Skeletal Meshes using the same Skeleton have difference reference poses and additive animation results?

Our project uses a generic biped skeleton that was created in the early phases of the project, and in the meantime we’ve made many skeletal meshes for difference characters that use that skeleton. This has been a great system thus far, but recently I’ve encountered an artifact in the behavior of additive animations. I have two meshes using the same skeleton, but the same animation blueprint applied to those meshes gives different results.

In Persona, the only difference was switching the Mesh. Here’s the entire contents of the AnimBlueprint.

The additive animation settings for “LookingDown” is in Local Space and Base Pose Type, Reference Pose. In this case these animations were created many months apart.

When the main skeleton was created these bones were in a different pose, centered inside the head. Later we moved that bone outside the head mesh, and added a controller to turn this feature on and off for individual animations. The character on the right was created much later and exported with one of these helper features turned on and therefore offset from center, and it was imported with at least one of the two following skeletal mesh import settings on:

  • Update Skeleton Reference Pose
  • Use TOAs Ref Pose

When I realized this was the source of the issue I tried reimporting the Character on the right with these settings off, but it didn’t remove the incorrect offset.

We don’t make much use of Additive animation throughout the project, however I’m not worried that there are other issues with any of our shared skeleton meshes that are using different reference poses. Is this to be expected?

Should we make sure to never enable either of these options if we want to preserve the functionality of the main generic skeleton being used in the game?