No direct light visible in interiors with adaptive lights and SSS-Materials

[B_Loeffler]

Hello!

We are encountering some issues with adaptive lighting and SSS materials receiving proper direct light in interior scenes. We're using V-Ray for 3ds Max version 6.20.03, build 32518.

The scene setup is as follows:

Camera:
V-Ray Physical Camera positioned inside a building

Lighting:
Domelight with HDRI as the main light source Several other lights representing artificial lighting within the building

Geometry:
A "normal" living room with both open and closed windows

Rendersetting:
image sampler: Bucket
adaptive lights (16)
GI: LC+IM / LC+BF


I've encountered similar issues in two scenes like the one described above.
In both cases, the direct lighting was incorrect (though it appeared correctly in the light cache). Upon investigation, I found that objects above the camera with FastSSS materials were causing the problem.
Switching the material to a normal V-Ray material resolved the issue.

The scene rendered correctly when I moved the object with the FastSSS material below the scene's ground or switched to full light evaluation.

Could someone confirm this peculiar behavior? Is there already a fix available for the used V-Ray version (6.20.03, build 32518 )?
If further explanation is required, please let me know.

Thank you in advance.
Best regards,
Bernhard

[vladimir_krastev]

Hi, thanks for posting. Please send us a scene that illustrates the issue. You can do that here or trough the ticketing system. If you choose the ticketing system please add a link to this thread in your message to support.

[vladimir_krastev]

Hi, there is and issue with your scene that needs to be reviewed more carefully by our developers. We've reported it under VMAX-14157.
Please switch your VRayFastSSS2 material's scattering options from raytraced to simple as a temporary workaround.