Insar terrain height estimation using low-quality sparse DEMs

SAR nterferomctry (InSAR) is a technique for esimating topography using the phase difference beween coincident SAR images. Many regions of the Earth have existing topographic data that can be used to assist interferometric SAR processing. In the following, we show how coarse low-quality DEMs can be used ill the InSAR processing chain. In particular, coarse low-quality DEMs facilitate phase inwrapping by removing as much of the low resolution topographic phase as possible. The problem of unwrapping the residual phase is easier thall unwrapping the flat earth corrected interferogram phase because the local phase bandwidth is reduced in addition to the demodulation of the flat earth correction. Lower local ringe requency reduces the probability of residues and hence the probability of phase unvrapping difficulties. In addition, the coarse DEM can also be used to calibrate the interferogram phase by providing a height template for a fitting process.