Assessment of Radiometric Sensitivity of EOC data by Spectral Measurements on Ground

초록

KOMPSAT, the first Korea multi-purpose satellite, has been providing remotely sensed images since the launch in December 1999. The radiometric characteristic of EOC images is not clear due to the inherent limitations on the on-board radiometric calibration function of the sensor system. In general, radiometric characteristics of remotely sensed images can be presented by the sensitivity of radiant flux reflected from various features on the earth. The objective of this study is to analyze the radiometric characteristic of EOC image. The reflectances of various targets were measured on ground by a portable spectroradiometer GER2600. The EOC recorded radiance of the same target was estimated from the radiative transfer model, LOWTRAN, by using the ground measured reflectance, atmospheric and solar angle data at the time of image capture, and the satellite and sensor parameters. By correlating the digital number (DN) in the EOC image to the corresponding radiance values estimated from LOWTRAN, we could find the approximate coefficients for the gain and offset. Gain coefficients obtained from the study were close to 1 that about the same value with other known satellite sensors.