billyio/joint_angles_calculate

Calculate the joint angles of a body pose

Calculating Joint Angles

This code calculates the joint angles of a 3D body pose that was output from my other repository: Real time 3D body pose estimation using MediaPipe. If you want to know how the joint angles are calculated, check my blog post here. The joint angles are calculated by defining a T pose and assigning right handed coordinate system at each joint, as shown below.

I've included a sample keypoints file. Simply run the demo as:

python calculate_joint_angles.py kpts_3d.dat

The calculated joint angles are returned as "jointname_angles". We can use the calculated joint angles to put the motion on a standard skeleton. This is useful because keypoints estimators are not consistent with their estimations, which leads to varying bone lengths. In red, we show the original output of Blazepose [link] estimated 3D keypoints. In blue, we show the pose applied on a standard skeleton from the joint angles. The discrepancy between the poses is due to inaccuracy in keypoints estimation leading to bone lengths changing.