XN_SKEL_HEAD: 1
XN_SKEL_NECK: 2
XN_SKEL_TORSO: 3
XN_SKEL_LEFT_SHOULDER: 6
XN_SKEL_LEFT_ELBOW: 7
XN_SKEL_LEFT_HAND: 9
XN_SKEL_RIGHT_SHOULDER: 12
XN_SKEL_RIGHT_ELBOW: 13
XN_SKEL_RIGHT_HAND: 15
XN_SKEL_LEFT_HIP: 17
XN_SKEL_LEFT_KNEE: 18
XN_SKEL_LEFT_FOOT: 20
XN_SKEL_RIGHT_HIP: 21
XN_SKEL_RIGHT_KNEE: 22
XN_SKEL_RIGHT_FOOT: 24
