Replica exchange light transport on relaxed distributions

ABSTRACT

Developing a robust method for computing global illumination is a challenging problem. A Markov chain Monte Carlo (MCMC) method, like [Jakob and Marschner 2012], samples the light path space with a probability proportional to the per-path contribution, by successively mutating path samples (e.g., perturbing a reflection direction). In practice, a path sample could get stuck in a high energy peak for multiple mutations, resulting in a bright spot artifact. To resolve this problem, we present a new unbiased rendering framework based on a replica exchange technique [Kitaoka et al. 2009], a variant of MCMC technique. A replica exchange technique incorporates a set of different distributions. We propose to introduce a set of relaxed distributions, which are beneficial for reducing the chance of getting stuck.

References

1. Jakob, W., and Marschner, S. 2012. Manifold exploration: a markov chain monte carlo technique for rendering scenes with difficult specular transport. ACM Trans. Graph. (SIGGRAPH 2012) 31, 4, 58:1--58:13.
2. Kelemen, C., Szirmay-Kalos, L., Antal, G., and Csonka, F. 2002. A simple and robust mutation strategy for the metropolis light transport algorithm. Computer Graphics Forum (EUROGRAPHICS 2002) 21, 3, 531--540.
3. Kitaoka, S., Kitamura, Y., and Kishino, F. 2009. Replica exchange light transport. Computer Graphics Forum 28, 8, 2330--2342.