Under which conditions can interferometry be applied?
Interferometry can be applied when certain conditions are satisfied. For repeat pass interferometry the distance between the two flight lines should be no more than a certain value (about 1 km for ERS). SAR satellites are designed to repeat their orbits cyclically and generally this condition is satisfied. Other conditions are a terrain slope not too steep, signal wavelength long enough and a pixel resolution not too coarse. The degree of steepness, the wavelength and resolution acceptable depend on the distance between the two acquisitions. A further condition that must be satisfied is that the ground must be observed from the same direction in both images. Last point is that in general it is not possible to apply interferometry to couples of images belonging to different satellites with different sensor characteristics (for example with different wavelength or polarization). Also, images of the same satellite but belonging to different acquisition modes (ascending or descending) cann
