Joint image formation and anisotropy characterization in wide-angle SAR

Kush R. Varshney; Müjdat Çetin; John W. Fisher III; Alan S. Willsky

doi:10.1117/12.663974

17 May 2006 Joint image formation and anisotropy characterization in wide-angle SAR

Kush R. Varshney, Müjdat Çetin, John W. Fisher III, Alan S. Willsky

Proceedings Volume 6237, Algorithms for Synthetic Aperture Radar Imagery XIII; 62370D (2006) https://doi.org/10.1117/12.663974
Event: Defense and Security Symposium, 2006, Orlando (Kissimmee), Florida, United States

Abstract

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 ℓ_k-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.

Citation Download Citation

Kush R. Varshney, Müjdat Çetin, John W. Fisher III, and Alan S. Willsky "Joint image formation and anisotropy characterization in wide-angle SAR", Proc. SPIE 6237, Algorithms for Synthetic Aperture Radar Imagery XIII, 62370D (17 May 2006); https://doi.org/10.1117/12.663974

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