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Improving the estimation of fractional-cycle biases for ambiguity resolution in precise point positioning / J. Geng in Journal of geodesy, vol 86 n° 8 (August 2012)
[article]
Titre : Improving the estimation of fractional-cycle biases for ambiguity resolution in precise point positioning Type de document : Article/Communication Auteurs : J. Geng, Auteur ; C. Shi, Auteur ; M. Ge, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 579 - 589 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] données GPS
[Termes IGN] erreur systématique
[Termes IGN] positionnement ponctuel précis
[Termes IGN] résolution d'ambiguïtéRésumé : (Auteur) Ambiguity resolution dedicated to a single global positioning system (GPS) station can improve the accuracy of precise point positioning. In this process, the estimation accuracy of the narrow-lane fractional-cycle biases (FCBs), which destroy the integer nature of undifferenced ambiguities, is crucial to the ambiguity-fixed positioning accuracy. In this study, we hence propose the improved narrow-lane FCBs derived from an ambiguity-fixed GPS network solution, rather than the original (i.e. previously proposed) FCBs derived from an ambiguity-float network solution. The improved FCBs outperform the original FCBs by ensuring that the resulting ambiguity-fixed daily positions coincide in nature with the state-of-the-art positions generated by the International GNSS Service (IGS). To verify this improvement, 1 year of GPS measurements from about 350 globally distributed stations were processed. We find that the original FCBs differ more from the improved FCBs when fewer stations are involved in the FCB estimation, especially when the number of stations is less than 20. Moreover, when comparing the ambiguity-fixed daily positions with the IGS weekly positions for 248 stations through a Helmert transformation, for the East component, we find that on 359 days of the year the daily RMS of the transformed residuals based on the improved FCBs is smaller by up to 0.8 mm than those based on the original FCBs, and the mean RMS over the year falls evidently from 2.6 to 2.2 mm. Meanwhile, when using the improved rather than the original FCBs, the RMS of the transformed residuals for the East component of 239 stations (i.e. 96.4% of all 248 stations) is clearly reduced by up to 1.6 mm, especially for stations located within a sparse GPS network. Therefore, we suggest that narrow-lane FCBs should be determined with ambiguity-fixed, rather than ambiguity-float, GPS network solutions. Numéro de notice : A2012-374 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0537-0 Date de publication en ligne : 14/12/2011 En ligne : https://doi.org/10.1007/s00190-011-0537-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31820
in Journal of geodesy > vol 86 n° 8 (August 2012) . - pp 579 - 589[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2012081 RAB Revue Centre de documentation En réserve L003 Disponible Optimal regularization for geopotential model GOCO02S by Monte Carlo methods and multi-scale representation of density anomalies / Karl Rudolf Koch in Journal of geodesy, vol 86 n° 8 (August 2012)
[article]
Titre : Optimal regularization for geopotential model GOCO02S by Monte Carlo methods and multi-scale representation of density anomalies Type de document : Article/Communication Auteurs : Karl Rudolf Koch, Auteur ; J. Brockmann, Auteur ; W.D. Schuh, Auteur Année de publication : 2012 Article en page(s) : pp 647 - 660 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse de variance
[Termes IGN] B-Spline
[Termes IGN] données GOCE
[Termes IGN] méthode de Monte-Carlo
[Termes IGN] modèle de géopotentiel
[Termes IGN] ondeletteRésumé : (Auteur) GOCO02S is a combined satellite-only geopotential model, regularized from degrees 180 to 250 of the expansion into spherical harmonics. To investigate the start of the regularization, the normal equations of GOCO02S have been used to compute additional geopotential models by regularizations beginning at degrees 160, 200, 220 and with no regularization. Three different methods are applied to determine where to start the regularization. The simplest one considers the decrease of the degree variances of the not regularized solution. The second one tests for the same solution the hypothesis that the square root of the degree variance is equal to the value computed by the estimated harmonic coefficients. If the hypothesis has to be rejected for a certain degree, the error degree variance is so large that the estimated harmonic coefficients cannot be trusted anymore so that the regularization has to start at that degree. The third method uses the density anomalies by which the disturbing potential is caused resulting from the geopotential model. The density anomalies are well suited to visualize the effects of the higher degree harmonics. In contrast to the base functions of the harmonic coefficients with global support, the density anomalies are expressed by a B-spline surface with local support. Multi-scale representations were applied and the hypotheses tested that the wavelet coefficients are equal to zero. Accepting the hypotheses means that nonsignificant wavelet coefficients were determined which lead to nonsignificant density anomalies. By comparing these anomalies for different regularizations, the degree where to start the regularization is determined. It turns out that beginning the regularization at degree 180, as was done for GOCO02S, is a correct choice. Numéro de notice : A2012-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0546-7 Date de publication en ligne : 24/02/2012 En ligne : https://doi.org/10.1007/s00190-012-0546-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31823
in Journal of geodesy > vol 86 n° 8 (August 2012) . - pp 647 - 660[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2012081 RAB Revue Centre de documentation En réserve L003 Disponible Point-to-plane registration of terrestrial laser scans / D. Grant in ISPRS Journal of photogrammetry and remote sensing, vol 72 (August 2012)
[article]
Titre : Point-to-plane registration of terrestrial laser scans Type de document : Article/Communication Auteurs : D. Grant, Auteur ; J. Bethel, Auteur ; Melba M. Crawford, Auteur Année de publication : 2012 Article en page(s) : pp 16 - 26 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] compensation par moindres carrés
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] point d'appui
[Termes IGN] superposition de données
[Termes IGN] télémétrie laser terrestreRésumé : (Auteur) The registration of pairs of Terrestrial Laser Scanning data (TLS) is an integral precursor to 3D data analysis. Of specific interest in this research work is the class of approaches that is considered to be fine registration and which does not require any targets or tie points. This paper presents a pairwise fine registration approach called P2P that is formulated using the General Least Squares adjustment model. Given some initial registration parameters, the proposed P2P approach utilizes the scanned points and estimated planar features of both scans, along with their stochastic properties. These quantities are used to determine the optimum registration parameters in the least squares sense. The proposed P2P approach was tested on both simulated and real TLS data, and experimental results showed it to be four times more accurate than the registration approach of Chen and Medioni (1991). Numéro de notice : A2012-493 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2012.05.007 En ligne : https://doi.org/10.1016/j.isprsjprs.2012.05.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31939
in ISPRS Journal of photogrammetry and remote sensing > vol 72 (August 2012) . - pp 16 - 26[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-2012061 SL Revue Centre de documentation Revues en salle Disponible Spatio-temporal MODIS EVI gap filling under cloud cover: An example in Scotland / L. Poggio in ISPRS Journal of photogrammetry and remote sensing, vol 72 (August 2012)
[article]
Titre : Spatio-temporal MODIS EVI gap filling under cloud cover: An example in Scotland Type de document : Article/Communication Auteurs : L. Poggio, Auteur ; A. Gimona, Auteur ; I. Brown, Auteur Année de publication : 2012 Article en page(s) : pp 56 - 72 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] classification pixellaire
[Termes IGN] Ecosse
[Termes IGN] image CMODIS
[Termes IGN] interpolation
[Termes IGN] krigeage
[Termes IGN] nuage
[Termes IGN] ombre
[Termes IGN] résiduRésumé : (Auteur) Time series of satellite data have an important role in the monitoring of regional and global ecosystem properties. Satellite images often present missing data due to atmospheric aerosol, clouds or other atmospheric conditions. Most methods proposed to minimise the effects of degradation and to restore signal values do not take into account the spatial and temporal correlation of the values in the pixels. The aim of this study was to propose and test a spatio-temporal interpolation method to reconstruct pixel values in MODIS data time series that are missing due to cloud cover or other image noise. The method presented and tested is an example of a hybrid Generalised Additive Model (GAM)-geostatistical space-time model, including the fitting of a smoother spatio-temporal trend and a spatial component to account for local details supported by information in covariates. The method is not limited by the type of noise or degradation of pixels values, latitude, vegetation dynamics and land uses. The application of cloud masks on the target image provided the data for a quantitative validation through the comparison between the modelled EVI values and those from the MODIS product. The method was able to restore data providing very good to adequate responses in series of simulations of missing data. The comparison of distributions showed good agreement and predictive capabilities. The spatio-temporal method always performed better and the use of kriged residuals was helpful for situations with high percentages of missing data. The spatial pattern and the local features were well preserved for cloud coverage Numéro de notice : A2012-494 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2012.06.003 En ligne : https://doi.org/10.1016/j.isprsjprs.2012.06.003 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31940
in ISPRS Journal of photogrammetry and remote sensing > vol 72 (August 2012) . - pp 56 - 72[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-2012061 SL Revue Centre de documentation Revues en salle Disponible Total least squares adjustment in partial errors-in-variables models: algorithm and statistical analysis / P. Xu in Journal of geodesy, vol 86 n° 8 (August 2012)
[article]
Titre : Total least squares adjustment in partial errors-in-variables models: algorithm and statistical analysis Type de document : Article/Communication Auteurs : P. Xu, Auteur ; J. Liu, Auteur ; C. Shi, Auteur Année de publication : 2012 Article en page(s) : pp 661 - 675 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] analyse de variance
[Termes IGN] compensation non linéaire
[Termes IGN] compensation par moindres carrés
[Termes IGN] modèle d'erreur
[Termes IGN] résidu
[Termes IGN] traitement de données GNSSRésumé : (Auteur) The weighted total least squares (TLS) method has been developed to deal with observation equations, which are functions of both unknown parameters of interest and other measured data contaminated with random errors. Such an observation model is well known as an errors-in-variables (EIV) model and almost always solved as a nonlinear equality-constrained adjustment problem. We reformulate it as a nonlinear adjustment model without constraints and further extend it to a partial EIV model, in which not all the elements of the design matrix are random. As a result, the total number of unknowns in the normal equations has been significantly reduced. We derive a set of formulae for algorithmic implementation to numerically estimate the unknown model parameters. Since little statistical results about the TLS estimator in the case of finite samples are available, we investigate the statistical consequences of nonlinearity on the nonlinear TLS estimate, including the first order approximation of accuracy, nonlinear confidence region and bias of the nonlinear TLS estimate, and use the bias-corrected residuals to estimate the variance of unit weight. Numéro de notice : A2012-378 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0552-9 Date de publication en ligne : 23/03/2012 En ligne : https://doi.org/10.1007/s00190-012-0552-9 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31824
in Journal of geodesy > vol 86 n° 8 (August 2012) . - pp 661 - 675[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2012081 RAB Revue Centre de documentation En réserve L003 Disponible An automated approach for updating land cover maps based on integrated change detection and classification methods / X. Chen in ISPRS Journal of photogrammetry and remote sensing, vol 71 (July 2012)PermalinkA fuzzy index for detecting spatiotemporal outliers / George Grekousis in Geoinformatica, vol 16 n° 3 (July 2012)PermalinkQualitative and quantitative description of multibeam echosounder systematic errors on rocky areas / Nathalie Debese in Marine geodesy, vol 35 n° 3 (July - September 2012)PermalinkThe potential of spectral mixture analysis to improve the estimation accuracy of tropical forest biomass / T.M. Basuki in Geocarto international, vol 27 n° 4 (July 2012)PermalinkVerification of 2D building outlines using oblique airborne images / A. Nyaruhuma in ISPRS Journal of photogrammetry and remote sensing, vol 71 (July 2012)PermalinkApproximation theory applied to DEM vertical accuracy assessment / X. Liu in Transactions in GIS, vol 16 n° 3 (June 2012)PermalinkOn the detectability of synthetic disturbances in FG5 absolute gravimetry data using lomb-scargle analysis / M. Orlob in Geomatica, vol 66 n° 2 (June 2012)PermalinkEvaluation of bayesian despeckling and texture extraction methods based on Gauss–Markov and auto-binomial gibbs random fields: Application to TerraSAR-X data / D. Espinoza Molina in IEEE Transactions on geoscience and remote sensing, vol 50 n° 5 Tome 2 (May 2012)PermalinkL’anticipation du changement en prospective et des changements spatiaux en géoprospective / Christine Voiron-Canicio in Espace géographique, vol 41 n° 2 (avril - juin 2012)PermalinkComparison of four line-based positional assessment methods by means of synthetic data / F. Arira-Lopez in Geoinformatica, vol 16 n° 2 (April 2012)Permalink