The Experts below are selected from a list of 2295 Experts worldwide ranked by ideXlab platform
E.p. Maillard - One of the best experts on this subject based on the ideXlab platform.
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SMC - Underwater environment restitution through sonar images and Swath Bathymetry rendering
SMC'98 Conference Proceedings. 1998 IEEE International Conference on Systems Man and Cybernetics (Cat. No.98CH36218), 1998Co-Authors: S. Daniel, D. Gueriot, E.p. MaillardAbstract:Accurately simulating sonar images and Swath Bathymetry profiles enables to render the reality of the underwater environment. This approach is strongly motivated by the operational constraints for data acquisition. Such a tool is especially attractive for tuning algorithms (i.e. detection and classification ones) according to sensors settings and sea-bottom nature and relief. Therefore, we developed such a simulator relying on acoustical ray tracing techniques tailored for considering specific underwater propagation properties (multi-path sound propagation, sound velocity profiles, adaptive ray oversampling to modelize acoustic lobe configuration). It aims at rendering data similar to what real sensors provide in a natural contest. In the proposed approach, the virtual environment gathers both static and dynamic behaviours, namely simulator inputs may be a priori known or updated all along time. Sea-ground truth is provided by either a real elevation map or fractal simulation allowing a fine macro-relief description (flat, rocky patch, rippled sea-bottom). In addition, micro-relief is modelled through sea-bed textures resulting from adequate spatial layouts of ground resolution cells. Sets of natural or manufactured bottom-laying items may be introduced using mesh descriptions (ship wreck, ...) or structured geometric primitives (anchors, pipelines...). Furthermore, the material of the previous inputs tunes their acoustic response. Taking into account carrier trajectory and attitude along time warrants multi-sensor realistic outputs. A great interest of our parallel and modular implementation is an easier incorporation in a more global rendering system. However, its interface proposes real time visualisation of the acquired environment through windows showing current sonar images, Swath Bathymetry, vehicle attitude and trajectory. Given this flexibility, a promising 3D sea-bottom and objects reconstruction method already benefit from this simulator virtual reality.
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sonar images and Swath Bathymetry simulations for environment restitution through acoustical ray tracing techniques
4th European Conference on Underwater Acoustics, 1998Co-Authors: D. Gueriot, S. Daniel, E.p. MaillardAbstract:Due to operational constraints for underwater data acquisition, simulating realistic sonar images and Swath Bathymetry profiles is crucial for tuning detection and classification algorithms according to sensors settings and sea-bottom nature and relief. Therefore, we developped such a simulator relying on acoustical ray tracing techniques tailored for considering specific underwater propagation properties. It aims at rendering data similar to what real sensors provide in a natural context. In the proposed approach, the virtual environment gathers fractal simulated or real elevation map for sea-ground truth, sets of natural or manufactured bottom-laying items and sea-bed textures resulting from adequate spatial layouts of ground resolution cells. Moreover, taking into account carrier trajectory and attitude along time warrants multi-sensor realistic outputs. Thus, sonar images generation involves specular and diffused backscattering components, multi-path sound propagation, adaptative ray oversampling to modelize acoustic lobe configuration. Concerning Swath Bathymetry charts, response of scattering cells allows to estimate elevation profiles through differential phase returns simulation. Indeed, a geometrical computation provides an ideal differential phase on which are applied various noise laws corresponding to behaviours learned from real data. A parallel conception and implementation of the algorithms give delightful results for training sonar images processings (fuzzy segmentation, detection, classification, symbolic registration, ...). Given the simulator flexibility, a promizing 3D sea-bottom and objects reconstruction method takes benefit of information issued from multiple points of view.
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Underwater environment restitution through sonar images and Swath Bathymetry rendering
SMC'98 Conference Proceedings. 1998 IEEE International Conference on Systems Man and Cybernetics (Cat. No.98CH36218), 1998Co-Authors: S. Daniel, D. Gueriot, E.p. MaillardAbstract:Accurately simulating sonar images and Swath Bathymetry profiles enables to render the reality of the underwater environment. This approach is strongly motivated by the operational constraints for data acquisition. Such a tool is especially attractive for tuning algorithms (i.e. detection and classification ones) according to sensors settings and sea-bottom nature and relief. Therefore, we developed such a simulator relying on acoustical ray tracing techniques tailored for considering specific underwater propagation properties (multi-path sound propagation, sound velocity profiles, adaptive ray oversampling to modelize acoustic lobe configuration). It aims at rendering data similar to what real sensors provide in a natural contest. In the proposed approach, the virtual environment gathers both static and dynamic behaviours, namely simulator inputs may be a priori known or updated all along time. Sea-ground truth is provided by either a real elevation map or fractal simulation allowing a fine macro-relief description (flat, rocky patch, rippled sea-bottom). In addition, micro-relief is modelled through sea-bed textures resulting from adequate spatial layouts of ground resolution cells. Sets of natural or manufactured bottom-laying items may be introduced using mesh descriptions (ship wreck, ...) or structured geometric primitives (anchors, pipelines...). Furthermore, the material of the previous inputs tunes their acoustic response. Taking into account carrier trajectory and attitude along time warrants multi-sensor realistic outputs. A great interest of our parallel and modular implementation is an easier incorporation in a more global rendering system. However, its interface proposes real time visualisation of the acquired environment through windows showing current sonar images, Swath Bathymetry, vehicle attitude and trajectory. Given this flexibility, a promising 3D sea-bottom and objects reconstruction method already benefit from this simulator virtual reality.
J.s. Bird - One of the best experts on this subject based on the ideXlab platform.
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bounding the error on bottom estimation for multi angle Swath Bathymetry sonar
Journal of the Acoustical Society of America, 2005Co-Authors: G.k. Mullins, J.s. BirdAbstract:With the recent introduction of multi‐angle Swath Bathymetry (MASB) sonar to the commercial marketplace (e.g., Benthos Inc., C3D sonar, 2004), additions must be made to the current sonar lexicon. The correct interpretation of measurements made with MASB sonar, which uses filled transducer arrays to compute angle‐of‐arrival information (AOA) from backscattered signal, is essential not only for mapping, but for applications such as statistical bottom classification. In this paper it is shown that aside from uncorrelated channel to channel noise, there exists a tradeoff between effects that govern the error bounds on bottom estimation for surfaces having shallow grazing angle and surfaces distributed along a radial arc centered at the transducer. In the first case, as the bottom aligns with the radial direction to the receiver, footprint shift and shallow grazing angle effects dominate the uncertainty in physical bottom position (surface aligns along a single AOA). Alternatively, if signal from a radial arc arrives, a single AOA is usually estimated (not necessarily at the average location of the surface). Through theoretical treatment, simulation, and field measurements, the aforementioned factors affecting MASB bottom mapping are examined. [Work supported by NSERC.]
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Bounding the error on bottom estimation for multi‐angle Swath Bathymetry sonar
Journal of the Acoustical Society of America, 2005Co-Authors: G.k. Mullins, J.s. BirdAbstract:With the recent introduction of multi‐angle Swath Bathymetry (MASB) sonar to the commercial marketplace (e.g., Benthos Inc., C3D sonar, 2004), additions must be made to the current sonar lexicon. The correct interpretation of measurements made with MASB sonar, which uses filled transducer arrays to compute angle‐of‐arrival information (AOA) from backscattered signal, is essential not only for mapping, but for applications such as statistical bottom classification. In this paper it is shown that aside from uncorrelated channel to channel noise, there exists a tradeoff between effects that govern the error bounds on bottom estimation for surfaces having shallow grazing angle and surfaces distributed along a radial arc centered at the transducer. In the first case, as the bottom aligns with the radial direction to the receiver, footprint shift and shallow grazing angle effects dominate the uncertainty in physical bottom position (surface aligns along a single AOA). Alternatively, if signal from a radial arc ...
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Analysis of Swath Bathymetry sonar accuracy
IEEE Journal of Oceanic Engineering, 2005Co-Authors: J.s. Bird, G.k. MullinsAbstract:The practical limitations of many bottom mapping sonars lie in their ability to accurately estimate the angle of arrival. This paper addresses the accuracy of angle estimation when employed to determine the location of an extended target such as the bottom. A Gaussian model is assumed for the bottom backscatter and the corresponding Cramer-Rao lower bound for the variance of the angle estimate is determined for multi-element linear arrays. The paper focuses on determining the performance of high-resolution Swath Bathymetry sonars and, therefore, concentrates on the ability to determine bottom location with short pulses. Two error mechanisms, footprint shift and uncorrelated noise, are identified as important contributors to measurement errors. The two-element interferometric sonar configuration is investigated in detail. It is shown through the use of probability distributions, the Cramer-Rao bound, and simulation that it is difficult to get a good estimate of performance through simulation alone. Performance enhancement through pre-estimation and post-estimation averaging of multiple snapshots and changes in performance with pulse length and pulse rise time are also considered. Bottom estimation performance employing multi-element arrays is compared and contrasted with that of the two-element interferometric array. It is determined that there is little benefit associated with the multi-element array in terms of angle estimation performance alone. However, when other considerations such as angle ambiguities, multiple angles of arrival, and physical shortcomings associated with practical arrays are taken into account, the multi-element array is favored.
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Improving arrays for multi-angle Swath Bathymetry
Oceans 2003. Celebrating the Past ... Teaming Toward the Future (IEEE Cat. No.03CH37492), 2003Co-Authors: J.s. Bird, S. Asadov, P. KraeutnerAbstract:Multi-angle Swath Bathymetry sonar systems use the range and estimates of the angle of signal arrival to determine bottom depth. The accuracy of angle of arrival estimates is influenced by a number of factors including noise levels, the presence of multipath arrivals, signal bandwidth, pulse length etc. Angle estimation accuracy is also affected by the integrity of the transducer array employed to receive the returning signals. This paper addresses some of the issues associated with transducer design for multi-angle Swath Bathymetry systems including inter-element crosstalk and housing interactions. Beampatterns and relative angle responses are presented for transducer arrays that show evidence of crosstalk and housing interactions. It is shown that the crosstalk and housing interactions can be reduced through the use of different inter-element materials and housing configurations. Beampatterns and relative angle responses are presented for an improved array and compared to the previous patterns and phase responses. The discussion and experimental results are limited to arrays constructed with piezo-ceramic bars resonant at 300 kHz, and intended for shallow water use.
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Multiangle Swath Bathymetry Sidescan quantitative performance analysis
OCEANS '02 MTS IEEE, 2002Co-Authors: P.h. Kraeutner, J.s. Bird, B. Charbonneau, D. Bishop, F. HeggAbstract:The recent extension of Swath Bathymetry Sidescan (SBS) sonar to Multiangle Swath Bathymetry Sidescan (MSBS) has rekindled the argument that existing performance limits (spatial resolution, Swath width and accuracy) of seafloor and water column acoustic mapping/imaging may still be improved upon. While beamformed systems continue to improve in achievable angular resolution, these systems also continue to encounter difficulties in achieving high spatial accuracy over a wide Swath due to the decreasing spatial resolution (increasing beam footprint) at increasingly shallow grazing angles. Furthermore, the large number of acoustic array elements needed for these systems and the associated instrumentation complexity make this approach both physically large and costly. As an alternative to the beamformed approach, simple and inexpensive interferometric sidescan systems have emerged and have successfully demonstrated the potential for wide Swath, high resolution seafloor mapping. However, these single angle-of-arrival measurement systems also encounter accuracy difficulties when faced with multiple concurrent arrivals (e.g. due to nontrivial seafloor features, multipath or water column targets). A multiangle-of-arrivals approach on the other hand accommodates progressively more complex scattering geometries and has been shown, even under conditions of severe multipath, to provide excellent qualitative 3D sidescan imaging results. In this paper, we consider the issue of what can be expected from MSBS systems in terms of quantitative seafloor imaging/mapping performance. The paper begins with a brief introduction to MSBS along with a discussion of its advantages and limitations relative to alternative approaches (multibeam and interferometry). Simulation experiments are then conducted for a flat seafloor with uniformly spaced 1m features (blocks). Three MSBS survey scenarios are considered, over-the side mount in shallow water (sonar 5 m above seafloor), deep tow close to the seafloor (sonar 5 m above seafloor) and over-the-side mount in deep water (sonar 40 m above seafloor). The simulations are used to produce single ping depth profiles that are in turn examined for adherence to survey accuracy requirements prescribed by the Fourth Edition International Hydrographic Organization (IHO) Standards.
Laurence Droz - One of the best experts on this subject based on the ideXlab platform.
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Eivissa slides, western Mediterranean Sea: morphology and processes
Geo-Marine Letters, 2017Co-Authors: Galderic Lastras, David Amblas, Laurence Droz, M Ivanov, Bernard Dennielou, Miquel Canals, A. AkhmetzhanovAbstract:After obtaining full-coverage Swath Bathymetry data in 1995 and very high-resolution acoustic profiles in 2002, four slides at the Balearic Margin of the Eivissa Channel in the western Mediterranean Sea were revisited in 2004 when side-scan sonar data were collected using a MAK-1M deep-towed acoustic system. These new findings, higher in resolution than those for the Swath Bathymetry, show two main features previously undetected within these submarine landslides: (1) a series of step-forming inclined and detached slabs oriented perpendicular to the slide movement and located in the uppermost part of the slides, and (2) arcuate regular positive ridges oriented also normal to the slide movement and located in the depositional lobes of some of the slides. The former are interpreted as extensional ridges, suggesting a retrogressive post-failure evolution of the slides. The latter are interpreted as compression ridges, related to plastic deformation of the sediment before movement freezing. Moreover, the new data show that fluid escape features are even more widespread in the Eivissa Channel than previously thought, dozens of new pockmarks less than 20 m in diameter having been identified.
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the nile deep sea fan preliminary results from a Swath Bathymetry survey
Marine and Petroleum Geology, 2001Co-Authors: J Mascle, Laurence Droz, Tiphaine Zitter, Gilbert Bellaiche, V Gaullier, Lies LonckeAbstract:We present and discuss a set of data, mainly Swath Bathymetry, backscatter images and a few seismic data, that have been recently recorded over large areas of the Nile deep-sea fan between water depths of 1200 and 3000 m. These data demonstrate the presence of at least three distinct morphostructural provinces where interacting sedimentary, tectonic, and salt tectonic processes control the present day morphology and the recent evolution of the major Mediterranean deep-sea fan. The role of the ongoing collision presently occurring between the continental Eratosthenes Seamount and the Cyprus Arc may have been, and still is, a determining parameter for the development of the Nile deep-sea fan.
Miquel Canals - One of the best experts on this subject based on the ideXlab platform.
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Eivissa slides, western Mediterranean Sea: morphology and processes
Geo-Marine Letters, 2017Co-Authors: Galderic Lastras, David Amblas, Laurence Droz, M Ivanov, Bernard Dennielou, Miquel Canals, A. AkhmetzhanovAbstract:After obtaining full-coverage Swath Bathymetry data in 1995 and very high-resolution acoustic profiles in 2002, four slides at the Balearic Margin of the Eivissa Channel in the western Mediterranean Sea were revisited in 2004 when side-scan sonar data were collected using a MAK-1M deep-towed acoustic system. These new findings, higher in resolution than those for the Swath Bathymetry, show two main features previously undetected within these submarine landslides: (1) a series of step-forming inclined and detached slabs oriented perpendicular to the slide movement and located in the uppermost part of the slides, and (2) arcuate regular positive ridges oriented also normal to the slide movement and located in the depositional lobes of some of the slides. The former are interpreted as extensional ridges, suggesting a retrogressive post-failure evolution of the slides. The latter are interpreted as compression ridges, related to plastic deformation of the sediment before movement freezing. Moreover, the new data show that fluid escape features are even more widespread in the Eivissa Channel than previously thought, dozens of new pockmarks less than 20 m in diameter having been identified.
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relationship between continental rise development and palaeo ice sheet dynamics northern antarctic peninsula pacific margin
Quaternary Science Reviews, 2006Co-Authors: David Amblas, Roger Urgeles, Michele Rebesco, Angelo Camerlenghi, Ferran Estrada, Antoni Calafat, Marc De Batist, Miquel Canals, John E HughesclarkeAbstract:Abstract Acquisition of Swath Bathymetry data west of the North Antarctic Peninsula (NAP), between 63°S and 66°S, and its integration with the predicted seafloor topography of Smith and Sandwell [Global seafloor topography from satellite altimetry and ship depth soundings. Science 277, 1956–1962.] reveal the links between the continental rise depositional systems and the NAP palaeo-ice sheet dynamics. The NAP Pacific margin consists of a wide continental shelf dissected by several troughs, tens of kilometres wide and long. The Biscoe Trough, which has been almost entirely surveyed with multibeam sonar, shows spectacular fan-shaped streamlining sea-floor morphologies revealing the presence of ice streams during the Last Glacial Maximum. In the study area the continental rise comprises the six northernmost sediment mounds of the NAP Pacific margin and the canyon-channel systems between them. These giant sediment mounds have developed since the early Neogene by southwest flowing bottom currents, which have redistributed along the margin the fine-grained component of the turbiditic currents flowing down canyon-channel systems. The widespread evidence of shallow slope instability within the sediment mounds has been identified from both Swath Bathymetry and topographic parametric sonar seismic reflection profiles. Bathymetric data show that the heads of all the rise canyon-channel systems coincide geographically with the mouths of the major glacial troughs on the continental shelf edge. This suggests a close genetic link between these morphological features and allows considering a glacio-sedimentary model for the western NAP outer margin seascape development. This model considers the availability of depositional space on the continental rise as the limiting factor for mound development. The depositional space, in turn, is controlled by the spacing between glacial maxima shelf-edge reaching ice streams. This model takes into account both glacial and interglacial scenarios and gives new insights on evaluating the palaeoenvironmental record of the continental rise sediment mounds.
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central and eastern bransfield basins antarctica from high resolution Swath Bathymetry data
Antarctic Science, 1997Co-Authors: Eulalia Gracia, Miquel Canals, J. Sorribas, Marcel Li Farran, Raimon PallasAbstract:For the first time complete Swath bathymetric maps of central and eastern Bransfield basins are presented at a medium scale and detailed morphological descriptions are provided. Bathymetry reveals morphological structures which provide important information about the structure, volcanism, and kinematics of these basins. The central basin is dominated by two roughly orthogonal sets of extensional faults (N065° the main set and N145° the secondary set), displays several discontinuous along-axis large volcanic cones and ridges trending about N059°, and undergoes extension roughly normal to the basin. The structure of the eastern basin has a roughly rhomboidal pattern (fault sets along N053° and N103°), displays four deep troughs and a much smaller amount of volcanism than the central basin, and is affected by extension with a significant sinistral strike-slip component.
Lies Loncke - One of the best experts on this subject based on the ideXlab platform.
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morphostructure of the egyptian continental margin insights from Swath Bathymetry surveys
Marine Geophysical Researches, 2006Co-Authors: J Mascle, Lies Loncke, Olivier Sardou, S Migeon, Laurent Camera, V GaullierAbstract:In the Eastern Mediterranean, offshore Egypt, the Nile continental margin is characterized by a large deep water turbiditic system known as the Nile Deep Sea Fan. This post-Miocene terrigenous construction covers an approximately 10 km-thick sedimentary pile, including 1–3 km of Messinian salt layers. Systematically collected Swath bathymetric data proved to be the most powerful tool to discover, describe and study many sea floor features of this sedimentary construction which reflects competition between active tectonic, sedimentary, and geochemical processes. Gravity tectonics, triggered by underlying mobile salt layers, construction of channel-levee systems, the passage of turbidite flows, sedimentary slope failures at various scales, massive mud expulsions and fluid seepages are all interfering to shape the Nile Deep Sea Fan seabed.
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An Integrated Study of the Nile Deep Sea Fan Margin
2004Co-Authors: Sébastien Migeon, Lies Loncke, Jean Mascle, Laurent CameraAbstract:D015 AN INTEGRATED STUDY OF THE NILE DEEP SEA FAN MARGIN Summary 1 Since 1998 four distinct marine geological/geophysical academic surveys (including Swath Bathymetry MCS seismic coring and recently deep dives) have brougth considerable amount of new data on the almost unknown deep Egyptian Continental Margin and particularly on the Nile Deep Sea Fan the major recent terrigenous construction within the Mediterranean Sea. This deep clastic system which shows strongly contrasted morphologies and sedimentary instabilities and contains numerous fluid escape features is made of a thick (1 to 3 km) pile of Pliocene and Quaternary sediments resting on variably thick
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the nile deep sea fan preliminary results from a Swath Bathymetry survey
Marine and Petroleum Geology, 2001Co-Authors: J Mascle, Laurence Droz, Tiphaine Zitter, Gilbert Bellaiche, V Gaullier, Lies LonckeAbstract:We present and discuss a set of data, mainly Swath Bathymetry, backscatter images and a few seismic data, that have been recently recorded over large areas of the Nile deep-sea fan between water depths of 1200 and 3000 m. These data demonstrate the presence of at least three distinct morphostructural provinces where interacting sedimentary, tectonic, and salt tectonic processes control the present day morphology and the recent evolution of the major Mediterranean deep-sea fan. The role of the ongoing collision presently occurring between the continental Eratosthenes Seamount and the Cyprus Arc may have been, and still is, a determining parameter for the development of the Nile deep-sea fan.
