Hello,
I’m encountering an issue when assembling a MetaHuman using the MetaHuman Creator plugin (Launcher v5.6.0): the skin tone around UV seams appears uneven only on the exported skeletal mesh.
- Assembled directly from the default template in the MetaHuman Creator plugin
- The issue reproduces when r.AllowStaticLighting=False
- The default setting in DefaultEngine.ini of a Launcher-generated sample project is False
- In Epic’s provided MetaHuman sample project, this setting is absent, so the engine default (True) applies and no issue occurs
According to the official documentation, disabling static lighting causes Material AO to be handled by Lumen GI, which can offer some performance benefits:
https://dev.epicgames.com/documentation/en\-us/unreal\-engine/lumen\-global\-illumination\-and\-reflections\-in\-unreal\-engine\#disabling\-static\-lighting\-for\-the\-project
Could you clarify:
- For MetaHuman projects, is r.AllowStaticLighting=True the intended configuration? If so, does this mean we must forgo Lumen’s benefits?
- If we need to keep r.AllowStaticLighting=False, is there any way to correct the skin-tone discrepancy around UV seams?
For accurate issue reproduction, I have also attached a sample project.
Thank you for your assistance.
Hello,
I’ve spoken to the look dev team and believe it is potentially a problem with AO map discontinuity. However we’ll need to reproduce this locally to investigate further.
Mark.
Hello Mark,
Thank you for the insight regarding the potential AO map discontinuity.
Please feel free to let me know if you need any additional information or logs during your testing. I’ll provide them as quickly as possible.
Thank you.
Thank you for your patience.
This appears to be due to the Bent Normal contribution not being correctly set.
In the material function MF_skin_bentNormals_AO could you change the constant Float3 from (0.5, 0.5, 1.0) to (0.0, 0.0, 1.0) and see if that addresses the issue?
Hi Mark,
I followed your suggestion and changed the Float3 value in the MF_skin_bentNormals_AO material function from (0.5, 0.5, 1.0) to (0.0, 0.0, 1.0).
This resolved the tonal variation near the UV seam, but it introduced a new issue where the tone difference between the Head and Body meshes became more noticeable.
Upon further investigation, I found that the default materials generated by MetaHuman Creator have Bent Normal enabled for the Head, but disabled for the Body. It also seems that no Bent Normal texture is generated for the Body by default.
When I disabled Bent Normal on both the Head and Body materials, the tonal mismatch was significantly reduced.
I have a couple of questions regarding this behavior:
- Is it intentional that MetaHuman Creator does not generate or support a Bent Normal texture for the Body?
- If so, would the recommended workflow be to export the MetaHuman meshes to a DCC tool and generate custom Bent Normal textures for the Body and Cloth? And is there any plan to support this natively in the future?
Thanks again for your guidance.
Best regards,
Seunghwan Lee
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Hi Seunghwan,
I am sorry to hear that this has only partially fixed the problem and introduced a new issue.
As this is not my area of expertise, I’ve shared the updated information with the lookdev team to help understand the problem further.
Mark.
Hi,
We currently do not provide a Bent Normal for the body to avoid the cost of an additional texture - we’ve found that most characters (although certainly not all) are used clothed, and where only the upper neck and hands are visible which therefore hides this problem.
A workaround might be to use a ramp to fade out the Bent Normal map from the head to be flat (0, 0, 1) around the neck area. Otherwise yes, it is necessary to create your own, outside of the MetaHuman Creator workflow.
It is an area that we hope to improve in the future, however at the moment I am not able to share any specific timeline for this.
Thanks,
Mark.