1. A method for using simulation results to select evaluation points for a model-based optical proximity correction (OPC) operation, comprising: selecting critical segments in the layout; performing a dense simulation on the critical segments, wherein the dense simulation determines deviations between a desired layout and a simulated layout at multiple evaluation points on each of the critical segments; for each critical segment, selecting an evaluation point from the multiple evaluation points on the critical segment based on results of the dense simulation; and performing a model-based OPC operation using the selected evaluation point for each critical segment.