Web-based distribution of GIS metropolitan maps

Much research on spatial data retrieval has been accumulated in the past two decades. However, the research of Internet distribution of GIS contents is still in its infancy. This paper describes a systematic approach to optimize Internet distribution of GIS vector maps. The goal is to reduce user-perceived response time and improve viewers´ navigation efficiency. At the center of this approach is a hierarchical content management model. Each multiple-layer vector map is divided into partitions, or blocks, of a predetermined size to build a hierarchy. This size is chosen so that most compressed blocks can be downloaded reasonably quickly at typical connection speeds. A front-end cache and a novel application-level locality-based pre-fetching method are devised. Experiments with a Java prototype have shown smooth panning and fast zooming when large map data sets are accessed