AbstractsComputer Science

With the advent of smartphones and apps, navigation systems have become one of the most widely used mobile applications on the planet. At the same time there are some user groups, especially among people with disabilities, for whom the benefit of navigation systems is even greater than for the average user. Even though navigation systems for those smaller user groups have become available in recent years and are of great help to their users, those navigation systems are currently not as great a tool as they could potentially be, as has been shown by prototypes in smaller research projects. From a user perspective, navigation systems give feedback about the current location, receive input about a desired destination, and guide the user to this destination. In addition to that, the system itself needs to determine the position and calculate a route to the destination. For all of these navigational tasks, the systems needs a world model, be it a map or another representation of the world. Many existing projects have concentrated on adapting these navigational tasks to the specific requirements of a user group, and even though this thesis contributes to these efforts, especially for blind users, its main contribution lies in a different approach. The thesis supposes that the world model provides a great leverage for adapting navigation systems to the specific requirements of the users, as the world model has influence on all navigational tasks and therefore is an integral part of all modern navigation systems. Due to this importance, the world models of currently existing special navigation systems for people with disabilities often suffer from one of two distinct problems: If the model is specifically built for the intended purpose, e.g. a navigation system for a defined disability, it is only available in a confined area. This is mostly the case with research systems. Commercially available systems on the other hand strive to cover as large an area as possible, but have to accept certain drawbacks regarding the world model's applicability for the specific purpose. Ideally, a world model for special navigation systems is both available world-wide and specifically built or at least adapted for the intended purpose. This thesis introduces a way of integrating both requirements. A world model that is widely available and used by many people builds a common base for the navigation system. This ensures the availability and currentness of the data. This world model is then changed individually with Map Content Transformations, which were developed specifically for this purpose. These Map Content Transformations combine data that is implicitly present in the base data with user specific requirements encoded into the transformation rules and thus adapts the world model according to both the requirements of the user and of the intended navigational tasks. It is shown that these adaptations of the world model can have positive influence on all navigational tasks and can, together with the incremental advances regarding the…