A fast relighting engine for interactive cinematic lighting design

We present new techniques for interactive cinematic lighting design of complex scenes that use procedural shaders. Deep-framebuffers are used to store the geometric and optical information of the visible surfaces of an image. The geometric information is represented as collections of oriented points, and the optical information is represented as bi-directional reflection distribution functions, or BRDFs. The BRDFs are generated by procedurally defined surface texturing functions that spatially vary the surfaces' appearances. The deep-framebuffer information is rendered using a multi-pass algorithm built on the OpenGL graphics pipeline. In order to handle both physically-correct as well as non-realistic reflection models used in the film industry, we factor the BRDF into independent components that map onto both the lighting and texturing units of the graphics hardware. A similar factorization is used to control the lighting distribution. Using these techniques, lighting calculations can be evaluated 2500 times faster than previous methods. This allows lighting changes to be rendered at rates of 20Hz in static environments that contain millions of objects of with dozens of unique procedurally defined surface properties and scores of lights.