A target tracking method includes representing a human target with a machine-readable model configured for adjustment into a plurality of different poses and receiving an observed depth image of the human target from a source. One or more push force vectors are applied to one or more force-receiving locations of the model to push the model in an XY plane towards a silhouette of the human target in the observed depth image when portions of the model are shifted away from the silhouette of the human target in the observed depth image. One or more pull force vectors are applied to one or more force-receiving locations of the model to pull the model in an XY plane towards the silhouette of the human target in the observed depth image when portions of the observed depth image are shifted away from the silhouette of the model.