At University of Groningen in the Netherlands students were able to take a 3-D theater and turn it into a 33-foot long touch screen. The screen is used for teaching computer science and math. They used six HD video projectors to backlight the screen. Then for the touch screen they used six Optitrack cameras, 16 inexpensive infrared emitters, and 1,000 LEDs. They connected the cameras to three older computers. Then the computers are used to make the screen a touch screen. The system is able to handle one hundred points of connect in real time. With more touch, the system slows down.