Supporting Free Walking in a Large Virtual Environment: Imperceptible Redirected Walking with an Immersive Distractor

Redirected walking, a technique in which the user's orientation in the physical space is constantly and imperceptibly changed from their orientation in the virtual world, has been shown to be an effective technique when only a limited physical space is available. Unfortunately, previous efforts have restricted redirected walking applications to operate under the constant supervision of researchers to prevent the users from leaving the tracked area. In addition, Virtual Environments (VE) used in these applications were often limited to narrow hallways, mazes or predefined waypoints, while the performance of redirected walking in a large, open VE is not well explored. In this paper, we introduce the idea and implementation for an imperceptible redirected walking system that supports the illusion of free walking in a large, open virtual environment with minimal amount of physical interventions, by integrating the distractor into the user's main immersive activity in the VE. We demonstrate this new approach with two user studies of an immersive interactive game. Our study indicates that for the majority of the subjects, the illusion is maintained of unconstrained walking in a very large area (a full-size basketball court, 50 feet x 95 feet), even while they were limited to a physical area of a mere 6% of the size of the basketball court (16 feet x 16 feet tracked area). Our result demonstrates that the illusion of free walking is created, since a majority of them was not interrupted by the researchers and did not realize they were redirected, and the 34 subjects took vastly different routes to reach the distant goal (See Figure 2). We believe that this technique demonstrates a more immersive way of designing redirected walking application and shows possibility of bringing redirected walking applications out of the monitored lab environments. Our result may provide insights for the designers of immersive experiences to create other redirected walking applications for consumer VR systems with room-size tracking.