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Analysis of ocean tide loading displacements by GPS kinematic precise point positioning: a case study at the China coastal site SHAO / H. Zhao in Survey review, vol 51 n° 365 (March 2019)  

Public [article]  inSurvey review > vol 51 n° 365 (March 2019) . - pp 172 - 182 Titre : Analysis of ocean tide loading displacements by GPS kinematic precise point positioning: a case study at the China coastal site SHAO Type de document : Article/Communication Auteurs : H. Zhao, Auteur ; Q. Zhang, Auteur ; R. Tu, Auteur ; Z. Liu, Auteur Année de publication : 2019 Article en page(s) : pp 172 - 182 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] analyse spectrale [Termes IGN] Chine [Termes IGN] données GPS [Termes IGN] données marégraphiques [Termes IGN] GPS en mode cinématique [Termes IGN] littoral [Termes IGN] marée océanique [Termes IGN] positionnement ponctuel précis [Termes IGN] série temporelle [Termes IGN] surcharge océanique Résumé : (Auteur) Ocean tide loading (OTL) displacement amplitudes and phase lags of SHAO site are estimated by global positioning system (GPS), kinematic precise point positioning (PPP) and spectral analysis using 19 years of continuous GPS observations. In kinematic PPP, the 66 additional harmonic displacement parameters are replaced by the three time-varying displacement parameters without a priori modelled OTL displacements. By comparing the results with predictions from hybrid regional/global models, we are able to demonstrate that GPS/model agreements are at the level of 0.2 mm (horizontal) and 0.6 mm (vertical) for the four lunar constituents, 0.4 mm (horizontal) and 1.35 mm (vertical) for the four solar/sidereal constituents, and 0.2 mm (horizontal) and 0.3 mm (vertical) for the three long-period constituents. Finally, we conclude that GPS-derived lunar constituents can substitute for the model corrections in GPS data processing and the accuracy of GPS-derived solar/sidereal constituents needs to be improved by further studies. Numéro de notice : A2019-190 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2017.1407392 Date de publication en ligne : 30/11/2017 En ligne : https://doi.org/10.1080/00396265.2017.1407392 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92634 [article]

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]

Voxel-optimized regional water vapor tomography and comparison with radiosonde and numerical weather model / Biyan Chen in Journal of geodesy, vol 88 n° 7 (July 2014)  

Public [article]  inJournal of geodesy > vol 88 n° 7 (July 2014) . - pp 691 - 703 Titre : Voxel-optimized regional water vapor tomography and comparison with radiosonde and numerical weather model Type de document : Article/Communication Auteurs : Biyan Chen, Auteur ; Z. Liu, Auteur Année de publication : 2014 Article en page(s) : pp 691 - 703 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] positionnement par GNSS [Termes IGN] tomographie [Termes IGN] vapeur d'eau [Termes IGN] voxel Résumé : (Auteur)Water vapor tomography has been developed as a powerful tool to model spatial and temporal distribution of atmospheric water vapor. Global navigation satellite systems (GNSS) water vapor tomography refers to the 3D structural construction of tropospheric water vapor using a large number of GNSS signals that penetrate the tomographic modeling area from different positions. The modeling area is usually discretized into a number of voxels. A major issue involved is that some voxels are not crossed by any GNSS signal rays, resulting in an undetermined solution to the tomographic system. To alleviate this problem, the number of voxels crossed by GNSS signal rays should be as large as possible. An important way to achieve this is to optimize the geographic distribution of tomographic voxels. We propose an approach to optimize voxel distribution in both vertical and horizontal domains. In the vertical domain, water vapor profiles derived from radiosonde data are exploited to identify the maximum height of tomography and the optimal vertical resolution. In the horizontal domain, the optimal horizontal distribution of voxels is obtained by searching the maximum number of ray-crossing voxels in both latitude and longitude directions. The water vapor tomography optimization procedures are implemented using GPS water vapor data from the Hong Kong Satellite Positioning Reference Station Network. The tomographic water vapor fields solved from the optimized tomographic voxels are evaluated using radiosonde data and a numerical weather prediction non-hydrostatic model (NHM) obtained for the Hong Kong station. The comparisons of tomographic integrated water vapor (IWV) with the radiosonde and NHM IWV show that RMS errors of their differences are 1.41 and 3.09 mm, respectively. Moreover, the tomographic water vapor density results are compared with those of radiosonde and NHM. The RMS error of the density differences between tomography and radiosonde data is 1.05 g/m3 . For the comparison between tomography and NHM, an overall RMS error of 1.43g/m3 is achieved. Numéro de notice : A2014-415 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0713-0 Date de publication en ligne : 08/04/2014 En ligne : https://doi.org/10.1007/s00190-014-0713-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=73956 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2014071	SL	Revue	Centre de documentation	Revues en salle	Disponible

A simple and robust feature point matching algorithm based on restricted spatial order constraints for aerial image registration / Z. Liu in IEEE Transactions on geoscience and remote sensing, vol 50 n° 2 (February 2012)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 50 n° 2 (February 2012) . - pp 514 - 527 Titre : A simple and robust feature point matching algorithm based on restricted spatial order constraints for aerial image registration Type de document : Article/Communication Auteurs : Z. Liu, Auteur ; J. An, Auteur ; Y. Jing, Auteur Année de publication : 2012 Article en page(s) : pp 514 - 527 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image mixte [Termes IGN] appariement de graphes [Termes IGN] appariement de points [Termes IGN] image aérienne [Termes IGN] image optique [Termes IGN] image radar moirée [Termes IGN] programmation par contraintes [Termes IGN] superposition d'images [Termes IGN] valeur aberrante Résumé : (Auteur) Accurate point matching is a critical and challenging process in feature-based image registration. In this paper, a simple and robust feature point matching algorithm, called Restricted Spatial Order Constraints (RSOC), is proposed to remove outliers for registering aerial images with monotonous backgrounds, similar patterns, low overlapping areas, and large affine transformation. In RSOC, both local structure and global information are considered. Based on adjacent spatial order, an affine invariant descriptor is defined, and point matching is formulated as an optimization problem. A graph matching method is used to solve it and yields two matched graphs with a minimum global transformation error. In order to eliminate dubious matches, a filtering strategy is designed. The strategy integrates two-way spatial order constraints and two decision criteria restrictions, i.e., the stability and accuracy of transformation error. Twenty-nine pairs of optical and Synthetic Aperture Radar (SAR) aerial images are utilized to evaluate the performance. Compared with RANdom SAmple Consensus (RANSAC), Graph Transformation Matching (GTM), and Spatial Order Constraints (SOC), RSOC obtained the highest precision and stability. Numéro de notice : A2012-046 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2011.2160645 Date de publication en ligne : 04/08/2011 En ligne : https://doi.org/10.1109/TGRS.2011.2160645 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31494 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2012021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Using satellite imagery and GIS for land-use and land-cover change mapping in an estuarine watershed / X. Yang in International Journal of Remote Sensing IJRS, vol 26 n° 23 (December 2005)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 26 n° 23 (December 2005) . - pp 5275 - 5296 Titre : Using satellite imagery and GIS for land-use and land-cover change mapping in an estuarine watershed Type de document : Article/Communication Auteurs : X. Yang, Auteur ; Z. Liu, Auteur Année de publication : 2005 Article en page(s) : pp 5275 - 5296 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] analyse diachronique [Termes IGN] baie [Termes IGN] bassin hydrographique [Termes IGN] carte d'occupation du sol [Termes IGN] carte thématique [Termes IGN] changement d'occupation du sol [Termes IGN] classification [Termes IGN] classification ascendante hiérarchique [Termes IGN] croissance urbaine [Termes IGN] dégradation de l'environnement [Termes IGN] écosystème [Termes IGN] estuaire [Termes IGN] image Landsat-ETM+ [Termes IGN] image Landsat-TM [Termes IGN] littoral [Termes IGN] Mexique (golfe du) [Termes IGN] précision de la classification [Termes IGN] protection de l'environnement [Termes IGN] système d'information géographique Résumé : (Auteur) The degradation of world-wide estuarine ecosystems as a result of accelerated human population growth accompanied by agricultural, industrial and urban development justifies a strong need to find efficient ways to manage and protect these sensitive environments. Starting from 2001. the authors have been involved in an interdisciplinary research project aiming to develop environmental indicators for integrated estuarine ecosystem assessment in the Gulf of Mexico. As part of this project, a study was conducted to characterize land-use and land-cover changes with the Pensacola estuarine drainage area as a case. The Pensacola bay was targeted because it is one of few exemplary large river-driven estuarine systems across the northern Gulf of Mexico. The study had two major sections. The first part was dedicated to the development of an improved method for coastal land-use and land-cover mapping, which was built upon hierarchical classification and spatial reclassification. An image scene was separated into urban and rural regions early in the classification, with a 'mask' defined by road intersection density slices combined with road buffers. Each part was classified independently in its most effective context and, later, both were merged to form a complete map. In spatial reclassification, image interpretation procedures, auxiliary vector data and a variety of Geographical Information System (GIS) functions were synthesized to resolve spectral confusion and improve mapping accuracy. This method was used to map land use and land cover from Landsat Thematic Mapper/Enhanced Thernatic Mapper Plus (TM/ETM +) imagery for 1989, 1996 and 2002, respectively. The accuracy assessment shows that the overall classification errors were less than 10%. The second part focused on the analysis of the spatio-temporal dynamics of estuarine land-use and land-cover changes by using post-classification comparison and GIS overlay techniques. The project has revealed that a substantial growth of low-density urban land occurred in the lower drainage basin in connection with population and housing growth, as well as a significant increase of mixed forest land in the upper watershed as a result of active logging and harvesting operations. These growths were achieved at the cost of evergreen forest and wetlands, thus compromising safeguards for water quality, biodiversity of aquatic systems, habitat structure and watershed health in the Pensacola estuarine drainage area. Numéro de notice : A2005-517 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/01431160500219224 En ligne : https://doi.org/10.1080/01431160500219224 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=27653 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-05231	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt