Question about subsurface scattering about optix-pathtracer

[knightcrawler25]

The BRDF model used here is from this paper:

https://blog.selfshadow.com/publications/s2012-shading-course/burley/s2012_pbs_disney_brdf_notes_v3.pdf

A paragraph from it reads:
"Our subsurface parameter blends between the base diffuse shape and one inspired by the HanrahanKrueger subsurface BRDF. This is useful for giving a subsurface appearance on distant objects
and on objects where the average scattering path length is small; it’s not, however, a substitute for
doing full subsurface transport as it won’t bleed light into the shadows or through the surface"

The one Blender Cycles and PBRT v3 use is a newer model with path traced subsurface scattering, which is probably why you do not see the same results when you compare it with Cycles:
https://blog.selfshadow.com/publications/s2015-shading-course/burley/s2015_pbs_disney_bsdf_notes.pdf

[straaljager]

Thanks for the clarification. In that case I will try to implement the Cycles SSS shader myself.

Cheers!

[knightcrawler25]

You can have a look at Tinsel (https://github.com/mmacklin/tinsel) for some implementation details on the Principled shader.

[straaljager]

The SSS in the Tinsel screenshot looks more realistic indeed, Will have a look, thanks.