Non-Photorealistic Computer Graphics Library

Visualizing Route Maps

Author(s): Maneesh Agrawala.
PhD Thesis: Stanford University, 2002.
[BibTeX]

Abstract:
Route maps, which depict a path from one location to another, can be powerful tools for visualizing and communicating directions. Although creating a route map may seem to be a straightforward task, the underlying design of most route maps is quite complex. Mapmakers choose which information is most essential for following the route and they use a variety of cartographic generalization techniques including distortion, simplication, and abstraction to emphasize this essential information Recently, route maps in the form of driving directions, have emerged as one of the most popular applications on the Web. In contrast to hand-designed route maps, these computer-generated route maps are more precise and contain more informa- tion. Yet, in general, they are also more diFcult and frustrating to use. The main shortcoming of current route map rendering systems is that they do not distinguish between essential and extraneous information. As a result, these systems cannot apply the generalization techniques used in hand-designed maps to emphasize the information needed to follow the route. In this dissertation we present a new set of techniques and algorithms for au- tomatically designing and rendering route maps that are far easier to follow than standard computer-generated route maps. We begin by examining research in cogni- tive psychology and cartography, onhow people think about and communicate routes. Based on this analysis we identify the essential information a route map must com- municate to support navigation. We then examine a variety of hand-designed route maps and enumerate a new set of cartographic generalization techniques specically designed to improve the usability of route maps by emphasizing the most essential route information. Finally, we describe algorithmic implementations of these generalization tech- niques within LineDrive, a real-time system for automatically designing and rendering route maps. LineDrive designs routes maps to the constraints of the display device and can produce clear, easy-to-read maps for a variety of display devices including standard sized web pages, handheld personal digital assistants and WAP cell phones. LineDrive is publicly accessible at www.mapblast.com and we present feedback from over 2200 users of the LineDrive system. The feedback shows that just over 99 percent of users believe LineDrive maps are preferable to using standard computer-generated route maps alone. The response strongly suggests that LineDrive route maps support navigation tasks much better than the standard computer-generated route maps.