Research On Redirection Walking Algorithm In Virtual Roaming System

Virtual reality provides users with multi-sensory information simulation and stimulation such as vision,hearing and touch,and uses computers to generate a simulated environment in which users can immerse themselves.In the virtual scene,if users can roam in a real way,they can greatly improve the sense of experience and immersion.However,the real space is often limited by the size and shape of the space,which conflicts with the openness of the virtual scene.How to roam large-scale virtual scenes in as small real space as possible is research difficulty and hotspot in this field.While roaming freely in the virtual scene,ensuring that users can reduce the number of times of colliding the wall in the real space,reduce the roaming time and improve the smooth sense of experience has become the main challenge and problem in this field.This study proposes the redirect walking algorithm based on buffer strategy.The algorithm maps the virtual straight-line path into three arcs with different curvature in the tracked space,and proposes the buffer mechanism through the pre-judgment strategy,so that users can reduce the potential number of wall collisions through guiding and turning in the buffer.Firstly,the user determines the starting point and end point of roaming,and uses Voronoi diagram to generate roaming path;Then the virtual path is divided into multi-segment straight paths and mapped segment by segment.In the mapping process,the arc of the safety area,the arc of the buffer and the walking arc between them are designed according to the next path length of the user.Compared with the classical algorithm S2 C,the experiment shows that this algorithm rarely needs reset operation,and the user roaming time is reduced by 70%,which improves the fluency of user roaming;The average distribution of user footprints shows that the algorithm can make full use of the tracking area and effectively avoid collision while multiple people roam.Although the number of colliding the wall is reduced,this method will inevitably produce a large instantaneous rotation rate while guiding the user away from the space boundary in the buffer,which will have great impact on the user’s immersion experience.In order to further improve the user’s immersion experience,this study proposes the mapping based redirected walking algorithm.The analysis shows that one-time steering will produce large instantaneous rotation rate.To solve this problem,this study proposes the divide and conquer strategy,which maps the virtual straight-line path into a curve in the multi-segment tracking space,and guides the user away from the boundary of the tracking space with a low rotation rate.Firstly,the virtual path is divided into a group of straight paths;Then,using the constraints between adjacent curves,each path is mapped and connected one by one by minimizing the internal energy of Bézier curve;Finally,the continuous and smooth curves in the tracking space are obtained.Through comparative experiments,the algorithm does not need to be reset,so the user roaming time is reduced by half,and the roaming speed is effectively accelerated;The instantaneous rotation rate of the algorithm is mostly distributed around 0-15 deg/s.The algorithm can guide users to roam the virtual scene at a lower rotation rate,so as to reduce perceptual distortion;User footprints are evenly distributed in the tracking area,which shows that the algorithm has advantages in dealing with multiple users roaming the virtual scene at the same time.Finally,this thesis implements a general redirection walking system.The system does not limit the hardware configuration of the target platform,and different head mounted display devices and tracking systems can be used.This thesis adopts a low-cost hardware configuration more suitable for ordinary users: Kinect tracking system and Card Board head mounted display device.The system uses natural interaction to guide users to roam the virtual scene,reset and deal with exceptions;In addition,the flexible architecture of the system is easy to expand,which provides a platform for researchers to deploy and test other redirection algorithms.In this study,a large number of user research experiments are carried out combined with the system.Users score the subjective measurement indicators,and the scoring results show the usability and robustness of the system.