CTV-Net: Complex-Valued TV-Driven Network With Nested Topology for 3-D SAR Imaging

The regularization-based approaches offer promise in improving synthetic aperture radar (SAR) imaging quality while reducing system complexity. However, the widely applied <inline-formula> <tex-math notation="LaTeX">\ell _{1} </tex-math></inline-formula> regularizat...

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Bibliographic Details
Published in:IEEE transaction on neural networks and learning systems Vol. 35; no. 4; pp. 5588 - 5602
Main Authors: Wang, Mou, Wei, Shunjun, Zhou, Zichen, Shi, Jun, Zhang, Xiaoling, Guo, Yongxin
Format: Journal Article
Language:English
Published: United States IEEE 01.04.2024
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
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ISSN:2162-237X, 2162-2388, 2162-2388
Online Access:Get full text
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Summary:The regularization-based approaches offer promise in improving synthetic aperture radar (SAR) imaging quality while reducing system complexity. However, the widely applied <inline-formula> <tex-math notation="LaTeX">\ell _{1} </tex-math></inline-formula> regularization model is hindered by their hypothesis of inherent sparsity, causing unreal estimations of surface-like targets. Inspired by the edge-preserving property of total variation (TV), we propose a new complex-valued TV (CTV)-driven interpretable neural network with nested topology, i.e., CTV-Net, for 3-D SAR imaging. In our scheme, based on the 2-D holography imaging operator, the CTV-driven optimization model is constructed to pursue precise estimations in weakly sparse scenarios. Subsequently, a nested algorithmic framework, i.e., complex-valued TV-driven fast iterative shrinkage thresholding (CTV-FIST), is derived from the theory of proximal gradient descent (PGD) and FIST algorithm, theoretically supporting the design of CTV-Net. In CTV-Net, the trainable weights are layer-varied and functionally relevant to the hyperparameters of CTV-FIST, which aims to constrain the algorithmic parameters to update in a well-conditioned tendency. All weights are learned by end-to-end training based on a two-term cost function, which bounds the measurement fidelity and TV norm simultaneously. Under the guidance of the SAR signal model, a reasonably sized training set is generated, by randomly selecting reference images from the MNIST set and consequently synthesizing complex-valued label signals. Finally, the methodology is validated, numerically and visually, by extensive SAR simulations and real-measured experiments, and the results demonstrate the viability and efficiency of the proposed CTV-Net in the cases of recovering 3-D SAR images from incomplete echoes.
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ISSN:2162-237X
2162-2388
2162-2388
DOI:10.1109/TNNLS.2022.3208252