WallTokens: Surface Tangibles for Vertical Displays

Tangibles can enrich interaction with digital surfaces. Among others, they support eyes-free control or increase awareness of other users’ actions. Tangibles have been studied in combination with horizontal surfaces such as tabletops, but not with vertical screens such as wall displays. The obvious obstacle is gravity: tangibles cannot be placed on such surfaces without falling. We present WallTokens, easy-to-fabricate tangibles to interact with a vertical surface. A WallToken is a passive token whose footprint is recognized on a tactile surface. It is equipped with a push-handle that controls a suction cup. This makes it easy for users to switch between sliding the token or attaching it to the wall. We describe how to build such tokens and how to recognize them on a tactile surface. We report on a study showing the benefits of WallTokens for manipulating virtual objects over multi-touch gestures. This project is a step towards enabling tangible interaction in a wall display context.