LPEs & ALSurface

[Druski]

Are there any know issues using LPE's to isolate the SSS component for a specified light when using the ALSurface material? I have tried the following operations, neither have worked correctly:

C<TD>.+L

C<[RT][SG]>*<TD>.+L

It would appear some secondary influence on the SSS material, perhaps from GI/Indirect rays is missing.

Given my goal is mainly to isolate the lights specular contribution, I even tried subtracting from the Full lights contribution, but this lead to the same outcome, missing the indirect data.

C.*L-C<R[GS]>L-C<R[GS]>.+L

Any assistance, or clarification in relation to this would be greatly appreciated.

[hermit.crab]

Yes, some of the presets need to be updated. We're already aware of it (internal bug-tracker id: VMAYA-10873) and I'll bump its priority further. Otherwise, this LPE should work:

C<TD>(.+L|.*[OB])

[Druski]

Thanks so much! That expression definitely got me closer, but there is still some indirect bounce missing when compared with the Full Light Select output.

Any ideas how to get better coverage?

I can try and put some examples together for you, if your not able to reproduce on you end. It definitely has something to do with indirect rays generated by diffuse (non-SSS) surfaces.

[hermit.crab]

That expression definitely got me closer, but there is still some indirect bounce missing when compared with the Full Light Select output.

What do you mean? The Full Light Select includes the GI from the specific light only (not the environment GI), so maybe that's the reason.
Otherwise, yes do attach (or send) a simple scene and screencaps illustrating the issue.

[vlado]

The full light select actually does include the SSS GI component. It would be great to see some examples with the differences.

Best regards,
Vlado

[Druski]

Yes indeed - The Full Light Select is correct, it's the LPE i'm using to isolate the SSS that's missing the data. I'll produce some examples that I can share here. I am unable to share my current examples in a public forum.

[Druski]

So turns out, the incorrect GI contribution was due to the Light Cache, in BF|BF mode it works as expected. It is in the documentation, but I missed that obviously. There is obviously a time penalty associated with this though, are there plans to get Light Cache to work correctly with LPEs?

I would like also like to point out that I was unable to get LPE's constructed using the lpe-builder weblink to work at all, I keep getting parsing errors in the script editor. I have been able to construct in other ways, but just thought I should flag here.