Toward quantitative measures for the semantic quality of polygon generalization

Map generalization changes the semantics and geometry of map objects according to the context defined by users. How to evaluate and ensure the quality of generalization has become a major issue in contemporary digital cartography. The change in semantics after generalization has been studied much less than the other two aspects (geometry and topology). This research investigates the effect of generalization operations on the semantics of map objects. A set of quantitative measures for semantic change is put forward. A case study of a land-use map is implemented to illustrate the practical usefulness of these proposed measures, with a merging operation as an example of polygon generalization. The results indicate that these measures are not only sound in theory but also meaningful in practice.