.fbx import: lots of blendshapes get twitchy?

Hi All,
I’m using UE4 to render a short animated film. My main character will use several types of deformations from Maya 2011 so I decided to export her as .fbx into UE4 using animated blendshapes, as vertex animation is on the roadmap but not yet supported IIRC.

To clarify, in Maya, for each frame of animation I bake all my character’s geometry down to a single blendshape. I wind up with a big fat blendshape node that has one shape / frame.

I export this geo from Maya 2011 as FBX 2013 and import into UE4 4.3.0 as a skeletal mesh and it all works fine except:

At longer frame ranges, the mesh starts to get “twitchy” towards the end of the animation. That is, during the last 10% of a longer clip (like 160-200 frames) certain parts of the mesh will jump around, like some small random values are getting added to individual vertices.

Am I doing something wrong here? Is there a set length for this type of animation import?

I’ve been testing this with a variety of models. I see the twitch in some cases and not in others but I can’t consistently reproduce it. I’m going to keep working and if I can produce a better example I’ll post this question again.

Hi CStewart,

I’ve gone ahead and moved your comment to an answer. I’ve also assigned myself this issue so that if you get a consistent repro I’d be willing to test it out and see if I can replicate on my end to submit for this to be looked into by the developers.

If you get a repro for this feel free to post and I’ll take a look as soon as I can.

Thank you!

Tim

OK, I’ve been working on my character for the past two months, trying to improve the import from .fbx into UE4. I have reduced the overall polycount for the mesh, retopologized most of her body and simplified her export from Maya to fox.

Unfortunately, not only does the imported .fbx still twitch toward the end of the animation, now I’m getting random vertices that stay at their original positions as the model moves through it’s animation.

I’ve tried exporting different animations with the same model am am getting consistently artifacting results in UE4.

I’ve uploaded an example .fbx to Dropbox:
https://www.dropbox.com/s/ly70dlx8jbfvg2m/perdita_25b.fbx.zip?dl=0

I’ve imported the above .fbx into two different versions of Maya 2011 and FBX Converter, it plays correctly in those apps. It just seems to get bugged going into UE4.

I’ve also attached two screenies, one shows the import settings I used and the other shows my bugged mesh inside the mesh viewer.

Hi,

I’m having a bit of trouble with the FBX you’ve provided. I import the mesh into 4.4.3, but some things have changed with morph targets since 4.5’s release that doesn’t allow me to import it without the skeleton.

I also, cannot import the FBX into 3Ds Max without it crashing (possibly you’re using a new FBX exporter like FBX 2014?) Would you mind providing an FBX with the skeleton and exported as FBX 2013? If you’re willing to provide the asset with the skeleton you can send it via private message on the Forums with a download link or via email to me.

In 4.4.3 since it doesn’t have the skeleton I cannot see the animation other than going through the individual morphs. Most seem to work well until about 50 or so.

Tim

Tim, I’ve sent you a PM via the forums.

Hi CStewart, I’ve not gotten anything via the forums yet. I’ll send you an email you can reply with the link.

Thank you!

Tim

turn off check topology befor you make the blendshape