Exploiting Temporal Coherence in Final Gathering for Dynamic Scenes

Efficient global illumination computation in dynamicallychanging environments is an important practical problem.In high-quality animation rendering costly "final gathering"technique is commonly used. We extend this techniqueinto temporal domain by exploiting coherence betweenthe subsequent frames. For this purpose we store previouslycomputed incoming radiance samples and refreshthem evenly in space and time using some aging criteria.The approach is based upon a two-pass photon mapping algorithmwith irradiance cache, but it can be applied alsoin other gathering methods. The algorithm significantly reducesthe cost of expensive indirect lighting computationand suppresses temporal aliasing with respect to the stateof the art frame-by-frame rendering techniques.