Interferometric Synthetic Aperture Radar (InSAR for short), detects and measures displacement over time. The technology is based on the comparison of multiple radar (SAR) image pairs. InSAR specialists create interferograms when they compare the phase information of two SAR images; i.e. an interferogram represents the difference in phase between two images, calculated for each pixel. This difference in the wavelength’s phase denotes the amount of displacement that took place between the image acquisition dates. InSAR specialists have to do advanced processing techniques to remove contaminant signals such as atmosphere. And ultimately, the displacement results are presented visually over optical satellite imagery so that clients can easily interpret what locations are moving, by how much, when.
The use of radar to detect the velocity of a moving object is commonly used in many well known applications: by the military to detect the speed of an approaching aircraft, in baseball to measure the speed of the pitcher’s fastball, and by law enforcement to determine whether your car is speeding. InSAR is not significantly different. Only our radar waves travel more than 1000km roundtrip through space and the earth’s atmosphere.
Unlike optical satellite images, radar can penetrate through clouds and can work equally effective at night, leading to 98% image acquisition reliability. There are currently more than five radar satellite constellations orbiting Earth, with more coming in the next few years. Each satellite has its own unique set of specifications in terms of orbit frequency, resolution, operational flexibility, and image cost. 3vG is satellite independent; we choose the best data source for each project based on the area of interest and our client’s overall monitoring objectives.