Four methods for the in-flight radiometric calibration and cross calib
ration of multispectral imaging sensors are described. Three make use
of ground-based reflectance, irradiance, and radiance measurements in
conjunction with atmospheric measurements and one compares calibration
s between sensors. Error budgets for these methods are presented and t
heir validation is discussed by reference to SPOT and TM results and s
hown to meet the EOS requirements in the solar-reflective range.