Anisotropic human performance in six degree-of-freedom tracking: An evaluation of three-dimensional display and control interfaces

Motivated by the need for human performance evaluations of advanced interface technologies, this paper presents an empirical evaluation of a three-dimensional (3-D) interface, from the point of view of both display and control, in a pursuit tracking experiment. The paper derives methods for decomposing tracking performance into six dimensions (three in translation and three in rotation). This dimensional decomposition approach has the advantage of revealing overall performance levels in the depth dimension relative to performance in the horizontal and vertical dimensions. With interposition, linear perspective, stereoscopic disparity and partial occlusion cues incorporated into a single 3-D display system, subjects' tracking errors in the depth dimension were about 45% (with no practice) to 35% (with practice) larger than those in the horizontal and vertical dimensions. It was also found that subjects initially had larger tracking errors along the vertical axis than along the horizontal axis, likely due to their attention allocation strategy. Analysis of rotation errors generated a similar anisotropic pattern. By applying the dimensional decomposition method, the paper also analyzes the issue of coordinated control of six degrees of freedom with one hand. It was found that when the subject could not control all six degrees of freedom well, translational aspects of the task were given higher priority than the rotational aspects. After 40 min of practice, more than 80% of subjects were able to control both translational and rotation aspects together. © 1997 IEEE.