SPECTRAL UNIFORMITY EVALUATION OF REFERENCE SURFACES FOR AIRBORNE AND ORBITAL SENSORS ABSOLUTE CALIBRATION

Abstract

The extraction of quantitative information from data collected by either airborne or orbital electro optical sensors is only possible through a well-performed absolute calibration. The most common method of in-flight absolute calibration uses a reference surface. One of the most critical steps to implement this method is the reference surface characterization, which must be spectrally uniformity, among other features. This study presents the methodology used to assess the spectral uniformity of two potential areas for in-flight sensor calibration. Two surfaces were studied: (a) an area in Brazil of bare soil (quartz sand) and (b) Tuz Gölü salt flat in Turkey considered by the CEOS (Committee on Earth Observation Satellites) an official area for orbital sensors calibration. Radiometric measurements were carried out at various sampling points in these two areas. In addition, the study aims to describe and determine some of the main uncertainties sources involved in this process. According to the statistical criteria adopted, both reference surfaces have not been considered spectrally uniform.

Keywords: spectral uniformity, electro-optical sensors, absolute calibration.