Practical Interactive Lighting Design for RenderMan Scenes

This thesis develops a novel technique to enable interactive rendering during lighting design of feature film-quality computer graphics specified in the industry standard RenderMan Interface. This technique is designed to maximize the fidelity of the preview to the results of final-frame rendering, while achieving interactive performance. The technique presented achieves interactive performance through three critical optimizations. First, it dramatically reduces the computational cost of rendering sequential lighting previews by caching all light-independent computation and only recomputing the portion of the shading which depends on the lighting parameters being edited by the user. Second, it improves performance in common film scenes containing many lights by caching the shading contribution of all inactive lights and only recomputing the shading for the light currently being edited. Third, it achieves extremely high performance on re-rendering computation by mapping it to efficient data-parallel computations which are executed on programmable graphics hardware. This technique is supported in practice by a novel RenderMan Shading Language compiler which presents an accurate and automated mechanism for the creation of such interactive lighting design previews from arbitrary RenderMan scenes. The compiler employs global data flow analysis to compute a precise lighting specialization of arbitrary RenderMan shaders. It uses this analysis to generate complementary precomputation and re-rendering shaders. The precomputation shaders are executed in place of the original shaders in a rendering of the scene through the final software renderer. The re-rendering shaders are executed in real-time in a generalized interactive lighting design framework which employs the techniques presented herein. This technique accelerates preview rendering for lighting design by more than three orders of magnitude on real-world scenes, while requiring no modification to existing production pipelines and maintaining complete fidelity to the final results being previewed.