Augmented-Reality Displays

Recent technological advancements in virtual environment equipment have led to the development of augmented reality displays for applications in medicine, manufacturing, and scientific visualization (Bajura et al., 1992; Janin et al., 1993; Milgram et al., 1991; Lion et al., 1993). However, even with technological advances in virtual environment equipment, the development of augmented reality displays are still in the early stages of development, primarily demonstrating the possibilities, the use, and the technical realization of the concept. The purpose of this chapter is to review the literature on the design and use of augmented reality displays, to suggest applications for this technology, and to suggest new techniques to create these displays. In addition, the chapter also discusses the technological issues associated with creating augmented realities such as image registration, update rate, and the range and sensitivity of position sensors. Furthermore, the chapter discusses humanfactors issues and visual requirements that should be considered when creating augmented-reality displays. Essentially, an augmented-reality display allows a designer to combine part or all of a real-world visual scene, with synthetic imagery. Typically, the real-world visual scene in an augmented-reality display is captured by video or directly viewed. In terms of descriptions of augmented reality found in the literature, Janin et al. (1993) used the term “augmented reality” to signify a see-through head-mounted display (HMD) which allowed the user to view his surroundings with the addition of computer graphics overlaid on the real-world scene. Similarly, Robinett (1992) suggested the term “augmented reality” for a real image that was being enhanced with synthetic parts; he called the result a “merged representation”. Finally, Fuchs and Neuman (1993) observed that an augmented-reality display combined a simulated environment with direct perception of the world with the capability to interactively manipulate the real or virtual object(s). Based on the above descriptions, most current augmented-reality displays are designed using see-through HMDs which allow the observer to view the real world directly with the naked eye. However, if video is used to capture the real world, one may use either an opaque HMD or a screen-based system to view the scene (Lion et al., 1993).