Saving DNA for MetaHuman Creator in Unreal Engine
The DNA file saved at any point while working in Expression Editor can be imported back into MetaHuman Creator in Unreal Engine. This will enable you to run any of the assembly pipelines to create a MetaHuman assembly for either Unreal Engine or UEFN.
Using the DNA file modified in Expression Editor:
In MetaHuman Creator in Unreal Engine, navigate to the Head tools.
From the Conform controls, select Import DNA.
Select the DNA file to be imported. This should be the head DNA file saved at any stage of using Expression Editor.
Ensure Import Whole Rig is enabled.
Click Import.
With Import Whole Rig enabled, the character can not be edited using the Head tools. If you remove the rig or create a new full or joints-only rig, any modifications made in Expression Editor will be lost.
Exporting FBX and DNA for Unreal Engine
You can export an FBX and DNA file from Expression Editor to use directly in Unreal Engine, outside of MetaHuman Creator.
This provides the option to export either of two orientations, Y-up or Z-up (the default). Both vertex positions and the axis label in the metadata are affected by this setting.
You will also need to select a body file. This should either be the DNA file for the body (as created by MetaHuman Creator when using the DCC Export assembly pipeline) or a compatible Maya ASCII (.ma) file (such as that created by the Character Assembly tool).
The FBX file contains a version of meshes and skeleton (inclusive of the Vertex Color map required for tangent updates) in the chosen up axis. The DNA file is compatible for use by RigLogic in Unreal Engine, re-oriented to a different coordinate system (handedness and upness different from Maya.)
The DNA file created during export is not compatible with Expression Editor or MetaHuman Creator in Unreal Engine. If using this workflow, you will need to retain both the original DNA file saved during the normal Expression Editor operation, and the one exported here.
Using FBX and DNA in Unreal Engine
The exported FBX and DNA file can be imported into Unreal Engine. The most current and best resource on moving assets from Maya to Unreal Engine is our talk at UnrealFest. The talk shows how to import an updated MetaHuman into the Unreal Engine Editor.
Importing the FBX file into Unreal Engine has some specifics that need to be considered. There is a common issue experienced with MetaHumans where shadows on the face can appear strange; this is particularly noticeable around the eyes. This is related to tangent updating, or lack thereof. Metahumans are supposed to have a vertex color map set to green to control that behavior. Expression Editor will export the map, but it’s also necessary to ensure it’s imported and accounted for during deformation.
During our talk at Unreal Fest in 2023 this is mentioned and exemplified at 26:33. We’ll also indicate the steps here for reference:
When importing the FBX file configure import as in the following two screenshots, of particular importance is the Normal Import Method.
After import the SkeletalMesh needs to be set up so that tangents are updated on frame updates.
In the same SkeletalMesh Skin Cache Usage must also be enabled:
In the Project Settings ensure Skinning is set up as follows:
Next Up
Editing Recommendations
Recommendations for human-looking characters.