Temporally Coherent Irradiance Caching for High Quality Animation Rendering

In rendering of high quality animations that include global illumination, the final gathering and irradiance caching are commonly used. However, the computational cost they incur is high enough to discourage their wide use in production rendering. We introduce a data structure called anchor, which lets us permanently link cache locations to points intersected by their final gathering rays. Consequently, we can cheaply probe and transfer the (ir)radiance by exploiting the temporal coherence of successive animation frames, resulting in half an order of magnitude acceleration and reduced temporal artifacts. Additionally, our anchor structure lets us render moderately glossy surfaces at the cost much lower than the traditional importance sampling techniques.We also describe an efficient, perceptually motivated and independent scheme for limiting the growth in the number of irradiance caches. Finally, an implementation in a practical rendering system is demonstrated