SVG for adaptive visualisations in mobile situations

Tumasch Reichenbacher
Department of Cartography
Technical University Munich
Arcisstr. 21, D-80333 München
tel: ++49 89 289-22836
fax: ++49 89 280-9573
e-mail: tumasch@bv.tum.de

 

GISs are moving away from a system for experts towards a more widely used tool for answering spatial related questions. The dawn of new technologies on the horizon, such as telecommunication, mobile Internet, and handheld computing devices, offers new chances to the everyday use of geoinformation. Especially Location Based Services – making use of the known mobile device position – are able to provide more valuable information to the user. However, these existing approaches to mobile visualisation of geoinformation mostly have a commercial background and are rather technology centred. This quite narrow view ignores many relevant problems and does not fully profit from the new possibilities a mobile cartography could provide. One major problem are the limited resources in a mobile environment, ranging from low CPU and memory to small screens and low network bandwidth.
Hence, after a brief description of the characteristics of the mobile environment and its building blocks, we will sketch a general conceptual framework for geoinformation use in a mobile environment based on an adaptive approach, since we consider too much interaction between user and device in mobile situations to be a hindrance. Interaction should therefore be limited to bare necessities and, if possible, be replaced by adaptation methods, though interaction should always be enabled.
The focus of this paper will be on adaptive and dynamic generation of visualisations for mobile users on the basis of vector data. By adaptive visualisation we mean the personalisation of the presentation mode in correspondence to the current user as well as the adoption to the device and the current context. Methodologically the adaptation occurs on different levels: content, technology, and presentation form. We will put emphasis on the adaptation of the presentation form and demonstrate how to use SVG for delivering adapted content to mobile users.
Important technical and research questions are discussed such as the dynamic generation of SVG files from database content, depending on user, context, and constraints, as well as the derivation of SVG from geoinformation coded in GML or other XML encoded information. SVG seems well suited for the goal of presenting dynamic and adapted geoinformation content to mobile users, since it offers a lot of useful features for this task. We try to highlight the relevant portions of SVG and touch the ideas of the SVG Mobile specification.
To illustrate the rather theoretical concept, sketched in the first part, we will present some small demo examples showing the possibilities using user models and context models for generating different visualisations from the same information source. This part will show the server side generation of SVG documents depending on the current user category and context type using solutions such as the OpenSVGMapserver.
The examples should also outline some possible adaptation methods in SVG. Adaptations can be achieved  by applying SVG filters, hierarchically structuring SVG documents, and progressively rendering SVG files.