VICARIOUS CALIBRATION OF THAICHOTE OVER THAILAND

摘要

This paper describes the radiometric calibration based on vicarious test site for Thaichote Satellite which was executed for the first time in Thailand on March 23rd, 2013 in order to verify the absolute gain coefficient of Thaichote multispectral sensor for converting digital numbers to at-sensor spectral radiance. First, the selection of test site in Thailand is based on two conditions which are the homogeneity and the site accessibility, the harvested sugarcane farm at Phukeaw in Chaiyaphum province, Northeast Thailand was a choice. The ground-based measurement data, that are ground reflectance of selected test site and atmospheric condition, was collected by a portable Spectroradiometer and a sunphotometer, along with Thaichote's image acquired simultaneously. The measurement data were used for estimating the actual at-sensor radiance and the absolute gain coefficients of each spectral band. Finally, the result from this calibration was compared with the gain ratio values (instrument and predicted) of the other ways of calibrations that were carried out in the past.