Rotational and Translational Velocity and Acceleration Thresholds for the Onset of Cybersickness in Virtual Reality
Lorenzo Terenzi, Peter Zaal
Abstract
Cybersickness causes strong, discomfort and discourages the widespread use of VR system for both recreational and professional use. Visual motion or optic flow is known to be one of the main causes of cybersickness due to the sensory conflict it creates with the vestibular system. Participants were exposed, for few seconds per run, to to a particle field in VR. The field had different motion types, translation forward and lateral and rotation along the roll and yaw axis, different velocity profiles, steady and accelerating, and different densities. Using a staircase procedure, that controlled the speed or acceleration of the field, we detected the threshold at which participant started to feel temporary symptoms of cybersickness. The optic flow in each scene was modeled and by modifying the density of the fields it was ensured that all the scene had the same amount of optic flow to allow a direct comparison of the thresholds. The results showed that optic flow thresholds detected for rotational cases is significantly lower than the one for translation cases. Furthermore, accelerations significantly reduced the detected threshold but only for the translations cases. The thresholds suggestively decreased with the decreasing particle density of the scene. Finally, it was found that all the rotational and translational cases strongly correlate with each other. While the mean values of the thresholds could be used as guidelines to develop VR applications, the high individual variability implies that individual tuning of the motion controls would be more effective at reducing cybersickness while minimizing the impact on the experience of immersion.