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An Optimisation Approach to Cartographic Generalisation

Författare:
Publiceringsår: 2001
Språk: Engelska
Sidor:
Dokumenttyp: Doktorsavhandling
Förlag: Department of Technology and Society, Lund University

Sammanfattning

Popular Abstract in Swedish

Idag lagras allt fler kartor digitalt och nya metoder krävs för att förbättra denna digitala hantering. Ett område som studerats under senare tid är automatiska metoder för kartografisk generalisering. Kartografisk generalisering innebär att man förenklar informationen i en karta för att göra den mer lättläst i den önskade skalan. Denna avhandling beskriver en optimeringsmetod för kartografisk generalisering.
Cartographic generalisation is the process of simplifying a representation to suit the scale and purpose of a map. As such, generalisation has always been a central part in map production. This thesis is a contribution to the ongoing work on automating cartographic generalisation. Two topics are treated: optimisation methods in graphic generalisation, and propagation of updates between cartographic data sets of different scales. To enable an optimisation approach to graphic generalisation several topics are studied. Firstly, requirements are stated for defining a good map. These requirements can act as constraints and control the graphic generalisation process. In this thesis, ten analytical constraints for graphic generalisation are proposed, some for single objects and some for groups of objects. Rules are also established regarding when these constraints should be set up. Secondly, the least-squares method is studied as an approach to finding the optimal solution according to the constraints. Related to this, weighting strategies for the constraints are also discussed. Thirdly, computationally efficient methods are tested, which are especially important for establishing spatial relationships between objects and solving the large normal equation systems. Finally, the optimisation approach has been evaluated visually and quantitatively in mid-scale applications. Mapping organisations have to maintain cartographic data sets of different scales (resolutions). Ideally, mapping organisations should only be concerned with updating the most detailed data set and the updates should automatically be propagated to all other data sets. In this study, a prototype system was created for automatic propagation of updates. This system is integrated in an object-oriented map production software, in which the data sets are stored in a multiple representation database. The rules implemented in the prototype system were gathered from data set specifications and by studying printed map series. The propagation of updates performed by the prototype system was compared with manual propagation performed by a cartographer.

Disputation

2001-03-23
10:15
V:B, V-building, John Ericssons väg 1
  • Christopher Jones (Prof)

Nyckelord

  • Civil Engineering
  • incremental generalisation
  • multiple representation
  • least-squares method
  • optimisation
  • cartographic constraints
  • displacement
  • cartographic generalisation
  • graphic generalisation
  • map production
  • object-oriented spatial databases
  • Physical geography
  • geomorphology
  • pedology
  • cartography
  • climatology
  • Fysisk geografi
  • geomorfologi
  • marklära
  • kartografi
  • klimatologi
  • Technological sciences
  • Teknik

Övriga

Published
  • ISSN: 1403-7726
  • ISBN: 91-628-4652-3
  • ISRN: LUTVDG/(TVLM-1002-204)/2001

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