Efficient and consistent line simplification for web mapping. (16th January 2007)

• Record Type: Journal Article
• Authors: Bertolotto, Michela; Zhou, Min
• Is Part Of: International journal of Web engineering and technology. Volume 3:Number 2(2007)
• Page Start: 139
• Page End: 156
• Publication Date: 2007-01-16
• Subjects: map generalisation -- multiple map representations -- progressive vector transmission -- line simplification -- web mapping -- GIS -- geographical information systems -- web GIS; World Wide Web -- Periodicals; Web site development -- Periodicals; Application software -- Development -- Periodicals; 006.7
• Languages: English
• ISSNs: 1476-1289

Abstract

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.