A review of some radiometric calibration problems and methods

The in-flight radiometric calibration instrumentation and procedures of the Landsat Thematic Mapper and the high-resolution visible-range instruments of SPOT are illustrated with drawings and diagrams, characterized, and compared. Problems encountered in the laboratory calibration process, minimizing the temporal instability of the systems, identifying anomalies in the electronics in flight, and rechecking the calibration are examined, and it is pointed out that the stability of the calibration systems is less than that of the instruments themselves. The use of carefully measured ground-site data and atmospheric parameters in combination with radiative-transfer models for periodic calibration is recommended.