At the Homebrew Robotics Club we had a number of sessions on 'localization', which was as you might expect figuring out where you were in a room. Carpet was a real pain. One of my robots (wheeled) had excellent sensors and no wheel slip but I discovered that the 'weave' of the carpet would bias the whole robot to travel slightly sideways to the direction of travel, it was so annoying. I put 'pingers' in my lab, basically synchronized sources of sound and tried to do triangulation based on arrival time with limited success, the camera should be able to do much better than that. Especially if there are already 2 or three distinctive features (lights, doorways etc).