Jaroslav Křivánek

On-line Learning of Parametric Mixture Models for Light Transport Simulation

Jiří Vorba
Charles University in Prague
Ondřej Karlík
Charles University in Prague
Martin Šik
Charles University in Prague
Tobias Ritschel
Max Planck Institut Informatik
Jaroslav Křivánek
Charles University in Prague

Plain Bidirectional path tracing (BDPT) Our guided BDPT

Comparison of the result of plain bidirectional pah tracing (BDPT) and BDPT guided by our parametric distributions trained in 30 training passes in one-hour rendering of a scene featuring difficult visibility. The results show that the time spent on distributin training is quickly amortized by the superior performance of the subsequent guided rendering.


Monte Carlo techniques for light transport simulation rely on importance sampling when constructing light transport paths. Previous work has shown that suitable sampling distributions can be recovered from particles distributed in the scene prior to rendering. We propose to represent the distributions by a parametric mixture model trained in an on-line (i.e. progressive) manner from a potentially infinite stream of particles. This enables recovering good sampling distributions in scenes with complex lighting, where the necessary number of particles may exceed available memory. Using these distributions for sampling scattering directions and light emission significantly improves the performance of state-of-the-art light transport simulation algorithms when dealing with complex lighting.


Jiří Vorba, Ondřej Karlík, Martin Šik, Tobias Ritschel, and Jaroslav Křivánek.   On-line Learning of Parametric Mixture Models for Light Transport Simulation.   ACM Trans. Graph., SIGGRAPH 2014. ... DOI | BibTeX

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Image Comparisons

Living room
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The work was supported by Charles University in Prague, project GA UK No 580612, by the grant SVV–2014–260103, and by the Czech Science Foundation P202-13-26189S. We thank Jan Beneš, Alexander Wilkie, and Iliyan Georgiev for their feedback on the paper draft and to Ludvík Koutný for providing us with the Living Room scene.

We have used these two renderers: