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Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations / Li Zhang in Journal of applied geodesy, vol 14 n° 2 (April 2020)  

Public [article]  inJournal of applied geodesy > vol 14 n° 2 (April 2020) . - pp 167 – 175 Titre : Reducing multipath effect of low-cost GNSS receivers for monitoring by considering temporal correlations Type de document : Article/Communication Auteurs : Li Zhang, Auteur ; Volker Schwieger, Auteur Année de publication : 2020 Article en page(s) : pp 167 – 175 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes descripteurs IGN] atténuation du signal [Termes descripteurs IGN] corrélation temporelle [Termes descripteurs IGN] coût [Termes descripteurs IGN] itération [Termes descripteurs IGN] ligne de base [Termes descripteurs IGN] oscillation [Termes descripteurs IGN] phase [Termes descripteurs IGN] plan de masse [Termes descripteurs IGN] qualité des données [Termes descripteurs IGN] récepteur GNSS [Termes descripteurs IGN] récepteur monofréquence [Termes descripteurs IGN] réflecteur [Termes descripteurs IGN] source d'erreur [Termes descripteurs IGN] trajet multiple Résumé : (auteur) The investigations on low-cost single frequency GNSS receivers at the Institute of Engineering Geodesy (IIGS) show that u-blox GNSS receivers combined with low-cost antennas and self-constructed L1-optimized choke rings can reach an accuracy which almost meets the requirements of geodetic applications (see Zhang and Schwieger [25]). However, the quality (accuracy and reliability) of low-cost GNSS receiver data should still be improved, particularly in environments with obstructions. The multipath effects are a major error source for the short baselines. The ground plate or the choke ring ground plane can reduce the multipath signals from the horizontal reflector (e. g. ground). However, the shieldings cannot reduce the multipath signals from the vertical reflectors (e. g. walls). Because multipath effects are spatially and temporally correlated, an algorithm is developed for reducing the multipath effect by considering the spatial correlations of the adjoined stations (see Zhang and Schwieger [24]). In this paper, an algorithm based on the temporal correlations will be introduced. The developed algorithm is based on the periodic behavior of the estimated coordinates and not on carrier phase raw data, which is easy to use. Because, for the users, coordinates are more accessible than the raw data. The multipath effect can cause periodic oscillations but the periods change over time. Besides this, the multipath effect’s influence on the coordinates is a mixture of different multipath signals from different satellites and different reflectors. These two properties will be used to reduce the multipath effect. The algorithm runs in two steps and iteratively. Test measurements were carried out in a multipath intensive environment; the accuracies of the measurements are improved by about 50 % and the results can be delivered in near-real-time (in ca. 30 minutes), therefore the algorithm is suitable for structural health monitoring applications. Numéro de notice : A2020-217 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1515/jag-2019-0059 date de publication en ligne : 27/03/2020 En ligne : https://doi.org/10.1515/jag-2019-0059 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94910 [article]

Wavelet-adaptive neural subtractive clustering fuzzy inference system to enhance low-cost and high-speed INS/GPS navigation system / Elahe S. Abdolkarimi in GPS solutions, vol 24 n° 2 (April 2020)  

Public [article]  inGPS solutions > vol 24 n° 2 (April 2020) Titre : Wavelet-adaptive neural subtractive clustering fuzzy inference system to enhance low-cost and high-speed INS/GPS navigation system Type de document : Article/Communication Auteurs : Elahe S. Abdolkarimi, Auteur ; Mohammad-Reza Mosavi, Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] centrale inertielle [Termes descripteurs IGN] coût [Termes descripteurs IGN] filtre de Kalman [Termes descripteurs IGN] GPS-INS [Termes descripteurs IGN] imprécision des données [Termes descripteurs IGN] incertitude des données [Termes descripteurs IGN] Inférence floue [Termes descripteurs IGN] précision du positionnement [Termes descripteurs IGN] rapport signal sur bruit [Termes descripteurs IGN] transformation en ondelettes [Termes descripteurs IGN] vitesse de déplacement Résumé : (auteur) The combined navigation system consisting of Global Positioning System (GPS) and Inertial Navigation System in a complementary mode assures an accurate, reliable, and continuous positioning capability in the navigation system. Because of problems such as dealing with a low-cost MEMS-based inertial sensors having a high level of uncertainty and imprecision, stochastic noise, a high-speed vehicle, high noisy real data, and long-term GPS signal outage during the real-time flight test, the advantage is taken for some approaches in different steps: (1) utilizing discrete wavelet transform technique to enhance the signal-to-noise ratio in raw and noisy inertial sensor signals and attenuate high-frequency noise as a preprocessing phase to prepare more accurate data for the proposed model and (2) employing adaptive neural subtractive clustering fuzzy inference system (ANSCFIS) which combines and extracts the best feature of adaptive neuro-fuzzy inference system (ANFIS), and the subtractive clustering algorithm with fewer rules than the ANFIS method, aiming to improve a more efficient, accurate, and especially a faster method which enhances the prediction accuracy and speeds up the positioning system. The achieved accuracies for the proposed model are discussed and compared with the extended Kalman filter (EKF), ANFIS, and ANSCFIS which are implemented and tested experimentally using a high-speed vehicle in three GPS blockages. The proposed model shows considerable improvements in high-speed navigation using low-cost MEMS-based inertial sensors in case of long-term GPS blockage. Numéro de notice : A2020-084 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10291-020-0951-y date de publication en ligne : 11/01/2020 En ligne : https://doi.org/10.1007/s10291-020-0951-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94654 [article]

Learning and adapting robust features for satellite image segmentation on heterogeneous data sets / Sina Ghassemi in IEEE Transactions on geoscience and remote sensing, vol 57 n° 9 (September 2019)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 57 n° 9 (September 2019) . - pp 6517 - 6529 Titre : Learning and adapting robust features for satellite image segmentation on heterogeneous data sets Type de document : Article/Communication Auteurs : Sina Ghassemi, Auteur ; Attilio Friandrotti, Auteur ; Gianluca Francini, Auteur ; Enrico Magli, Auteur Année de publication : 2019 Article en page(s) : pp 6517 - 6529 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes descripteurs IGN] apprentissage profond [Termes descripteurs IGN] chaîne de traitement [Termes descripteurs IGN] classification par réseau neuronal convolutif [Termes descripteurs IGN] coût [Termes descripteurs IGN] données hétérogènes [Termes descripteurs IGN] image satellite [Termes descripteurs IGN] méthode robuste [Termes descripteurs IGN] réseau neuronal convolutif [Termes descripteurs IGN] segmentation d'image [Termes descripteurs IGN] test de performance Résumé : (auteur) This paper addresses the problem of training a deep neural network for satellite image segmentation so that it can be deployed over images whose statistics differ from those used for training. For example, in postdisaster damage assessment, the tight time constraints make it impractical to train a network from scratch for each image to be segmented. We propose a convolutional encoder–decoder network able to learn visual representations of increasing semantic level as its depth increases, allowing it to generalize over a wider range of satellite images. Then, we propose two additional methods to improve the network performance over each specific image to be segmented. First, we observe that updating the batch normalization layers’ statistics over the target image improves the network performance without human intervention. Second, we show that refining a trained network over a few samples of the image boosts the network performance with minimal human intervention. We evaluate our architecture over three data sets of satellite images, showing the state-of-the-art performance in binary segmentation of previously unseen images and competitive performance with respect to more complex techniques in a multiclass segmentation task. Numéro de notice : A2019-341 Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2019.2906689 date de publication en ligne : 17/04/2019 En ligne : https://doi.org/10.1109/TGRS.2019.2906689 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93379 [article]

Spatial mining of migration patterns from web demographics / T. Edwin Chow in International journal of geographical information science IJGIS, vol 32 n° 9-10 (September - October 2018)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 32 n° 9-10 (September - October 2018) . - pp 1977 - 1998 Titre : Spatial mining of migration patterns from web demographics Type de document : Article/Communication Auteurs : T. Edwin Chow, Auteur ; Ryan T. Schuermann, Auteur ; Anne H. Ngu, Auteur ; Khila R. Dahal, Auteur Année de publication : 2018 Article en page(s) : pp 1977 - 1998 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes descripteurs IGN] analyse multiéchelle [Termes descripteurs IGN] arbre de décision [Termes descripteurs IGN] coût [Termes descripteurs IGN] données démographiques [Termes descripteurs IGN] exploration de données géographiques [Termes descripteurs IGN] migration humaine [Termes descripteurs IGN] qualité des données [Termes descripteurs IGN] Texas (Etats-Unis) [Termes descripteurs IGN] Viet Nam Résumé : (Auteur) Volunteered Geographic Information, social media, and data from Information and Communication Technology are emerging sources of big data that contribute to the development and understanding of the spatiotemporal distribution of human population. However, the inherent anonymity of these crowd-sourced or crowd-harvested data sources lack the socioeconomic and demographic attributes to examine and explain human mobility and spatiotemporal patterns. In this paper, we investigate an Internet-based demographic data source, personal microdata databases publicly accessible on the World Wide Web (hereafter web demographics), as potential sources of aspatial and spatiotemporal information regarding the landscape of human dynamics. The objectives of this paper are twofold: (1) to develop an analytical framework to identify mobile population from web demographics as an individual-level residential history data, and (2) to explore their geographic and demographic patterns of migration. Using web demographics of Vietnamese–Americans in Texas collected in 2010 as a case study, this paper (1) addresses entity resolution and identifies mobile population through the application of a Cost-Sensitive Alternative Decision Tree (CS-ADT) algorithm, (2) investigates migration pathways and clusters to include both short- and long-distance patterns, and (3) analyze the demographic characteristics of mobile population and the functional relationship with travel distance. By linking the physical space at the individual level, this unique methodology attempts to enhance the understanding of human movement at multiple spatial scales. Numéro de notice : A2018-309 Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2018.1470633 date de publication en ligne : 08/05/2018 En ligne : https://doi.org/10.1080/13658816.2018.1470633 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90466 [article]

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The use of low-cost, single-frequency GNSS receivers in mapping surveys / M. Tsakiri in Survey review, vol 50 n° 358 (January 2018)  

Public [article]  inSurvey review > vol 50 n° 358 (January 2018) . - pp 46 - 56 Titre : The use of low-cost, single-frequency GNSS receivers in mapping surveys Type de document : Article/Communication Auteurs : M. Tsakiri, Auteur ; A. Sioulis, Auteur ; George Piniotis, Auteur Année de publication : 2018 Article en page(s) : pp 46 - 56 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] coût [Termes descripteurs IGN] Grèce [Termes descripteurs IGN] positionnement cinématique en temps réel [Termes descripteurs IGN] récepteur GNSS [Termes descripteurs IGN] récepteur monofréquence [Termes descripteurs IGN] test de performance Résumé : (auteur) The emergence of low-cost, navigation-type receivers capable to provide carrier-phase data (the so-called high-sensitivity carrier-phase positioning) has been steadily growing over the recent years. The aim of this study was to evaluate the positioning performance of a high-sensitivity receiver in a network real-time kinematic environment for mapping surveying applications. Specifically, using as rover receiver the u-blox NEO-7P module and the low-cost antenna Tallysman TW2410, sets of data were collected for the purpose of mapping surveying. The external accuracy of the obtained solutions is considered using different positioning techniques and the internal indicators of the system during real-time kinematic (RTK) positioning are assessed. The assessment indicates that in benign environments this type of receivers produce results that are comparable to RTK positioning using geodetic receivers and with a significantly lower cost. Numéro de notice : A2018-177 Thématique : POSITIONNEMENT Nature : Article DOI : 10.1080/00396265.2016.1222344 date de publication en ligne : 16/09/2016 En ligne : https://doi.org/10.1080/00396265.2016.1222344 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89821 [article]

Economics of mapping using small manned and unmanned aerial vehicles / Orrin H. Thomas in Photogrammetric Engineering & Remote Sensing, PERS, vol 83 n° 8 (August 2017)  

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The cost(s) of geospatial open data / Peter A. Johnson in Transactions in GIS, vol 21 n° 3 (June 2017)  

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Assessing the ecosystem service flood protection of a riparian forest by applying a cascade approach / Nina-Christin Barth in Ecosystem Services, vol 21 Part A (October 2016)  

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Mobilités à la loupe / Françoise de Blomac in DécryptaGéo le mag, n° 179 (septembre 2016)

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Open access: at what cost ? / Rebecca Pool in Research information, n° 85 (August - September 2016) 

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Belastungen der deutschen Forstwirtschaft aus der Schutz- und Erholungsfunktion des Waldes / Markus Dög in Landbauforschung, vol 66 n° 2 (06-2016) 

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Estimations dendrométriques pour l’aménagement forestier à l’aide de LiDAR aéroporté : premier démonstrateur en forêts littorales dunaires / Alain Munoz in Rendez-vous techniques, n° 50 (Hiver 2016) 

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Improving the quality of low-cost GPS receiver data for monitoring using spatial correlations / Li Zhang in Journal of applied geodesy, vol 10 n° 2 (June 2016)  

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Optimization of observation plan based on the stochastic characteristics of the geodetic network / Wojciech Pachelski in Reports on geodesy and geoinformatics, vol 101 (June 2016)  

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Land cover dynamics monitoring with Landsat data in Kunming, China: a cost-effective sampling and modelling scheme using Google Earth imagery and random forests / Ning Lu in Geocarto international, vol 30 n° 1 - 2 (January - February 2015)

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