ESTIMATION OF DETECTION THRESHOLDS FOR REDIRECTED WALKING TECHNIQUES 2 Estimation of Detection Thresholds for Redirected Walking Techniques

In immersive virtual environments (IVEs) users can control their virtual viewpoint by moving their tracked head and by 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 tasks we have quantified how much humans can unknowingly be redirected on virtual paths which are different from the physical paths that they actually walk. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotation, (E2) discrimination between virtual and physical translation, 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% more or 20% less than the perceived virtual rotation, distances can be downscaled by 14% and up-scaled by 26%, and users can be redirected on a circular arc with a radius greater than 22m while they believe they are walking straight.