WorldView-1 pre and post-launch radiometric calibration and early on-orbit characterization

The WorldView-1 high spatial resolution commercial imaging satellite was launched on September 18, 2007. WorldVew-1 contains a single panchromatic band with a spectral range of 400-900 nm capable of collecting half-meter pixels on the ground with a swath width of 17.6 km. The instrument is a pushbroom scanner with a focal plane of 36400 detectors, six time-delayed integration (TDI) exposure rates, and bi-directional scanning. All of the detectors must be calibrated for each of the twelve TDI/scan direction combinations. A pre-launch radiometric calibration was performed on the instrument using a full-aperture integrating sphere and NIST-traceable transfer radiometers. The test data are used to determine the absolute radiometric calibration of the instrument in units of radiance per count and also generate the relative pixel-to-pixel gain and offset values for the non-uniformity correction. The relative gain and offset values are updated on orbit using uniform desert targets. Image quality metrics for banding and streaking are applied to the uniform scenes comparing calibration factors derived pre- and post-launch showing reduced values when using the updated calibration factors. Relative radiometric performance assessment of imagery collected in the first nine months on orbit shows that WorldView-1 has excellent radiometric image quality with banding better than 0.55% and streaking better than 0.23%. Long term trends show that banding and streaking are not changing significantly with time.