Radiometric Calibration and Characterization of Large-format Digital Photogrammetric Sensors in a Test Field

Test field calibration is an attractive approach to calibrating and characterizing the radiometry of airborne imaging instruments. In this study, a method for radiometric test field calibration for digital photogrammetric instruments is developed, and it is used to evaluate the radiometric performance of large-format photogrammetric sensors the ADS40, the DMC, and the UltraCam(D). In the study, linearity, dynamic range, sensitivity, and absolute calibration were evaluated. The results demonstrated the high radiometric quality of the sensors tested. All the sensors were linear in response. The DMC used the 12-bit dynamic range entirely, while the ADS40 and the UltraCam(D), indicated close to the 13-bit dynamic range. The sensors performed quite differently with respect to sensitivity. With the DMC and the UltraCam(D) a risk of overexposure appeared, while the color channels of the ADS40 showed low sensitivity. Because the sensors were linear in response, they could be absolutely calibrated using linear models.