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Characteristics of the BDS-3 multipath effect and mitigation methods using precise point positioning / Ran Lu in GPS solutions, vol 26 n° 2 (April 2022)
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Titre : Characteristics of the BDS-3 multipath effect and mitigation methods using precise point positioning Type de document : Article/Communication Auteurs : Ran Lu, Auteur ; Wen Chen, Auteur ; Chenglong Zhang, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 41 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] constellation BeiDou
[Termes IGN] correction du trajet multiple
[Termes IGN] modèle stochastique
[Termes IGN] orbite géostationnaire
[Termes IGN] orbite terrestre
[Termes IGN] positionnement par BeiDou
[Termes IGN] positionnement ponctuel précis
[Termes IGN] répétabilité
[Termes IGN] trajet multipleRésumé : (auteur) Multipath effect is one of the main challenges of precise point positioning (PPP) in complex environments. Nowadays, the BeiDou global navigation satellite system (BDS-3) constellation was fully operational. We evaluated the multipath characteristics of BDS-3 open-service signals. The results indicate that the B2a signal had the best anti-multipath performance, and B1C signal had the worst capability. Since BDS-3 satellites with different orbital types have different orbital repeat time, the traditional method based on multipath time-domain repeatability is complicated to alleviate the multipath error on BDS-3 satellites. In contrast, the multipath spatial-domain repeatability method does not need to calculate the orbital repeat times and is only related to the position of the satellite in the sky. It has the advantages of simple algorithm and easy implementation. We selected a multipath hemispherical map (MHM) and a MHM based on trend-surface analysis (T-MHM) to evaluate the effects of BDS-3 PPP multipath correction. The positioning results for the inclined geosynchronous orbit (IGSO) and medium earth orbit (MEO) satellites, which were separately modeled and corrected, are slightly better than those obtained when they were modeled and corrected together. Compared with the uncorrected multipath, the positioning accuracy of B1I/B3I and B1C/B2a ionospheric-free (IF) combinations using the MHM can be improved by 52.7% and 51.6% and the convergence time can be shortened by 48.6% and 57.5%, respectively. The positioning accuracy of B1I/B3I and B1C/B2a IF combinations using the T-MHM can be improved by 67% and 66.9% and the convergence time can be shortened by 69.3% and 76.5%, respectively. The T-MHM introduces trend-surface analysis to model the spatial variation of the multipath inside the grid, which effectively alleviates high-frequency and low-frequency multipath. This study is of great significance for further improvements to the application of BDS-3 in complex environments. Numéro de notice : A2022-106 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01227-1 Date de publication en ligne : 24/01/2022 En ligne : https://doi.org/10.1007/s10291-022-01227-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99606
in GPS solutions > vol 26 n° 2 (April 2022) . - n° 41[article]Detecting individuals' spatial familiarity with urban environments using eye movement data / Hua Liao in Computers, Environment and Urban Systems, vol 93 (April 2022)
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Titre : Detecting individuals' spatial familiarity with urban environments using eye movement data Type de document : Article/Communication Auteurs : Hua Liao, Auteur ; Wendi Zhao, Auteur ; Changbo Zhang, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 101758 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse visuelle
[Termes IGN] apprentissage automatique
[Termes IGN] classification par forêts d'arbres décisionnels
[Termes IGN] navigation pédestre
[Termes IGN] oculométrie
[Termes IGN] service fondé sur la position
[Termes IGN] zone urbaine
[Vedettes matières IGN] GéovisualisationRésumé : (auteur) The spatial familiarity of environments is an important high-level user context for location-based services (LBS). Knowing users' familiarity level of environments is helpful for enabling context-aware LBS that can automatically adapt information services according to users' familiarity with the environment. Unlike state-of-the-art studies that used questionnaires, sketch maps, mobile phone positioning (GPS) data, and social media data to measure spatial familiarity, this study explored the potential of a new type of sensory data - eye movement data - to infer users' spatial familiarity of environments using a machine learning approach. We collected 38 participants' eye movement data when they were performing map-based navigation tasks in familiar and unfamiliar urban environments. We trained and cross-validated a random forest classifier to infer whether the users were familiar or unfamiliar with the environments (i.e., binary classification). By combining basic statistical features and fixation semantic features, we achieved a best accuracy of 81% in a 10-fold classification and 70% in the leave-one-task-out (LOTO) classification. We found that the pupil diameter, fixation dispersion, saccade duration, fixation count and duration on the map were the most important features for detecting users' spatial familiarity. Our results indicate that detecting users' spatial familiarity from eye tracking data is feasible in map-based navigation and only a few seconds (e.g., 5 s) of eye movement data is sufficient for such detection. These results could be used to develop context-aware LBS that adapt their services to users' familiarity with the environments. Numéro de notice : A2022-121 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1016/j.compenvurbsys.2022.101758 Date de publication en ligne : 21/01/2022 En ligne : https://doi.org/10.1016/j.compenvurbsys.2022.101758 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99663
in Computers, Environment and Urban Systems > vol 93 (April 2022) . - n° 101758[article]Detection and mitigation of GNSS spoofing via the pseudorange difference between epochs in a multicorrelator receiver / Xiangyong Shang in GPS solutions, vol 26 n° 2 (April 2022)
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Titre : Detection and mitigation of GNSS spoofing via the pseudorange difference between epochs in a multicorrelator receiver Type de document : Article/Communication Auteurs : Xiangyong Shang, Auteur ; Fuping Sun, Auteur ; Lundong Zhang, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 37 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] anti-leurrage
[Termes IGN] atténuation du signal
[Termes IGN] brouillage
[Termes IGN] détection de leurrage
[Termes IGN] détection du signal
[Termes IGN] filtre de Kalman
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] qualité du signal
[Termes IGN] récepteur GNSS
[Termes IGN] signal GNSSRésumé : (auteur) Spoofing attacks have become an increasing threat to global navigation satellite system receivers. Existing anti-spoofing algorithms concentrate on the detection of these attacks; however, they are unable to prevent the counterfeit signal, which causes false position and timing results. Some defense techniques require the assistance of other sensors or measurement devices located at different positions. These impose many restrictions on the practical applications of anti-spoofing algorithms. In this study, the multicorrelator estimator, designed initially to prevent multipath signals, is applied to detect and mitigate spoofing. A statistic is proposed for spoofing detection based on the code phase difference between counterfeit and authentic signals. This statistic can significantly reduce the rate of false and missed alarms. Assuming there is no spoofing at the beginning, the pseudorange difference between epochs is derived for spoofing validation, allowing spoofing suppression in a single receiver. Based on this study, an estimation-validation-mitigation structure is presented. A robust extended Kalman filter is proposed to reduce gross errors in the multicorrelator measurements and improve estimation accuracy. Public-spoofing datasets recorded in real environments were used to verify the performance of different parameters. A total of 81 complex correlators were introduced in the experiments. Results show that using the proposed scheme, the position or time offsets caused by spoofing drop from 600 m to approximately 20 m, and the spoofing is mitigated considerably. The proposed method provides an effective anti-spoofing structure that requires only a single antenna and does not require additional sensors. Numéro de notice : A2022-108 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-022-01224-4 Date de publication en ligne : 16/01/2022 En ligne : https://doi.org/10.1007/s10291-022-01224-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99610
in GPS solutions > vol 26 n° 2 (April 2022) . - n° 37[article]Direct photogrammetry with multispectral imagery for UAV-based snow depth estimation / Kathrin Maier in ISPRS Journal of photogrammetry and remote sensing, vol 186 (April 2022)
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Titre : Direct photogrammetry with multispectral imagery for UAV-based snow depth estimation Type de document : Article/Communication Auteurs : Kathrin Maier, Auteur ; Andrea Nascetti, Auteur ; Ward van Pelt, Auteur ; Gunhild Rosqvist, Auteur Année de publication : 2022 Article en page(s) : pp 1 - 18 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] analyse en composantes principales
[Termes IGN] bande infrarouge
[Termes IGN] épaisseur
[Termes IGN] erreur moyenne quadratique
[Termes IGN] géoréférencement direct
[Termes IGN] image captée par drone
[Termes IGN] image multibande
[Termes IGN] manteau neigeux
[Termes IGN] modèle numérique de surface
[Termes IGN] photogrammétrie aérienne
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] qualité du modèle
[Termes IGN] reconstruction 3D
[Termes IGN] structure-from-motion
[Termes IGN] SuèdeRésumé : (Auteur) More accurate snow quality predictions are needed to economically and socially support communities in a changing Arctic environment. This contrasts with the current availability of affordable and efficient snow monitoring methods. In this study, a novel approach is presented to determine spatial snow depth distribution in challenging alpine terrain that was tested during a field campaign performed in the Tarfala valley, Kebnekaise mountains, northern Sweden, in April 2019. The combination of a multispectral camera and an Unmanned Aerial Vehicle (UAV) was used to derive three-dimensional (3D) snow surface models via Structure from Motion (SfM) with direct georeferencing. The main advantage over conventional photogrammetric surveys is the utilization of accurate Real-Time Kinematic (RTK) positioning which enables direct georeferencing of the images, and therefore eliminates the need for ground control points. The proposed method is capable of producing high-resolution 3D snow-covered surface models (7 cm/pixel) of alpine areas up to eight hectares in a fast, reliable and affordable way. The test sites’ average snow depth was 160 cm with an average standard deviation of 78 cm. The overall Root-Mean-Square Errors (RMSE) of the snow depth range from 11.52 cm for data acquired in ideal surveying conditions to 41.03 cm in aggravated light and wind conditions. Results of this study suggest that the red components in the electromagnetic spectrum, i.e., the red, red edge, and near-infrared (NIR) band, contain the majority of information used in photogrammetric processing. The experiments highlighted a significant influence of the multi-spectral imagery on the quality of the final snow depth estimation as well as a strong potential to reduce processing times and computational resources by limiting the dimensionality of the imagery through the application of a Principal Component Analysis (PCA) before the photogrammetric 3D reconstruction. The proposed method is part of closing the scale gap between discrete point measurements and regional-scale remote sensing and complements large-scale remote sensing data and snow model output with an adequate validation source. Numéro de notice : A2022-066 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2022.01.020 Date de publication en ligne : 09/02/2022 En ligne : https://doi.org/10.1016/j.isprsjprs.2022.01.020 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99783
in ISPRS Journal of photogrammetry and remote sensing > vol 186 (April 2022) . - pp 1 - 18[article]Exemplaires(3)
Code-barres Cote Support Localisation Section Disponibilité 081-2022041 SL Revue Centre de documentation Revues en salle Disponible 081-2022043 DEP-RECP Revue LASTIG Dépôt en unité Exclu du prêt 081-2022042 DEP-RECF Revue Nancy Dépôt en unité Exclu du prêt Hybrid georeferencing of images and LiDAR data for UAV-based point cloud collection at millimetre accuracy / Norbert Haala in ISPRS Open Journal of Photogrammetry and Remote Sensing, vol 4 (April 2022)
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Titre : Hybrid georeferencing of images and LiDAR data for UAV-based point cloud collection at millimetre accuracy Type de document : Article/Communication Auteurs : Norbert Haala, Auteur ; Michael Kölle, Auteur ; Michael Cramer, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 100014 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] aérotriangulation automatisée
[Termes IGN] appariement d'images
[Termes IGN] collecte de données
[Termes IGN] compensation par faisceaux
[Termes IGN] données lidar
[Termes IGN] géoréférencement direct
[Termes IGN] image captée par drone
[Termes IGN] orthoimage
[Termes IGN] précision millimétrique
[Termes IGN] semis de points
[Termes IGN] zone d'intérêtRésumé : (auteur) During the last two decades, UAV emerged as standard platform for photogrammetric data collection. Main motivation in that early phase was the cost effective airborne image collection at areas of limited size. This was already feasible by rather simple payloads like an off-the-shelf, compact camera and a navigation-grade GNSS sensor. Meanwhile, dedicated sensor systems enable applications that have not been feasible in the past. One example is the airborne collection of dense 3D point clouds at millimetre accuracies, which will be discussed in our paper. For this purpose, we collect both LiDAR and image data from a joint UAV platform and apply a so-called hybrid georeferencing. This process integrates photogrammetric bundle block adjustment with direct georeferencing of LiDAR point clouds. By these means georeferencing accuracy is improved for the LiDAR point cloud by an order of magnitude. We demonstrate the feasibility of our approach in the context of a project, which aims on monitoring of subsidence of about 10 mm/year. The respective area of interest is defined by a ship lock and its vicinity of mixed use. In that area, multiple UAV flights were captured and evaluated for a period of three years. As our main contribution, we demonstrate that 3D point accuracies at sub-centimetre level can be achieved. This is realized by joint orientation of laser scans and images in a hybrid adjustment framework, which enables accuracies corresponding to the GSD of the captured imagery. Numéro de notice : A2022-236 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1016/j.ophoto.2022.100014Get rights and content Date de publication en ligne : 16/03/2022 En ligne : https://doi.org/10.1016/j.ophoto.2022.100014Get rights and content Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100146
in ISPRS Open Journal of Photogrammetry and Remote Sensing > vol 4 (April 2022) . - n° 100014[article]Improving the (re-)convergence of multi-GNSS real-time precise point positioning through regional between-satellite single-differenced ionospheric augmentation / Ahao Wang in GPS solutions, vol 26 n° 2 (April 2022)
PermalinkMining crowdsourced trajectory and geo-tagged data for spatial-semantic road map construction / Jincai Huang in Transactions in GIS, vol 26 n° 2 (April 2022)
PermalinkOn enhanced PPP with single difference between-satellite ionospheric constraints / Yan Xiang in Navigation : journal of the Institute of navigation, vol 69 n° 1 (Spring 2022)
PermalinkRegularized integer least-squares estimation: Tikhonov’s regularization in a weak GNSS model / Zemin Wu in Journal of geodesy, vol 96 n° 4 (April 2022)
PermalinkResearch on machine intelligent perception of urban geographic location based on high resolution remote sensing images / Jun Chen in Photogrammetric Engineering & Remote Sensing, PERS, vol 88 n° 4 (April 2022)
PermalinkResults on GNSS spoofing mitigation using multiple receivers / Niklas Stenberg in Navigation : journal of the Institute of navigation, vol 69 n° 1 (Spring 2022)
PermalinkValidating the impact of various ionosphere correction on mid to long baselines and point positioning using GPS dual-frequency receivers / Alaa A. Elghazouly in Journal of applied geodesy, vol 16 n° 2 (April 2022)
PermalinkVolunteered geographic information mobile application for participatory landslide inventory mapping / Raden Muhammad Anshori in Computers & geosciences, vol 161 (April 2022)
PermalinkAssessing ZWD models in delay and height domains using data from stations in different climate regions / Thainara Munhoz Alexandre de Lima in Applied geomatics, vol 14 n° 1 (March 2022)
PermalinkCartographie et caractérisation des lieux d'intérêt de cervidés en milieu forestier / Laurence Jolivet in Cartes & Géomatique, n° 247-248 (mars-juin 2022)
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