In the solar spectrum, sensors on Earth remote sensing satellites measure the radiance reflected by the atmosphere-Earth surface system illuminated by the sun. This signal depends on the surface reflectance, but it is also perturbed by two atmospheric processes, the gaseous absorption and the scattering by molecules and aerosols.
In the case of the Optical calibration, the basic idea is to be able to retrieve reflectance of the observed physical objects. The process can be split in 3 main steps:
The calibration and validation of the measurement systems are important to maintain the reliability and reproducibility of the SAR measurements, but the establishment of correspondence between quantities measured by SAR and physical measure requires scientific background. The SAR calibration module allows to estimate quantitative accuracy. For now only calibration of TerraSARX data is available.