As Tomasz mentioned, a good initialization is required for the use of this method. This confuses me because the last sentence of the abstract and the paper itself states that the intended application of this work is "locating deformable objects". Since AAMs need to rely on some other method for estimating the location of the objects, it seems like they would be better suited for tasks that use the converged model parameters to describe intraclass variation. The person or expression could be identified by matching in parameter space after the best fit is found.