Geoscience Reference
In-Depth Information
Maple - a Web Map Service for Verbal
Visualisation using Tag Clouds Generated from
Map Feature Frequencies
Stefan Hahmann, Dirk Burghardt
Dresden University of Technology, Institute for Cartography,
Helmholtzstraße 10, 01069 Dresen, Germany
stefan.hahmann@tu-dresden.de, dirk.burghardt@tu-dresden.de
Abstract
Tag cloud visualisation has been introduced in the seventies. In current
Web 2.0 applications this method is a very popular visualisation technique.
This paper presents an approach that uses this technique in combination
with maps. Our method augments cartographic representations with addi-
tional verbal content, which is one of the strongest instruments available to
cartographers to communicate spatial information. The idea is that only
few words extracted from the semantics contained in the features of the
underlying map are suitable to characterise the map section as a whole. To
demonstrate the approach we used the OpenStreetMap dataset. In order to
allow a variety of web map clients to use the results of the method, we
realised the prototype by implementing it as a Web Map Service (WMS)
based on the according Open Geospatial Consortium (OGC) specification.
1- Introduction: History of Tag Clouds and Related Work
More than 30 years ago, Milgram and Jodelet (1976) introduced the tech-
nique of drawing words at different font sizes to present a visual overview
of a text corpus. The results of their work on a “collective mental map of
Paris” are shown in
Figure 1
. The method they used may be seen as the
origin of “tag cloud visualisation”.
