Augmented reality (AR) is a live direct or indirect view of a physical, real-world environment whose elements are “augmented” by computer-generated sensory input, such as sound, video, graphics or GPS data. It is related to a more general concept called mediated reality, in which a view of reality is modified (possibly even diminished rather than augmented) by a computer. As a result, the technology functions by enhancing one’s current perception of reality.
By contrast, virtual reality replaces the real world with a simulated one. Mixed reality is an extension of AR and VR that allows interaction between real and virtual objects.
The first use of the term “augmented reality” was in an Elisha Gray patent in 1890, for his “telespace scope”, although he did not publish any papers on the topic and it was never commercialized. The invention would have allowed its user to see through walls. In 1960 Morton Heilig invented and patented the Sensorama Simulator,”the first multi-sensory simulator providing recorded smell, sounds and vision stimuli synchronized with player body movements”.:24 This device would become known as “The Ultimate Display”.:158–159:290 Since Heilig’s original patents expired in 1977, numerous companies have built upon his work to create their own versions of what Heilig called “experience theaters”.:181 One example is Sega’s VirtuaCam from 1993,:108 which used animated 3D models superimposed on live video footage for game environments like Virtua Racing Deluxe. Another early example was VPL Research’s DataGlove system from 1985 which tracked finger position to provide three dimensional control of modeling clay sculptures displayed on an attached monitor.. These systems were very expensive though and thus appeal was limited to corporate or military uses where such high costs could be justified.
A key development leading to modern AR applications was head mounted displays (HMD). HMD devices combine miniaturized display screens placed directly in front of eyes with optics designed so that images appear correctly registered with respect to external scenes when users look around them normally while wearing them. First developed for military flight simulators during World War II,:38 they were quickly adapted for industrial uses including design engineering, maintenance training, machine tool setup, process control, quality inspection, assembly line supervision, surgery rehearsal,, dental prosthesis fitting ,,, endoscopic visualization ,and medical diagnosis support . However due largely to weight, cost and encapsulation issues they failed to achieve widespread consumer acceptance until recently.