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Generation of high-resolution orthomosaics from historical aerial photographs using Structure-from-motion and Lidar data / Ji Won Suh in Photogrammetric Engineering & Remote Sensing, PERS, vol 89 n° 1 (January 2023)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 89 n° 1 (January 2023) . - pp 37 - 46 Titre : Generation of high-resolution orthomosaics from historical aerial photographs using Structure-from-motion and Lidar data Type de document : Article/Communication Auteurs : Ji Won Suh, Auteur ; William Ouimet, Auteur Année de publication : 2023 Article en page(s) : pp 37 - 46 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie [Termes IGN] ArcGIS Desktop [Termes IGN] Connecticut (Etats-Unis) [Termes IGN] données lidar [Termes IGN] erreur moyenne quadratique [Termes IGN] estompage [Termes IGN] image ancienne [Termes IGN] MNS lidar [Termes IGN] orthophotoplan numérique [Termes IGN] photographie aérienne [Termes IGN] point d'appui [Termes IGN] structure-from-motion Résumé : (auteur) This study presents a method to generate historical orthomosaics using Structure-from-Motion (SfM ) photogrammetry, historical aerial photographs, and lidar data, and then analyzes the horizontal accuracy and factors that can affect the quality of historical orthoimagery products made with these approaches. Two sets of historical aerial photographs (1934 and 1951) were analyzed, focused on the town of Woodstock in Connecticut, U.S.A. Ground control points (GCPs) for georeferencing were obtained by overlaying multiple data sets, including lidar elevation data and derivative hillshades, and recent orthoimagery. Root-Mean-Square Error values of check points (CPs ) for 1934 and 1951 orthomosaics without extreme outliers are 0.83 m and 1.37 m, respectively. Results indicate that orthomosaics can be used for standard mapping and geographic information systems (GIS ) work according to the ASPRS 1990 accuracy standard. In addition, results emphasize that three main factors can affect the horizontal accuracy of orthomosaics: (1) types of CPs, (2) the number of tied photos, and (3) terrain. Numéro de notice : A2023-046 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.22-00063R2 Date de publication en ligne : 01/01/2023 En ligne : https://doi.org/10.14358/PERS.22-00063R2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102355 [article]

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Terrain representation using orientation / Gene Trantham in Cartography and Geographic Information Science, vol 49 n° 6 (November 2022)  

Public [article]  inCartography and Geographic Information Science > vol 49 n° 6 (November 2022) . - pp 479 - 491 Titre : Terrain representation using orientation Type de document : Article/Communication Auteurs : Gene Trantham, Auteur ; Patrick Kennelly, Auteur Année de publication : 2022 Article en page(s) : pp 479 - 491 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rédaction cartographique [Termes IGN] données matricielles [Termes IGN] estompage [Termes IGN] modèle numérique de surface [Termes IGN] ombre [Termes IGN] orientation [Termes IGN] représentation du relief [Termes IGN] teinte hypsométrique Résumé : (auteur) A terrain data model using orientation rather than elevation permits more efficient analysis and stores its data in a multi-band raster. Representation techniques from the computer graphics industry are readily adopted with this data model. A common data model for terrain surfaces–the raster digital elevation model (DEM)–carries with it limitations by emphasizing height. Derived products such as relief shading require additional processing to determine orientation, even though they are used more frequently than those relying on elevation (e.g. hypsometric tinting). We show some of the benefits of encoding and analyzing terrain based on surface orientation, an approach that uses normal vectors stored as multi-band raster, the data storage convention in the computer graphics industry. A change in the data model and the conceptualization of the surface’s defining characteristics allows relief shading methods to run faster than conventional tools. Processing efficiencies are especially useful for more advanced shading models that may employ hundreds of relief shading calculations. In addition, an orientation-focused approach to terrain permits cartographic techniques to parallel common computer graphics methods. This project explores one such method, normal-mapping, an effect that adds texture to conventional relief shading by perturbing surface normal vectors. Numéro de notice : A2022-844 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/15230406.2022.2035256 Date de publication en ligne : 03/03/2022 En ligne : https://doi.org/10.1080/15230406.2022.2035256 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102072 [article]

Initialization methods of convolutional neural networks for detection of image manipulations / Ivan Castillo Camacho (2021)  

Public Titre : Initialization methods of convolutional neural networks for detection of image manipulations Titre original : Méthodes d'initialisation des réseaux de neurones convolutifs pour la détection des manipulations d'images Type de document : Thèse/HDR Auteurs : Ivan Castillo Camacho, Auteur ; Kai Wang, Directeur de thèse Editeur : Grenoble [France] : Université Grenoble Alpes Année de publication : 2021 Importance : 145 p. Format : 21 x 30 cm Note générale : bibliographie Thèse pour obtenir le grade de Docteur de l'Université Grenoble, spécialité : signal, image, paroles, télécoms Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] altération [Termes IGN] apprentissage profond [Termes IGN] classification par réseau neuronal convolutif [Termes IGN] covariance [Termes IGN] détection d'anomalie [Termes IGN] estompage [Termes IGN] filtre passe-haut [Termes IGN] flux de données [Termes IGN] infraction [Termes IGN] manipulation de données [Termes IGN] qualité des données [Termes IGN] retouche [Termes IGN] variance Index. décimale : THESE Thèses et HDR Résumé : (auteur) Fake images and videos have engulfed mass communication media. This is not something recent, manipulations and forgeries have occurred since the advent of photography itself. These alterations can go from innocent retouches in an attempt to make an image visually attractive to the spread of misleading information or even the use of false media in legal instances. Accordingly, the creation of methods that can help us assure the authenticity of an image presented as non-modified is of paramount importance. In this thesis, we aim at detecting image manipulation operations using deep learning techniques. We present three methods showing the progression of our work under one common objective, i.e, the design and test of Convolutional Neural Network (CNN) initialization methods for image forensic problems with a variance stability focus for the output of a CNN layer.First, we carry out an extensive review of the state of the art in deep-learning-based methods for image forensics. From this review we can confirm that the first layer of a CNN has big impact on the final performance. Specifically, the initialization used on the first-layer filters plays an important role that should be in line with the image forensic task in hand.As our first attempt to address this research problem, we propose a low-complexity initialization method for CNNs. Taking advantage of previous methods designed for the computer vision field, we extend the popular Xavier method to design a filter that would provide variance stability after a convolution operation. This method generates a set of random high-pass filters for the initialization of a CNN's first layer. These filters allow us to better identify forensic traces which usually lie towards the high-frequency part of the image.This first approach constitutes a good staring point of our work. However, a wrong assumption, largely utilized in the research community, was made. This is corrected in our second method where we follow a different data-dependent approach and take into consideration the real statistical properties of natural images. Accordingly, we propose a scaling method for first-layer filters which can cope well with different CNN initialization algorithms. The objective remains in keeping the stability of the variance of data flow in a CNN. We also present theoretical and experimental studies on the output variance for convolutional filter, which are the basis of our proposed data-dependent scaling.Next we describe a revisited version of our first proposal now with a corrected assumption on the statistics of natural images. More precisely, we propose an improved random high-pass initialization method which does not explicitly compute the statistics of input data. We believe that such a ``data-independent'' approach has higher flexibility and broader application range than our second method in situations where the computation of input statistics is not possible.Our proposed methods are tested over several image forensic problems and different CNN architectures.Finally, during all this thesis work we took part in a challenge competition of image forgery detection organized by the French National Research Agency and the French Directorate General of Armaments. We explain in the Appendix the objectives of the challenge along with a brief description of our work conducted for the competition. Note de contenu : 1- Introduction 2- Background knowledge and state of the art 3- Random high-pass initialization 4- Data-dependent initialization 5- Revisiting the random high-pass initialization 6- Conclusions and perspectives Numéro de notice : 28437 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : signal, image, paroles, télécoms : Grenoble : 2021 DOI : sans En ligne : https://tel.archives-ouvertes.fr/tel-03346063/document Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98833

Automated Swiss-style relief shading and rock hachuring / Roman Geisthövel in Cartographic journal (the), Vol 55 n° 4 (November 2018)  

Public [article]  inCartographic journal (the) > Vol 55 n° 4 (November 2018) . - pp 341 - 361 Titre : Automated Swiss-style relief shading and rock hachuring Type de document : Article/Communication Auteurs : Roman Geisthövel, Auteur ; Lorenz Hurni, Auteur Année de publication : 2018 Article en page(s) : pp 341 - 361 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rédaction cartographique [Termes IGN] carte topographique [Termes IGN] cartographie étrangère [Termes IGN] estompage analytique [Termes IGN] généralisation cartographique [Termes IGN] représentation du relief [Termes IGN] style cartographique [Termes IGN] Suisse Résumé : (Auteur) Rock depiction in Swiss topographic maps has evolved from humble line drawings into expressive renderings indicating slope, aspect and traversability. In this paper, an automatic method to derive monochrome Swiss-style rock hachures from a raster elevation model is presented. The proper placement and light modulation of the linear strokes depend on the availability of sound foundations for both terrain generalization and relief shading, for which two novel methods are introduced. The generalization applies line integral convolution along slope lines to the elevation values. The resulting smoothed raster has the footprint of its steep faces enlarged to increase the map space available for steep faces. The shaded relief is generated with the focus on terrain edges, unlike common raster cell-based methods. The rock hachures are modulated according to the grey values of the shaded relief. Finally, we present two topographic maps that demonstrate this new method of depicting relief. Numéro de notice : A2018-592 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00087041.2018.1551955 Date de publication en ligne : 01/03/2019 En ligne : https://doi.org/10.1080/00087041.2018.1551955 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92566 [article]

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A method of downscaling temperature maps based on analytical hillshading for use in species distribution modelling / Ángel M. Felicísimo in Cartography and Geographic Information Science, Vol 45 n° 4 (July 2018)  

Public [article]  inCartography and Geographic Information Science > Vol 45 n° 4 (July 2018) . - pp 329 - 338 Titre : A method of downscaling temperature maps based on analytical hillshading for use in species distribution modelling Type de document : Article/Communication Auteurs : Ángel M. Felicísimo, Auteur ; Miguel A. Martín-Tardío, Auteur Année de publication : 2018 Article en page(s) : pp 329 - 338 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie thématique [Termes IGN] carte climatique [Termes IGN] carte thématique [Termes IGN] distribution spatiale [Termes IGN] estompage analytique [Termes IGN] image Landsat-8 [Termes IGN] modèle numérique de terrain [Termes IGN] rayonnement solaire [Termes IGN] température Résumé : (Auteur) Climate maps have been widely used for the construction of species distribution models. These maps derive from interpolation of data collected by meteorological stations. The sparse distribution of stations generates maps with coarse spatial resolution that are unable to detect microclimates or areas that can serve as plant or animal refuges. This work proposes a method for downscaling temperature maps using the solar radiation falling upon hillsides as predictor for the influence of relief on local variability. Solar irradiance is estimated from a digital elevation model of the study area using a routine based on analytical hillshading. Some examples of downscaling from 1 km to 25 m spatial resolution are shown. The results are compared with the surface temperature maps from Landsat 8 satellite imagery. Numéro de notice : A2018-134 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/15230406.2017.1338620 Date de publication en ligne : 19/06/2017 En ligne : https://doi.org/10.1080/15230406.2017.1338620 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89666 [article]

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Progressive block graying and landmarks enhancing as intermediate representations between buildings and urban areas / Guillaume Touya (2017) 

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Perceptually shaded slope maps for the visualization of digital surface models / Thomas J. Pingel in Cartographica, vol 49 n° 4 (Winter 2014)  

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Changing the light azimuth in shaded relief representation by clustering aspect / Fabio Veronesi in Cartographic journal (the), vol 51 n° 4 (November 2014)  

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Effects of cartographic elevation visualizations and map-reading tasks on eye movements / Katja Putto in Cartographic journal (the), vol 51 n° 3 (August 2014)  

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Landscape preference and map readability in design evaluation of topographic maps with an orthoimage background / Paulo Raposo in Cartographic journal (the), vol 51 n° 1 (February 2014)  

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Visual abstraction and stylisation of maps / Tobias Isenberg in Cartographic journal (the), vol 50 n° 1 (February 2013)  

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Multidirectional visibility index for analytical shading enhancement / T. Podobnikar in Cartographic journal (the), vol 49 n° 3 (August 2012)  

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Automated reduction of visual complexity in small-scale relief shading / A. Leonowicz in Cartographica, vol 45 n° 1 (March 2010)  

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Swiss-style colour relief shading modulated by elevation and by exposure to illumination / Bernhard Jenny in Cartographic journal (the), vol 43 n° 3 (December 2006)  

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A uniform sky illumination model to enhance shading of terrain and urban areas / Patrick Kennelly in Cartography and Geographic Information Science, vol 33 n° 1 (January 2006)  

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