One embodiment of the present invention relates to a process that models critical-dimension (CD) scanning-electron-microscopy (CD-SEM) extraction during photolithography process model calibration. During operation, the process receives measured CD values which were obtained using a CD-SEM extraction process, wherein the CD-SEM extraction process determines a measured CD value for a feature by measuring multiple CD values of the feature along multiple electron beam scans. The process then determines simulated CD values, wherein a simulated CD value is determined based at least on a set of CD extraction cut-lines evenly placed around the target feature. During subsequent photolithography process model calibration, the process fits a parameter that models an aspect of the photolithography process based at least on both the measured CD values and the simulated CD values.