Extracting SMPL pose parameters from 3d joint locations

[chaurasiavikash]

Hi everyone,

I’m exploring whether it’s possible to derive pose parameters directly from the 3D joint locations in the SMPL model.

For example, given the joint locations of joint 0 (root) and joint 1 (hip), I expected that it should be possible to compute the rotation matrix for joint 1 relative to joint 0, and from there, obtain the axis-angle representation, which corresponds to the pose parameter.

However, when I attempt this approach, I am unable to recover the correct pose parameters. Has anyone successfully implemented this, or is there a key step I might be missing?

Any insights or guidance would be greatly appreciated!

Thanks!