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Real time monitoring ground motion using GPS with real time corrections / R. Tu in Survey review, vol 48 n° 347 (March 2016)  

Public [article]  inSurvey review > vol 48 n° 347 (March 2016) . - pp 79 – 85 Titre : Real time monitoring ground motion using GPS with real time corrections Type de document : Article/Communication Auteurs : R. Tu, Auteur ; L. Wang, Auteur ; Z. Liu, Auteur Année de publication : 2016 Article en page(s) : pp 79 – 85 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] modèle d'erreur [Termes IGN] mouvement de terrain [Termes IGN] positionnement par GPS [Termes IGN] résidu [Termes IGN] station GPS [Termes IGN] surveillance géologique [Termes IGN] vitesse Résumé : (auteur) The high rate GPS velocity determination technology which is based on the broadcast ephemeris and epoch differenced model can retrieve displacement of ground motion with the precision of a few centimetres to decimetres in real time. Moreover, the precision of the recovered displacement can be improved if the un-modelled errors such as broadcast ephemeris residuals, atmospheric residuals, multipath effects and high frequency noise are tackled more accurately. In this paper, we propose a method to improve the precision of the recovered displacement by appropriately making use of reference station corrections. For the reference stations, the coordinates are highly constrained to extract the error corrections that are to be broadcast via a communication link to the rover. After correcting the rover’s observations, some errors such as ephemeris residuals and atmospheric residuals are effectively eliminated or at least reduced. This improves the accuracy of the observations and thus enhances the reliability of the velocity estimation. The displacement can be recovered by integrating the estimated velocity after de-trending using a linear trend that is caused by the un-corrected residuals. The series of validation results in the experiment have shown that the displacement of the simulated motion can be real time recovered with a precision of 1–2 cm, and is thus applicable for real time monitoring of the ground motion. Numéro de notice : A2016-047 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270614Y.0000000141 En ligne : https://doi.org/10.1179/1752270614Y.0000000141 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79641 [article]

The use of laser scanning as a method for measuring stairways following an accident / M. Eyre in Survey review, vol 48 n° 347 (March 2016)  

Public [article]  inSurvey review > vol 48 n° 347 (March 2016) . - pp 121 - 129 Titre : The use of laser scanning as a method for measuring stairways following an accident Type de document : Article/Communication Auteurs : M. Eyre, Auteur ; P. J. Foster, Auteur ; K. Hallas, Auteur ; R. Shaw, Auteur Année de publication : 2016 Article en page(s) : pp 121 - 129 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Topographie moderne [Termes IGN] analyse spatiale [Termes IGN] architecture [Termes IGN] carte d'intérieur [Termes IGN] dommage physique [Termes IGN] inclinomètre (topographie) [Termes IGN] lever des détails [Termes IGN] reconstruction 3D [Termes IGN] surveillance d'ouvrage [Termes IGN] télémétrie laser terrestre Résumé : (auteur) Stairs present significant potential for harm to their users. A fall on stairs, particularly in descent, often leads to serious injury or even death. The authors have been involved in the investigation of many workplace stair accidents. Proper forensic investigation into the cause of a stair accident has often found the incident to be wholly or partly caused by poor stair design. In order to establish the relationship between the stair design and a given fall, an onsite survey has to be conducted, determining the rises and goings along with other key dimensions. The Health and Safety Laboratory (HSL), Buxton, UK, regularly undertake this type of survey using a digital inclinometer, a steel rule and a tape measure. Laser scanning is an emerging technique that is now accessible to the surveyor to complement or replace traditional approaches. The laser scanner and associated software produces a dense point survey in 3D, allowing dimensional analysis of the features. The authors used both traditional and laser scanning techniques to study the scenes of two fatal stair falls. The analysis presented allows the suitability of laser scanning for stair-fall investigation to be considered. Identification and classification of errors are needed in order to consider if the error is acceptable or can be mitigated. Laser scanners are impressive instruments providing data from which can be used to create a virtual 3D environment that can be used to reconstruct and explain an event and contributing factors. The use of both survey methods currently provides the investigator with complimentary data that allows accurate measurements to be presented in the context of the three-dimensional environment. Numéro de notice : A2016-048 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270615Y.0000000014 En ligne : https://doi.org/10.1179/1752270615Y.0000000014 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79642 [article]