a comparison of immersive hmd, fish tank vr and fish tank with haptics displays for volume visualization
Although a wide range of virtual reality (VR) systems are in use, there are few guidelines to help system and application developers select the components most appropriate for the domain problem they are investigating. Using the results of an empirical study, we developed such guidelines for the choice of display environment for four specific, but common, volume visualization problems: identification and judgment of the size, shape, density, and connectivity of objects present in a volume. These tasks are derived from questions being asked by collaborators studying Cystic Fibrosis (CF). We compared user performance in three different stereo VR systems: (1) head-mounted display (HMD); (2) fish tank VR (fish tank); and (3) fish tank VR augmented with a haptic device (haptic). HMD participants were placed "inside" the volume and walked within it to explore its structure. Fish tank and haptic participants saw the entire volume on-screen and rotated it to view it from different perspectives. Response time and accuracy were used to measure performance. Results showed that the fish tank and haptic groups were significantly more accurate at judging the shape, density, and connectivity of objects and completed the tasks significantly faster than the HMD group. Although the fish tank group was itself significantly faster than the haptic group, there were no statistical differences in accuracy between the two. Participants classified the HMD system as an "inside-out" display (looking outwards from inside the volume), and the fish tank and haptic systems as "outside-in" displays (looking inwards from outside the volume). Including haptics added an inside-out capability to the fish tank system through the use of touch. We recommend an outside-in system because it offers both overview and context, two visual properties that are important for the volume visualization tasks we studied. In addition, based on the haptic group's opinion (80\% positive) that haptic feedback aided comprehension, we recommend supplementing the outside-in visual display with inside-out haptics when possible.
fish tank haptics visualization virtual reality volume rendering head mounted display force feedback