How to add IK and Weapon bones for Metahuman

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Hi everyone,

I’m working with a MetaHuman character and have run into an issue with weapon bone/socket alignment when importing animations created on a different MetaHuman.

My setup

By default, the MetaHuman skeleton does not contain weapon or IK bones. I added the required weapon bones using the Skeletal Mesh Editor in Unreal Engine. I also created a socket on the weapon bone and adjusted its transform so that my sword fits correctly.

For the retargeting settings, I configured:

  • IK bones: Animation

  • Weapon bones: Animation Relative

With this setup, the sword attaches correctly and works as expected with my animations.

The problem

Our animator created an animation using a different MetaHuman character. He was working with a dummy MetaHuman character, and I provided the different DNA file (not the character im using in unreal).

Since the dummy MetaHuman also did not have the weapon or IK bones by default, the animator added those bones in Maya and created the animation.

After receiving the animation, I imported it into Unreal Engine and assigned it to the MetaHuman skeleton that contains my weapon and IK bones.

However, when I play the animation, the sword does not align correctly with the weapon socket. The socket that was previously working correctly with my other animations no longer keeps the sword in the correct position/orientation during this animation.

My questions

  1. Is this happening because of the retargeting settings for the weapon and IK bones?

  2. Does adding the weapon bones in Maya on the animator’s side, instead of adding them in Unreal using the Skeletal Mesh Editor, cause a difference in the resulting animation?

  3. Could the bone hierarchy, bone transforms, or reference pose of the weapon bones be different between the animator’s MetaHuman and mine?

  4. What is the recommended production workflow for adding weapon and IK bones to MetaHumans when animations are being created by different artists?

  5. Should the weapon/IK bones be added to the MetaHuman skeleton in Maya and then used consistently by both the animator and Unreal, rather than adding them separately in Unreal?

  6. Is there anything specific I should check in the Skeleton Retargeting settings or during animation import to make sure these bones retain their correct transforms?

The important point is that the socket itself is correctly positioned and works with other animations. The problem only occurs with the animation created on the other MetaHuman.

Any advice on the correct workflow or what I should check would be greatly appreciated.