Two-handed direct manipulation on the responsive workbench

We have built a system that allows users to naturally manipulatevir-tual 3D models with both hands on the Responsive Workbench, a tabletop VR device. Our design is largely based upon Guiard’s observations of how humans distribute work between the two hands in the real world. We show how to apply these principles for the workbenchenvironmentand describe many issues encountered during the design. We first develop a framework for two-handed interaction and then explore a variety of two-handed 3D tools and interactive techniques. Related issues include how constraints are implemented and controlled by the two hands and how transitions be-tween one-handedandtwo-handedtasksoccurseemlessly. Informal observations of the system in practice show that users can perform navigation and manipulation tasks easily and with little training us-ing the two-handed environment. One of our interesting findings was that users often performed two-handed manipulations by combining two otherwise independent one-handed tools in a synergistic fashion. In these cases, we did not program two-handed behaviors explicitly into the system; instead they emerged naturally.