GPU matteshadow alpha problems

[leabum]

When I apply matte surface objectproperties or a MTL Wrapper in my current scene to catch shadows, the render either stops after two seconds leaving me with a noisy result, if the properties are applied to everything in the scene OR it keeps rendering the beauty but leaving the alpha which contains the shadow information absolutely noisy. That is when I have both matte surfaces and 'non-matte surface' objects in the same scene/renderlayer. What could be a reason for that? Why is it keeping rendering the beauty but doesn't update the alpha accordingly? thx

[goyko]

Hi, it would be great if you send a scene over to deyan.ivanov@chaosgroup.com

We will look into that asap

[jasonhuang1115]

Would like to bump up this up. I am having the same issue using Vray 3.52.02, Maya 2017 update 3, Win 10.
leabum, have you found a solution?

[goyko]

Hi, try increasing the ray bundle size and rays per pixel as that will influence the noise positively. The way matte alpha is calculated is a bit different from standard alpha for non-matte hits. That is the reason some noise is expected. We are looking for a way to overcome this, but it is not trivial.

[jasonhuang1115]

Hey goyko, I suppose you are referring to IPR setting as that's where I can find ray bundle size and rays per pixel settings.
I am talking about final frame rendering with CPU in bucket Sampler type. Is there a way to get rid of the noise in matte alpha for CPU Bucket production rendering?

Thanks!

[jasonhuang1115]

Sorry Goyko, I just realized that the thread title specifies it's related to GPU. I will probably create another thread as the problem I am having is related to CPU rendering.