Blender Git Commit Log

Git Commits -> Revision a94343a

Revision a94343a by Brecht Van Lommel (master)
October 11, 2021, 16:22 (GMT)
Cycles: improve SSS Fresnel and retro-reflection in Principled BSDF

For details see the "Extending the Disney BRDF to a BSDF with Integrated
Subsurface Scattering" paper.

We split the diffuse BSDF into a lambertian and retro-reflection component.
The retro-reflection component is always handled as a BSDF, while the
lambertian component can be replaced by a BSSRDF.

For the BSSRDF case, we compute Fresnel separately at the entry and exit
points, which may have different normals. As the scattering radius decreases
this converges to the BSDF case.

A downside is that this increases noise for subsurface scattering in the
Principled BSDF, due to some samples going to the retro-reflection component.
However the previous logic (also in 2.93) was simple wrong, using a
non-sensical view direction vector at the exit point. We use an importance
sampling weight estimate for the retro-reflection to try to better balance
samples between the BSDF and BSSRDF.

Differential Revision: https://developer.blender.org/D12801

Commit Details:

Full Hash: a94343a8afcac5d6db09c8461e67ad1ba5a85d35
Parent Commit: 73a05ff
Lines Changed: +125, -77

10 Modified Paths:

/intern/cycles/kernel/closure/bsdf.h (+0, -6) (Diff)
/intern/cycles/kernel/closure/bsdf_principled_diffuse.h (+63, -15) (Diff)
/intern/cycles/kernel/closure/bssrdf.h (+21, -9) (Diff)
/intern/cycles/kernel/integrator/integrator_shade_surface.h (+2, -2) (Diff)
/intern/cycles/kernel/integrator/integrator_state_template.h (+0, -1) (Diff)
/intern/cycles/kernel/integrator/integrator_subsurface.h (+22, -22) (Diff)
/intern/cycles/kernel/kernel_shader.h (+4, -7) (Diff)
/intern/cycles/kernel/kernel_types.h (+11, -9) (Diff)
/intern/cycles/kernel/svm/svm_closure.h (+2, -2) (Diff)
/intern/cycles/kernel/svm/svm_types.h (+0, -4) (Diff)
By: Miika HämäläinenLast update: Nov-07-2014 14:18MiikaHweb | 2003-2021