1. A method for estimating a first predetermined parameter of an object with respect to a reference, comprising: assigning one of a plurality of predetermined potential values for the first parameter to a corresponding plurality of models representative of the object, each model having a respective model probability; updating the assigned potential value for the first parameter and the corresponding model probability in response to a measured value of a second predetermined parameter of the object to form a corresponding plurality of updated models, having respective updated first parameter and model probability; selecting one of the updated models in response to a corresponding updated model probability; and choosing the updated value of the first parameter for the selected updated model as an estimate of the first predetermined parameter.