Transmission in aiStandardHair

[dave.cookL6ZQU]

Can someone please explain to me the relationship between the Transmission and Specular attributes in the aiStandardHair shader? Currently it seems as if the base model is completely specular (ignoring the diffuse and emissive components), and the transmission is completely bundled with the specular in the specular aov.

It would be useful to be able to separate the two in aovs, for diagnosing the render and for comp...would it be possible to use LPEs to create a separate them, or to maybe put the transmission into (ahem) the transmission aov?

Thanks!

(MtoA 3.1.2.1 with Maya 2018.4)

[Stephen.Blair]

Think of transmission as "transmit specular". The two speculars and transmission are all part of the specular reflectance model for hair.

To get separate LPEs for things like the hair transmission, the standard hair shader has to set a custom label (like the "hair" label that it already does). We've got a ticket for that, but no ETA right now...

[dave.cookL6ZQU]

Hi Stephen

Thanks for the reply - love the diagram!