ABSTRACT
Interferometric synthetic aperture radar (IFSAR) is a technique used to reconstruct the digital elevation model (DEM) of the observed scene. This chapter describes the IFSAR principles and the related processing: image registration, phase unwrapping, and geocoding, which lead to the DEM in universal cartographic reference systems. To understand IFSAR principles some preliminary considerations are in order. The two images can be either obtained by means of a single system with two (one active and one passive) imaging sensors, or with two repeat passes of a single (active) imaging sensor system. A discussion about the achievable height accuracy of the previously mentioned stereometric system is now in order. As already stated IFSAR systems are based on extracting the phase difference from two synthetic aperture radar (SAR) images relative to the same scene. Displacement of the reference system axis from the antenna phase center trajectory shifts and scales (in range frequency) the slave spectrum with respect to the master antenna one.
