Characterizing the Effect of Level of Immersion on a 3D Marking Task

We present a user study comparing multiple immersive environments for the performance of a task. We expected them to perform differently but it was not obvious how they would differ. Our analysis aimed to discover the environment in which subjects performed best and the environment they preferred. The task, derived from developmental biology, requires a user interactively to label spheres distributed in a volume by marking the spheres in 3D. We tested three virtual reality displays: a CAVE-like environment, a single-wall display, and a desktop system (fish tank virtual reality). All displays supported head-tracked stereo viewing and a tracked wand device. The task conditions varied in field of view, apparent size of the spheres, and whether the user was standing or sitting. We also varied the number of targets that had already been marked when the user began a trial. Popular user interaction techniques allow the user to change viewpoint and do the marking. Data we collected led to four significant findings: a) in the Cave the subjects preferred medium sized or large spheres over small spheres, b) when only a few of the targets have been marked, larger spheres were marked faster than small spheres, c) large spheres are marked most accurately, and d) our wall display is not comparable to our fish tank virtual reality environment when the spheres are small. Additionally, occlusion and larger field of view inhibited performance in the Cave more than at the fish tank when the task was dominated by visual search. (a) (b) (c) Figure 1: Marking spheres in different virtual environments: (a) at the fish tank, (b) at the single wall, and (c) in the Cave.