1. A method of modeling a human subject, the method comprising: receiving, from a single depth camera viewing a scene from a single perspective, a depth map of the scene including the human subject, the depth map including a depth for each of a plurality of depth-map pixels; for each of a plurality of depth-map pixels imaging the human subject, associating with that depth-map pixel a body-part likelihood that that depth-map pixel images a body part of the human subject; modeling the human subject with a plurality of plausible virtual skeletons each including a plurality of virtual joints, each virtual joint defined with a three-dimensional position derived from one or more depth-map pixels associated with a body-part likelihood corresponding to that virtual joint; and deriving a single virtual skeleton from the plurality of plausible virtual skeletons.