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Tropospheric refractivity and zenith path delays from least-squares collocation of meteorological and GNSS data / Karina Wilgan in Journal of geodesy, vol 91 n° 2 (February 2017)
[article]
Titre : Tropospheric refractivity and zenith path delays from least-squares collocation of meteorological and GNSS data Type de document : Article/Communication Auteurs : Karina Wilgan, Auteur ; Fabian Peter Hurter, Auteur ; Alain Geiger, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 117 - 134 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] collocation par moindres carrés
[Termes IGN] données GNSS
[Termes IGN] données météorologiques
[Termes IGN] modèle atmosphérique
[Termes IGN] prévision météorologique
[Termes IGN] propagation troposphérique
[Termes IGN] réfringence
[Termes IGN] retard troposphérique zénithalRésumé : (Auteur) Precise positioning requires an accurate a priori troposphere model to enhance the solution quality. Several empirical models are available, but they may not properly characterize the state of troposphere, especially in severe weather conditions. Another possible solution is to use regional troposphere models based on real-time or near-real time measurements. In this study, we present the total refractivity and zenith total delay (ZTD) models based on a numerical weather prediction (NWP) model, Global Navigation Satellite System (GNSS) data and ground-based meteorological observations. We reconstruct the total refractivity profiles over the western part of Switzerland and the total refractivity profiles as well as ZTDs over Poland using the least-squares collocation software COMEDIE (Collocation of Meteorological Data for Interpretation and Estimation of Tropospheric Pathdelays) developed at ETH Zürich. In these two case studies, profiles of the total refractivity and ZTDs are calculated from different data sets. For Switzerland, the data set with the best agreement with the reference radiosonde (RS) measurements is the combination of ground-based meteorological observations and GNSS ZTDs. Introducing the horizontal gradients does not improve the vertical interpolation, and results in slightly larger biases and standard deviations. For Poland, the data set based on meteorological parameters from the NWP Weather Research and Forecasting (WRF) model and from a combination of the NWP model and GNSS ZTDs shows the best agreement with the reference RS data. In terms of ZTD, the combined NWP-GNSS observations and GNSS-only data set exhibit the best accuracy with an average bias (from all stations) of 3.7 mm and average standard deviations of 17.0 mm w.r.t. the reference GNSS stations. Numéro de notice : A2017-062 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0942-5 En ligne : http://dx.doi.org/10.1007/s00190-016-0942-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84275
in Journal of geodesy > vol 91 n° 2 (February 2017) . - pp 117 - 134[article]
Titre : Monitoring rock glaciers by combining photogrammetric and GNSS-based methods Type de document : Thèse/HDR Auteurs : Fabian Neyer, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2017 Autre Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 99 Importance : 174 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-45-1 Note générale : bibliographie
thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] Alpes centrales
[Termes IGN] champ de vitesse
[Termes IGN] collocation par moindres carrés
[Termes IGN] déformation de la croute terrestre
[Termes IGN] données localisées 3D
[Termes IGN] glacier
[Termes IGN] image terrestre
[Termes IGN] matrice de covariance
[Termes IGN] pergélisol
[Termes IGN] reconstruction 3D
[Termes IGN] rocher
[Termes IGN] série temporelle
[Termes IGN] SuisseIndex. décimale : 30.60 Géodésie spatiale Résumé : (auteur) Rock glaciers are creeping landforms of perennially frozen ground and belong to the permafrost creeping phenomena. They are mainly composed of rock debris that accumulate in areas of high natural erosion. Ice particles between the rocks cause the moving accumulation in steep terrain to dynamically flow downslope. In the Alpine region, these morphological landforms mainly occur at north-facing mountain slopes in high altitudes above the forest boundary and are known for their sensitivity to climate change.
For several decades, rock glaciers have been monitored for scientific aims, while advances in surveying technologies increased the interest in such studies since the 1990s. Modern technologies in remote sensing (e.g., airborne imagery or satellite-based measurement techniques) are often combined with measurements from field campaigns, i.e., measurements taken directly on a rock glacier (e.g., GNSS, laser-scanning, ground temperature measurements, etc). The high-level goal is to enhance the process understanding, especially with respect to the changing climate: various studies indicate an extended risk of slope failures in steep frozen bedrock due to the global temperature increase. Early recognition of increased activities help to inform local authorities in the endangered areas about the potential hazard before such an event.
The present work is part of the X-Sense project (Nano-Tera.ch), with an interdisciplinary team of scientists that build and operate new low-cost devices for data acquisition, develop new data processing pipelines and algorithms for evaluation, and also gain new insight of natural processes in these regions. Autonomous measurement systems, developed within other work packages in the X-Sense project, observe different permafrost creep areas with high resolution in space and time. Combined with multi-year observations, the derived surface motions are used to obtain an improved process understanding.
This work focuses on the photogrammetric image processing in order to retrieve precise surface displacement estimates. More precisely, image sequences, acquired with two permanently installed commercial digital single-reflex cameras, are used to measure topographic changes in the observed permafrost area. By the combination with high resolution GNSS positioning results, the goal is to obtain precise time series of moving rock boulders at different positions within the field of view. Challenges arising from the combination of different data sets, the development of an automatic processing pipeline, and an improvement of the processing strategy in general, are the main tasks of this thesis.
The study site is the bordering area above the Grabengufer rock glacier (Mattervalley VS, Switzerland), known as the Grabengufer rock slide. Local topographic conditions allowed only a partially good installation geometry for the photogrammetric reconstruction. With respect to a 3D reconstruction without the use of GNSS coordinates, an accuracy increase of about one order of magnitude could be achieved in case these high-precision solutions were integrated. More specifically, respective standard deviations for the East, North, and Height components of 6, 5, and 2 cm were achieved. The stated accuracy, maintained throughout the measurement period of nearly four years (summer months), was obtained in an area of approximately 80m×80 m, with a mean distance of 80 m from the two cameras.
Position time series of moving rock boulders were filtered using the principles of collocation. Analyzing the correlation characteristics of the stochastic signal, an optimal correlation length was computed and used to extract relevant signals from the noise contaminated time series. Velocity was directly estimated as a derived quantity in the collocation process. Furthermore, the techniques of the adaptive collocation approach is presented. This iterative method uses the principles of a dynamically adjusting anisotropic covariance metric. In an example of 2-dimensional velocity fields it is shown that regional compression and extension areas can be extracted.
Results indicate that the observed permafrost area has experienced a mean annual acceleration of about 0.1m/Year between the years 2013 and 2015. During the late summer months of 2015, a prominent temporal acceleration was observed. The mean displacement rate was found to be 0.67m/year, whereas the 3-dimensional displacement is dominated by a translation following the gliding surface. An area in the front of the observed field of view was found to have higher displacement rates, especially during the late summer months, thus it detaches from the otherwise relatively homogeneous flow field.
The methods and principles presented in this work show the potential of monitoring permafrost surface displacements using permanently installed optical cameras in combination with positioning results from permanently mounted GNSS stations. These principles can easily be transfered to other monitoring applications and thus contribute to a better understanding of such processes.Note de contenu : 1 Introduction
2 Study Site
3 Image-Based Displacement Estimation
4 Object Point Reconstruction
5 Collocation for Time Series Analysis
6 Results
7 Conclusions
8 OutlookNuméro de notice : 17458 Affiliation des auteurs : non IGN Autre URL associée : https://doi.org/10.3929/ethz-a-010865360 Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : thèse : Sciences : ETHZ : 2016 DOI : 10.3929/ethz-a-010865360 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-99.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89683 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 17458-01 33.60 Livre Centre de documentation Photogrammétrie - Lasergrammétrie Disponible Development of new hybrid geoid model for Japan, "GSIGEO2011" / Basara Miyahara in Bulletin of the GeoSpatial Information authority of Japan, vol 62 (December 2014)
[article]
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 GNSSRésumé : (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
in Bulletin of the GeoSpatial Information authority of Japan > vol 62 (December 2014) . - pp 11 - 20[article]On the computation of reliable formal uncertainties in the densification of GPS-levelling networks by least-squares collocation / E. Mysen in Journal of geodesy, vol 88 n° 10 (October 2014)
[article]
Titre : On the computation of reliable formal uncertainties in the densification of GPS-levelling networks by least-squares collocation Type de document : Article/Communication Auteurs : E. Mysen, Auteur Année de publication : 2014 Article en page(s) : pp 917 - 926 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Nivellement
[Termes IGN] collocation par moindres carrés
[Termes IGN] optimisation (mathématiques)
[Termes IGN] précisionRésumé : (Auteur) A realization of a height system covering the south of Norway has been performed, based on least-squares collocation applied to differences between geometric and gravimetric quasigeoid heights, inhomogeneous and isotropic covariance modelling, and without prior information on the error sources of the involved data types. As a result, the derived normal heights were biased by the systematic errors of the GPS-levelling network. The important covariance properties were determined at every location from spatially differenced observations, and made it straightforward to evaluate the uncertainties of the biased height reference. The distribution of predictions followed a Gaussian shape, but extreme realizations were overrepresented. Numéro de notice : A2014-514 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0732-x Date de publication en ligne : 01/06/2014 En ligne : https://doi.org/10.1007/s00190-014-0732-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74118
in Journal of geodesy > vol 88 n° 10 (October 2014) . - pp 917 - 926[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-2014101 SL Revue Centre de documentation Revues en salle Disponible GDQM-PL13 – the new gravimetric quasigeoid model for Poland / Malgorzata Szelachowska in Geoinformation issues, vol 6 n° 1 (2014)
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Titre : GDQM-PL13 – the new gravimetric quasigeoid model for Poland Type de document : Article/Communication Auteurs : Malgorzata Szelachowska, Auteur ; Jan Krynski, Auteur Année de publication : 2014 Article en page(s) : pp 5 - 19 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] anomalie de pesanteur
[Termes IGN] collocation par moindres carrés
[Termes IGN] données GNSS
[Termes IGN] géoïde gravimétrique
[Termes IGN] Pologne
[Termes IGN] quasi-géoïdeRésumé : (auteur) The new gravimetric quasigeoid model GDQM-PL13 for Poland was determined. The 1’×1’ mean Faye anomalies, deflections of the vertical for the territory of Poland, gravity anomalies from the neighbouring countries and the EGM2008 were used as input data. The remove-compute-restore (RCR) method and the least squares collocation approach with the planar logarithmic covariance function of gravity anomalies were applied. Height anomalies computed from the GDQM-PL13 have been compared with the corresponding ones obtained from GNSS/levelling data at the stations of the POLREF, EUVN and ASG-EUPOS networks and the precise GNSS/levelling control traverse. The new quasigeoid model was also compared with the gravimetric quasigeoid model GDQ08 developed in 2008 for the area of Poland, with the EGM2008, and with the most recent global geopotential model based on GOCE data. The results of the comparison were analysed and the accuracy of the GDQM-PL13 has been assessed and discussed. Numéro de notice : A2014-764 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans En ligne : http://www.igik.edu.pl/upload/File/wydawnictwa/GI6MSJK1.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=76834
in Geoinformation issues > vol 6 n° 1 (2014) . - pp 5 - 19[article]PermalinkAnalysis of long-term GPS observations in Greece (1993-2009) and geodynamic implications for the Eastern Mediterranean / Michael D. Müller (2011)PermalinkThe 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)PermalinkTuning a gravimetric quasigeoid to GPS-levelling by non-stationary least-squares collocation / N. Darbehesti in Journal of geodesy, vol 84 n° 7 (July 2010)PermalinkGravity gradient modeling using gravity and DEM / L. Zhu in Journal of geodesy, vol 83 n° 6 (June 2009)PermalinkMean dynamic topography and geostrophic surface currents in the Fram Strait derived from geodetic data / D. Lysaker in Marine geodesy, vol 32 n° 1 (January - March 2009)PermalinkAstronomical-topographic levelling using high-precision astrogeodetic vertical deflections and Digital Terrain Model data / C. Hirt in Journal of geodesy, vol 82 n° 4-5 (April - May 2008)PermalinkLeast-squares prediction in linear models with integer unknowns / Peter J.G. Teunissen in Journal of geodesy, vol 81 n° 9 (September 2007)PermalinkChamp de vitesses de l'ITRF, propriétés cinématiques de la croute terrestre et condition de non rotation globale / Juliette Legrand (2007)PermalinkChoix optimal d'un modèle analytique de covariance pour la validation des mesures gravimétriques par la méthode de collocation (application : nord de l'Algérie) / S.A. Benahmed Daho in XYZ, n° 108 (septembre - novembre 2006)Permalink