Multitemporal measurements gathered by EMISAR over the Foulum (Jutland) test site and AirSAR over the Wageningen test site provide an unrivalled opportunity to examine the factors affecting classification of northern European agricultural crops using both polarimetric and multitemporal information. Data analysis, guided by physical principles, has been used to investigate those polarimetric features most adapted to separating different classes of crops (with the emphasis on C band data). This has led to a hierarchical approach in which broad classes (e.g., spring vs. winter crops) are successively subdivided into more specific classes using the most appropriate polarimetric features. This direct scheme has been linked to statistical methods in order to permit adaptivity of the decision boundaries. Its performance is compared with data-driven methods as a function of the temporal evolution of the crop state.
