Implicit Virtual Constraints on Tabletops

We present the factors that influence the design of implicit virtual constraints in digital tabletops. Implicit virtual constraints, such as pointer warping and virtual force fields, have been used to improve interaction in desktop applications by manipulating the decoupled link between motor space (mouse motion) and visual space (pointer). The use of virtual constraints in tabletop systems poses unique challenges that arise from the direct coupling of motor space with visual space. In this paper we describe how differences in the type of constraint, either proactive or reactive, as well as the type of input mechanism, may affect the design of implicit virtual constraints in tabletop interaction.