Relative radiometric correction of QuickBird imagery using the side-slither technique on orbit

The QuickBird commercial imaging satellite is a pushbroom system with four multispectral bands covering the visible through near-infrared region of the spectrum and a panchromatic band. 6972 detectors in each MS band and 27888 detectors in the pan band must be calibrated. In an ideal sensor, a uniform radiance target will produce a uniform image. Unfortunately, raw imagery generated from a pushbroom sensor contains vertical streaks caused by variability in detector response, variability in electronic gain and offset, lens falloff, and particulate contamination on the focal plane. Relative radiometric correction is necessary to account for the detector-to-detector non-uniformity seen in raw imagery. A relative gain is calculated for each detector while looking at a uniform target such as an integrating sphere during ground calibrations, diffuser panel, or large desert target on-orbit. A special maneuver developed for QuickBird called the "Side-Slither" technique is discussed. This technique improves the statistics of a desert target and achieves superior non-uniformity correction in imagery. The "Side-Slither" technique is compared to standard techniques for calculation of relative gain and shows a reduction in the streaking seen in imagery.