Normal Map issue with arnold renderer black border

[julio_campos_alvarez]

Hi 

I created a project in maya with an fbx created in house. We added the normal map and we notice that there are a strange shadow when we render it with arnold.  I have a friend that tried the same with 3Dmax and arnold and got the same issue. So I guees the issue is related with Arnold.

I test the same model with other softwares and renderers. And in all this model and the normal map are working fine.

Here you could se some screenshots about the issue

Thanks

[lee_griggs]

Are the normals locked? Try unlocking them and/or reversing them. If that doesn't work, upload the scene and I will have a look at it.

[julio_campos_alvarez]

Hi Lee,

If I unlock the normals the model changes completely. 

I attach a simple project. If you want to take a look. 

Thanks a lot !!

[lee_griggs]

This looks fine to me.

[julio_campos_alvarez]

you have to put the model in this position 

[jesus_zarzoso]

Hello. This is the exact same issue as this one reported 3 years ago
https://forums.autodesk.com/t5/maya-shading-lighting-and/arnold-rendering-artefacts-on-smooth-lowpol...
The answer in that thread is
"

This is a known issue with low-poly meshes with normal-mapping. There is an internal ticket tracking the issue.

It is due to the normal map redirecting the edge beyond a limit and Arnold returning black as a result of an invalid direction.

The best workaround is to use subdivisions where possible.

"

It looks like no progress has been done to fix it in the last three years, Anyone knows if it's going to be fixed anytime soon?

Thanks!

[jesus_zarzoso]

This issue is unfortunately very easy to replicate. Any mesh using smoothed normals and a normal map (any normal map. even ones with all the normals pointing in the Z direction) will render incorrectly. It is easier to replicate when the mesh has smoothed normals that deviate significantly from the face normals (>15º), but smaller deviations will still show the issue at some camera angles.
This is frustrating because other renderers (renderman, mantra, vray) don't have this issue.
Do any Arnold developers read this forum? In that case, are there any plans to fix this issue?

We'd love to use Arnold but this is a deal-breaker for us.

Here are some screen captures taken in 3D Studio MAX 2025.1 that show the issue clearly

   

[Stephen.Blair]

Would more subdivision fix the issue?

Who is "us"? Adding studio names to the ticket will help us prioritize the ticket. You can DM  me, or open a support case.

[jesus_zarzoso]

Hello Stephen, thanks for your reply,

Subdividing the geometry helps to hide the issue, but it doesn't fix it. You can still see the issue when zooming in close enough, at some camera angles.

With "us" I mean our conpany VRBN Studios.

I can provide some extra examples that show the issue, if you want,

Thanks!