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1
Henson, Benjamin. "Image registration for sonar applications." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/19536/.
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This work develops techniques to estimate the motion of an underwater platform by processing data from an on-board sonar, such as a Forward Looking Sonar (FLS). Based on image registration, a universal algorithm has been developed and validated with in field datasets. The proposed algorithm gives a high quality registration to a fine (sub-pixel) precision using an adaptive filter and is suitable for both optical and acoustic images. The efficiency and quality of the result can be improved if an initial estimate of the motion is made. Therefore, a coarse (pixel-wide) registration algorithm is proposed, this is based on the assumption of local sparsity in the pixel motion between two images. Using a coarse and then fine registration, large displacements can be accommodated with a result that is to a sub-pixel precision. The registration process produces a displacement map (DM) between two images. From a sequence of DMs, an estimation of the sensor's motion is made. This is performed by a proposed fast searching and matching technique applied to a library of modelled DMs. Further, this technique exploits regularised splines to estimate the attitude and trajectory of the platform. To validate the results, a mosaic has been produced from three sets of in field data. Using a more detailed model of the acoustic propagation has the potential to improve the results further. As a step towards this a baseband underwater channel model has been developed. A physics simulator is used to characterise the channel at waymark points in a changing environment. A baseband equivalent representation of the time varying channel is then interpolated from these points. Processing in the baseband reduces the sample rate and hence reduces the run time for the model. A comparison to a more established channel model has been made to validate the results.
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Daniell, Oliver James. "Sonar image interpretation for sub-sea operations." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/2983.
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Mine Counter-Measure (MCM) missions are conducted to neutralise underwater explosives. Automatic Target Recognition (ATR) assists operators by increasing the speed and accuracy of data review. ATR embedded on vehicles enables adaptive missions which increase the speed of data acquisition. This thesis addresses three challenges; the speed of data processing, robustness of ATR to environmental conditions and the large quantities of data required to train an algorithm. The main contribution of this thesis is a novel ATR algorithm. The algorithm uses features derived from the projection of 3D boxes to produce a set of 2D templates. The template responses are independent of grazing angle, range and target orientation. Integer skewed integral images, are derived to accelerate the calculation of the template responses. The algorithm is compared to the Haar cascade algorithm. For a single model of sonar and cylindrical targets the algorithm reduces the Probability of False Alarm (PFA) by 80% at a Probability of Detection (PD) of 85%. The algorithm is trained on target data from another model of sonar. The PD is only 6% lower even though no representative target data was used for training. The second major contribution is an adaptive ATR algorithm that uses local sea-floor characteristics to address the problem of ATR robustness with respect to the local environment. A dual-tree wavelet decomposition of the sea-floor and an Markov Random Field (MRF) based graph-cut algorithm is used to segment the terrain. A Neural Network (NN) is then trained to filter ATR results based on the local sea-floor context. It is shown, for the Haar Cascade algorithm, that the PFA can be reduced by 70% at a PD of 85%. Speed of data processing is addressed using novel pre-processing techniques. The standard three class MRF, for sonar image segmentation, is formulated using graph-cuts. Consequently, a 1.2 million pixel image is segmented in 1.2 seconds. Additionally, local estimation of class models is introduced to remove range dependent segmentation quality. Finally, an A* graph search is developed to remove the surface return, a line of saturated pixels often detected as false alarms by ATR. The A* search identifies the surface return in 199 of 220 images tested with a runtime of 2.1 seconds. The algorithm is robust to the presence of ripples and rocks.
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Calder, Brian. "Bayesian spatial models for SONAR image interpretation." Thesis, Heriot-Watt University, 1997. http://hdl.handle.net/10399/1249.
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This thesis is concerned with the utilisation of spatial information in processing of high-frequency sidescan SONAR imagery, and particularly in how such information can be used in developing techniques to assist in mapping functions. Survey applications aim to generate maps of the seabed, but are time consuming and expensive; automatic processing is required to improve efficiency. Current techniques have had some success, but utilise little of the available spatial information. Previously, inclusion of such knowledge was prohibitively expensive; recent improvements in numerical simulations techniques has reduced the costs involved. This thesis attempts to exploit these improvements into a method for including spatial information in SONAR processing and in general to image and signal analysis. Bayesian techniques for inclusion of prior knowledge and structuring complex problems are developed and applied to problems of texture segmentation, object detection and parameter extraction. It is shown through experiments on groundtruth and real datasets that the inclusion of spatial context can be very effective in improving poor techniques or, conversely in allowing simpler techniques to be used with the same objective outcome (with obvious computational advantages). The thesis also considers some of the implementation problems with the techniques used, and develops simple modifications to improve common algorithms.
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Hendriks, Lukas Anton. "Image processing techniques for sector scan sonar." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2487.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2009.<br>ENGLISH ABSTRACT: Sonars are used extensively for underwater sensing and recent advances
in forward-looking imaging sonar have made this type of sonar an appropriate
choice for use on Autonomous Underwater Vehicles. The images
received from these sonar do however, tend to be noisy and when used
in shallow water contain strong bottom reflections that obscure returns
from actual targets.
The focus of this work was the investigation and development of post-processing
techniques to enable the successful use of the sonar images for automated navigation.
The use of standard image processing techniques for noise reduction
and background estimation, were evaluated on sonar images with varying
amounts of noise, as well as on a set of images taken from an AUV in
a harbour.
The use of multiple background removal and noise reduction techniques
on a single image was also investigated. To this end a performance
measure was developed, based on the dynamic range found in
the image and the uniformity of returned targets. This provided a means
to quantitatively compare sets of post-processing techniques and identify
the “optimal” processing.
The resultant images showed great improvement in the visibility of
target areas and the proposed techniques can significantly improve the
chances of correct target extraction.<br>AFRIKAANSE OPSOMMING: Sonars word algemeen gebruik as onderwater sensors. Onlangse ontwikkelings
in vooruit-kykende sonars, maak hierdie tipe sonar ’n goeie
keuse vir die gebruik op ’n Outomatiese Onderwater Voertuig. Die beelde
wat ontvang word vanaf hierdie sonar neig om egter raserig te wees, en
wanneer dit in vlak water gebruik word toon dit sterk bodemrefleksies,
wat die weerkaatsings van regte teikens verduister.
Die fokus van die werk was die ondersoek en ontwikkeling van naverwerkings
tegnieke, wat die sonar beelde bruikbaar maak vir outomatiese navigasie.
Die gebruik van standaard beeldverwerkingstegnieke vir ruis-onderdrukking
en agtergrond beraming, is geëvalueer aan die hand van sonar
beelde met verskillende hoeveelhede ruis, asook aan die hand van ’n stel
beelde wat in ’n hawe geneem is.
Verdere ondersoek is ingestel na die gebruik van meer as een agtergrond
beramings en ruis onderdrukking tegniek op ’n enkele beeld. Hierdie
het gelei tot die ontwikkeling van ’n maatstaf vir werkverrigting
van toegepaste tegnieke. Hierdie maatstaf gee ’n kwantitatiewe waardering
van die verbetering op die oorspronklike beeld, en is gebaseer op die
verbetering in dinamiese bereik in die beeld en die uniformiteit van die
teiken se weerkaatsing. Hierdie maatstaf is gebruik vir die vergelyking
van verskeie tegnieke, en identifisering van die “optimale” verwerking.
Die verwerkte beelde het ’n groot verbetering getoon in die sigbaarheid
van teikens, en die voorgestelde tegnieke kan ’n betekenisvolle bedrae lewer tot die suksesvolle identifisering van obstruksies.
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Callow, Hayden J. "Signal Processing for Synthetic Aperture Sonar Image Enhancement." Thesis, University of Canterbury. Electrical and Electronic Engineering, 2003. http://hdl.handle.net/10092/4000.
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This thesis contains a description of SAS processing algorithms, offering improvements in Fourier-based reconstruction, motion-compensation, and autofocus. Fourier-based image reconstruction is reviewed and improvements shown as the result of improved system modelling. A number of new algorithms based on the wavenumber algorithm for correcting second order effects are proposed. In addition, a new framework for describing multiple-receiver reconstruction in terms of the bistatic geometry is presented and is a useful aid to understanding. Motion-compensation techniques for allowing Fourier-based reconstruction in widebeam geometries suffering large-motion errors are discussed. A motion-compensation algorithm exploiting multiple receiver geometries is suggested and shown to provide substantial improvement in image quality. New motion compensation techniques for yaw correction using the wavenumber algorithm are discussed. A common framework for describing phase estimation is presented and techniques from a number of fields are reviewed within this framework. In addition a new proof is provided outlining the relationship between eigenvector-based autofocus phase estimation kernels and the phase-closure techniques used astronomical imaging. Micronavigation techniques are reviewed and extensions to the shear average single-receiver micronavigation technique result in a 3 - 4 fold performance improvement when operating on high-contrast images. The stripmap phase gradient autofocus (SPGA) algorithm is developed and extends spotlight SAR PGA to the wide-beam, wide-band stripmap geometries common in SAS imaging. SPGA supersedes traditional PGA-based stripmap autofocus algorithms such as mPGA and PCA - the relationships between SPGA and these algorithms is discussed. SPGA's operation is verified on simulated and field-collected data where it provides significant image improvement. SPGA with phase-curvature based estimation is shown and found to perform poorly compared with phase-gradient techniques. The operation of SPGA on data collected from Sydney Harbour is shown with SPGA able to improve resolution to near the diffraction-limit. Additional analysis of practical stripmap autofocus operation in presence of undersampling and space-invariant blurring is presented with significant comment regarding the difficulties inherent in autofocusing field-collected data. Field-collected data from trials in Sydney Harbour is presented along with associated autofocus results from a number of algorithms.
6
Williams, Neil. "Recognising objects in sector-scan sonar image sequences." Thesis, Heriot-Watt University, 1998. http://hdl.handle.net/10399/1176.
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7
Beattie, Robert Scott. "Side scan sonar image formation, restoration and modelling." Thesis, Robert Gordon University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318551.
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8
Ng, Ferdinand. "Calibration and image formation in the ABACUS sonar system." Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/5138.
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9
McClelland, Scott C. "A rolling line source for a seismic sonar." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Jun%5FMcClelland.pdf.
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Carey-Smith, Christopher M. "Electronic stabilisation of sector scanning sonar displays." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/32623.
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MacLean, Douglas J. "Mobile source development for seismic-sonar based landmine detection." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FMacLean.pdf.
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Karpi, Stephen C. "The influence of shallow water variability on short range water-bourne propagation." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FKarpi.pdf.
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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, December 2002.<br>Thesis advisor(s): Kevin B. Smith, Peter H. Dahl. Includes bibliographical references (p. 53). Also available online.
13
Boland, Matthew R. "Examination of the use of exact versus approximate phase weights on the performance of a synthetic aperture sonar system." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Mar%5FBoland.pdf.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, March 2003.<br>Thesis advisor(s): Lawrence J. Ziomek, Ziaoping Yun. Includes bibliographical references (p. 63). Also available online.
14
Mulligan, David John. "An FPGA Coprocessor for Real-Time Bathymetric Synthetic Aperture Sonar." Thesis, University of Canterbury. Electrical and Computer Engineering, 2007. http://hdl.handle.net/10092/1232.
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The following is a thesis for a Master's degree in Electrical Engineering. It presents the design of an FPGA coprocessor for real-time bathymetric synthetic aperture sonar. Bathymetry is the process of finding the height of the seafloor; a problem that requires the computation of a large number of short-length correlations and runs slowly on a conventional microprocessor architecture. It is desirable to generate the seafloor bathymetry in real time for use as a visual aid during data gathering, thus the development of a customised coprocessor is required. The design presented utilises the system-on-chip (SoC) approach to FPGA programming, with a microprocessor, memory, communication cores and custom hardware all contained within a single chip. The merits of SoC design are examined and the details of this implementation are presented. The coprocessor communicates with a host computer over a USB link, receiving raw data as it is collected and sending processed data back to be displayed on-screen. The system was successful as a proof-of-concept, capable of processing an eighth of the area imaged by the sonar in real-time. The results for a simulated scene are presented and the performance of the current system examined with a view to improving its capabilities. While further work is required to implement a complete solution to the problem, the work carried out thus far has provided a solid base for future research.
15
Rumph, Steven E. "Development of four-element end-fire array as seismo-acoustic sonar source." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03sep%5FRumph.pdf.
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Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, September 2003.<br>Thesis advisor(s): Steven R. Baker, Thomas G. Muir. Includes bibliographical references (p. 89-90). Also available online.
16
Clarke, Stuart J. "The analysis and synthesis of texture in sidescan sonar data." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/791.
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Ingold, Barry W. Healey Anthony J. "Key feature identification from image profile segments using a high frequency sonar." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from the National Technical Information Service, 1992. http://handle.dtic.mil/100.2/ADA261926.
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Ingold, Barry W. "Key feature identification from image profile segments using a high frequency sonar." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/38505.
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Approved for public release; distribution is unlimited.<br>Many avenues have been explored to allow recognition of underwater objects by a sensing system on an Autonomous Underwater Vehicle (AUV). In particular, this research analyzes the precision with which a Tritech ST1000 high resolution imaging sonar system allows the extraction of linear features from its perceived environment. The linear extraction algorithm, as well as acceptance criteria for individual sonar returns are developed. Test results showing the actual sonar data and the sonar's perceived environment are presented. Additionally, position of the sonar relative to the perceived image is determined based on the identification of key points in the scene.
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Kiernan, Mary. "Implementation and design of the discrete Gabor filter for sonar texture classification." Thesis, Heriot-Watt University, 1995. http://hdl.handle.net/10399/766.
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Shibley, Jordan Almon. "Enhanced Sonar Array Target Localization Using Time-Frequency Interference Phenomena." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/1488.
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The ability of traditional active sonar processing methods to detect targets is often limited by clutter and reverberation from ocean environments. Similarly, multipath arrivals from radiating sources such as ships and submarines are received at sensors in passive sonar systems. Reverberation and multipath signals introduce constructive and destructive interference patterns in received spectrograms in both active and passive sonar applications that vary with target range and frequency. The characterization and use of interference phenomena can provide insights into environmental parameters and target movement in conjunction with standard processing methods including spectrograms and array beamforming.
This thesis focuses on utilizing the time-frequency interference structure of moving targets captured on sonar arrays to enhance the resolution and abilities of conventional sonar methods to detect and localize targets. Physics-based methods for interference-based beamforming and target depth separation are presented with application of these methods shown using broadband simulated array data.
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Gendron, Marlin. "Algorithms and Data Structures for Automated Change Detection and Classification of Sidescan Sonar Imagery." ScholarWorks@UNO, 2004. http://scholarworks.uno.edu/td/210.
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During Mine Warfare (MIW) operations, MIW analysts perform change detection by visually comparing historical sidescan sonar imagery (SSI) collected by a sidescan sonar with recently collected SSI in an attempt to identify objects (which might be explosive mines) placed at sea since the last time the area was surveyed. This dissertation presents a data structure and three algorithms, developed by the author, that are part of an automated change detection and classification (ACDC) system. MIW analysts at the Naval Oceanographic Office, to reduce the amount of time to perform change detection, are currently using ACDC. The dissertation introductory chapter gives background information on change detection, ACDC, and describes how SSI is produced from raw sonar data. Chapter 2 presents the author's Geospatial Bitmap (GB) data structure, which is capable of storing information geographically and is utilized by the three algorithms. This chapter shows that a GB data structure used in a polygon-smoothing algorithm ran between 1.3 – 48.4x faster than a sparse matrix data structure. Chapter 3 describes the GB clustering algorithm, which is the author's repeatable, order-independent method for clustering. Results from tests performed in this chapter show that the time to cluster a set of points is not affected by the distribution or the order of the points. In Chapter 4, the author presents his real-time computer-aided detection (CAD) algorithm that automatically detects mine-like objects on the seafloor in SSI. The author ran his GB-based CAD algorithm on real SSI data, and results of these tests indicate that his real-time CAD algorithm performs comparably to or better than other non-real-time CAD algorithms. The author presents his computer-aided search (CAS) algorithm in Chapter 5. CAS helps MIW analysts locate mine-like features that are geospatially close to previously detected features. A comparison between the CAS and a great circle distance algorithm shows that the CAS performs geospatial searching 1.75x faster on large data sets. Finally, the concluding chapter of this dissertation gives important details on how the completed ACDC system will function, and discusses the author's future research to develop additional algorithms and data structures for ACDC.
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Keeton, Jane A. "The use of image analysis techniques to characterise mid-ocean ridges from multibeam and sidescan sonar data." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/1620/.
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Elbergui, Ayda. "Amélioration des techniques de reconnaissance automatique de mines marines par analyse de l'écho à partir d'images sonar haute résolution." Thesis, Brest, 2013. http://www.theses.fr/2013BRES0042/document.
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La classification des cibles sous-marines est principalement basée sur l'analyse de l'ombre acoustique. La nouvelle génération des sonars d'imagerie fournit une description plus précise de la rétrodiffusion de l'onde acoustique par les cibles. Par conséquent, la combinaison de l'analyse de l'ombre et de l'écho est une voie prometteuse pour améliorer la classification automatique des cibles. Quelques systèmes performants de classification automatique des cibles s'appuient sur un modèle pour faire l'apprentissage au lieu d'utiliser uniquement des réponses expérimentales ou simulées de cibles pour entraîner le classificateur. Avec une approche basée modèle, un bon niveau de performance en classification peut être obtenu si la modélisation de la réponse acoustique de la cible est suffisamment précise. La mise en œuvre de la méthode de classification a nécessité de modéliser avec précision la réponse acoustique des cibles. Le résultat de cette modélisation est un simulateur d'images sonar (SIS). Comme les sonars d'imagerie fonctionnent à haute et très haute fréquence le modèle est basé sur le lancer de rayons acoustiques. Plusieurs phénomènes sont pris en compte pour augmenter le réalisme de la réponse acoustique (les effets des trajets multiples, l'interaction avec le fond marin, la diffraction, etc.). La première phase du classificateur utilise une approche basée sur un modèle. L'information utile dans la signature acoustique de la cible est nommée « A-scan ». Dans la pratique, l'A-scan de la cible détectée est comparé à un ensemble d'A-scans générés par SIS dans les mêmes conditions opérationnelles. Ces gabarits (A-scans) sont créés en modélisant des objets manufacturés de formes simples et complexes (mines ou non mines). Cette phase intègre un module de filtrage adapté pour permettre un résultat de classification plus souple capable de fournir un degré d'appartenance en fonction du maximum de corrélation obtenu. Avec cette approche, l'ensemble d'apprentissage peut être enrichi afin d'améliorer la classification lorsque les classes sont fortement corrélées. Si la différence entre les coefficients de corrélation de l'ensemble de classes les plus probables n'est pas suffisante, le résultat est considéré ambigu. Une deuxième phase est proposée afin de distinguer ces classes en ajoutant de nouveaux descripteurs et/ou en ajoutant davantage d'A-scans dans la base d'apprentissage et ce, dans de nouvelles configurations proches des configurations ambiguës. Ce processus de classification est principalement évalué sur des données simulées et sur un jeu limité de données réelles. L'utilisation de l'A-scan a permis d'atteindre des bonnes performances de classification en mono-vue et a amélioré le résultat de classification pour certaines ambiguïtés récurrentes avec des méthodes basées uniquement sur l'analyse d'ombre<br>Underwater target classification is mainly based on the analysis of the acoustic shadows. The new generation of imaging sonar provides a more accurate description of the acoustic wave scattered by the targets. Therefore, combining the analysis of shadows and echoes is a promising way to improve automated target classification. Some reliable schemes for automated target classification rely on model based learning instead of only using experimental samples of target acoustic response to train the classifier. With this approach, a good performance level in classification can be obtained if the modeling of the target acoustic response is accurate enough. The implementation of the classification method first consists in precisely modeling the acoustic response of the targets. The result of the modeling process is a simulator called SIS (Sonar Image Simulator). As imaging sonars operate at high or very high frequency the core of the model is based on acoustical ray-tracing. Several phenomena have been considered to increase the realism of the acoustic response (multi-path propagation, interaction with the surrounding seabed, edge diffraction, etc.). The first step of the classifier consists of a model-based approach. The classification method uses the highlight information of the acoustic signature of the target called « A-scan ». This method consists in comparing the A-scan of the detected target with a set of simulated A-scans generated by SIS in the same operational conditions. To train the classifier, a Template base (A-scans) is created by modeling manmade objects of simple and complex shapes (Mine Like Objects or not). It is based on matched filtering in order to allow more flexible result by introducing a degree of match related to the maximum of correlation coefficient. With this approach the training set can be extended increasingly to improve classification when classes are strongly correlated. If the difference between the correlation coefficients of the most likely classes is not sufficient the result is considered ambiguous. A second stage is proposed in order to discriminate these classes by adding new features and/or extending the initial training data set by including more A-scans in new configurations derived from the ambiguous ones. This classification process is mainly assessed on simulated side scan sonar data but also on a limited data set of real data. The use of A-scans have achieved good classification performances in a mono-view configuration and can improve the result of classification for some remaining confusions using methods only based on shadow analysis
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Quidu, Isabelle. "Classification multi-vues d'un objet immergé à partir d'images sonar et de son ombre portée sur le fond." Phd thesis, Université de Bretagne occidentale - Brest, 2001. http://tel.archives-ouvertes.fr/tel-00504902.
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La classification sur ombre de mines marines peut être effectuée à partir d'images sonar haute résolution. Cependant, la classification mono-vue admet des limites du fait de leur forme géométrique parfois complexe. Une manière de s'affranchir des ambiguïtés consiste à effectuer une classification multi-vues. Dans un premier temps, il convient d'assimiler les spécificités de l'imagerie sonar. D'un côté, les propriétés statistiques des pixels et le principe d'acquisition des images sont des connaissances avantageusement prises en compte lors de l'étape de segmentation. D'un autre côté, les distorsions géométriques qui affectent l'ombre portée du fait des performances du sonar et de la prise de vue doivent être considérées. En matière de reconnaissance de formes, les données sonar segmentées peuvent être diversement résumées suivant qu'on s'attache à définir des grandeurs indépendantes des positions relatives objet-sonar et/ou de la résolution du sonar ou bien, autorisant une reconstruction du contour et la conservation de l'orientation de la forme associée. Ces considérations du problème mono-vue ont préparé l'élaboration de processus plus complexes de classification multi-vues. D'une part, on manipule les attributs issus d'un traitement image par image. Deux cas se présentent : en exploitant l'évolution de la forme de l'ombre en fonction du trajet du sonar ou, au contraire, en s'affranchissant des transformations du plan. Dans le premier cas, on caractérise de manière globale l'ensemble des valeurs successives prises par des attributs sensibles aux diverses formes de l'ombre. Dans le second cas, sans connaissance précise des conditions d'acquisition, les attributs extraits sont fusionnés et présentés à l'opérateur sous forme de mesures pour l'aide à la décision. Par la logique floue d'autre part, les outils de reconnaissance de formes calculés sur des données binaires ont été étendus au cas de données en niveaux de gris d'une nouvelle image pour sa caractérisation.
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Mosca, Frédéric. "Synthèse d'émission spatio-temporelle pour l'imagerie acoustique." Phd thesis, Télécom ParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00574356.
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La recherche d'un compromis entre cadence et qualité de l'image est un enjeu majeur dans la définition de nouvelles méthodes d'imagerie cohérente. L'objectif de cette thèse est de proposer des modes d'imagerie innovants exploitant au mieux les performances des plateformes matérielles. Les applications étant l'échographie ultrasonore et l'acoustique sous-marine. Le manuscrit propose d'abord un cadre formel au problème du compromis cadence/contraste et démontre l'optimalité des méthodes de synthèse d'émission. L'équivalence, en termes de contraste et de résolution, entre la synthèse canonique et l'imagerie focalisée est ensuite établie. Le problème du rapport signal à bruit est adressé par l'utilisation de matrice d'émission maximisant l'énergie d'insonification (matrice de Hadamard). On introduit ensuite une méthode originale, dite d' " allègement de synthèse ", permettant une amélioration significative de la cadence. Pour cela, on recherche un optimum matriciel en terme de maximisation de l'énergie des faisceaux d'émission dans la zone d'insonification. Cet optimum est une matrice composée de séquences sphéroïdales aplaties. On introduit alors la " synthèse sphéroïdale " qui exploite les propriétés de cette matrice et permet de déplacer le compromis cadence/contraste en un compromis cadence/taille de l'image. La dernière partie de ce manuscrit est consacrée à la mesure et la correction des mouvements propres de la plateforme par des méthodes de micronavigation. Les résultats de ce travail de thèse font l'objet de validations expérimentales sur un échographe ultrasonore à 128 voies programmables et sur un sonar à antenne synthétique.
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Di, Martino Jean Claude. "Intégration de connaissances dans des systèmes distribués pour l'extraction de raies spectrales dans des images sonar." Nancy 1, 1995. http://www.theses.fr/1995NAN10008.
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Nous présentons dans cette thèse un système complet d'extraction d'indices dans des images bruitées. L’objectif est de fournir des primitives robustes et limitées en nombre aux niveaux supérieurs d'un traitement de reconnaissance de formes. Dans le cadre des systèmes sonar qui ont servi d'application à ce travail, l'information pertinente est définie sous la forme de courbes correspondant à l'évolution spectrale du signal dans le temps. Une part importante de notre travail consiste à définir les connaissances qui caractérisent les structures recherchées et à étudier leur modélisation dans les différents traitements mis en œuvre pour extraire ces primitives. Cette étude montre l'intérêt de l'apport de connaissances globales d'ordre perceptuel pour renforcer des connaissances locales parfois insuffisantes. Nous analysons chaque étape de traitement et proposons pour chacune d'elle une solution originale à partir de techniques d'intelligence artificielle (réseaux de neurones, traitements distribués, programmation dynamique) mais également à partir de techniques de traitement d'images (filtrage, détection de contours). Il ressort de cette étude que les traitements proposes de détection et d'association d'indices permettent de trouver de manière efficace les structures recherchées au détriment parfois d'une précision quant à leur localisation. Ceci nous a amène à compléter ce schéma de traitement en introduisant une étape supplémentaire originale de suivi guidée par les indices déjà extraits. Les résultats obtenus avec cette méthode montrent un gain significatif des performances en localisation des courbes extraites, pour un coût supplémentaire négligeable en temps d'exécution
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Sac, Hakan. "Opti-acoustic Stereo Imaging." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614782/index.pdf.
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In this thesis, opti-acoustic stereo imaging, which is the deployment of two-dimensional (2D) high frequency imaging sonar with the electro-optical camera in calibrated stereo configuration, is studied.
Optical cameras give detailed images in clear waters. However, in dark or turbid waters, information coming from electro-optical sensor is insufficient for accurate scene perception. Imaging sonars, also known as acoustic cameras, can provide enhanced target details under these scenarios. To illustrate these visibility conditions, a 2D high frequency imaging sonar simulator as well as an underwater optical image simulator is developed. A computationally efficient algorithm is also proposed for the post-processing of the returned sonar signals.
Where optical visibility allows, integration of the sonar and optical images effectively provides binocular stereo vision capability and enables the recovery of three-dimensional (3D) structural information. This requires solving the feature correspondence problem for these completely different sensing modalities. Geometrical interpretation of this problem is examined on the simulated optical and sonar images. Matching the features manually, 3D reconstruction performance of opti-acoustic system is also investigated. In addition, motion estimation from opti-acoustic image sequences is studied.
Finally, a method is proposed to improve the degraded optical images with the help of sonar images. First, a nonlinear mapping is found to match local the features in opti-acoustical images. Next, features in the sonar image is mapped to the optical image using the transformation. Performance of the mapping is evaluated for different scene geometries.
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Maussang, Frédéric. "Traitement d'images et fusion de données pour la détection d'objets enfouis en acoustique sous-marine." Phd thesis, Université Joseph Fourier (Grenoble), 2005. http://tel.archives-ouvertes.fr/tel-00011447.
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La détection et la classification d'objets enfouis est un problème particulièrement délicat : les techniques de sonar à antenne synthétiques utilisées pour imager le fond sous-marin fournissent des données possédant souvent un très faible rapport signal à bruit, d'où un nombre important de fausses alarmes. L'objectif de la thèse est de concevoir et développer des algorithmes permettant de réduire le nombre de fauses alarmes, tout en conservant une bonne détection, et éventuellement de classifier les objets détectés, grâce à des outils de traitement d'images et de fusion de données.Pour cela, on utilise les propriétés statistiques aux ordres 1, 2, 3 et 4 de ces images sonar qui vont nous permettre de développer des algorithmes de détection performants. Afin d'améliorer le résultat, les données ainsi extraites sont fusionnées dans un processus basé sur la théorie de l'évidence. Ceci permet de classifier chaque pixel de l'image en "objet" ou "non objet" selon qu'il est supposé appartenir à un objet recherché (mine sous-marine par exemple) ou pas. Le résultat pourra alors être utilisé par un expert afin de l'aider dans sa prise de décision.
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Zraqou, Jamal Sami. "Automated system design for the efficient processing of solar satellite images : developing novel techniques and software platform for the robust feature detection and the creation of 3D anaglyphs and super-resolution images for solar satellite images." Thesis, University of Bradford, 2011. http://hdl.handle.net/10454/5434.
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The Sun is of fundamental importance to life on earth and is studied by scientists from many disciplines. It exhibits phenomena on a wide range of observable scales, timescales and wavelengths and due to technological developments there is a continuing increase in the rate at which solar data is becoming available for study which presents both opportunities and challenges. Two satellites recently launched to observe the sun are STEREO (Solar TErrestrial RElations Observatory), providing simultaneous views of the SUN from two different viewpoints and SDO (Solar Dynamics Observatory) which aims to study the solar atmosphere on small scales and times and in many wavelengths. The STEREO and SDO missions are providing huge volumes of data at rates of about 15 GB per day (initially it was 30 GB per day) and 1.5 terabytes per day respectively. Accessing these huge data volumes efficiently at both high spatial and high time resolutions is important to support scientific discovery but requires increasingly efficient tools to browse, locate and process specific data sets. This thesis investigates the development of new technologies for processing information contained in multiple and overlapping images of the same scene to produce images of improved quality. This area in general is titled Super Resolution (SR), and offers a technique for reducing artefacts and increasing the spatial resolution. Another challenge is to generate 3D images such as Anaglyphs from uncalibrated pairs of SR images. An automated method to generate SR images is presented here. The SR technique consists of three stages: image registration, interpolation and filtration. Then a method to produce enhanced, near real-time, 3D solar images from uncalibrated pairs of images is introduced. Image registration is an essential enabling step in SR and Anaglyph processing. An accurate point-to-point mapping between views is estimated, with multiple images registered using only information contained within the images themselves. The performances of the proposed methods are evaluated using benchmark evaluation techniques. A software application called the SOLARSTUDIO has been developed to integrate and run all the methods introduced in this thesis. SOLARSTUDIO offers a number of useful image processing tools associated with activities highly focused on solar images including: Active Region (AR) segmentation, anaglyph creation, solar limb extraction, solar events tracking and video creation.
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Dunlop, Jonathan. "Texture analysis in sonar images." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340489.
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Pfeiffer, Jennifer A. V. "Directional compensation for sidescan sonar images." Thesis, Heriot-Watt University, 2003. http://hdl.handle.net/10399/404.
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Tegeder, Troy. "Development of an efficient solar powered unmanned aerial vehicle with an onboard solar tracker /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1723.pdf.
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Tseng, David Tai Hee. "Restoration of random motion degraded sonar images." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26338.
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The problem of sonar images degraded by wave-induced random ship motion and their restoration by filtering methods is investigated. The nature of the random motion is examined in detail, and a model is set up to describe its power spectrum in terms of the sea spectrum and the ship's receptance. A sonar measurement formula and its approximated form is derived. It is shown that the approximation represents a signal with additive coloured noise process. The signal is the measured seafloor profile and is approximated by a first-order Markov process. Several filters are proposed: Kalman Filter, Recursive Least Squares Interpolating (RLSI) Filter, and Adaptive ARMA Filter. In addition, Fast Estimation Algorithm and Adaptive Algorithm are introduced to determine unknown parameters in the Kalman Filter. Simulation results are generated using these filters. Performances are found to be strongly dependent on both signal and noise characteristics, with the exception of the RLSI Filter, which is relatively independent of wind speed, the main noise parameter. Computational complexities, estimation delay and convergence rates associated with the various filters are also examined. Finally, Extended Kalman Filter and Self-Tuning Filter are proposed as possible candidates for dealing with non-stationary, time-varying degradation problem.<br>Applied Science, Faculty of<br>Electrical and Computer Engineering, Department of<br>Graduate
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Rasure, James O. "Aerosol optical depth retrieval with AVIRIS data : a test Of Tafkaa." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FRasure.pdf.
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Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2002.<br>Thesis advisor(s): Philip A. Durkee, Kurt E. Nielsen. Includes bibliographical references (p. 39-40). Also available online.
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MASSA, PAOLO. "Image reconstruction methods for Solar Orbiter STIX." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1082766.
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The Spectrometer/Telescope for Imaging X-rays (STIX) is the instrument of the Solar Orbiter mission conceived for the observation of the X-ray radiation emitted during solar flares. STIX adopts an indirect imaging technique based on the use of modulation collimators, i.e., pairs of grids mounted in front of detectors. By measuring the modulated X-ray photon flux, the telescope provides the complex values of 30 Fourier components of the angular distribution of the X-ray source, named visibilities. Hence, the imaging problem for STIX is the inverse problem of reconstructing the image of the flaring X-ray source from a sparse sampling of its Fourier transform.
In this thesis, we describe the STIX imaging concept and the image reconstruction problem both from visibilities and from photon count measurements. We present different image reconstruction techniques: the count-based Expectation Maximization (EM) algorithm, the visibility-based maximum entropy method MEM_GE and a neural network approach for parametric image reconstruction. We test these methods on synthetic STIX data and, in the case of MEM_GE, on real data provided by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). We propose a stopping rule for EM based on a predictive risk estimator. This estimator is derived by using a Poisson counterpart of Stein’s lemma for Gaussian variates. We validate the performance of the stopping rule in the case of the STIX imaging problem from synthetic data and in the case of a deconvolution inverse problem. Finally, we present the results of the STIX imaging problem from real data. We describe the first approaches of image reconstruction from semi-calibrated data, i.e., visibility amplitudes only. Then, we provide an overview of the visibility phase calibration, and we show the reconstructions from fully-calibrated visibilities obtained by using several methods, including MEM_GE and EM. The STIX reconstructions are validated by comparison with maps of the same events provided by the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory (SDO/AIA) in UV wavelengths.
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Stevens, Robert E. "Design of optimal cyclers using solar sails." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FStevens.pdf.
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Thesis (Aeronautical and Astronautical Engineer)--Naval Postgraduate School, December 2002.<br>Thesis advisor(s): I. Michael Ross, Dennis Byrnes. Includes bibliographical references (p. 119-120). Also available online.
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Mignotte, Pierre-Yves. "Content-based registration of side-scan sonar images." Thesis, Heriot-Watt University, 2008. http://hdl.handle.net/10399/2189.
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This thesis is devoted to the image registration problem of multi-modal images with applications to underwater imagery. With the advent of Autonomous Underwater Vehicles, high resolution images of the seabed can be routinely acquired. However, the relative short range of the sensors implies that a mosaicing process is necessary to produce large scale maps.
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Eriksson, Daniel. "Underwater Change Detection by Fusing Multiple Sonar Images." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-263233.
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Underwater change detection can be used for monitoring the seafloor and automatically alert when something changes on it. This could be especially useful in harbors or other critical sea-infrastructure. The idea is to constantly survey the seabed with Autonmous Underwater Vehicles (AUV) equipped with different sonars such as sidescan and multibeam sonars. The data set used, consists of two subsets were one subset is recorded before any man-made objects had been placed on the seabed, the second subsets consists of sidescan data taken after the placement. The goal of this thesis is to develop a general approach to automatically detect changes on the seabed in general, and specifically try to find the man-made objects that were placed on the seabed. In order to achieve this, the thesis will mainly analyze sidescan data. The approach considered in this thesis is based on detecting objects in the sidescan data with a template matching algorithm. Then calculating the position of the objects in a global coordinate system and store all the objects positions from the first subset in a database. After that detect the objects in the second subset and compare their positions to the database. If the position of an object in the second subset does not exists in the database, that object can be considered a new object, and thus a change detection has occurred. Different template matching methods were tested and compared to each other with two test cases. Furthermore, preprocessing of the data were tested and compared as well. In order to calculate the objects position an optimized transformation between the global coordinates and the sonar’s frame of reference were calculated, the transformation is an important part of solving the problem since it will be necessary to do it for any kind approach to change detection. The template matching proved to be difficult to work in all scenarios, where it could only successfully detect all objects in the easier test case. Furthermore, the change detection proved not to be working due to the low success rate of the template matching. However, the change detection will work if the object detection is good enough.<br>Automatisk detektering av förändringar på havsbotten kan användas för att övervaka den och meddela när en förändring sker. Detta är särskilt viktigt och användbart i hamnområden eller andra kritiska infrastrukturer som finns i haven. Idén är att ständigt kartlägga havsbotten med autonoma undervattensfarkoster (AUV från engelskans Autonomous Underwater Vehicle) utrustade med olika typer av sonars som sidescansonar och multibeamsonar. Datan som denna rapport använder sig av består till största del av två datamängder med sidescandata. Den ena datamängden består av sidescandata som samlades in innan några specifika objekt hade placerats på botten. Den andra datamängden samlades in efter att objekten hade placerats på botten. Målet med denna rapport är att utveckla ett generellt tillvägagångssätt för att automatiskt kunna detektera förändringar på havsbotten och med det specifika målet att kunna detektera objekt som har placerats på havsbotten i den andra datamängden. För att uppnå målet, kommer en strategi för att detektera objekt i sidescandatan med hjälp av template matchning att användas. Efter det så räknas objektens position i ett globalt koordinatsystem ut. Detta görs för båda datamängderna för att sedan jämföras med varandra och de objekt som bara existerar i den andra datamängden kan anses vara ett av de placerade objekten. Olika metoder för att räkna ut template matchning testas och jämförs med varandra i två testfall. Fortsättningsvis så undersöks om en förbehandling av datan kan förbättra detektering av objekten. För att kunna räkna objektens position i ett globalt koordinatsystem så behövdes en transform mellan sonars och det globala koordinatsystemet räknas ut. Transformen är viktig att hitta för att den behövs för alla strategier för att lösa problemet med detektering av förändringar på havsbotten. Template matchningen visade sig inte fungera i alla scenarier, där den bara lyckades att hitta alla objekt i ett lättare fall. Fortsättningsvis gick det inte att uppnå målet med att hitta de objekt som hade placerats ut på havsbotten på grund av att template matchningen inte gick att få generell nog att fungera på all data. Trots detta så visade sig att automatisk detektering av förändringar är möjligt om det går att hitta alla objekt i datan.
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Michalopoulos, Panayiotis. "A novel approach for the development and optimization of state-of-the-art photovoltaic devices using Silvaco." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Mar%5FMichalopoulos.pdf.
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Thesis (M.S. in Electrical Engineering and M.S. in Computer Science)--Naval Postgraduate School, March 2002.<br>Thesis advisor(s): Sherif Michael, Bret Michael, Todd Weatherford. Includes bibliographical references (p. 167-169). Also available online.
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Mitchell, Sherri Rene. "A comparative study of the prospective solar cells for NPSAT1." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FMitchell.pdf.
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Thesis (M.S. in Space Systems Operations)--Naval Postgraduate School, September 2002.<br>Thesis advisor(s): Sherif Michael, Dan Sakoda. Includes bibliographical references (p. 57-58). Also available online.
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Luce, Richard C. "Spacecraft power beaming and solar cell annealing using high-energy lasers." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FLuce.pdf.
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Thesis (M.S. in Astronautical Engineering)--Naval Postgraduate School, December 2002.<br>Thesis advisor(s): Sherif Michael, Oscar Biblarz. Includes bibliographical references (p. 75-78). Also available online.
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Laungrungthip, Nuchjira. "Sky detection in images for solar exposure prediction." Diss., Lincoln University, 2008. http://hdl.handle.net/10182/855.
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This project describes a technique for segmenting regions of sky in an image from the remainder of the image. This segmentation technique is part of a method for predicting the solar exposure at a location of interest from a set of photographs. Given the latitude and longitude of the position and the direction and field of view of the camera it is possible to calculate the position of the sun in the image at a particular time on a particular day. If that position is in a sky region of the image then the location will be exposed to the sun at that time. Critical to the success of this method for determining solar exposure is the image processing used to separate the sky from the rest of the image. This work is concerned with finding a technique which can do this for images taken under different weather conditions. The general approach to separate the sky from the rest of the image is to use the Canny edge detector and the morphology closing algorithm to find the regions in the image. The brightness and area of each region are then used to determine which regions are sky. The FloodFill algorithm is applied to identify all pixels in each sky region. An extensive empirical study is used to find a set of threshold values for the Canny edge detector, applied to the blue colour channel, which allow successful identification of the sky regions in a wide range of images. Tests using different camera filters show that they do not usefully increase the contrast between the sky and the rest of the image, when a standard compact camera is used. The work reported in this thesis shows that this approach of finding edges to identify possible sky regions works successfully on a wide range of images although there will always be situations, such as when the image is taken directly into the sun, where manual adjustment to the identified regions may be required.
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Chang, Hongsheng. "Canonical Representation of sidescan sonar images for robotics application." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291460.
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Sidescan sonar (SSS) is crucial in underwater investigation as it is cheaper and provide wider detection range. Sidescan sonars are typically mounted on Autonomous Underwater Vehicles (AUVs) or vessels. However, the pixel and it’s intensity in SSS image is not corresponding to the 3D seabed perfectly, which cause some problem to utilize SSS image for navigation and mapping. This thesis is aiming to represent the SSS image to a canonical image. The approaches considered in this thesis including model fitting in range, incident angle and beam angle on the intensity in direction across AUV traveling. Furthermore, the deconvolution in direction along AUV travelling will be applied to remove the blurry due to beam width.<br>Side-scan sonar (SSS) används ofta vid utforskning av undervattensmiljöer då det är billigare och kan läsa av breda områden. SSS är ofta monterade på autonoma undervattensfordon och fartyg. Pixlarna och deras intensitet i en SSS bild motsvarar dock inte alltid den tredimensionella havsbottnen perfekt, vilket kan leda till problem när SSS används för navigation eller kartläggning. Denna rapport representerar SSS bilder som kanoniska bilder. Metoden som beskrivs här behandlar passning av en horisontell modell i såväl avstånd, inkommande och utskickad ekolodsstrålsvinkel för att anpassa intensiteten på bilden. Avfaltning används också för att öka bildskärpan som är suddig på grund av bredden på ekolodsstrålen.
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Ling, Li. "Local Feature Correspondence on Side-Scan Sonar Seafloor Images." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-291803.
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In underwater environments, the perception and navigation systems are heavily dependent on the acoustic wave based sonar technology. Side-scan sonar (SSS) provides high-resolution, photo-realistic images of the seafloor at a relatively cheap price. These images could be considered potential candidates for place recognition and navigation of autonomous underwater vehicles (AUVs). Local feature correspondence matching, or the detection, description and matching of keypoints in overlapping images is a necessary building block for AUV navigation. Recent deep learning based research has resulted in state-of-the-art local correspondence models for camera images. For SSS images, however, deep learning based studies are limited and handcrafted methods such as SIFT and RootSIFT still dominate the field. In this study, SSS images taken from a seafloor area with bottom trawling marks were used for correspondence matching. D2-Net, a detect-and-describe VGG16 based network architecture designed for and tested on camera image correspondence was fine-tuned for SSS image correspondence. Using triplet margin ranking loss, the network was trained to simultaneously detect salient keypoints and produce similar descriptors for corresponding pixels and dissimilar descriptors for non-corresponding pixels. When evaluated on the nontrivial SSS images pairs in the test dataset, the best performing D2-Net based network was found to outperform the RootSIFT baseline in terms of number of detected keypoints, keypoint repeatability and mean matching accuracy at above 10 pixel threshold.<br>I undervattensmiljöer så är perception och navigationssystem ofta beroende av ekolodsteknik. Side scan sonar (SSS) ger högupplösta, fotorealistiska bilder av havsbottnen till en relativt låg kostnad. Dessa bilder kan användas för områdesigenkänning och navigation av autonoma undervattensfordon (AUV). Lokal kännerteckensmatchning består av detektion, beskrivning och matchning av nyckelpunkter på överlappande bilder. Detta är en viktig byggsten för AUV navigation. Nya metoder baserade på djupinlärning har varit i framkant för kännerteckensmatching av kamerabilder. Däremot är kännerteckensmatchning av SSS bilder fortfarande dominerat av traditionella metoder så som SIFT och RootSIFT. Denna rapport använder SSS bilder av havsbottnen där bottentrålning har förekommit för kännerteckensmatching. D2-Net är en detect-and-describe VGG16 baserad nätverksarkitektur designad och testad på kännerteckensmatching av kamerabilder. I denna rapport anpassas denna metod till SSS bilder. Kostnadsfunktionen använder sig av trippelmarginalsrankning så att nätverket ska kunna detektera distinkta nyckelpunkter samt producera liknande deskriptorer för matchande pixlar. Metoden utvärderades på icke-triviala SSS bildpar och uppnådde bättre resultat än RootSIFT.
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Onmek, Yadpiroon. "Fusion of sonar and stereo images for underwater archeology." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTS057/document.
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L’objectif de ce travail est de reconstruire en 3D des objets archéologiques en environnement sousmarin. Une méthode de fusion est proposée afin d’obtenir une carte 3D à partir de données sonar et du système de stéréovision sous marin.Le manuscrit est décomposé en deux parties principales : Dans une première partie, la reconstruction d’objets 3D est réalisée à partir d’un système utilisant une paire de caméras stéréoscopiques. La seconde partie utilise les données 3D de l’environnement sous marin à partir d’un sonar multifaisceaux. Ensuite, les deux informations sont mises en correspondance, données optiques et acoustiques, nécessitant de prendre en compte les différentes résolutions de ces deux capteurs.La première partie se concentre sur le système optique permettant la reconstruction 3D des objets avec la paire stéréoscopique. Le travail se fait à partir de la séquence vidéo enregistrée par des plongeurs dans des environnements dont la complexité est croissante (piscine, lac, mer). L’utilisation d’une mire de calibration sous marine permet la calibration de chaque caméra afin d’en exprimer le modèle interne, puis de déterminer les paramètres externes de rotation et de translation entre les deux caméras stéréoscopiques.La difficulté de ce travail est de construire une reconstruction 3D à partir de la séquence vidéo stéréoscopique et d’extraire les paires d’images permettant d’y parvenir.La recherche de points d’intérêts et leur mise en correspondance est réalisée en appliquant la méthode de RANSAC. La triangulation des informations pertinentes des images 2D vers le nuage de points 3D est réalisée à partir du modèle à projection centrale et l’estimation de la distance euclidienne. La texture et le rendu 3D sont ensuite obtenus par rétropropagation de ces informations dans les images 2D. La séquence temporelle des images permet une reconstruction 3D des points de l’objet en estimant les différentes transformations entre les paires d’image et en se basant sur une méthode type Structure From Motion.La seconde partie permet d’effectuer la fusion de ce modèle 3D avec la carte acoustique fournie par le sonar multifaisceaux. Afin de guider l’alignement des deux modèles, une initialisation manuelle est nécessaire, en sélectionnant des points d’intérêt sur les deux nuages de points. La mise en correspondance est finalisée par un algorithme d’Iterative Closest Points.Ce travail a permis la création d’une carte 3D multimodale utilisant un modèle 3D obtenu à partir d’une séquence vidéo et d’une carte acoustique<br>The objective of this work is to create the 3D reconstruction of the archaeologicalobjects in underwater environment. The fusion technique is present, to obtainedthe 3D maps from the optical and acoustic systems. This work is divided intotwo main parts; First, we created the 3D reconstruction of the underwater scenesfrom the optic system by using the stereo cameras. Second, we created the 3Dinformaton of the underwater environment from the acoustic system by using themultibeam sonar. And we merge the two different types of map, i.e. from the opticand acoustic, which is all the more difficult for different task because of differentresolutions.The first part focus on the optical system used, to carry out the 3D reconstruc-tion by using the stereoscopic device. The underwater video and images sequencefor this work were acquired by divers in different underwater environment such asthe sea, the lake and the pool. First using a stereo camera to take a video of a cali-bration chessboard to calibrate the parameters of the camera, the intrinsic parame-ters are estimated for each camera, and then the external parameters are estimatedto determine the rotation matrix and translation vector of the stereo camera.The aims of this work is to create 3D reconstruction from multiple images.In each images pair,the features of interest are selected and matched across im-age pairs. An additional outlier removal step is performed based on the RANSACmethod. Triangulation of the inlier features from the 2D images space into a sparse3D points cloud is done by using a pinhole camera model and Euclidean distanceestimation. Then, the texture and rendering of the 3D stereo model are processed.The tempolral sequence of images is processed into a set of local 3D reconstructionwith estimate of coordinate transformation between temporally adjacent 3D localreconstruction by using the SFM method.The second part consists of fusing the 3D model obtained previously with theacoustic map. To align the two 3D models (optical model and acoustic model), we use a first approximate registration by selecting manually few points on each cloud.To increase the accuracy of this registration, we use analgorithm ICP (IterativeClosest Point).In this work we created a 3D underwatermultimodal map performedusingglobal 3D reconstruction model and an acousticglobal map
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Tress, Andrew. "Practical classification and segmentation of large textural images." Thesis, Heriot-Watt University, 1996. http://hdl.handle.net/10399/720.
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Masek, Theodore. "Acoustic image models for navigation with forward-looking sonars." Thesis, Monterey, Calif. : Naval Postgraduate School, 2008. http://edocs.nps.edu/npspubs/scholarly/theses/2008/Dec/08Dec%5FMasek.pdf.
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Thesis (M.S. in Software Engineering)--Naval Postgraduate School, December 2008.<br>Thesis Advisor(s): Kolsch, Mathias. "December 2008." Description based on title screen as viewed on January 30, 2009. Includes bibliographical references (p. 51-52). Also available in print.
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Lin, Ying-Tsen. "Comparison and Investigation of Solar Spectral Irradiance with Solar Aspect Monitor." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64980.
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On-board the International Space Station (ISS), the Remote Atmospheric and Ionospheric Detection System (RAIDS) is a suite of limb-scanning monitors taking measurements from the extreme ultraviolet (EUV) to the near infrared (NIR). A single-scattering Rayleigh model is developed to eliminate the scattered brightness below 90 km and an inversion technique is applied on limb-scanned radiance profiles at 236.5 nm, NO (0,1) gamma band. The ISS orbit allows observations from 7:00 to 16:00 local hours over a one-month period from mid-June to mid-July of 2010 and observation of the local-time variation of NO abundance in the lower thermosphere is derived. The uniquely stable solar activity during 2010 allows the local time variation of NO to be observed with limited influence of solar variability. The comparison with a 1D model shows good agreement at altitude above 120 km, suggesting that most of the local time variation of NO is due to solar illumination, radiation, chemistry, and vertical diffusion.
Solar soft X-ray is the major driver of the variability observed in the ionospheric and thermospheric constituents at the equatorial region. Over the years measurements in these wavelengths are scarce and discrepancies lie among the existing data. The Solar Aspect Monitor (SAM) is a pinhole camera on the Extreme-ultraviolet Variability Experiment (EVE) flying on the Solar Dynamics Observatory (SDO). Every 10 seconds SAM projects the solar disk onto the CCD through a metallic filter designed to allow only solar photons shortward of 7 nm to pass. Contamination from energetic particles and out-of-band irradiance is, however, present. The broadband (BB) technique is developed for isolating the 0.1 to 7 nm integrated irradiance to produce broadband irradiance. The results agree with the zeroth-order product from the EUV SpectroPhotometer (ESP) with 25% regardless of solar activity level. Active regions in the solar atmosphere are tracked by the Apertural Progression Procedure for Light Estimate (APPLE). The photon event detection (PED) algorithm takes both BB and APPLE results as prior information to extract in-band photons. Applications of the PED products, including solar feature studies and spectral resolved irradiance, are demonstrated.<br>Ph. D.
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Andrijauskas, Fábio 1986. "Detecção de filamentos solares utilizando processamento paralelo em arquiteturas híbridas = Detection of solar filaments using parallel processing in hybrid architectures." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267769.
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Orientadores: André Leon Sampaio Gradvohl, Vitor Rafael Coluci<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia<br>Made available in DSpace on 2018-08-21T23:26:09Z (GMT). No. of bitstreams: 1
Andrijauskas_Fabio_M.pdf: 2796809 bytes, checksum: 9fd4e03f6038d482ed05a64517bb1780 (MD5)
Previous issue date: 2013<br>Resumo: A quantidade de imagens astronômicas geradas cresce diariamente, além da quantidade já obtida e armazenada. Uma grande fonte de dados são imagens solares, cujo estudo pode detectar eventos que têm a capacidade de afetar as telecomunicações, transmissão de energia elétrica e outros sistemas na Terra. Para que tais eventos sejam detectados, torna-se necessário analisar essas imagens de forma eficiente, levando em conta os aspectos de armazenamento, processamento e visualização. Agregar algoritmos de processamento de imagem e técnicas de computação de alto desempenho facilita o tratamento da informação de forma correta e em tempo reduzido. As técnicas de computação para alto desempenho utilizadas neste trabalho foram desenvolvidas para sistemas híbridos, isto é, aqueles que utilizam uma combinação de sistemas de memórias compartilhada e distribuída. Foram produzidas versões paralelas para sistemas híbridos de técnicas já estabelecidas. Além disso, novas técnicas foram propostas e testadas para esse sistema tais como o Filamento Diffusion Detection. Para avaliar a melhora no desempenho, foram feitas comparações entre as versões seriais e paralelas. Esse texto também apresenta um sistema com capacidade para armazenar, processar e visualizar as imagens solares. Em uma das técnicas de detecção de filamentos, o processo foi acelerado 120 vezes e um processo auxiliar para a detecção de áreas mais brilhantes foi 155 vezes mais rápido do que a versão serial<br>Abstract: The number of astronomical images produced grows daily, in addition to the amount already stored. Great sources of data are solar images, whose study can detect events which have the capacity to affect the telecommunications, electricity transmission and other systems on Earth. For such events being detected, it becomes necessary to treat these images in a coherent way, considering aspects of storage, processing and image visualization. Combining image processing algorithms and high performance computing techniques facilitates the handling of information accurately and in a reduced time. The techniques for high performance computing used in this work were developed for hybrid systems, which employ a combination of shared and distributed memory systems. Parallel version of some established techniques were produced for hybrid systems. Moreover, new techniques have been proposed and tested for this system. To evaluate the improvement in performance, comparisons were made between serial and parallel versions. In addition to the analysis, this text also presents a system with capacity to store, process and visualize solar images. In one of the techniques for detecting filaments, the process was accelerated 120 times. Also an auxiliary process for the detection of brighter areas was 155 times faster than the serial version<br>Mestrado<br>Tecnologia e Inovação<br>Mestre em Tecnologia
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Xie, Yiping. "Machine Learning for Inferring Depth from Side-scan Sonar Images." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-264835.
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Underwater navigation using Autonomous Underwater Vehicles (AUVs), which is significant for marine science research, highly depends on the acoustic method, sonar. Typically, AUVsare equipped with side-scan sonars and multibeam sonars at the same time since they both have their advantages and limitations. Side-scan sonars have a much wider range than multibeamsonars and at the same time are much cheaper, yet they could not provide accurate depth measurements. This thesis is aiming at investigating if a machine-interpreted method could beused to translate side-scan sonar data to multibeam data with high accuracy so that underwater navigation could be done by AUVs equipped only with side-scan sonars. The approaches considered in this thesis are based on Machine Learning methods, including generative models and discriminative models. The objective of this thesis is to investigate the feasibility of machine learning based models to infer the depth based on side-scan sonar images. Different models, including regression and Generative Adversarial Networks, are tested and compared. Different CNN based architectures such as U-Net and ResNet are tested andcompared as well. As an experiment trial, this project has already shown the ability and great potential of machine learning based methods extracting latent representations from side-scansonars and inferring the depth with reasonable accuracy. Further improvement could be madeto improve the performance and stability to be potentially verified on the AUV platforms inreal-time.<br>Undervattensnavigering med autonoma undervattensfordon (AUV från engelskans Autonomous Underwater Vehicle), är betydelsefull för marinvetenskaplig forskning, och beror starkt på vilken typ av sonar som används. Vanligtvis är AUV:er utrustade med både sidescansonar och multibeamsonar eftersom båda har sina fördelar och begränsningar. Sidescansonar har större omfång än multibeam-sonar och är samtidigt mycket billigare, men kan inte ge exakta mätningar av djupet. Detta examensarbete syftar till att undersöka om maskininlärningsmetoder skulle kunna användas för att översätta sidescandata till multibeamdata med hög noggrannhet så att undervattensnavigering skulle kunna göras av AUV:er utrustade endast med sidescansonar. Tillvägagångssättet i examensarbetet är baserat på olika maskininlärningsmetoder, däribland generativa modeller och diskriminerande modeller. Syftet är att undersöka om olika maskininlärningsbaserade modeller kan dra slutsatser om havsdjupet baserat endast på sidescandata. De modeller som testas och jämförs inkluderar regression och generativa adversativt nätverk. Även olika CNN-baserade arkitekturer som U-Net och ResNet testas och jämförs. Som ett experimentförsök har detta projekt redan visat förmågan och den stora potentialen för maskininlärningsbaserade metoder som extraherar latenta representationer från sidescansonar och kan estimera djupet med en rimlig noggrannhet. Ytterligare förbättringar skulle kunna göras för att förbättra prestanda och stabilitet som potentiellt kan verifieras på AUV-plattformar i realtid.