Nailing down multi-touch: Anchored above the surface interaction for 3D modeling and navigation

visualization. Center: A user bends a mesh while simultaneously specifying the curvature of the bend. Right: A user twists a 3D mesh by placing his hands on top of each other and rotating. (A digital rendering is superimposed to illustrate the stereoscopic effect of the display.) We present anchored multi-touch, a technique for extending multi-touch interfaces by using gestures based on both multi-touch sur-face input and 3D movement of the hand(s) above the surface. These interactions have nearly the same potential for rich, expres-sive input as do freehand 3D interactions while also having an ad-vantage that the passive haptic feedback provided by the surface makes them easier to control. In addition, anchored multi-touch is particularly well suited for working with 3D content on stereo-scopic displays. This paper contributes two example applications: (1) an interface for navigating 3D datasets, and (2) a surface bend-ing interface for freeform 3D modeling. Two methods for sensing the gestures are introduced, one employing a depth camera