Estimation of Detection Thresholds for Redirected Walking Techniques

Abstract

In immersive virtual environments (IVEs), users can control their virtual viewpoint by moving their tracked head and walking through the real world. Usually, movements in the real world are mapped one-to-one to virtual camera motions. With redirection techniques, the virtual camera is manipulated by applying gains to user motion so that the virtual world moves differently than the real world. Thus, users can walk through large-scale IVEs while physically remaining in a reasonably small workspace. In psychophysical experiments with a two-alternative forced-choice task, we have quantified how much humans can unknowingly be redirected on physical paths that are different from the visually perceived paths. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotations, (E2) discrimination between virtual and physical straightforward movements, and (E3) discrimination of path curvature. In experiment E1, subjects performed rotations with different gains, and then had to choose whether the visually perceived rotation was smaller or greater than the physical rotation. In experiment E2, subjects chose whether the physical walk was shorter or longer than the visually perceived scaled travel distance. In experiment E3, subjects estimate the path curvature when walking a curved path in the real world while the visual display shows a straight path in the virtual world. Our results show that users can be turned physically about 49 percent more or 20 percent less than the perceived virtual rotation, distances can be downscaled by 14 percent and upscaled by 26 percent, and users can be redirected on a circular arc with a radius greater than 22 m while they believe that they are walking straight.

Does direction of walking impact binocular rivalry between competing patterns of optic flow?

“…Our participants were walking in a circle, and the radius of the circle was within their biomechanical threshold of detection (Steinicke et al, 2010). The optic flow patterns they viewed, however, comprised linear motions, meaning the visual stimuli did not perfectly match the biomechanical concomitants of walking.…”

Planning redirection techniques for optimal free walking experience using model predictive control

“…When the reset was done, the arrow changed to a tick mark and then disappeared to notify the participants that they may continue walking. With this reset technique, the applied rotation gains comply with the detection thresholds determined in [18].…”

“…Furthermore, they evaluated detection thresholds for different RETs [17,18]. Neth et al studied the velocity dependency of so-called curvature gains, i.e.…”

“…ρ c is the curvature gain as defined in [18]. The sign of ρ c determines the direction of the redirection.…”

“…ρ q is the rotation gain which is different for rotations with or against the head movement. Due to the additive formulation of the rotational redirection function, ρ q is given as (1 − gain R ) for gain R as defined in [18]. A specific rotational RET action is now defined by a specific ρ c and ρ q .…”