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Auteur Nadine Dessay
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Products and services of the Urban THEIA Scientific Expertise Centre / Anne Puissant (2022)
Titre : Products and services of the Urban THEIA Scientific Expertise Centre Type de document : Article/Communication Auteurs : Anne Puissant, Auteur ; Thibault Catry, Auteur ; Rémi Cresson, Auteur ; Nadine Dessay, Auteur ; Laurent Demagistri, Auteur ; Sébastien Gadal, Auteur ; Arnaud Le Bris , Auteur ; Kenji Ose, Auteur ; Benjamin Pillot, Auteur Editeur : Strasbourg : Université de Strasbourg Année de publication : 2022 Conférence : LPS 2022, ESA Living Planet Symposium 22/05/2022 27/05/2022 Bonn Allemagne programme sans actes Note générale : projet AIMCEE (Apport de l’Imagerie satellitaire Multi-Capteurs pour répondre aux Enjeux Environnementaux et sociétaux des socio-systèmes urbains) Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] données spatiotemporelles
[Termes IGN] image satellite
Résumé : (auteur) The THEIA data and services centre (www.theia-land.fr) is a consortium of 12 French public institutions involved in Earth observation and environmental sciences (CEA, CEREMA, CIRAD, CNES, IGN, INRA, CNRS, IRD, Irstea, Météo France, AgroParisTech, and ONERA). THEIA was initiated in 2012 with the objective of increasing the use of space data by the scientific community and the public actors. The first years allowed structuring the national science and user communities, pooling resources to facilitate access to data and processing capacities, federating various previously unrelated initiatives, and disseminating the French achievements nationally and internationally.
The THEIA Land Data and Services Centre (www.theia-land.fr) is a consortium of 12 French public institutions involved in Earth observation and environmental sciences (CEA, CEREMA, CIRAD, CNES, IGN, INRAE, CNRS, IRD, Irstea, Météo France, AgroParisTech, and ONERA). THEIA has been initiated with the objective of increasing the use of space data by the scientific community and the public actors. The Scientific Expertise Centers (SEC) cluster research groups on various thematic domains. The "Urban” SEC gathers experts in multi-sensor urban remote sensing. Researchers of this group have structured their works around the development of algorithms useful for urban remote sensing using optical and SAR sensors to propose “urban products” at three different spatial scales: (1) the urban footprint, (2) the urban fabrics and (3) the urban objects. The objective of this poster is to present recent (>2019) advances of the URBAN SEC at these three scales. For the first two, the proposed methods are adapted to the geographic context of urban cities (West Cities, South Cities first and North Cities). For each spatial scale, the objective is to propose validated scientific products already available or in the near-term through the THEIA Land Service and Data Infrastructure.
At the macro-scale (urban footprint), an unsupervised automated approach is currently under development at Espace-DEV - Montpellier, and funded by a CNES project (TOSCA DELICIOSA). This method is derived from the FOTO algorithm originally developed to differentiate vegetation textures in HR and VHR satellite images (Couteron et al. 2006, Lang et al., 2019). It has been optimized and packaged into the FOTOTEX Python Open-Source library. The method is very well suited for areas with no or few urban settlement data or with quickly growing informal settlements. No training dataset is required, and the urban footprint can be identified from only one satellite image as long as it is not covered by clouds. For Western Cities where training datasets are available, the Urba-Opt processing chain based on an automatic and object-oriented approach has been deployed on HPC infrastructure and produce annually (since 2018) an urban settlement product which is available through the A2S dissemination infrastructure and on the Urban SEC of Theia land data and service Infrastructure. An ongoing research between LIVE and Espace Dev Labs focused on the interest to use the FOTOTEX result as training data in the Urba-Opt processing chain to propose an updated product of urban settlement for South cities.
At the scales of urban fabrics, products are under research activities The LIVE lab. In the context of an ongoing PhD thesis (ANR TIMES) and Tosca project (CNES 2019-2022) Sentinel-2 single-date images are used to assess two semantic segmentation networks (U-Net) that we combined using feature fusion between a from scratch network and a pre-trained network on ImageNet. Three spectral or textural indices have been added to the both networks in order to improve the classification results. The results showed a performance gain for the fusion methods. The research activities are ongoing in order to test the S1 imagery and temporal series for training in a deep architecture.
The IGN-LaSTIG - Univ. Paris Est has focused on the use of Sentinel-2 and VHR mono-temporal SPOT products to retrieve land cover information related to urban density. First, images undergo a U-net based semantic segmentation at urban object level to retrieve ‘topographic’ classes (buildings, roads, vegetation, …). Generalized information about urban fabrics is then derived out of these land cover maps thanks to another CNN architecture. Both a building density measure and a simplified Urban Atlas like land cover map are calculated. The UMR ESPACE has focused on the machine learning modeling of the evolution of urban territories of Arctic (Yakutsk) and North-Eastern Europe (Baltic States and Kaliningrad) cities since the post-Soviet period at two scales: those of the built-up area with high spatial resolution SPOT 6/7 images, and of the urban structures based on the use of Landsat 5 TM, Landsat 8 OLI, and Sentinel 2 MSI images. Environmental (urban vegetation), economic (agricultural transformation), and morphometric indexes have been developed to characterize the processes of urban restructuring (densification, renovation) and expansion of post-Soviet cities. A comparative analysis of the machine learning algorithms used was done on the South-East Baltic cities to evaluate their performance.
At the scale of urban object (3), a map of building with their functions is proposed by the TETIS laboratory. The study targets the retrieval of buildings footprint using deep convolutional neural networks for semantic segmentation, from Spot-6/7 images (1,5m spacing), on the entire France mainland. A single model has been trained and validated from 1.2k Spot-6/7 scenes and 20M images patches. The LIVE Lab has focused on the detection of urban changes from tri-stereoscopic Pléiades imagery through 2017 to 2020. A processing chain based on a Random Forest classifiers (ImCLASS) has been tested and the impact of the height attribute to detect changes has been evaluated to characterize changes into three thematic classes of changes.
Numéro de notice : C2022-016 Affiliation des auteurs : UGE-LASTIG+Ext (2020- ) Thématique : IMAGERIE/INFORMATIQUE Nature : Poster nature-HAL : Poster-avec-CL DOI : sans En ligne : https://express.converia.de/frontend/index.php?page_id=22745&additions_conferenc [...] Format de la ressource électronique : URL article Permalink :
Products and services of the Urban THEIA Scientific Expertise Centre - posterAdobe Acrobat PDF
Fast unsupervised multi-scale characterization of urban landscapes based on Earth observation data / Claire Teillet in Remote sensing, vol 13 n° 12 (June-2 2021)
Titre : Fast unsupervised multi-scale characterization of urban landscapes based on Earth observation data Type de document : Article/Communication Auteurs : Claire Teillet, Auteur ; Benjamin Pillot, Auteur ; Thibault Catry, Auteur ; Laurent Demagistri, Auteur ; Dominique Lyszczarz, Auteur ; Marc Lang, Auteur ; Pierre Couteron, Auteur ; Nicolas Barbier, Auteur ; Arsène Adou Kouassi, Auteur ; Quentin Gunther , Auteur ; Nadine Dessay, Auteur Année de publication : 2021 Projets : GeoSud / , TOSCA / Article en page(s) : n° 2398 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Brasilia
[Termes IGN] caractérisation
[Termes IGN] Côte d'Ivoire
[Termes IGN] empreinte
[Termes IGN] image Pléiades-HR
[Termes IGN] image Sentinel-MSI
[Termes IGN] paysage urbain
[Termes IGN] texture d'image
[Termes IGN] zone urbaine
Résumé : (auteur) Most remote sensing studies of urban areas focus on a single scale, using supervised methodologies and very few analyses focus on the “neighborhood” scale. The lack of multi-scale analysis, together with the scarcity of training and validation datasets in many countries lead us to propose a single fast unsupervised method for the characterization of urban areas. With the FOTOTEX algorithm, this paper introduces a texture-based method to characterize urban areas at three nested scales: macro-scale (urban footprint), meso-scale (“neighbourhoods”) and micro-scale (objects). FOTOTEX combines a Fast Fourier Transform and a Principal Component Analysis to convert texture into frequency signal. Several parameters were tested over Sentinel-2 and Pleiades imagery on Bouake and Brasilia. Results showed that a single Sentinel-2 image better assesses the urban footprint than the global products. Pleiades images allowed discriminating neighbourhoods and urban objects using texture, which is correlated with metrics such as building density, built-up and vegetation proportions. The best configurations for each scale of analysis were determined and recommendations provided to users. The open FOTOTEX algorithm demonstrated a strong potential to characterize the three nested scales of urban areas, especially when training and validation data are scarce, and computing resources limited. Numéro de notice : A2021-505 Affiliation des auteurs : ENSG+Ext (2020- ) Autre URL associée : vers HAL Thématique : IMAGERIE/INFORMATIQUE/URBANISME Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/rs13122398 Date de publication en ligne : 19/06/2021 En ligne : https://doi.org/10.3390/rs13122398 Format de la ressource électronique : URL article Permalink :
in Remote sensing > vol 13 n° 12 (June-2 2021) . - n° 2398[article]