Descripteur
Documents disponibles dans cette catégorie (4706)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
Field optical clocks and sensitivity to mass anomalies for geoscience applications / Guillaume Lion (2023)
Titre : Field optical clocks and sensitivity to mass anomalies for geoscience applications Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Gwendoline Pajot-Métivier , Auteur ; Kristel Chanard , Auteur ; Michel Diament , Auteur Editeur : Munich [Allemagne] : European Geosciences Union EGU Année de publication : 2023 Projets : ROYMAGE / Letargat, Rodolphe Conférence : EGU 2023, General Assembly 23/04/2023 28/04/2023 Vienne Autriche OA Abstracts only Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse de sensibilité
[Termes IGN] anomalie de pesanteur
[Termes IGN] chronométrie
[Termes IGN] horloge optiqueIndex. décimale : 30.60 Géodésie spatiale Résumé : (auteur) 350 years ago, the pendulum clock for astronomical observations was diverted to become an instrument for measuring gravity. The measurement of the parallax of Mars by Richer and Cassini from Cayenne and Paris showed that the period of a periodic oscillator depends on the gravity field. A link was thus established between the improvement of time measurement and the knowledge of the phenomena that govern it. Since then, the performance and nature of clocks have evolved considerably. Today, atomic clocks are used in various fields that are essential to modern society, such as the realisation of international atomic time (TAI), satellite navigation (GNSS), geodesy, the traceability of trading events, etc. In the framework of the french ANR ROYMAGE, we are interested in the contribution of a transportable optical field clock for geoscience applications by using the principle of chronometric geodesy. The idea is based on the gravitational redshift, a relativistic effect that predicts that the beat of a clock depends on the speed at which it is moving and the strength of the surrounding gravitational potential. In practice, this means that if we compare the beat of two clocks, then it is possible to directly measure a difference in gravitational potential (or a change in height) between these two clocks. This type of measurement is original because classical geodetic techniques only allow to determine the potential indirectly from gravimetric and classical levelling data. In this work, we model the gravitational signature (potential, acceleration and tensor) of a mass anomaly as a function of its geometry, depth, size and density contrast. These synthetic simulations allow us to identify which types of structures can be detected by clock comparison measurements with a relative frequency uncertainty fixed at 10-17-18-19 (i.e. a vertical sensitivity of less than 10 cm - 1 cm - 1 mm respectively). We are also interested in the spatial resolution required for a clock measurement to detect two mass anomalies depending on its orientation. Finally, we show that this new chronometric observable combined with gravimetry and gradiometry data could allow a better separation of the sources by adding an additional constraint thanks to the medium and long wavelength gravitational information it provides. Numéro de notice : C2023-003 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Autre URL associée : vers HAL Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-avec-CL DOI : 10.5194/egusphere-egu23-3646 En ligne : https://doi.org/10.5194/egusphere-egu23-3646 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103216 Improving undifferenced precise satellite clock estimation with BDS-3 quad-frequency B1I/B3I/B1C/B2a observations for precise point positioning / Guoqiang Jiao in GPS solutions, vol 27 n° 1 (January 2023)
[article]
Titre : Improving undifferenced precise satellite clock estimation with BDS-3 quad-frequency B1I/B3I/B1C/B2a observations for precise point positioning Type de document : Article/Communication Auteurs : Guoqiang Jiao, Auteur ; Shuli Song, Auteur ; Ke Su, Auteur Année de publication : 2023 Article en page(s) : n° 28 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] décalage d'horloge
[Termes IGN] données BeiDou
[Termes IGN] erreur systématique interfréquence d'horloge
[Termes IGN] fréquence multiple
[Termes IGN] horloge du satellite
[Termes IGN] positionnement ponctuel précisRésumé : (auteur) Estimates of satellite clock offsets typically employ dual-frequency undifferenced (UD) ionospheric-free (IF) observations from global network. The third-generation BeiDou Navigation Satellite System (BDS-3) can transmit B1I (1561.098 MHz), B3I (1268.52 MHz), B1C (1575.42 MHz), B2a (1176.45 MHz), B2b (1207.14 MHz) and B2ab (1191.795 MHz) signals. To make full use of the advantage of BDS-3 multi-frequency signals and improve BDS-3 service performance, we present some new quad-frequency satellite clock estimation techniques using B1I/B3I/B1C/B2a signals, which are QFIF0 model combining B1I/B3I and B1C/B2a IF observables, QFIF1 model combining the B1I/B3I, B3I/B1C and B1I/B2a IF observables, QFIF2 model combining B1I/B3I and B1I/B3I/B1C/B2a IF observables, and quad-frequency uncombined QFUC model, respectively. These new techniques only improve the performance of satellite clock estimation by fully utilizing the BDS-3 multi-frequency observations on the premise of ensuring the dual-frequency IF datum but also obtain the corresponding inter-frequency clock bias (IFCB) simultaneously. The quad-frequency satellite clock offsets are evaluated in terms of the clock offset precision, the modified Allan deviation (MDEV) and precise point positioning (PPP) performances. The new methods can improve the performances of the estimated clock offsets compared with the traditional dual-frequency IF model. The precision for the estimated clock offsets using quad-frequency satellite clock estimation models can be improved by 13–26% in terms of standard deviation (STD). The improvement of frequency stability ranges from 0 to 24%, especially for the short-term stability, which can reach 12% and 24% for B1I/B3I and B1C/B2a clock offsets, respectively. Similarly, the corresponding PPP performance has also been better improved with respect to those of using traditional dual-frequency IF clock offsets. Thus, the proposed quad-frequency satellite clock estimation techniques can be well applied into precise satellite clock estimation. Numéro de notice : A2023-025 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01364-7 Date de publication en ligne : 29/11/2022 En ligne : https://doi.org/10.1007/s10291-022-01364-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102260
in GPS solutions > vol 27 n° 1 (January 2023) . - n° 28[article]In-camera IMU angular data for orthophoto projection in underwater photogrammetry / Erica Nocerino in ISPRS Open Journal of Photogrammetry and Remote Sensing, vol 7 (January 2023)
[article]
Titre : In-camera IMU angular data for orthophoto projection in underwater photogrammetry Type de document : Article/Communication Auteurs : Erica Nocerino, Auteur ; Fabio Menna, Auteur Année de publication : 2023 Article en page(s) : n° 100027 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie
[Termes IGN] caméra numérique
[Termes IGN] carte bathymétrique
[Termes IGN] centrale inertielle
[Termes IGN] compensation par faisceaux
[Termes IGN] mesure géodésique
[Termes IGN] orthophotographie
[Termes IGN] photogrammétrie sous-marine
[Termes IGN] positionnement par GNSS
[Termes IGN] redressement différentiel
[Termes IGN] roulis
[Termes IGN] structure-from-motion
[Termes IGN] tangageRésumé : (auteur) Among photogrammetric products, orthophotos are probably the most versatile and widely used in many fields of application. In the last years, coupled with the spread of semi-automated survey and processing approaches based on photogrammetry, orthophotos have become almost a standard for monitoring the underwater environment. If on land the definition of the reference coordinate system and projection plane for the orthophoto generation is trivial, underwater it may represent a challenge. In this paper, we address the issue of defining the vertical direction and resulting horizontal plane (levelling) for the differential ortho rectification. We propose a non-invasive, contactless method based on roll and pitch angular data provided by in-camera IMU sensors and embedded in the Exif metadata of JPEG and raw image files. We show how our approach can be seamlessly integrated into automatic SfM/MVS pipelines, provide the mathematical background, and showcase real-world applications results in an underwater monitoring project. The results illustrate the effectiveness of the proposed method and, for the first time, provide a metric evaluation of the definition of the vertical direction with low-cost sensors enclosed in digital cameras directly underwater. Numéro de notice : A2023-119 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Numéro de périodique DOI : 10.1016/j.ophoto.2022.100027 Date de publication en ligne : 07/12/2022 En ligne : https://doi.org/10.1016/j.ophoto.2022.100027 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102493
in ISPRS Open Journal of Photogrammetry and Remote Sensing > vol 7 (January 2023) . - n° 100027[article]INS-assisted inter-system biases estimation and inter-system ambiguity resolution in a complex environment / Wenhao Zhao in GPS solutions, vol 27 n° 1 (January 2023)
[article]
Titre : INS-assisted inter-system biases estimation and inter-system ambiguity resolution in a complex environment Type de document : Article/Communication Auteurs : Wenhao Zhao, Auteur ; Genyou Liu, Auteur ; Ming Gao, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 3 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] centrale inertielle
[Termes IGN] erreur systématique inter-systèmes
[Termes IGN] filtre de Kalman
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] résolution d'ambiguïté
[Termes IGN] système complexe
[Termes IGN] trajet multipleRésumé : (auteur) The inter-system real-time kinematic (RTK) model in which multiple systems choose the same reference satellite uses more observations than the traditional intra-system RTK model; however, it is still difficult to accurately determine the differential inter-system biases (DISB) and inter-system ambiguity in a complex environment. We propose a tightly coupled inter-system RTK/INS model that uses the high-precision position information the inertial navigation system (INS) provides to assist in DISB estimation and inter-system ambiguity resolution. Vehicle experiments on urban roads were designed to verify the effectiveness of the method. The vehicle experiments consisted of a simulated rare satellite environment with a high cutoff elevation angle and a real complex environment with buildings and trees obscuration. A robust Kalman filter strategy is used to combat the effects of multipath and non-line-of-sight signals in real complex environments. The results indicate that with the help of INS, the standard deviation of phase and code DISB is reduced by 11 and 17%, respectively, in the simulated environment and by 33 and 18%, respectively, in the real complex environment. Compared with the intra-system RTK/INS model, inter-system RTK/INS mode 3D positioning root-mean-square error is reduced by 79% in the simulated environment and by 27% in the real complex environment. In the single-epoch mode, the ambiguity success rates of the inter-system RTK/INS model, inter-system RTK model, intra-system RTK/INS model and intra-system RTK model are 89, 74, 69 and 58%, respectively, in the simulated environment, and 68, 41, 64 and 12%, respectively, in the real complex environment. Numéro de notice : A2023-003 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-022-01347-8 Date de publication en ligne : 09/10/2022 En ligne : https://doi.org/10.1007/s10291-022-01347-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101873
in GPS solutions > vol 27 n° 1 (January 2023) . - n° 3[article]A machine learning method for Arctic lakes detection in the permafrost areas of Siberia / Piotr Janiec in European journal of remote sensing, vol 56 n° 1 (2023)
[article]
Titre : A machine learning method for Arctic lakes detection in the permafrost areas of Siberia Type de document : Article/Communication Auteurs : Piotr Janiec, Auteur ; Jakub Nowosad, Auteur ; Sbigniew Zwoliński, Auteur Année de publication : 2023 Article en page(s) : n° 2163923 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] apprentissage automatique
[Termes IGN] Arctique
[Termes IGN] classification et arbre de régression
[Termes IGN] classification par forêts d'arbres décisionnels
[Termes IGN] image Landsat-8
[Termes IGN] lac glaciaire
[Termes IGN] MERIT
[Termes IGN] modèle numérique de surface
[Termes IGN] pergélisol
[Termes IGN] Short Waves InfraRed
[Termes IGN] SibérieRésumé : (auteur) Thermokarst lakes are the main components of the vast Arctic and subarctic landscapes. These lakes can serve as geoindicators of permafrost degradation; therefore, proper lake distribution assessment methods are necessary. In this study, we compared four machine learning methods to improve existing lake detection systems. The northern part of Yakutia was selected as the study area owing to its complex environment. We used data from Landsat 8 and spectral indices to take into account the spectral characteristics of the lakes, and MERIT DEM data to take into account the topography. The lowest accuracy was found for the classification and regression trees (CART) method (overall accuracy = 81%). On the other hand, the random forests (RF) classification provided the best results (overall accuracy = 92%), and only this classification coped well in all problematic areas, such as shaded and humid areas, near steep slopes, burn scars, and rivers. The altitude and bands SWIR1 (Short wave infrared 1), SWIR2 (Short wave infrared 2), and Green were the most important. Spectral indices did not have significant impact on the classification results in the specific conditions of the thermokarst lakes environment. 17,700 lakes were identified with the total area of 271.43 km2. Numéro de notice : A2023-218 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/22797254.2022.2163923 Date de publication en ligne : 19/01/2023 En ligne : https://doi.org/10.1080/22797254.2022.2163923 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103156
in European journal of remote sensing > vol 56 n° 1 (2023) . - n° 2163923[article]PermalinkParameterisation of the GNSS troposphere tomography domain with optimisation of the nodes’ distribution / Estera Trzcina in Journal of geodesy, vol 97 n° 1 (January 2023)PermalinkPerformance tests of geodetic receivers with tilt sensors in obstructed environments using the NRTK GNSS technique / Puttipol Dumrongchai in Journal of applied geodesy, vol 17 n° 1 (January 2023)PermalinkProduction of orthophoto map using mobile photogrammetry and comparative assessment of cost and accuracy with satellite imagery for corridor mapping: a case study in Manesar, Haryana, India / Manuj Dev in Annals of GIS, vol 29 n° 1 (January 2023)PermalinkA real-time algorithm for continuous navigation in intelligent transportation systems using LiDAR-Gyroscope-Odometer integration / Tarek Hassan in Journal of applied geodesy, vol 17 n° 1 (January 2023)PermalinkDiscriminating pure Tamarix species and their putative hybrids using field spectrometer / Solomon G. Tesfamichael in Geocarto international, vol 37 n° 25 ([01/12/2022])PermalinkGalileo High Accuracy Service (HAS) ou le service de haute précision de Galileo / Bernard Flacelière in XYZ, n° 173 (décembre 2022)PermalinkHigh-precision positioning using plane-constrained RTK method in urban environments / Chen Zhuang in Navigation : journal of the Institute of navigation, vol 69 n° 4 (Fall 2022)PermalinkNavigation and Ionosphere Characterization Using High-Frequency Signals: A Performance Analysis / Yoav Baumgarten in Navigation : journal of the Institute of navigation, vol 69 n° 4 (Fall 2022)PermalinkRelevé 2D & 3D du marégraphe de Marseille / Emmanuel Clédat in XYZ, n° 173 (décembre 2022)Permalink