EEVEE-Next: Sphere Probe convolution #118256

New Issue

Clément Foucault · 2024-02-14T12:13:53+01:00

Clément Foucault commented

2024-02-14 12:13:53 +01:00

In the legacy EEVEE implementation, we used to convolve the sphere probe with the GGX distribution. This isn't practical for EEVEE-Next as we aim to support multiple BSDF using the same light probe (Toon, Refraction, Velvet etc...).

Since it would be hard to fit any BSDF model to GGX, we should use spherical Gaussian lobe which is easier to fit and do combinations of (i.e: sum of Gaussian for Toon BSDF or better GGX). Also, this would remove much of the noise created by the GGX long tail at lower roughness. This isn't a huge problem since the light probe are aimed at lower quality lighting (the ray-traced solution will still exhibit this famous "long tail").

Tasks

Implement custom down-sampling using spherical Gaussian lobe.
- da72cdee5e Add custom down-sampling shader & pipeline (bilinear just like the current solution)
- #118354 Add spherical Gaussian implementation and fine tune each level of blurring.
  - Add Gaussian weights.
  - Fine tune blur level.
Fit BxDFs models to the chosen Gaussian lobes.
- Fit GGX BRDF
- #118533 Fit GGX BTDF

In the legacy EEVEE implementation, we used to convolve the sphere probe with the GGX distribution. This isn't practical for EEVEE-Next as we aim to support multiple BSDF using the same light probe (Toon, Refraction, Velvet etc...). Since it would be hard to fit any BSDF model to GGX, we should use spherical Gaussian lobe which is easier to fit and do combinations of (i.e: sum of Gaussian for Toon BSDF or better GGX). Also, this would remove much of the noise created by the GGX long tail at lower roughness. This isn't a huge problem since the light probe are aimed at lower quality lighting (the ray-traced solution will still exhibit this famous "long tail"). #### Tasks - [x] Implement custom down-sampling using spherical Gaussian lobe. - [x] da72cdee5e9a00116425f2b24dfd90b785d257c9 Add custom down-sampling shader & pipeline (bilinear just like the current solution) - [x] #118354 Add spherical Gaussian implementation and fine tune each level of blurring. - [x] Add Gaussian weights. - [x] Fine tune blur level. - [x] Fit BxDFs models to the chosen Gaussian lobes. - [x] Fit GGX BRDF - [x] #118533 Fit GGX BTDF

Clément Foucault added this to the 4.2 LTS milestone 2024-02-14 12:13:53 +01:00

Clément Foucault added the

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EEVEE-Next: Sphere Probe convolution #118256

Tasks