Virtual reality
Around the same time, Douglas Engelbart used computer screens both as input and output devices. In 1968, Ivan Sutherland, with the help of many students including Bob Sproull, created what was widely considered to be the first head-mounted display (HMD) system for use in immersive simulation applications. It was primitive both in terms of user interface and realism, and the HMD to be worn by the user was so heavy that it had to be suspended from the ceiling. The graphics comprising the virtual environment were simple wire-frame model rooms. The formidable appearance of the device inspired its name, The Sword of Damocles.
The Sword of Damocles (virtual reality)
In 1963, Bell Helicopter company in Fort Worth, Texas experimented with a pilot controlled night vision system. The servo-controlled remote viewing device employed a headset displaying an augmented view of the ground for the pilot via an infrared camera mounted under the helicopter. The remote vision system display was similar to the Philco system. Ivan Sutherland's breakthrough was to imagine a computer to supply graphics output to the viewing device. Sutherland modestly stated, "My little contribution to virtual reality was to realize we didn't need a camera - we could substitute a computer. However, in those days no computer was powerful enough to do the job so we had to build special equipment"