O brother, where art thou located? : Raising awareness of variability in location tracking for users of location-based pervasive applications

Abstract

There is a diversity of ways to determine a user's location in a pervasive environment today. On a large scale, this diversity often results in variability of location tracking conditions throughout the environment. For an important class of pervasive applications, which often rely on the ubiquitous availability of location tracking – location-based pervasive applications, the consistency of their behaviour under this variability cannot be guaranteed. This type of limitation raises a need for the adaptation of the application's behaviour that would reflect this variability. We investigated empirically how visualising different aspects of uncertainty about location and of the behaviour of localisation systems affects users’ impressions about a location-based application. The two components – an ontology that models properties of localisation systems and a set of mapping rules that define how these properties should be visualised in a user interface – are at the core of our approach to providing awareness. The results of the investigation show that the additional visual demand, intended for raising users’ awareness of uncertainty about their location tracking conditions, is perceived to be beneficial by users. We also reveal that different characteristics of this awareness are of different importance to users. Furthermore, we conclude that the particular importance depends on users’ personal profiles (e.g. their eyesight level), on the distance between the users (e.g. knowing about someone else's state is less important if they are far) and on the quality of tracking (the importance increases in problematic areas). On the basis of the obtained results and observations, we suggest a set of guidelines and visualisations, which could be used in designing pervasive applications that require location tracking.