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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 Phytosociological analysis of alpine swards and heathlands (pioneer patches) on ridges and peaks in the Julian Alps (NW Slovenia) / Igor Dakskobler in Hacquetia, vol 16 n° 1 (January 2017)
[article]
Titre : Phytosociological analysis of alpine swards and heathlands (pioneer patches) on ridges and peaks in the Julian Alps (NW Slovenia) Type de document : Article/Communication Auteurs : Igor Dakskobler, Auteur ; Bostjan Surina, Auteur Année de publication : 2017 Article en page(s) : pp 49 - 171 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Alpes
[Termes IGN] parc naturel national
[Termes IGN] phytosociologie
[Termes IGN] Slovénie
[Termes IGN] unité phytosociologique
[Vedettes matières IGN] Ecologie forestièreRésumé : (auteur) We conducted a phytosociological analysis of more than 250 relevés in the Julian Alps and compared them with similar communities elsewhere in the Alps and in the Dinaric Alps to describe the following new syntaxa of alpine swards and heathlands from the alliance Caricion firmae (class Elyno-Seslerietea): Saxifrago squarrosae-Caricetum mucronatae, Saussureo pygmaeae-Caricetum rupestris, Seslerio sphaerocephalae-Dryadetum octopetalae, Homogyno discoloris-Vaccinietum gaultherioidis, Saxifrago paniculatae-Caricetum fuliginosae and Homogyno discoloris-Loiseleurietum caricetosum firmae, the new association Achilleo clavennae-Elynetum myosuroidis from the alliance Oxytropido-Elynion and two new syntaxa from the alliance Loiseleurio-Vaccinion (class Loiseleurio-Vaccinietea): Homogyno alpinae-Vaccinietum gaultherioidis and Empetro-Vaccinietum gaultherioidis rhododendretosum hirsuti. Many species that are rare, of conservation concern or protected in Slovenia occur in the newly described communities. Numéro de notice : A2017-003 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1515/hacq-2016-0022 En ligne : https://doi.org/10.1515/hacq-2016-0022 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83414
in Hacquetia > vol 16 n° 1 (January 2017) . - pp 49 - 171[article]Imaging the internal structure of an alpine glacier via L-band airborne SAR tomography / Stefano Tebaldini in IEEE Transactions on geoscience and remote sensing, vol 54 n° 12 (December 2016)
[article]
Titre : Imaging the internal structure of an alpine glacier via L-band airborne SAR tomography Type de document : Article/Communication Auteurs : Stefano Tebaldini, Auteur ; Thomas Nagler, Auteur ; Helmut Rott, Auteur ; Achim Heilig, Auteur Année de publication : 2016 Article en page(s) : pp 7197 - 7209 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] Alpes
[Termes IGN] Autriche
[Termes IGN] bande L
[Termes IGN] données localisées 3D
[Termes IGN] image aérienne
[Termes IGN] image radar moirée
[Termes IGN] radar pénétrant GPR
[Termes IGN] tomographie radarRésumé : (Auteur) In this paper, we report results from the analysis of 3-D L-band airborne synthetic aperture radar (SAR) acquisitions acquired in March 2014 over the Mittelbergferner glacier, Austrian Alps, during the European Space Agency (ESA) campaign AlpTomoSAR. The campaign included coincident in situ measurements of snow and ice properties and ground-penetrating radar (GPR) data acquired at 600 and 200 MHz over a total length of 18 km. Radar data were acquired by repeatedly flying an L-band SAR along an oval racetrack at an altitude of about 1300 m over the glacier, such that two data stacks from opposite views are obtained. Data from all passes were coherently combined to achieve 3-D resolution capabilities, resulting in the generation of 3-D tomographic SAR (TomoSAR) cubes, where each voxel represents L-band radar reflectivity from a particular location in the 3-D space at a spatial resolution on the order of meters. TomoSAR cubes were finally corrected to account for wave propagation velocity into the ice, which was a necessary step to associate the observed features with their geometrical location, hence enabling a direct comparison to GPR data. The TomoSAR cubes show the complexity of the glacier subsurface scattering. Most areas are characterized by surface scattering in proximity of the ice surface, plus a complex pattern of in-depth volumetric scattering beneath and scattering at the ice/bedrock interface. Various subsurface features observed in GPR transects at 200 MHz clearly showed up in TomoSAR sections as well, particularly firn bodies, crevasses, layer transitions, and bedrock reflection down to 50 m below the ice surface. Numéro de notice : A2016-927 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2016.2597361 En ligne : https://doi.org/10.1109/TGRS.2016.2597361 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83341
in IEEE Transactions on geoscience and remote sensing > vol 54 n° 12 (December 2016) . - pp 7197 - 7209[article]The open data HELI-DEM DTM for the western alpine area: computation and publication / L. Biagi in Applied geomatics, vol 8 n° 3-4 (December 2016)
[article]
Titre : The open data HELI-DEM DTM for the western alpine area: computation and publication Type de document : Article/Communication Auteurs : L. Biagi, Auteur ; S. Caldera, Auteur ; L. Carcano, Auteur ; Marco Negretti, Auteur Année de publication : 2016 Article en page(s) : pp 191 - 200 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] Alpes
[Termes IGN] données altimétriques
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] European Terrestrial Reference Frame
[Termes IGN] fusion de données
[Termes IGN] Italie
[Termes IGN] modèle numérique de surface
[Termes IGN] Suisse
[Termes IGN] transformation rapide de FourierRésumé : (Auteur) Two problems can arise in analyzing Digital Elevation Models (DEMs). Firstly, one interest region could be patched by several partly overlapping models that present similar accuracies and spatial resolutions; they should be merged in one unified model. Moreover, even when the interest region is completely covered by one model, local data with better accuracy could cover partial areas and should be properly merged. All these problems have been addressed within Helvetia-Italy Digital Elevation Model, a project funded by the European Regional Development Fund (ERDF). One specific aim of the project was the creation and the publication of a unified DEM for a part of the Alps between Italy and Switzerland. The interest area is prevalently mountainous, with elevations that range from about 200 to 4600 m. Various elevation datasets were available that were gridded with different spatial resolutions, in different reference frames and coordinates. Moreover, one high resolution LiDAR model was available for some areas. Firstly, a validation was performed that allowed the identification of few blunders and confirmed the general accuracy of the input data. Two DEMs have been produced. Both of them cover the whole project area (boundaries λ = 7.80° East and λ = 10.70° East, φ = 45.10° North and φ = 46.70° North) and are gridded in ETRF2000 geographical coordinates, with a spatial resolution of 2 × 10−4 degrees. The former (named HD-1) has been obtained by interpolating and merging all the low resolution models on a new common grid. HD-1 has been locally corrected by the LiDAR model, where it was available; to avoid sharp discontinuities, the corrections have been filtered by Fast Fourier Transform before applying them. The resulting model has been called HD-2. HD-1 and HD-2 are published by an open access geoservice. Numéro de notice : A2016--054 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1007/s12518-016-0176-5 Date de publication en ligne : 26/10/2016 En ligne : http://dx.doi.org/10.1007/s12518-016-0176-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84201
in Applied geomatics > vol 8 n° 3-4 (December 2016) . - pp 191 - 200[article]Effects of forest structure and airborne laser scanning point cloud density on 3D delineation of individual tree crowns / Kaja Kandare in European journal of remote sensing, vol 49 n° 1 (2016)
[article]
Titre : Effects of forest structure and airborne laser scanning point cloud density on 3D delineation of individual tree crowns Type de document : Article/Communication Auteurs : Kaja Kandare, Auteur ; Hans Ole Ørka, Auteur ; Jonathan Cheung-Wai Chan, Auteur ; Michele Dalponte, Auteur Année de publication : 2016 Article en page(s) : pp 337 - 359 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] Alpes
[Termes IGN] délimitation
[Termes IGN] densité des points
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] forêt alpestre
[Termes IGN] houppier
[Termes IGN] Italie
[Termes IGN] semis de points
[Termes IGN] structure d'un peuplement forestierRésumé : (auteur) This paper presents a 3D delineation method for airborne laser scanning point cloud. The method is based on an unsupervised clustering technique applied on horizontal slices followed by vertical merging based on overlapping among clusters. On an Alpine forest dataset, we analysed the effects of different forest structures and point cloud densities on tree crown delineation. Forest structure affects mainly the omission error, which eases with homogeneous tree spacing and sizes, while on the commission error forest structure has only slight effect. Delineation accuracy increases with higher point densities where Mann-Whitney-Wilcoxon test shows that accuracy differences between thinned data and original data are statistically significant. Numéro de notice : A2016-829 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.5721/EuJRS20164919 En ligne : http://dx.doi.org/10.5721/EuJRS20164919 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82709
in European journal of remote sensing > vol 49 n° 1 (2016) . - pp 337 - 359[article]Une frontière pour les Pyrénées : l'épisode trop méconnu de la commission topographique franco-espagnole Caro-Ornano / Jean-Yves Puyo in Cartes & Géomatique, n° 228 (juin - août 2016)PermalinkTwo new montane grassland communities from the SE Alps (N Slovenia) / Igor Dakskobler in Hacquetia, vol 15 n° 1 (June 2016)Permalink14 years of GPS tropospheric delays in the French–Italian border region : comparisons and first application in a case study / Domenico Sguerso in Applied geomatics, vol 8 n° 1 (March 2016)PermalinkImage based geo-localization in the Alps / Olivier Saurer in International journal of computer vision, vol 116 n° 3 (February 2016)PermalinkCartographier et décrire la péninsule Ibérique : l'héritage militaire français (1808-1823) / Jean-Yves Puyo in Annales de géographie, n° 707 (janvier - février 2016)PermalinkXylem and soil CO2 fluxes in a Quercus pyrenaica Willd. coppice: root respiration increases with clonal size / Roberto Salomón in Annals of Forest Science, vol 72 n° 8 (December 2015)PermalinkMapping slope movements in Alpine environments using TerraSAR-X interferometric methods / Chloé Barboux in ISPRS Journal of photogrammetry and remote sensing, vol 109 (November 2015)PermalinkImpact of the North Atlantic oscillation on Southern Europe water distribution: insights from geodetic data / Pierre Valty in Earth Interactions, vol 19 n° 10 (September 2015)PermalinkApplication of archival aerial photogrammetry to quantify climate forcing of alpine landscapes / Natan Micheletti in Photogrammetric record, vol 30 n° 150 (June - August 2015)PermalinkLes Alpes d'Helbronner / Daniel Léon (2015)PermalinkMapping the value of ecosystem services: A case study from the Austrian Alps / Alessandro Paletto in Annals of forest research, vol 58 n° 1 (January 2015)PermalinkIs generalisation of uneven-aged management in mountain forests the key to improve biodiversity conservation within forest landscape mosaics? / M. Redon in Annals of Forest Science, vol 71 n° 7 (October 2014)PermalinkAssessing changes in species distribution from sequential large-scale forest inventories / Laura Hernandez in Annals of Forest Science, vol 71 n° 2 (March 2014)PermalinkDonnées géographiques et construction institutionnelle d’une région transnationale. Le SOIA comme objet-frontière ? / Raphael Pieroni in Revue internationale de géomatique, vol 24 n° 1 (mars – mai 2014)PermalinkPlusieurs scanners pour surveiller une rampe / Vincent Barras in Géomatique suisse, vol 112 n° 2 (01/02/2014)PermalinkPermalinkPermalinkHigh resolution DEM generation in high-alpine terrain using airborne remote sensing techniques / Y. Bühler in Transactions in GIS, vol 16 n° 5 (October 2012)PermalinkA method for extracting burned areas from Landsat TM/ETM+ images by soft aggregation of multiple Spectral Indices and a region growing algorithm / D. Stroppiana in ISPRS Journal of photogrammetry and remote sensing, vol 69 (April 2012)PermalinkA la limite du plateau provençal et de la montagne alpine, là vivaient d'anciens peuples appelés Ligures / Roger Verdegen (2012)Permalink