​InSAR Technology

InSAR Technology 

Interfer​ometric SAR (InSAR) calculates the change in surface height between two imaging times, by using radar to measure the distance from the satellite to the surface. InSAR very accurately calculates the change in distance from the satellite to the surface based on the measured phase change of each pixel between two image acquisition times.

An interferogram is created by plotting the phase change of each pixel using a colour scale. Each fringe (e.g. blue to blue) is like a contour line that represents half a wavelength: 2.8 cm for a C-Band SAR (such as RADARSAT-2 or Sentinel-1) or 1.4 cm for an X-Band SAR (such as TerraSAR-X).
A deformation map is created by adding up the phase changes from the interferogram to find the total subsidence or uplift – a process called unwrapping (similar to counting the contour lines).