1. A method for calibrating a model of a photolithography process, comprising: providing a computational model of a photolithography process, the computational model having an adjustable parameter; printing a first pattern with the photolithography process as a printed pattern; measuring an aspect of the printed pattern; using the computational model to calculate an image intensity at a location determined according to the measured aspect; minimizing a first cost function that comprises a first difference between the calculated image intensity and an intensity threshold; calculating a second cost function comprising a second difference between a measured critical dimension of the printed pattern and a critical dimension simulated by the computational model; minimizing the first cost function with respect to a model parameter; determining if the computational model predicts that a portion of a first pattern will not print; removing from a definition of the second cost function, the critical dimension of the portion of the first pattern that will not print; and minimizing the second cost function with respect to the model parameter.