Model too small, faces missing ? UE world scale vs maya ?

Development Asset Creation
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1

Hi everyone !

I’m facing very strange problems when importing fbx models in Unreal.

I’ve been trying to transition from Maya/Vray to Maya/Unreal for a little while now.
I’ve been working with a big client since 2019 and they give me some industrial .step files to work with. I do videos explaining how they product work and do all the rendering with Vray inside maya, it’s doing great so far but I really want to cut those render time and transition to Lumen/path tracing inside UE.

I’ve accumulated a bunch of their product that are all ready to use inside of maya and this transition to unreal will need to be the smoothest possible. But right now it’s not.

I’ve been facing a strange problem (and found a solution) but I don’t understand why it does that and if it is possible to bypass it.
My workflow is the following.

  1. Open .step files into Moi3D
  2. Exports the 3D models into fbx with tessellation and TRIANGULATION
  3. Import in maya, clean the model, fill holes and check for overhaul normal issues.
  4. Rig and animate, then render.

My goal is to send those models to Unreal and render there. BUT.
Whenever I import my models into unreal I get missing faces. Litterraly missing faces. No backface culling stuff or not facing right faces. My models are uber clean and work like a charm in maya.

I searched for multiple answer already and one did the trick, but it’s messing with my workflow so much that I might avoid it.
I stumbled upon a post on this forum and the guy was suggesting to increase the scale of the models and see. And it worked. Faces where back up again and fully visible.

But it cant be like that for me. I’m willing to spend time redoing material for my models for all the products but it’s too messy if I have to bake animation of my rigged models and applying a 100+ on the scale axis.

So my questions after all this, is:
• Why does Unreal cant deal with “too small” models ?
• Is there something that could be done to avoid such thing and go on with my transition?
• The scale of the imported models are good in world unit because they are used in CNC machining. How does it doesn’t work well in Unreal unless i force the scale up ?

Thank you for your answer,
Have a good day !

2

Hi, if you are missing small triangles, try deselecting “Remove Degenerates” in the FBX import options.
Make sure the “Advanced” section is expanded, and untick “Remove Degenerates”:
KeepDegenerates

3

Hi,
Thank you for this ! But i don’t see the option available under Mesh>Advanced for Skeletal Mesh FBX Import…

I could actually use it anyway by importing a rigged model with no meshes or lower res one that would be hidden and just import High res static meshes into the bone logic (I assume it’s possible but not tested yet).

I’ll need to try to clean my model even more. Those degenerate faces definitely looks like it’s the problem.

I tried both in 4.27 and 5.1 and the faces problem seems better handled in 5.1 as I see less holes.

So is there a “Remove Degenerate” option equivalent for Skeletal mesh ?

I’ll try doing some deeper cleanup into my models to remove those near overlaping edges and also try the static hi res meshes into the bone structure and animating a proxy low poly model. I’ll keep updating the result.

Thanks !

4

Ok so I think it was after all just a question of model cleaning !

I got into maya and did an extensive cleanup session. Deleting Nonmanifold geometry or lamina faces. Then the Non-planar tris disapeared (which is strange cause tris cant be non-planar).

What I was able to get away with before in maya and vray cant be done in Unreal and my models needs to be the cleanest possible !

Anyway thanks again @splodginald you put me on the right tracks!

Have a good day !