Generalisation Algorithms

Over the past 25 years, automating map generalisation has seen major improvements. Generalisation algorithms constitute the building blocks of the automation process. Generalisation algorithms are more common with individual types of objects such as lines or polygons. Generalisation of the map as a whole is normally conducted manually.

Several algorithms are used for generalisation. The most typical are classified as following:

• Algorithms for simplification: They include the independent point algorithms, e.g. the random selection of points, as well as the local processing algorithms, and global routines. The Douglas-Peucker (Douglas-Peucker, 1973) is the most representative of this class.
• Enhancement algorithms: They include the exaggeration process and the smoothing process.
• Collapsing algorithms: This operation is mainly used for broad rivers because they are usually digitized by their bank lines, but needs to be reduced to a centre line.

To find more information about algorithms used in generalisation, you can have a look on the following project from the University of Zurich: Agent_Esprit.pdf (493 Ko)