Vray 3.5 Beta - Problem with VrayFastSSS2 material + Adaptive Lights

[Alex_M]

I'm getting strange results when rendering VrayFastSSS2 materials with Adaptive Lights. Please check the screenshots below as well as the 3ds max scene for inspection.

[matanov]

I get nothing when I render the scene as you sent it. Can you please check it ? Also can you try rendering it with the SSS multiple scattering set to "Raytraced" ?

[Alex_M]

Sorry, I've enabled the light include list by mistake. Just go to the Exclude option of the lights and make sure the button Exclude is active, not Include.

Anyways, I tried Raytraced for the material and the issue still persists.

[matanov]

Ok, seems like a bug. Thanks !

[vlado]

Thanks a lot for the report! Will fix it for beta 2. In the meantime, the VRayALSurfaceMtl material works fine.

Best regards,
Vlado

[vlado]

Can get me some more specific reproduction steps? It seems to work fine for me in a simple test.

Best regards,
Vlado

[Alex_M]

Can get me some more specific reproduction steps? It seems to work fine for me in a simple test.

Best regards,
Vlado

Please check the attached scene (don't use the one in my 1st post, I forgot to set it up properly for the test). Just load this new scene in Max and hit render. I tested it on 2 workstations and on both Vray renders the SSS object with black patches like in my first post if Adaptive lights is used.

[vlado]

Ok, yes I can see the issue. Like I said will fix it; in the meantime you can use the VRayALSurfaceMtl material.

Best regards,
Vlado

[Alex_M]

Now that the changelog of Beta 2 is released, I took a quick peek at it and found a couple of things that are still not working for me. One of them is the problem with VrayFastSSS2 materials and Adaptive lights. Maybe I'll have to check out the ALSurface material as a workaround for the time being as you suggested.

The image below is a test with Beta 2:




From the link above:

Hello,
Here is the changelog:
Build 3.50.02 (beta) (11.01.2017)
==============

Bug fixes:
...
(*) V-Ray: Artifacts with adaptive lights and VRayFastSSS2 material;
...

[matanov]

The fix is applicable only for Raytraced scattering of the VRayFastSSS2. Try to avoid the prepass mode, it can lead to undesirable effects with the new algorithms.

[Alex_M]

Ok, got it. It does work fine with raytraced scattering. I'll try to remember to avoid prepass mode with Adaptive lights.

By the way, this particular scene has 150 lights and renders 3 times faster with Adaptive lights. Good job!

[matanov]

Nice

We will think of a way to warn the users about the prepass+AL.