Normals and Decals create artifacts

[mathieu_boch]

Hello,

when I apply a Decal on surface with normal bump. Troubles appear when camera is close to the ground.
Borders of the decal "flip" one axis of the normal as you can see.


Scene file is in attachment

Thank's for your answers.

[fixeighted]

Whilst I can't quite figure out what is causing this particular issue, you can always use the mask as opacity in the base shader and the issue will go away, if that's any use to yo.

EDIT: Actually no it doesn't, it just lessens it.

EDIT: With this similar clean setup it doesn't happen. Also, your scene crashes my machine a bit when tweaking, so maybe there's something else going on.

[mathieu_boch]

I try with your scenefile, and the bug is still here. I added 2 red spheres for help.

[Philip Shounev]

Hello, mathieu_boch,

Thank you for the report and provided scene. Those artifacts are indeed visible with certain camera angles and normals are actually not required for the issue to occur, only default VRayMtl with mapped bump is sufficient. I've logged it in our internal bug tracker under VMAX-14234 so we can research it further.

[fixeighted]

Very strange. I just checked again and I can't make the problem occur, so it looks as in the attached and at any angle I look at.
This is using Max 24 and latest Vray release.
Maybe someone from Chaos will see this post and choose to respond, as possibly they'll be able to discover what's happening.

EDIT: Philip beat me to it. However, why I can't trigger the problem is strange. I guess I missed the specific angle at which it's triggered.