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Titre : Radar interferometry of unstable slopes : an application to rock glaciers Type de document : Mémoire Auteurs : Theeba Raveendran, Auteur Editeur : Champs-sur-Marne : Ecole nationale des sciences géographiques ENSG Année de publication : 2020 Importance : 31 p. Format : 21 x 30 cm Note générale : Bibliographie
Rapport de projet pluridisciplinaire, cycle ING2Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] Colorado (Etats-Unis)
[Termes IGN] données spatiotemporelles
[Termes IGN] image Sentinel-SAR
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] montagne
[Termes IGN] rocher
[Termes IGN] vitesse de déplacementIndex. décimale : PROJET Mémoires : Rapports de projet - stage des ingénieurs de 2e année Résumé : (Auteur) Le projet vise à calculer la vitesse de déplacement de glaciers rocheux par interférométrie radar à partir d’images radar acquises grâce à la constellation Sentinel-1 (ESA). Les images utilisées pour l’étude ont été acquises de juin à septembre 2018 et de juillet à octobre 2019. Les glaciers rocheux étudiés se situent au nord-est de Telluride, dans la chaîne de montagnes de San Juan, Colorado, Etats-Unis. La vitesse de déplacement des glaciers rocheux a déjà été quantifiée par photogrammétrie à partir d’images aériennes sur dix, vingt et trente ans. L’interférométrie radar (InSAR) apparaît donc comme une méthode complémentaire, permettant de mettre en évidence les déformations de l’ordre du millimètre à l’échelle d’une saison. De plus, ce projet permet aussi de manière générale d’évaluer la méthode InSAR pour l’étude des déplacements des glaciers rocheux. Les images ont été traitées à l’aide du logiciel libre de l’ESA, SNAP. La vitesse de déplacement des glaciers rocheux a été calculée sur une période de douze jours, aux étés 2018 et 2019. Six interférogrammes ont été réalisés pour cette étude. Les résultats finaux montrent que l’interférométrie radar permet bien de renforcer les résultats obtenus par photogrammétrie. Les glaciers rocheux étudiés ont des vitesses de déplacement allant de cinq millimètres à trois centimètres sur les périodes étudiées. On observe ainsi une accélération du déplacement à l’approche de l’hiver. Note de contenu :
Introduction
1. Context
1.1 Background
1.2 Study area
2. Source data
2.1 Sentinel-1 mission
2.2 Images
3. Processing
3.1 Principle of interferometry
3.2 Calculation of rock glaciers’ creep
4. Results and discussion
4.1 Displaying results
4.2 Analysis
ConclusionNuméro de notice : 26391 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Mémoire de projet pluridisciplinaire Organisme de stage : Université d’Oslo Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96068 Documents numériques
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Mémoire Radar interferometry of unstable slopes... - pdf auteurAdobe Acrobat PDFQuality control and new data-quality measures for the aesthetics of a Croatian topographic map at the scale of 1:25,000 / Branko Puceković in International journal of cartography, vol 3 n° 2 (December 2017)
Titre : Quality control and new data-quality measures for the aesthetics of a Croatian topographic map at the scale of 1:25,000 Type de document : Article/Communication Auteurs : Branko Puceković, Auteur ; Miljenko Lapaine, Auteur Année de publication : 2017 Article en page(s) : pp 187 - 200 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] 1:25.000
[Termes IGN] carte topographique
[Termes IGN] contrôle qualité
[Termes IGN] Croatie
[Termes IGN] esthétique cartographique
[Termes IGN] mesure de la qualité
[Termes IGN] représentation du relief
[Termes IGN] rocher
[Termes IGN] style cartographique
[Vedettes matières IGN] GéovisualisationRésumé : (auteur) A brief overview is given of the quality control of a 1:25,000 scale topographic map, carried out by the Croatian Geodetic Institute (CGI). As the topic of the aesthetics of the topographic map has, in the authors’ opinion, not been extensively covered, the paper concentrates on this topic. The paper focuses on devising an aesthetic standard relating mainly to the representation of relief. In fact, aesthetics can be controlled indirectly in terms of relief and water course alignment, the smoothness of contour lines, the non-existence of bonded contour lines and rock representation justification. A comparison between quality control at the CGI and quality elements according to contemporary standards was carried out. The presence of data-quality elements was registered in accordance with the ISO guidelines. A proposal for several data-quality measures for aesthetics related to relief representation is also given. Numéro de notice : A2017-685 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/23729333.2016.1278191 En ligne : https://doi.org/10.1080/01431161.2016.1252477 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=87349
in International journal of cartography > vol 3 n° 2 (December 2017) . - pp 187 - 200[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 : 33.60 Applications photogrammétriques - usage combiné de la photogrammétrie et de la lasergrammétrie 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
Titre : Design principles for Swiss-style rock drawing Type de document : Article/Communication Auteurs : Bernhard Jenny, Auteur ; Jürg Gilgen, Auteur ; Roman Geisthövel, Auteur Année de publication : 2014 Article en page(s) : pp 360-371 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rédaction cartographique
[Termes IGN] dessin assisté par ordinateur
[Termes IGN] dessin automatique
[Termes IGN] dessin cartographique
[Termes IGN] hachure
[Termes IGN] rocher
[Termes IGN] spécification
[Termes IGN] style cartographique
[Termes IGN] SwisstopoRésumé : (Auteur) Swiss-style rock drawing uses shaded hachures to show the characteristic forms and the third dimension of rocks and cliffs. Rock faces, trenches, gullies, faults and other rock features relevant for orientation and navigation in mountainous areas are shown as seen from the ground instead of from an orthogonal perspective. The density and dimensions of hachures change with the exposure to a source of illumination to generate a shading effect that highlights the terrain’s three-dimensionality. The generation of rock drawings in Swiss style is time-intensive and requires an eye for the artistic rendering of the terrain’s third dimension as well as an understanding of different rock types and their morphology. Design principles have not yet been documented in a detailed and comprehensive manner and only rudimentary algorithms exist for the digital generation of simplified representations. This paper discusses the defining characteristics and specific design principles of Swiss-style rock drawing based on figures and unpublished documentation from the Swiss Federal Office of Topography swisstopo. We identify three main types of hachure-based rock drawing and discuss graphical elements for the most common type. We also discuss the combination of rock drawings with contour lines, their generalisation and the drawing process. Numéro de notice : A2014-645 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75091
in Cartographic journal (the) > vol 51 n° 4 (November 2014) . - pp 360-371[article]Réservation
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Titre : Managing coppice forests for rockfall protection: lessons from modeling Type de document : Article/Communication Auteurs : Anna Radkte, Auteur ; David Toe, Auteur ; Frédéric Berger, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 485 - 494 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation
[Termes IGN] Autriche
[Termes IGN] effondrement de terrain
[Termes IGN] forêt
[Termes IGN] gestion des ressources
[Termes IGN] Italie
[Termes IGN] protection de l'environnement
[Termes IGN] rocher
[Termes IGN] taillisRésumé : (Auteur) • Context: One eighth of Europe’s forests are still managed as coppice. In some European countries, more than half of the forest exhibits coppice structures from the past or present coppice management. Many of these forests grow in the broadleaf zone of mountainous regions, often on steep slopes. Here, they play an important role in rockfall protection. However, it remains unclear how coppice forests should be structured for optimal rockfall protection or how the protection effect changes during the aging of the coppice.
• Aim: A few studies have applied rock trajectory analyses, but so far, no process-based model has been used to quantify the protective effect of differently structured coppice forests. The present study compared 40 coppice patches from two chronosequences in South Tyrol, North Italy, regarding their protective effect against rocks of two sizes using the rockfall simulation model Rockyfor3D.
• Results: The results indicate that coppice stands older than 30 years better protect against rockfall than medium-aged and young stands, although the old ones have lower stem densities. Surprisingly, a random stem distribution had a better protective effect than the clumped stem distribution typical for coppice stands.
• Conclusion: Implications for future management are discussed in detail, including the relevance of standards in coppice forests.Numéro de notice : A2014-285 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-013-0339-z date de publication en ligne : 30/10/2013 En ligne : https://doi.org/10.1007/s13595-013-0339-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=33188
in Annals of Forest Science > vol 71 n° 4 (June 2014) . - pp 485 - 494[article]Exemplaires (1)
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