1,901 research outputs found
Sparse ground-penetrating radar imaging method for off-the-grid target problem
Cataloged from PDF version of article.Spatial sparsity of the target space in subsurface or through-the-wall imaging applications has been successfully used within the compressive-sensing framework to decrease the data acquisition load in practical systems, while also generating high-resolution images. The developed techniques in this area mainly discretize the continuous target space into grid points and generate a dictionary of model data that is used in image-reconstructing optimization problems. However, for targets that do not coincide with the computation grid, imaging performance degrades considerably. This phenomenon is known as the off-grid problem. This paper presents a novel sparse ground-penetrating radar imaging method that is robust for off-grid targets. The proposed technique is an iterative orthogonal matching pursuit-based method that uses gradient-based steepest ascent-type iterations to locate the off-grid target. Simulations show that robust results with much smaller reconstruction errors are obtained for multiple off-grid targets compared to standard sparse reconstruction techniques. (c) 2013 SPIE and IS&
A robust compressive sensing based technique for reconstruction of sparse radar scenes
Cataloged from PDF version of article.Pulse-Doppler radar has been successfully applied to surveillance and tracking of both moving and
stationary targets. For efficient processing of radar returns, delay–Doppler plane is discretized and FFT
techniques are employed to compute matched filter output on this discrete grid. However, for targets
whose delay–Doppler values do not coincide with the computation grid, the detection performance
degrades considerably. Especially for detecting strong and closely spaced targets this causes miss
detections and false alarms. This phenomena is known as the off-grid problem. Although compressive
sensing based techniques provide sparse and high resolution results at sub-Nyquist sampling rates,
straightforward application of these techniques is significantly more sensitive to the off-grid problem.
Here a novel parameter perturbation based sparse reconstruction technique is proposed for robust delay–
Doppler radar processing even under the off-grid case. Although the perturbation idea is general and can
be implemented in association with other greedy techniques, presently it is used within an orthogonal
matching pursuit (OMP) framework. In the proposed technique, the selected dictionary parameters are
perturbed towards directions to decrease the orthogonal residual norm. The obtained results show that
accurate and sparse reconstructions can be obtained for off-grid multi target cases. A new performance
metric based on Kullback–Leibler Divergence (KLD) is proposed to better characterize the error between
actual and reconstructed parameter spaces. Increased performance with lower reconstruction errors are
obtained for all the tested performance criteria for the proposed technique compared to conventional
OMP and 1 minimization techniques.
© 2013 Elsevier Inc. All rights reserve
Performance Analysis of Tomographic Methods against Experimental Contactless Multistatic Ground Penetrating Radar
Ground-penetrating radar (GPR) technology for underground exploration consists of the transmission of an electromagnetic signal in the ground for sensing the presence of buried objects. While monostatic or bistatic configurations are usually adopted, a limited number of multistatic GPR systems have been proposed in the scientific literature. In this article, we investigate the recovery performance of a specific and unconventional contactless multistatic GPR system, designed at the Georgia Institute of Technology for the subsurface imaging of antitank and antipersonnel plastic mines. In particular, for the first time, tomographic approaches are tested against this experimental multistatic GPR system, while most GPR processing in the scientific literature processes multimonostatic experimental data sets. First, by mimicking the system at hand, an accurate theoretical as well as numerical analysis is performed in order to estimate the data information content and the performance achievable. Two different tomographic linear approaches are adopted, i.e., the linear sampling method and the Born approximation (BA) method, this latter enhanced by means of the compressive sensing (CS) theoretical framework. Then, the experimental data provided by the Georgia Institute of Technology are processed by means of a multifrequency CS- and BA-based method, thus generating very accurate 3D maps of the investigated underground scenario
Feature detection algorithms in computed images
The problem of sensing a medium by several sensors and retrieving
interesting features is a very general one. The basic framework of the
problem is generally the same for applications from MRI,
tomography, Radar SAR imaging to subsurface imaging, even though the
data acquisition processes, sensing geometries and sensed properties are
different. In this thesis we introduced a new perspective to the
problem of remote sensing and information retrieval by studying the
problem of subsurface imaging using GPR and seismic sensors.
We have shown that if the sensed medium is sparse in some domain then it can be imaged using many fewer measurements than required by the standard methods. This leads to much lower data acquisition times and better images representing the medium. We have used the ideas from Compressive Sensing, which show that a small number of random measurements about a signal is sufficient to completely characterize it, if the signal is sparse or compressible in some domain. Although we have applied our ideas to the subsurface imaging problem, our results are general and can be extended to other remote sensing applications.
A second objective in remote sensing is information retrieval
which involves searching for important features in the computed image of
the medium. In this thesis we focus on detecting buried structures like
pipes, and tunnels in computed GPR or seismic images. The problem of
finding these structures in high clutter and noise conditions, and
finding them faster than the standard shape detecting methods like the
Hough transform is analyzed.
One of the most important contributions of this thesis is, where the
sensing and the information retrieval stages are unified in a single
framework using compressive sensing. Instead of taking lots of standard
measurements to compute the image of the medium and search the
necessary information in the computed image, a much smaller number of
measurements as random projections are taken. The
data acquisition and information retrieval stages are unified by using a
data model dictionary that connects the information to the sensor data.Ph.D.Committee Chair: McClellan, James H.; Committee Member: Romberg, Justin K.; Committee Member: Scott, Waymond R. Jr.; Committee Member: Vela, Patricio A.; Committee Member: Vidakovic, Bran
Modern GPR Target Recognition Methods
Traditional GPR target recognition methods include pre-processing the data by
removal of noisy signatures, dewowing (high-pass filtering to remove
low-frequency noise), filtering, deconvolution, migration (correction of the
effect of survey geometry), and can rely on the simulation of GPR responses.
The techniques usually suffer from the loss of information, inability to adapt
from prior results, and inefficient performance in the presence of strong
clutter and noise. To address these challenges, several advanced processing
methods have been developed over the past decade to enhance GPR target
recognition. In this chapter, we provide an overview of these modern GPR
processing techniques. In particular, we focus on the following methods:
adaptive receive processing of range profiles depending on the target
environment; adoption of learning-based methods so that the radar utilizes the
results from prior measurements; application of methods that exploit the fact
that the target scene is sparse in some domain or dictionary; application of
advanced classification techniques; and convolutional coding which provides
succinct and representatives features of the targets. We describe each of these
techniques or their combinations through a representative application of
landmine detection.Comment: Book chapter, 56 pages, 17 figures, 12 tables. arXiv admin note:
substantial text overlap with arXiv:1806.0459
Sparse Ground Penetrating Radar Acquisition: Implication for Buried Landmine Localization and Reconstruction
The effectiveness of the ground penetrating radar (GPR) imaging process and its capability of correctly reconstructing buried objects is strictly bounded to a correct acquisition strategy, both in terms of data density and regularity. In some GPR applications, such as landmine detection, these requirements may not be fulfiled due to logistical limitations and environmental obstacles. In the light of autonomous platform, possibly driven by a positioning device, the knowledge of the maximum affordable grid irregularity is essential. This experimental work, employing a data set acquired at a landmine test site, provides a demonstration that the same information content could be maintained even with a sparser data grid, compared to the commonly adopted requirements, mitigating the pressing demand for a precise samples positioning
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