Cycles: Improve backscatter color of subsurface scattering in Principled BSDF
ClosedPublic
Actions

Authored by Pascal Schön (VanCantus) on May 24 2017, 8:40 AM.

Details

Reviewers

Brecht Van Lommel (brecht)

Group Reviewers

Cycles

Commits

rCba586b50d1aa: Improve backscatter color of subsurface scattering in Principled BSDF
rBSc91d2d30dfc1: Improve backscatter color of subsurface scattering in Principled BSDF
rBc91d2d30dfc1: Improve backscatter color of subsurface scattering in Principled BSDF

Summary

The albedo of the subsurface scattering in the Principled BSDF was just a blend between the base and subsurface color. The albedo was also used for weighting the BSSRDF closures. This caused a constant backscatter color.

With this patch, the subsurface color is applied as the albedo and the blended color is only used for weighting the closures, which results in physically plausible backscatter colors, depending on the depth of the subsurface scattering rays.

Here is a comparison with base color = (0.0, 1.0, 1.0) and subsurface color = (1.0, 0.0, 0.0):

This patch:

Diff Detail

Event Timeline

Pascal Schön (VanCantus) created this revision.May 24 2017, 8:40 AM

Pascal Schön (VanCantus) added a reviewer: Cycles.

Pascal Schön (VanCantus) mentioned this in T51589: Principled Subsurface Scattering, wrong shadow color.May 24 2017, 8:45 AM

The behavior change looks good to me.

Can't we avoid passing base_color and radius to bssrdf_principled in OSL? To me seems like these could just be used in the shader to adjust the closure weight and radius.