Thin Walled SSS Geometry is destroying mattes

[infoMMJ2X]

Hi Guys,

I need masks for a project right now and I've come to the conclusion that Objects with Thin Walled SSS are receiving illumination from the mattes and/or are computing the subsurface effects, so the masks are unusable.

Once I turn thin walled off everything works as expected.

I've attached a screenshot showing how a matte looks with thin walled sss geometry in it.

Thanksthinwalledsss.jpg

[peter.horvath6V6K3]

Can you send me a scene or some screenshots of the shader parameters?

[infoMMJ2X]

Hi Peter,

I've attached a scenefile for you - I don't believe this is intentional behaviour. If it is, I think it would be nice to have something like a "Transmit AOV" checkbox for SSS. But as the standard SSS isn't showing this effect I think it might be a bug.

Thanks for looking into it!

Cheerssss-matte.zip

[peter.horvath6V6K3]

Could you please post me a screenshot of the issue in the shared scene? Only the camera rays are written to a custom AOV, no indirect, so it should look fine and I don't see any problems in your Multimatte AOV. Looks the same with or without Thin Walled enabled. Maybe I just overlook something.

[infoMMJ2X]

http://www.christian-behrendt.com/img/screens/2018-02-22_180544.jpg

This is how the multimatte looks for me.

[peter.horvath6V6K3]

That's weird, this is what I've got in the IPR:

What's your C4DtoA version? Win or OSX?

[infoMMJ2X]

I'm on 2.2.2.3 still, on C4D R18 and Win7 64bit.

[peter.horvath6V6K3]

OK, I've got it. It looks correct in the IPR, but not in the Picture Viewer. Which is odd. Seems like a bug, and reminds me of an issue with the object masks reported earlier. I'll take a look.

[peter.horvath6V6K3]

Supposed to be fixed in C4DtoA 2.3.1 (Arnold core 5.1.1.0).