Effects of Field-of-View Expansion Using a Wide-field HMD on Active Linear Motion
Authors: Koishi Tomoya , Watanuki Keiichi , Kaede Kazunori 
Published: June 2022

Field-of-view (FOV) expansion is a technology that exceeds the limits of the human FOV, which is approximately covers 200° horizontally and 130° vertically, by compressing and presenting out-of-field images obtained from a wide-angle camera on a head-mounted display (HMD). Previous studies have focused on improving the search efficiency of the human FOV and detecting hazards not covered by blind spots by expanding the visible range; their effectiveness has only been examined in static situations. Therefore, the effect of FOV expansion in dynamic situations, such as during walking and exercise, has not been fully investigated and elucidated. Therefore, we attempted to investigate the characteristics of FOV expansion in dynamic situations that utilized peripheral vision by using a wide-field HMD. Among these, we focused on human motion perception during straight-line motion, which is closely related to human vision.In daily life, we perform linear movements such as walking and driving. In such movements, the human body acquires various types of information from its receptors to understand its own motion and position in relation to the outside world. This cognitive function is called self-motion perception, and visual motion information is the largest component of it. Therefore, there are many cases wherein visual information is manipulated to create an illusion of relative distance and speed to the external world, thereby enhancing motor sensation and altering walking patterns.Returning to the principle of FOV expansion, it is a method of presenting visual information beyond the limits of a defined human FOV. Therefore, the visual distance to external objects and the motion of the external objects change significantly in the FOV during FOV expansion. Utilizing this property, we believe that motion perception can be intentionally manipulated during straight-line walking. In addition, since the effects on perception propagate to the psychological states and physical control of the individual, walking in the state of an expanded visual field may induce mental elevation and improve their motor skills. If these characteristics can be clarified, the technology of visual field expansion can be applied not only to searching for entities and detecting danger but also to improving motion support and gait control.Based on the above, this study aims to investigate whether there are any differences, among normal walking, walking with FOV expansion, and walking with FOV expansion under different angles, in terms of perception, emotion, and gait. Perception and emotion were subjectively evaluated using a questionnaire, and the gait pattern was analyzed using body coordinate information obtained by motion capture. To expand the visual field, we constructed an FOV expansion system using a wide-field head-mounted display (HMD), two omnidirectional cameras, and a control PC. The results of the experiment indicated that the greater the expansion of the FOV, the faster the subject perceived their own walking speed. In addition, there was one case wherein the faster the perceived walking speed was, the shorter the perceived walking distance was. These results suggested that FOV expansion could create the illusion of increased athletic performance.