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Detection of high speed railway track static regularity with laser trackers / L. Yao in Survey review, vol 47 n° 343 (July 2015)  

Public [article]  inSurvey review > vol 47 n° 343 (July 2015) . - pp 279 - 285 Titre : Detection of high speed railway track static regularity with laser trackers Type de document : Article/Communication Auteurs : L. Yao, Auteur ; H. Sun, Auteur ; Y. Zhou, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 279 - 285 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] capteur à balayage [Termes IGN] précision submillimétrique [Termes IGN] statique [Termes IGN] surveillance d'ouvrage [Termes IGN] train à grande vitesse [Termes IGN] voie ferrée Résumé : (auteur) Track regularity is of vital importance in the safety of high speed railway operation. A laser tracker can collect highly accurate three-dimensional (3D) point measurements. Therefore, it is considered as a promising surveying technique for the detection of railway track static irregularity as opposed to using a total station. This study proposes a new approach that uses a laser tracker as the main sensor for obtaining the coordinates of left- and right-track points to detect potential track static irregularities. In this method, the reflecting target of the laser tracker is on a track inspection trolley moving in a round trip along the railway track. A field experiment was conducted to validate the results by comparing the results with the field measurements gathered using a track inspection trolley. The results show that the track static regularity detection method with laser trackers is feasible and indicate that track geometry parameters such as gauges, elevations and lateral deviations of centreline, superelevations, lateral profiles and vertical profiles obtained using the laser tracker and a track inspection trolley are in a good agreement. The average of deviations of track centreline elevations, lateral deviations, and gauges are 0·8, 0·7 and 0·3 mm. Numéro de notice : A2015-922 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1179/1752270614Y.0000000135 En ligne : https://doi.org/10.1179/1752270614Y.0000000135 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=79733 [article]

A partition-based serial algorithm for generating viewshed on massive DEMs / H. Wu in International journal of geographical information science IJGIS, vol 21 n° 9-10 (october 2007)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 21 n° 9-10 (october 2007) . - pp 955 - 964 Titre : A partition-based serial algorithm for generating viewshed on massive DEMs Type de document : Article/Communication Auteurs : H. Wu, Auteur ; M. Pan, Auteur ; L. Yao, Auteur ; B. Luo, Auteur Année de publication : 2007 Article en page(s) : pp 955 - 964 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] algorithme géométrique [Termes IGN] modèle numérique de surface [Termes IGN] partitionnement par bloc Résumé : (Auteur) As increasingly large-scale and higher-resolution terrain data have become available, for example air-form and space-borne sensors, the volume of these datasets reveals scalability problems with existing GIS algorithms. To address this problem, a kind of serial algorithm was developed to generate viewshed on large grid-based digital elevation models (DEMs). We first divided the whole DEM into rectangular blocks in row and column directions (called block partitioning), then processed these blocks with four axes followed by four sectors sequentially. When processing the particular block, we adopted the 'reference plane' algorithm to calculate the visibility of the target point on the block, and adjusted the calculation sequence according to the different spatial relationships between the block and the viewpoint since the viewpoint is not always inside the DEM. By adopting the 'Reference Plane' algorithm and using a block partitioning method to segment and load the DEM dynamically, it is possible to generate viewshed efficiently in PC-based environments. Experiments showed that the divided block should be dynamically loaded whole into computer main memory when partitioning, and the suggested approach retains the accuracy of the reference plane algorithm and has near linear compute complexity. Copyright Taylor & Francis Numéro de notice : A2007-551 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/13658810601034218 En ligne : https://doi.org/10.1080/13658810601034218 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=28914 [article]

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-07061	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-07062	RAB	Revue	Centre de documentation	En réserve L003	Disponible