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Automatisierung der kartographischen Verdrängung mittels Energieminimierung / Dirk Burghardt (2001)

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Titre :	Automatisierung der kartographischen Verdrängung mittels Energieminimierung
Titre original :	[Automatisation de l'élimination cartographique avec la minimalisation d'énergie]
Type de document :	Thèse/HDR
Auteurs :	Dirk Burghardt, Auteur
Editeur :	Munich : Bayerische Akademie der Wissenschaften
Année de publication :	2001
Collection :	DGK - C
Sous-collection :	Dissertationen num. 536
Importance :	95 p.
Format :	21 x 30 cm
ISBN/ISSN/EAN :	978-3-7696-9575-5
Note générale :	Bibliographie
Langues :	Allemand (ger)
Descripteur :	[Vedettes matières IGN] Bases de données localisées [Termes IGN] calcul variationnel [Termes IGN] cartographie numérique [Termes IGN] conflit d'espace [Termes IGN] déplacement d'objet géographique [Termes IGN] données vectorielles [Termes IGN] factorisation de Cholesky [Termes IGN] fonction spline [Termes IGN] formule d'Euler [Termes IGN] généralisation cartographique automatisée [Termes IGN] objet géographique linéaire [Termes IGN] objet géographique ponctuel [Termes IGN] objet géographique zonal
Résumé :	(Auteur) With the help of highly advanced cartographic software programs it is possible to produce topographic maps from digital data. In some cases, however, there exist graphical conflicts, because symbol widths require more space than their real-size equivalents. Generalization of such objects by manual editing is rather time-consuming. Therefore, automation of generalization operations is desirable and should be possible in the age of information technology. Automated cartographic displacement of vector data distinguishes between point, line and area objects subject to processing. Modeling of line objects assumes a central position, because the human eye is extremely sensitive to shape alterations caused by displacement. In many applications splines are well-known tool for describing lines. It is especially the energy-minimizing spline also called snakes model shape deformation as a result of external forces. The internal energy is used to maintain the line shape which has been displaced due to conflicts. First and second derivatives of the line coordinates with respect to the are length are used as quality measures. In cartographic displacement a minimal distance between adjacent objects should be maintained. The external energy is used to describe the conflict situation if objects are too close to each other. To solve the graphic conflicts while maintaining the shape of the objects, the method of energy minimization is employed. Minimizing the energy functional of internal and external energy leads to two independent Euler equations. These are discretized by means of finite differences. The equations can be solved iteratively using the Cholesky factorization. Parametrization of the energy-minimizing splines by means of the tangent angle function (tafus) replaces the two eulerian equations of the 4th order with one equation of the 2nd order. Simplification of the equation system requires an additional amount of calculation for transforming the resulting changes of line direction to attain cartesian coordinates. Verification of a desirably faster convergence has yet to be achieved. The Greedy Algorithm is an alternative procedure to accomplish energy minimization using the Variational Calculus. With the aid of this algorithm the energy of each individual support point is minimized by way of minor displacements. As opposed to the Variational Calculus the effects are more local. Therefore, the Greedy Algorithm is advantageous used for the displacement of buildings or for the positioning of label boxes. The integration of this displacement approach in a cartographic program provides evidence of the fact that it can be used in practical applications. Cooperation with a software producer will help to find additional fields of application, a case in point being the automated map edge work which allows displacement and suppression of text and symbols at the map boundaries. Experience has shown that the research effort required for developing new software tools is estimated to amount to between 30 and 50 percent of the total effort.
Numéro de notice :	27829
Affiliation des auteurs :	non IGN
Thématique :	GEOMATIQUE/INFORMATIQUE
Nature :	Thèse étrangère
Permalink :	https://documentation.ensg.eu/index.php?lvl=notice_display&id=56453

Exemplaires(2)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
27829-02	37.10	Livre	Centre de documentation	Géomatique	Disponible
27829-01	37.10	Livre	Centre de documentation	Géomatique	Disponible

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