88 
S.l. 
89 
The Kansas simulator has been used to good effect in 
developing SAR image processing algorithms, investigating optimum 
incidence angle and radar frequency configurations for soil 
moisture determination and in preliminary analysis of target 
detection and discrimination within SAR scenes. On a more 
fundamental level, the simulated images can be used to generate 
interest within the user community (particularly if realistic 
images of areas covered by other sensors can be produced for 
comparison) and in training personnel in the interpretation of 
SAR imges, i.e. recognition of the effects of shadowing and 
layover and the basic differences between this form of image and 
a simple photograph. 
= 
Returning to the example of ERS-1, there is a need to make 
potential users aware of the potential of a C-band spaceborne 
imaging radar particularly in light of the proposed land 
applications satllite which forms a later mission in the ERS 
series. However, the problem within Europe is the lack of 
digitized terrain information comparable to that available in the 
United States (and on which the current Kansas University 
simulations are based). The need is, therefore, for a simulation 
program to develop the necessary digital databases, including 
classification of the digitized areas into terrain types and the 
derivation of realistic scattering models. The first area is the 
domain of cartographers and mapping establishments whilst the - 
latter is the realm of industrial and University research 
organisations. The area of land classification may be achieved 
by aerial (photographic) surveys or by use of data from 
overflight companies such as the Daedelus Airborne Thematic 
Mapper owned by Hunting Technical Surveys in the U.K. (which has 
produced very impressive images over areas of Europe and for 
which land classification algorithms are in existence.) The 
derivation of C-band scattering models demands a co-ordinated 
plan, making use of past and future measurement campaigns over 
Europe, with the empirical measurements being used to validate 
theoretically-developed models. 
CALIBRATION 
Introduction 
The purpose of this section is to provide, after a short 
review of techniques applied in the past to the calibration of 
synthetic aperture radars, some considerations for the 
organisation of calibration for future SAR missions.