,,Location-based Services“ – Personalisierung mobiler Dienste durch Verortung

Im Zeitalter der Informationsgesellschaft, so wurde postuliert, spielten r?umliche Distanzen keine Rolle mehr und unsere r?umliche Mobilit?t n?hme ab. Die Mobilit?t in den letzten Jahren, speziell die Freizeitmobilit?t, hat hingegen zugenommen. Die Bereitstellung ortsbezogener Dienste – ,,Location-based Services“ – unterstützt und f?rdert dieses Verhalten.     

,,Location-based Services“ – Personalisierung mobiler Dienste durch Verortung

Zusammenfassung Im Zeitalter der Informationsgesellschaft, so wurde postuliert, spielten r?umliche Distanzen keine Rolle mehr und unsere r?umliche Mobilit?t n?hme ab. Die Mobilit?t in den letzten Jahren, speziell die Freizeitmobilit?t, hat hingegen zugenommen. Die Bereitstellung ortsbezogener Dienste – ,,Location-based Services“ – unterstützt und f?rdert dieses Verhalten.     

Ontologies of Wayfinding: a Traveler's Perspective

This paper describes two ontologies of wayfinding with multiple transportation modes in an urban area. One ontology is developed from the perspective of the traveler, which is different from the perspective presented by the public transportation system. Our hypothesis is that the ontology of the traveler is a subset of the ontology of the system, thus leading to the idea of nested ontologies. The ontologies are derived from a case study of wayfinding in the city of Hamburg, Germany. The information on the system's ontology is derived from the material provided to the traveler, e.g., maps, timetables, station layout and signs.     

Multiple representations for cartographic objects in a multi-scale tree—An intelligent graphical zoom

In Geographic Information Systems, a function to draw cartographic sketches quickly and in arbitrary scales is needed. This calls for cartographic generalization, a notoriously difficult problem. Efforts to achieve automatic cartographic generalization were successful for specific aspects, but no complete solution is known, nor are there any expected within the immediate future. In practical applications, a base map is stored and its scale is changed. Without major distortions, only changes to twice or half the original scale are feasible by simple numeric scale change. Everything beyond this requires adaptation of symbols, selection of objects, placements of labels, etc.

Extending ideas of hierarchies or pyramids, where representations of the same objects at different scales are stored, a multi-scale, hierarchial spatial model is proposed. Objects with increasing detail are stored in levels and can be used to compose a map at a particular scale. Applied to the particular problem of cartographic mapping, this results in a multi-scale cartographic tree. The same concept can be used equally well for other applications, which require rendering of objects at different levels of detail.

The structure of the multi-scale tree is explained. It is based on a trade-off between storage and computation, replacing all steps which are difficult to automate by essentially redundant storage. The dominant operation is ‘zoom,’ which moves towards a more detailed level, intelligently replacing the current graphical representation with the more detailed one, appropriate for the selected new scale. Methods to select objects for rendering are based on the principle of equal information density. Principles of possible implementations are presented.