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Interrogations au sommet / Michel Ravelet in Géomètre, n° 2129 (octobre 2015)

Public [article]  inGéomètre > n° 2129 (octobre 2015) . - pp 6 - 9 Titre : Interrogations au sommet Type de document : Article/Communication Auteurs : Michel Ravelet, Auteur Année de publication : 2015 Article en page(s) : pp 6 - 9 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] altitude [Termes IGN] Mont-Blanc, massif du [Termes IGN] sommet (relief) Résumé : (auteur) Les résultats de la dernière campagne de mesures du Mont Blanc surprend la communauté scientifique. Retour sur cet évènement. Numéro de notice : A2015-647 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78153 [article]

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Filtering Global land and surface altimetry data (GLA14) for elevation accuracy determination / Jean-Samuel Proulx-Bourque in Photogrammetric Engineering & Remote Sensing, PERS, vol 81 n° 9 (September 2015)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 81 n° 9 (September 2015) . - pp 701 - 707 Titre : Filtering Global land and surface altimetry data (GLA14) for elevation accuracy determination Type de document : Article/Communication Auteurs : Jean-Samuel Proulx-Bourque, Auteur ; Ramata Magagi, Auteur ; Norman T. O’Neill, Auteur Année de publication : 2015 Article en page(s) : pp 701 - 707 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] altimétrie satellitaire par radar [Termes IGN] altitude [Termes IGN] Canada [Termes IGN] données altimétriques [Termes IGN] données ICEsat [Termes IGN] filtrage numérique d'image Résumé : (auteur) This paper presents a filtering method for ICESat Global Land Surface Altimetry data (GLA14), which is based on indicators to detect potentially contaminated GLA14 elevation points. Potential contamination sources include attitude miscalculation, saturated echoes, equipment noise, the atmosphere, and variable elevation within footprints. For a study site located in Northern Canada, this multi-indicator filter provided a 19 percent reduction in the root mean square error for elevation, when compared to Canadian Digital Elevation Data (CDED). This result demonstrates the method’s ability to provide an improved dataset for vertical accuracy evaluation, with respect to unfiltered GLA14 data. The improvement was achieved with a rejection rate of 69 percent. However, due to the high density of the unfiltered GLA14 data over the study site, a spatially homogeneous distribution of elevation points was maintained, even after filtering. Results also showed the rejection efficiency of most indicators, as well as their complementarity. Numéro de notice : A2015-984 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.81.9.701 En ligne : https://doi.org/10.14358/PERS.81.9.701 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80265 [article]

Genetic differentiation of European larch along an altitudinal gradient in the French Alps / Maxime Nardin in Annals of Forest Science, vol 72 n° 5 (July 2015)  

Public [article]  inAnnals of Forest Science > vol 72 n° 5 (July 2015) . - pp 517-527 Titre : Genetic differentiation of European larch along an altitudinal gradient in the French Alps Type de document : Article/Communication Auteurs : Maxime Nardin, Auteur ; Brigitte Musch, Auteur ; Yves Rousselle, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 517-527 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] Alpes (France) [Termes IGN] altitude [Termes IGN] cambium [Termes IGN] classification de Dempster-Shafer [Termes IGN] diversité génétique [Termes IGN] génétique [Termes IGN] gradient [Termes IGN] Larix decidua [Termes IGN] montagne [Termes IGN] placette d'échantillonnage [Termes IGN] variabilité génétique Résumé : (Auteur) Key message : Despite variable dynamics of genetic diversification at the different altitudinal levels, strong gene flow tends to standardize larch genetic diversity: the larch forest distributed along the altitudinal gradient can be regarded as a single population. Context : While in forest tree species many studies focus on the structure of the genetic diversity at the natural range and at the forest stand levels, few studies have worked at intermediate levels like the landscape level. Aims : We tried to determine to what degree altitude variation can affect the genetic diversity and the local structure of the genetic diversity of European larch (Larix decidua Miller) at the landscape level. Methods : Using microsatellite markers, we determined the between- and within-plot genetic structure and the spatial genetic structure (SGS) of four altitudinal plots distributed between 1,350 and 2,300 m a.s.l. in a European larch forest located in the French Alps. Results : A homogenous neutral genetic structure was detected along this gradient. The intensity of the SGS was found to be stronger at 2,300 m and decreased at the 2,000-m plot. It was low or non-existent at the 1,700- and 1,350-m altitudinal levels. Conclusion : Our results suggest that the genetic structure observed at the landscape level in this European larch forest was only slightly affected by climatic variation, human activities, or historical events. However, the variation of intensity of the SGS within the altitudinal plots indicates the existence of variable genetic dynamics, despite the globally uniform genetic structure along the altitudinal gradient. Numéro de notice : A2015-413 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-015-0483-8 Date de publication en ligne : 30/04/2015 En ligne : https://doi.org/10.1007/s13595-015-0483-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76903 [article]

Accuracy of unmodified Stokes’ integration in the R-C-R procedure for geoid computation / Zahra Ismaïl in Journal of applied geodesy, vol 9 n° 2 (June 2015)  

Public [article]  inJournal of applied geodesy > vol 9 n° 2 (June 2015) . - pp 112 - 122 Titre : Accuracy of unmodified Stokes’ integration in the R-C-R procedure for geoid computation Type de document : Article/Communication Auteurs : Zahra Ismaïl, Auteur ; Olivier Jamet , Auteur Année de publication : 2015 Projets : 3-projet - voir note / Article en page(s) : pp 112 - 122 Note générale : bibliographie This work was supported by a doctoral scholarship from the University of Tichrine, Latakia, Syria. Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altitude [Termes IGN] anomalie de pesanteur [Termes IGN] Earth Gravity Model 2008 [Termes IGN] géoïde [Termes IGN] GravSoft [Termes IGN] harmonique sphérique [Termes IGN] intégrale de Stokes [Termes IGN] montagne Résumé : (auteur) Geoid determinations by the Remove-Compute-­Restore (R-C-R) technique involves the application of Stokes’ integral on reduced gravity anomalies. Numerical Stokes’ integration produces an error depending on the choice of the integration radius, grid resolution and Stokes’ kernel function. In this work, we aim to evaluate the accuracy of Stokes’ integral through a study on synthetic gravitational signals derived from EGM2008 on three different landscape areas with respect to the size of the integration domain and the resolution of the anomaly grid. The influence of the integration radius was studied earlier by several authors. Using real data, they found that the choice of relatively small radii (less than 1°) enables to reach an optimal accuracy. We observe a general behaviour coherent with these earlier studies. On the other hand, we notice that increasing the integration radius up to 2° or 2.5° might bring significantly better results. We note that, unlike the smallest radius corresponding to a local minimum of the error curve, the optimal radius in the range 0° to 6° depends on the terrain characteristics. We also find that the high frequencies, from degree 600, improve continuously with the integration radius in both semi-­mountainous and mountain areas. Finally, we note that the relative error of the computed geoid heights depends weakly on the anomaly spherical harmonic degree in the range from degree 200 to 2000. It remains greater than 10 % for any integration radii up to 6°. This result tends to prove that a one centimetre accuracy cannot be reached in semi-mountainous and mountainous regions with the unmodified Stokes’ kernel. Numéro de notice : A2015-391 Affiliation des auteurs : LASTIG LAREG (2012-mi2018) Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2014-0026 En ligne : http://dx.oi.org/10.1515/jag-2014-0026 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76860 [article]

Development of new hybrid geoid model for Japan, "GSIGEO2011" / Basara Miyahara in Bulletin of the GeoSpatial Information authority of Japan, vol 62 (December 2014)  

Public [article]  inBulletin of the GeoSpatial Information authority of Japan > vol 62 (December 2014) . - pp 11 - 20 Titre : Development of new hybrid geoid model for Japan, "GSIGEO2011" Type de document : Article/Communication Auteurs : Basara Miyahara, Auteur ; Tokuro Kodama, Auteur ; Yuki Kuroishi, Auteur Année de publication : 2014 Article en page(s) : pp 11 - 20 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] altitude orthométrique [Termes IGN] collocation par moindres carrés [Termes IGN] géoïde gravimétrique [Termes IGN] géoïde local [Termes IGN] nivellement [Termes IGN] positionnement par GNSS Résumé : (auteur) We have developed a new hybrid geoid model of Japan, “GSIGEO2011”, which was made publicly available on April 1, 2014. The model was created in such a way that a high-resolution gravimetric geoid model for Japan, “JGEOID2008” was fitted to GNSS/leveling geoid undulations at 971 sites by the Least-Squares Collocation method. The model reproduces geoid heights at the GNSS/leveling sites with the consistency of a standard deviation of 1.8 cm. By utilizing the model to convert GNSS-derived three-dimensional positions to orthometric heights, GNSS survey can determine orthometric heights at the same precision as third-order leveling surveys. Orthometric height determination by GNSS surveying has been applicable in public surveys as alternative to third-order leveling in Japan since April 1 2014. Numéro de notice : A2014-706 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans En ligne : https://www.gsi.go.jp/common/000099005.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75516 [article]

Le champ de pesanteur en quelques mots / Françoise Duquenne in XYZ, n° 139 (juin - août 2014) 

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Essai sur la découverte du g et son incidence en topographie / Paul Courbon in XYZ, n° 139 (juin - août 2014) 

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Mont Blanc : peu de changement / Anonyme in Géomètre, n° 2107 (octobre 2013)

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CIRCE RHONE : mise en place d'une grille de transformation altimétrique entre les altitudes orthométriques (NGF/Lallemand) et normales (NGF/IGN69) / Paul-Henri Faure in XYZ, n° 134 (mars - mai 2013) 

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Global height system unification with GOCE: a simulation study on the indirect bias term in the GBVP approach / C. Gerlach in Journal of geodesy, vol 87 n° 1 (January 2013)  

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Selected papers, Tome 2. Version 5.d / Abdelmajid Ben Hadj Salem (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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Analyse en relativité d’échelle du bassin versant du Gardon (Gard, France) : Étude de la variation de la dimension fractale en fonction de l’altitude et de l’échelle / L. Nottale in Revue internationale de géomatique, vol 22 n° 1 (mars - mai 2012)  

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Auvergne dataset: Testing several geoid computation methods / Pierre Valty (2012)  

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Singular spectrum analysis of global mean sea level variations / S. Khelifa in Bulletin des sciences géographiques, n° 26 (octobre 2011)

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Le toit de l'Europe sous surveillance / Anonyme in Géomètre, n° 2085 (octobre 2011)

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Utilisation de la technique du nivellement par GPS pour l'élaboration des surfaces de conversions altimétriques / S. Medjahed in Bulletin des sciences géographiques, n° 26 (octobre 2011)

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Simulation study of the influence of the ionospheric layer height in the thin layer ionospheric model / C. Brunini in Journal of geodesy, vol 85 n° 9 (September 2011)  

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On improving precision of GPS-derived height times series at GEONET stations / H. Munekane in Bulletin of the GeoSpatial Information authority of Japan, vol 58 (December 2010)  

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The combination of GNSS-levelling data and gravimetric (quasi-) geoid heights in the presence of noise / R. Klees in Journal of geodesy, vol 84 n° 12 (December 2010)  

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The effect of EGM2008-based normal, normal-orthometric and Helmert orthometric height systems on the Australian levelling network / M. Filmer in Journal of geodesy, vol 84 n° 8 (August 2010)  

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Integer least-squares theory for the GNSS compass / Peter J.G. Teunissen in Journal of geodesy, vol 84 n° 7 (July 2010)  

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Assessing the accuracy of GEOID03 and GEOID09 in Connecticut / Thomas H. Meyer in SaLIS Surveying and land information science, vol 70 n° 2 (Summer 2010)

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Establishment of an empirical Geoid Model for a small geographic area: a case study of Port Harcourt, Nigeria / J. Olaleye in SaLIS Surveying and land information science, vol 70 n° 1 (Spring 2010)

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Relation between the Italian and European height systems / Alessandro Caporali in Bulletin of geodesy and geomatics BGG, vol 69 n° 1 (March 2010)

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