The Object Inside: Assessing 3D Examination with a Spherical Handheld Perspective-Corrected Display

Handheld Perspective Corrected Displays (HPCDs) can create the feeling of holding a virtual 3D object. They offer a direct interaction that is isomorphic to the manipulation of physical objects. This illusion depends on the ability to provide a natural visuomotor coupling. High performances systems are thus required to evaluate the fundamental merits of HPCDs. We built a spherical HPCD using external projection. The system offers a lightweight wireless seamless display with head-coupled stereo, robust tracking, and low latency. We compared users' performances with this HPCD and two other interactions that used a fixed planar display and either a touchpad or the spherical display as an indirect input. The task involved the inspection of complex virtual 3D puzzles. Physical puzzles were also tested as references. Contrary to expectations, all virtual interactions were found to be more efficient than a more "natural" physical puzzle. The HPCD yielded lower performances than the touchpad. This study indicates that the object examination task did not benefit from the accurate and precise rotations offered by the HPCD, but benefited from the high C/D gain of the touchpad.