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Taking correlations in GPS least squares adjustments into account with a diagonal covariance matrix / Gaël Kermarrec in Journal of geodesy, vol 90 n° 9 (September 2016)
[article]
Titre : Taking correlations in GPS least squares adjustments into account with a diagonal covariance matrix Type de document : Article/Communication Auteurs : Gaël Kermarrec, Auteur ; Steffen Schön, Auteur Année de publication : 2016 Article en page(s) : pp 793 – 805 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] compensation par moindres carrés
[Termes IGN] corrélation
[Termes IGN] données GPS
[Termes IGN] estimateur
[Termes IGN] matrice de covariance
[Termes IGN] matrice diagonale
[Termes IGN] pondération
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement par GPS
[Termes IGN] régression
[Termes IGN] série temporelle
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) Based on the results of Luati and Proietti (Ann Inst Stat Math 63:673–686, 2011) on an equivalence for a certain class of polynomial regressions between the diagonally weighted least squares (DWLS) and the generalized least squares (GLS) estimator, an alternative way to take correlations into account thanks to a diagonal covariance matrix is presented. The equivalent covariance matrix is much easier to compute than a diagonalization of the covariance matrix via eigenvalue decomposition which also implies a change of the least squares equations. This condensed matrix, for use in the least squares adjustment, can be seen as a diagonal or reduced version of the original matrix, its elements being simply the sums of the rows elements of the weighting matrix. The least squares results obtained with the equivalent diagonal matrices and those given by the fully populated covariance matrix are mathematically strictly equivalent for the mean estimator in terms of estimate and its a priori cofactor matrix. It is shown that this equivalence can be empirically extended to further classes of design matrices such as those used in GPS positioning (single point positioning, precise point positioning or relative positioning with double differences). Applying this new model to simulated time series of correlated observations, a significant reduction of the coordinate differences compared with the solutions computed with the commonly used diagonal elevation-dependent model was reached for the GPS relative positioning with double differences, single point positioning as well as precise point positioning cases. The estimate differences between the equivalent and classical model with fully populated covariance matrix were below the mm for all simulated GPS cases and below the sub-mm for the relative positioning with double differences. These results were confirmed by analyzing real data. Consequently, the equivalent diagonal covariance matrices, compared with the often used elevation-dependent diagonal covariance matrix is appropriate to take correlations in GPS least squares adjustment into account, yielding more accurate cofactor matrices of the unknown. Numéro de notice : A2016-654 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE/POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0911-z En ligne : http://dx.doi.org/10.1007/s00190-016-0911-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81856
in Journal of geodesy > vol 90 n° 9 (September 2016) . - pp 793 – 805[article]Automatic extraction of road networks from GPS traces / Jia Qiu in Photogrammetric Engineering & Remote Sensing, PERS, vol 82 n° 8 (August 2016)
[article]
Titre : Automatic extraction of road networks from GPS traces Type de document : Article/Communication Auteurs : Jia Qiu, Auteur ; Ruisheng Wang, Auteur Année de publication : 2016 Article en page(s) : pp 593 - 604 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] analyse de groupement
[Termes IGN] appariement de points
[Termes IGN] compensation par moindres carrés
[Termes IGN] données GPS
[Termes IGN] extraction automatique
[Termes IGN] extraction de données
[Termes IGN] modèle de Markov
[Termes IGN] relation topologique
[Termes IGN] réseau routier
[Termes IGN] segmentationRésumé : (auteur) We propose a point segmentation and grouping method to generate road maps from GPS traces. First, we present a progressive point cloud segmentation algorithm based on Total Least Squares (TLS) line fitting. Second, we group topologically connected point clusters by the point's orientation and cluster's spatial proximity, where the topological relationship is generated using Hidden Markov Model (HMM) map matching. Finally, we refine the intersections of roads so that their geometrical and topological relationships are consistent with each other. Experimental results show that our algorithm is robust to noises and the generated road network has a high accuracy in terms of geometry and topology. Compare to the representative algorithms; the results of our new algorithm have a higher F-measure score for different matching thresholds. Numéro de notice : A2016-606 Affiliation des auteurs : non IGN Thématique : INFORMATIQUE/MATHEMATIQUE/POSITIONNEMENT Nature : Article DOI : 10.14358/PERS.82.8.593 En ligne : http://dx.doi.org/10.14358/PERS.82.8.593 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81796
in Photogrammetric Engineering & Remote Sensing, PERS > vol 82 n° 8 (August 2016) . - pp 593 - 604[article]Benefits of the third frequency signal on cycle slip correction / Xiaohong Zhang in GPS solutions, vol 20 n° 3 (July 2016)
[article]
Titre : Benefits of the third frequency signal on cycle slip correction Type de document : Article/Communication Auteurs : Xiaohong Zhang, Auteur ; Pan Li, Auteur Année de publication : 2016 Article en page(s) : pp 451 - 460 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] compensation Lambda
[Termes IGN] constellation BeiDou
[Termes IGN] glissement de cycle
[Termes IGN] positionnement ponctuel précis
[Termes IGN] récepteur trifréquenceRésumé : (Auteur) Cycle slip detection and correction are important issues when carrier phase observations are used in high-precision GNSS data processing and have, therefore, been intensively investigated. Along with the GNSS modernization, the cycle slip correction (CSC) problem has been raised to deal with more signals from multi-frequencies. We extend the geometry-based approach by integrating time-differenced pseudorange and carrier phase observations to estimate the integer number of triple-frequency cycle slips together with the receiver clock offset, ionospheric delay variations and receiver displacements. The Least-squares AMBiguity Decorrelation Adjustment method can be employed. The benefit of the third frequency observation on the cycle slip estimate is first investigated with simulation tests. The results show that adding the third frequency observation can significantly improve the model strength and that a reliable triple-frequency CSC with a theoretical success rate of higher than 99.9 % can still be achieved, even under the condition that the range or ionosphere delay variation is poorly defined. The performance of triple-frequency CSC is validated with real triple-frequency BDS data since all BDS satellites in orbit are transmitting triple-frequency signals. The results show that the fixing rate of CSC can reach 99.1 % in static precise point positioning (PPP) and 98.8 % in the kinematic case. PPP solutions with cycle slip-uncorrected and cycle slip-corrected data sets are compared to validate the correctness of triple-frequency CSC. The standard deviations of the PPP solution in east, north and vertical component, respectively, can be improved by 31.1, 30.7 and 37.6 % for static, and by 42.0, 53.8 and 39.7 % for kinematic after cycle slips are corrected. The performance of dual- and triple-frequency CSC is also compared. Results show that the performance of dual-frequency CSC is slightly worse than that of triple-frequency CSC. These results demonstrate that the performance of CSC can be significantly improved with triple-frequency observations. Numéro de notice : A2016-632 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-015-0456-2 En ligne : http://dx.doi.org/10.1007/s10291-015-0456-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81835
in GPS solutions > vol 20 n° 3 (July 2016) . - pp 451 - 460[article]A correctly weighted least squares adjustment - Part 3 Estimating standard errors in angular observations / Charles D. Ghilani in xyHt, vol 2016 n° 4 (April 2016)
[article]
Titre : A correctly weighted least squares adjustment - Part 3 Estimating standard errors in angular observations Type de document : Article/Communication Auteurs : Charles D. Ghilani, Auteur Année de publication : 2016 Article en page(s) : pp 44 - 45 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie
[Termes IGN] compensation de coordonnées
[Termes IGN] compensation par moindres carrés
[Termes IGN] écart type
[Termes IGN] estimation statistique
[Termes IGN] mesurage d'angles
[Termes IGN] mesurage électronique de distancesNuméro de notice : A2016-617 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81819
in xyHt > vol 2016 n° 4 (April 2016) . - pp 44 - 45[article]Voir aussi
- A correctly weighted least squares adjustment - Part 1 Problems from using computed standard deviations / Charles D. Ghilani in xyHt, vol 2016 n° 1 (January 2016)
- A correctly weighted least squares adjustment - Part 2 Estimating uncertainties / Charles D. Ghilani in xyHt, vol 2016 n° 2 (February 2016)
Performance analysis of triple-frequency ambiguity resolution with BeiDou observations / Xiaohong Zhang in GPS solutions, vol 20 n° 2 (April 2016)
[article]
Titre : Performance analysis of triple-frequency ambiguity resolution with BeiDou observations Type de document : Article/Communication Auteurs : Xiaohong Zhang, Auteur ; Xiyang He, Auteur Année de publication : 2016 Article en page(s) : pp 269 - 281 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] compensation Lambda
[Termes IGN] correction du trajet multiple
[Termes IGN] données BeiDou
[Termes IGN] performance
[Termes IGN] récepteur trifréquence
[Termes IGN] résolution d'ambiguïtéRésumé : (Auteur) We investigate triple-frequency ambiguity resolution performance using real BeiDou data. We test four ambiguity resolution (AR) methods which are applicable to triple-frequency observations. These are least squares ambiguity decorrelation adjustment (LAMBDA), GF-TCAR (geometry-free three-carrier ambiguity resolution), GB-TCAR (geometry-based three-carrier ambiguity resolution) and GIF-TCAR (three-carrier ambiguity resolution based on the geometry-free and ionospheric-free combination). A comparison between LAMBDA, GF-TCAR and GB-TCAR was conducted over three short baselines and two medium baselines. The results indicated that LAMBDA is optimal in both short baseline and medium baseline cases. However, the performances of GB-TCAR and LAMBDA differ slightly for short baselines. Compared with GF-TCAR, which uses the geometry-free model, the GB-TCAR using the geometry-based model improves the AR performance significantly. Compared with dual-frequency observations, the LAMBDA AR results show a significant improvement when using triple-frequency observations over short baselines. The performance of GIF-TCAR is evaluated using multi-epoch observations. The results indicated that multi-path errors on carrier phases will have a significant influence on GIF-TCAR AR results, which leads to different GIF-TCAR AR performance for different type of satellites. For GEO (Geostationary Orbit) satellites, the ambiguities can barely be correctly fixed because the multi-path errors on carrier phases are very systematic. For IGSO (Inclined Geosynchronous Orbit) and MEO (Medium Earth Orbit) satellites, when the elevation cutoff angle is set as 30°, several tens to several hundreds of epochs are needed for correctly fixing the narrow lane ambiguities. The comparison of positioning performance between dual-frequency observations and triple-frequency observations was also conducted. The results indicated that a minor improvement can be achieved by using triple-frequency observations compared with using dual-frequency observations. Numéro de notice : A2016-614 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-014-0434-0 En ligne : http://dx.doi.org/10.1007/s10291-014-0434-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81814
in GPS solutions > vol 20 n° 2 (April 2016) . - pp 269 - 281[article]A correctly weighted least squares adjustment - Part 2 Estimating uncertainties / Charles D. Ghilani in xyHt, vol 2016 n° 2 (February 2016)PermalinkCombination of GNSS and SLR measurements : contribution to the realization of the terrestrial reference frame / Sara Bruni (2016)PermalinkA correctly weighted least squares adjustment - Part 1 Problems from using computed standard deviations / Charles D. Ghilani in xyHt, vol 2016 n° 1 (January 2016)PermalinkEléments de géodésie et de la théorie des moindres carrés / Abdelmajid Ben Hadj Salem (février 2016)PermalinkSurface-based matching of 3D point clouds with variable coordinates in source and target system / Xuming Ge in ISPRS Journal of photogrammetry and remote sensing, vol 111 (January 2016)PermalinkRelative orientation dependent on dual quaternions / Qing H. Sheng in Photogrammetric record, vol 30 n° 151 (September - November 2015)PermalinkTowards a generic method for building-parcel vector data adjustment by least squares / Yann Méneroux in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol II-3 W5 (October 2015)PermalinkOutlier Detection by means of Monte Carlo Estimation including resistant Scale Estimation / Christian Marx in Journal of applied geodesy, vol 9 n° 2 (June 2015)PermalinkGPS satellite surveying / Alfred Leick (2015)PermalinkPermalink