Fast Filtering of Reflection Probes

Fast convolution of cubemaps with GGX filters using precomputed lookup tables that minimize L₁ error.

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BibTeX

@article{Manson:2016:GGX,
  author  = {Josiah Manson and
             Peter-Pike Sloan},
  title   = {Fast Filtering of Reflection Probes},
  journal = {Computer Graphics Forum (EGSR)},
  volume  = {35},
  number  = {4},
  year    = {2016},
  pages   = {119–127},
}

Abstract

Game and movie studios are switching to physically based rendering en masse, but physically accurate filter convolution is difficult to do quickly enough to update reflection probes in real-time. Cubemap filtering has also become a bottleneck in the content processing pipeline. We have developed a two-pass filtering algorithm that is specialized for isotropic reflection kernels, is several times faster than existing algorithms, and produces superior results.The first pass uses a quadratic b-spline recurrence that is modified for cubemaps. The second pass uses lookup tables to determine optimal sampling in terms of placement, mipmap level, and coefficients. Filtering a full 128² cubemap on an NVIDIA GeForce GTX 980 takes between 160 μs and 730 μs with our method, depending on the desired quality.

Supplemental

egsr_presentation.pptx

The presentation that I gave at EGSR

redirect.html

Coefficeint tables and HLSL code snippets on how to perform filtering are availiable on the Activision website linked here.

License

The images, executables, and code supplied are from the web page http://josiahmanson.com. These materials are free to use for non-commercial purposes. Any works that use materials from this web page should acknowledge Josiah Manson and the paper Fast Filtering of Reflection Probes. For commercial use, please contact Josiah Manson (josiahmanson@gmail.com).