Areal types

[link to areal types]


The new concept of areal types was developed to overcome the limits of traditional land-use classification methods like the maximum-likelihood approach. Looking on urban structures the planners are dealing with, there is often poor correspondence between the pixel classes directly derived from the satellite and the urban planning units. Problems caused by mixed pixels, image distortions or surface structures representing different forms of land-use with similar electromagnetical properties, could be abolished or minimized to a high degree. This is particularly important for a highly differentiated urban region.

Areal types are complex spatial aggregates, usually consisting of several distinct pixel classes, which contribute to them in characteristic proportions depending on the areal type. Areal types represent physiognomic as well as functional units.

Following our intention to reach a high degree of automation, objectivity and transparency, we designed a rule-based classification scheme dealing with the areal percentages of the satellite-based pixel classes. The areal percentages of each pixel class have been calculated for every single grid element with a resolution of 100m and 25m for the whole test site. The automated classification resulted in 15 areal types. Most of the rural areal types like water or forestial areas could be delineated with simple majority rules for the dominating pixel class of this areal type. Other areal types, especially the ones describing urban, heterogeneous settlement structures necessitated complex rules combining the percentages of several pixel classes with 'AND' or 'OR' conditions.

 

Tab.: Areal Types applied in KABA and their spatial characteristics

No. Code Areal type Spatial characteristics
1 10 Forestial areas
  • Rural, partly urban.
2 20 Grasslands
  • Rural, partly in urban peripheral zones.
3 30 Water areas
  • Urban and rural.
4 40 Areas of arable land
  • Rural, partly in urban peripheral zones.
5 50 Sports fields, parks and urban greens
  • Urban and rural.
6 60 Horticultural areas
  • Urban peripheral zones.
7 70 Extensive railway areas
  • Urban, partly in the center of larger rural towns.
8 80 Low density housing
  • Rural and in urban peripheral zones.
9 90 Settlements of mixed structure
  • Urban and in rural village centers.
10 100 Urban housing
  • Urban.
11 110 Dense urban housing
  • Urban, mainly close to the city center.
12 120 Combined housing and industrial areas
  • Urban, partly in dedicated rural zones.
13 130 Commercial and industrial areas
  • Urban, partly in dedicated rural zones.
14 140 High density urban areas
  • Urban, mainly in the city center.
15 150 Extensive traffic areas
  • Urban and rural.

 

For further, more detailed information you may click on Proceedings, see publication list or contact Dr. Dieter Scherer or Dr. Ute Fehrenbach.


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(Ute.Fehrenbach@unibas.ch)