QuickBird relative radiometric performance and on-orbit long term trending

摘要

One of the top radiometric priorities of the high-spatial resolution, commercial remote sensing industry is to achieve a superior level of image quality in all imagery products. Errors in detector gain and offset correction during product generation create noticeable image artifacts such as banding and streaking that degrade the overall image quality. Banding and streaking can be minimized by relative radiometric calibration, however, this calibration is only a temporary solution as the gain and offset of each detector will drift over time. The work presented here examines the relative radiometric performance of the QuickBird panchromatic and multispectral bands and tracks the performance from January 2005 until the present. During radiometric operations, uniform scenes of desert, ocean, forest, and snow areas are identified in the DigitalGlobe ImageLibrary. Products for these uniform scenes are generated and detector statistics are calculated for each scene. The QuickBird focal plane contains detectors that are masked so that no light reaches them. The statistics for the masked detectors are analyzed to study image-to-image variability and determine changes in detector offsets over time. Next, the detector averages for all active detectors are radiometrically corrected, and banding and streaking metrics are applied. Banding and streaking are trended to monitor changes over time. Quality metrics are also established based on the banding and streaking results to determine when the detector's gains and offsets have drifted sufficiently to require recalibration. Relative radiometric performance of the uniform scenes is compared with and without recalibration.