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Analysis of the repeated absolute gravity measurements in the Czech Republic, Slovakia and Hungary from the period 1991–2010 considering instrumental and hydrological effects / S. Zhang in Journal of geodesy, vol 87 n° 1 (January 2013)  

Public [article]  inJournal of geodesy > vol 87 n° 1 (January 2013) . - pp 29 - 42 Titre : Analysis of the repeated absolute gravity measurements in the Czech Republic, Slovakia and Hungary from the period 1991–2010 considering instrumental and hydrological effects Type de document : Article/Communication Auteurs : S. Zhang, Auteur ; X. Tong, Auteur ; K. Zhang, Auteur Année de publication : 2013 Article en page(s) : pp 29 - 42 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse diachronique [Termes IGN] erreur instrumentale [Termes IGN] gravimètre absolu [Termes IGN] Hongrie [Termes IGN] hydrologie [Termes IGN] levé gravimétrique [Termes IGN] République Tchèque [Termes IGN] Slovaquie Résumé : (Auteur) Since August 2001, the absolute gravimeter FG5#215 has been used for the modernization of the national gravity networks of the Czech Republic, Slovakia, and Hungary. Altogether 43 absolute stations were measured, some of them repeatedly. Absolute gravity at 29 stations had already been determined in 1990s by other absolute gravimeters (FG5 or JILAg). Differences of repeated measurements at most of the stations show an unexpected decrease of gravity (up to 22 uGal) over the whole region. An uncertainty assessment of absolute measurements with a special emphasis put on hydrological effects shows a statistical significance of the detected gravity variations at many stations. In this manuscript, three possible reasons of such findings are discussed: (1) a regional geodynamic activity, (2) systematic instrumental errors (offsets), (3) hydrological effects. The analysis and statistics of the gravity differences in context of international comparisons of absolute gravimeters show offsets up to 9 uGal related to data of the JILAg-6 and FG5#107 gravimeters. Data collected in this study demonstrate that considering instrumental and hydrological effects on gravity are crucial for a correct interpretation of repeated absolute gravity measurements. Numéro de notice : A2013-072 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0576-1 Date de publication en ligne : 24/06/2012 En ligne : https://doi.org/10.1007/s00190-012-0576-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32210 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2013011	SL	Revue	Centre de documentation	Revues en salle	Disponible

Building-damage detection using pre- and post-seismic high-resolution satellite stereo imagery: A case study of the May 2008 Wenchuan earthquake / X. Tong in ISPRS Journal of photogrammetry and remote sensing, vol 68 (March 2012)  

Public [article]  inISPRS Journal of photogrammetry and remote sensing > vol 68 (March 2012) . - pp 13 - 27 Titre : Building-damage detection using pre- and post-seismic high-resolution satellite stereo imagery: A case study of the May 2008 Wenchuan earthquake Type de document : Article/Communication Auteurs : X. Tong, Auteur ; Z. Hong, Auteur ; S. Liu, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 13 - 27 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] analyse comparative [Termes IGN] analyse diachronique [Termes IGN] bati [Termes IGN] détection de changement [Termes IGN] dommage matériel [Termes IGN] hauteur du bâti [Termes IGN] image Ikonos [Termes IGN] modèle numérique de surface [Termes IGN] séisme [Termes IGN] Setchouan (Chine) Résumé : (Auteur) To address the disadvantage of traditional methods providing only two-dimensional (2D) damage change of the collapsed buildings, this paper presents an approach for the detection of the buildings that have collapsed in an earthquake based on 3D geometric changes, particularly height change of the buildings, using pre- and post-seismic IKONOS stereo image pairs. One of the critical issues – the accuracy of the 3D ground point determination from high-resolution satellite imagery (HRSI) – is first addressed employing a bias-compensation model based on the rational function polynomial coefficient bundle adjustment. With the refined 3D ground coordinates, two ways of detecting the collapsed buildings are proposed: (1) detection of an individual collapsed building by comparing the height differences at the corner points of the building calculated from the pre- and post-seismic IKONOS stereo pairs and (2) determination of the region of collapsed buildings by calculating the difference between the pre- and post-seismic digital elevation models (DEMs) generated again from the pre- and post-seismic stereo images. At the same time, a pre-seismic DEM based on a topographical map is generated for detection comparison in the study. The experiment results for Dujiangyan using two IKONOS stereo pairs before and after the Wenchuan earthquake demonstrated the following. (1) Accuracy of better than 1.1 m in planimetry and 1.5 m in height can be achieved from the pre- and post-seismic IKONOS stereo image pairs using the affine bias compensation model. This accuracy guarantees the feasibility of detecting the 3D geometric changes of the earthquake-induced building collapses from pre- and post-seismic HRSI stereo images. (2) Using the refined 3D coordinates of the ground points computed from the pre- and post-seismic IKONOS stereo pairs, the status (i.e., totally collapsed, partially collapsed or not collapsed) and the number of collapsed storeys can be estimated for an individual building being assessed. (3) The region of collapsed buildings can be determined by differencing the pre- and post-seismic DEMs created from the pre- and post-seismic IKONOS stereo pairs. An overall accuracy of better than 90% is achieved for the detection of the collapsed buildings based on the difference DEM using the pixel- and object-based assessment methods. Numéro de notice : A2012-145 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2011.12.004 En ligne : https://doi.org/10.1016/j.isprsjprs.2011.12.004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31592 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
081-2012021	SL	Revue	Centre de documentation	Revues en salle	Disponible

Introducing scale parameters for adjusting area objects in GIS based on least squares and variance component estimation / X. Tong in International journal of geographical information science IJGIS, vol 23 n°11-12 (november 2009)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 23 n°11-12 (november 2009) . - pp 1413 - 1432 Titre : Introducing scale parameters for adjusting area objects in GIS based on least squares and variance component estimation Type de document : Article/Communication Auteurs : X. Tong, Auteur ; Wei Shi, Auteur ; D. Liu, Auteur Année de publication : 2009 Article en page(s) : pp 1413 - 1432 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG [Termes IGN] cadastre numérique [Termes IGN] cohérence des données [Termes IGN] compensation par moindres carrés [Termes IGN] coordonnées géographiques [Termes IGN] erreur systématique [Termes IGN] facteur d'échelle [Termes IGN] interpolation par pondération de zones [Termes IGN] numérisation du cadastre [Termes IGN] objet géographique zonal [Termes IGN] parcelle cadastrale [Termes IGN] système d'information géographique [Termes IGN] variance Résumé : (Auteur) In this paper, a least-squares based cadastral parcel area adjustment in geographic information systems (GIS) is developed based on (1) both the areas and coordinates being treated as observations with errors; and (2) scale parameters being introduced to take the systematic effect into account in the process of cadastral map digitization. The area condition equation for cadastral parcel considerations of scale parameters and geometric constraints is first constructed. The effects of the scale error on area adjustment results are then derived, and statistical hypothesis testing is presented to determine the significance of the scale error. Afterwards, Helmert's variance component estimation based on least-squares adjustment using the condition equation with additional parameters is proposed to determine the weight between the coordinate and area measurements of the parcel. Practical tests are conducted to illustrate the implementation of the proposed methods. Four schemes for solving the inconsistencies between the registered areas and the digitized areas of the parcels are studied. The analysis of the results demonstrates that in the case of significant systematic errors in cadastral map digitization, the accuracies of the adjusted coordinates and areas are improved by introducing scale parameters to reduce the systematic error influence in the parcel area adjustment. Meanwhile, Helmert's variance component estimation method determines more accurate weights of the digitized coordinates and parcel areas, and the least-squares adjustment solves the inconsistencies between the registered areas and the digitized areas of the parcels. Numéro de notice : A2009-514 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810802077826 En ligne : https://doi.org/10.1080/13658810802077826 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=30143 [article]

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
079-09071	RAB	Revue	Centre de documentation	En réserve L003	Disponible
079-09072	RAB	Revue	Centre de documentation	En réserve L003	Disponible