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Multistate supernetwork approach to modelling multi-activity, multimodal trip chains / Theo Arentze in International journal of geographical information science IJGIS, vol 18 n° 7 (november 2004)

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 7 (november 2004) . - pp 631 - 651 Titre : Multistate supernetwork approach to modelling multi-activity, multimodal trip chains Type de document : Article/Communication Auteurs : Theo Arentze, Auteur ; Harry Timmermans, Auteur Année de publication : 2004 Article en page(s) : pp 631 - 651 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes d'information géographique [Termes IGN] analyse coût-avantage [Termes IGN] mobilité urbaine [Termes IGN] réseau de transport [Termes IGN] trajet Résumé : (Auteur) Least-costs path finding methods belong to the standard toolkit of geographical information science and allow one to assign trips with known origin and destination to a transport network. An extension of the network representation is proposed that allows one to model complete trip chains (tours) that may involve multiple transport modes and multiple activities, as a least-cost path through the network. The extension is based on the notion that link costs may change as a consequence of activity and vehicle choices during the tour. The extended network or supernetwork contains as many copies of the network as there are possible activity-vehicle states and additional state transition links to interconnect them. In this way, not only the generalized link cost function, but also the start and end points of a path can be defined state dependently. A leastcost path through a multistate network defines an optimal sequence of travelling, transferring, parking, conducting activities and dropping off products of activities. An application shows how a multistate network can be constructed and used to assess the impacts of network design variables on path choice. Numéro de notice : A2004-625 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/INFORMATIQUE Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26921 [article]

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Examination of a constant-area quadrilateral grid in representation of global digital elevation models / J.T. Bjorke in International journal of geographical information science IJGIS, vol 18 n° 7 (november 2004)

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 7 (november 2004) . - pp 653 - 664 Titre : Examination of a constant-area quadrilateral grid in representation of global digital elevation models Type de document : Article/Communication Auteurs : J.T. Bjorke, Auteur ; S. Nilsen, Auteur Année de publication : 2004 Article en page(s) : pp 653 - 664 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Projections [Termes IGN] arbre quadratique [Termes IGN] calcul d'erreur [Termes IGN] maillage par carrés [Termes IGN] modèle numérique de surface [Termes IGN] ondelette [Termes IGN] quadrant [Termes IGN] tessellation [Termes IGN] World Geodetic System 1984 Résumé : (Auteur) The WGS84 ellipsoid is tessellated using quadrilaterals of roughly the same size. This tiling is of general interest to global geographical information systems, but it has special relevance to global digital elevation models based on block averages. The simple relation between the tiling presented and the latitude/longitude reference system makes the tiling easy to implement, and the quadrilateral property of the cells offers regular subdivision like quadtrees. An error analysis gives a strict bound on the difference between cell averages calculated in plane and ellipsoidal coordinates. The mathematical results from this investigation are general and can be applied in error analysis related to other types of quadrilateral meshes. The grid can be easily subdivided into quadtree blocks. The error estimate makes it possible to combine the quadtree structure with standard two-dimensional wavelet representations. Numéro de notice : A2004-395 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26922 [article]

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Assessing the worldwide developments of national spatial data clearinghouses / Joep Crompvoets in International journal of geographical information science IJGIS, vol 18 n° 7 (november 2004)

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 7 (november 2004) . - pp 665 - 689 Titre : Assessing the worldwide developments of national spatial data clearinghouses Type de document : Article/Communication Auteurs : Joep Crompvoets, Auteur ; A. Bregt, Auteur ; Abbas Rajabifard, Auteur ; I. Williamson, Auteur Année de publication : 2004 Article en page(s) : pp 665 - 689 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données [Termes IGN] catalogue de données localisées [Termes IGN] infrastructure mondiale des données localisées [Termes IGN] INSPIRE [Termes IGN] métadonnées [Termes IGN] serveur de métadonnées [Termes IGN] toile d'araignée mondiale Résumé : (Auteur) Many countries have spent considerable resources over the past few years debating optimal national spatial data infrastructures. One of the (main) elements of these infrastructures is the national spatial data clearinghouse, which facilitates access to required spatial data and provides complementary services. With this in mind, in April 2000, 2001, 2002 and December 2000, 2001, 2002, a web survey was carried out to assess systematically the developments of these national clearinghouses worldwide. Regarding the development in the number of implementations, it can be considered a worldwide success. However, of concern are the declining trends in use, management and content. One of the main reasons for these negative trends could be the dissatisfaction of the spatial data community with the functional capability of current clearinghouses. The functional capabilities of clearinghouses should likely be changed from a data-oriented to a user and application-oriented focus. This is in accord with the objectives of the second generation of spatial data infrastructures. The main factors, therefore, that will have positive impacts on developments in this field are the inclusion of web services, stability of funding and creation of user-friendly interfaces. Numéro de notice : A2004-396 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26923 [article]

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Integrating land-cover data with different ontologies: identifying change from inconsistency / A. Comber in International journal of geographical information science IJGIS, vol 18 n° 7 (november 2004)

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 7 (november 2004) . - pp 691 - 708 Titre : Integrating land-cover data with different ontologies: identifying change from inconsistency Type de document : Article/Communication Auteurs : A. Comber, Auteur ; R. Wadsworth, Auteur ; Peter F. Fisher, Auteur Année de publication : 2004 Article en page(s) : pp 691 - 708 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Infrastructure de données [Termes IGN] analyse comparative [Termes IGN] carte d'occupation du sol [Termes IGN] cohérence des données [Termes IGN] détection de changement [Termes IGN] intégration de données [Termes IGN] jeu de données localisées [Termes IGN] occupation du sol [Termes IGN] ontologie [Termes IGN] Royaume-Uni [Termes IGN] série temporelle Résumé : (Auteur) Spatially coincident land-cover information frequently varies due to technological and political variations. This is especially problematic for timeseries analyses. We present an approach using expert expressions of how the semantics of different datasets relate to integrating temporal time series landcover information where the classification classes have fundamentally changed. We use land-cover mapping in the UK (LCMGB and LCM2000) as example data sets because of the extensive object-based meta-data in the LCM2000. Inconsistencies between the two datasets can arise from random, gross and systematic error and from an actual change in land cover. Locales of possible land-cover change are inferred by comparing characterizations derived from the semantic relations and meta-data. Field visits showed errors of omission to be 21% and errors of commission to be 28%, despite the accuracy limitations of the land-cover information when compared with the field survey component of the Countryside Survey 2000. Numéro de notice : A2004-397 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26924 [article]

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K-guarding of polyhedral terrain / B. Kaucic in International journal of geographical information science IJGIS, vol 18 n° 7 (november 2004)

Public [article]  inInternational journal of geographical information science IJGIS > vol 18 n° 7 (november 2004) . - pp 709 - 718 Titre : K-guarding of polyhedral terrain Type de document : Article/Communication Auteurs : B. Kaucic, Auteur ; B. Zalik, Auteur Année de publication : 2004 Article en page(s) : pp 709 - 718 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG [Termes IGN] méthode heuristique [Termes IGN] polyèdre [Termes IGN] visibilité Résumé : (Auteur) Site visibility analysis is an important research topic with many applications in Geographical Information Systems. This paper introduces a new paradigm in terrain guarding, called k-guarding. K-guarding is a generalization of the classic guarding problem where, instead of only one guard, each surface patch is guarded by at least k guards. Afterwards, two optimization problems based on k-guarding are defined : an optimum k-guarding, and a constrained k-guarding. There are three heuristic approaches - k-greedy add, k-stingy drop, and k-reverse greedy -that are proposed as a solution to the above-mentioned optimization problems. The first two are known approaches adapted to k-guarding, while k-reverse greedy is a new, original heuristic. The heuristics are compared using actual topographic surfaces. It is shown that our approach (k-reverse greedy) gives on average the best near optimum solutions. The most surprising finding of the experiments is that the combination of heuristics introduced here yields even better results. Numéro de notice : A2004-398 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26925 [article]

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