"Mesh Normals Invalid" when importing mesh

[Tender5EF6]

Hello! I'm experienced with Maya and other 3d programs but am fairly new to using Substance. I'm encountering an issue I can't seem to find any documentation on: when I import certain meshes into Painter, it tells me:

"Mesh normals are invalid (some values are null) and will be recomputed"

...and then re-calculates the normals itself. My mesh has a lot of custom hard / smoothed edges, and when I bring it into Substance it basically softens all the edges, leaving it looking pretty gross. The mesh looks correct in both Maya and Unity, as well as in Blender. 

Here are some things I've tried, unsuccessfully, to fix this: 

• unlocking the normals in Maya, averaging them, setting them to face, etc. and then re-doing all my custom hard edges and re-exporting to Substance
• exporting as an obj and then re-importing into a fresh Maya scene, and then re-exporting to Substance
• the classic "cube trick" (combine the mesh with a cube, delete the cube faces) 
• resetting fbx export settings and ensuring that normal data is exported properly
• doing a mesh > cleanup to make sure there isn't any nonmanifold geometry
• deleting my maya prefs

Often, after doing one of these troubleshoots, I then get additional error messages in Substance saying that my tangents / bi-normals are invalid, as well.  

The only thing I have tried to fix this successfully was a tip I saw when googling the issue: importing my fbx into Blender and then just re-exporting it from Blender. I have no idea why this works but it seems to magically allow Painter to read the normals properly. It's unfortunately not a permanent fix; if I import the new re-exported fbx in Maya to edit it, and then re-export it from Maya and import it into Painter, it gets messed up all over again. 

Does anyone have any idea what might be going on here, or how to fix this issue? It's happened with two different meshes for me now and is driving me a bit nuts. There are no real similarities between them other than initially being built in the same maya scene. 

I've attached one of the problematic meshes to this post here. Thank you! 

[GeoffroySC]

Hi,

I noticed your mesh is scaled down. Could you try to apply the transform before exporting? 

[Tender5EF6]

Hi! Thanks so much for your reply-- What sort of scale are you seeing on your end? On my end the mesh is not scaled down, just offset a bit from the scene origin.

[Tender5EF6]

Hi Geoffroy-- it's been several weeks but unfortunately I am still encountering this problem with various models and still am not sure why. Is there anyone at Adobe Support who can help me with this issue? Thanks!

[graemeg17883850]

Hello author.

Can I ask, did anyone from Adobe ever provide you with a solution to your original problem?

G.

[GeoffroySC · Accepted solution]

Hi, 

This issue is a modeling one. If you fail to provide Painter with normals, tangents and bi-tangeants ; Painter will recalculate them. This isn't a bug. 

When exporting from any modeling software check the different parameters, you should be able to export those data with the .fbx format.

Kind Regards,

Geoffroy SC 

[graemeg17883850]

Ah, right. Thanks for your response.

G.

[Jonathan25616226hr7z]

I've had this issue come up a couple of times before. In my case, it's often been that I have a vert right on top of another vert with unallocated UV space. For this, I usually just do a merge vertices operation in Maya making sure that the UVs are preserved. This has resolved the issue for me quite reliably.

[Gharrington]

I learned a trick to fix this if you're in Maya. If you select your mesh that's having an issue, select all of the faces and "duplicate face". Delete the original mesh and the new mesh will still have UV's. It might need to have it's shader reassigned. It's the only fix that's seemed to work for me on many occasions.