Tabletop computers cannot become larger than arm’s length without giving up direct touch. This prevents tabletop applications from dealing with more than a few dozen on-screen objects. We propose direct touch surfaces that are orders of magnitude larger by integrating high-resolution multi-touch into back-projected floors, while maintaining the purpose and interaction concepts of tabletop, i.e., direct manipulation.

We based our design on frustrated total internal reflection because its ability to sense pressure allows the device to see users’ soles when applied to a floor. We demonstrate how this allows us to recognize foot postures and to identify users. These two functions form the basis of our system. They allow the floor to ignore inactive users, identify and track users based on their shoes, enable high-precision interaction, invoke menus, as well as track heads and allow users to control several multiple degrees of freedom by balancing their feet.

Mutitoe is a research project by Caroline Fetzer, Thomas Augsten, Konstantin Kaefer, Dorian Kanitz, Rene Meusel, Thomas Stoff, Christian Holz, Torsten Becker, and Patrick Baudisch at the Human Computer Interaction Lab at Hasso Plattner Institute.