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An Efficient Method for Improving Coherence of Multi Aperture Interferogram (MAI)

Hyung-Sup Jung(1), Chang-Wook Lee(1), Sang-Wan Kim(2), Van Trung Nguyen(1) and Joong-Sun Won(1)

(1) Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, Korea
(2) Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143–747, Korea

Abstract

While conventional interferometric SAR (InSAR) technique is an excellent tool for displacement observation, it is only sensitive to one-dimensional deformation along the satellite’s line-of-sight (LOS). Recently, a multi aperture interferogram (MAI) technique has been developed to overcome this drawback. This method successfully extracted along-track displacements from InSAR data, based on split-beam InSAR processing, to create forward- and backward- looking interferograms, and was superior to along-track displacements derived by pixel-offset algorithm. While this method is useful to measure along-track displacements, it has a disadvantage that three co-registration and resampling procedures are required because MAI and two modified interferograms need to be constructed. Three co-registration and resampling procedures reduce the coherence of MAI and are time-consuming tasks. We propose an alternative efficient method to produce MAI. The proposed method extracts along-track displacements using two multi aperture complex (MAC) images instead of the forward- and backward- interferograms. The MAC images can be constructed from forward- and backward- single look complex (SLC) images co-registrated by time shift property of Fourier transform without co-registration and resampling procedures, where the time shift is estimated from the difference of Doppler centroid between forward- and backward- SLC images. The proposed method reduces the number of co-registration and resampling to one step, and consequently minimizes loss of coherence. We tested the proposed method using ERS images of the Mw 7.1 1999 California when the Hector Mine Earthquake occurred. The result shows that the proposed method decreased the processing time and improved the coherence of MAI.

 

Workshop presentation

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry