Wrong wrist orientation - Blender BVH import

[DavidC]

Hello,

I am having a problem importing a hand-only motion capture into Blender. All the finger motions import correctly, but the axis of rotation for the hand bone (from the wrist pivot) is incorrect. Can anyone help?

I am using the BVH >> Motion Builder / Human IK export setting from Brekel Hands v1.37 with "Include Body" unchecked. Imagine a motion where fingers tap on a desk (so the fingers go up and down). This works correctly. Now imagine that the wrist pivots up and down to raise and lower all the fingers together. This results in correct motion within the Brekel Hands interface, but when exported to Blender, delivers a left/right twist at the wrist, rather than up down. The fingers are correct though, so it is only the animation orientation of the hand bone that seems wrong.

I have tried other export settings, but the other BVH export options do not allow exports without the full body, and these do not include any wrist pivot animation. Unfortunately, Blender does not appear to support FBX armature imports. I have tried various methods and conversions, but at best end up with armatures with every bone in the wrong orientation.

Any advice would be gratefully received. 

DC

[Malte]

since you did not mention it,... did you try the axis settings ?

(right hand side..  axis settings)

[DavidC]

Yes  - but there is also a message on that panel that they don't work with the BVH format. So they didn't provide a solution :-(
Thanks for the suggestion though.

DC

[Brekel]

The 20 year old (and very limited) BVH file format simply does not support such things.

You'll need the much more mature FBX file format for storing information like that.

Unfortunately Blender's native support is notoriously bad and unusable (since they develop it themselves instead of using the official SDK that everyone else in the industry uses.).

I believe there is a plugin made by a user that uses the official FBX SDK for Blender somewhere. (sorry don't have a link as I don't use Blender myself)

[DavidC]

Hello,

Thanks for the response. The other FBX importer for Blender also struggles with armatures, unfortunately.

The BVH file format is indeed simple but it does have everything needed for this. It holds hierarchy, angle and offset information for each bone. Your current export correctly saves the hierarchy, offsets and angles for each finger, but not for the hand which parents them. In hand only export, the saved angles for the hand are wrong and in full body export, they are not saved at all. Obviously the hand-angle is fundamental as without it, all the fingers are out of place.

DC