Reducing VR Sickness by Directing User Gaze to Motion Singularity Point/Region as Effective Rest Frame

Simulation sickness is one major obstacle in proliferation of virtual reality. The sensory mismatch between the visual and vestibular senses about user motion is attributed as the main cause. One effective method has been the use of the rest frame, which refers to the reference object that remains fixed in position with respect to the user. A popular choice of the rest frame is the virtual nose, but it can direct one's attention away from the main part of the navigation content. We propose to instead use the area within the screen space that represents the least amount of motion in the navigation content, called the Motion Singularity Point/Region (MSP/R) as such a rest frame. Viewing such a region is thus expected to reduce the sensory conflict and ensuing sickness. Such a region can be found by analyzing the content with respect to motion and estimating the region(s) of the image space with the least relative amount of the total optical flow. We experimentally validated the VR sickness reduction effect of looking at the MSP/R compared to that of the virtual nose. In addition, we confirmed that the content agnostic MSP/R to be much coinciding with the user's natural viewing direction, making it less distracting from the main content. This makes the MSP/R a more practical and viable rest frame object for sickness reduction than the virtual nose.