I’m literally just spitballing right now but could we calibrate t-pose so we know straight-leg length and then use IK from foot-hip positions to calculate what hip rotation would be based on some standard pelvis width?
I’m not familiar with how kinect tracking works so I don’t know if locking limb length like that is feasible or if rotations/positions are even reliable when not facing the sensors dead-on (but hopefully multi-sensor support is soon?) so it may be more frustrating than just using head rotation at the end of the day