A digital tabletop offers several advantages over other groupware form factors for collaborative applications. However, users of a tabletop system do not share a common perspective for the display of information: what is presented right-side-up to one participant is upside- down for another. In this paper, we survey five different rotation and translation techniques for objects displayed on a direct-touch digital tabletop display. We analyze their suitability for interactive tabletops in light of their respective input and output degrees of freedom, as well as the precision and completeness provided by each. We describe various tradeoffs that arise when considering which, when and where each of these techniques might be most useful.
