It is possible to derive accurate topographic information from multiple SAR (synthetic aperture radar) images of a single region. In a broad sense, SAR interferometry is comparable to the use of stereo photography to determine topography of a region by observation from two different perspectives. However, SAR interferometry is applied not in the optical domain of photogrammetry, but in the realm of radar geometry, to exploit radar's ranging capability. Because SARs can accurately measure differences in slandt-range distances to the same feature from separate observation points, the technique can provide very accurate topographic information.
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