Effects of Viewpoint Oscillations and Gaze-based Stabilization on Walking Sensation, Embodiment and Cybersickness in Immersive VR.

When walking, our head does not travel on a straight path but oscillates in a swaying pattern. This pattern has been implemented in Virtual Reality (VR) as "viewpoint oscillations" - which can be defined as periodic changes in position and/or orientation of the point of view to enhance walking simulations and make them feel closer to real walking. Viewpoint oscillations are especially beneficial when users cannot physically walk because of limitations of space or hardware, disability, or to avoid fatigue. In this paper, we provide new experimental work on the effects of viewpoint oscillations on walking sensation, as well as cybersickness and virtual embodiment, since such results are scarce in immersive VR, especially when using an avatar in first-person view. To do so, we also propose a technical improvement of viewpoint oscillations in embodied VR. Our technique makes use of an HMD-embedded gaze tracker to artificially add rotations that stabilize the target of the gaze in the users' field of view. We conducted a user study on 24 participants, which showed that our implementation of viewpoint oscillations successfully increased walking sensation and did not impact cybersickness or agency, compared to a linear motion without oscillations. In addition, a novel positive effect of stabilized viewpoint oscillations was found on virtual body ownership. As such, this study demonstrates the feasibility and viability of implementing gaze tracking-based stabilization with standard commercial HMDs, and, taken together, our results promote the use of viewpoint oscillations during walking simulations in embodied VR with an HMD.