Negotiation and coordination of activities involving a number of people can be a difficult and time-consuming process, even when all participants are collocated. We propose the use of spatial proximity regions around mobile devices on a table to significantly reduce the effort of proposing and exploring content within a group of collocated people. In order to determine the location of devices on ordinary tables, we developed a tracking mechanism for a camera-projector system that uses dynamic visual markers displayed on the screen of a device. We evaluated our spatial proximity region based approach using a photo-sharing application for people sat around a table. The tabletop provides a frame of reference in which the spatial arrangement of devices signals the coordination state to the users.

The results from the study indicate that the proposed approach facilitates coordination in several ways, for example, by allowing for simultaneous user activity and by reducing the effort required to achieve a common goal. Our approach reduced the task completion time by 43% and was rated as superior in comparison to other established techniques.


Kray, C., Rohs, M., Hook, J., Kratz, S. Bridging the gap between the Kodak and Flickr generations: a novel interaction technique for collocated photo sharing. IJHCS, 67, 12 (2009), Elsevier, 1060-1072. Download

Kray, C., Rohs, M., Hook, J., and Kratz, S. Group Coordination and Negotiation through Spatial Proximity Regions around Mobile Devices on Augmented Tabletops. In Proc. of ITS'08, IEEE, 1-8. Download


Could phones bridge the photo-sharing generation gap? (New Scientist) Read