Mentioned in this article are interesting room tracking possibilities:

A gyrosensor, accelerometer, and laser position sensor combine to precisely track the rotation of your head on both axes to an accuracy of 1/10th of a degree, allowing you to look around the virtual environment naturally. Couple the headset with a pair of Steam VR base stations to track your physical location (in spaces up to 15 feet by 15 feet) – get up and walk around inisde the virtual world!

–Also they don’t want you to walk into the walls so this Fortune article talks about the ‘Pass thru’ camera:

New on the Vive Pre is the new front-facing camera, which is being used in two ways. As part of the “chaperone system,” the camera overlays real-world items like walls, chairs, and tables into the virtual world for a mixed reality experience to ensure users don’t walk into things as they’re playing games or exploring experiences.

This “pass-through camera” safety feature is customizable, as users can assign the dimensions of their play space when setting up the system. Unlike Facebook’s Oculus Rift, the HTC Vive has been designed to allow navigation through a real-world room while exploring virtual worlds. The new camera replaces the grid system that previously would interrupt a virtual reality experience to alert a user that a wall or other object was nearby.

O’Brien says users also can turn on the pass-through camera at any time during a session by pressing a button combination on the controller. This makes it easy for consumers to see and communicate with friends in the room, or find a chair for a sit-down virtual reality experience.