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Characterisation and generalisation of cartographic lines using Delaunay triangulation / P.M. Van Der Poorten in International journal of geographical information science IJGIS, vol 16 n° 8 (december 2002)
[article]
Titre : Characterisation and generalisation of cartographic lines using Delaunay triangulation Type de document : Article/Communication Auteurs : P.M. Van Der Poorten, Auteur ; Christopher B. Jones, Auteur Année de publication : 2002 Article en page(s) : pp 773 - 794 Langues : Anglais (eng) Descripteur : [Termes IGN] caractérisation
[Termes IGN] cohérence des données
[Termes IGN] généralisation cartographique automatisée
[Termes IGN] objet géographique linéaire
[Termes IGN] squelettisation
[Termes IGN] triangulation de Delaunay
[Vedettes matières IGN] GénéralisationRésumé : (Auteur) A method is presented for generalising cartographic lines using an approach based on determination of their structure. Constrained Delaunay triangulation is used to construct a skeleton of the space surrounding the lines and hence represent line features in terms of skeleton branches. Several statistical measures are used to characterise the triangulation branches. The measures enable selective generalisation of different types of line feature, leading to the possibility of userspecification of the style of generalisation. In our implementation of the approach, the triangulation is updated dynamically to allow both sides of multiple lines to be processed, while guaranteeing topological consistency between the resulting generalised lines. Numéro de notice : A2002-259 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/13658810210149434 En ligne : https://doi.org/10.1080/13658810210149434 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22170
in International journal of geographical information science IJGIS > vol 16 n° 8 (december 2002) . - pp 773 - 794[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 079-02081 RAB Revue Centre de documentation En réserve L003 Disponible Simultaneous graphic generalization of vector data sets / Lars Harrie in Geoinformatica, vol 6 n° 3 (September - November 2002)
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Titre : Simultaneous graphic generalization of vector data sets Type de document : Article/Communication Auteurs : Lars Harrie, Auteur ; Tapani Sarjakoski, Auteur Année de publication : 2002 Article en page(s) : pp 233 - 261 Langues : Anglais (eng) Descripteur : [Termes IGN] C++
[Termes IGN] données vectorielles
[Termes IGN] généralisation automatique de données
[Termes IGN] généralisation cartographique automatisée
[Termes IGN] méthode des moindres carrés
[Termes IGN] méthode du gradient conjugué
[Termes IGN] objet géographique ponctuel
[Termes IGN] optimisation (mathématiques)
[Termes IGN] triangulation de Delaunay
[Vedettes matières IGN] GénéralisationRésumé : (Auteur) Manual cartographic generalization is a simultaneous process. However, most automatic approaches so far have been sequential ; generalization operators are applied one at a time in a certain order. This has been the case both for model generalization (generalization of the conceptual model) and graphic generalization. Our research seeks to demonstrate that the graphic part of cartographic generalization can be formulated as an optimization problem and accordingly be solved in a single step. This paper deals with several issues regarding this optimization approach. Firstly, a set of appropriate analytical constraints for the generalization process is given, as well as rules for when to apply these constraints. In our approach, we are limited to formulating these constraints on point locations. Secondly, leastsquares adjustment is proposed to find the optimal solution according to the constraints. Finally, the conjugate gradients method is recommended for solving the normal equations. A prototype system for simultaneous graphic generalization has been implemented in C++, which communicates with a commercial map production system. Results from three tests of the prototype system are included in the paper. Numéro de notice : A2002-204 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1023/A:1019765902987 En ligne : https://doi.org/10.1023/A:1019765902987 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22119
in Geoinformatica > vol 6 n° 3 (September - November 2002) . - pp 233 - 261[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 057-02031 RAB Revue Centre de documentation En réserve L003 Disponible Preserving cartographic quality in DTM interpolation from contour lines / Gil Rito-Gonçalves in ISPRS Journal of photogrammetry and remote sensing, vol 56 n° 3 (April - June 2002)
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Titre : Preserving cartographic quality in DTM interpolation from contour lines Type de document : Article/Communication Auteurs : Gil Rito-Gonçalves , Auteur ; Patrick Julien , Auteur ; S. Razanioff, Auteur ; Bernard Cervelle, Auteur Année de publication : 2002 Article en page(s) : pp 210 - 220 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image
[Termes IGN] contour
[Termes IGN] courbe de niveau
[Termes IGN] diagramme de Voronoï
[Termes IGN] interpolation
[Termes IGN] modèle numérique de terrain
[Termes IGN] orographie
[Termes IGN] qualité cartographique
[Termes IGN] triangulation de DelaunayRésumé : (Auteur) Fitting an elastic grid to contour lines (CLs) produces a surface with tighter intermediate contours than the initial ones. This leads to intermediate contours that do not match the initial ones. In this paper, we propose a method for correcting this defect, by fitting the elastic grid to supplementary constraint lines that correspond approximately to the terrain morphologic lines (ridges and drainages). We extract these lines from a Delaunay triangulation consistent with the contour lines. We propose a coherent weighting system for the constraints imposed on the elastic grid. Finally, we show that a digital terrain model (DTM) artefact of the type mentioned above can be detected by a simple criterion such as the contour length. Copyright ISPRS Numéro de notice : A2002-095 Affiliation des auteurs : MATIS+Ext (1993-2011) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/S0924-2716(02)00044-8 En ligne : https://doi.org/10.1016/S0924-2716(02)00044-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22010
in ISPRS Journal of photogrammetry and remote sensing > vol 56 n° 3 (April - June 2002) . - pp 210 - 220[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 081-02011 SL Revue Centre de documentation Revues en salle Disponible GPS network monitors the Western Alp's deformation over a five-year period: 1993-1998 / Christophe Vigny in Journal of geodesy, vol 76 n° 2 (February 2002)
[article]
Titre : GPS network monitors the Western Alp's deformation over a five-year period: 1993-1998 Type de document : Article/Communication Auteurs : Christophe Vigny, Auteur ; J. Chery, Auteur ; Thierry Duquesnoy , Auteur ; et al., Auteur Année de publication : 2002 Article en page(s) : pp 63 - 76 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] Alpes occidentales
[Termes IGN] déformation de la croute terrestre
[Termes IGN] montagne
[Termes IGN] positionnement par GPS
[Termes IGN] surveillance géologique
[Termes IGN] tectonique
[Termes IGN] triangulation (topologie)Résumé : (Auteur) The Western Alps are among the best studied collisional belts with both detailed structural mapping and also crustal geophysical investigations such as the ECORS and EGT seismic profile. By contrast, the present-day kinematics of the belt is still largely unknown due to small relative motions and the insufficient accuracy of the triangulation data. As a consequence, several tectonic problems still remain to be Occidental Alps, the repartition of the deformation between the Alpine tectonic units, and the relation between deformation and rotation across the Alpine arc. In order to address these problems, the GPS ALPES group, made up of French, Swiss and Italian research organizations, has achieved the first large-scale GPS surveyed in 1993 and 1998 with a minimum observation of 3 days at each site. GPS data processing has been done by three independent teams using different soft-ware. The different solutions have horizontal repeat-abilities (N-E) of 4-7 min in 1993 and 2-3 mm in 1998 and compare at the 3-5-mm level in position and 2-mm/yr level in velocity. A comparison of 1993 and 1998 coordinates shows that residual velocities of the GPS marks are generally smaller than 2 mm/yr, precluding a detailed tectonic interpretation of the differential motions. However, these data seem to suggest that the N-S compression of the Western Alps is quite mild (less than 2 mm/yr) compared to the global convergence between the African and Eurasian plate (6 mm/yr). This implies that the shortening must be accomodated elsewhere by the deformation of the Maghrebids and/ or by rotations of Mediterranean microplates. Also, EW velocity components analysis supports the idea that E-W extension exists, as already suggested by recent structural and seismotectonic data interpretation Numéro de notice : A2002-018 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-001-0231-8 En ligne : https://doi.org/10.1007/s00190-001-0231-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=21935
in Journal of geodesy > vol 76 n° 2 (February 2002) . - pp 63 - 76[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 266-02021 RAB Revue Centre de documentation En réserve L003 Disponible
Titre : 3D terrain models on the basis of a triangulation Type de document : Thèse/HDR Auteurs : Norbert Pfeifer, Auteur Editeur : Vienne [Autriche] : Technische Universität Wien Année de publication : 2002 Collection : Geowissenschaftliche Mitteilungen, ISSN 1811-8380 num. 65 Importance : 142 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-9500791-7-3 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] données localisées 3D
[Termes IGN] interpolation
[Termes IGN] modèle numérique de terrain
[Termes IGN] noeud
[Termes IGN] reconstruction 3D
[Termes IGN] triangulation de DelaunayRésumé : (Auteur) This work provides an overview on terrain modelling techniques. Terrain models, or in order to be more general, topographic surface models, play an important role in many fields of science and practice where a relation to a location, i.e. a geo-relation' is given. These models describe the height as a function of the location. There lies a restriction in this definition, because only one height is allowed at one ground-plane position. Therefore, the currently used models are often termed 2.5D terrain models. The modelling of overhangs is not possible within such an approach. The aim of this work is to put aside this limitation and provide methods for 3D terrain modelling where not only the above restrictions do not apply anymore, but also more general surfaces with tunnels and cave systems can be reconstructed. Another terrain property which plays an important role in this work is its smoothness: a model shall be smooth. An exception is introduced at so-called breaklines where the terrain shape has a sharp edge.
There are several ways in order to build terrain models with the above characteristics (fully 3D and smooth). In this work, emphasis is put on those approaches which reconstruct the surface on the basis of a triangulation. Two different techniques are treated with great detail: the patch work and the subdivision approach. For each of those two, one method was developed which considers the special requirements in terrain modelling. The main contribution of this work to terrain modelling are those new methods. Generation, improvement, and thinning of triangulations is not treated within this work, but references to the relevant literature are given. Generally, the reconstruction of a patch work proceeds as follows. Given is a triangulation, which has as expected planar faces. For each edge a curve is determined which interpolates the end points. In the next step, triangular patches are inserted into a triple of boundary curves spanned over the edges of each triangle. As the patches interpolate the boundary curve a G0 surface (a geometrically continuous surface) is obtained.
However, this is not enough, because a smooth surface (G1, geometric continuity of order one, i.e. tangent plane continuity) is desired. Adjacent patches must therefore interpolate not only the boundary curves, but also share a common field of cross boundary derivatives. This is the general approach for patch work surfaces.
The patch work method which is proposed in this work1 starts with an enhancement of the triangulation. As the measurement of terrain points and lines is always burdened with random errors (depending on the measurement device characteristics) these errors should be removed first. This can be achieved by kriging, whereby for each point of the triangulation (i.e. each vertex) a filter value is determined from its neighboring points. In this step also the surface normal vectors in the points can be estimated, but alternative methods for the estimation of the normal vector, e.g. by averaging those of the triangles which are incident to that vertex, are possible, too. Now, not only the position, but also the surface normal vector is prescribed for each vertex. The patches which are to be reconstructed over each face of the triangulation shall be polynomials of degree four and they are described with Beziér triangles which allow a geometric interpretation of the coefficients of the (bivariate) polynomial. In the next step, boundary curves of polynomial degree three are computed which replace' the edges of the triangulation. These curves interpolate the end points of the edge and the curve tangents in those points are perpendicular to the estimated normal vectors. This determines the boundaries of each patch. The missing parameters (i.e. coefficients of the polynomial) influence the shape in the interior of the patch and also the tangent planes of the patch along the boundaries. A field of normal vectors is estimated for each boundary curve by blending the normal vectors from the end points into each other. The inner' parameters of a patch are now determined in a way that the normal vector fields are approximately perpendicular to the tangent planes of the patch along the boundaries in a least squares sense. As this field is only' approximated and not interpolated this scheme is called "G1 (i.e. approximately tangent plane continuous).
The second technique for surface reconstruction over a triangulation is the so-called subdivision. In this approach the given triangulation is refined in steps, and in each step new vertices and edges are inserted into the triangulation. This is performed in a way that the smoothness of the triangulation is increased in each level, the angles between adjacent triangles converge towards 180_. The limit surface, reached after an infinite number of subdivision steps, is smooth. An advantage of this approach is that the surface description is always composed of small triangles which allows to apply simple algorithms for intersections and similar tasks. The size of the triangles depends on the number of subdivision steps (i.e. the refinement level). This is the general approach for subdivision surfaces.
Also in the reconstruction technique (developed in this work) for topographic surfaces which is based on subdivision a removal of random measurement errors has to be performed first. The refinement rule applied here is the so-called edge midpoint subdivision where in one step one vertex is inserted into each edge and the triangulation is updated. The subdivision is based on the estimation of local surfaces in each vertex. A local surface is estimated which approximates the vertex of interest and its neighbors. The co-ordinates of the new points are obtained by averaging the two local surfaces in either edge end point. To achieve this, a point, representative for the edge midpoint, is computed on both local surfaces and the mean of these two is the new point. Also the old' points obtain new co-ordinates, namely their position on the local approximating surfaces. Special modifications are introduced in order to interpolate the originally given points. The approaches are compared to each other with examples based on real photogrammetric and geodetic observations as well as on synthetic terrain data. It turns out that the surfaces obtained by the developed subdivision approach meet the requirements in topographic terrain modelling better.Note de contenu : 1 Introduction
2 Modelling of Topographic Surfaces
2.1 Types of Models
2.1.1 Contour lines
2.1.2 Bivariate functions
2.1.3 Volumetric models
2.1.4 Transformation between models
2.2 Global and local approaches
2.3 Models in 2.5D and in 3D
2.4 3D terrain models
2.4.1 Problem definition
3 Algorithms for Triangulations
3.1 Definition of neighborhood
3.2 Parameterization of triangulations
3.2.1 Projection onto a plane
3.2.2 Local projection onto a plane
3.2.3 Global parameterizations
3.2.4 A method for local parameterization
3.3 Surface approximation and estimation of geometric properties
3.3.1 Normal vectors and tangent planes
3.3.2 Approximating quadric as local surface description
3.3.3 Approximating second order polynomial as local surface description
3.4 Functionals and variational principle
3.5 Mesh improvement
3.6 Filtering of random measurement errors
3.7 Consideration of breaklines and special points
3.7.1 Neighborhood restrictions
3.7.2 Prescribed tangent planes
3.7.3 Surfaces and lines at special points
4 Parametric patches
4.1 Patches and patch work
4.2 Method overview
4.3 An "G1-continuous polynomial patch
4.3.1 Approximate continuity
4.3.2 Construction of a curve network
4.3.3 Insertion of patches
4.3.4 Insertion of patches and minimizing energy
4.3.5 Additional splitting
4.3.6 Results
5 Subdivision
5.1 The subdivision paradigm
5.2 Method overview
5.3 Subdivision by estimation of local surfaces
5.3.1 The curve case
5.3.2 Surface subdivision with approximating surfaces
5.3.3 Paraboloids vs. general quadrics as local surfaces
5.3.4 Paraboloids vs. second order polynomials as local surfaces
5.3.5 Interpolation and Approximation
5.3.6 Averaging
5.3.7 Roughness detection
5.3.8 Results
6 Examples
6.1 Vertical Wall
6.2 Data set “Elev”
6.3 Breaklines only
6.4 Data set “Albis”
6.5 Bridge
7 Conclusions and Perspectives
7.1 Applications
7.2 Enclaves
7.3 Concluding remarkNuméro de notice : 14314 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère Note de thèse : PhD : Vermessung und Geoinformation : Technische Universität Wien : 2002 En ligne : https://repositum.tuwien.at/handle/20.500.12708/390?mode=simple Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62656 Analyse de données acquises par laser aéroporté pour la reconstruction 3D de scènes urbaines / R. Elkharroubi (2002)PermalinkExtracting 3D edgels hypotheses from multiple calibrated images : a step towards the reconstruction of curved and straight object boundary lines / Franck Jung (2002)PermalinkGénération, visualisation 3D et exploitation d'un modèle numérique de terrain / I. Koua (2002)PermalinkTIN surface reconstruction from multiple calibrated aerial images in urban areas / Grégoire Maillet (2002)Permalink2.5D-GIS und Geobasisdaten - Integration von Höheninformation und Digitalen Situationsmodellen / U. Lenk (2001)PermalinkCouplage d'un logiciel de trajectographie et du SIG ARC-INFO / I. Koua (2001)PermalinkDigital Elevation Model technologies and applications / D.F. Maune (2001)PermalinkFifth ICA workshop on progress in automated map generalization, August 2 - 4, 2001, Beijing, China / Commission on map generalization ICA (2001)PermalinkMulti-image 3d feature and DSM extraction for change detection and building reconstruction / Nicolas Paparoditis (2001)PermalinkSpatial object aggregation based on data structure, local triangulation and hierarchical analyzing method / Liu Yaolin (2001)PermalinkComparing TIN random densification with the mean profile filter to minimize the ridging phenomenon in service New Brunswick digital terrain models / Kevin H. Pegler in Geomatica, vol 54 n° 4 (December 2000)PermalinkDevelopment of Voronoi-based cellular automata: an integrated dynamic model for Geographical Information Systems / Wenzhong Shi in International journal of geographical information science IJGIS, vol 14 n° 5 (july 2000)PermalinkAlgorithmic foundations of geographic information systems / Marc Van Kreveld (2000)PermalinkEstimation et interpolation spatiale / Michel Arnaud (2000)PermalinkDelaunay triangulations and stereographic projections / A. Saalfeld in Cartography and Geographic Information Science, vol 26 n° 4 (October 1999)PermalinkDelaunay triangulations and stereographic projections / A. Saalfeld in Cartography and Geographic Information Science, vol 26 n° 4 (October 1999)PermalinkSDH 98 Proceedings, 8th international symposium on spatial data handling, Vancouver, July 11 - 15, 1998 / Thomas K. Poiker (1998)PermalinkExploring Geographic Information Systems / Nicholas Chrisman (1997)PermalinkTriangulation de Delaunay et arbres multidimensionnels / Christophe Lemaire (1997)PermalinkTriangulation de Delaunay et maillage / Paul Louis George (1997)Permalink