1.1.2. Simplification and Generalisation

We already mentioned that in the past, there were only paper maps but no screen maps. Today, we have the possibility to visualise a map on the screen. One may think that it is easy to create a screen map namely by simply scanning a quality paper map and putting the resulted digital map on the Internet. But this step would not lead to a quality screen map.

A paper map can be used as template for the creation of a screen map, but it has to undergo major adjustments:

• Distances between map elements and minimum sizes should be chosen larger for screen maps than for paper maps (as you will see in the next chapter).
• The information density should be adapted according to the enlargement of the symbolization.
• (1996) recommends a reduction of the information density by a factor 2 to 3.
• Furthermore, the geometry of map elements must be much more generalized for screen display.
• Particularly, the point density of lines must be reduced as well as text labels have to be adapted respectively.
• Thematic classes may possibly have to be restructured and reduced in number. (Räber et al. 2003)

High point density

Low point density

Information density on paper map (Hallwag Kümmerly + Frey)

Information density on screen map (Brühlmeier 2000)