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A new relationship between the quality criteria for geodetic networks / Ivandro Klein in Journal of geodesy, vol 93 n° 4 (April 2019)
[article]
Titre : A new relationship between the quality criteria for geodetic networks Type de document : Article/Communication Auteurs : Ivandro Klein, Auteur ; Marcelo Tomio Matsuoka, Auteur ; Matheus Pereira Guzatto, Auteur ; Felipe Geremia-Nievinski, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 529 - 544 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] erreur systématique
[Termes IGN] fiabilité des données
[Termes IGN] incertitude géométrique
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] réseau géodésique planimétrique
[Termes IGN] valeur aberranteRésumé : (Auteur) The goal of this paper is to present a new relationship between the quality criteria for geodetic networks. The quality criteria described here are fourfold: positional uncertainty of network points, considering both bias and precision (at a given confidence level); the maximum allowable number of undetected outliers; the level of reliability and its homogeneity for the observations; and the minimum power of the data snooping test procedure for multiple alternative hypotheses. The highlights consist of the use of advanced concepts, such as reliability measures for multiple outliers and the power of the test for multiple alternative hypotheses (instead of the single outlier and/or the single alternative hypothesis case); and a sequential computational procedure, wherein the quality criteria are mathematically related, instead of being treated as separate criteria. Its practical application is demonstrated numerically in the design of a real horizontal network. A satisfactory performance was achieved by means of simulations. Furthermore, Monte Carlo experiments were conducted to verify the power of the test and the positional uncertainty following the approach proposed. Results provide empirical evidence that the quality criteria present realistic outputs. Numéro de notice : A2019-156 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1181-8 Date de publication en ligne : 04/08/2018 En ligne : https://doi.org/10.1007/s00190-018-1181-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92495
in Journal of geodesy > vol 93 n° 4 (April 2019) . - pp 529 - 544[article]Refining ionospheric delay modeling for undifferenced and uncombined GNSS data processing / Qile Zhao in Journal of geodesy, vol 93 n° 4 (April 2019)
[article]
Titre : Refining ionospheric delay modeling for undifferenced and uncombined GNSS data processing Type de document : Article/Communication Auteurs : Qile Zhao, Auteur ; YinTong Wang, Auteur ; Shengfeng Gu, Auteur ; Fu Zheng, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 545 - 560 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] modèle déterministe
[Termes IGN] modèle ionosphérique
[Termes IGN] modèle stochastique
[Termes IGN] positionnement ponctuel précis
[Termes IGN] retard ionosphèrique
[Vedettes matières IGN] Traitement de données GNSSRésumé : (Auteur) To access the full capabilities of multi-frequency signals from the modernized GPS, GLONASS and newly deployed BDS, Galileo, the undifferenced and uncombined observable model in which the individual signal of each frequency is treated as independent observable has drawn increasing interest in GNSS community. The ionosphere delay is the major issue in the undifferenced and uncombined observable model. Though several ionosphere delay parameterization approaches have been promoted, we argue that the functional model with only deterministic characteristic may not follow the irregular spatial and temporal variations. On the contrary, when the ionosphere delay is estimated as random walk or even white noise with only stochastic characteristic, the ionosphere terms turn out to be non-estimable or not sensitive to their absolute value. In the authors’ previous study, we have developed the deterministic plus stochastic ionosphere model, denoted as DESIGN, in which the deterministic part expressed with second-order polynomial is estimated as piece-wise constant over 5 min and the stochastic part is estimated as random walk with constrains derived based on statistics of 4 weeks data in 2010. In this contribution, we further model the deterministic part with Fourier series and update the variogram of the stochastic part accordingly based on two-year data collected by about 150 stations. From the statistic studies, it is concluded that the main frequency components are identical for different coefficients, different stations, as well as different ionosphere activity status, but with varying amplitude. Thus, in the Fourier series expression of the deterministic part, we fix the frequency and estimate the amplitude as daily constant unknowns. Concerning the stochastic component, the variation of variogram is both, geomagnetic latitude and ionosphere activity status dependent. Thus, we use the Gaussian function and Epstein function to model the variation of geomagnetic latitude and ionosphere activity status, respectively. Based on the undifferenced and uncombined observable model with ionosphere constrained with DESIGN, both dual-frequency and single-frequency PPP are carried out to demonstrate its efficiency with three-month data collected in 2010, 2014, and 2017 with different ionosphere activity status. The experimental results suggest that compared with ionosphere-free model and our previous method, the averaged 3D improvement of our new method is 17.8 and 7.6% for dual-frequency PPP, respectively. While for single-frequency PPP, the averaged 3D improvement is 37.0 and 14%, respectively. Numéro de notice : A2019-157 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-018-1180-9 Date de publication en ligne : 31/07/2019 En ligne : https://doi.org/10.1007/s00190-018-1180-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92496
in Journal of geodesy > vol 93 n° 4 (April 2019) . - pp 545 - 560[article]The stochastic model for Global Navigation Satellite Systems and terrestrial laser scanning observations: A proposal to account for correlations in least squares adjustment / Gaël Kermarrec in Journal of applied geodesy, vol 13 n° 2 (April 2019)
[article]
Titre : The stochastic model for Global Navigation Satellite Systems and terrestrial laser scanning observations: A proposal to account for correlations in least squares adjustment Type de document : Article/Communication Auteurs : Gaël Kermarrec, Auteur ; Ingo Neumann, Auteur ; Hamza Alkhatib, Auteur ; Steffen Schön, Auteur Année de publication : 2019 Article en page(s) : pp 93 - 104 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] analyse de variance
[Termes IGN] compensation par faisceaux
[Termes IGN] compensation par moindres carrés
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] matrice
[Termes IGN] modèle stochastiqueRésumé : (Auteur) The best unbiased estimates of unknown parameters in linear models have the smallest expected mean-squared errors as long as the residuals are weighted with their true variance–covariance matrix. As this condition is rarely met in real applications, the least-squares (LS) estimator is less trustworthy and the parameter precision is often overoptimistic, particularly when correlations are neglected. A careful description of the physical and mathematical relationships between the observations is, thus, necessary to reach a realistic solution and unbiased test statistics. Global Navigation Satellite Systems and terrestrial laser scanners (TLS) measurements show similarities and can be both processed in LS adjustments, either for positioning or deformation analysis. Thus, a parallel between stochastic models for Global Navigation Satellite Systems observations proposed previously in the case of correlations and functions for TLS range measurements based on intensity values can be drawn. This comparison paves the way for a simplified way to account for correlations for a use in LS adjustment. Numéro de notice : A2019-144 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2018-0019 Date de publication en ligne : 24/01/2019 En ligne : https://doi.org/10.1515/jag-2018-0019 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92471
in Journal of applied geodesy > vol 13 n° 2 (April 2019) . - pp 93 - 104[article]Vertical ionospheric delay estimation for single-receiver operation / Ahmed Elsayed in Journal of applied geodesy, vol 13 n° 2 (April 2019)
[article]
Titre : Vertical ionospheric delay estimation for single-receiver operation Type de document : Article/Communication Auteurs : Ahmed Elsayed, Auteur ; Ahmed Sedeek, Auteur ; Mohamed Doma, Auteur ; Mostafa Rabah, Auteur Année de publication : 2019 Article en page(s) : pp 81 - 92 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] estimation statistique
[Termes IGN] Matlab
[Termes IGN] mesurage de phase
[Termes IGN] méthode des moindres carrés
[Termes IGN] positionnement ponctuel précis
[Termes IGN] récepteur bifréquence
[Termes IGN] retard ionosphèrique
[Termes IGN] teneur verticale totale en électronsRésumé : (Auteur) An apparent delay is occurred in GPS signal due to both refraction and diffraction caused by the atmosphere. The second region of the atmosphere is the ionosphere. The ionosphere is significantly related to GPS and the refraction it causes in GPS signal is considered one of the main source of errors which must be eliminated to determine accurate positions. GPS receiver networks have been used for monitoring the ionosphere for a long time.
The ionospheric delay is the most predominant of all the error sources. This delay is a function of the total electron content (TEC). Because of the dispersive nature of the ionosphere, one can estimate the ionospheric delay using the dual frequency GPS.
In the current research our primary goal is applying Precise Point Positioning (PPP) observation for accurate ionosphere error modeling, by estimating Ionosphere delay using carrier phase observations from dual frequency GPS receiver. The proposed algorithm was written using MATLAB and was named VIDE program.
The proposed Algorithm depends on the geometry-free carrier-phase observations after detecting cycle slip to estimates the ionospheric delay using a spherical ionospheric shell model, in which the vertical delays are described by means of a zenith delay at the station position and latitudinal and longitudinal gradients.
Geometry-free carrier-phase observations were applied to avoid unwanted effects of pseudorange measurements, such as code multipath. The ionospheric estimation in this algorithm is performed by means of sequential least-squares adjustment.
Finally, an adaptable user interface MATLAB software are capable of estimating ionosphere delay, ambiguity term and ionosphere gradient accurately.Numéro de notice : A2019-143 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2018-0041 Date de publication en ligne : 04/01/2019 En ligne : https://doi.org/10.1515/jag-2018-0041 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92470
in Journal of applied geodesy > vol 13 n° 2 (April 2019) . - pp 81 - 92[article]Application de la loi de Benford au contrôle de qualité des modèles numériques de terrain / Laurent Polidori in XYZ, n° 158 (mars 2019)
[article]
Titre : Application de la loi de Benford au contrôle de qualité des modèles numériques de terrain Type de document : Article/Communication Auteurs : Laurent Polidori, Auteur ; Mhamad El Hage, Auteur Année de publication : 2019 Article en page(s) : pp 13 - 16 Note générale : bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] altitude
[Termes IGN] contrôle qualité
[Termes IGN] distribution de Benford
[Termes IGN] distribution, loi de
[Termes IGN] logarithme
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] modèle numérique de terrain
[Termes IGN] pente
[Termes IGN] qualité des donnéesRésumé : (auteur) La loi de Benford fait le constat empirique d’une régularité dans la distribution statistique du premier chiffre dans de nombreuses séries de nombres (géographie, sport, économie, etc.). Elle a été utilisée pour détecter des fraudes comptables ou électorales. Dans le même esprit, nous avons cherché à l’utiliser comme critère de vraisemblance pour évaluer la qualité des modèles numériques de terrain. Les métriques considérées sont l’altitude, la pente et l’ordre de Strahler. Numéro de notice : A2019-081 Affiliation des auteurs : non IGN Thématique : IMAGERIE/MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92218
in XYZ > n° 158 (mars 2019) . - pp 13 - 16[article]Réservation
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