Interior Decal artefacts

Hello guys,

would someone be able to explain the below pictured artefacts and maybe offer a solution to fix it?

You’re looking at a wooden cockpit wall (standard material) with two decal materials on top.
One decal holds the nail with albedo, comp and normal texture, the other, underlaying decal is a normals only material that is supposed to add some worn out edges around the nails.
At certain light angles I get this funky shading as seen in the first image.

Things I’ve tried to fix it:

  • ‘Don’t cast shadows’ turned on and off.
  • moved the decals closer/farther away from the base mesh.
  • played with the draw order.
  • added/removed albedo/comp textures from the “normals only” material

The is the “normals only” material

…and this is the nails material:

Is this by chance caused by the same bug that causes light bleed through, for example described here?

Hello @Mathias ,

What do you see when you debug the PBR using the AO map in the game? (Go to devmode > Options > PBR Channel > AO. Documentation here..) Is the AO applied to both your main material and decals?

If yes, we will need a package that reproduces this issue. You will find the instructions to send us your private content in the 3rd section of this post.


Thanks for your reply @Boris !
AO is definitely clean in the debug view, the decals use the same AO as the base mesh.
What exactly do you need from me, the Max file or the package source folders?

Package files are provided. If you also need the MAX file please let me know.

Hello @Mathias ,

I’ve reviewed the textures of your package and the problem originates from the white squares in the red channel of the nail comp textures.


And in this reference: (there are 16 x 1px border white squares here)

It should be completely black.

Hope it helps,


Thank you very much for looking into it, @Boris!
Unfortunately, making the red channel black on both nails_1 and nails_2 comp textures does not solve the issue, the problem persists.

I checked again the project and you are right we can still see those artefacts.
In fact, by removing the normal map and using the devmode “option” > “PBR Channel” > “Normals (world)” we were able to see that it’s a normal mesh issue:

Our guess is that the decal mesh normals do not match the ones from the wooden plate behind. Double check your normals for both of these to make sure they’re not misaligned.

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Ahhh, interesting! That is it!
Xview didn’t give away any issues with the face normals.
The offender is a “dirty” normals map of the underlaying wood material.
Thanks much for your help, @Boris !


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