Skeleton root bone scale incorrectly set to 1 in animations after "Imported bone transform is different" error, resulting in smaller/bigger meshes in animation

cyaoeu
Wed, 07 Jun 2017 14:03:45 +0000
Character & Animation

The root bone scale in a skeleton is incorrectly set to 1 in animations after you import a skeletal mesh getting a “Imported bone transform is different from original. Please check Output Log to see detail of error”. The error itself is caused by the Blender exporter scaling all of the bones in a rig instead of only the root bone.

Because the root bone scale is set to 1 incorrectly the animations look wrong. If the mesh was scaled 100 times the root bone scale should be 100 in animations too, but in the case of the error it’s set to 1 so the character is 100 times too small in the animations while looking fine in Persona skeleton/mesh mode.

FBX files here:

To see normal scaling behavior:

1. Import blender001scale.fbx with Import Uniform Scale set to 10 and importing animations.

2. The skeleton root bone has 10 scale in the skeleton view.

3. The skeleton root bone has 10 scale in the animation view.

blender001scale.fbx was exported using metric 0.01 unit scale in Blender, which works but causes issues in other parts of Blender.

To see faulty scaling behavior:

1. Import blender1scale.fbx with Import Uniform Scale set to 1 and importing animations.

2. You get an error saying “Imported bone transform is different from original. Please check Output Log to see detail of error” because on export from Blender all bones were scaled instead of just the root bone.

3. The skeleton root bone has 100 scale in the skeleton view.

4. The skeleton root bone has 1 scale in the animation view. This is a bug, it should be set to 100 like in the skeleton view. Because of this the animation is tiny.

blender1scale.fbx was exported using metric 1 unit scale in Blender, which at the moment causes issues with UE4 but works perfectly with other areas of Blender.

9 posts - 7 participants