Would you explain SAR satellite imagery. How do interferometric techniques help analyse SAR data?
Dr Bamler: SAR is an active microwave imaging method. A radar onboard a satellite illuminates the Earth surface in a side-looking fashion. The transmitted waves are reflected back from the objects on ground and are recorded by the receiver in the satellite. In this way – and after further processing of the recorded signals – we generate an image of the radar reflectivity of the Earth surface. Since not only the power of the wave is recorded (this gives the brightness of a point in the images), but also the relative delay when it is received, we can use interferometeric techniques known as Interferometric SAR, or InSAR. To do that, we need at least two SAR images. If the two images are taken from different positions, say, a few hundred metres apart, the same area on ground is seen from two slightly different angles and we have a kind of stereo camera. The interferometric principle, i.e. the comparison of mutual wave shift, gives us the stereo parallaxes to within a fraction of a wavelen
