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Measuring shallow-water bathymetric signal strength in lidar point attribute data using machine learning / Kim Lowell in International journal of geographical information science IJGIS, vol 35 n° 8 (August 2021)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 35 n° 8 (August 2021) . - pp 1592 - 1610 Titre : Measuring shallow-water bathymetric signal strength in lidar point attribute data using machine learning Type de document : Article/Communication Auteurs : Kim Lowell, Auteur ; Brian Calder, Auteur ; Anthony Lyons, Auteur Année de publication : 2021 Article en page(s) : pp 1592 - 1610 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] apprentissage automatique [Termes IGN] bathymétrie laser [Termes IGN] données lidar [Termes IGN] Extreme Gradient Machine [Termes IGN] Floride (Etats-Unis) [Termes IGN] hydrographie [Termes IGN] lever bathymétrique [Termes IGN] semis de points Résumé : (auteur) The goal of this work was to evaluate if routinely collected but seldom used airborne lidar metadata – ‘point attribute data’ (PAD) – analyzed using machine learning/artificial intelligence can improve extraction of shallow-water (less than 20 m) bathymetry from lidar point clouds. Extreme gradient boosting (XGB) models relating PAD to an existing bathymetry/not bathymetry classification were fitted and evaluated for four areas near the Florida Keys. The PAD examined include ‘pulse specific’ information such as the return intensity and PAD describing flight path consistency. The R2 values for the XGB models were between 0.34 and 0.74. Global classification accuracies were above 80% although this reflected a sometimes extreme Bathy/NotBathy imbalance that inflated global accuracy. This imbalance was mitigated by employing a probability decision threshold (PDT) that equalizes the true positive (Bathy) and true negative (NotBathy) rates. It was concluded that 1) the strength of the bathymetric signal in the PAD should be sufficient to increase accuracy of density-based lidar point cloud bathymetry extraction methods and 2) ML can successfully model the relationship between the PAD and the Bathy/NotBathy classification. A method is also presented to examine the spatial and feature-space distribution of errors that will facilitate quality assurance and continuous improvement. Numéro de notice : A2021-548 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2020.1867147 Date de publication en ligne : 30/12/2020 En ligne : https://doi.org/10.1080/13658816.2020.1867147 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98061 [article]

Extracting Shallow-Water Bathymetry from Lidar point clouds using pulse attribute data: Merging density-based and machine learning approaches / Kim Lowell in Marine geodesy, vol 44 n° 4 (July 2021)  

Public [article]  inMarine geodesy > vol 44 n° 4 (July 2021) . - pp 259 - 286 Titre : Extracting Shallow-Water Bathymetry from Lidar point clouds using pulse attribute data: Merging density-based and machine learning approaches Type de document : Article/Communication Auteurs : Kim Lowell, Auteur ; Brian Calder, Auteur Année de publication : 2021 Article en page(s) : pp 259 - 286 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] angle d'incidence [Termes IGN] apprentissage automatique [Termes IGN] bathymétrie laser [Termes IGN] classification barycentrique [Termes IGN] données lidar [Termes IGN] Extreme Gradient Machine [Termes IGN] Floride (Etats-Unis) [Termes IGN] lever bathymétrique [Termes IGN] profondeur [Termes IGN] semis de points Résumé : (auteur) To automate extraction of bathymetric soundings from lidar point clouds, two machine learning (ML1) techniques were combined with a more conventional density-based algorithm. The study area was four data “tiles” near the Florida Keys. The density-based algorithm determined the most likely depth (MLD) for a grid of “estimation nodes” (ENs). Unsupervised k-means clustering determined which EN’s MLD depth and associated soundings represented ocean depth rather than ocean surface or noise to produce a preliminary classification. An extreme gradient boosting (XGB) model was fitted to pulse return metadata – e.g. return intensity, incidence angle – to produce a final Bathy/NotBathy classification. Compared to an operationally produced reference classification, the XGB model increased global accuracy and decreased the false negative rate (FNR) – i.e. undetected bathymetry – that are most important for nautical navigation for all but one tile. Agreement between the final XGB and operational reference classifications ranged from 0.84 to 0.999. Imbalance between Bathy and NotBathy was addressed using a probability decision threshold that equalizes the FNR and the true positive rate (TPR). Two methods are presented for visually evaluating differences between the two classifications spatially and in feature-space. Numéro de notice : A2021-525 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : 10.1080/01490419.2021.1925790 Date de publication en ligne : 25/05/2021 En ligne : https://doi.org/10.1080/01490419.2021.1925790 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97964 [article]

Horizontal calibration of vessels with UASs / Casey O'Heran in Marine geodesy, vol 44 n° 2 (March 2021)  

Public [article]  inMarine geodesy > vol 44 n° 2 (March 2021) . - pp 91 - 107 Titre : Horizontal calibration of vessels with UASs Type de document : Article/Communication Auteurs : Casey O'Heran, Auteur ; Brian Calder, Auteur Année de publication : 2021 Article en page(s) : pp 91 - 107 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] balayage laser [Termes IGN] bathymétrie laser [Termes IGN] carte bathymétrique [Termes IGN] centrale inertielle [Termes IGN] données localisées des bénévoles [Termes IGN] étalonnage d'instrument [Termes IGN] modèle numérique de surface [Termes IGN] navire [Termes IGN] point d'appui [Termes IGN] réalité de terrain [Termes IGN] structure-from-motion Résumé : (auteur) Knowledge of offset vectors from vessel mounted sonars, to systems such as Inertial Measurement Units and Global Navigation Satellite Systems is crucial for accurate ocean mapping applications. Traditional survey methods, such as employing laser scanners or total stations, are used to determine professional vessel offset distances reliably. However, for vessels of opportunity that are collecting volunteer bathymetric data, it is beneficial to consider survey methods that may be less time consuming, less expensive, or which do not involve bringing the vessel into a dry dock. Thus, this article explores two alternative methods that meet this criterion for horizontally calibrating vessels. Unmanned Aircraft Systems (UASs) were used to horizontally calibrate a vessel with both Structure from Motion photogrammetry and aerial lidar while the vessel was moored to a floating dock. Estimates of the horizontal deviations from ground truth, were obtained by comparing the horizontal distances between targets on a vessel, acquired by the UAS methods, to multiple ground truth sources: a survey-grade terrestrial laser scan and fiberglass tape measurements. The investigated methods were able to achieve horizontal deviations on the order of centimeters with the use of Ground Control Points. Numéro de notice : A2021-266 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/01490419.2021.187933 Date de publication en ligne : 04/03/2021 En ligne : https://doi.org/10.1080/01490419.2021.1879330 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97320 [article]

Determination of the under water position of objects by reflectorless total stations / Štefan Rákay in Survey review, vol 53 n°376 (January 2021)  

Public [article]  inSurvey review > vol 53 n°376 (January 2021) . - pp 35 - 43 Titre : Determination of the under water position of objects by reflectorless total stations Type de document : Article/Communication Auteurs : Štefan Rákay, Auteur ; Slavomír Labant, Auteur ; Karol Bartoš, Auteur Année de publication : 2021 Article en page(s) : pp 35 - 43 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bathymétrie [Termes IGN] bathymétrie laser [Termes IGN] erreur géométrique [Termes IGN] lever bathymétrique [Termes IGN] mesurage électronique de distances [Termes IGN] objet [Termes IGN] onde électromagnétique [Termes IGN] réfraction de l'eau [Termes IGN] scène sous-marine [Termes IGN] tachéomètre électronique [Termes IGN] vitesse Résumé : (auteur) When surveying through a water surface, a distortion of several centimetres caused by the refraction and the change in the velocity of the electromagnetic waves can be observed. Therefore, neither the position nor the height of an underwater point (object), which can be seen from above the water surface, is correctly measured. The authors want to point out the magnitude of geometric errors when measuring to points under water as well as the computation of correct under water positions of points from measurement through a water layer. A practical experiment was performed for a water depth of 0.16 m. Numéro de notice : A2021-048 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2019.1683488 Date de publication en ligne : 03/11/2019 En ligne : https://doi.org/10.1080/00396265.2019.1683488 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96783 [article]

Shallow water bathymetry derived from green wavelength terrestrial laser scanner / Theodore Panagou in Marine geodesy, Vol 43 n° 5 (September 2020)  

Public [article]  inMarine geodesy > Vol 43 n° 5 (September 2020) . - pp 472 - 492 Titre : Shallow water bathymetry derived from green wavelength terrestrial laser scanner Type de document : Article/Communication Auteurs : Theodore Panagou, Auteur ; Adonis F. Velegrakis, Auteur Année de publication : 2020 Article en page(s) : pp 472 - 492 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] angle d'incidence [Termes IGN] balayage laser [Termes IGN] bathymétrie laser [Termes IGN] données lidar [Termes IGN] filtrage de points [Termes IGN] longueur d'onde [Termes IGN] profondeur [Termes IGN] réfraction [Termes IGN] semis de points [Termes IGN] surveillance du littoral [Termes IGN] télémétrie laser terrestre Résumé : (auteur) Shallow water bathymetry has proved to be a challenging task for remote sensing applications. In this work, Green-Wavelength Terrestrial Laser Scanning (GWTLS) is employed to survey nearshore bathymetry under clear atmospheric and water conditions. First, the obtained seabed points were corrected for refraction and then geo-registration, and filtering processes were exerted to obtain an accurate bathymetric surface. Terrain analysis was performed with respect to a reference surface derived from classical surveying techniques. The overall analysis has shown that the best results stem from 35° to 50° incident angles, whereas for angles higher than 65° measurements are not acceptable, although for the same angle in front and close to the instrument accuracy is considered acceptable due to the high laser power. Also, high resolution micro-topography, shallower than 1 m water depth, was managed to be captured. Systematic experimental approaches are expected to improve the GWTLS technique to detect bathymetry, which is anticipated to assist in mapping very shallow foreshore, tidal, and deltaic environments, to contribute conceptual into developing hybrid observation systems for coastal monitoring, and also to be applied in various maritime applications. Numéro de notice : A2020-482 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01490419.2020.1737602 Date de publication en ligne : 18/03/2020 En ligne : https://doi.org/10.1080/01490419.2020.1737602 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95634 [article]

sUAS-based remote rensing of river discharge using thermal particle image velocimetry and bathymetric lidar / Paul J. Kinzel in Remote sensing, vol 11 n° 19 (October-1 2019)  

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Utilisation conjointe de trains d'ondes LiDAR vert et infrarouge pour la bathymétrie des eaux de très faibles profondeurs / Tristan Allouis in Revue Française de Photogrammétrie et de Télédétection, n° 213 - 214 (janvier - avril 2017)  

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Shipborne Scanning - Simultane 3D-Vermessung des Flussbettes und der Uferbereiche am Hochrhein dirch Bathymetrie und mobiles Laserscanning / Thomas P. Kersten in Géomatique suisse, vol 111 n° 5 (mai 2013)  

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Airborne bathymetric laser scanners / Gordon Petrie in Geoinformatics, vol 14 n° 8 (01/12/2011)

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L'IGN et le SHOM primés au concours de l'Exposition internationale de cartographie 2011 / Anonyme in XYZ, n° 128 (septembre - novembre 2011)

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Utilisation conjointe de trains d'onde Lidar vert et infrarouge pour la bathymétrie des eaux de très faibles profondeurs / Tristan Allouis in Revue Française de Photogrammétrie et de Télédétection, n° 191 (Mai 2010)

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Épaisseur d'eau minimale mesurable en rivière sur fronts d'ondes lidar simulés / A. Lesaignoux in Revue Française de Photogrammétrie et de Télédétection, n° 186 (Juin 2007)

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Intérêt du lidar dans le domaine des levés / P. Monnier in Revue Française de Photogrammétrie et de Télédétection, n° 186 (Juin 2007)

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Utilisation de la technologie du lidar bathymétrique pour le suivi littoral : retour d'expériences sur le littoral méditerranéen / Y. Balouin in Revue Française de Photogrammétrie et de Télédétection, n° 186 (Juin 2007)

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Intégrer bathymétrie et LIDAR / Valerio Baiocchi in Géomatique expert, n° 55 (01/03/2007)

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