One embodiment of the present invention provides a system that assesses the quality of a process model. During operation, the system receives a mask layout and additionally receives a process model that models the effects of one or more semiconductor manufacturing processes on the mask layout. Next, the system computes a gradient of the process model with respect to a process model parameter. The system then computes a quality indicator at an evaluation point in the mask layout using the gradient of the process model and the mask layout. Next, the system assesses the quality of the process model using the quality indicator. In one embodiment, the system assesses the quality of the process model by comparing the quality indicator with a threshold.