Maps are the most important medium for presenting navigational information to drivers. Quality of maps, presented to their users, has a direct impact on the usability and performance of a car navigation system. In this regard, displaying maps adapted to user's environment and their condition is critical. Users in different context need maps with various scales -zoom level and level of details- to fulfill their information requirements. Since, using a car navigation system is not elementary task for drivers, selecting and presenting maps with proper zoom levels and level of details must be performed by the system intelligently and automatically. In this paper, we offer a method to select the two mentioned factors automatically to present legible maps in different context. Values of these two factors are depending on user's context, so context aware computing has been used in the proposed method. Context aware computing is a computing that enables systems to acquire current user’s context and adapt its behavior accordingly. In this research, various contexts that may have an impact on map scale are studied and then an approach to select proper scale in such contexts is proposed. In addition, based on context aware computing concept an adaptation model is offered that enables system to determine proper map scale in different context. As a proof of the idea, a prototype car navigation system- with the ability of displaying maps in appropriate scales with different context- is implemented and tested in parts of Tehran.
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