Metahuman facial animation breaking (deforming) on higher LODs

I am having an issue with playing Metahuman facial animations on anything other than LOD0.
This is an example frame across different LODs:

Has anyone had a similar issue and if so, have you come up with a solution? Is there a way to bake an animation for a specific LOD?

Further information:
The project is 5.1.2, but I’ve converted the project to 5.3.2 and the issue persists.
The animations were captured with LiveLinkFace on an iPhone. Then they were processed with MetahumanAnimator in a different project. They were afterwards exported and imported into the problematic project. The problem does not exist in the project they were processed in. This separation of projects is crucial, as one is supposed to be just for animating, and the other is an actual game. Furthermore, I’ve tried creating a project from scratch, importing a Metahuman, and importing the same animations, and there is no issue with swtiching LODs.

My best guesses:

  1. In the game project, I’ve deleted everything that I thought was unnecessary, including the Metahuman Face Control Rig. Since the animations are baked to a skeleton, I didn’t think this would be a problem, but maybe the control rig does something in the background when switching LODs.
  2. The skeletons in the 2 projects are slightly different, as I get this message when importing an animation:

    This didn’t cause any issues on LOD0, so I didn’t think it would matter, but maybe it causes an issue when recalculating the animation on higher LODs. This wasn’t a problem until recently, but the lowest LOD available for facial animations on Android is LOD3, and I need to make the game more performant on PC anyway.

Do you know anything about anything about working in 3d?

No?
Here’s a 3 line primer, but you should really look into learning that before jumping into complicated stuff:

A mesh is made up of vertex (3 of them make a tris which is rendered in screen).
A morph changes the position of a group of vertex (causes the render tris to move at runtime).
An LOD reduces the amount of vertex (removing rendered tris).

Now… knowing this: make your conclusion.

I hope this is you missinterpreting stuff and not BS that metahumans want to pass on as possible.
It can be possible, if you make LODs manually.
Metahumans are not manual.

Thanks for taking the time to answer, but there was no need to be condescending.

I don’t work with 3d on a daily basis, but I do understand what you wrote, despite maybe not knowing the technical terms.

I expect the animation to not be as pretty on higher LODs, because of the smaller number of triangles and corrective bones in the skeleton. Despite that, I was 100% sure that the deformation that was present in the images I sent was not the intended behaviour.

As for the Android issue, I am not sure as I haven’t found a reliable source, but I am guessing that the Metahuman face mesh is not hard coded to only work on LOD3 and above. Rather, my hunch is that there is some inherent upper limit on the number of triangles in a mesh when developing for Android, or something similar. As you are more experienced with this, If you think that’s not the case, be free to share your insight.

I managed to solve the issue by reimporting the Metahuman. I thought the issue arose due to different engine versions, but it actually came down to Metahuman versions.

As my project was originally in 5.1, the project contained the 5.1 version of the Metahuman, even after I converted the project to 5.3. It was resolved after I converted the Metahuman to 5.3 in Metahuman creator and reimported it.

So it seems to me that Metahuman versions aren’t backward compatible, as the 5.1 Metahuman didn’t properly handle the LODs of an animation that was baked on a 5.3 Metahuman.

No, you could put anything you want in the scene and it will run - just badly.

The tris count is important, but metahumans are not for game development so it doesn’t much matter what you do.
They’ll run like trash on PCs, just as well as android.

They are trying to make it to where people much like yourself can use them, without much or any knowledge of character creation, but they are eons away from anything viable.

The issue with the morphs was more likely to be bad LODs or autogenerated LODs or similar.
Still, i think with the newer version you got some benefits anyway, so thats probably the way to go about it.

You should really learn things and make your own mobile compatible skeleton with a proper LOD reduction if you are hoping to release anything viable.