Imported FBX meshes have broken UV's. Why is this?

When I import a mesh into Unreal Engine 4 the UV’s on my model do not seem to work. Applying a checker pattern to the model in the game engine shows severe distortion to the UVs. I have also had this issue in Mudbox with distorted UV’s, when creating a diffuse paint layer and the model texture breaks. I’m posting this here in the hopes someone might know what the issue is.

My model is very simple and I can’t understand why this issue is affecting me. I am very new to unreal but have been working in 3D for years (if this helps). The program I am using is 3Ds Max 2015 (Student Edtion).

My steps:

  1. Model the object (in this case a wooden beam).
  2. Smooth it using the Smooth Modifier.
  3. Collapse the stack.
  4. Apply xForm.
  5. Collapse the stack.
  6. Apply the UV Modifier.
  7. UV model.
  8. Collapse the stack.
  9. Select object.
  10. Export out model using the inbuilt FBX exporter (with the recommened options Epic uses).
  11. Import UV’d model into Unreal.
  12. Observe UV’s have broken.

These are some images showing the issue plus some more for contex.

My model and its UV’s:

My model with a checker pattern on it inside 3Ds Max:

My model with a checker pattern on it inside Unreal:

I think the issue might be to do with Max’s FBX exporter but I seriously don’t understand why. I’m using the recommeded versions (2015 max still exports a 2014 FBX file) and recommended settings. Exporting the object as an OBJ seems to work but I’d rather not use a method that has less control over a final outcome.

Has anyone else had this issue? I really just want to have a smooth transition from max to unreal and at the moment, I can’t get that with FBX.

This issue effects every model I export as an FBX.

Many thanks!

Can you post a screenshot of the UV layout in the static mesh editor please?

Here you go:


Apprently I have two UV channels. I’m going to fix this up, see what happens a second time and reply.

Set all my polygons to a UV ID of 1 and the issue still persists. Opening up the second UV channel shows me a neatly ordered new uv of my model (I presume). Not sure what’s going on there, but could that be causing my issues? ← Full precision UV’s set and I’m showing UV channel 1, which is the lightmap one.

The max file and the fbx for you :slight_smile:

Having 2 UV channels is fine. The engine generates lightmap UV’s in channel 2(in engine channel 1) while importing the mesh, and thats what it is. The materials use the first UV channel, which is what you’ve taken the screenshot of, by default so i’m not sure whats up. Enable Use Full Precision UVs in static mesh editor > Details panel > LOD0 and see if that fixes the issue.

Can you upload the mesh so that i can take a look?

Sorry, this is the max file, not the one in the folder!

Edit: I have to head off for a few hours now, so I can’t repsond to any questions I’m afraid. I’m using the newest version of the game engine that the launcher provides btw.

I took a look at the fbx file in Max(and also in UE4) and it looks like the UV’s got somehow messed up during or before export. If you import the fbx into Max and apply a checker texture you’ll see the same issue. When you open the UV editor and select faces they dont line up properly. They look as expected but there are actually overlapping faces.

When you get back and still cant fix it, can you save and upload the Max file as 2014 please?

I had the same thing happen to me, I had a friend try it on his PC and it worked fine for him but another friend had exactly the same issue I had. The work around was to save the file out as a 2014 3ds max file and then open in 2014 and export the fbx out. This fixed the issue.

Not a perfect workaround and is slightly annoying seeing I was using the exact same settings as the person who got it to export correctly.

I fixed the issue. Turns out one issue was sort of my fault and sort of not. I had a light bulb moment earlier when I thought to myself “I’ve imported models just fine before, what’s changed?”. Turns out letting Max’s FBX exporter do the triangulation really screwed something up, causing strange artefacts on the model face. So I switched back to doing it a really easy way before exporting it (convert model to mesh → select the ‘visiable’ option → convert to edit poly). The model after manually triangulating it was fine in UE4.

Thank you to everyone that helped!

TL;DR: Don’t let the exporter triangulate for you! It will screw up!

Thank you very much for your help! I’ve fixed this issue and have written about it in an answer to this thread.

Cool, glad you found out what the problem was!

I had the same problem and I googled it. More people than just UE4 users are experiencing the same thing.
What works is to just put an “Edit Mesh” modifier on top of the stack and export. It works every time for me now.

Ok I was having the same issue as well. Using 3DS Max 2016. Was getting uv channels broken, being deleted, replaced, etc. I tried everything you guys have listed on the forums and it turns out switching the export options from binary to ascii helped.


Thanks a lot! You really helped me/

Sefyra’s solution has the advantage of letting you go back to previous modifiers, as opposed to collapsing everything into a mesh

No. This is a UE4. Not FBX.
I have tried all of the above and none of them work.

The correct solution is to untick Generate Lightmap UVs

Found solution here