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Subsidence is determined in the heart of the Central Valley using Post Processed Static and Precise Point Positioning techniques / Y. Facio in Journal of applied geodesy, vol 14 n° 1 (January 2020)
[article]
Titre : Subsidence is determined in the heart of the Central Valley using Post Processed Static and Precise Point Positioning techniques Type de document : Article/Communication Auteurs : Y. Facio, Auteur ; M Mustafa Berber, Auteur Année de publication : 2020 Article en page(s) : pp 113 - 118 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Nivellement
[Termes IGN] analyse comparative
[Termes IGN] Californie (Etats-Unis)
[Termes IGN] décalage d'horloge
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données GPS
[Termes IGN] format RINEX
[Termes IGN] mesurage de phase
[Termes IGN] positionnement ponctuel précis
[Termes IGN] post-traitement GNSS
[Termes IGN] station de référence
[Termes IGN] subsidenceRésumé : (auteur) Post Processed Static (PPS) and Precise Point Positioning (PPP) techniques are not new; however, they have been refined over the decades. As such, today these techniques are offered online via GPS (Global Positioning System) data processing services. In this study, one Post Processed Static (OPUS) and one Precise Point Positioning (CSRS-PPP) technique is used to process 24 h GPS data for a CORS (Continuously Operating Reference Stations) station (P565) duration of year 2016. By analyzing the results sent by these two online services, subsidence is determined for the location of CORS station, P565, as 3–4 cm for the entire year of 2016. In addition, precision of these two techniques is determined as ∼2 cm. Accuracy of PPS and PPP results is 0.46 cm and 1.21 cm, respectively. Additionally, these two techniques are compared and variations between them is determined as 2.5 cm. Numéro de notice : A2020-042 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0043 Date de publication en ligne : 07/12/2019 En ligne : https://doi.org/10.1515/jag-2019-0043 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94513
in Journal of applied geodesy > vol 14 n° 1 (January 2020) . - pp 113 - 118[article]Postprocessing synchronization of a laser scanning system aboard a UAV / Marcela do Valle Machado in Photogrammetric Engineering & Remote Sensing, PERS, vol 85 n° 10 (October 2019)
[article]
Titre : Postprocessing synchronization of a laser scanning system aboard a UAV Type de document : Article/Communication Auteurs : Marcela do Valle Machado, Auteur ; Antonio Maria Garcia Tommaselli, Auteur ; Fernanda Magri Torres, Auteur ; Mariana Batista Campos, Auteur Année de publication : 2019 Article en page(s) : pp 753 - 763 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] décalage d'horloge
[Termes IGN] données altimétriques
[Termes IGN] données lidar
[Termes IGN] image captée par drone
[Termes IGN] méthode des moindres carrés
[Termes IGN] positionnement inertiel
[Termes IGN] post-traitement
[Termes IGN] précision altimétrique
[Termes IGN] semis de points
[Termes IGN] signal GNSS
[Termes IGN] synchronisation
[Termes IGN] télémétrie laser aéroporté
[Termes IGN] trajectoire (véhicule non spatial)Résumé : (Auteur) Synchronization of airborne laser scanning devices is a critical process that directly affects data accuracy. This process can be more challenging with low-cost airborne laser scanning (ALS) systems because some device connections from off-the-shelf sensors are less stable. An alternative to synchronization is performing a postprocessing clock correction. This article presents a technique for postprocessing synchronization (off-line) that estimates clock differences based on the correlation between the signals from the global navigation satellite system (GNSS) trajectory and the light detection and ranging (lidar) range, followed by refinement with a least-squares method. The correlation between signals was automatically estimated considering the planned flight maneuvers, in a flat terrain, to produce altimetric trajectory variations. Experiments were performed with an Ibeo LUX laser unit integrated with a NovAtel SPAN-IGM-S1 inertial navigation system that was transported by an unmanned aerial vehicle (UAV). The planimetric and altimetric accuracies of the point cloud obtained with the proposed postprocessing synchronization technique were 28 cm and 10 cm, respectively, at a flight height of 35 m. Numéro de notice : A2019-523 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.85.10.753 Date de publication en ligne : 01/10/2019 En ligne : https://doi.org/10.14358/PERS.85.10.753 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93994
in Photogrammetric Engineering & Remote Sensing, PERS > vol 85 n° 10 (October 2019) . - pp 753 - 763[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 105-2019101 SL Revue Centre de documentation Revues en salle Disponible Influence of stochastic modeling for inter-system biases on multi-GNSS undifferenced and uncombined precise point positioning / Feng Zhou in GPS solutions, vol 23 n° 3 (July 2019)
[article]
Titre : Influence of stochastic modeling for inter-system biases on multi-GNSS undifferenced and uncombined precise point positioning Type de document : Article/Communication Auteurs : Feng Zhou, Auteur ; Danan Dong, Auteur ; Xin Li, Auteur ; Harald Schuh, Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] bruit blanc
[Termes IGN] décalage d'horloge
[Termes IGN] erreur systématique inter-systèmes
[Termes IGN] estimation statistique
[Termes IGN] modèle stochastique
[Termes IGN] positionnement par GNSS
[Termes IGN] positionnement ponctuel précisRésumé : (auteur) The focus of this study is on proper modeling of the dynamics for inter-system biases (ISBs) in multi-constellation Global Navigation Satellite System (GNSS) precise point positioning (PPP) processing. First, the theoretical derivation demonstrates that the ISBs originate from not only the receiver-dependent hardware delay differences among different GNSSs but also the receiver-independent time differences caused by the different clock datum constraints among different GNSS satellite clock products. Afterward, a comprehensive evaluation of the influence of ISB stochastic modeling on undifferenced and uncombined PPP performance is conducted, i.e., random constant, random walk process, and white noise process are considered. We use data based on a 1-month period (September 2017) Multi-GNSS Experiment (MGEX) precise orbit and clock products from four analysis centers (CODE, GFZ, CNES, and WHU) and 160 MGEX tracking stations. The results demonstrate that generally, the positioning performance of PPP in terms of convergence time and positioning accuracy with the final products from CODE, CNES, and WHU is comparable among the three ISB handling schemes. However, estimating ISBs as random walk process or white noise process outperforms that as the random constant when using the GFZ products. These results indicate that the traditional estimation of ISBs as the random constant may not always be reasonable in multi-GNSS PPP processing. To achieve more reliable positioning results, it is highly recommended to consider the ISBs as random walk process or white noise process in multi-GNSS PPP processing. Numéro de notice : A2019-199 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-019-0852-0 Date de publication en ligne : 09/04/2019 En ligne : https://doi.org/10.1007/s10291-019-0852-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92654
in GPS solutions > vol 23 n° 3 (July 2019)[article]Impact of predicting real-time clock corrections during their outages on precise point positioning / Ahmed El-Mowafy in Survey review, vol 51 n° 365 (March 2019)
[article]
Titre : Impact of predicting real-time clock corrections during their outages on precise point positioning Type de document : Article/Communication Auteurs : Ahmed El-Mowafy, Auteur Année de publication : 2019 Article en page(s) : pp 183 - 192 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] décalage d'horloge
[Termes IGN] données GNSS
[Termes IGN] orbite
[Termes IGN] positionnement ponctuel précis
[Termes IGN] temps réelRésumé : (Auteur) Real-time precise point positioning (RT-PPP) is a popular positioning method for natural hazard warning systems (NHWS) such as for monitoring tsunami and earthquakes. PPP relays on the use of precise orbits and clock corrections. Hence, the positioning accuracy of RT-PPP will significantly deteriorate when experiencing a discontinuity in receiving these corrections, for instance due to a temporary modem failure. The best available approach in this case would be to use the International Global Navigation Satellite Systems Service ultra-rapid (IGU) orbits and clocks that would result in a low positioning accuracy. In this paper, we present a simplified approach to a method that we recently proposed to bridge outages in the corrections and improve the RT-PPP accuracy compared with the use of IGU. In this method, the most recent IGU orbits are used as they are compatible with the RT orbits; however, the clock corrections are predicted as a time series using a linear model with four sinusoidal terms. The prediction errors resulting from this method, age of the model and its validity period are discussed. The impact of using the proposed approach is evaluated at a number of sites of known positions by comparing its performance to using IGU orbits and clocks. Moreover, the impact of using predicted corrections is assessed in different scenarios. The experimental results proved validity of the presented approach where positioning mean RMSE of less than 20 cm was maintained during the outage period. Numéro de notice : A2019-191 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2017.1405155 Date de publication en ligne : 26/11/2017 En ligne : https://doi.org/10.1080/00396265.2017.1405155 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92635
in Survey review > vol 51 n° 365 (March 2019) . - pp 183 - 192[article]Optimization of optical clock network for the geopotential determination / Guillaume Lion (2019)
Titre : Optimization of optical clock network for the geopotential determination Type de document : Article/Communication Auteurs : Guillaume Lion , Auteur ; Isabelle Panet , Auteur ; David Coulot , Auteur ; Pacôme Delva, Auteur Editeur : Saint-Mandé : Institut national de l'information géographique et forestière - IGN (2012-) Année de publication : 2019 Conférence : AGU 2019 Fall Meeting 09/12/2019 13/12/2019 San Francisco Californie - Etats-Unis programme sans actes Projets : ChronoG2o / Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] chronométrie
[Termes IGN] décalage d'horloge
[Termes IGN] horloge optique
[Termes IGN] optimisation (mathématiques)
[Termes IGN] potentiel de pesanteur terrestreRésumé : (auteur) Clock comparisons with an uncertainty at the 10−18 in terms of relative frequency can provide a new kind of measurement to improve our knowledge of Earth’s gravity field and geoid. Instead of using state-of-the-art Earth’s gravitational field models to predict frequency shifts between distant clocks, they could permit determining geopotential differences at a centimeter-level accuracy, and question the possibility of studying geodynamic processes leading to very small vertical deformations or improve the unification of height systems. In our previous work dealing with the geopotential determination at high spatial resolution in mountainous regions, we have pointed out that clock-based geodetic observable can provide useful information at spatial scales beyond what is available from satellites and they could be used to fill areas not covered by the gravity data on the ground. Our synthetic simulations have shown that adding few clock-based potential data to a gravimetric data set can significantly improve the reconstruction of the geopotential. Therefore, it turns out there is a large variety of possible clock distribution allowing to reduce the reconstruction residuals, with different locations and number of clocks. In this work, we investigate ways to optimize clock network from a gravimetric data set in the Massif Central region in order to know where to put them to minimize the residuals and improve further the determination of the geopotential. To do that, we have used a multi-objective genetic algorithm (GA). Starting from a random initial population with different clock distributions, the algorithm selects clock locations with good chances of reproduction and reproduces the new generation of clock locations using genetic operators. The process depends on some objectives we want to reach in order to solve the optimization problem, and it is repeated several times for a given number of generations or until a solution considered as optimum is found. We show how GA can help to provide optimal solutions for a problem with a fixed and variable number of clock locations. We discuss the effect of different parameters, such as the way to define the objectives and the constrains of the problem, the quality of the clock network and the data. Numéro de notice : C2019-057 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Poster nature-HAL : Poster-avec-CL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96833 Permalink