ABSTRACT
The need for interferometric measurements stems initially from practical issues of trying to improve the spatial resolution of passive imagers and altimeters, and finding some means of correcting the topographic distortion in imaging radar. In the passive imaging case, interferometry therefore gives a higher resolution 2-D image— it does not give any more information than students would get from a larger antenna. The approach of along-track interferometry is that the antennas are separated in the along-track direction — i.e. the baseline is parallel to the flight path. These are polarimetric interferometry and multi-baseline interferometry, both of which rely on models that describes the polarimetric and/or interferometric response from a vegetation canopy of a certain size and geometric properties. The small phase differences observed in the time sequence for a single pixel are then unwrapped into a steady change over time, which can be converted to a component of the displacement, as discussed for differential interferometry.
