MARS provides valuable information to the Commission on European agriculture and enables informed decisions to be made on agricultural policy. During this phase a number of areas for additional functionality, improved maintainability and to allow wider distribution became apparent and on contract completion in 1993 a new project was initiated to generate a design for the re-engineering of the software. Calibration Standard calibration procedures are applied for differences in satellite sensors, signal degradation in time, solar zenith angle and Earth-Sun distance. Atmospheric correction Atmospheric correction is based on the 5S radiative transfer model.
Atmospheric transmittance is estimated from water vapour, oxygen and ozone data.
Correction factors are applied according to the calculated optical path length for each pixel. Cloud detection Cloud contamination in the image is automatically flagged for each pixel using four separate methods based on comparisons of the pixel values in different bands and the local gradient of pixel values. A composite mask is created using the logical OR of the flags. Chip matching Both vector and raster matching is performed. A similar principle is used for image matching.