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 each 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, wherein each of the articulated body portions of the model has at least one representative attract point; matching the representative attract point, for each of the articulated body portions of the model to the centroids for each of the articulated body portions of the object 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.