Radiometric characterization of IKONOS multispectral imagery

A radiometric characterization of Space Imagingʹs IKONOS 4-m multispectral imagery has been performed by a National Aeronautics and Space Administration (NASA) funded team from NASA Stennis Space Center, the University of Arizona Remote Sensing Group (U of A RSG), and South Dakota State University (SDSU). Both intrinsic radiometry and the effects of Space Imaging processing on radiometry were investigated. Relative radiometry was examined with uniform Antarctic and Saharan sites. Absolute radiometric calibration was performed using reflectance-based vicarious calibration methods on several uniform sites imaged by IKONOS coincident with ground-based surface and atmospheric measurements. Ground-based data and the IKONOS spectral response function served as input to radiative transfer codes to generate a top-of-atmosphere (TOA) radiance estimate. Calibration coefficients derived from each vicarious calibration were combined to generate an IKONOS radiometric gain coefficient for each multispectral band assuming a linear response over the full dynamic range of the instrument. These calibration coefficients were made available to Space Imaging, which subsequently adopted them by updating its initial set of calibration coefficients. IKONOS imagery procured through the NASA Scientific Data Purchase was processed with or without a Modulation Transfer Function Compensation (MTFC) kernel. The radiometric effects of this kernel on various scene types were also investigated.