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Multiresolution compression and visualization of global topographic data / T. Gerstner in Geoinformatica, vol 7 n° 1 (March - May 2003)  

Public [article]  inGeoinformatica > vol 7 n° 1 (March - May 2003) . - pp 7 - 32 Titre : Multiresolution compression and visualization of global topographic data Type de document : Article/Communication Auteurs : T. Gerstner, Auteur Année de publication : 2003 Article en page(s) : pp 7 - 32 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie numérique [Termes IGN] arbre-B [Termes IGN] compression de données [Termes IGN] données topographiques [Termes IGN] modèle numérique de terrain [Termes IGN] représentation multiple [Termes IGN] Triangulated Irregular Network [Termes IGN] visualisation Résumé : (Auteur) We present a multiresolution model for terrain surfaces which is able to handle large-scale global topographic. It is based on a hierarchical decomposition of the sphere by a recursive bisection triangulation in geographic coordinates. Error indicators allow the representation of the data at various levels of detail and enable data compression by local omission of data values. The resulting adaptive hierarchical triangulation is stored using a bit code of the underlying binary tree and additionally, relative pointers which allow a selective tree traversal. This way, it is possible to work directly on the compressed data. We show that significant compression rates can be obtained already for small threshold values. In a visualization application, adaptive triangulations which consist of hundreds of thousands of shaded triangles are extracted and drawn at interactive rates. Numéro de notice : A2003-059 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1023/A:1022818126783 En ligne : https://doi.org/10.1023/A:1022818126783 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22355 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-03011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Ordering points for incremental TIN construction from DEMs / J.J. Little in Geoinformatica, vol 7 n° 1 (March - May 2003)  

Public [article]  inGeoinformatica > vol 7 n° 1 (March - May 2003) . - pp 33 - 53 Titre : Ordering points for incremental TIN construction from DEMs Type de document : Article/Communication Auteurs : J.J. Little, Auteur ; P. Shi, Auteur Année de publication : 2003 Article en page(s) : pp 33 - 53 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Cartographie numérique [Termes IGN] erreur absolue [Termes IGN] erreur aléatoire [Termes IGN] erreur moyenne quadratique [Termes IGN] ligne de base [Termes IGN] modèle numérique de terrain [Termes IGN] Triangulated Irregular Network Résumé : (Auteur) The standard method of building compact triangulated surface approximations to terrain surfaces (TINs) from dense digital elevation models (DEMs) adds points to an initial sparse triangulation or removes points from a dense initial mesh. Typically, in each triangle in the current TIN, the worst fitting point, in terms of vertical distance, is selected. The order of insertion of the points is determined by the magnitude of the maximum vertical difference. This measure produces triangulations that minimize the maximum vertical distance between the TIN and the source DEM. Other approximation criteria are often used, however, including the rootmeansquared error or the mean absolute error, both for the vertical difference and normal difference, i.e., the distance in the direction of the normal to the triangular approximation. For these approximation criteria, we still select the worst fit point, but determine the insertion order by various sums of' errors over the triangle. Experiments show that using these better evaluation measures significantly reduces the size of the TIN for a given approximation error. Numéro de notice : A2003-060 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1023/A:1022870110853 En ligne : https://doi.org/10.1023/A:1022870110853 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22356 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-03011	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Interpretive tools for 3-d structural geological modelling part 1: Bézier-based curves, ribbons and grip frames / E.A. DE Kemp in Geoinformatica, vol 7 n° 1 (March - May 2003)  

Public [article]  inGeoinformatica > vol 7 n° 1 (March - May 2003) . - pp 55 - 71 Titre : Interpretive tools for 3-d structural geological modelling part 1: Bézier-based curves, ribbons and grip frames Type de document : Article/Communication Auteurs : E.A. DE Kemp, Auteur ; K.B. Sprague, Auteur Année de publication : 2003 Article en page(s) : pp 55 - 71 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique [Termes IGN] carte géologique [Termes IGN] géologie structurale [Termes IGN] modélisation 3D [Termes IGN] outil informatique [Termes IGN] système d'information géographique [Termes IGN] visualisation 3D Résumé : (Auteur) Interpreting the geometry of geological objects is a standard activity of fieldbased geologists. We present new Graphics tools that will aid in extending this activity from 2D geological mapping into a 3D environment. Much of the existing 3D geological modeling software supports the construction of objects with the input of dense control data. However, for regional mapping and near mine exploration work, sparse data is the norm. Tools are required therefore, which give the expert interpreter full control of the graphics objects, while at the same time constraining interpretations to specific control data from field observations. We present the initial results of a software design and programming project for the visualization of complex regional scale geologic objects using Bezierbased graphics tools that are optimized for sparse data interpretation. We also introduce the concept of a structural ribbon, which is a 3D extended map trace, along with methods for the optimization of surface construction using graphical grip frames. Numéro de notice : A2003-061 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1023/A:1022822227691 En ligne : https://doi.org/10.1023/A:1022822227691 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22357 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
057-03011	RAB	Revue	Centre de documentation	En réserve L003	Disponible