Computational geometry: an introduction
Computational geometry: an introduction
On-line construction of the convex hull of a simple polyline
Information Processing Letters
Progressive vector transmission
Proceedings of the 7th ACM international symposium on Advances in geographic information systems
Simplifying a polygonal subdivision while keeping it simple
SCG '01 Proceedings of the seventeenth annual symposium on Computational geometry
Hardware-assisted view-dependent map simplification
SCG '01 Proceedings of the seventeenth annual symposium on Computational geometry
Transmitting Vector Geospatial Data across the Internet
GIScience '02 Proceedings of the Second International Conference on Geographic Information Science
Ontology-driven map generalization
Journal of Visual Languages and Computing
A hybrid aggregation and compression technique for road network databases
Knowledge and Information Systems
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Commercial Geographical Information Systems (GISs) incorporate line simplification functionality to generate generalised versions of maps. A commonly used algorithm is the classical Ramer-Douglas-Peucker (RDP) algorithm. Such an algorithm does not guarantee the preservation of topological consistency and therefore requires a posteriori checks to rectify unwanted intersections. To overcome this problem, Saalfeld proposed a modification based on the fact that, while generalising a polyline, conflicts can only occur with vertices of other polylines that lie within its convex hull. We have developed an improved version of Saalfeld's algorithm to detect possible self-intersections more efficiently. Although this improves the performance, especially when generalising very large data sets, the processing time is still not acceptable for real-time web mapping. Therefore, we have integrated our algorithm into a web-mapping system that relies on progressive transmission. In this paper we describe our improved algorithm and the experimental results. We also discuss the progressive transmission approach.