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Technical considerations for modernizing Nova Scotia’s Coordinate Referencing System / Jason Bond in Geomatica, vol 70 n° 2 (June 2016)  

Public [article]  inGeomatica > vol 70 n° 2 (June 2016) . - pp 85 - 96 Titre : Technical considerations for modernizing Nova Scotia’s Coordinate Referencing System Type de document : Article/Communication Auteurs : Jason Bond, Auteur Année de publication : 2016 Article en page(s) : pp 85 - 96 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] Canada [Termes IGN] coordonnées géodésiques [Termes IGN] densification géodésique [Termes IGN] Nouvelle-Ecosse (Canada) [Termes IGN] précision centimétrique [Termes IGN] station de contrôle [Termes IGN] système de coordonnées [Termes IGN] système de référence géodésique [Termes IGN] système de référence local [Termes IGN] temps réel Résumé : (auteur) The Nova Scotia Coordinate Referencing System (NSCRS) is Nova Scotia’s current framework for providing location-based information. The NSCRS is the foundation for the province’s geographic data, including the land administration system. In 2012, the province began developing a modernization strategy to better execute its coordinate referencing program to address ongoing accuracy and accessibility needs. A network of active control stations (ACSs) tracking global navigation satellite systems (GNSS) is at the core of the new strategy. In addition to providing better accuracy and accessibility to the NSCRS, the technology has created new opportunities to sustain its passive control infrastructure. In 2015, the installation of 40 ACSs across the province was completed, providing industry with access to real-time, centimetre-level positioning. Over the course of the NSCRS modernization project, several technical considerations needed to be addressed pertaining to the design of the network, location of the ACSs, flow of the ACS data and the crowd sourcing of GNSS observation data to maintain the passive control system. These technical considerations are reviewed and the solutions implemented to address the needs of this initiative are presented. Numéro de notice : A2016-677 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.5623/cig2016-201 En ligne : http://dx.doi.org/10.5623/cig2016-201 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81931 [article]

Boresight and lever arm calibration of a mobile terrestrial Lidar system / M. Leslar in Geomatica, vol 70 n° 2 (June 2016)  

Public [article]  inGeomatica > vol 70 n° 2 (June 2016) . - pp 97 - 112 Titre : Boresight and lever arm calibration of a mobile terrestrial Lidar system Type de document : Article/Communication Auteurs : M. Leslar, Auteur ; J.G. Wang, Auteur ; B. Hu, Auteur Année de publication : 2016 Article en page(s) : pp 97 - 112 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] acquisition de données [Termes IGN] acquisition simultanée [Termes IGN] angle de visée [Termes IGN] données lidar [Termes IGN] étalonnage de capteur (imagerie) [Termes IGN] point d'appui [Termes IGN] surface plane [Termes IGN] télémétrie laser terrestre Résumé : (auteur) Unlike Mobile Airborne LiDAR (MAL), it has become common for Mobile Terrestrial LiDAR (MTL) systems to consist of two or more LiDAR sensors. It is a challenging task for a user to simultaneously verify and calibrate their lever arms and boresight angles with respect to the IMU using the kinematic data. This paper presents a novel method for determination of MTL calibration parameters using the vector geometry created by a stereo pair of MTL sensors. Through the use of the stereo information provided by a pair of MTL sensors working in tandem, system parameters such as lever arm and boresight angles can be determined for both sensors based on a single pass of a calibration object or scene. In this way, any data collected by a multi-sensor MTL can potentially be used to calibrate the system. Unlike many other calibration methods for calibrating MTL and MAL systems, the proposed method enables the simultaneous calibration of all lever arm and bore sight parameters for all of the LiDAR sensors integrated into the MTL system. Many MTL systems do not make it easy for end users to measure the lever arms, usually forcing users to fall back on mechanical drawings to determine the lever arms. The calibration method has been realized using test data acquired by two independent Lynx Mobile Mapper systems on 1) a single pass of a typical 400-m-long urban street scene and 2) a single pass around a calibration building. Each experiment succeeded at producing arc - second accurate boresight and sub-centimetre accurate lever arm parameters. Several scenarios were run. It was found that this accuracy level could be practically maintained with a control field consisting of five to seven control points distributed on horizontal and vertical surfaces. Numéro de notice : A2016-678 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.5623/cig2016-202 En ligne : http://dx.doi.org/10.5623/cig2016-202 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81932 [article]

Single-frequency precise point positioning using multi-constellation GNSS: GPS, Glonass, Galileo and Beidou / Mahmoud Abd Rabbou in Geomatica, vol 70 n° 2 (June 2016)  

Public [article]  inGeomatica > vol 70 n° 2 (June 2016) . - pp 113 - 122 Titre : Single-frequency precise point positioning using multi-constellation GNSS: GPS, Glonass, Galileo and Beidou Type de document : Article/Communication Auteurs : Mahmoud Abd Rabbou, Auteur ; Ahmed El-Rabbany, Auteur Année de publication : 2016 Article en page(s) : pp 113 - 122 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] constellation GNSS [Termes IGN] modèle ionosphérique [Termes IGN] positionnement par GNSS [Termes IGN] positionnement ponctuel précis Résumé : (auteur) Single-frequency precise point positioning (PPP) presents a cost-effective positioning technique for a large number of users. However, it possesses low positioning accuracy and convergence time compared with the dual-frequency PPP. Single-frequency PPP commonly employs GPS satellite systems that suffer from poor satellite geometry, especially in dense urban areas. We develop a new single-frequency PPP model that combines the observations of current GNSS constellations, including GPS, GLONASS, Galileo and Beidou. The MGEX IGS final precise products are utilized to account for the orbital and clock errors, while the IGS final global ionospheric maps (GIM) model is used to correct for the ionospheric delay. The GNSS inter-system biases are treated as additional unknowns in the estimation process. The contribution of the additional GNSS observations to single-frequency PPP is assessed through solution comparison with its traditional GPS-only counterpart. Various GNSS combinations are considered in the assessment, including GPS/GLONASS, GPS/Galileo, GPS/BeiDou and all-constellation GNSS. It is shown that the additional GNSS observations enhance the PPP solution accuracy and convergence time in comparison with the traditional GPS-only solution. Except for stations with a sufficient number of tracked BeiDou satellites, both Galileo and BeiDou have marginal effects on the positioning accuracy due to their limited number of satellites. However, for stations with a sufficient number of visible BeiDou satellites, an average of 40% PPP accuracy improvement is obtained. The major contribution to the PPP accuracy enhancement is obtained from GLONASS satellite observations. Numéro de notice : A2016-679 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.5623/cig2016-203 En ligne : http://dx.doi.org/10.5623/cig2016-203 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81933 [article]