Adaptive Lightslice for Virtual Ray Lights

During my first masters project, I investigated whether it was possible to accelerate the virtual ray light algorithm by clustering the VRLs. For this project, I implemented Virtual Ray Lights in Mitsuba, and added an adaptive version of the Lightslice algorithm to it. That last one is an existing technique for clustering Virtual Point Lights. The results of my implementation were pretty good, which resulted in a great mark (95%) and my thesis published as a poster during EGSR 2014 and a short paper at Eurographics 2015.


We speed up the rendering of participating media with Virtual Ray Lights (VRLs) by clustering them in a preprocessing step. A subset of representative VRLs is then sampled from the clustering, which is used for the final rendering. By performing a full variance analysis, we can explicitly estimate the convergence rate of the rendering process and automatically find the locally ideal number of clusters to maximize efficiency. Overall, we report speed-up factors ranging from 13 to 16 compared to unclustered rendering.

Authors: Roald Frederickx, Pieterjan Bartels, Philip Dutré

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