| Four novel interfaces were created in an investigation of force constrained interaction techniques as an interface for object manipulation in virtual environments. For object rotation, two interfaces were produced, widgets and virtual sphere. The widget interface consists of three touchable handles, each implying an angular constraint on the virtual object as well as a force constraint on the user. The virtual sphere interface looks, acts, and feels like a physical trackball. For object translation, force enhanced snap-to-grid and friction interfaces were implemented. Attractive forces towards known grid points create a feel of snap to grid. Movement resistive forces exerted on the controller simulate friction. These interaction techniques were tested against standard 3-D interfaces.; To evaluate the effectiveness of these interfaces a set of translation matching, rotation matching and arbitrary axis rotation experiments were conducted. The translation-matching experiment showed better accuracy for the snap-to-grid interface over the non-constrained control case, with no significant differences in speed. Two orientation matching experiments both revealed no significant differences between the rotation interfaces. However, rotations about arbitrary axis showed the potential of the constraint based rotation interfaces, resulting in significant improvements in both the widgets and virtual sphere interfaces in both speed and accuracy.; The experiments in this research led to the development of a guiding principle for haptic constraint interfaces: “Constraints should appear visually as well as haptically when they become active to avoid ambiguities”. |
