All across the circle: using auto-ordering to improve object transfer between mobile devices

People frequently form small groups in many social and professional situations: from conference attendees meeting at a coffee break, to siblings gathering at a family barbecue. These ad-hoc gatherings typically form into predictable geometries based on circles or circular arcs (called F-Formations). Because our lives are increasingly stored and represented by data on handheld devices, the desire to be able to share digital objects while in these groupings has increased. Using the relative position in these groups to facilitate file sharing can enable intuitive techniques such as passing or flicking. However, there is no reliable, lightweight, ad-hoc technology for detecting and representing relative locations around a circle. In this paper, we present two systems that can auto-order locations about a circle based on sensors that are standard on commodity smartphones. We tested these systems using an object-passing task in a laboratory environment against unordered and proximity-based systems, and show that our techniques are faster, are more accurate, and are preferred by users.