I have been struggling several days now trying to retarget the IK bones from a custom animation pack that uses the UE4 skeleton.
I am trying to retarget it to a custom character with the proper UE skeleton hierarchy + additional bones.
I have created both IK Rigs with goals and bone chains (taking the UE4 IK rig from Thirdperson template). So far so good. I can retarget all animations I want with IK Retargeter and the rest of bones work great.
However, IK bones are not correctly placed in the right location.
Facing the same issues. I just migrated my project from 4.27 to 5.1 and after a full week of trial and error, testing different options and watching pretty much all the video online, I never got my IK bones / Virtual Bones to work either … with pretty much the same unfortunate results…
Why is this still an issue? I am having this problem, the retargetter cant even properly retarget UE5 manny to UE5manny (himself) without the same issue. best option I could maybe find is this plugin that forces the IK to snap to bones, but why should I have to pay for something that has been broken in UE5 for almost year now?
I’ll also share the current Fab link to the RM Fix Tool asset mentioned above, just in case.
RM Fix Tool is very helpful in solving certain root motion issues.
Don’t forget to check if the chain mappings for the IK bones are properly mapped in your IK Retargeter asset.
Also, check if the retarget chains for the IK bones are actually set up in both the source and target’s IK Rig assets!
For some reason, it seems Epic removed the retarget chains for the IK bones, in the default IK_Mannequin IK Rig asset.
So, I had to re-add them myself.
Additional notes about my retargeting process:
I’m using Unreal Engine v5.4.4.
In my screenshots, I’m retargeting from the Mannequin (UE5 skeleton) to a VRoid/VRM character (VRM skeleton, imported using the VRM4U plugin).
I used the Free Bone Snapper plugin to snap the VRM skeleton’s IK bones to their proper positions (i.e.: their respective FK bones).
For more details, please refer to Free Bone Snapper’s documentation and video tutorial.
For my specific retargeting setup (UE5 → VRM) to work properly, in the Bone Snapper (solver) settings, I used the following values: Root Snap Bone Name = None In Place = False
In the IK Retargeter, I also used Auto Align -> Align All Bones before retargeting.
You may have noticed the Easy Pose button in my screenshots, it’s from another plugin (by the same developer of Free Bone Snapper) I have installed in my project.
Just ignore this button, I found Auto Align to be a much more reliable option in my case.
For completion’s sake, I’ll share the Chain Mapping settings I used on my UE5 -> VRM IK Retargeter.
On each chain, I’m basically using the default settings, except for the following overrides:
On the Root, FootRootIK, HandRootIK, LeftHandIK, RightHandIK chains, set FK -> Translation Mode to Globally Scaled.
Note: These overrides came from VRM4U’s auto-generated IK Retargeter asset, generated when you import a VRM character to your project.
As these overrides worked correctly for my project, I believe this is a good reference for these settings’ values.
… with pretty much the same unfortunate results…
