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The Influence of camera calibration on nearshore bathymetry estimation from UAV Vvdeos / Gonzalo Simarro in Remote sensing, vol 13 n° 1 (January 2021)  

Public [article]  inRemote sensing > vol 13 n° 1 (January 2021) . - n° 150 Titre : The Influence of camera calibration on nearshore bathymetry estimation from UAV Vvdeos Type de document : Article/Communication Auteurs : Gonzalo Simarro, Auteur ; Daniel Calvete, Auteur ; Theocharis A. Plomaritis, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 150 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] aberration instrumentale [Termes IGN] bathymétrie [Termes IGN] distorsion d'image [Termes IGN] eaux côtières [Termes IGN] étalonnage de chambre métrique [Termes IGN] étalonnage en vol [Termes IGN] image captée par drone [Termes IGN] lentille [Termes IGN] réalité de terrain [Termes IGN] sondeur monofaisceau Résumé : (auteur) Measuring the nearshore bathymetry is critical in coastal management and morphodynamic studies. The recent advent of Unmanned Aerial Vehicles (UAVs), in combination with coastal video monitoring techniques, allows for an alternative and low cost evaluation of the nearshore bathymetry. Camera calibration and stabilization is a critical issue in bathymetry estimation from video systems. This work introduces a new methodology in order to obtain such bathymetries, and it compares the results to echo-sounder ground truth data. The goal is to gain a better understanding on the influence of the camera calibration and stabilization on the inferred bathymetry. The results show how the proposed methodology allows for accurate evaluations of the bathymetry, with overall root mean square errors in the order of 40 cm. It is shown that the intrinsic calibration of the camera, related to the lens distortion, is the most critical aspect. Here, the intrinsic calibration that was obtained directly during the flight yields the best results. Numéro de notice : A2021-076 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs13010150 date de publication en ligne : 05/01/2021 En ligne : https://doi.org/10.3390/rs13010150 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96814 [article]

Intercomparisons of precipitable water vapour derived from radiosonde, GPS and sunphotometer observations / Shaoqi Gong in Geodetski vestnik, vol 64 n° 4 (December 2020 - February 2021)  

Public [article]  inGeodetski vestnik > vol 64 n° 4 (December 2020 - February 2021) . - pp 562 - 577 Titre : Intercomparisons of precipitable water vapour derived from radiosonde, GPS and sunphotometer observations Type de document : Article/Communication Auteurs : Shaoqi Gong, Auteur ; Wenqin Chen, Auteur ; Cunjie Zhang, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 562 - 577 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] atmosphère terrestre [Termes IGN] coefficient de corrélation [Termes IGN] photomètre [Termes IGN] photométrie [Termes IGN] positionnement par GNSS [Termes IGN] précipitation [Termes IGN] radiosondage [Termes IGN] station d'observation [Termes IGN] valeur aberrante [Termes IGN] vapeur d'eau Résumé : (Auteur) The atmospheric precipitable water vapour (PWV) plays a crucial role in the hydrological cycle and energy transfer on a global scale. Radiosonde (RS), sunphotometer (SP) and GPS (as well as broader GNSS) receivers have gradually been the principal instruments for ground-based PWV observation. This study first co-locates the observation stations configured the three instruments in the globe and in three typical latitudinal climatic regions respectively, then the PWV data from the three instruments are matched each other according to the observing times. After the outliers are removed from the matched data pairs, the PWV intercomparisons for any two instruments are performed. The results show that the PWV estimates from any two instruments have a good agreement with very high correlation coefficients. The latitude and climate have no significant influence on the PWV measurements from the three instruments, indicating that the instruments are very stable and depend on their performance. The PWV differences of any two instruments display the normal distribution, indicating non-systematic biases among the two PWV datasets. The relative differences between SP and GPS are the smallest, the middle between SP and RS, and those between GPS and RS are the largest. This study will be useful to promote GPS (GNSS) and SP PWV to be a substitute for RS PWV as a benchmark because of their high temporal resolutions. Numéro de notice : A2020-778 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.15292/geodetski-vestnik.2020.04.562-577 En ligne : http://www.geodetski-vestnik.com/en/2020-4 Format de la ressource électronique : URL bulletin Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96709 [article]

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Improved depth estimation for occlusion scenes using a light-field camera / Changkun Yang in Photogrammetric Engineering & Remote Sensing, PERS, vol 86 n° 7 (July 2020)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 86 n° 7 (July 2020) . - pp 443-456 Titre : Improved depth estimation for occlusion scenes using a light-field camera Type de document : Article/Communication Auteurs : Changkun Yang, Auteur ; Zhaoqin Liu, Auteur ; Kaichang Di, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : pp 443-456 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] approche pixel [Termes IGN] caméra numérique [Termes IGN] détection de partie cachée [Termes IGN] disparité [Termes IGN] effet de profondeur cinétique [Termes IGN] lentille [Termes IGN] méthode de centrage [Termes IGN] rayonnement lumineux [Termes IGN] reconstruction 3D Résumé : (Auteur) With the development of light-field imaging technology, depth estimation using light-field cameras has become a hot topic in recent years. Even through many algorithms have achieved good performance for depth estimation using light-field cameras, removing the influence of occlusion, especially multi-occlusion, is still a challenging task. The photo-consistency assumption does not hold in the presence of occlusions, which makes most depth estimation of light-field imaging unreliable. In this article, a novel method to handle complex occlusion in depth estimation of light-field imaging is proposed. The method can effectively identify occluded pixels using a refocusing algorithm, accurately select unoccluded views using the adaptive unoccluded-view identification algorithm, and then improve the depth estimation by computing the cost volumes in the unoccluded views. Experimental results demonstrate the advantages of our proposed algorithm compared with conventional state-of-the art algorithms on both synthetic and real light-field data sets. Numéro de notice : A2020-383 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.86.7.443 date de publication en ligne : 01/07/2020 En ligne : https://doi.org/10.14358/PERS.86.7.443 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95430 [article]

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Robust pose estimation and calibration of catadioptric cameras with spherical mirrors / Sagi Filin in Photogrammetric Engineering & Remote Sensing, PERS, vol 86 n° 1 (January 2020)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 86 n° 1 (January 2020) . - pp 33 - 44 Titre : Robust pose estimation and calibration of catadioptric cameras with spherical mirrors Type de document : Article/Communication Auteurs : Sagi Filin, Auteur ; Grigory Ilizirov, Auteur ; Bashar Elnashef, Auteur Année de publication : 2020 Article en page(s) : pp 33 - 44 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] estimation de pose [Termes IGN] étalonnage de chambre métrique [Termes IGN] flux lumineux [Termes IGN] lentille [Termes IGN] méthode robuste [Termes IGN] miroir [Termes IGN] reconstruction 3D [Termes IGN] sphère [Termes IGN] trilatération Résumé : (Auteur) Catadioptric cameras broaden the field of view and reveal otherwise occluded object parts. They differ geometrically from central-perspective cameras because of light reflection from the mirror surface. To handle these effects, we present new pose-estimation and reconstruction models for imaging through spherical mirrors. We derive a closed-form equivalent to the collinearity principle via which three methods are established to estimate the system parameters: a resection-based one, a trilateration-based one that introduces novel constraints that enhance accuracy, and a direct and linear transform-based one. The estimated system parameters exhibit improved accuracy compared to the state of the art, and analysis shows intrinsic robustness to the presence of a high fraction of outliers. We then show that 3D point reconstruction can be performed at accurate levels. Thus, we provide an in-depth look into the geometrical modeling of spherical catadioptric systems and practical enhancements of accuracies and requirements to reach them. Numéro de notice : A2020-050 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.86.1.33 date de publication en ligne : 01/01/2020 En ligne : https://doi.org/10.14358/PERS.86.1.33 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94535 [article]

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Geometric model and assessment of a dual‐fisheye imaging system / Mariana Batista Campos in Photogrammetric record, vol 33 n° 162 (June 2018)  

Public [article]  inPhotogrammetric record > vol 33 n° 162 (June 2018) . - pp 243 - 263 Titre : Geometric model and assessment of a dual‐fisheye imaging system Type de document : Article/Communication Auteurs : Mariana Batista Campos, Auteur ; Antonio Maria Garcia Tommaselli, Auteur ; José Marcato, Auteur ; Eija Honkavaara, Auteur Année de publication : 2018 Article en page(s) : pp 243 - 263 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] chambre panoramique [Termes IGN] compensation par faisceaux [Termes IGN] contrainte de stabilité [Termes IGN] élément d'orientation interne [Termes IGN] étalonnage de chambre métrique [Termes IGN] lentille [Termes IGN] panorama sphérique Résumé : (Auteur) This paper presents a technique for the calibration of a 360° dual imaging system (Ricoh Theta S) composed of two cameras with fisheye lenses specially mounted in a common structure. The experiments are based on calibration with a bundle adjustment using the equidistant fisheye lens model and relative orientation stability constraints, such as distance, base elements and rotation matrix between individual cameras’ coordinate systems. As a result, an equidistant mathematical model using the Conrady–Brown lens distortion model was shown to be suitable for estimating the interior and relative orientation parameters of the Ricoh Theta S. The main contribution presented in this work is a simultaneous bundle adjustment approach with stability constraints on base elements and rotation matrix angles, which achieved accuracies comparable with conventional photogrammetric calibration with perspective cameras. Numéro de notice : A2018-225 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/phor.12240 date de publication en ligne : 15/05/2018 En ligne : https://doi.org/10.1111/phor.12240 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90046 [article]

Baseline and triangulation geometry in a standard plenoptic camera / Christopher Hahne in International journal of computer vision, vol 126 n° 1 (January 2018)  

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Precipitable water vapour content from ESR/SKYNET sun–sky radiometers : validation against GNSS/GPS and AERONET over three different sites in Europe / Monica Campanelli in Atmospheric measurement techniques, vol 11 n° 1 (January 2018)  

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Integrated precipitable water from GPS observations and cimel sunphotometer measurements at CGO Belsk / Michal Kruczyk in Reports on geodesy and geoinformatics, vol 103 n° 1 (June 2017)  

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Utilisation d’une source laser pulsée à haute energie comme source acoustique large bande en milieu liquide / Jean-Pierre Sessarego in Traitement du signal, vol 33 n° 1 (2016-1)

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Study and development of a laser based alignment system for the compact linear collider / Guillaume Stern (2016)  

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Ocular robotics : The world's most dynamic eye / Ocular robotics in GIM international [en ligne], vol 29 n° 12 (December 2015)

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Un télémètre transportable de résolution submicrométrique / Shéhérazade Azouigui in Revue française de métrologie, vol 2015 n° 37 (janvier - mars 2015) 

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Plusieurs scanners pour surveiller une rampe / Vincent Barras in Géomatique suisse, vol 112 n° 2 (01/02/2014)  

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Développement d'un accéléromètre atomique compact pour la gravimétrie de terrain et la navigation inertielle / Jean Lautier-Blisson (2014)  

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Itinéraires de la précision / Martina Schiavon (2013)

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