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1.4.9. Summary

Thematic data representation and classification

We distinguish between qualitative and quantitative maps. Quantitative maps can be visualised with various representation types:

  • Continuous Representation of data amounts
  • Representation with value intervals
  • Representation with diagrams

A representation with intervals leads to a loss of detail because the exact numerical data relations are not visible anymore. But there are also reasons why a representation with intervals is preferred:

"Unclassed mapped data present a geographical pattern that is not particularly revealing and has little interpretive power. As the data are grouped into similar classes having identical numerical characteristics, there is an increase in their ability to convey information about which generalizations can be made." (Dent 1999)


Like topographic data thematic data can be generalised. We differentiate between five methods:

  • Generalisation of the reference areas
  • Merging diagrams
  • Using signatures of too small diagrams
  • Merging thematic subfields
  • Redistribution of too small partial quantities



Choose the colours for a thematic map carefully! 5-7 colour classes are recommended


Within the topic of interactive thematic maps we are able to combine several of the represenation methods that we listed above. The next example contains some of these functions:

Example of an     interactive thematic mapExample of an interactive thematic map (Neumann 2003)

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