Exporting bones to fbx with animated scale distorts transformations #52039

Closed
opened 2017-07-12 21:44:48 +02:00 by Nahuel Belich · 8 comments

System Information
Win 7 x64
Ubuntu x64

Blender Version
Broken: 794311c 457596d
Worked:

Short description of error

If the bones(even unparented) have some scale animation when are exported to fbx, the transformation of the bones are distorted respect the original armature.
image.png

Exact steps for others to reproduce the error

Export bones with animated scale.blend
1 - Select the original scene chain, (it has all transformations bake)
2- Export as fbx
3- import the fbx

**System Information** Win 7 x64 Ubuntu x64 **Blender Version** Broken: 794311c 457596d Worked: **Short description of error** If the bones(even unparented) have some scale animation when are exported to fbx, the transformation of the bones are distorted respect the original armature. ![image.png](https://archive.blender.org/developer/F660443/image.png) **Exact steps for others to reproduce the error** [Export bones with animated scale.blend](https://archive.blender.org/developer/F660403/Export_bones_with__animated_scale.blend) 1 - Select the original scene chain, (it has all transformations bake) 2- Export as fbx 3- import the fbx
Author

Changed status to: 'Open'

Changed status to: 'Open'
Author

Added subscriber: @NahuelBelich

Added subscriber: @NahuelBelich

Added subscriber: @EugenioPignataro

Added subscriber: @EugenioPignataro

Yes, the problem appear only when the bones have animated scale.

I can make a video demo if you want it.

Yes, the problem appear only when the bones have animated scale. I can make a video demo if you want it.

Added subscriber: @mont29

Added subscriber: @mont29
Bastien Montagne self-assigned this 2017-07-19 11:06:01 +02:00

Weird, as if scale was applied more than once…

Weird, as if scale was applied more than once…

Changed status from 'Open' to: 'Archived'

Changed status from 'Open' to: 'Archived'

That’s actually sort of a limitation of the format… thing is, when you export an armature not binded to any mesh, we do not have any bind data in FBX file - and bind data are closest thing we have to 'rest pose' of the armature, i.e. state in which bones are assumed to be by default. So when we re-import such FBX, we only have the current pose of the bone at save time to rebuild the armature - which leads to deformed (too or too short) ones. Then animation is applied on top of it, which was saved for actual rest pose…

Not sure we can do much here really, only way I can think to work around it is to bind the armature to a dummy mesh for the export, and get rid of that one after importing the BFX…

That’s actually sort of a limitation of the format… thing is, when you export an armature not binded to any mesh, we do not have any bind data in FBX file - and bind data are closest thing we have to 'rest pose' of the armature, i.e. state in which bones are assumed to be by default. So when we re-import such FBX, we only have the current pose of the bone at save time to rebuild the armature - which leads to deformed (too or too short) ones. Then animation is applied on top of it, which was saved for actual rest pose… Not sure we can do much here really, only way I can think to work around it is to bind the armature to a dummy mesh for the export, and get rid of that one after importing the BFX…
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Reference: blender/blender-addons#52039
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