A method and apparatus have been developed to model wrapped phase data directly. An average statistical cost measures the misfit between the observed phase value modeled phase value. A set of acceptable values for the parameters in a parametric expression characterizing the wrapped phase is found by searching for an average statistical cost below a threshold. In the context of interferometry, the parameter values can then be used to determine the impact of a geophysical event on a geographic area. In the context of a global navigation satellite system (GNSS), such as the Global Positioning System (GPS), the values can be used to determine the position of a GNSS receiver.