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A regional spatiotemporal analysis of large magnitude snow avalanches using tree rings / Erich Peitzsch in Natural Hazards and Earth System Sciences, Vol 21 n° 2 (February 2021)
[article]
Titre : A regional spatiotemporal analysis of large magnitude snow avalanches using tree rings Type de document : Article/Communication Auteurs : Erich Peitzsch, Auteur ; Jordi Hendrikx, Auteur ; Daniel Stahle, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 533 - 557 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] analyse diachronique
[Termes IGN] avalanche
[Termes IGN] Canada
[Termes IGN] cerne
[Termes IGN] croissance des arbres
[Termes IGN] dendrochronologie
[Termes IGN] données topographiques
[Termes IGN] échantillonnage
[Termes IGN] Etats-Unis
[Termes IGN] géomorphologie locale
[Termes IGN] magnitude
[Termes IGN] montagneRésumé : (auteur) Snow avalanches affect transportation corridors and settlements worldwide. In many mountainous regions, robust records of avalanche frequency and magnitude are sparse or non-existent. However, dendrochronological methods can be used to fill this gap and infer historical avalanche patterns. In this study, we developed a tree-ring-based avalanche chronology for large magnitude avalanche events (size ≥∼D3) using dendrochronological techniques for a portion of the US northern Rocky Mountains. We used a strategic sampling design to examine avalanche activity through time and across nested spatial scales (i.e., from individual paths, four distinct subregions, and the region). We analyzed 673 samples in total from 647 suitable trees collected from 12 avalanche paths from which 2134 growth disturbances were identified over the years 1636 to 2017 CE. Using existing indexing approaches, we developed a regional avalanche activity index to discriminate avalanche events from noise in the tree-ring record. Large magnitude avalanches, common across the region, occurred in 30 individual years and exhibited a median return interval of approximately 3 years (mean = 5.21 years). The median large magnitude avalanche return interval (3–8 years) and the total number of avalanche years (12–18) varies throughout the four subregions, suggesting the important influence of local terrain and weather factors. We tested subsampling routines for regional representation, finding that sampling 8 random paths out of a total of 12 avalanche paths in the region captures up to 83 % of the regional chronology, whereas four paths capture only 43 % to 73 %. The greatest value probability of detection for any given path in our dataset is 40 %, suggesting that sampling a single path would capture no more than 40 % of the regional avalanche activity. Results emphasize the importance of sample size, scale, and spatial extent when attempting to derive a regional large magnitude avalanche event chronology from tree-ring records. Numéro de notice : A2021-169 Affiliation des auteurs : non IGN Thématique : FORET/GEOMATIQUE Nature : Article DOI : 10.5194/nhess-21-533-2021 Date de publication en ligne : 05/02/2021 En ligne : https://doi.org/10.5194/nhess-21-533-2021 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97108
in Natural Hazards and Earth System Sciences > Vol 21 n° 2 (February 2021) . - pp 533 - 557[article]Topoclimatic zoning of continental Chile / Donna Cortez in Journal of maps, vol 17 n° 2 (February 2021)
[article]
Titre : Topoclimatic zoning of continental Chile Type de document : Article/Communication Auteurs : Donna Cortez, Auteur ; Sebastián Herrera, Auteur ; Daniela Araya-Osses, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : *pp 114 - 124 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] analyse de groupement
[Termes IGN] analyse en composantes principales
[Termes IGN] carte climatique
[Termes IGN] Chili
[Termes IGN] climat continental
[Termes IGN] climat de montagne
[Termes IGN] climatologie
[Termes IGN] littoral
[Termes IGN] partition d'image
[Termes IGN] topographie localeRésumé : (article) In this study, the topoclimates of continental Chile are mapped. The mapping involves the identification of homogeneous zones based on the relationships between the climatic variables that characterize a location and the topography that influences the spatial behavior of these variables. The climatic and topographical zoning of the study area is conducted using a statistical methodology based on a combination of principal component analysis and cluster analysis. The climate, topography, and topoclimatic zoning yield 20, 8, and 96 clusters, respectively. Maximum topoclimatic variability is identified in sectors with mountain ranges and intermediate depression (especially in valley areas), and minimum variability is detected in the coastal sector. Furthermore, only one of the topoclimatic units has an area larger than 50,000 km2, whereas 46.8% of the units have surface areas below 2,000 km2. Numéro de notice : A2021-410 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/17445647.2021.1886188 Date de publication en ligne : 10/03/2021 En ligne : https://doi.org/10.1080/17445647.2021.1886188 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97732
in Journal of maps > vol 17 n° 2 (February 2021) . - *pp 114 - 124[article]Using automated vegetation cover estimation from close-range photogrammetric point clouds to compare vegetation location properties in mountain terrain / R. Niederheiser in GIScience and remote sensing, vol 58 n° 1 (February 2021)
[article]
Titre : Using automated vegetation cover estimation from close-range photogrammetric point clouds to compare vegetation location properties in mountain terrain Type de document : Article/Communication Auteurs : R. Niederheiser, Auteur ; M. Winkler, Auteur ; V. Di Cecco, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 120 - 137 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie terrestre
[Termes IGN] Alpes
[Termes IGN] caméra numérique
[Termes IGN] carte de la végétation
[Termes IGN] classification par forêts d'arbres décisionnels
[Termes IGN] classification semi-dirigée
[Termes IGN] couvert végétal
[Termes IGN] distribution de Poisson
[Termes IGN] données topographiques
[Termes IGN] indice de végétation
[Termes IGN] module linéaire
[Termes IGN] montagne
[Termes IGN] occupation du sol
[Termes IGN] photogrammétrie métrologique
[Termes IGN] semis de pointsRésumé : (auteur) In this paper we present a low-cost approach to mapping vegetation cover by means of high-resolution close-range terrestrial photogrammetry. A total of 249 clusters of nine 1 m2 plots each, arranged in a 3 × 3 grid, were set up on 18 summits in Mediterranean mountain regions and in the Alps to capture images for photogrammetric processing and in-situ vegetation cover estimates. This was done with a hand-held pole-mounted digital single-lens reflex (DSLR) camera. Low-growing vegetation was automatically segmented using high-resolution point clouds. For classifying vegetation we used a two-step semi-supervised Random Forest approach. First, we applied an expert-based rule set using the Excess Green index (ExG) to predefine non-vegetation and vegetation points. Second, we applied a Random Forest classifier to further enhance the classification of vegetation points using selected topographic parameters (elevation, slope, aspect, roughness, potential solar irradiation) and additional vegetation indices (Excess Green Minus Excess Red (ExGR) and the vegetation index VEG). For ground cover estimation the photogrammetric point clouds were meshed using Screened Poisson Reconstruction. The relative influence of the topographic parameters on the vegetation cover was determined with linear mixed-effects models (LMMs). Analysis of the LMMs revealed a high impact of elevation, aspect, solar irradiation, and standard deviation of slope. The presented approach goes beyond vegetation cover values based on conventional orthoimages and in-situ vegetation cover estimates from field surveys in that it is able to differentiate complete 3D surface areas, including overhangs, and can distinguish between vegetation-covered and other surfaces in an automated manner. The results of the Random Forest classification confirmed it as suitable for vegetation classification, but the relative feature importance values indicate that the classifier did not leverage the potential of the included topographic parameters. In contrast, our application of LMMs utilized the topographic parameters and was able to reveal dependencies in the two biomes, such as elevation and aspect, which were able to explain between 87% and 92.5% of variance. Numéro de notice : A2021-258 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/15481603.2020.1859264 Date de publication en ligne : 13/01/2021 En ligne : https://doi.org/10.1080/15481603.2020.1859264 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97295
in GIScience and remote sensing > vol 58 n° 1 (February 2021) . - pp 120 - 137[article]Using Sentinel-2 images to estimate topography, tidal-stage lags and exposure periods over large intertidal areas / José P. Granadeiro in Remote sensing, Vol 13 n° 2 (January-2 2021)
[article]
Titre : Using Sentinel-2 images to estimate topography, tidal-stage lags and exposure periods over large intertidal areas Type de document : Article/Communication Auteurs : José P. Granadeiro, Auteur ; João Belo, Auteur ; Mohamed Henriques, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 320 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] bathymétrie
[Termes IGN] carte bathymétrique
[Termes IGN] écosystème
[Termes IGN] estran
[Termes IGN] Guinée-Bissao
[Termes IGN] habitat (nature)
[Termes IGN] image Sentinel-MSI
[Termes IGN] modèle numérique de surface
[Termes IGN] régression logistique
[Termes IGN] topographie localeRésumé : (auteur) Intertidal areas provide key ecosystem services but are declining worldwide. Digital elevation models (DEMs) are important tools to monitor the evolution of such areas. In this study, we aim at (i) estimating the intertidal topography based on an established pixel-wise algorithm, from Sentinel-2 MultiSpectral Instrument scenes, (ii) implementing a set of procedures to improve the quality of such estimation, and (iii) estimating the exposure period of the intertidal area of the Bijagós Archipelago, Guinea-Bissau. We first propose a four-parameter logistic regression to estimate intertidal topography. Afterwards, we develop a novel method to estimate tide-stage lags in the area covered by a Sentinel-2 scene to correct for geographical bias in topographic estimation resulting from differences in water height within each image. Our method searches for the minimum differences in height estimates obtained from rising and ebbing tides separately, enabling the estimation of cotidal lines. Tidal-stage differences estimated closely matched those published by official authorities. We re-estimated pixel heights from which we produced a model of intertidal exposure period. We obtained a high correlation between predicted and in-situ measurements of exposure period. We highlight the importance of remote sensing to deliver large-scale intertidal DEM and tide-stage data, with relevance for coastal safety, ecology and biodiversity conservation. Numéro de notice : A2021-197 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/IMAGERIE Nature : Article DOI : 10.3390/rs13020320 Date de publication en ligne : 19/01/2021 En ligne : https://doi.org/10.3390/rs13020320 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97148
in Remote sensing > Vol 13 n° 2 (January-2 2021) . - n° 320[article]Apport des méthodes : imagerie drone, LiDAR et imagerie hyperspectrale pour l’étude du littoral vendéen / Mathis Baudis (2021)
Titre : Apport des méthodes : imagerie drone, LiDAR et imagerie hyperspectrale pour l’étude du littoral vendéen Type de document : Mémoire Auteurs : Mathis Baudis, Auteur Editeur : Le Mans : Ecole Supérieure des Géomètres et Topographes ESGT Année de publication : 2021 Importance : 58 p. Format : 21 x 30 cm Note générale : bibliographie
Mémoire présenté en vue d'obtenir le diplôme d'ingénieur ESGT, spécialité Géomètre et TopographeLangues : Français (fre) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] image captée par drone
[Termes IGN] image hyperspectrale
[Termes IGN] littoral atlantique (France)
[Termes IGN] modèle numérique de terrain
[Termes IGN] orthophotoplan numérique
[Termes IGN] orthorectification
[Termes IGN] semis de points
[Termes IGN] trait de côte
[Termes IGN] Vendée (85)Index. décimale : ESGT Mémoires d'ingénieurs de l'ESGT Résumé : (auteur) L’érosion des falaises soulève de plus en plus de problématiques. Il existe de nombreuses études qualitatives sur ce sujet. Ici, l’objectif est de faire une étude quantitative sur le littoral vendéen. Nous allons étudier l’évolution du trait de côte, un épisode érosif fort : la chute d’une arche et l’apport de l’orthorectification d’images hyperspectrales. L’objectif est de coupler les acquisitions issues de drone, de LiDAR terrestre et de caméra hyperspectrale dans le but d’étudier le littoral vendéen. Note de contenu : Introduction
1- Etat des connaissances sur le littoral vendéen
2- Outils et méthodes
3- Présentation des résultats des différents traitements
4- Discussion sur les résultats
ConclusionNuméro de notice : 28695 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Mémoire ingénieur ESGT En ligne : https://dumas.ccsd.cnrs.fr/MEMOIRES-CNAM/dumas-03533799v1 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100466 Beach morphology and its dynamism from remote sensing for coastal management support / Carlos Cabezas Rabadán (2021)PermalinkContribution des SIG et de la modélisation volumique à la caractérisation géomorphologique et géologique de la région des Doukkala « Meseta côtière, Maroc » / Youness Ahmed Laaziz (2021)PermalinkPermalinkDéveloppement d’outils d’exploitation des archives photographiques aériennes de l’IGN pour caractériser l’évolution pluridécennale du littoral sur l’île de la Réunion / Adinane Oladjidé Ayichemi (2021)PermalinkDynamics of inundation events in the rivers-estuaries-ocean continuum in Bengal delta : synergy between hydrodynamic modelling and spaceborne remote sensing / Md Jamal Uddin Kahn (2021)PermalinkElevation models for reproducible evaluation of terrain representation / Patrick Kennelly in Cartography and Geographic Information Science, vol 48 n° 1 (January 2021)PermalinkGeomorphic analysis of Xiadian buried fault zone in Eastern Beijing plain based on SPOT image and unmanned aerial vehicle (UAV) data / Yanping Wang in Geomatics, Natural Hazards and Risk, vol 12 n° 1 (2021)PermalinkPermalinkPermalinkModélisation et raisonnement spatial flou pour l’aide à la localisation de victimes en montagne / Mattia Bunel (2021)Permalink