I need to develop an application where a user (physiotherapist) will perform a movement in front of the Kinect, I'll write the data movement in the database and then the patient will try to imitate this motion. The system will calculate the similarity between the movement recorded and executed.

My first idea is, during recording (each 5 second, by example), to store the position (x, y, z) of the points and then compare them in the execution time(by patient).

I know that this approach is too simple, because I imagine that in people of different sizes the skeleton is recognized differently, so the comparison is not reliable.

My question is about the best way to compare a saved motion with a movement executed (on the fly).

PS: Sorry by my English.