Import character to UE / Problem with normals

[Kosta]

Hello, dear riggers,

Maya 2024
Unreal 5.32
mGear 4.20 (it is not up to him, so the version is irrelevant)

Has anyone had a similar experience where a blink causes a problem with normals on the lid’s geometry?
The jaw, when it is highly displaced, geometry also turns black…
All other deformations in geometry, such as arms, legs, and spine, do not disturb the object’s normals.

The geometry is completely clean and regular, with a soft edge.
I tried changing the “normal import method” in Unreal, but nothing changed.

I appreciate any help you can provide.

[chrislesage]

I forget what the exact setting is. But in your SkeletalMesh, filter search for a setting about “normal” or “calculate” or “morph”. And make sure the normals are calculated. Otherwise they just stay pointing in the same direction when your morph targets fire.

This screenshot shows the setting you tried. But there is a setting with “calculate” or “recalculate” or something like that. So I don’t think it’s the “import” setting, but something about calculating when it deforms. It might be that “Compute Weighted Normals” checkbox.

[Kosta]

Yes, I tried all the options below for the Normal Import Method.
I tried everything I could find that is called “normal,” the only thing I haven’t tried is resetting the computer

[chrislesage]

It’s not the “import” part. It’s the “compute” part. Did you check that checkbox?

I don’t know which of these checkboxes are specifically related to that. I’m searching for my old notes on the topic. (This screenshot is from 5.1, so it might be a bit different.)

[Kosta]

I tried the Normal Import Method and all other options after import.

[Milio]

mmmm, i think it might be related to this:

Unreal Engine: What Does "Compute Skin Cache" Do? — Mason Stevenson - Tech Art

Unreal by default doesnt recompute normals for skinned geometries, just uses the ones from binding. To recompute the normals, like when character blinks, you need to activate the skincache in the engine.

[Kosta]

Thank you @Milio and @chrislesage

I put this command in cmd inside the character, and it worked!
r.SkinCache.RecomputeTangents 1

My next task is to see how to set up so that every next import is set correctly…

[chrislesage]

Nice!

So I think my issue was different, and was caused by not calculating the normals on morph targets. The skin was fine, but the morph targets were not computing the normals. And that was solved with one of those simple checkboxes.

[Kosta]

I should also keep that in mind!
Thank you!