Date of Award

Spring 5-3-2024

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Computer Science

Advisor

Terry S. Yoo

Second Committee Member

Benjamin Guenther

Third Committee Member

Penny Rheingans

Abstract

This research directly compares natively head tracked spatial displays against actively head tracked ones. The belief is that by suppressing the latency, emulation of object presence can be improved. Modern Virtual Reality (VR) headset systems target 90Hz refresh rates in order to reduce tracking latency, yet with such low latencies, users still report motion sickness. Frame rates in film target 24-30Hz for smooth motion. This disconnect between frame rates for smooth motion and head tracking speed indicates that they may not be related. This thesis addresses these questions of latency and animation speed by building two display systems, a native head tracked and an actively head tracked one, and directly compares them in human testing. One of these display systems which is known as a ”praxigraph” is based on the design of a praxinoscope and does not require active head tracking to provide the correct positional perspective on an object. These properties lead to the praxigraph also being autostereo, as each eye is given a different perspective. A second display design based on fish tank VR systems uses active head tracking to achieve the same goal as the first system, but does so in a way designed to reduce simulation sickness by not removing users’ peripheral vision. This head tracked system also increases ergonomics over headset based systems by requiring less hardware to be worn by the user. In addition, a control display which consisted of a computer monitor that allowed the user no interaction was used to establish baseline results. The display systems were compared and analyzed by asking 16 participants perform accuracy tasks that were designed based on previous works. Participants were also asked to provide their opinions on animation quality by scoring a walking animation displayed at different frame rates as better or worse than a desired rating on a scale. Due to design difficulties, the praxigraphic display was found to be difficult to use due to rapidly wobbling images in the prototype. The head tracked display was comparatively accurate and no users reported simulation sickness-related discomfort when using it. Results concerning disconnecting the animation frame rate from the tracking frame rate are encouraging, with users on the head tracked and control displays selecting similar frame rates when asked to target specific scores on a rating scale. Once again, issues with the praxigraphic display prevented meaningful comparison in this test. Despite the inability to prove that natively head tracked spatial displays provide a better experience, both display systems warrant future testing with improvements to ergonomics and clarity. The praxigraphic display research suggested differences between left-handed and right-handed users which should be investigated further, but due to experimental design these differences cannot be claimed to be statistically significant.

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