Maya is destroying vertex normals ?

Peksio · Jan 2019

Hello, I wanted to ask you for your help with vertex normals in maya. This is quite weird for me.

Mesh looks fine in maya. But when I import it into Substance Painter, it looks like this:

Image: https://us.v-cdn.net/5021068/uploads/editor/3q/qn7udb51w1cw.png

I tried making every edge hard, set normals to face, unlock normals in many diffrent ways including various scripts. Still nothing

But when I import this mesh into 3ds max or Bledner, then exportm then import to maya then export one more time into substance painet everything is good. But when I try to do anything with this mesh in maya it is once again wrong

I just run out of ideas. Maybe someone have anything that could help me ? Right now I am willing to try even weirdest ideas :P

Udjani · Jan 2019

It's probably a tanget space problem, blender and painter use mikkt, maya don't, When creating the new project in substance mark the checkbox ''Compute tangent space per framgement.''

More about that here:

https://www.youtube.com/watch?v=gR3r7Xmhmlk

Peksio · Jan 2019

It isn't working

It is not on all of my meshes. From around 9 exported meshes in one fbx, only one mesh is corrupted like that

Peksio · Jan 2019

Ok. I remembered that once time I fixed this problem with splitting all of my polygons of this mesh.

This time ... it didn't work. I kinda get crazy. They are not connected polygons and they still look like everywhere are softedges. But if I move one polygon from mesh, it looks like this:

It is ridicoulus ...

Image: https://us.v-cdn.net/5021068/uploads/editor/08/1phi6mbkef1z.png

sprunghunt · Jan 2019

Peksio said:

Ok. I remembered that once time I fixed this problem with splitting all of my polygons of this mesh.

This time ... it didn't work. I kinda get crazy. They are not connected polygons and they still look like everywhere are softedges. But if I move one polygon from mesh, it looks like this:

It is ridicoulus ...

Try turning on the normal display. In maya select the shape node and scroll down to "mesh component display" and select 'display normal' then set the dropdown underneath that to 'vertex' and increase the normal size value.

Then post a screenshot of the mesh back here.

Peksio · Jan 2019

Thanks for your answer. Here is screenshot:

Image: https://us.v-cdn.net/5021068/uploads/editor/ny/xlglbxe78xtc.png

Quack! · Jan 2019

When you import to Painter, does the Log throw an error saying that the Tangents/Bitangents are broken and it is recalculating?

Peksio · Jan 2019

Yes. I have checked in maya to export smoothing groups, tangents and binormals and I still receive errors:

[Scene 3D] [FBX] : Mesh normals are invalid (some values are null) and will be recomputed

[Scene 3D] [FBX] : Mesh tangents will be recomputed for coherency

[Scene 3D] [FBX] : Mesh bitangents are invalid (some values are null) and will be recomputed

But other meshes in my scene are working fine

sprunghunt · Jan 2019

Peksio said:

Thanks for your answer. Here is screenshot:

The yellow normals are locked normals. I suggest you unlock the normals and see what happens.

Peksio · Jan 2019

Ok, I think that I have a breakthrough. Now I can see that my vertex and face normals are fine. But my tangents are corrupted:

Image: https://us.v-cdn.net/5021068/uploads/editor/h2/m211ov75h8je.png

Is there a way to somehow reset them ? I was googling but I got only tangents from animation

@ Edit: Ok, afterall it isn't it I think ... also unlocking normals are also not working

@ Edit2: If I export this mesh as obj it is fine, but still I need fbx

Quack! · Jan 2019

The issue is caused by many things. The solution is also many different things. What I recommend is running mesh cleanup, only turning on the cleanup options one at a time and choose the “select” option rather than “fix”.

Busted UVs can cause this. Coplanar faces can cause this. Rats nests can cause this. Substance Painter being picky can cause this. I bet substance designer or any other program would load this model jut fine.

Neox · Jan 2019

can you tell blender to export the Smoothinggroups/Hardedges but NOT the normals? You certainly can in max, this way you get the equivalent of Smoothinggroups from Max inside Maya.
Another option would be a script that turns locked normals into hard edges.

Peksio · Jan 2019

Ok guys. I got the solution to it. The answer was ... corrupted low poly model. By corrupted I mean few overlapping edges/faces with 0 space.

It is pretty shocking to me because, I encountered earlier errors with overlapping edges a lot. But it never, never gave me results like that.

I think that it may be because I was running many calculations of vertex normals based on geometry. When script encountered those corrupted faces it went crazy. Still ... it is the first time that this kind of error gave such a result on my mesh.

I want to thanks all of you for your help. And for further generations ... if something weird is happening, check your geometry more than two times :P

DustyShinigami · May 2022

I'm currently experiencing this issue myself. Substance Painter keeps complaining that [Scene 3D] [FBX] : Mesh normals are invalid (some values are null) and will be recomputed. I've gone and unlocked all of the Vertex Normals in Maya for every asset and re-applied Smooth Edges or Smooth/Harden Edges, but it still keeps throwing the error up. Also, baking is taking way more time than usual. Even just processing a Normal map bake.

I've noticed you can check 'Display Tangent' in Maya as well, which is displaying red and blue lines. I'm not sure what they're supposed to look like if they are/aren't corrupted though. Or how you go about fixing them. Also, once the Normals have been unlocked and the smoothing set up, are you supposed to lock them again to prevent another application from messing them up...?

sprunghunt · May 2022

https://polycount.com/discussion/comment/2768749#Comment_2768749

I've also noticed that message about mesh normals. I haven't noticed any actual visual difference in the mesh. So I've just been ignoring it.

Maya is destroying vertex normals ?

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