What are the limitations of interferometry?
Interferograms are subject to some limitations. The most influencing ones are temporal and geometric decorrelation. The position and orientation of objects on the ground can change in the time span between the two acquisitions, resulting in a problem know as temporal decorrelation, which limits the use of repeat-pass interferometry. Also geometric decorrelation can limit it. It consists of variations in reflectivity of the targets as a function of the incidence angle. Interferograms are also affected by two kinds of ambiguity. First, phase differences are given in fractions of cycles (all pixels have phase between 0 and 1), not as integer numbers of cycles. Second, interferograms provide relative phase changes, not absolute changes; that means we must already know a point with null deformation and refer all measurements to it. High deformation gradients cannot be measured. The limit is one interferometric fringe per pixel. There are also dimensional limitations: interferometry must be
