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Novel shape indices for vector landscape pattern analysis / C. Zhang in International journal of geographical information science IJGIS, vol 30 n° 11-12 (November - December 2016)  

Public [article]  inInternational journal of geographical information science IJGIS > vol 30 n° 11-12 (November - December 2016) . - pp 2442 - 2461 Titre : Novel shape indices for vector landscape pattern analysis Type de document : Article/Communication Auteurs : C. Zhang, Auteur ; Peter M. Atkinson, Auteur Année de publication : 2016 Article en page(s) : pp 2442 - 2461 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale [Termes IGN] analyse de données [Termes IGN] anisotropie [Termes IGN] données vectorielles [Termes IGN] indice de détection [Termes IGN] interprétation automatique [Termes IGN] rectangle englobant minimum [Termes IGN] représentation des données [Termes IGN] traitement automatique de données Résumé : (Auteur) The formation of an anisotropic landscape is influenced by natural and/or human processes, which can then be inferred on the basis of geometric indices. In this study, two minimal bounding rectangles in consideration of the principles of mechanics (i.e. minimal width bounding (MWB) box and moment bounding (MB) box) were introduced. Based on these boxes, four novel shape indices, namely MBLW (the length-to-width ratio of MB box), PAMBA (area ratio between patch and MB box), PPMBP (perimeter ratio between patch and MB box) and ODI (orientation difference index between MB and MWB boxes), were introduced to capture multiple aspects of landscape features including patch elongation, patch compactness, patch roughness and patch symmetry. Landscape pattern was, thus, quantified by considering both patch directionality and patch shape simultaneously, which is especially suitable for anisotropic landscape analysis. The effectiveness of the new indices were tested with real landscape data consisting of three kinds of saline soil patches (i.e. the elongated shaped slightly saline soil class, the circular or half-moon shaped moderately saline soil, and the large and complex severely saline soil patches). The resulting classification was found to be more accurate and robust than that based on traditional shape complexity indices. Numéro de notice : A2016-757 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2016.1179313 En ligne : http://dx.doi.org/10.1080/13658816.2016.1179313 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82422 [article]

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Building detection in complex scenes thorough effective separation of buildings from trees / M. Awrangjeb in Photogrammetric Engineering & Remote Sensing, PERS, vol 78 n° 7 (July 2012)    

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 78 n° 7 (July 2012) . - pp 729 - 745 Titre : Building detection in complex scenes thorough effective separation of buildings from trees Type de document : Article/Communication Auteurs : M. Awrangjeb, Auteur ; C. Zhang, Auteur ; Clive Simpson Fraser, Auteur Année de publication : 2012 Article en page(s) : pp 729 - 745 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] détection automatique [Termes IGN] détection du bâti [Termes IGN] données lidar [Termes IGN] extraction de la végétation [Termes IGN] image aérienne Résumé : (Auteur) Effective separation of buildings from trees is a major challenge in image-based automatic building detection. This paper presents a three-step method for effective separation of buildings from trees using aerial imagery and lidar data. First, it uses cues such as height to remove objects of low height such as bushes, and width to exclude trees with small horizontal coverage. The height threshold is also used to generate a ground mask where buildings are found to be more separable than in so-called normalized DSM. Second, image entropy and color information are jointly applied to remove easily distinguishable trees. Finally, an innovative rule-based procedure is employed using the edge orientation histogram from the imagery to eliminate false positive candidates. The improved building detection algorithm has been tested on different test areas and it is shown that the algorithm offers high building detection rate in complex scenes which are hilly and densely vegetated. Numéro de notice : A2012-323 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.14358/PERS.78.7.729 En ligne : https://doi.org/10.14358/PERS.78.7.729 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31769 [article]

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Building detection in complex thorough effective separation of buildings from trees / M. Awrangjeb in Photogrammetric Engineering & Remote Sensing, PERS, vol 78 n° 7 (July 2012)  

Public [article]  inPhotogrammetric Engineering & Remote Sensing, PERS > vol 78 n° 7 (July 2012) . - pp 729 - 745 Titre : Building detection in complex thorough effective separation of buildings from trees Type de document : Article/Communication Auteurs : M. Awrangjeb, Auteur ; C. Zhang, Auteur ; Clive Simpson Fraser, Auteur Année de publication : 2012 Article en page(s) : pp 729 - 745 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] arbre (flore) [Termes IGN] détection de contours [Termes IGN] détection du bâti [Termes IGN] données lidar [Termes IGN] histogramme [Termes IGN] image aérienne [Termes IGN] modèle numérique de surface [Termes IGN] seuillage d'image Résumé : (Auteur) Effective separation of buildings from trees is a major challenge in image-based automatic building detection. This paper presents a three-step method for effective separation of buildings from trees using aerial imagery and lidar data. First, it uses cues such as height to remove objects of low height such as bushes, and width to exclude trees with small horizontal coverage. The height threshold is also used to generate a ground mask where buildings are found to be more separable than in so-called normalized DSM. Second, image entropy and color information are jointly applied to remove easily distinguishable trees. Finally, an innovative rule-based procedure is employed using the edge orientation histogram from the imagery to eliminate false positive candidates. The improved building detection algorithm has been tested on different test areas and it is shown that the algorithm offers high building detection rate in complex scenes which are hilly and densely vegetated. Numéro de notice : A2012-359 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14358/PERS.78.7.729 En ligne : http://dx.doi.org/10.14358/PERS.78.7.729 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31805 [article]

Georeferencing performance of THEOS satellite imagery / S. Liu in Photogrammetric record, vol 26 n° 134 (June - August 2011)  

Public [article]  inPhotogrammetric record > vol 26 n° 134 (June - August 2011) . - pp 250 - 262 Titre : Georeferencing performance of THEOS satellite imagery Type de document : Article/Communication Auteurs : S. Liu, Auteur ; Clive Simpson Fraser, Auteur ; C. Zhang, Auteur ; et al., Auteur Année de publication : 2011 Article en page(s) : pp 250 - 262 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s) [Termes IGN] géoréférencement direct [Termes IGN] image à très haute résolution [Termes IGN] image Theos [Termes IGN] ligne de visée [Termes IGN] Melbourne [Termes IGN] modèle géométrique de prise de vue [Termes IGN] orientation du capteur [Termes IGN] point d'appui [Termes IGN] THEOS Résumé : (Auteur) This paper reports on the application of a generic physical sensor orientation model for evaluation of the georeferencing performance of 2 m resolution imagery from the Thailand Earth Observation System (THEOS) satellite. Within the generic sensor orientation model, orbit and attitude data are employed to describe the satellite trajectory, which is further modelled by splines. The satellite orbit and sensor attitude errors are then compensated via sensor orientation adjustment using a modest number of ground control points (GCPs), resulting in improved georeferencing. The generic sensor model and the integration of the THEOS orientation parameters into the model are first described. The presence of errors in the satellite line-of-sight data, which result in imprecise sensor interior orientation are then discussed. Such errors can be effectively accounted for through modelling via a cubic polynomial, leading to sub-pixel georeferencing accuracy. An account is then given of an experimental evaluation of THEOS georeferencing conducted in a well-established testfield near Melbourne, Australia. The results demonstrate that sub-pixel 2D geopositioning accuracy is readily achievable with single THEOS images and within strips of up to three images, with as few as six GCPs to effect an orbit adjustment. However, accuracy decreases to near the 2-pixel level over a strip length of five images. Numéro de notice : A2011-243 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1111/j.1477-9730.2011.00634.x Date de publication en ligne : 06/06/2011 En ligne : https://doi.org/10.1111/j.1477-9730.2011.00634.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31021 [article]

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106-2011021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Cloaking locations for anonymous location based services: a hybrid approach / C. Zhang in Geoinformatica, vol 13 n° 2 (June 2009)  

Public [article]  inGeoinformatica > vol 13 n° 2 (June 2009) . - pp 159 - 182 Titre : Cloaking locations for anonymous location based services: a hybrid approach Type de document : Article/Communication Auteurs : C. Zhang, Auteur ; Y. Huang, Auteur Année de publication : 2009 Article en page(s) : pp 159 - 182 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes IGN] service fondé sur la position [Termes IGN] téléphonie mobile [Termes IGN] utilisateur nomade Résumé : (Auteur) An important privacy issue in Location Based Services is to hide a user’s identity while still provide quality location based services. Previous work has addressed the problem of locational $\mathcal{K}$-anonymity either based on centralized or decentralized schemes. However, a centralized scheme relies on an anonymizing server (AS) for location cloaking, which may become the performance bottleneck when there are large number of clients. More importantly, holding information in a centralized place is more vulnerable to malicious attacks. A decentralized scheme depends on peer communication to cloak locations and is more scalable. However, it may pose too much computation and communication overhead to the clients. The service fulfillment rate may also be unsatisfied especially when there are not enough peers nearby. This paper proposes a new hybrid framework called HiSC that balances the load between the AS and mobile clients. HiSC partitions the space into base cells and a mobile client claims a surrounding area consisting of base cells. The number of mobile clients in the surrounding cells is kept and updated at both client and AS sides. A mobile client can either request cloaking service from the centralized AS or use a peer-to-peer approach for spatial cloaking based on personalized privacy, response time, and service quality requirements. HiSC can elegantly distribute the work load between the AS and the mobile clients by tuning one system parameter base cell size and two client parameters - surrounding cell size and tolerance count. By integrating salient features of two schemes, HiSC successfully preserves query anonymity and provides more scalable and consistent service. Both the AS and the clients can enjoy much less work load. Additionally, we propose a simple yet effective random range shifting algorithm to prevent possible privacy leakage that would exist in the original P2P approach. Our experiments show that HiSC can elegantly balance the work load based on privacy requirements and client distribution. HiSC provides close to optimal service quality. Meanwhile, it reduces the response time by more than an order of magnitude from both the P2P scheme and the centralized scheme when anonymity level(value of $\mathcal{K}$) or number of clients is large. It also reduces the update message cost of the AS by nearly 6 times and the peer searching message cost of the clients by more than an order of magnitude. Copyright Springer Numéro de notice : A2009-074 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10707-008-0047-2 En ligne : https://doi.org/10.1007/s10707-008-0047-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29704 [article]

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057-09021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

An analysis of urban spatial structure using comprehensive prominence of irregular areas / C. Zhang in International journal of geographical information science IJGIS, vol 22 n° 6-7 (june 2008)  

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Digital surface models from high-resolution satellite imagery / J. Poon in Photogrammetric Engineering & Remote Sensing, PERS, vol 73 n° 11 (November 2007)  

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Automated registration of high-resolution satellite images / C. Zhang in Photogrammetric record, vol 22 n° 117 (March - May 2007)  

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The role of Web features et and Web Map Services in real-time geospatial data sharing for time-critical applications / C. Zhang in Cartography and Geographic Information Science, vol 32 n° 4 (October 2005)  

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Towards an operational system for automated updating of road databases by integration of imagery and geodata / C. Zhang in ISPRS Journal of photogrammetry and remote sensing, vol 58 n° 3-4 (January - June 2004)  

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