Importing an FBX gives me crazy collision and flickering meshes

The mesh in question was being scaled to meters (so *100.0 on export), but UE4 has some problems with things at that scale, so I dropped it back down to no scale, and just decided to deal. In this case, the mesh is approximately 200uu long.

NOTE: When it was scaled up, everything worked.

So, I downsized it, re-exported and imported. The mesh flickered, and would vanish if you looked away. Using F to frame would cause it to go to the very center of the mesh. So, a bounds problem, as the other problems reported like this are.

Perspective makes it hard to tell, but the selected ship is small, and the capsule is the size that the ship USED to be (100x bigger), and not centered on the ship at all (it appears to be at the origin). The ship isn’t a blueprint or a pawn, it’s just a skeletal mesh dragged in to the scene.

There’s no giant capsule that I can see when I open up the mesh in the skeletal mesh editor, although it flickers in there as well. The Maya file has no capsule anyway, I’m not sure where that capsule is even coming from. I’ve never used a capsule for this.

The Pawn that uses this model has its collision set in the class (a box), and it’s correct. However, the ship flickers in the pawn as well.

The capsule doesn’t move when you move the ship, although it disappears if you move the ship out of view.

Anyway, something is seriously messed up here, and the editor is not giving me the tools to diagnose what it is. I am probably going to have to end up cutting and pasting my model into another Maya file and hoping that fixes it.


After a bit more screwing around I figured out a bit more. It’s the physics asset that’s messed up. If I let it make a body for the root bone of the ship, the mass of that body is 1.8million kg. This is for a ship that’s approximately 200x45x25.

The capsule it creates can be moved, but it’s origin is well off the origin of the physics asset creator tool thing. When you move it, it doesn’t actually move like you’d expect either. In short, it’s well messed up.

I’m sure this is Maya generating bad data, but UE4 is choking hard on it and not letting me fix it. I am probably going to have to redo this (placeholder) model in order to get this to work again.

Hi Backov,

Thank you for your detailed description of the issue. Are you still experiencing this problem? What version of the Engine are you using?


Yes, it’s reproducible. However, I work around it. I do still have assets that reproduce the problem.

The engine is a fork of 4.6. No changes anywhere near the FBX code or anything to do with physics or geometry.

Hi Backov,

I was able to reproduce your issue and have entered the following bug report: JIRA [UE-9924]. Should this issue be addressed in a future build of the engine, an update will be added to this post.

Thanks for your help in improving the engine.

It sounds like you are importing this as a skeletal mesh, does it still happen if you import it as a StaticMesh?

I fixed this bug myself. See my pull request. :slight_smile:

Ori Cohen did the integration.