Requirement of Ground Tie Points for InSAR DEM Generation

Ground tie points have been used to improve the accuracy of a DEM derived from interferometric SAR (InSAR) data. The number of tie points required for ensuring certain accuracy of the InSAR-derived DEM was investigated in this study in two ways. One is the least-squares estimate of the corrections to a DEM using tie points, and the other is using an optimization procedure to estimate the uncertainties in estimations of InSAR parameters, mainly the baseline length, tilt angle, and reference phase using tie points, and resultant DEM error. It was found that, in terms of required tie points, both give comparable results. The latter method, though, can be applied in more realistic cases to design the tie point acquisition strategy for a mission.