Two-stage Resampling for Bidirectional Path Tracing with Multiple Light Sub-paths
| Kosuke Nabata |
Kei Iwasaki |
Yoshinori Dobashi |
| Wakayama University |
Wakayama University |
Hokkaido University |
|
Prometech CG Research |
Prometech CG Research |
|
Abstract:
Recent advances in bidirectional path tracing (BPT) reveal that the use of multiple light sub-paths and the resampling of a small number of these can improve the efficiency of BPT.
By increasing the number of pre-sampled light sub-paths, the possibility of generating light paths that provide large contributions can be better explored
and this can alleviate the correlation of light paths due to the reuse of pre-sampled light sub-paths by all eye sub-paths.
The increased number of pre-sampled light sub- paths, however, also incurs a high computational cost.
In this paper, we propose a two-stage resampling method for BPT to efficiently handle a large number of pre-sampled light sub-paths.
We also derive a weighting function that can treat the changes in path probability due to the two-stage resampling.
Our method can handle a two orders of magnitude larger number of pre- sampled light sub-paths than previous methods in equal-time rendering,
resulting in stable and better noise reduction than state-of-the-art methods.
Resources
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supplemental (derivation of variance, weighting functions)
supplemental images