【作者】 陈皓；

【导师】 刘晓平；

【作者基本信息】 合肥工业大学 ， 计算机应用技术， 2008， 博士

【摘要】 真实感渲染是计算机图形学一直以来的追求目标,本文在全面综述目前工作的基础上,从阴影生成、焦敞效果渲染和并行化等角度出发进行真实感渲染算法的研究,实现了不同方面的优化渲染算法,并给出了详绌的实验结果。本文以光子映射算法为基础,研究光子映射算法的光子搜索加速、焦散光子图优化以及并行化等问题,尝试将真实感全局光照渲染算法的概念应用于虚拟现实的实时渲染算法中,以提高虚拟现实的真实感。主要工作集中于以下几点:1.在阴影生成方面,提出基于投影距离的阴影图算法,对传统软阴影生成算法的视觉效果进行了改进,使得软阴影的模糊程度和阴影的投影距离相关,在保证渲染效率的基础上得到了视觉上更加真实的阴影效果。为了实现物理上更加真实的光照,在光子映射思想的基础上提出了光子纹理的概念,在纹理空间进行相邻光子的搜索和光照计算,从而加快光子映射算法的采样点辐射评估过程。2.针对真实感渲染中的焦散渲染问题,在光子映射算法的基础上提出了光子聚类的算法,目的是在保证渲染质量的前提下,尽可能的减少渲染焦散所需要的光子投射量,提出了一种在渲染速度和渲染精确度之间寻求折中的途径。3.针对光子映射算法的渲染效率问题,实现了共享内存多处理机上的并行化光子映射算法,并获得了令人满意的加速比。对不同任务分配方案进行了对比,初步地研究了光子映射并行计算中的任务分配、负载平衡等问题。更多还原

【Abstract】 Realistic rendering is always an important object of computer graphics. Based on current research, shadow generation, caustic and parallelized rendering are studied, several optimized algorithms are realized and particular experiments results are given.Based on photon mapping, accelerating of photons searching, optimize of caustic photon map and parallelization are emphasized. The concepts of realistic rendering are applied in real-time rendering of VR, in order to improve the performance of visual realistic. The main work of this dissertation is concentrated in following three aspects:1. In shadow generation, the shadow map algorithm is optimized based on projection distance, so the visual effects of traditional algorithm is improved. The blur degree and the light degree are related to the distance between the shadow and the object which cast it. Much more realistic shadow result can be generated while the rendering efficiency is kept. In order to generate the realistic shadow in nature, the concept of photon texture is proposed based on photon mapping algorithm. In photon texture algorithm, the photon collection process is completed in texture, so the rendering speed can be increased remarkably.2. In caustic rendering, photon clustering algorithm is proposed based on photon mapping, intending to decrease the caustic photons while the rendering quality can be maintained. In another word, photon clustering is a method to compromise the rendering quality and speed when doing the caustic rendering.3. Aim at the efficiency of graphics rendering, a parallelized photon mapping algorithm is realized on the share memory multi-processor cluster and satisfying speed-up can be achieved. Different assignment plans are compared and pilot studied.更多还原