Virtual Walking With Omnidirectional Movies and Foot Vibrations: Scene-Congruent Vibrations Enhance Walking-Related Sensations and Ground Material Perceptions

Walking is a human need. Even when physical disabilities or social situations, such as the COVID-19 pandemic, prevent people from walking, virtual reality can provide an opportunity for virtual walking or travel. In this study, a virtual walking system was developed in which users view omnidirectional movies while receiving scene-congruent vibrations to their left and right forefeet and heels. The timings of foot vibrations were generated by estimating the camera motion trajectory with visual simultaneous localization and mapping (visual SLAM) applied to four omnidirectional movies. Congruent vibration patterns were prepared for four ground scenes. Modulation of walking-related sensations and ground material perceptions by congruent and incongruent vibrations was verified using psychological measurements. The results showed that rhythmic foot vibration improved the sensations of self-motion, walking, leg action, and telepresence irrespective of scene–vibration congruency. Moreover, congruent vibrations were better than incongruent vibrations for walking-related sensations and telepresence in indoor corridors and snowy ground scenes. The perception of ground materials was enhanced by scene-congruent vibrations, whereas it was confused by scene-incongruent vibrations. These findings suggest that vibration patterns do not necessarily need to match the ground exactly to induce virtual walking sensations; however, scene-congruent or similar vibrations improve virtual walking sensations and ground material perception. By applying our methods, we can convert various public omnidirectional movies into realistic virtual walking experiences.