InSAR image processing process 2
Here is a typical analysis procedure to detect the surface deformation by the 2-pass method using DEM (Digital Elevation Model). We use two images called a master image and a slave image.
* Phase unwrapping
The phase acquired by InSAR is only measured in values between 0 and 360 degrees. Therefore, we cannot get the magnitude of deformation from it without modification. The phase that originally takes on a wide range of value is folded (wrapped) in the range between 0 and 360 degrees. The work of unwrapping and turning the phase back to the magnitude of deformation is called phase unwrapping. This valuable technique is essential to the 3-pass and 4-pass method, and can be applied to the automatization and the accuracy improvement of the baseline estimation, and the quantitative analysis by applying it to the baseline estimation and conclusive results.
In the process mentioned above, if the atmosphere delay affects the whole of the image, the image often have a large margin of error. Therefore, it is essential to perform the atmospheric compensation and calculate the time average of the interferograms formed at distinct times.
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