vfs6; Wrapped materials will fail when the atmospheric environment or ambient fog is turned on.

V-Ray V-Ray for SketchUp Issues
1

vfs6;当大气环境或环境雾打开时，包裹的材料将失效。

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Hi @cq_x ​,

This is a known limitation and not something we can easily change.
The thing is that after the camera ray hits a Wrapper / Matte object it samples the Background color directly missing the fog behind the object completely.

Konstantin