Automating the Generalisation of Geological Maps: Continuous Generalisation

Abstract

The expanding use of digital geological map data is opening up new possibilities for delivering and interacting with geological maps. One such possibility is continuous, or seamless, generalisation, in which the level of generalisation changes in real time as the user zooms in and out of the data. This results in the level of detail shown always being appropriate for the scale at which the data is being viewed and means that only a single large scale database need be maintained.

In this research generalisation algorithms and a viewer application are developed as a demonstration that continuous generalisation can work for geological map data. A two stage process was used in which each feature is given a score showing its relative importance, and then the features to be displayed at a given scale are selected based on their score. The scoring system attempts to mimic a cartographer’s thought process when deciding the relative importance of features by taking the same factors into account. This research concentrates on geological faults and units, but the principles developed here should be applicable to other map layers.

The algorithms and viewer were developed with and tested using 1:10,000 scale data from the Ayr region. The outcome of this research was evaluated by a panel of geoscience professionals from the British Geological Survey. The evaluation is very encouraging and shows that there is much potential in the development of a continuous generalisation tool for use with geological maps.