Multi-Temporal SAR Interferometry

InSAR is a technique that uses interferograms, generated by complex conjugate multiplication of two SAR images, and extracts a deformation signal with millimetre accuracy, compensating other phase contributors, i.e., atmosphere, orbital errors, topography etc. Overcoming the decorrelation problem associated with conventional InSAR, Multi-Temporal SAR Interferometry (MT-InSAR), an advanced InSAR technique, utilizes multiple interferograms to generate a one-dimensional line-of-sight (1D-LOS) displacement map along with displacement time-series maps. The development and implementation of a few popular MT-InSAR processing methods, e.g., persistent scatterers SAR interferometry (PS-InSAR) and small baseline subset (SBAS), which worked on the concept of extracting measurement pixels from stacks of interferograms, has added new dimensions to visualize deformation patterns over a region of interest and thus immensely complements the more precise ground-based geodetic techniques. The gradually improved satellite revisit time period and continuous progress in the development of MT-InSAR algorithms have further strengthened the idea of using displacement time-series for safe forecasting of natural hazard events such as landslides, earthquakes, and subsidence. This chapter provides readers with an ample discussion of SAR basics with associated geometric distortions, conventional InSAR, and the problem of decorrelation, followed by the general architecture of MT-InSAR algorithms along with their advantages and limitations.