Relative and Absolute Mappings for Rotating Remote 3D Objects on Multi-Touch Tabletops

The use of human fingers as an object selection and manipulation tool has raised significant challenges when interacting with direct-touch tabletop displays. This is particularly an issue when manipulating remote objects in 3D environments as finger presses can obscure objects at a distance that are rendered very small. Techniques to support remote manipulation either provide absolute mappings between finger presses and object transformation or rely on tools that support relative mappings to selected objects. This paper explores techniques to manipulate remote 3D objects on direct-touch tabletops using absolute and relative mapping modes. A user study was conducted to compare absolute and relative mappings in support of a rotation task. Overall results did not show a statistically significant difference between these two mapping modes on both task completion time and the number of touches. However, the absolute mapping mode was found to be less efficient than the relative mapping mode when rotating a small object. Also participants preferred relative mapping for small objects. Four mapping techniques were then compared for perceived ease of use and learnability. Touchpad, voodoo doll and telescope techniques were found to be comparable for manipulating remote objects in a 3D scene. A flying camera technique was considered too complex and required increased effort by participants. Participants preferred an absolute mapping technique augmented to support small object manipulation, e.g. the voodoo doll technique.