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Improved image alignment under the influence of elevation

Mahmut Arikan(1), Guang Liu(1) and Ramon Hanssen(1)

(1) Delft University of Technology, Kluyverweg 1, 2629HS, Delft, Netherlands

Abstract

Keyword: Image co-registration, interferometry, synthetic aperture radar (SAR)

Image coregistration is one of the crucial steps in interferometric SAR processing. To extract the correct signal of interest between two or more acqusitions, correct geometrical alignment at sub-pixel level should be estimated and corrected before further analysis of the signal. In many cases, a low-degree polynomial mapping of the slave to the master image geometry is sufficient for precise coregistration. In the presence of high elevational differences though, a polynomial approximation can be insufficiently precise, leading to local misregistration and a decreased success-rate in the detection of coherent targets. To avoid this problem, a priori available digital elevation models might provide a useful higher order prediction of the coregistration vectors, leading to better results in the coregistration, as suggested by several authors. Here we evaluate the influence of these and more advanced coregistration methods, and comment on their feasibility. To test our approach, we have selected the Kashmir region due to its rough topography and its potential for deformation monitoring. In the study we review methods of image co-registration in InSAR applications and present our implementation and improvement in radar interferometric processing software (Doris).

 

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