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Precise local quasigeoid modelling using GNSS/levelling height anomalies and gravity data / Marek Trojanowicz in Survey review, Vol 52 n°370 (January 2020)  

Public [article]  inSurvey review > Vol 52 n°370 (January 2020) . - pp 76 - 83 Titre : Precise local quasigeoid modelling using GNSS/levelling height anomalies and gravity data Type de document : Article/Communication Auteurs : Marek Trojanowicz, Auteur ; Edward Osada, Auteur ; Krzysztof Karsznia, Auteur Année de publication : 2020 Article en page(s) : pp 76 - 83 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] collocation par moindres carrés [Termes IGN] données géophysiques [Termes IGN] données GNSS [Termes IGN] Earth Gravity Model 2008 [Termes IGN] erreur en altitude [Termes IGN] fonction spline d'interpolation [Termes IGN] formule de Molodensky [Termes IGN] modèle de géopotentiel local [Termes IGN] modèle numérique de surface [Termes IGN] nivellement [Termes IGN] Pologne [Termes IGN] quasi-géoïde Résumé : (auteur) This study compares four approaches of local quasigeoid modelling using GNSS/levelling height anomalies. The first two approaches utilise only a dense network of points with known GNSS/levelling height anomalies and the EGM2008 model. They are based on the interpolation of residual values of height anomalies by applying the least squares collocation (LSC) and the thin plate spline (TPS). The next two approaches use additional data in the form of surface gravity data and the digital elevation model. One of these approaches is based on the classical Molodensky method combined with LSC. The other approach utilises the method of geophysical gravity data inversion (GGI). During the research, the authors used a local network of points with precisely defined GNSS/levelling height anomalies located in South-Western Poland. They obtained comparable results for all tested approaches at the maximum analysed density of GNSS/levelling points (about 1point30km2). The differences between the modelling results became apparent only with an increase in the distance between the GNSS/levelling data points and the reduced accuracy of the used global geopotential model. Numéro de notice : A2020-027 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2018.1525981 Date de publication en ligne : 10/10/2018 En ligne : https://doi.org/10.1080/00396265.2018.1525981 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94479 [article]

Consistency and analysis of ionospheric observables obtained from three precise point positioning models / Yan Xiang in Journal of geodesy, vol 93 n° 8 (August 2019)  

Public [article]  inJournal of geodesy > vol 93 n° 8 (August 2019) . - pp 1161–1170 Titre : Consistency and analysis of ionospheric observables obtained from three precise point positioning models Type de document : Article/Communication Auteurs : Yan Xiang, Auteur ; Yang Gao, Auteur ; Junbo Shi, Auteur ; Chaoqian Xu, Auteur Année de publication : 2019 Article en page(s) : pp 1161–1170 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] cohérence géométrique [Termes IGN] erreur de positionnement [Termes IGN] erreur en altitude [Termes IGN] erreur systématique [Termes IGN] mesurage de phase [Termes IGN] modèle ionosphérique [Termes IGN] positionnement différentiel [Termes IGN] positionnement ponctuel précis [Termes IGN] propagation ionosphérique Résumé : (auteur) Ionospheric observables based on Global Navigation Satellite System can be obtained by a variety of approaches. The most widely used one is the geometry-free combination of carrier-phase smoothed code measurements. This method, however, introduces leveling errors that substantially degrade the performance of ionospheric modeling and bias estimation. To reduce leveling errors, precise point positioning (PPP) model is preferred for obtaining the ionospheric observables. We aim to investigate whether the ionospheric observables obtained from three different PPP models are consistent and how the PPP-based ionospheric observables relates to the smoothed code method. The paper begins by formulating the ionospheric observables. We then explain the statistical evaluation methods used for analyzing the bias terms derived from these methods and assessing the leveling errors from the carrier-phase smoothed code method. Numerical analysis is then conducted to compare the bias terms in the ionospheric observables and evaluate the leveling errors. The ionospheric observables based on the three PPP models show strong consistency. Compared to leveling errors in the carrier-phase smoothed code method, the leveling errors using the uncombined PPP model are significantly reduced up to five times. Numéro de notice : A2019-384 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-019-01233-1 Date de publication en ligne : 12/02/2019 En ligne : https://doi.org/10.1007/s00190-019-01233-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93463 [article]

The influence of artificial illumination of invar levelling rods / Štefan Rákay in Geodetski vestnik, vol 62 n° 4 (December 2018 - February 2019)  

Public [article]  inGeodetski vestnik > vol 62 n° 4 (December 2018 - February 2019) . - pp 619 - 629 Titre : The influence of artificial illumination of invar levelling rods Type de document : Article/Communication Auteurs : Štefan Rákay, Auteur ; Slavomír Labant, Auteur ; Karol Bartoš, Auteur ; Katarína Pukanská, Auteur Année de publication : 2018 Article en page(s) : pp 619 - 629 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Nivellement [Termes IGN] angle d'incidence [Termes IGN] détecteur à transfert de charge [Termes IGN] détection d'erreur [Termes IGN] éclairement lumineux [Termes IGN] erreur en altitude [Termes IGN] erreur systématique [Termes IGN] mire de nivellement [Termes IGN] niveau numérique [Termes IGN] stadia Invar Résumé : (auteur) Since the digital levels operate on the principle of image processing of the bar code of levelling rod, recorded by a CCD sensor, the proper lighting (i.e. illumination of the bar code) is important to achieve accurate results. The prevention of inappropriate lighting conditions is important for the correct recording of the image of bar code section. This paper examines the systematic error as a function of the angle of incidence at which an bar code is illuminated by artificial lighting in low light conditions. Further, the procedure of measurements and the analysis of results for the identification of such errors is proposed. The results of experimental measurements highlight the inappropriateness of bar code illumination at an angle of incidence of more than about 45 °. From the practical measurements, it was found that the angle of incidence 55 ° corresponds to an error of about 0.02 mm, which is twice as much as the resolution of the height measurement determined by the manufacturer. Numéro de notice : A2019-015 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.15292/geodetski-vestnik.2018.04.619-629 Date de publication en ligne : 30/11/2018 En ligne : https://doi.org/10.15292/geodetski-vestnik.2018.04.619-629 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91624 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
139-2018041	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Accuracy assessment of the global TanDEM-X Digital Elevation Model with GPS data / Birgit Wessel in ISPRS Journal of photogrammetry and remote sensing, vol 139 (May 2018)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 139 (May 2018) . - pp 171 - 182 Titre : Accuracy assessment of the global TanDEM-X Digital Elevation Model with GPS data Type de document : Article/Communication Auteurs : Birgit Wessel, Auteur ; Martin Huber, Auteur ; Christian Wohlfart, Auteur ; Ursula Marschalk, Auteur ; Detlev Kosmann, Auteur ; Achim Roth, Auteur Année de publication : 2018 Article en page(s) : pp 171 - 182 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] erreur en altitude [Termes IGN] évaluation des données [Termes IGN] MNS TerraSAR & TanDEM-X [Termes IGN] modèle numérique de surface [Termes IGN] précision de localisation Résumé : (Auteur) The primary goal of the German TanDEM-X mission is the generation of a highly accurate and global Digital Elevation Model (DEM) with global accuracies of at least 10 m absolute height error (linear 90% error). The global TanDEM-X DEM acquired with single-pass SAR interferometry was finished in September 2016. This paper provides a unique accuracy assessment of the final TanDEM-X global DEM using two different GPS point reference data sets, which are distributed across all continents, to fully characterize the absolute height error. Firstly, the absolute vertical accuracy is examined by about three million globally distributed kinematic GPS (KGPS) points derived from 19 KGPS tracks covering a total length of about 66,000 km. Secondly, a comparison is performed with more than 23,000 “GPS on Bench Marks” (GPS-on-BM) points provided by the US National Geodetic Survey (NGS) scattered across 14 different land cover types of the US National Land Cover Data base (NLCD). Both GPS comparisons prove an absolute vertical mean error of TanDEM-X DEM smaller than ±0.20 m, a Root Means Square Error (RMSE) smaller than 1.4 m and an excellent absolute 90% linear height error below 2 m. The RMSE values are sensitive to land cover types. For low vegetation the RMSE is ±1.1 m, whereas it is slightly higher for developed areas (±1.4 m) and for forests (±1.8 m). This validation confirms an outstanding absolute height error at 90% confidence level of the global TanDEM-X DEM outperforming the requirement by a factor of five. Due to its extensive and globally distributed reference data sets, this study is of considerable interests for scientific and commercial applications. Numéro de notice : A2018-611 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2018.02.017 En ligne : https://doi.org/10.1016/j.isprsjprs.2018.02.017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89551 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-2018051	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Exploring the sensitivity of coastal inundation modelling to DEM vertical error / Harry West in International journal of geographical information science IJGIS, vol 32 n° 5-6 (May - June 2018)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 32 n° 5-6 (May - June 2018) . - pp 1172 - 1193 Titre : Exploring the sensitivity of coastal inundation modelling to DEM vertical error Type de document : Article/Communication Auteurs : Harry West, Auteur ; Michael Horswell, Auteur ; Nevil Quinn, Auteur Année de publication : 2018 Article en page(s) : pp 1172 - 1193 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] analyse de sensibilité [Termes IGN] erreur en altitude [Termes IGN] estuaire [Termes IGN] incertitude géométrique [Termes IGN] inondation [Termes IGN] littoral [Termes IGN] méthode de Monte-Carlo [Termes IGN] modèle numérique de surface [Termes IGN] montée du niveau de la mer [Termes IGN] Royaume-Uni Résumé : (Auteur) As sea level is projected to rise throughout the twenty-first century due to climate change, there is a need to ensure that sea level rise (SLR) models accurately and defensibly represent future flood inundation levels to allow for effective coastal zone management. Digital elevation models (DEMs) are integral to SLR modelling, but are subject to error, including in their vertical resolution. Error in DEMs leads to uncertainty in the output of SLR inundation models, which if not considered, may result in poor coastal management decisions. However, DEM error is not usually described in detail by DEM suppliers; commonly only the RMSE is reported. This research explores the impact of stated vertical error in delineating zones of inundation in two locations along the Devon, United Kingdom, coastline (Exe and Otter Estuaries). We explore the consequences of needing to make assumptions about the distribution of error in the absence of detailed error data using a 1 m, publically available composite DEM with a maximum RMSE of 0.15 m, typical of recent LiDAR-derived DEMs. We compare uncertainty using two methods (i) the NOAA inundation uncertainty mapping method which assumes a normal distribution of error and (ii) a hydrologically correct bathtub method where the DEM is uniformly perturbed between the upper and lower bounds of a 95% linear error in 500 Monte Carlo Simulations (HBM+MCS). The NOAA method produced a broader zone of uncertainty (an increase of 134.9% on the HBM+MCS method), which is particularly evident in the flatter topography of the upper estuaries. The HBM+MCS method generates a narrower band of uncertainty for these flatter areas, but very similar extents where shorelines are steeper. The differences in inundation extents produced by the methods relate to a number of underpinning assumptions, and particularly, how the stated RMSE is interpreted and used to represent error in a practical sense. Unlike the NOAA method, the HBM+MCS model is computationally intensive, depending on the areas under consideration and the number of iterations. We therefore used the HBM+ MCS method to derive a regression relationship between elevation and inundation probability for the Exe Estuary. We then apply this to the adjacent Otter Estuary and show that it can defensibly reproduce zones of inundation uncertainty, avoiding the computationally intensive step of the HBM+MCS. The equation-derived zone of uncertainty was 112.1% larger than the HBM+MCS method, compared to the NOAA method which produced an uncertain area 423.9% larger. Each approach has advantages and disadvantages and requires value judgements to be made. Their use underscores the need for transparency in assumptions and communications of outputs. We urge DEM publishers to move beyond provision of a generalised RMSE and provide more detailed estimates of spatial error and complete metadata, including locations of ground control points and associated land cover. Numéro de notice : A2018-203 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2018.1444165 Date de publication en ligne : 14/03/2018 En ligne : https://doi.org/10.1080/13658816.2018.1444165 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89874 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-2018031	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Improved topographic mapping through high-resolution SAR interferometry with atmospheric effect removal / Mingsheng Liao in ISPRS Journal of photogrammetry and remote sensing, vol 80 (June 2013)  

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The height datum problem and the role of satellite gravity models / A. Gatti in Journal of geodesy, vol 87 n° 1 (January 2013)  

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Qualification de modèles numériques de terrain Lidar pour l'étude de l'érosion : application aux badlands de Draix / F. Panissod in Revue Française de Photogrammétrie et de Télédétection, n° 192 (Septembre 2010)

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Vertical accuracy of digital elevation model from Shuttle Radar Topographic Mission: a case study / Ashu Sharma in Geocarto international, vol 25 n° 4 (July 2010)  

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Caractérisation d'erreurs sur un modèle numérique de terrain en fonction de zones morphologiques / Frédéric Rousseaux in Bulletin d'information scientifique et technique de l'IGN, n° 75 (mars 2006) 

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