Abstract

Six basic criteria used to estimate the Ground Resolution Distance of satellite imagers are considered: Ground Sample Distance (GSD), Rayleigh diffraction limit, ground spot size, generalized Rayleigh resolution criterion, Sparrow limit, and the full-width at half-maximum (FWHM) of the Point/Line Spread Function (PSF/LSF). Theoretical arguments and experimental results that support the use of the LSF FWHM as a spatial resolution metric are presented. The procedure to compute the LSF FWHM from the system modulation transfer function is reviewed and is used to compute the FWHM of the three ideal sensors as a function of their optical factor, contrasting these theoretical results with 22 in orbit measurements. Within this context, the limited range of validity of the GSD and the Rayleigh diffraction limit as spatial resolution estimators is assessed. The limitations of the LSF FWHM as a resolution estimator are also noted.