Shaking Hands in Virtual Space: Recovery in Redirected Walking for Direct Interaction between Two Users

Various studies have been conducted to realize realistic direct interaction in the virtual environment. In this study, we focus on a situation wherein two users using the same physical space explore the same virtual environment using redirected walking (RDW) technology. For two users to meet each other in a virtual environment to realize realistic direct interaction, they must simultaneously meet each other in physical space. However, if the RDW algorithm is applied to each user independently, the relative positions and orientations of the two users can be significantly different in the virtual and physical spaces. We present a recovery algorithm that adjusts the relative position and orientation such that they become the same in the two spaces. Our recovery algorithm uses either modified subtle RDW techniques or overt recovery techniques in three cases depending on the relative position and orientation of the two users. Once the recovered state is reached, the two users can go forward to meet each other and directly interact in the virtual and physical spaces simultaneously. Based on the experiment results, we can confirm that the application of our recovery technology to the system increases the user's satisfaction in usability and the presence of coexistence in the virtual environment with other users.