SAR interferometry

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Synthetic aperture radar (SAR) interferometry is a powerful remote sensing technique for measuring the distance to the Earth's surface. It requires that the surface is imaged by the radar at least twice from almost the same position in space. The property measured is the phase of the reflected radar signal. The differences in phase between the two images produce interferometric fringes that will represent both the topography of the surface and any changes in position of the surface during the period between the acquisition of the two images (Murray and others, 2000).