Serious problem with skeletal mesh imported from Blender

[anonymous_user_b6853a0a]

I’m experiencing a weird issue using a skeletal mesh in Unreal that was created and exported (as FBX) using Blender. This is what the mesh looks like in Blender (with and without skeleton showing):

After importing, a spike shape explodes from the back left foot of the mesh:

The problem appeared to be related to a particular vertex centered on the bottom of the foot. The issue was fixed when I removed the centered vertex and auto-filled the foot bottom instead. This is what the polygons originally looked like on the bottom of the foot, and what they look like now after being changed:

However after fixing the foot, there is now a spike protruding from the tip of the tail when I import the new mesh:

Removing all but the first tail bone connecting to the hip will fix the problem with the tail. After playing around with it for a while and rebuilding a lot of the vertices, the spike will end up protruding from various locations on the mesh (including the front foot).

The mesh is fine if I import it without the armature. So far, I’ve found that taking these steps appears to fix the mesh issue (none of them will actually work as a solution):

-Importing as a static mesh without the skeleton.

-Removing most of the bones bones of the affected limb/tail.

-Removing the centered vertex fixed the issue on the feet. However I was not able to find a single problem vertex when the issue happened on the tail.

-Importing the same exact FBX file into a different engine (Unity) has NO problems at all and works perfectly.

-Importing other humanoid type skeletal meshes created in blender with the same settings does not replicate the problem.

Here are my Blender export settings along with my Unreal import settings:

We have tried changing all of the available import/export settings with no success. Does anybody have suggestions or ideas about what might be causing this to happen? It’s really holding up our project at that point, so any help would be greatly appreciated.

[anonymous_user_389e656c]

Are you applying an animation to the mesh or the spike is visible also when not animated?

[anonymous_user_b6853a0a]

The problem happens and the spike is visible whether or not I apply an animation to the mesh. I’ve also tried importing the mesh without any animations and it still happens. When an animation is applied, the spike moves with the animation as though it were part of the tail mesh.

[TwistedRaven]

I fixed the problem a few days ago.

Check the weight paint of the affected area, or if there is a bone like an IK doing it.

[0vr]

I’m having this same problem, only I’m coming from Maya. The first thing I did was check the weights. It’s not a weight issue because as soon as you get rid of that vertex (i deleted it and the polygons it was a part of) the same problem occurs elsewhere on the mesh where it wasn’t happening before. And I don’t have any IK on it. The problem isn’t even there in Maya, only in UE4.

[0vr]

I’m having this same problem, only I’m coming from Maya. The first thing I did was check the weights. It’s not a weight issue because as soon as you get rid of that vertex (i deleted it and the polygons it was a part of) the same problem occurs elsewhere on the mesh where it wasn’t happening before. Exporting with Split per-vertex normals at least makes the vertex go where it’s supposed to until partway through the animation when it snaps outwards again- this time a different vertex snapping out.

[0vr]

This is really infuriating. Hope someone’s looking into this…

[anonymous_user_bcdd396d]

This problem occurs when a vertex or vertices have no assigned weight at all. This commonly occurs when you are editing skin weights and notice that the influence is present, for instance, on another limb and you paint with the value of 0 remove the influence from the original limb but then do not replace the removed influence with that of the correct limb.

Then, when imported into UE4, the engine has no idea what is how to handle this particular vertex and so it is assigned some random point. Deleting the vertex or vertices will not resolve the issue because the computer program does not possess human logic to just assign the influence to the remaining vertices. When you delete vertices you have completely disrupted the computer’s “understanding” of how the influence is distributed. In other words, if you alter the mesh itself, best to detach the skin and start all over.

I have had this happen numerous times exporting from Maya so before doing anything else, troubleshooting-wise, make sure you have painted that specific vertex on the mesh -and do not alter the mesh without rebinding the skin and repainting the weights from scratch.

[0vr]

I did what you suggested. It imports fine now and plays the animation perfectly. But then I apply a material and the mesh jumps. Parts jump out of other parts. Any idea why? Is this the same issue? I bound the skin 2 more times. I’m about to just write off this animation entirely. But I’d like to know for the future so this doesn’t happen again.
Edit: nevermind. I’m an idiot. Don’t apply your height map to “world position offset”, kids. Bad things happen. haha Well I’m glad this is finally done with. Phew.