ABSTRACT

Remote sensing consists of data acquisition by means of imaging sensors and has many important applications, for example, imaging of Earth’s surface and ocean ¤oors, assessment of crop conditions, deep-space exploration, and so on. Sensor systems, which may be airborne or satellite borne, are classi†ed into two categories [1]. The †rst one is passive sensors, such as aerial photography, infrared imaging, passive microwave radiometers, and so on, that make use of natural radiation emitted or re¤ected by the surface of the object being observed. The second category is that of active sensors, which have a transmitter and operate in the microwave range of the electromagnetic spectrum. These active sensors are represented by imaging and nonimaging radars, altimeters, scatterometers, and so on.