Web-based Spatio-Temporal Presentation and Analysis of Thematic Maps

Map-based visualization and analysis will become an important factor in future Web-applications. Regional location atlases and logistics support are prominent examples. Location-based services will likely become a killer application of next generation mobile phone computers using, e.g., UMTS technology. In the paper we introduce our Descartes system as an interactive, direct manipulation Web-Map software. Descartes is specifically designed to support thematic mapping by automatically proposing alternative visualizations of geo-referenced statistical variables and by providing many functions for analysis. By examples, the paper sketches some of the newer functions built for mapping of spatio-temporal data. Résumé (in French) Not to be written by us. Hans Voss, Natalia Andrienko, Gennady Andrienko, Peter Gatalsky German National Research Institute for Information Technology GMD D-53754 Schloss Birlinghoven Fax:+49 2241 142889 e-mail: [email protected] Why Web-based map presentation and analysis? Governments of cities and regions have many reasons to utilize Geographical Information Systems (GIS). Besides to classical applications for land registers, planning or traffic management, which are mainly used inside of or between departments of one organization, there are new applications that also address people, organizations and companies outside of the organization. The medium making this possible is the Internet. The current paper shall convey new technologies for presenting geographical, spatio-temporal data through the Internet, and make them interactively analyzable by cartographic experts as well as lay persons inand outside of the issuing organization. Although the tools thus provided can also be run on local computers the paper focuses on their use in the Internet because it most clearly demonstrates chances and potential of innovative GIS applications. One prominent such application is the digital location atlas. It may address private persons looking for a new home when moving to a city or region or industrial and service companies when looking for a new location for production, central facilities, service or warehouse center. Site constraints and potential are of increasing importance for most types of enterprises. An intensive and qualified evaluation of many hard and soft factors is most essential in view of an increasing national and international competition in the global age, where the relocation to distant but cheaper places is often not a big stumbling-block any more. From an environmental perspective one has to make up the ecological balance related to the location decision as has become law in many countries, e.g. the German UVP (Umweltverträglichkeitsprüfung evaluation of environmental compatibility). All in all, the right location selection is one of the most important entrepreneurial decisions inducing long-term effects on internal logistics and overall cost structures. Vice versa, a city or region as a potential location is most interested to "market" what it has to offer in order to lure enterprises to settle in its fiscal sphere. Cities and communes, but increasingly regions or pools of cities and communes, have always invested huge resources for (co-operative) public relations. They provide location atlases to the information seeker, and comfortable conditions regarding taxes, land or employees to those interested. Ever more and increasingly attractive presentations are nowadays published in the Internet. The presentation not being "in" may perhaps imply to be "out" as a candidate. This paper shall demonstrate that a powerful technology is available that allows ordinary people to view and analyze maps through the Internet. In particular, we will illustrate by example how our software Descartes can be used for this purpose. Descartes can be used as a general Web mapping tool, but is specially designed to support the automatic mapping of geo-referenced statistical data. The user interface of Descartes the Web client is a Java applet. The rationale is that we want to provide as much direct interactivity for the user as possible. It is not possible to survey all available features and visualization methods of Descartes in the present paper. We will instead focus on some new techniques that were invented to support the analysis of spatio-temporal data. In the rest of the paper we will first assess relevant currently available research results and technology. We will then introduce specific concepts of Descartes by working through an example. The scenario is that someone, say a person given the task of looking for a location of a new service center, analyzes the financial situation of people living in the candidate districts of a prospective city. We further narrow the scenario by taking "family income" as the considered attribute and the City of Helsinki as the city.