When I use IK redirection, I always get a prompt saying “Root Motion Remap Op, missing source root bone None.” I have already set up the pelvis. How can I solve this problem?
Hi there!
I think i know what’s happening here. This error message (Root Motion Remap Op, missing source root bone None/missing target root bone) appeared when trying to calculate the root motion transfer, which means either the Root Bone field wasn’t assigned in the IK Rig/Retargeter settings or the Root Motion modifier is misconfigured in the chain’s settings.
The pelvis setup is essential; however, the Retargeter should also have clear information about which one of the bones in the hierarchy is considered the Root (typically, it’s the tip-most bone called root) for both meshes.
I’d suggest trying a couple of quick steps to see if this clears up the log warnings:
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Check the IK Rig Root Bone Settings:
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Open both your Source and Target IK Rig assets.
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In the Hierarchy panel, right-click your top-most root bone (often named Root or Base) and make sure it is assigned or set properly, or check the Retarget Root assignment in the asset options.
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Verify Root Motion Settings in the IK Retargeter:
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Open your IK Retargeter editor.
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In the Asset Details panel on the right, look under the Root Motion / Global Settings section.
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Make sure the Source Root Bone and Target Root Bone fields are pointed to your actual root bones (e.g., root) instead of being left as None.
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Check Retarget Root Chain:
- Make sure your Pelvis bone is assigned as the Retarget Root (right-click Pelvis → Set Retarget Root) in both IK Rigs.
If you still see the warning after checking those, can you share a screenshot of your Target IK Rig settings and how your root bones are set up in the hierarchy?
It will help me narrow down whether it is simply a missing assignment in the chain or an issue with root motion settings!
Here a couple resources and official documentation links about IK Retargeting in Unreal Engine that might be helpful:
Epic Games Documentation: IK Rig Retargeting
Videos:
Unreal Engine 5.4 IK Retargeting Tutorial Easy Animation Retargeting
How to Retarget In Unreal Engine 5.5 | Retargeting Deep Dive
Quick & Easy: Setup a Source Retargeting Rig in Unreal 5
Hope this helps you get it sorted! Let me know how it goes!