finally, we use stencil buffer to generate shadows. Moreover, we purpose speed-up methods for dynamic environments, such as local update of scene change, normal mask for light-face/back-face testing, frame coherence exploration for ESC computation, and occlusion culling for reducing the number of the polygons needed for shadow computation. According to our experiments, the stencil buffer based method is more efficient than shadow volume binary space partition tree (SVBSP tree) based algorithm. we also compare three stencil buffer based methods, and try to conclude with a suitable architecture for shadow computations.