Shared virtual reality

An immersive three dimensional (3-D) virtual reality sharing system is disclosed. The system comprises a content controller configured to determine the physical locations of a reference point and boundary in a physical space and map them to a corresponding point and boundary in a virtual world. The physical location and orientation of a user device relative to the reference point and boundary are used to determine a corresponding location and orientation in the 3-D virtual world. A representation of a portion of the 3-D virtual world corresponding to the determined location and orientation is rendered at the user device. As the user device is moved in the physical world, a corresponding updated location in the 3-D virtual world is determined, and the rendered representation updated. Thus, the user device acts as a window into the 3-D virtual world.