First-generation Interactive Headsets - Text 3
In 1968 Ivan E. Sutherland, after two years of work, finished work on a “head-mounted three-dimensional display,” seen today as the “first virtual reality headset” (in the official version of this story).
In the article which introduced this system (no patent application was filed), Sutherland described the goal of his research:
The fundamental idea behind the three-dimensional display is to present the user with a perspective image which changes as he moves... The image presented by the three-dimensional display must change in exactly the way that the image of a real object would change for similar motions of the user’s head.[3]
This system was similar to that of Bradley (although Sutherland mentions it nowhere). It included two cathode-ray tubes and a binocular interface, but nevertheless was not stereoscopic: “Although stereo presentation is important to the three-dimensional illusion, it is less important than the change that takes place in the image when the observer moves his head.”[4] The image appears to be three-dimensional without being so, simply because it is interactive; it is spatial because it is kinaesthetic. Sutherland, moreover, speaks of a “kinetic depth effect.”[5]
Movements of the head and transformations of the image were coupled by means of two systems for following movement, similar to those of Bradley. The first was mechanical: a metallic arm was attached to the ceiling with a sliding central section which made possible vertical transference movements at high altitude, with two universal joints which enabled all the other rotational and transference movements. The second system was ultrasonic: three transmitters were mounted on the headset of the user and four receivers were mounted on a cross-like structure attached to the ceiling, making it possible to measure the changes of phase, meaning the changes of position, between the head and the reference system.
