1. A computer-implemented method of generating a model for simulating imaging performance of an optical imaging system; said method comprising the steps of: defining said optical imaging system and a process to be utilized by said optical imaging system; defining a first model representing the imaging performance of said optical imaging system and said process, said first model generating values corresponding to a developed image dimension and a latent image slope, defining a second model for estimating a line width roughness of a feature to be imaged, said second model utilizing said latent image slope values generated by said first model to estimate said line width roughness, wherein at least the steps of defining the first and second models are implemented by a computer, calibrating said first model using first experimental imaging data obtained from said optical imaging system and said process; obtaining simulated latent image slope values from simulated imaging data generated by said calibrated first model; obtaining second experimental imaging data associated with said first experimental imaging data from said optical imaging system and said process, said second experimental imaging data including line width roughness data; and calibrating said second model by selecting values for parameters contained in said second model such that said second model generates line width roughness estimates from the simulated latent image slope values, which correspond to the line width roughness data of the second experimental data within a predefined error tolerance.