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GNSS integer ambiguity posterior probability calculation with controllable accuracy / Zemin Wu in Journal of geodesy, vol 96 n° 8 (August 2022)  

Public [article]  inJournal of geodesy > vol 96 n° 8 (August 2022) . - n° 53 Titre : GNSS integer ambiguity posterior probability calculation with controllable accuracy Type de document : Article/Communication Auteurs : Zemin Wu, Auteur Année de publication : 2022 Article en page(s) : n° 53 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] ambiguïté entière [Termes IGN] erreur moyenne quadratique [Termes IGN] estimation de précision [Termes IGN] incertitude de position [Termes IGN] positionnement par GNSS [Termes IGN] résolution d'ambiguïté Résumé : (auteur) Integer ambiguity resolution (IAR) is one of the key techniques in GNSS high precise positioning. However, an overlooked incorrect integer ambiguity solution may cause severe biases in the positioning results. The optimal integer aperture estimator (IAE) has the largest possible success rate given a certain fail rate. An alternative approach that take advantage of ambiguity integer nature to minimize the solution’s mean squared error (MSE) is known as the best integer equivariant (BIE) estimator. Both of which are associated with the posterior probability of the GNSS integer ambiguity. It is therefore of great significance to calculate posterior probability precisely and efficiently. Due to the occurrence of infinite sums, practical calculation approaches approximate the exact value by neglecting sufficiently small terms in the sum. As a result, they can only produce posterior probability calculation result, information about the result’s accuracy cannot be produced. In this contribution, the value of the posterior probability is bounded from below and from above by dividing the infinite sum into two parts: the major finite part and the minor infinite part. They are calculated partly by enumeration and partly by algebraical bounding. The obtained upper and lower bounds are rigorous and in closed form, so that can be conveniently used. Based on both of the bounds, a method of posterior probability calculation with controllable accuracy is proposed. It not only produces posterior probability calculation result, but also calculation error, which is always smaller than the user-defined acceptable error. Numerical experiments have verified that the proposed approach has advantages on both controllable calculation accuracy and adjustable computational workload. Numéro de notice : A2022-607 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-022-01633-w Date de publication en ligne : 10/08/2022 En ligne : https://doi.org/10.1007/s00190-022-01633-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101386 [article]

A new method for evaluation of the positional error of low-cost devices based on GNSS integrity for transportation applications / Luciano Aparecido Barbosa in Boletim de Ciências Geodésicas, vol 28 n° 1 ([01/03/2022])  

Public [article]  inBoletim de Ciências Geodésicas > vol 28 n° 1 [01/03/2022] Titre : A new method for evaluation of the positional error of low-cost devices based on GNSS integrity for transportation applications Type de document : Article/Communication Auteurs : Luciano Aparecido Barbosa, Auteur ; Henrique Cândido de Oliveira, Auteur ; Wagner Carrupt Machado, Auteur ; Diogenes Cortijo Costa, Auteur Année de publication : 2022 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie [Termes IGN] erreur de positionnement [Termes IGN] estimation de précision [Termes IGN] milieu urbain [Termes IGN] positionnement cinématique [Termes IGN] récepteur GPS Résumé : (auteur) GNSS integrity assessment has always been linked to the need for reliable positional information. Initially used in aviation, positional information gained even more relevance in terrestrial applications with the popularity of GNSS. However, the terrestrial environment has many influences over GNSS signals, which reduces the positional quality of tracking objects. Advances have been achieved in the use of integrity monitoring algorithms, but there are limitations to their use, especially those concerning positional accuracy in urban environments with low-cost devices. This paper aims to discuss a comparative method using two low-cost GNSS receivers designed for transportation applications and to verify whether this method can evaluate positional quality in pre-established locations, as well as the possibilities of using these devices for transportation applications, considering the positional error. Results show that, in the static experiment, the receiver assembled with a GPS antenna active embedded was more accurate than the receiver assembled with an external antenna, presenting better values in 5 out of 10 evaluated sites, while the external antenna performed better in only 2 sites. However, in a kinematic evaluation, the receiver assembled with an external antenna provided better results when considering positional error as assessment criterion, resulting in values less than or equal to 8 meters in 99.7% of the route evaluated, while the embedded antenna had 95.3%. Numéro de notice : A2022-683 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : sans En ligne : https://revistas.ufpr.br/bcg/article/download/85448/46218 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101547 [article]

Digital terrain models generated with low-cost UAV photogrammetry: Methodology and accuracy / Sergio Jiménez-Jiménez in ISPRS International journal of geo-information, vol 10 n° 5 (May 2021)  

Public [article]  inISPRS International journal of geo-information > vol 10 n° 5 (May 2021) . - n° 285 Titre : Digital terrain models generated with low-cost UAV photogrammetry: Methodology and accuracy Type de document : Article/Communication Auteurs : Sergio Jiménez-Jiménez, Auteur ; Waldo Ojeda-Bustamante, Auteur ; Mariana de Jesús Marcial, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 285 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] capteur aérien [Termes IGN] estimation de précision [Termes IGN] étalonnage d'instrument [Termes IGN] géomorphologie [Termes IGN] image captée par drone [Termes IGN] modèle numérique de terrain [Termes IGN] modélisation géométrique de prise de vue [Termes IGN] photogrammétrie aérienne [Termes IGN] plan de vol [Termes IGN] point d'appui [Termes IGN] précision des mesures [Termes IGN] qualité des données [Termes IGN] semis de points [Termes IGN] structure-from-motion Résumé : (auteur) Digital terrain model (DTM) generation is essential to recreating terrain morphology once the external elements are removed. Traditional survey methods are still used to collect accurate geographic data on the land surface. Given the emergence of unmanned aerial vehicles (UAVs) equipped with low-cost digital cameras and better photogrammetric methods for digital mapping, efficient approaches are necessary to allow rapid land surveys with high accuracy. This paper provides a review, complemented with the authors’ experience, regarding the UAV photogrammetric process and field survey parameters for DTM generation using popular commercial photogrammetric software to process images obtained with fixed-wing or multicopter UAVs. We analyzed the quality and accuracy of the DTMs based on four categories: (i) the UAV system (UAV platforms and camera); (ii) flight planning and image acquisition (flight altitude, image overlap, UAV speed, orientation of the flight line, camera configuration, and georeferencing); (iii) photogrammetric DTM generation (software, image alignment, dense point cloud generation, and ground filtering); (iv) geomorphology and land use/cover. For flat terrain, UAV photogrammetry provided a horizontal root mean square error (RMSE) between 1 to 3 × the ground sample distance (GSD) and a vertical RMSE between 1 to 4.5 × GSD, and, for complex topography, a horizontal RMSE between 1 to 7 × GSD and a vertical RMSE between 1.5 to 5 × GSD. Finally, we stress that UAV photogrammetry can provide DTMs with high accuracy when the photogrammetric process variables are optimized. Numéro de notice : A2021-394 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.3390/ijgi10050285 Date de publication en ligne : 29/04/2021 En ligne : https://doi.org/10.3390/ijgi10050285 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97680 [article]

OpenStreetMap quality assessment using unsupervised machine learning methods / Kent T. Jacobs in Transactions in GIS, Vol 24 n° 5 (October 2020)  

Public [article]  inTransactions in GIS > Vol 24 n° 5 (October 2020) . - pp 1280-1298 Titre : OpenStreetMap quality assessment using unsupervised machine learning methods Type de document : Article/Communication Auteurs : Kent T. Jacobs, Auteur ; Scott W. Mitchell, Auteur Année de publication : 2020 Article en page(s) : pp 1280-1298 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web [Termes IGN] analyse comparative [Termes IGN] apprentissage automatique [Termes IGN] apprentissage non-dirigé [Termes IGN] approche participative [Termes IGN] Canada [Termes IGN] données localisées des bénévoles [Termes IGN] estimation de précision [Termes IGN] fiabilité des données [Termes IGN] OpenStreetMap [Termes IGN] Ottawa [Termes IGN] qualité des données Résumé : (Auteur) The reliability and quality of volunteered geographic information (VGI) continue to be pressing concerns. Many VGI projects lack standard geospatial data quality assurance procedures, and the reliability of contributors remains in question. Traditional approaches rely on comparing VGI to an “authoritative” or “gold standard” dataset to assess quality. This study investigates VGI quality by analysing the OpenStreetMap (OSM) database in Ottawa‐Gatineau, focusing on historical map features and contributor data to gain an understanding of how users are contributing to the database, and their ability to do so accurately. Unsupervised machine learning analyses expose a cluster of experienced contributors classified as “OSM validators/experts”, which are then further used to attribute data quality. They are identified through a combination of strong contribution loadings associated with the use and experience of advanced OSM editors, and weaker loadings associated with feature creation and frequency of contributions leading to further correction. Limitations are discussed with implications for future work. Numéro de notice : A2020-701 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12680 Date de publication en ligne : 18/08/2020 En ligne : https://doi.org/10.1111/tgis.12680 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96224 [article]

Rethinking error estimations in geospatial data: the correct way to determine product accuracy / Qassim Abdullah in Photogrammetric Engineering & Remote Sensing, PERS, vol 86 n° 7 (July 2020)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 86 n° 7 (July 2020) . - pp 397-403 Titre : Rethinking error estimations in geospatial data: the correct way to determine product accuracy Type de document : Article/Communication Auteurs : Qassim Abdullah, Auteur Année de publication : 2020 Article en page(s) : pp 397-403 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie moderne [Termes IGN] cartographie numérique [Termes IGN] détection d'erreur [Termes IGN] données localisées [Termes IGN] ellipsoïde (géodésie) [Termes IGN] estimation de précision [Termes IGN] nivellement direct [Termes IGN] point d'appui [Termes IGN] réalité de terrain [Termes IGN] système de référence géodésique [Termes IGN] système de référence local Résumé : (Auteur) Numéro de notice : A2020-380 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.14358/PERS.86.7.397 Date de publication en ligne : 01/07/2020 En ligne : https://doi.org/10.14358/PERS.86.7.397 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95425 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
105-2020071	SL	Revue	Centre de documentation	Revues en salle	Disponible

Improved wavelet neural network based on change rate to predict satellite clock bias / Xu Wang in Survey review, vol 52 n° 372 (May 2020)  

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Use of automated change detection and VGI sources for identifying and validating urban land use change / Ana-Maria Olteanu-Raimond in Remote sensing, vol 12 n° 7 (April 2020)  

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Assessing the shape accuracy of coarse resolution burned area identifications / Michael L. Humber in IEEE Transactions on geoscience and remote sensing, vol 58 n° 3 (March 2020)  

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Assessment of dense image matchers for digital surface model generation using airborne and spaceborne images – an update / Yilong Han in Photogrammetric record, vol 35 n° 169 (March 2020)  

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Estimating wheat yields in Australia using climate records, satellite image time series and machine learning methods / Elisa Kamir in ISPRS Journal of photogrammetry and remote sensing, vol 160 (February 2020)  

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Accuracy assessment of relative and precise point positioning online GPS processing services / Ahmed El Shouny in Journal of applied geodesy, vol 13 n° 3 (July 2019)  

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In-situ measurements from mobile platforms: An emerging approach to address the old challenges associated with forest inventories / Xinlian Liang in ISPRS Journal of photogrammetry and remote sensing, vol 143 (September 2018)  

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Exploring geo-tagged photos for land cover validation with deep learning / Hanfa Xing in ISPRS Journal of photogrammetry and remote sensing, vol 141 (July 2018)  

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A review of accuracy assesment for object-based image analysis: from per pixel to per-polygon approaches [review article] / Su Ye in ISPRS Journal of photogrammetry and remote sensing, vol 141 (July 2018)  

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Pré-estimation et analyse de la précision pour la cartographie par drone / Laurent Valentin Jospin in XYZ, n° 155 (juin - août 2018)

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