A psychophysically calibrated controller for navigating through large environments in a limited free-walking space

Abstract

Experience indicates that the sense of presence in a virtual environment is enhanced when the participants are able to actively move through it. When exploring a virtual world by walking, the size of the model is usually limited by the size of the available tracking space. A promising way to overcome these limitations are motion compression techniques, which decouple the position in the real and virtual world by introducing imperceptible visual-proprioceptive conflicts. Such techniques usually precalculate the redirection factors, greatly reducing their robustness. We propose a novel way to determine the instantaneous rotational gains using a controller based on an optimization problem. We present a psychophysical study that measures the sensitivity of visual-proprioceptive conflicts during walking and use this to calibrate a real-time controller. We show the validity of our approach by allowing users to walk through virtual environments vastly larger than the tracking space

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

“…Further, they compared different generalized approaches for redirected walking and proposed improvements to the S2C algorithm [8]. Engel et al [3] proposed a psychophysically calibrated controller that employs a cost function based on the noticeability of redirection. Nitzsche et al [12] and Su et al [19] suggested an approach that dynamically minimizes the introduced curvature, but does not make imperceptibility a primary goal.…”

“…The resulting J 0 (x 0 ) is the optimal cost and the minimization in (3) gives the set of optimal control laws µ k (x k ) for each stage k, see [1]. The control laws provide the optimal action u k for each state at the corresponding stage.…”

“…Engel et al [3] showed how such a cost function based on the noticeability might look like. In the study presented below, a cost function for rotational RETs and simple resets is proposed and evaluated.…”

Walking in a Cube: Novel Metaphors for Safely Navigating Large Virtual Environments in Restricted Real Workspaces

“…Redirected Walking [16,21,10] and Motion Compression [13,7,22] techniques "trick" the user into walking in a curved path in the real world when walking in a straight line in the virtual world through the progressive rotation of the scene around them. In a sufficiently large workspace, and with a straight virtual path, the user can walk endlessly without reaching the limits of the real workspace.…”

Sharing and Stretching Space with Full Body Tracking

“…A group of techniques have been initiated to address this issue. Redirected walking is one technique used to subtly rotate the virtual environment, preventing users from encountering walls [11,6]. Distracting objects can help make these redirections less noticeable [10].…”