2D Touching of 3D Stereoscopic Objects

Recent developments in the area of touch and display technologies have suggested to combine multi-touch systems and stereoscopic visualization. Stereoscopic perception requires each eye to see a slightly different perspective of the same scene, which results in two distinct projections on the display. Thus, if the user wants to select a 3D stereoscopic object in such a setup, the question arises where she would touch the 2D surface to indicate the selection. A user may apply different strategies, for instance touching the midpoint between the two projections, or touching one of them. In this paper we analyze the relation between the 3D positions of stereoscopically rendered objects and the on-surface touch points, where users touch the surface. We performed an experiment in which we determined the positions of the users' touches for objects, which were displayed with positive, negative or zero parallaxes. We found that users tend to touch between the projections for the two eyes with an offset towards the projection for the dominant eye. Our results give implications for the development of future touch-enabled interfaces, which support 3D stereoscopic visualization.