Newbie questions on animation retargeting.

Unity’s retargeting system allows the users to share one animation asset between different Humanoid models, as long as their bones can be mapped onto a humanoid “Avatar”, regardless of how the bones are named. I’m wondering if it’s possible to do the same with UE.

From what I have read and watched so far, it seems it either requires the skeletons to not only have the same hierarchy, but also the same names for the bones (the animation asset can actually be shared this way); or one has to set up a rig and create a NEW retargeted animation asset.

Also, can some one explain the Retarget Source in the Retarget Manager. From the docs, it seem it’s only useful in the first case of retargeting that I just mentioned (sharing an animation asset between similarly structured and named skeletons)? Am I right?

So if you have a collection of animations that use a certain rig, and you have a different rig, then:

  1. if the hierarchies match for both rigs, all you need to do is make a retargeted animation from the original. Right-click the animation asset and you have the option at the top (retarget anim assets > duplicate anim assets and retarget)
  2. if the hierarchies are different between rigs (or if the bone names are different), then the retarget manager is used to manually hook up the bones of your rig to the one its retargeting.

Now, if you already have a rig that matches, you should be able to use the animations without any retargeting. However, sometimes Unreal won’t recognize this, but you can find the skeleton that uses the animations (for example, the UE4 skeleton), right-click it and choose Retarget to Another Skeleton, the tool tip says it will link your skeleton to this UE4 skeleton so it can use the animations that work for the UE4 skeleton.

Unity uses Avatar as an in-between system so that anything plugged into Avatar can use animations that are also compatible. For Unreal, I feel it’s most common to consider the UE4 skeleton as the “in-between” since most animations from the marketplace use it and asset places like Mixamo or Daz3D are similar enough to be considered compatible, if not built for it.

Thanks for your reply, but I think it’s still not made clear to me: so I have to duplicate and retarget, resulting in a full new animation asset, if the bone names are different. There’s no way around it, right?

Because there are different bones, the animation asset needs to be duplicated, yes.

Thanks a lot! Now I’m just wondering why Unreal made it this way. I thought the whole point of retargeting was to share animations. In the end I still have to create separate animation assets for a different model.

If you retarget your skeleton to the one that the animations are based on, you won’t have to, iirc.

I’m confused again. Do you mean if and only if the skeletons have the same hierarchy and bone names? Is it still possible otherwise?