Exploiting temporal coherence in final gathering for dynamic scenes

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