Noisy speckles in multimatte when gamma/exposure up the render element

V-Ray V-Ray for Maya Issues
1

Hi,

Recently we have to gamma/exposure up some of the multimattes to address certain edging issue. We find when doing that (exposure up multimattes) there are sparse noise in, for example, the green channel like green speckles. These multimattes are material ID mattes.

For example, a car seat that is assigned with VrayMtl 1 with mat id 2 for multimatte 1.

When render the car from an exterior angle, I see sparse green speckles where the seat should be completely occluded by the exterior car paint. Again, these speckles are not visible to bare eyes until I exposure/gamma up the multimatte channel in Nuke.

Is it normal in Vray to output multimattes this way? I expect if an object is behind solid (non-transparent) objects, its material matte should be completely black?

Thanks,
Jason

2

In your reflection of the vray material, what is ‘affect channels’ set to?
It’s probably the slight reflection of one of the multimattes.

3

For the seat, in the material, it’s set to “affect color” for reflection and no refraction.

4

This might be a bug. Can you get me a reproducible scene?

Best regards,
Vlado

5

Hi Vlado, I have sent you an email regarding uploading the simplified scene for debugging. Look forward to hearing back.

Thanks,
Jason

6

Thanks, I asked the support guys to send you info how to upload the scene. Let me know if you don’t hear from them.

Best regards,
Vlado

7

Great. I will keep you posted. Thanks, Vlado.

- Jason

8

Hey Vlado and the team,

Just want to follow up on this issue. I’ve uploaded the simplified scene to your FTP two weeks ago and wondering if you have been able to replicate the issue on your end and if the bug is addressed?

Thanks,
Jason

9

I found the ticket in our system and one of my colleagues has already replied to it on August 20. Please check the spam folder of your email account.
We are going to send new mail right now so please let us know as soon as you receive it.

Thanks for the remainder.