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Uncertainties and errors in algorithms for elevation gradients / Dong Shi in International journal of geographical information science IJGIS, vol 35 n° 2 (February 2021)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 35 n° 2 (February 2021) . - pp 296 - 320 Titre : Uncertainties and errors in algorithms for elevation gradients Type de document : Article/Communication Auteurs : Dong Shi, Auteur ; Qinke Yang, Auteur ; Qifeng Zhu, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 296 - 320 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes descripteurs IGN] analyse comparative [Termes descripteurs IGN] erreur [Termes descripteurs IGN] filtrage du bruit [Termes descripteurs IGN] fonction harmonique [Termes descripteurs IGN] gradient d'altitude [Termes descripteurs IGN] gradient de pente [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] modèle numérique de surface [Termes descripteurs IGN] modèle numérique de terrain Résumé : (auteur) Elevation gradients are primary components of slope and aspect. Significant concerns remain when computing gradients if noise (perturbing non-DEM data) is present. There is still a need to find ways to balance accuracy of the gradient and stability to noise for specific types of DEM. In this study, six algorithms are compared using four DEMs and analyzed for stability to base level DEM noise and added random noise. Theoretical stability and accuracy of the formulae are analyzed using harmonic (frequency or spatial scale) response. The results provide a basis to determine the most appropriate algorithm for different situations. They show that: (1) the set (Evans-Young (EY), Sharpnack (Sp), Sobel (Sb)) has a better stability to noise ratio than the set (Zevenbergen (Z), Florinsky (F), Horn (H)). EY has the smoothest surface and the highest stability to noise ratio. If stability is the primary measure in mid-frequencies, EY is a good choice. (2) Sb is good because of its accuracy in mid to high frequencies. Out to the highest frequencies, Sb is the best. (3) F has potential but should not be used with very high-frequency noise. (4) H and Z should not be used when there is substantial noise. Numéro de notice : A2021-039 Affiliation des auteurs : non IGN Thématique : IMAGERIE/INFORMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2020.1766047 date de publication en ligne : 14/05/2020 En ligne : https://doi.org/10.1080/13658816.2020.1766047 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96748 [article]

Self-consistent determination of the Earth’s GM, geocenter motion and figure axis orientation / Alexandre Couhert in Journal of geodesy, vol 94 n° 12 (December 2020)  

Public [article]  inJournal of geodesy > vol 94 n° 12 (December 2020) . - n° 113 Titre : Self-consistent determination of the Earth’s GM, geocenter motion and figure axis orientation Type de document : Article/Communication Auteurs : Alexandre Couhert, Auteur ; Christian Bizouard, Auteur ; F. Mercier, Auteur ; Kristel Chanard , Auteur ; Marianne Greff-Lefftz, Auteur ; Pierre Exertier, Auteur Année de publication : 2020 Projets : 1-Pas de projet / Article en page(s) : n° 113 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes descripteurs IGN] données Ajisai [Termes descripteurs IGN] données Jason [Termes descripteurs IGN] données Lageos [Termes descripteurs IGN] données Lares [Termes descripteurs IGN] données Starlette [Termes descripteurs IGN] données Stella [Termes descripteurs IGN] données TLS (télémétrie) [Termes descripteurs IGN] erreur de modèle [Termes descripteurs IGN] harmonique sphérique [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] mouvement du géocentre [Termes descripteurs IGN] surface de la mer Résumé : (auteur) The very low-degree Earth’s gravity coefficients, associated with the largest-scale mass redistribution in the Earth’s fluid envelope (atmosphere, oceans and continental hydrology), are the most poorly known. In particular, the first three degree geopotential terms are important, as they relate to intrinsic Earth’s mass references: gravitational coefficient (GM) of the Earth (degree 0), geocenter motion (degree 1), Earth’s figure axis orientation (degree 2). This paper presents a self-consistent determination of these three properties of the Earth. The main objective is to deal with the remaining sources of altimetry satellite orbit uncertainties affecting the fundamental record of sea surface height measurements. The analysis identifies the modeling errors, which should be mitigated when estimating the geocenter coordinates from Satellite Laser Ranging (SLR) observations. The long-term behavior of the degree-0 and -2 spherical harmonics is also observed over the 34-year period 1984–2017 from the long-time history of satellite laser tracking to geodetic spherical satellites. From the analysis of the evolution of these two coefficients, constraints regarding the Earth’s rheology and uncertainties in the value of GM could be inferred. Overall, the influence of the orbit characteristics, SLR station ranging/position biases and satellite signature effects, measurement modeling errors (tropospheric corrections, non-tidal deformations) are also discussed. Numéro de notice : A2020-330 Affiliation des auteurs : UMR IPGP-Géod+Ext (2020- ) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01450-z date de publication en ligne : 18/11/2020 En ligne : https://doi.org/10.1007/s00190-020-01450-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96858 [article]

Urban climate services: climate impact projections and their uncertainties at city scale / Bert Van Schaeybroeck in FMI's climate bulletin research letters, vol 2020 n° 1 (Spring 2020)    

Public [article]  inFMI's climate bulletin research letters > vol 2020 n° 1 (Spring 2020) . - pp 12 - 13 Titre : Urban climate services: climate impact projections and their uncertainties at city scale Type de document : Article/Communication Auteurs : Bert Van Schaeybroeck, Auteur ; Bénédicte Bucher , Auteur ; et al., Auteur Année de publication : 2020 Projets : URCLIM / Masson, Valéry Article en page(s) : pp 12 - 13 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique [Termes descripteurs IGN] changement climatique [Termes descripteurs IGN] impact sur l'environnement [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] ville Résumé : (auteur) In many cities across Europe, both urban authorities and private actors have made strong commitments to adapt to future climate changes. Although a lot of climate information is available at the global and regional scale, this is often not the case at the local urban scale. Moreover, such information should account for a wide range of uncertainty factors ranging from global to city-scale development scenarios to uncertainties due to model errors. In an effort to lay the methodological groundworks for reliable urban climate services, URCLIM explores a compound handling of these uncertainties for various European cities and applies it to the assessment of adaptation measures. Numéro de notice : A2020-366 Affiliation des auteurs : LaSTIG+Ext (2020- ) Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : 10.35614/ISSN-2341-6408-IK-2020-05-RL date de publication en ligne : 25/05/2020 En ligne : https://doi.org/10.35614/ISSN-2341-6408-IK-2020-05-RL Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95404 [article]

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Camera orientation, calibration and inverse perspective with uncertainties: a Bayesian method applied to area estimation from diverse photographs / Grégoire Guillet in ISPRS Journal of photogrammetry and remote sensing, vol 159 (January 2020)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 159 (January 2020) . - pp 237 - 255 Titre : Camera orientation, calibration and inverse perspective with uncertainties: a Bayesian method applied to area estimation from diverse photographs Type de document : Article/Communication Auteurs : Grégoire Guillet, Auteur ; Thomas Guillet, Auteur ; Ludovic Ravanel, Auteur Année de publication : 2020 Article en page(s) : pp 237 - 255 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes descripteurs IGN] ajustement de paramètres [Termes descripteurs IGN] appariement d'images [Termes descripteurs IGN] autocorrélation spatiale [Termes descripteurs IGN] distorsion d'image [Termes descripteurs IGN] estimation bayesienne [Termes descripteurs IGN] étalonnage de chambre métrique [Termes descripteurs IGN] figuration de la densité [Termes descripteurs IGN] fonction inverse [Termes descripteurs IGN] image 2D [Termes descripteurs IGN] image aérienne [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] longueur focale [Termes descripteurs IGN] méthode de Monte-Carlo par chaînes de Markov [Termes descripteurs IGN] modèle numérique de surface [Termes descripteurs IGN] orientation externe [Termes descripteurs IGN] photographie numérique [Termes descripteurs IGN] vue 3D [Termes descripteurs IGN] vue perspective Résumé : (Auteur) Large collections of images have become readily available through modern digital catalogs, from sources as diverse as historical photographs, aerial surveys, or user-contributed pictures. Exploiting the quantitative information present in such wide-ranging collections can greatly benefit studies that follow the evolution of landscape features over decades, such as measuring areas of glaciers to study their shrinking under climate change. However, many available images were taken with low-quality lenses and unknown camera parameters. Useful quantitative data may still be extracted, but it becomes important to both account for imperfect optics, and estimate the uncertainty of the derived quantities. In this paper, we present a method to address both these goals, and apply it to the estimation of the area of a landscape feature traced as a polygon on the image of interest. The technique is based on a Bayesian formulation of the camera calibration problem. First, the probability density function (PDF) of the unknown camera parameters is determined for the image, based on matches between 2D (image) and 3D (world) points together with any available prior information. In a second step, the posterior distribution of the feature area of interest is derived from the PDF of camera parameters. In this step, we also model systematic errors arising in the polygon tracing process, as well as uncertainties in the digital elevation model. The resulting area PDF therefore accounts for most sources of uncertainty. We present validation experiments, and show that the model produces accurate and consistent results. We also demonstrate that in some cases, accounting for optical lens distortions is crucial for accurate area determination with consumer-grade lenses. The technique can be applied to many other types of quantitative features to be extracted from photographs when careful error estimation is important. Numéro de notice : A2020-015 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2019.11.013 date de publication en ligne : 02/12/2019 En ligne : https://doi.org/10.1016/j.isprsjprs.2019.11.013 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94404 [article]

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Vertical land motion in the Southwest and Central Pacific from available GNSS solutions and implications for relative sea levels / Valérie Ballu in Geophysical journal international, vol 218 n° 3 (September 2019)  

Public [article]  inGeophysical journal international > vol 218 n° 3 (September 2019) . - pp 1537 - 1551 Titre : Vertical land motion in the Southwest and Central Pacific from available GNSS solutions and implications for relative sea levels Type de document : Article/Communication Auteurs : Valérie Ballu, Auteur ; Médéric Gravelle, Auteur ; Guy Wöppelmann, Auteur ; Olivier de Viron, Auteur ; Paul Rebischung , Auteur ; Mélanie Becker, Auteur ; Pierre Sakic-Kieffer, Auteur Année de publication : 2019 Projets : STORISK / Duvat, Virginie, TOSCA / Article en page(s) : pp 1537 - 1551 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] changement du niveau de la mer [Termes descripteurs IGN] déformation verticale de la croute terrestre [Termes descripteurs IGN] données GNSS [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] Pacifique ouest [Termes descripteurs IGN] Pacifique Sud [Termes descripteurs IGN] série temporelle Résumé : (auteur) Coastal populations are impacted by relative sea level variations, which consist both of absolute sea level variations and of vertical land motions. This paper focuses on the Southwest and Central Pacific region, a recognized vulnerable region to sea level rise and where a large range of vertical land motion dynamics is observed. We analyse vertical displacement rates obtained from Global Navigation Satellite Systems (GNSS) by different analysis centres. We study the role played by modelled parameters, such as step discontinuities (due to equipment changes, earthquakes, etc.), in the position time-series analysis. We propose a new modelling approach based on a joint inversion of GNSS position time-series from different analysis centres. The final uncertainty on the vertical land motion rates is estimated as a combination of the uncertainty due to the GNSS data processing itself and the uncertainty due to the stability of the reference frame in which the GNSS data are expressed. We find that the dominant trend in the Southwest and Central Pacific is a moderate subsidence, with an average rate of −1.1 mm yr–1, but significant variations are observed, with displacement rates varying from an uplift of 1.6 ± 0.3 mm yr–1 to a subsidence of −5.4 ± 0.3 mm yr–1. Taking into account the geodynamic context, we assess, for each station, the relevance of current estimates of linear vertical displacement rate and uncertainty for forecasting future coastal sea levels. Numéro de notice : A2019-634 Affiliation des auteurs : Géodésie+Ext (mi2018-2019) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggz247 date de publication en ligne : 27/05/2019 En ligne : https://doi.org/10.1093/gji/ggz247 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95452 [article]

Total Vertical Uncertainty (TVU) modeling for topo-bathymetric LIDAR systems / Firat Eren in Photogrammetric Engineering & Remote Sensing, PERS, vol 85 n° 8 (August 2019)  

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Geometric and statistical interpretation of correlation between fault tests in integrated GPS/INS systems / Ali Almagbile in Journal of applied geodesy, vol 13 n° 3 (July 2019)  

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Uncertainty assessment of optical distance measurements at micrometer level accuracy for long-range applications / Joffray Guillory in IEEE Transactions on Instrumentation and Measurement, vol 68 n° 6 (June 2019)  

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A fuzzy formal concept analysis-based approach to uncovering spatial hierarchies among vague places extracted from user-generated data / Xiaoyu Wu in International journal of geographical information science IJGIS, Vol 33 n° 5-6 (May - June 2019)  

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Uncertainty in the effects of the modifiable areal unit problem under different levels of spatial autocorrelation : a simulation study / Sang-Il Lee in International journal of geographical information science IJGIS, Vol 33 n° 5-6 (May - June 2019)  

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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)  

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Method for an automatic alignment of imagery and vector data applied to cadastral information in Poland / Juan J. Ruiz-Lendínez in Survey review, vol 51 n° 365 (March 2019)  

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Improving the reliability of landslide susceptibility mapping through spatial uncertainty analysis: a case study of Al Hoceima, Northern Morocco / Hassane Rahali in Geocarto international, vol 34 n° 1 ([01/01/2019])  

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Recalage conjoint de données de cartographie mobile et de modèles 3D de bâtiments / Miloud Mezian (2019)  

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Exploring uncertainties in terrain feature extraction across multi-scale, multi-feature, and multi-method approaches for variable terrain / Boleslo E. Romero in Cartography and Geographic Information Science, Vol 45 n° 5 (August 2018)  

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