Contents
What is InSAR technology?
InSAR (Interferometric Synthetic Aperture Radar) is a technique for mapping ground deformation using radar images of the Earth’s surface that are collected from orbiting satellites. Unlike visible or infrared light, radar waves penetrate most weather clouds and are equally effective in darkness.
What is InSAR used to measure?
Differential interferometric synthetic aperture radar (InSAR) is used to measure displacements on Earth’s surface to a precision of a few centimeters or less. InSAR data are largely used to study deformation caused by earthquakes, volcanic eruptions, glacier movements, landslides, and subsidence.
What is interferometry in remote sensing?
Terrestrial or ground-based SAR interferometry (GBInSAR or TInSAR) is a remote sensing technique for the displacement monitoring of slopes, rock scarps, volcanoes, landslides, buildings, infrastructures etc.
What is difference between SAR and InSAR?
A SAR signal contains amplitude and phase information. Interferometric SAR (InSAR) exploits the phase difference between two complex radar SAR observations of the same area, taken from slightly different sensor positions, and extracts distance information about the Earth’s terrain.
What is the principle of interferometry?
The working principle of Interferometry technology consists on a splitting of the light into two beams that travel different optical paths and are then combined to produce interference. Interferometric objectives allow the microscope to operate as interferometer; fringes are observed in the sample when it is in focus.
How does InSAR measure topography?
InSAR uses the phase information in two SAR images to determine the phase difference between each pair of corresponding image points, thus producing an interferogram. Interestingly, the first applications of InSAR were in Earth-based studies of topography of the Moon and Venus (Zisk 1972, Rumsey et al 1974).
What is radar baseline?
The distance between the two antenna positions (the so-called baseline) is a multiplier for the phase difference. For example, during the Shuttle Radar Topography Mission (SRTM) in February 2000, a second receiving antenna was deployed on a 60 m long slidable lattice grate.
What is the purpose of interferometry?
Because of their wide application, interferometers come in a variety of shapes and sizes. They are used to measure everything from the smallest variations on the surface of a microscopic organism, to the structure of enormous expanses of gas and dust in the distant Universe, and now, to detect gravitational waves.
Where are interferometers used?
In analytical science, interferometers are used to measure lengths and the shape of optical components with nanometer precision; they are the highest precision length measuring instruments in existence.
Is InSAR active or passive?
Active remote sensing uses and applications The Shuttle Radar Topography Mission (SRTM) uses inSAR which measures Earth’s elevation with two antennas. In only a couple days, SRTM has collected one of the most accurate digital elevation models of Earth.
What is critical baseline?
The critical baseline is the aperture separation perpendicular to the look direction at which the interferometric correlation becomes zero. Interferometers with longer wavelengths and finer resolution are. less sensitive to baseline decorrelation.
What is temporal baseline?
The time period between two successive visits – the repeat cycle or ‘temporal baseline’ in InSAR terminology – depends on the satellite orbit and is usually in the order of several days to roughly a month.