We discuss the methodology of resist model calibration under various aspects and assess the resulting predictive accuracy. The study is performed on an extensive OPC data set which includes several thousands of CD values obtained with immersion lithography for the 45 nm technology node. We address practical aspects such as speed of calibration vs. size of calibration data set and the role of pattern selection for calibration. In particular, we show that a small subset of the data set is sufficient to provide accurate calibration results. However, the overall predictive power can strongly be enhanced if a few critical patterns are additionally included into the calibration data set. Besides, we demonstrate a significant impact of the illumination source shape (measured vs. nominal top hat) on the resulting model quality. Most importantly, it will be shown that calibrated resist models based on a 3D (topographic) mask description perform better than resist models based on a 2D (Kirchhoff) mask approximation. Also, we show that a resist model calibrated with one-dimensional (lines & spaces) structures only can successfully predict the printing behavior of two-dimensional patterns (end-of-line structures).