Abstract. In this paper we describe a new method and user interface for interactive positioning of a mobile device. The key element of this method is a questionanswer style dialogue between system and user about the visibility of nearby objects and landmarks; answers given by the user provide clues about the relative position of the user and allow the verification or falsification of hypotheses about the user’s absolute location. This new approach combines the respective strengths of a human user (i. e. fast and reliable object recognition) and a mobile system (i. e. fast computation of numerical data). It enables accurate positioning without requiring any other positioning technologies. A particular advantage of this approach is that it lends itself to the implementation on camera-equipped mobile phones, where it can be used to increase the accuracy of cell-based localisation methods. 1 Motivation Location-based services (e. g. electronic tour guides [1], location-aware shopping a...