Fast Filtering of Reflection Probes
Josiah Manson, Peter‐Pike Sloan · Computer Graphics Forum · 2016
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 out method, depending on the desired quality.