Abstract
Extremely large data sets are now commonplace, and they are often visualized through the World Wide Web. Scalability of web-based visualization techniques is thus a key issue. This paper investigates the scalability of four representative techniques for dynamic map generation and display (e.g., for visualizing geographic sources of web site hits): generating a single composite map image, overlaying images on an underlying base map and two variants of overlaying HTML on a base map. These four techniques embody a mixture of different display technologies and distribution styles (three server-side and one distributed across both client and server). Each technique was applied to 20 synthetic data sets of increasing size, and the data set volume, elapsed time and memory consumption were measured. The results show that all four techniques are suitable for small data sets comprising a few thousand points, but that the two HTML techniques scale to larger data sets very poorly across all three variables.