路径追踪算法

Path tracing is one of several techniques to render photorealistic im- ages by simulating the physics of light propagation within a scene. The roots of path tracing are outside of computer graphics, in the Monte Carlo simulations developed for neutron transport. A great strength of path tracing is that it is conceptually, mathematically, and often-times algorithmically simple and elegant, yet it is very general. Until recently, however, brute-force path tracing techniques were simply too noisy and slow to be practical for movie production rendering. They therefore re- ceived little usage outside of academia, except perhaps to generate an occasional reference image to validate the correctness of other (faster but less general) rendering algorithms. The last ten years have seen a dramatic shift in this balance, and path tracing techniques are now widely used. This shift was partially fueled by steadily increasing com- putational power and memory, but also by significant improvements in sampling, rendering, and denoising techniques. In this survey, we pro- vide an overview of path tracing and highlight important milestones in its development that have led to it becoming the preferred movie rendering technique today.