3-D interferometric SAR algorithm for discontinuous distributed objects

Interferometric SAR offers the possibility to extract a quasi-threedimensional (sometimes called two-and-a-half-dimensional) image of the target scenario using only a one-dimensional scan. The image is generated by unwrapping the ambiguous (modulo 2/spl pi/) measured phase difference of two SAR images, yielding the absolute phase and therefore height information of a scatterer. However, phase unwrapping algorithms providing an elevation model of the scene can only be used for continuous objects. Discontinous or isolated objects would require a two-dimensional scan, which is not feasible for most of the current remote sensing applications. This paper presents an interferometric processing scheme using two different RF transmit frequencies to enlarge the unambiguous height range. The presented algorithm is capable of extracting height information for a continuous surface as well as for arbitrarily located isolated scatterers. Measurements performed in an anechoic chamber are used for verification.