Centre de documentation
scientifique

Detecting and analyzing mobility hotspots using surface networks / Y. Hu in Transactions in GIS, vol 18 n° 6 (December 2014)  

Public [article]  inTransactions in GIS > vol 18 n° 6 (December 2014) . - pp 911 – 935 Titre : Detecting and analyzing mobility hotspots using surface networks Type de document : Article/Communication Auteurs : Y. Hu, Auteur ; Harvey J. Miller, Auteur ; X. Li, Auteur Année de publication : 2014 Article en page(s) : pp 911 – 935 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] estimation par noyau [Termes IGN] mobilité humaine [Termes IGN] objet mobile [Termes IGN] Shanghai (Chine) [Termes IGN] théorie des graphes [Termes IGN] topologie Résumé : (Auteur) Capabilities for collecting and storing data on mobile objects have increased dramatically over the past few decades. A persistent difficulty is summarizing large collections of mobile objects. This article develops methods for extracting and analyzing hotspots or locations with relatively high levels of mobility activity. We use kernel density estimation (KDE) to convert a large collection of mobile objects into a smooth, continuous surface. We then develop a topological algorithm to extract critical geometric features of the surface; these include critical points (peaks, pits and passes) and critical lines (ridgelines and course-lines). We connect the peaks and corresponding ridgelines to produce a surface network that summarizes the topological structure of the surface. We apply graph theoretic indices to analytically characterize the surface and its changes over time. To illustrate our approach, we apply the techniques to taxi cab data collected in Shanghai, China. We find increases in the complexity of the hotspot spatial distribution during normal activity hours in the late morning, afternoon and evening and a spike in the connectivity of the hotspot spatial distribution in the morning as taxis concentrate on servicing travel to work. These results match with scientific and anecdotal knowledge about human activity patterns in the study area. Numéro de notice : A2014-577 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/tgis.12076 Date de publication en ligne : 17/02/2014 En ligne : https://doi.org/10.1111/tgis.12076 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74767 [article]

Recovering quantitative remote sensing products contaminated by thick clouds and shadows using multitemporal dictionary learning / X. Li in IEEE Transactions on geoscience and remote sensing, vol 52 n° 11 tome 1 (November 2014)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 52 n° 11 tome 1 (November 2014) . - pp 7086 - 7098 Titre : Recovering quantitative remote sensing products contaminated by thick clouds and shadows using multitemporal dictionary learning Type de document : Article/Communication Auteurs : X. Li, Auteur ; H. Shen, Auteur ; L. Zhang, Auteur ; et al., Auteur Année de publication : 2014 Article en page(s) : pp 7086 - 7098 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] apprentissage (cognition) [Termes IGN] détection d'ombre [Termes IGN] réflectance [Termes IGN] température de surface Résumé : (Auteur) With regard to quantitative remote sensing products in the visible and infrared ranges, thick clouds and accompanying shadows are an inevitable source of noise. Due to the absence of adequate supporting information from the data themselves, it is a formidable challenge to accurately restore the surficial information underlying large-scale clouds. In this paper, dictionary learning is expanded into the multitemporal recovery of quantitative data contaminated by thick clouds and shadows. This paper proposes two multitemporal dictionary learning algorithms, expanding on their KSVD and Bayesian counterparts. In order to make better use of the temporal correlations, the expanded KSVD algorithm seeks an optimized temporal path, and the expanded Bayesian method adaptively weights the temporal correlations. In the experiments, the proposed algorithms are applied to a reflectance product and a land surface temperature product, and the respective advantages of the two algorithms are investigated. The results show that, from both the qualitative visual effect and the quantitative objective evaluation, the proposed methods are effective. Numéro de notice : A2014-543 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2307354 En ligne : https://doi.org/10.1109/TGRS.2014.2307354 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74160 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2014111A	RAB	Revue	Centre de documentation	En réserve L003	Disponible

An underground-mining detection system based on DInSAR / Z. Hu in IEEE Transactions on geoscience and remote sensing, vol 51 n° 1 Tome 2 (January 2013)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 51 n° 1 Tome 2 (January 2013) . - pp 615 - 625 Titre : An underground-mining detection system based on DInSAR Type de document : Article/Communication Auteurs : Z. Hu, Auteur ; Linlin Ge, Auteur ; X. Li, Auteur ; et al., Auteur Année de publication : 2013 Article en page(s) : pp 615 - 625 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] carrière souterraine [Termes IGN] Chine [Termes IGN] image ALOS-PALSAR [Termes IGN] image radar moirée [Termes IGN] interferométrie différentielle [Termes IGN] mine de charbon [Termes IGN] subsidence Résumé : (Auteur) Underground mining easily causes casualties, and illegal mining is a major contributor to this issue. It is a challenge to locate and differentiate illegal mines from approved mines over a vast area. Over the past few years, our research in satellite differential radar interferometry (DInSAR) to monitor underground-mine-induced surface subsidence has demonstrated the reliability of DInSAR. In this paper, a DInSAR-based illegal-mining detection system (DIMDS) is proposed to exploit the geometric, spatial, and temporal characteristics of those subsidence patterns. Testing results over a coalfield in Asia have proven the efficiency, reliability, and cost effectiveness of DIMDS in finding out illegal mines. Numéro de notice : A2013-018 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2012.2202243 En ligne : https://doi.org/10.1109/TGRS.2012.2202243 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32156 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2013011B	RAB	Revue	Centre de documentation	En réserve L003	Disponible

3D coseismic displacement of 2010 Darfield, New Zealand earthquake estimated from multi-aperture InSAR and D-InSAR measurements / J. Hu in Journal of geodesy, vol 86 n° 11 (November 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 11 (November 2012) . - pp 1029 - 1041 Titre : 3D coseismic displacement of 2010 Darfield, New Zealand earthquake estimated from multi-aperture InSAR and D-InSAR measurements Type de document : Article/Communication Auteurs : J. Hu, Auteur ; X. Li, Auteur ; X. Ding, Auteur ; et al., Auteur Année de publication : 2012 Article en page(s) : pp 1029 - 1041 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] déformation de la croute terrestre [Termes IGN] données localisées 3D [Termes IGN] faille géologique [Termes IGN] image ALOS-PALSAR [Termes IGN] image radar moirée [Termes IGN] interferométrie différentielle [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] Nouvelle-Zélande [Termes IGN] propagation ionosphérique [Termes IGN] séisme Résumé : (Auteur) Differential interferometric synthetic aperture radar (D-InSAR) measures ground deformation only along the line-of-sight (LOS) of the radar, which limits the capability of D-InSAR in investigating the surface damages and the focus mechanisms of earthquakes. We do a three-dimensional (3D) decomposition of the coseismic displacement of the Darfield, New Zealand earthquake that occurred on 3 September 2010 by exploiting the Multi-Aperture InSAR (MAI) and D-InSAR measurements from both ascending and descending L-band PALSAR data. Due to the dispersive nature of the ionosphere and the slight Doppler shift between the forward- and backward-looking interferograms, the ionospheric effects can be more serious in MAI measurements than in D-InSAR. We propose mitigating the ionospheric effects in the MAI processing with the directional filtering and interpolation procedure that has been applied in Offset-tracking. The rupture revealed by the 3D surface displacement fits closely to the Greendale fault, which is believed to be responsible for the earthquake. The horizontal ground motions, mostly eastwards in the hanging wall and westwards in the footwall, reached up to 2.5 m and are anti-symmetric with respect to the Greendale fault. Up to 2.5 m subsidence occurred in the hanging wall, while uplift is found in the footwall with an extreme case of 1.6 m in the far left of the fault. This makes us conclude that the Greendale fault is a normal and dextral strike-slip. It is seen that the MAI measurements are very helpful in the derivation of 3D coseismic displacement fields as it provides more accurate displacement estimation in the north–south direction. Numéro de notice : A2012-578 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-012-0563-6 Date de publication en ligne : 20/04/2012 En ligne : https://doi.org/10.1007/s00190-012-0563-6 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32024 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012111	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Strapdown INS/DGPS airborne gravimetry tests in the Gulf of Mexico / X. Li in Journal of geodesy, vol 85 n° 9 (September 2011)  

Public [article]  inJournal of geodesy > vol 85 n° 9 (September 2011) . - pp 597 - 605 Titre : Strapdown INS/DGPS airborne gravimetry tests in the Gulf of Mexico Type de document : Article/Communication Auteurs : X. Li, Auteur Année de publication : 2011 Article en page(s) : pp 597 - 605 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] centrale inertielle [Termes IGN] données GPS [Termes IGN] force de gravitation [Termes IGN] GPS en mode différentiel [Termes IGN] GPS-INS [Termes IGN] gravimétrie aérienne [Termes IGN] Mexique (golfe du) [Termes IGN] test de performance Résumé : (Auteur) Combining data from a Strapdown Inertial Navigation System and a Differential Global Positioning System (SINS/DGPS) has shown great promise in estimating gravity on moving platforms. Previous studies on a ground-vehicle system obtained 1–3 mGal precision with 2 km spatial resolution. High-accuracy Inertial Measurement Units (IMU) and cm-level positioning solutions are very important in obtaining mGal-level gravity disturbance estimates. However, these ideal configurations are not always available or achievable. Because the noise level in the SINS/DGPS gravimetric system generally decreases with an increase of speed and altitude of the platform, the stringent constraints on the IMU and GPS may be relieved in the airborne scenario. This paper presents an investigation of one navigation-grade and one tactical-grade IMU for the possibility of low-cost INS/GPS airborne gravimetry. We use the data collected during the Gravity-Lidar Study of 2006 (GLS06), which contains aerogravity, GPS, and INS along the northern coastline of the Gulf of Mexico. The gravity disturbance estimates from the navigation-grade IMU show 0.5–3.2 mGal precision compared with the onboard gravimeter’s measurements and better than 3 mGal precision compared with the upward continued surface control data. Due to relatively large (240 s) smoothing window, the results have about 34 km along-track resolution. But the gravity estimates from the tactical-grade IMU have much poorer precisions. Nonetheless, useful contributions from the tactical-grade IMU could be extracted for longer wavelengths. Numéro de notice : A2011-376 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0462-2 Date de publication en ligne : 26/03/2011 En ligne : https://doi.org/10.1007/s00190-011-0462-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31155 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2011091	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Building agent-based walking models by machine-learning on diverse databases of space-time trajectory samples / Paul M. Torrens in Transactions in GIS, vol 15 supplement s1 (July 2011)  

Permalink

Regional reference network augmented precise point positioning for instantaneous ambiguity resolution / X. Li in Journal of geodesy, vol 85 n° 3 (March 2011)  

Permalink

An agent-based model for optimal land allocation (AgentLA) with a contiguity constraint / Y. Chen in International journal of geographical information science IJGIS, vol 24 n°7-8 (july 2010)  

Permalink

Feature-based cartographic modelling / K. French in International journal of geographical information science IJGIS, vol 24 n°1-2 (january 2010)  

Permalink

A matching algorithm for detecting land use changes using case-based reasoning / X. Li in Photogrammetric Engineering & Remote Sensing, PERS, vol 75 n° 11 (November 2009)  

Permalink

Ant intelligence for solving optimal path-covering problems with multi-objectives / X. Li in International journal of geographical information science IJGIS, vol 23 n° 7-8 (july 2009)  

Permalink

Intelligent GIS for solving high-dimensional site selection problems using ant colony optimization techniques / X. Li in International journal of geographical information science IJGIS, vol 23 n°3-4 (march - april 2009)  

Permalink

An innovative method to classify remote-sensing images using Ant Colony Optimization / X. Liu in IEEE Transactions on geoscience and remote sensing, vol 46 n° 12 (December 2008)  

Permalink

A bottom-up approach to discover transition rules of cellular automata using ant intelligence / X. Liu in International journal of geographical information science IJGIS, vol 22 n°11-12 (november 2008)  

Permalink

The time wave: a new method of visual exploration of geo-data in timespace / X. Li in Cartographic journal (the), vol 45 n° 3 (August 2008)  

Permalink