Tobias Dahinden, Stefan Raeber
Institute of Cartography, ETH Zurich
ETH Hoenggerberg, CH-8093 Zurich
phone: ++41-1-6333037, fax: ++41-1-6331153
If a user has a choice between two maps he/she will often use the map with the 'better' design. This means a map, besides being readable, should be visually attractive, comparable with other maps and eventually deliver some tools to navigate and interact with a map. A further problem is that a lot of maps are not always self-explaining by default. SVG offers some possibility to make maps well designed.
The readability is dependent on several factors: e g. the chosen colors, used fonts or minimal dimensions for symbols, line-styles and fill-patterns. Not all fonts, linestyles and fill-patterns are equally suitable for both screen-maps and printed versions. Maps in SVG are most often primarily prepared for screen use. The reading distance between a monitor and a printed map is different - this means that map-designers should use output dependent minimal dimensions. You have also the possibility to zoom. In this context the level of detail is of great interest. The density of information has to correlate with the scale (this is called 'adaptive zooming'). With SVG's scripting capabilities one can use tricks to show symbols and fonts scale-dependent.
To make maps comparable one has to carefully choose the data source and classification method, besides combining only reasonable subjects. Ideally one can link two or more maps with related datasets in order to better compare and analyze changes and correlations. SVG helps a lot in designing interactive maps, most notably the event model, scripting and smil-animation capabilities. Interactive Maps are a major advantage of screen-maps and the key to map-analysis and query functionality. However, it is not always obvious to the map user how the interactivity works. A clear navigation and usability concept together with tooltips and a comprehensive help-system can assist users in exploring interactive maps. Too much interactivity and obtrusive animations, however, can bother map users and may rather confuse him than assisting in information retrieval.
Map legends are a must in tradtitional printed maps. With interactive maps, legends can be linked to selected map graphics and assist the user in changing symbology and styles. A navigation help is useful but not always necessary. Navigation often means that one has to make a second small-scale linked overview map with a new symbolisation. A few tricks may help to produce them more efficiently and reduce file-sizes by referencing geometry in the main map.
Besides pointing to basic principles for designing visually attractive maps the presentation will often compare examples of good and bad maps created with SVG and show how one can improve inferior map designs.
Literature: Jenny, B., Raeber, S. (2001): Attraktive Webkarten - ein Plaedoyer fuer gute Kartengraphik. In: Symposium Web.Mapping.2001, Karlsruhe.
About the authors:
Tobias Dahinden studied geodesy. Currently he's a PHD student at the Institute of Cartography of the Swiss Federal Institute of Technology. He is working
with SVG since spring 2000. He is also part of the conference organization committee.
Stefan Raeber apprenticed cartography. He works at the Institute of Cartography of the Swiss Federal Institute of Technology as cartographer and webmaster. He has a feeling for visually attractive maps and good map-design in his blood :-) ...