Help with normal map shading issue

Chronicle

Hello, I just recently got a model imported into substance painter and i'm having issues with the shading on the model.  I'm new to substance painter so i'm not sure if its an issue with importing or if its an issue with the export from maya.

When i apply the normal map to the low poly in maya it looks like  
which is totally acceptable.  When I apply the normal map to the low poly in substance painter it look like  
which has some weird shading over the eye and in other places as well.

I had to export the model from maya as an obj despite normally exporting as fbx's.  An obj was the only thing i could get to import and work in substance painter.  First i tried fbx, then i tried maya's dae_fbx, and finally i resorted to an obj.  Would this be an issue with the settings on the export? is it an issue with a setting within substance?  Something else all together?  Any help would be appreciated. I can give more information in needed.

Jerc

Where di you bake your normal map? It may have been baked with a different tangent basis than Painter (mikkt), causing these artefacts.
For your FBX issue, make sure you use FBX 2015 or older format. Substance Painter doesn't support FBX 2016 yet.

Chronicle

I baked it all using xNormal as seperate pieces and then combined them in photoshop.  For the fbx 2015.  How do I export as a 2015 in maya 2016?  I didn't see a setting to make sure it was a previous fbx version.

Chronicle

@Jerc i just figured out how to do a fbx 2015 export so I'm using that version instead of the obj.  That did not get rid of the shading errors so i'm assuming it has to do with the normal map in some fashion.  Normal maps were all done in xNormal and composited in photoshop.

musashidan

Post your normal map if you can.

Chronicle

@musashidan

its not perfect but generally it was working correctly when i was looking at it in maya.

Froyok

Be sure to triangulate your mesh before exporting it out of Maya. Otherwise Substance Painter will triangulate it differently.

Chronicle

@Froyok That did it! thank you so much Froyok.  Triangulating before importing was the key.

musashidan

Just to elaborate on what @Froyok told you, the reason for triangulation is because a tangent NM stores RGB values directly in the vertex data of your normal vectors. It isn't like any other texture map. Even the turning of a single edge after baking will disrupt the RGB values that determine the shading. Automatic triangulation is going to be different between software so the topology needs to be 'baked' to your mesh to prevent this re-triangulation.

Chronicle

ahhh okay.  that makes sense, I hadn't thought about how triangulation effects the normal map.  I had noticed that the triangulation was weird too but it didn't occur to me to triangulate before importing.  I'm still a little new to the whole process.  thanks everyone for the help and information.