Inconsistency between custom body mesh and UE MetaHuman Head normals

[Apury]

Greetings!

I figured I could save myself some time by attaching the MetaHuman’s head to my own body but I can’t seem to figure out how to fix the shading difference which from my testing seems to be related to different directions vertex normals

The only possibe solution I could think of after trying most things from weighted normals to the extensive selection of options in the Alt+N menu is to simply extend a face from the head and use that new face to retopologize the whole body once more, hopefully resulting in the same direction for the normals.

Before diving into that work, I’d be grateful for any advice.

[Okidoki]

Welcome …

if the head is really connected to the body: Object Data → Geometry Data → Clear Custom Split Normals

[Apury]

My apologies for not having clarified the situation better.

The head isn’t and can’t be connected to the body.

The body itself however is also split into different parts which in turn aren’t connected either if that somehow helps.

I however decided to join the head and torso together, merge by distance and Clear Custom Split Normals Data to see if that would unify the shading.

This was the result:

[Okidoki]

Because the different areas and also different topology on the body and on the head and shoulders this will never have the same normals… the are simply not the same and so can’t have the same normals.
I remember an very very old trick when using this overlapping technique… make both parts transparent along the borders…

[SoundDifferent]

You can make a duplicaded base mesh where everything is connected and welded.
For each disconnected part, making a vertex group around the cutting line and use Data Transfer modifier to transfer the normals from welded basemesh.

In case the head and body didnt have the same topology and cannot be welded, you can connect them in ugly way with triangles and so on and put a remesh modifier on top + smooth corrective.

TBH i doesnt deal with characters in Unreal so i cant be sure what custom normals wouldnt be ruined after skinning, bone deformations and so on.

[Okidoki]

Or simply “cut” at the neck and not down at the shoulders so the there should be some circular like shapes to connect via edge bridge ???

Here’s a simplified example using multilpe cuts and a “rounded” profile factor: