7-Publications IGN 2017
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GRACE era variability in the Earth's oblateness: a comparison of estimates from six different sources / Thierry Meyrath in Geophysical journal international, vol 208 n° 2 (February 2017)
[article]
Titre : GRACE era variability in the Earth's oblateness: a comparison of estimates from six different sources Type de document : Article/Communication Auteurs : Thierry Meyrath, Auteur ; Paul Rebischung , Auteur ; Tonie M. van Dam, Auteur Année de publication : 2017 Projets : 1-Pas de projet / Article en page(s) : pp 1126 - 1138 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] données GRACE
[Termes IGN] données TLS (télémétrie)
[Termes IGN] gravimétrie spatiale
[Termes IGN] longueur du jour
[Termes IGN] potentiel de pesanteur terrestre
[Termes IGN] rotation de la Terre
[Termes IGN] série temporelleRésumé : (auteur) We study fluctuations in the degree-2 zonal spherical harmonic coefficient of the Earth's gravity potential, C20, over the period 2003–2015. This coefficient is related to the Earth's oblateness and studying its temporal variations, ΔC20, can be used to monitor large-scale mass movements between high and low latitude regions. We examine ΔC20 inferred from six different sources, including satellite laser ranging (SLR), GRACE and global geophysical fluids models. We further include estimates that we derive from measured variations in the length-of-day (LOD), from the inversion of global crustal displacements as measured by GPS, as well as from the combination of GRACE and the output of an ocean model as described by Sun et al. We apply a sequence of trend and seasonal moving average filters to the different time-series in order to decompose them into an interannual, a seasonal and an intraseasonal component. We then perform a comparison analysis for each component, and we further estimate the noise level contained in the different series using an extended version of the three-cornered-hat method. For the seasonal component, we generally obtain a very good agreement between the different sources, and except for the LOD-derived series, we find that over 90 per cent of the variance in the seasonal components can be explained by the sum of an annual and semiannual oscillation of constant amplitudes and phases, indicating that the seasonal pattern is stable over the considered time period. High consistency between the different estimates is also observed for the intraseasonal component, except for the solution from GRACE, which is known to be affected by a strong tide-like alias with a period of about 161 d. Estimated interannual components from the different sources are generally in agreement with each other, although estimates from GRACE and LOD present some discrepancies. Slight deviations are further observed for the estimate from the geophysical models, likely to be related to the omission of polar ice and groundwater changes in the model combination we use. On the other hand, these processes do not seem to play an important role at seasonal and shorter timescales, as the sum of modelled atmospheric, oceanic and hydrological effects effectively explains the observed C20 variations at those scales. We generally obtain very good results for the solution from SLR, and we confirm that this well-established technique accurately tracks changes in C20. Good agreement is further observed for the estimate from the GPS inversion, showing that this indirect method is successful in capturing fluctuations in C20 on scales ranging from intra- to interannual. Obtaining accurate estimates from LOD, however, remains a challenging task and more reliable models of atmospheric wind fields are needed in order to obtain high-quality ΔC20, in particular at the seasonal scale. The combination of GRACE data and the output of an ocean model appears to be a promising approach, particularly since corresponding ΔC20 is not affected by tide-like aliases, and generally gives better results than the solution from GRACE, which still seems to be of rather poor quality. Numéro de notice : A2017-863 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/gji/ggw441 Date de publication en ligne : 24/11/2016 En ligne : https://doi.org/10.1093/gji/ggw441 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89852
in Geophysical journal international > vol 208 n° 2 (February 2017) . - pp 1126 - 1138[article]Seasonal low-degree changes in terrestrial water mass load from global GNSS measurements / Thierry Meyrath in Journal of geodesy, vol 91 n° 11 (November 2017)
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Titre : Seasonal low-degree changes in terrestrial water mass load from global GNSS measurements Type de document : Article/Communication Auteurs : Thierry Meyrath, Auteur ; Tonie M. van Dam, Auteur ; Xavier Collilieux , Auteur ; Paul Rebischung , Auteur Année de publication : 2017 Projets : 1-Pas de projet / Article en page(s) : pp 1 - 22 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] coordonnées GNSS
[Termes IGN] géocentre
[Termes IGN] masse d'eau
[Termes IGN] mouvement du géocentre
[Termes IGN] surcharge océanique
[Termes IGN] variation saisonnièreRésumé : (auteur) Large-scale mass redistribution in the terrestrial water storage (TWS) leads to changes in the low-degree spherical harmonic coefficients of the Earth’s surface mass density field. Studying these low-degree fluctuations is an important task that contributes to our understanding of continental hydrology. In this study, we use global GNSS measurements of vertical and horizontal crustal displacements that we correct for atmospheric and oceanic effects, and use a set of modified basis functions similar to Clarke et al. (Geophys J Int 171:1–10, 2007) to perform an inversion of the corrected measurements in order to recover changes in the coefficients of degree-0 (hydrological mass change), degree-1 (centre of mass shift) and degree-2 (flattening of the Earth) caused by variations in the TWS over the period January 2003–January 2015. We infer from the GNSS-derived degree-0 estimate an annual variation in total continental water mass with an amplitude of (3.49±0.19)×103 Gt and a phase of 70∘±3∘ (implying a peak in early March), in excellent agreement with corresponding values derived from the Global Land Data Assimilation System (GLDAS) water storage model that amount to (3.39±0.10)×103 Gt and 71∘±2∘, respectively. The degree-1 coefficients we recover from GNSS predict annual geocentre motion (i.e. the offset change between the centre of common mass and the centre of figure) caused by changes in TWS with amplitudes of 0.69±0.07 mm for GX, 1.31±0.08 mm for GY and 2.60±0.13 mm for GZ. These values agree with GLDAS and estimates obtained from the combination of GRACE and the output of an ocean model using the approach of Swenson et al. (J Geophys Res 113(B8), 2008) at the level of about 0.5, 0.3 and 0.9 mm for GX, GY and GZ, respectively. Corresponding degree-1 coefficients from SLR, however, generally show higher variability and predict larger amplitudes for GX and GZ. The results we obtain for the degree-2 coefficients from GNSS are slightly mixed, and the level of agreement with the other sources heavily depends on the individual coefficient being investigated. The best agreement is observed for TC20 and TS22, which contain the most prominent annual signals among the degree-2 coefficients, with amplitudes amounting to (5.47±0.44)×10−3 and (4.52±0.31)×10−3 m of equivalent water height (EWH), respectively, as inferred from GNSS. Corresponding agreement with values from SLR and GRACE is at the level of or better than 0.4×10−3 and 0.9×10−3 m of EWH for TC20 and TS22, respectively, while for both coefficients, GLDAS predicts smaller amplitudes. Somewhat lower agreement is obtained for the order-1 coefficients, TC21 and TS21, while our GNSS inversion seems unable to reliably recover TC22. For all the coefficients we consider, the GNSS-derived estimates from the modified inversion approach are more consistent with the solutions from the other sources than corresponding estimates obtained from an unconstrained standard inversion. Numéro de notice : A2017-311 Affiliation des auteurs : LASTIG LAREG+Ext (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-017-1028-8 Date de publication en ligne : 25/04/2017 En ligne : http://doi.org/10.1007/s00190-017-1028-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85361
in Journal of geodesy > vol 91 n° 11 (November 2017) . - pp 1 - 22[article]Terrain model reconstruction from terrestrial LiDAR data using radial basis functions / Jules Morel in IEEE Computer graphics and applications, vol 37 n° 5 ([01/09/2017])
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Titre : Terrain model reconstruction from terrestrial LiDAR data using radial basis functions Type de document : Article/Communication Auteurs : Jules Morel, Auteur ; Alexandra Bac, Auteur ; Cédric Vega , Auteur ; Cédric Vega , Auteur Année de publication : 2017 Projets : 2-Pas d'info accessible - article non ouvert / Article en page(s) : pp 72 - 84 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] fonction de base radiale
[Termes IGN] modèle numérique de terrainRésumé : (auteur) The presence of vegetation and the terrain topography itself generate strong occlusions causing large gaps in terrestrial laser scanning (TLS) data at the ground level as well as a risk of integrating above-ground objects. This article introduces a surface-approximation algorithm dedicated to extracting digital terrain models (DTMs) from terrestrial TLS data acquired in forest areas. The proposed method is based on the combination of a quadtree subdivision of space guided by the local density and distribution of data together with a surface modeling via radial basis functions, which are used as partitions of unity for merging local quadratic approximating patches. Numéro de notice : A2017-881 Affiliation des auteurs : LIF+Ext (2012-2019) Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/MCG.2017.3621225 Date de publication en ligne : 20/09/2017 En ligne : https://doi.org/10.1109/MCG.2017.3621225 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91402
in IEEE Computer graphics and applications > vol 37 n° 5 [01/09/2017] . - pp 72 - 84[article]The scale of VGI in map production: A perspective on European national mapping agencies / Ana-Maria Olteanu-Raimond in Transactions in GIS, vol 21 n° 1 (February 2017)
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Titre : The scale of VGI in map production: A perspective on European national mapping agencies Type de document : Article/Communication Auteurs : Ana-Maria Olteanu-Raimond , Auteur ; Glen Hart, Auteur ; Giles M. Foody, Auteur ; Guillaume Touya , Auteur ; et al., Auteur Année de publication : 2017 Projets : 3-projet - voir note / Article en page(s) : pp 74 – 90 Note générale : bibliographie
This study was supported by the COST Action TD1202 Mapping and the Citizen Sensor funded by the European Union Seventh Framework Programme and the European Science Foundation.Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées
[Termes IGN] complètement
[Termes IGN] données localisées des bénévoles
[Termes IGN] mise à jour
[Termes IGN] organisme cartographique national
[Termes IGN] qualité des donnéesRésumé : (auteur) The perspective of European National Mapping Agencies (NMA) on the role of citizen sensing in map production was explored. The NMAs varied greatly in their engagement with the community generating volunteered geographic information (VGI) and in their future plans. From an assessment of NMA standard practices, it was evident that much VGI was acquired with a positional accuracy that, while less than that typically acquired by NMAs, actually exceeded the requirements of the nominal data capture scale used by most NMAs. Opportunities for VGI use in map revision and updating were evident, especially for agencies that use a continuous rather than cyclical updating policy. Some NMAs had also developed systems to engage with citizen sensors and examples are discussed. Only rarely was VGI used to collect data on features beyond the standard set used by the NMAs. The potential role of citizen sensing and so its current scale of use by NMAs is limited by a series of concerns, notably relating to issues of data quality, the nature and motivation of the contributors, legal issues, the sustainability of data source, and employment fears of NMA staff. Possible priorities for future research and development are identified to help ensure that the potential of VGI in mapping is realized. Numéro de notice : A2017-161 Affiliation des auteurs : LASTIG COGIT+Ext (2012-2019) Autre URL associée : vers HAL ouvert Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12189 Date de publication en ligne : 25/06/2016 En ligne : http://dx.doi.org/10.1111/tgis.12189 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84685
in Transactions in GIS > vol 21 n° 1 (February 2017) . - pp 74 – 90[article]Linking spatial named entities to the web of data for geographical analysis of historical texts / Pierre-Henri Paris in Journal of Map & Geography Libraries, vol 13 n° 1 ([01/05/2017])
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Titre : Linking spatial named entities to the web of data for geographical analysis of historical texts Type de document : Article/Communication Auteurs : Pierre-Henri Paris, Auteur ; Nathalie Abadie , Auteur ; Carmen Brando , Auteur ; Carmen Brando , Auteur Année de publication : 2017 Projets : 2-Pas d'info accessible - article non ouvert / Article en page(s) : pp 82 - 110 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web
[Termes IGN] base de connaissances
[Termes IGN] corpus
[Termes IGN] entité géographique
[Termes IGN] exploration de texte
[Termes IGN] reconnaissance de noms
[Termes IGN] web des donnéesRésumé : (auteur) In our work, we are interested in facilitating the exploration by scholars of the geography of texts: in particular, historical narrative texts describing routes. Semantic annotation constitutes the first step to enrich such text with the necessary information for producing analytical maps. The present article focuses on the disambiguation of spatial named entities (SNE) by the attribution of an identifier of the ever-growing Web of Data. This giant knowledge base (KB) provides qualitative spatial information about geographic entities, in particular spatial relations such as (:Paris :southOf :Lille), (:Paris :country :France). We thus propose a graph-matching algorithm relying on the A* algorithm and graph-edit distances for choosing the best referent in the KB for the SNE. We performed preliminary experiments and noted the clear gain in performance. We propose some examples of maps that are built semi-automatically. Finally, we draw conclusions and describe our plans of future work. Numéro de notice : A2017-865 Affiliation des auteurs : LASTIG COGIT+Ext (2012-2019) Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/15420353.2017.1307306 Date de publication en ligne : 11/05/2017 En ligne : https://doi.org/10.1080/15420353.2017.1307306 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89872
in Journal of Map & Geography Libraries > vol 13 n° 1 [01/05/2017] . - pp 82 - 110[article]Effect of training class label noise on classification performances for land cover mapping with satellite image time series / Charlotte Pelletier in Remote sensing, vol 9 n° 2 (February 2017)PermalinkInvestigating the potential of deep neural networks for large-scale classification of very high resolution satellite images / Tristan Postadjian in ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, vol IV-1/W1 (May 2017)PermalinkIGS polar motion measurement accuracy / Jim Ray in Geodesy and Geodynamics, vol 8 n° 6 (November 2017)PermalinkStand-level wind damage can be assessed using diachronic photogrammetric canopy height models / Jean-Pierre Renaud in Annals of Forest Science, vol 74 n° 4 (December 2017)PermalinkMicMac – a free, open-source solution for photogrammetry / Ewelina Rupnik in Open Geospatial Data, Software and Standards, vol 2 (2017)PermalinkTerrestrial laser scanning as a tool for assessing tree growth / Jonathan Sheppard in iForest, biogeosciences and forestry, vol 10 n° 1 (February 2017)PermalinkFrequency of extreme Sahelian storms tripled since 1982 in satellite observations / Christopher M. Taylor in Nature letters, vol 544 n° 7651 (27 April 2017)PermalinkMICROSCOPE mission: First results of a space test of the equivalence principle / Pierre Touboul in Physical Review Letters, vol 119 n° 3 (December 2017)PermalinkAssessing crowdsourced POI quality: combining methods based on reference data, history, and spatial relations / Guillaume Touya in ISPRS International journal of geo-information, vol 6 n° 3 (March 2017)PermalinkExperiments to distribute and parallelize map generalization processes / Guillaume Touya in Cartographic journal (the), Vol 54 n° 4 (November 2017)Permalink