With traditional Radar Interferometry (InSAR), the processing regimen is designed to extract surface elevation from two radar scenes taken from slightly different positions in space. These two scenes are combined to produce an Interferogram image which encodes the inter‑scene difference as a series of fringes with each fringe representing one wavelength of path length difference. The Unwrap Step then converts this series of fringes into pixel values which are proportional to the elevation.
Displacement Mapping, or Differential Interferometric Synthetic Aperture Radar (D-InSAR) is able to measure Earth surface displacements with a precision at the sub‑centimeter level. The software processing regimen is designed to quantitatively extract surface displacement that took place between the acquisition times of the two images. This technology has successfully been applied to tasks such as land subsidence and uplift (Strozzi et al., 2001), glacier motion (Lang, Rabus, and Dech, 2004), volcano swelling (Lu et al., 2002, Pritchard and Simons, 2004), landslides and earthquakes (Massonnet et al., 1994, Zebker et al., 1994), mining (Stow, 1996, Perski, 2000); hydrocarbon and water extraction (Fielding, Blom, and Goldstein, 1998) and various other Earth phenomena.