Fuzzy representation of geographical boundaries in GIS |
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| Authors: | Fangju Wang G Brent Hall |
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| Institution: | 1. Department of Computing and Information Science , University of Guelph , Guelph, Ontario, Canada , N1G 2W1;2. Faculty of Environmental Studies, University of Waterloo , Waterloo, Ontario, Canada , N2L 3G1 |
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| Abstract: | Abstract Polygon boundaries on thematic maps are conventionally considered to be sharp lines representing abrupt changes of phenomena. However, in reality changes of environmental phenomena may also be partial or gradual. Indiscriminate use of sharp lines to represent different types of change creates a problem of boundary inaccuracy. Specifically, in the context of vector-based GIS, use of sharp lines to represent gradual or partial changes may cause misunderstanding of geographical information and reduce analysis accuracy. In this paper, the expressive inadequacy of the conventional vector boundary representation is examined. A more informative technique—the fuzzy representation of geographical boundaries—is proposed, in which boundaries describe not only the location but also the rate of change of environmental phenomena. Four methods of determining fuzzy boundary membership grades from different kinds of geographical data are described. An example of applying the fuzzy boundary technique to data analysis is presented and the advantages of the technique are discussed. |
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