1. A method of tracking a human target, the method comprising: representing the human target with a machine-readable model configured for adjustment into a plurality of different poses, the machine-readable model including a plurality of joints, including one or more magnetism joints, each joint having a three-dimensional world space position; receiving an observed depth image of the human target from a source, the observed depth image including a plurality of observed pixels; assigning a magnetism body part to one or more of the plurality of observed pixels; estimating a magnetism joint position based on world space positions of the one or more observed pixels assigned the magnetism body part; and shifting a joint of the machine-readable model toward the magnetism joint position.