MDL in Omniverse RTX and multiscatter_tint?

hope this is the right place to post this (the Omniverse specific forums seem a bit lacking in MDL conversation!)

I noticed in some white furnace test in Create (Omniverse) that my own hand rolled MDL materials - and indeed the built in PBR surface - exhibit the traditional darkening on grazing angles at high roughness - presumably due to microfacet shadowing BSDF’s

In the MDL docs however there is a specific term added to compensate for this (multiscatter_tint: color (1.0))
Using it doesn’t seem to have any effect in Create - but it doesn’t throw up any compiler errors either…

can anyone from Nvidia confirm if this just isn’t implemented in Create right now?

example below illustrates the problem:

Screenshot 2021-04-19 222713

Simple diffuse (Oren Nayar) plus glossy specular (GGX) bsdf’s (both of which are microfacet models) set to 0.8 roughness

If this was energy conservative I presumably shouldn’t be getting any darkened areas on these spheres? (my shader on the left, Creates native PBR shader on the right)

setting multiscatter_tint seems to have no effect at all

When talking create, we need to differentiate between RTX realtime and RTX pathtrace. Pathtrace uses the full code from the MDL SDK and should support Multiscatter Tint. Realtime does approximate some things and does currently not support multiscatter tint. This is requested but i dont have an ETA for that.