Topologically-Consistent Map Generalisation Procedures and Multi-scale Spatial Databases

An important requirement of multiscale spatial databases is that topological consistency is maintained both within individual features and between co-displayed features for all scales at which they may be retrieved. Here we show how a triangulation-based branch-pruning generalisation procedure can be enhanced to enable its output to be used to build topologically-consistent multiscale data structures. A major limitation of existing branch-pruning methods, of the lack of vertex filtering, is overcome by the application of a topologically consistent, vertex priority labelling procedure. The branch pruning generalisation method is also improved by the introduction of an edge re-sampling technique and the provision of control over single and double-sided application of pruning. Experimental results of the use of the techniques are presented.