Search results for: A Khenchaf
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The problem of Gaussian beam propagation is of significant interest for many physical disciplines, including optics, geophysics, and acoustics. Individual Gaussian beams are asymptotic solutions of Helmholtz's equation. Since they are insensitive to ray transition region, several techniques based on Gaussian beam are used to evaluate high frequency EM wave equation, which overcome partially or fully...
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Caustics problem is inherent to classical high frequency approximation such Geometrical Optics (GO), Geometric Theory of Diffraction (GTD), Uniform Theory of Diffraction (UTD) and Equivalents Current Methods (MCE). All these developments propose numerical estimations of the EM field scattered from reflection, diffraction, and multiple scattering from an object. In this paper we apply the Gaussian...
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Gaussian beams are asymptotic solutions of the Helmholtz equation within the paraxial approximation. As the amplitude distribution of these solutions along the direction perpendicular to the ray is Gaussian, with its maximum on the ray, these solutions are called Gaussian beams. Since they are insensitive to ray transition region [1]– [2] , several techniques based on Gaussian beam are used to evaluate...
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In this paper, we present a new approach based on scattering inversion process using a Small Perturbation Model (SPM). Indeed, The SPM model has been used to estimate physical proprieties of water area such as the temperature and salinity properties. Then, these water parameters are used to estimate Total Dissolved Salt (TDS) on Terra SAR-X (TSX) images. The surface parameters have been extracted...
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2014 IEEE Geoscience and Remote Sensing Symposium > 2289 - 2292
In the context of improving the responsiveness of a maritime surveillance service, we propose a ship detection algorithm in optical satellite imagery. The major objective is the detection of vessels of any sizes in any resolution images. Signatures of ships and false alarm sources are analyzed and the state of the art studied. The wavelet transform is used for extracting at different scales details...
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In the area of monitoring and observation by sea, land or air by the use of information is an important task for the decision. We are interested in the present work on the information processing for the recognition of radar targets from ISAR images. To provide the information necessary for the recognition phase, we propose an approach radar image processing based on the combination algorithms Fisher...
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2013 14th International Radar Symposium (IRS) > 1 > 258 - 263
In this paper, a new radar imaging method is proposed to estimate target reflectors height. This method uses multipath propagation over sea surface. A radar data simulator has been implemented to predict the backscattered electrical field from a marine scene. The marine scene comprises a linear sea surface and a set of isotropic reflectors located above the sea surface. Multipath propagation is modelled...
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Information Sciences > 2012 > 196 > Complete > 73-96
This paper presents an approach to aircraft target recognition using Inverse Synthetic Aperture Radar (ISAR) images. The goal of this work is to develop a robust algorithm to add Automated Target Recognition (ATR) capabilities to extract efficient feature vectors and ensure a comprehensive recognition process.In the first part on this paper, we used a database of ISAR images reconstructed from anechoic...
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In this paper, we will present an experimental validation of the results given in [1] about the hydrodynamic phenomena (nonlinear) produced by the breaking coastal waves on the co-polar scattering coefficients in the bistatic configuration (especially in forward propagation case). Actually, we have carried out different X-band experimental measurements of aluminum wave profile in an anechoic (echoless)...
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From the perspective of developing a ship detection algorithm on optical imagery, a statistical model is developed to approximate histograms from high-resolution images of the sea surface. This model is developed using an empirical approach based on analysis of hundreds of images acquired on all the oceans of the planet. Several statistical distributions are selected in agreement with the state of...
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The image segmentation is one of the most used steps in image processing applications. Indeed, this process enables us to extract feature vectors which could be useful for experts decision and recognition task. This paper deals with the radar images segmentation for recognition targets. However, the radar images, generally include noise resulting from the acquisition step and from the several techniques...
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In this paper, we will study the influence of nonlinear waves (breaking waves) on the EM signature (X-band) of a sea surface in bistatic case (forward propagation). Indeed, we will start the temporal numerical analysis of the scattering coefficient σHH of breaking waves in low-grazing-angle. Then we will explain in details the different scattering mechanism of breaking waves. In this work, we will...
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In this paper, a new method is proposed to find a point scatterer's height in a 3-D marine scene with a monostatic low-grazing angle coastal radar thanks to multipath propagation. A simulator is developed to predict electromagnetic scattering of a 3-D marine scene. Our work is twofold. Firstly, a marine scene is simulated with a three-dimensional linear sea-surface model. The scattering model used...
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Radar Cross Section (RCS) from sea surface carries rich informations about sea states. Many works have been developed to compute RCS from this surface. The Classical Moment Method became an effective tool since it works for a very large class of surface shapes and scattering mechanisms. However, it requires a small mesh step (λ/10) which produces a high number of unknowns. Besides, for a highly curved...
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In this paper, we represent numerical results which, validate our former work on the hydrodynamic effect (nonlinear) produced by breaking waves [1] in EM bistatic scattering coefficients. We calculated the scattering coefficient σHH of breaking waves in bi-static configurations as a function of time. Then, in this paper we represent the first experimental measurements, which have been carried out...
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The aim of this work is to quantify the observability of marine weather conditions using the bistatic Normalized Radar Cross Section (NRCS) from the sea surface. The mathematical model of the sea surface profiles is obtained from the Elfouhaily's spectrum and the NRCS are calculated using the Method of Moments (MoM). All of NRCS are recorded in some data sets depending on the weather conditions. Using...
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In this paper, we present in a first step an overview on different models of electromagnetic scattering by random rough surfaces especially the composite two-Scale Model - CTSM (in order one and two). The numerical results computed for the bistatic radar cross-section from random rough surfaces especially from the sea surface using the Cox & Munk'slopes distribution and the sea surface spectrum...
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We describe in this paper, data processing algorithms applied on radar image in order to extract feature descriptors and then to perform recognition task. Several kinds of descriptors can be used to acquire information about target characteristics from radar images such as ISAR (Inverse Synthetic Aperture Radar) images. This paper presents two types of vector descriptors extracted via two minds of...
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In this contribution, High Frequency Surface Wave (HFSW) radars are considered for target detection. These systems, commonly used for oceanographic purposes, are of interest in maritime surveillance because of their long range detection capabilities. Unfortunately, the received signals are strongly polluted by different noises. To improve target detection a method based on Morphological Component...
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This paper presents aircraft target recognition (ATR) system using Inverse Synthetic Aperture Radar (ISAR) images. Knowing the pose of the target can improve the ATR performance (recognition rate and computational complexity). So, we propose in this paper a new pose estimator from ISAR images, based on the axis of symmetry and the similarity measure. The method proposed is compared with several approaches...
