Joint image formation and anisotropy characterization in wide-angle SAR

Çetin, Müjdat and Varshney, Kush R. and Fisher, III, John W. (2006) Joint image formation and anisotropy characterization in wide-angle SAR. In: SPIE Defense and Security Symposium, Algorithms for Synthetic Aperture Radar Imagery XIII, Florida

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We consider the problem of jointly forming images and characterizing anisotropy from wide-angle synthetic aperture radar (SAR) measurements. Conventional SAR image formation techniques assume isotropic scattering, which is not valid with wide-angle apertures. We present a method based on a sparse representation of aspect-dependent scattering with an overcomplete basis composed of basis vectors with varying levels of angular persistence. Solved as an inverse problem, the result is a complex-valued, aspect-dependent response for each spatial location in a scene. Our non-parametric approach does not suffer from reduced cross-range resolution inherent in subaperture methods and considers all point scatterers in a scene jointly. The choice of the overcomplete basis set incorporates prior knowledge of aspect-dependent scattering, but the method is flexible enough to admit solutions that may not match a family of parametric functions. We enforce sparsity through regularization based on the ℓk-norm, k < 1. This formulation leads to an optimization problem that is solved through a robust quasi-Newton method. We also develop a graph-structured interpretation of the overcomplete basis leading towards approximate algorithms using guided depth-first search with appropriate stopping conditions and search heuristics. We present experimental results on synthetic scenes and the backhoe public release dataset.
Item Type: Papers in Conference Proceedings
Uncontrolled Keywords: synthetic aperture radar, wide-angle imaging, anisotropy, sparse signal representation, image formation, inverse problems.
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: Faculty of Engineering and Natural Sciences
Depositing User: Müjdat Çetin
Date Deposited: 19 Dec 2006 02:00
Last Modified: 26 Apr 2022 08:33

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