Head-mounted displays

Augmented Reality (Display) Head-mounted display with transparent glasses that show semitransparent data or images superimposed over the wearer s field of vision to augment perception of or knowledge about reahty. 

Augmented reahty (AR) combines real worlds/objects with virtual worlds/objects. AR is a novel approach to the interaction between human and machine. It is possible, for example, to view information using a head-mounted display. The information is displayed context sensitive, which means that it depends on the observed objects, such as a part of an assembly. The engineer can now display job-related assembly data while viewing the real object. 

Visual displays are devices that present the virtual environments to the user. The degree of immersion given by a particular VE system depends greatly on the visual interface display. Severed kinds of visual displays are currently available monitors, head-mounted displays (HMDs), head-coupled displays (HCDs), and projection systems. AH of these systems are capable of producing wide-angle stereoscopic views of the scene, although in some cases monoscopic vision is tilso used. 

With a fully immersive VE, the user wears a head-mounted display (HMD) equipped with headphones and a visual stereo display directly in front of the eyes. The user is visually and acoustically sealed off from the physical environment and primarily perceives impressions the virtual environment. 

EUis, S. R., Breant, R, Menges, B., Jacoby, R., and Adelstein, B. D. (1997), Eactors InOuencing Operator Interaction with Virtual Objects Viewed via Head-Mounted See-Through Displays, in Proceedings of Virtual Reality International Symposium 97 (Albuquerque, March 1-5), IEEE Computer Society Press, Washington, DC, pp. 138-145. 

Head-mounted displays (HMDs), 2502 Health, occupational, see Occupational safety and health... 

Vision enhancement involves input from a camera, processing of the information, and output on a visual display. In its simplest form it may be a miniature head-mounted camera with the output on a head-mounted visual display (as used in some virtual reality systems). However, modern fast wearable computers make feasible sophisticated processing of the information in real time, and it is this factor which could transform interesting research projects into products of practical benefit to the bhnd and partially sighted people. 

Fig. 2.3 Vehicle in the Loop Vehicle, head-mounted display, and head-tracking [79]...

CBD common bile duct HMD head-mounted display... 

S. Fisher, Viewpoint dependent imaging An interactive stereoscopic display, Proc. SPIE, 0367,41(1983). 1.1. Khayrullin, I. Wacyk, T. A. Ali, et al., WUXGA resolution 3D stereoscopic head mounted full color AMOLED microdisplay, SID Tech. Digest, 43, 244 (2012). 

E. M. Howlett, High-resolution inserts in wide-angle head-mounted stereoscopic displays, Proc. SPIE, 1669, 193 (1992). 

E. Kambe, M. Nakamura, J. Yamada, et al.. Stable white OLED device stmcture for 3D-compatible head mounted display, SID Tech. Digest 43, 363 (2012). 

R. Zhang and H. Hua, Design of a polarized head-mounted projection display using ferroelectric liquid-crystal-on-silicon microdisplays, Appl. Opt. 47, 2888 (2008). 

Head-mounted display (HMD) An HMD is usually a helmet or a pair of glasses featuring a small optic display in front of each eye. Helmets are usually heavier but better cover the visual field, increasing the immersion. In contrast, glasses are lighter but provide less immersion. 

Head-mounted display High mohOity Wearing heavy helmet/glasses Lower image quality than that of a screen Too immersive (device covers most of the visual field)... 

A variety of novel image-presentafion mefhods have been proposed for example, heads-up displays, as in the works of Rolland and Fuchs [63] or Salb et al. [64], in which a semitransparent display is mounted directly onto the surgeon s head. The projection of images directly onto the patient anatomy has also been the subject of recent research examples include ceiling-mounted projection [65], in which the patient is positioned underneath the projector and the internal anatomy is displayed directly on the skin. Handheld projection has also been explored this allows hidden anatomy or targehng information to be displayed directly on the patient [66]. 

An output device is any tool that delivers information from a machine to a human. Again, the most familiar output devices are those associated with personal computers monitors, flat-panel displays, and audio speakers. Other output devices include wearable head-mounted displays or goggles that provide visual feedback directly in front of the user s field of vision and full-body suits that provide tactile feedback to the user in the form of pressure. 

This kind of virtual reahty technology wreis intended to improve flight simulators and apphcations for astronaut training. In 1981, the National Aeronautics and Space Administration (NASA) combined commercially available Sony hquid crystal display (LCD) portable television displays with special optics for a prototype stereo-vision head-mounted device called the Virtual Visual Environment Display (VTVED). NASA then created the first virtual reahty system, which combined a host computer, a graphics computer, a noncontact user position-tracking system, andVIVED. 

An early head-mounted device, developed in 1968 by Ivan Sutherland and Bob SprouU, displayed three-dimensional images by using two cathode-ray tubes. This helmet was so heavy that it had to be suspended from the ceiling. It was dubbed the Sword of Damocles, after the sword that hung on a horse hair over the head of Damocles, a courtier in ancient Greece. 

The first commercial head-mounted devices were called Eye Phones. They were introduced byjaron Lanier in 1989, sold for the price of 11,000 per set, and weighed 2.4 kilograms. The liquid crystal display (LCD) had a very low resolution-only 360 X 240 pixels. 

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