blob detection

today in class we were shown "blob detection" - so i could put a camera on the ceiling of a room and know where everyone was standing - then i could take that data and feed it to a 3D environment. When the cost of headmounted video displays drop from current level of hundreds of dollars, it could be very cheap to create a virtual world. . . so if i am wearing the goggles and so are you and we get within the "line of sight" in a virtual maze of objects then we'd see eachother. pretty cool stuff