Download

Exporting animations from UE4 to Blender loses root bone

I’m trying to export the couchknights character animations to Blender and make a tweak, then reimport them.

There is no root bone in the exported fbx when imported into blender, and then when reexporting from blender I can see it stays this way instead in ue4, not root bone, so they cant be applied to the existing couchknights skeletal mesh. If i export and reimport the skeletal mesh i can then apply my exported/imported skeletal animation, because the newly reimported skeletal mesh will also be missing the root bone! How do I keep this root bone from being lost?

I see in the Epic twitch stream blender tutorial that the FBXs they provide have the root bone added in. If you export that same hero character or animations to FBX from the engine and open in blender they have a different hierarchy than do the FBX files provided with the tutorial. So it seems he modfied those fbx files somehow or they were the originals before any import into uer. The only real difference is in it and the exported from ue4 one is opened in blender there is an extra root bone at the heirachy that rigidly controls translation rotation and scale of all other bones, e.g. the normal root bone needed for root motion.

I’ve tried exporting the animations and meshes from the content examples animation map root motion demo, and I see in blender the root motion still happens, but is just applied to the entire armature instead of a root bone, the hierarchy is still missing the root bone.

I just want to export the couch knights animations, make some tweaks and reimport. I’m using all the settings from the twitch tutorial and everything works fine except for this missing bone issue. I can even export and reimport the skeletal mesh and it will be missing the bone and then the reimported animations will cleanly apply to that. But I’d rather not do that, as then I have to manually export and import all the animations and rewire them in persona state machines, etc. And I would lose the root bone, if I ever wanted to add animations with root motion I’d have to redo everything.

Any solution to this? On the blender or ue4 side? I’d be fine with manually adding a root bone to the animations in Blender, but don’t know how to properly do that. Everything I google is about blender exports having too many roots, that’s not my issue, I’m specifically talking about the root bone that everything else is offset from, my bone hierarchy does have a single root, but it is the hips, not this special offset bone that is present on the twitch example fbx files and visible in persona on the default skeletal meshes.

If I export and reimport the character skeletal mesh I can compare to the base skeletal mesh in persona and see that the only difference in the skeleton hierarchy is the missing root bone.

I’m on blender 4.73a but I also tried 4.72 and 4.73. I’m using binary fbx export, using the settings from the twitch tutorial, everything works except this missing root bone.

Name the root bone “Root”, try to export with 6.1 ASCII. Try to export the mesh and animations separately.