A context-aware application offering map orientation

University essay from KTH/Kommunikationssystem, CoS


In this thesis context refers to information about the environment (the user or entity's surroundings) that can influence and determine the behavior of a computing system. Context-awareness means that the computer can adapt to the situation in which it is working. Context is a key issue in mobile computing, especially with handheld devices (such as PDAs and mobile phones), due to the fact that they can be used while on the move; hence the environment around them can change. The environment of a static device may also change and require the device to adapt. Applications and systems that exploit context by both sensing and reacting to their environment are called context-aware applications. Devices that are context-aware are able to perceive stimuli and react accordingly, with minimal interaction with the user.

Providing context-aware services to users of mobile devices via context-aware applications is becoming an important and significant factor in the market and is a developing industry. In this thesis we analyze and develop an application that exploits context to provide a service that improves the interaction between humans and a computer. The thesis begins with a study of what types of sensors are available to provide information about the device's context. This is followed by the design of an appropriate way of using the selected sensor (ecompass) to provide a means of adapting a service to the user's and device's context. The focus is every day activities of a student at a university - specifically finding the location of a meeting room for a seminar; however, similar scenarios exist for other types of users.

After determining that it was feasible to add a e-compass as a sensor to an existing personal digital assistant and to provide a map to the mobile user, the focus of the thesis shifted to an examination of the performance of the adaptation of the map as the user moved the device. Initially it required excessive time to render the map on the device, thus as the user moved the device the map was not updated quickly enough for the user to know their correct orientation with respect to the map. Therefore the thesis project examined how this performance could be improved sufficiently that the rendering would keep up with the change in orientation of the device. This investigation lead to a shift from server based rendering of the map as an image, followed by the transfer of the image to the device for display; to a sending a scalable vector graphics version of the map to the device for local rendering. While initially this was expected to be much faster than transferring an image for an actual map of the building where this work was taking place the local rendering was actually slower. This subsequently lead to server based pruning of the irrelevant details from the map, then a transfer of the relevant portion of the map to the device, followed by local rendering.

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