ATMOSPHERIC AND TOPOGRAPHIC CORRECTION OF PHOTOGRAMMETRIC AIRBORNE DIGITAL SCANNER DATA (ATCOR-ADS)

Digital airborne photogrammetric cameras have evolved from imagers to well-calibrated radiometric measurement devices. As such, the radiative transfer based processing of the acquired data to surface reflectance products has become feasible. Such processing allows for automatic and consistent compensation of the effects of the atmosphere and the topography, which is known from remote sensing applications as the atmospheric correction task. The motivation is both, a qualitative improvement of the outputs of the automatic processing chains as well as the possibility to develop remote sensing data products from the imagery. This paper presents the operational implementation of a radiative-transfer based radiometric correction method of the Leica’s ADS-80 image products. The method is developed on the basis of the ATCOR-4 technology. The ATCOR-4 atmospheric correction software inverts the MODTRAN R -5 radiative transfer code for atmospheric compensation of trace gas and aerosol influences as well as for topographic correction of the illumination field. The focus of the processing is twofold: for image products, the correction of topographic dependency of atmospheric scattering, depending on flight altitude, terrain height, and viewing angle is envisaged. For remote sensing products, the output shall be optimized for automatic quantitative processing, including the correction of irradiance variations and cast shadow effects. The implementation of these two procedures have been successfully tested for both types of applications. Validation results in comparison to in-field measurements indicate a reliable accuracy of the such produced reflectance spectra.