1. A method of tracking a human subject, the method comprising: obtaining an observed depth image including the human subject from a depth camera; generating a machine-readable model representing the human subject from the observed depth image; deriving a synthesized depth image from the machine-readable model representing the human subject, the synthesized depth image including a two-dimensional matrix of synthesized pixels, each synthesized pixel in the two-dimensional matrix of synthesized pixels including a depth value and having a same pixel address as a corresponding pixel of the observed depth image; determining, for each synthesized pixel, a depth difference between a depth of that synthesized pixel and a depth of a corresponding pixel from a subsequent observed depth image; and adjusting the machine-readable model representing the human subject into an adjusted pose based on the depth difference and different pixel cases for different ones of a plurality of synthesized pixels.