1. A computer readable storage device having computer readable software embodied thereon for programming at least one processor to perform a method for modeling a pose of articulated body portions of an object, the method comprising: obtaining depth pixels of the articulated body portions of the object in one or more frames; processing the depth pixels of the one or more frames to identify centroids of the articulated body portions of the object; accessing a model, the model includes articulated body portions which correspond to the articulated body portions of the object, and which each have at least one representative attract point; matching the representative attract points to the centroids and performing a rigid transform of the model, based on a comparison between the representative attract points and the centroids; refining the match by performing a non-rigid transform of the model based on a comparison between the representative attract points and the centroids, resulting in changes to relative orientations and locations of the articulated body portions of the model; and further refining the match by rasterizing the model to provide depth pixels of the model, and by performing a non-rigid transform of the model based on a comparison between the depth pixels of the one or more frames and the depth pixels of the model.