We use a Kinect to detect real-world objects in a space and transform them into VR obstacles. This will allow you to wander freely in the real world while being fully immersed in your virtual reality.
https://docs.google.com/a/andrew.cmu.edu/document/d/1-bcZTBbmHSOlzSbEhNklTtq7_Pa03g9SE009fzZV42A/edit?usp=sharing