Physics concepts of optical and radar reflectance signatures A summary review

Five generically different signature types are identified and found to be important in remote sensing: spectral, spatial, angular, temporal and polarization signatures. Emphasis is placed on the description of angular signatures and atmospheric effects in the optical regime. Major differences between optical and radar remote sensing systems are noted and their consequences evaluated. Relative advantages and disadvantages of the two concepts are developed and compared. We conclude that optical and radar remote sensing are highly complementary; their respective signatures are often governed by different interaction processes so that the radar and optically sensed data complement each other instead of being redundant.