What is the Hips_Yposition in pose_features.expmap.txt?

[dongran]

Thank you for providing your great work!

I found that Hips_Yposition is also selected as a motion feature for training.

However, there are already reference_dXposition, reference_dZposition, and reference_dYrotation here, which indicate Hips_Xposition, Hips_Yposition , and Hips_Zposition (I think) because the hip joint is the root joint.

So what is the Hips_Yposition? Or what are the reference_d?positions?

Could you tell me the difference between the reference_d?positions and root positions (hip)?

[simonalexanderson]

Hips_yPosition is the height of the hips above floor level. The reference_d values are translation and rotation deltas between frames (thus corresponding more to velocities) and can be integrated up to get the global position and rotation. The reason for these representations is to get features which are invariant of where the person was located in the capture space.

[dongran]

Thank you for your reply!