605 research outputs found
Sparse Signal Models for Data Augmentation in Deep Learning ATR
Automatic Target Recognition (ATR) algorithms classify a given Synthetic
Aperture Radar (SAR) image into one of the known target classes using a set of
training images available for each class. Recently, learning methods have shown
to achieve state-of-the-art classification accuracy if abundant training data
is available, sampled uniformly over the classes, and their poses. In this
paper, we consider the task of ATR with a limited set of training images. We
propose a data augmentation approach to incorporate domain knowledge and
improve the generalization power of a data-intensive learning algorithm, such
as a Convolutional neural network (CNN). The proposed data augmentation method
employs a limited persistence sparse modeling approach, capitalizing on
commonly observed characteristics of wide-angle synthetic aperture radar (SAR)
imagery. Specifically, we exploit the sparsity of the scattering centers in the
spatial domain and the smoothly-varying structure of the scattering
coefficients in the azimuthal domain to solve the ill-posed problem of
over-parametrized model fitting. Using this estimated model, we synthesize new
images at poses and sub-pixel translations not available in the given data to
augment CNN's training data. The experimental results show that for the
training data starved region, the proposed method provides a significant gain
in the resulting ATR algorithm's generalization performance.Comment: 12 pages, 5 figures, to be submitted to IEEE Transactions on
Geoscience and Remote Sensin
Classification of Radar Targets Using Invariant Features
Automatic target recognition ATR using radar commonly relies on modeling a target as a collection of point scattering centers, Features extracted from these scattering centers for input to a target classifier may be constructed that are invariant to translation and rotation, i.e., they are independent of the position and aspect angle of the target in the radar scene. Here an iterative approach for building effective scattering center models is developed, and the shape space of these models is investigated. Experimental results are obtained for three-dimensional scattering centers compressed to nineteen-dimensional feature sets, each consisting of the singular values of the matrix of scattering center locations augmented with the singular values of its second and third order monomial expansions. These feature sets are invariant to translation and rotation and permit the comparison of targets modeled by different numbers of scattering centers. A metric distance metric is used that effectively identifies targets under real world conditions that include noise and obscuration
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Fusing Deep Learning and Sparse Coding for SAR ATR
We propose a multimodal and multidiscipline data fusion strategy appropriate for automatic target recognition (ATR) on synthetic aperture radar imagery. Our architecture fuses a proposed clustered version of the AlexNet convolutional neural network with sparse coding theory that is extended to facilitate an adaptive elastic net optimization concept. Evaluation on the MSTAR dataset yields the highest ATR performance reported yet, which is 99.33% and 99.86% for the three- and ten-class problems, respectively
Target recognition for synthetic aperture radar imagery based on convolutional neural network feature fusion
Driven by the great success of deep convolutional neural networks (CNNs) that are currently used by quite a few computer vision applications, we extend the usability of visual-based CNNs into the synthetic aperture radar (SAR) data domain without employing transfer learning. Our SAR automatic target recognition (ATR) architecture efficiently extends the pretrained Visual Geometry Group CNN from the visual domain into the X-band SAR data domain by clustering its neuron layers, bridging the visual—SAR modality gap by fusing the features extracted from the hidden layers, and by employing a local feature matching scheme. Trials on the moving and stationary target acquisition dataset under various setups and nuisances demonstrate a highly appealing ATR performance gaining 100% and 99.79% in the 3-class and 10-class ATR problem, respectively. We also confirm the validity, robustness, and conceptual coherence of the proposed method by extending it to several state-of-the-art CNNs and commonly used local feature similarity/match metrics
Scattering Center Extraction and Recognition Based on ESPRIT Algorithm
Inverse Synthetic Aperture Radar (ISAR) generates high quality radar images even in low visibility. And it provides important physical features for space target recognition and location. This thesis focuses on ISAR rapid imaging, scattering center information extraction, and target classification.
Based on the principle of Fourier imaging, the backscattering field of radar target is obtained by physical optics (PO) algorithm, and the relation between scattering field and objective function is deduced. According to the resolution formula, the incident parameters of electromagnetic wave are set reasonably. The interpolation method is used to realize three-dimensional (3D) simulation of aircraft target, and the results are compared with direct imaging results.
CLEAN algorithm extracts scattering center information effectively. But due to the limitation of resolution parameters, traditional imaging can’t meet the actual demand. Therefore, the super-resolution Estimation of Signal Parameters via Rotational Invariance Techniques (ESPRIT) algorithm is used to obtain spatial target location information. The signal subspace and noise subspace are orthogonal to each other. By combining spatial smoothing method with ESPRIT algorithm, the physical characteristics of geometric target scattering center are obtained accurately. In particular, the proposed method is validated on complex 3D aircraft targets and it proves that this method is applied to most scattering mechanisms.
The distribution of scattering centers reflects the geometric information of the target. Therefore, the electromagnetic image to be recognized and ESPRIT image are matched by the domain matching method. And the classification results under different radii are obtained. In addition, because the neural network can extract rich image features, the improved ALEX network is used to classify and recognize target data processed by ESPRIT. It proves that ESPRIT algorithm can be used to expand the existing datasets and prepare for future identification of targets in real environments. Final a visual classification system is constructed to visually display the results
SAR ATR Method with Limited Training Data via an Embedded Feature Augmenter and Dynamic Hierarchical-Feature Refiner
Without sufficient data, the quantity of information available for supervised
training is constrained, as obtaining sufficient synthetic aperture radar (SAR)
training data in practice is frequently challenging. Therefore, current SAR
automatic target recognition (ATR) algorithms perform poorly with limited
training data availability, resulting in a critical need to increase SAR ATR
performance. In this study, a new method to improve SAR ATR when training data
are limited is proposed. First, an embedded feature augmenter is designed to
enhance the extracted virtual features located far away from the class center.
Based on the relative distribution of the features, the algorithm pulls the
corresponding virtual features with different strengths toward the
corresponding class center. The designed augmenter increases the amount of
information available for supervised training and improves the separability of
the extracted features. Second, a dynamic hierarchical-feature refiner is
proposed to capture the discriminative local features of the samples. Through
dynamically generated kernels, the proposed refiner integrates the
discriminative local features of different dimensions into the global features,
further enhancing the inner-class compactness and inter-class separability of
the extracted features. The proposed method not only increases the amount of
information available for supervised training but also extracts the
discriminative features from the samples, resulting in superior ATR performance
in problems with limited SAR training data. Experimental results on the moving
and stationary target acquisition and recognition (MSTAR), OpenSARShip, and
FUSAR-Ship benchmark datasets demonstrate the robustness and outstanding ATR
performance of the proposed method in response to limited SAR training data
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