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On the topographic bias and density distribution in modelling the geoid and orthometric heights / Lars E. Sjöberg in Journal of geodetic science, vol 8 n° 1 (January 2018)
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Titre : On the topographic bias and density distribution in modelling the geoid and orthometric heights Type de document : Article/Communication Auteurs : Lars E. Sjöberg, Auteur Année de publication : 2018 Article en page(s) : pp 30 - 33 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] altitude orthométrique
[Termes IGN] analyse numérique
[Termes IGN] erreur systématique
[Termes IGN] géoïde
[Termes IGN] incertitude géométrique
[Termes IGN] montagneRésumé : (Auteur) It is well known that the success in precise determinations of the gravimetric geoid height (N) and the orthometric height (H) rely on the knowledge of the topographic mass distribution. We show that the residual topographic bias due to an imprecise information on the topographic density is practically the same for N and H, but with opposite signs. This result is demonstrated both for the Helmert orthometric height and for a more precise orthometric height derived by analytical continuation of the external geopotential to the geoid. This result leads to the conclusion that precise gravimetric geoid heights cannot be validated by GNSS-levelling geoid heights in mountainous regions for the errors caused by the incorrect modelling of the topographic mass distribution, because this uncertainty is hidden in the difference between the two geoid estimators. Numéro de notice : A2018-614 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jogs-2018-0004 Date de publication en ligne : 02/03/2018 En ligne : https://doi.org/10.1515/jogs-2018-0004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92662
in Journal of geodetic science > vol 8 n° 1 (January 2018) . - pp 30 - 33[article]A posteriori bias correction of three models used for environmental reporting / Bogdan M. Strimbu in Forestry, an international journal of forest research, vol 91 n° 1 (January 2018)
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Titre : A posteriori bias correction of three models used for environmental reporting Type de document : Article/Communication Auteurs : Bogdan M. Strimbu, Auteur ; Alexandru Amarioarei, Auteur ; John Paul McTague, Auteur ; Mihaela M. Paun, Auteur Année de publication : 2018 Article en page(s) : pp 49 - 62 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Statistiques
[Termes IGN] correction
[Termes IGN] erreur systématique
[Termes IGN] Louisiane (Etats-Unis)
[Termes IGN] modèle mathématique
[Termes IGN] Oregon (Etats-Unis)
[Termes IGN] Pinus ponderosa
[Termes IGN] Pseudotsuga menziesii
[Termes IGN] résidu
[Termes IGN] Roumanie
[Termes IGN] Texas (Etats-Unis)Résumé : (Auteur) A plethora of forest models were developed by transforming the dependent variable, which introduces bias if appropriate corrections are not applied when back-transformed. Many recognized models are still biased and the original data sets are no longer available, which suggests ad hoc bias corrections. The present research presents a procedure for bias correction in the absence of needed information from summary statistics. Additionally, we developed a realistic correction of the square root transformation based on a truncated normal distribution. The transformations considered in this study are the logarithm, the square root and arcsine square root. Using simulated data we found that uncorrected back-transformation created biases by as much as 100 percent. The generated data revealed that depending on available information, that bias can still be present after correction. In addition to generated data we corrected the site index of Douglas-fir and ponderosa pine in Oregon USA, tree volume of 27 species from Romania, stand merchantable volume for longleaf pine in Louisiana and East Texas USA, and canopy fuel weight in Washington USA. Using only the available information, the unbiased back-transformed estimates can change from ≤1 percent (i.e. the site index and canopy fuel weight) to ≥⅓ (tree and stand volume). Numéro de notice : A2018-631 Affiliation des auteurs : non IGN Thématique : FORET/MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/forestry/cpx032 Date de publication en ligne : 10/08/2017 En ligne : https://doi.org/10.1093/forestry/cpx032 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93217
in Forestry, an international journal of forest research > vol 91 n° 1 (January 2018) . - pp 49 - 62[article]Testing deformation hypotheses by constraints on a time series of geodetic observations / Hiddo Velsink in Journal of applied geodesy, vol 12 n° 1 (January 2018)
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Titre : Testing deformation hypotheses by constraints on a time series of geodetic observations Type de document : Article/Communication Auteurs : Hiddo Velsink, Auteur Année de publication : 2018 Article en page(s) : pp 77 - 94 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux
[Termes IGN] compensation par moindres carrés
[Termes IGN] congruence
[Termes IGN] déformation géométrique
[Termes IGN] programmation par contraintes
[Termes IGN] série temporelleRésumé : (auteur) In geodetic deformation analysis observations are used to identify form and size changes of a geodetic network, representing objects on the earth’s surface. The network points are monitored, often continuously, because of suspected deformations. A deformation may affect many points during many epochs. The problem is that the best description of the deformation is, in general, unknown. To find it, different hypothesised deformation models have to be tested systematically for agreement with the observations. The tests have to be capable of stating with a certain probability the size of detectable deformations, and to be datum invariant. A statistical criterion is needed to find the best deformation model. Existing methods do not fulfil these requirements. Here we propose a method that formulates the different hypotheses as sets of constraints on the parameters of a least-squares adjustment model. The constraints can relate to subsets of epochs and to subsets of points, thus combining time series analysis and congruence model analysis. The constraints are formulated as nonstochastic observations in an adjustment model of observation equations. This gives an easy way to test the constraints and to get a quality description. The proposed method aims at providing a good discriminating method to find the best description of a deformation. The method is expected to improve the quality of geodetic deformation analysis. We demonstrate the method with an elaborate example. Numéro de notice : A2018-016 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2017-0028 En ligne : https://doi.org/10.1515/jag-2017-0028 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89095
in Journal of applied geodesy > vol 12 n° 1 (January 2018) . - pp 77 - 94[article]A wavelet decomposition and polynomial fitting-based method for the estimation of time-varying residual motion error in airborne interferometric SAR / Hai Qiang Fu in IEEE Transactions on geoscience and remote sensing, vol 56 n° 1 (January 2018)
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Titre : A wavelet decomposition and polynomial fitting-based method for the estimation of time-varying residual motion error in airborne interferometric SAR Type de document : Article/Communication Auteurs : Hai Qiang Fu, Auteur ; Jian Jun Zhu, Auteur ; Chang Cheng Wang, Auteur ; Hui Qiang Wang, Auteur ; Rong Zhao, Auteur Année de publication : 2018 Article en page(s) : pp 49 - 59 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] estimation statistique
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] polarisation
[Termes IGN] résidu
[Termes IGN] transformation en ondelettesRésumé : (Auteur) Compensating the residual motion error (RME) is very important in airborne interferometric synthetic aperture radar (InSAR). In this paper, the wavelet decomposition and polynomial fitting-based (WDPF) method is proposed for detecting and correcting the RME. Wavelet decomposition with root-mean-square error (RMSE) change ratio-based decomposition scale identification is used to detect the RME from the differential interferogram. Polynomial fitting in combination with robust estimation-based least squares is used to absorb the incidence-angle-dependent and topography-dependent components of the RME. A simulated experiment was conducted to test the proposed WDPF method. High-precision RME (with an RMSE of 0.0375 rad) was obtained, which can meet the requirements of InSAR. Real-data L- and P-band InSAR experiments were also performed to test the WDPF method. The results confirmed that the WDPF method can effectively correct the RME for the interferogram. The RMSE of the estimated digital elevation model (DEM) was reduced from 8.03 to 3.46 m and 8.18 to 3.10 m for the L- and P-band interferograms, respectively. Finally, the effects of the external DEM error and polarization on the RME calibration were investigated. The results indicated that the global InSAR DEM products can fulfill the requirement of differential interferogram generation for the WDPF method, and the multipolarization interferograms can help to reduce the effect of the topographic error phase on RME estimation. Numéro de notice : A2018-184 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2017.2727076 Date de publication en ligne : 09/11/2017 En ligne : https://doi.org/10.1109/TGRS.2017.2727076 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89841
in IEEE Transactions on geoscience and remote sensing > vol 56 n° 1 (January 2018) . - pp 49 - 59[article]Benefits of satellite clock modeling in BDS and Galileo orbit determination / Yun Qing in Advances in space research, vol 60 n° 12 (15 December 2017)
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Titre : Benefits of satellite clock modeling in BDS and Galileo orbit determination Type de document : Article/Communication Auteurs : Yun Qing, Auteur ; Yidong Lou, Auteur ; Xiaolei Dai, Auteur ; Yang Liu, Auteur Année de publication : 2017 Article en page(s) : pp 2550 - 2560 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Techniques orbitales
[Termes IGN] constellation BeiDou
[Termes IGN] constellation Galileo
[Termes IGN] horloge atomique
[Termes IGN] modèle numérique
[Termes IGN] orbitographie
[Termes IGN] résiduRésumé : (auteur) In the process of Global Navigation Satellite Systems (GNSS) satellite orbit determination, satellite clocks are typically estimated as epoch-wise white noise in addition to the satellite orbit parameters. This results in high correlation between the satellite clock estimates and the satellite orbits, especially the radial component. In this paper, an appropriate clock model is proposed to constrain the satellite clock estimates in order to improve the accuracy of satellite orbits. SLR residuals and Day Boundary Discontinuities (DBDs) were used to assess the orbit quality. The benefits of satellite clock modeling in BDS and Galileo orbit determination is validated by experimental data sets. The results show that for satellites equipped with highly stable clocks, employing an appropriate linear model constraint for the clock estimates in orbit determination can result in an improved orbit consistency as well as accuracy. In detail, for Medium Earth Orbit (MEO) satellites, C12, C14, E11, E12 and E19, the improvements of DBDs range from 10% to 20%. Furthermore, the Standard Deviation (STD) of Satellite Laser Ranging (SLR) residuals were improved up to 30% for the Galileo satellites (using a passive hydrogen maser clock). Numéro de notice : A2017-753 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.asr.2017.03.040 Date de publication en ligne : 04/04/2017 En ligne : https://doi.org/10.1016/j.asr.2017.03.040 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89038
in Advances in space research > vol 60 n° 12 (15 December 2017) . - pp 2550 - 2560[article]Performance analysis of BDS/GPS precise point positioning with undifferenced ambiguity resolution / Min Wang in Advances in space research, vol 60 n° 12 (15 December 2017)
PermalinkAlgebraic method to speed up robust algorithms: example of laser-scanned point clouds / B. Palancz in Survey review, vol 49 n° 357 (December 2017)
PermalinkLarge-scale block adjustment without use of ground control points based on the compensation of geometric calibration for ZY-3 images / Yang Bo in ISPRS Journal of photogrammetry and remote sensing, vol 134 (December 2017)
PermalinkPer-pixel bias-variance decomposition of continuous errors in data-driven geospatial modeling : A case study in environmental remote sensing / Jing Gao in ISPRS Journal of photogrammetry and remote sensing, vol 134 (December 2017)
PermalinkSystematic error mitigation in multi-GNSS positioning based on semiparametric estimation / Wenkun Yu in Journal of geodesy, vol 91 n° 12 (December 2017)
PermalinkTropospheric delay modelling for the EGNOS augmentation system / Kamil Kazmierski in Survey review, vol 49 n° 357 (December 2017)
PermalinkIGS polar motion measurement accuracy / Jim Ray in Geodesy and Geodynamics, vol 8 n° 6 (November 2017)
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PermalinkIonospheric and receiver DCB-constrained multi-GNSS single-frequency PPP integrated with MEMS inertial measurements / Zhouzheng Gao in Journal of geodesy, vol 91 n° 11 (November 2017)
PermalinkNonlinear bias compensation of ZiYuan-3 satellite imagery with cubic splines / Jinshan Cao in ISPRS Journal of photogrammetry and remote sensing, vol 133 (November 2017)
Permalink3D building model-assisted snapshot positioning algorithm / Rakesh Kumar in GPS solutions, vol 21 n° 4 (October 2017)
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