Frames of Reference in Virtual Object Rotation

It is difficult with most current computer interfaces to rotate a virtual object so that it matches the orientation of another virtual object. Times to perform this simple task can exceed 20 seconds whereas the same kind of rotation can be accomplished with real objects and with some VR interfaces in less than two seconds. In many advanced 3D user interfaces, the hand manipulating a virtual object is not in the same place as the object being manipulated. The available evidence suggests that this is not usually a significant problem for manipulations requiring translations of virtual objects, but it is when rotations are required. We hypothesize that the problems may be caused by frame of reference effects---mismatches between the visual frame of reference and the haptic frame of reference. Here we report two experiments designed to study interactions between visual and haptic reference frames space.In our first study we investigated the effect of rotating the frame of the controller with respect to the frame of the object being rotated. We measured a broad U--shaped relationship. Subjects could tolerate quite large mismatches, but when the orientation mismatch approached 90 degrees performance deteriorated rapidly by up to a factor of 5. In our second experiment we manipulated both rotational and translational correspondence between visual and haptic frames of reference. We predicted that the haptic reference frame might rotate in egocentric coordinates when the input device was in a different location than the virtual object. The experimental results showed a change in the direction predicted; they are consistent with a rotation of the haptic frame of reference, although only by about half the magnitude predicted. Implications for the design of control devices are discussed