In the cross-calibration method, the response of the sensor under investigation is compared against a reference sensor that is believed to be well calibrated over time [19,20,24–26]. In order to achieve best results, a large homogeneous area is imaged simultaneously or nearly simultaneously by the two sensors using similar viewing angles, ideally nadir. Once spectral equivalency has been performed using the SBAF technique, for a stable atmosphere, the in-band radiances can be directly compared to determine any sensor calibration differences