High-precision, fast DEM reconstruction method for spaceborne InSAR

The primary objective of the spaceborne interferometric synthetic aperture radar (InSAR) system is to develop a consistent global digital elevation model (DEM). The improvement of the processing speed in global interferometry missions while maintaining the accuracy is becoming an important issue. DEM reconstruction is the most time-consuming step in the data processing required for spaceborne InSAR. Based on a DEM reconstruction principle analysis, we exploited two basic characteristics of the mapping relation between the interferometric phase and 3-D position of target point. First, the relation between the 3-D position of the target point and the interferometric phase can be approximated using polynomials. Second, the corresponding polynomials change slowly in the local SAR images. Also, we verified the foundations of the two mentioned characteristics theoretically. Then, we proposed a fast method of DEM reconstruction based on this analysis. Detailed descriptions of the step and key parameters of the fast algorithm are provided. Finally, the repeat-pass interferometric data obtained using TerraSAR-X was used to test the presented method. The experimental results showed that a significant reduction in computation time is achieved with only a small loss in accuracy. The effectiveness and correctness of the proposed method were also validated.