Telegeoinformatics: Location-Based Computing and Services

Chapter 9: Mobile Augmented Reality (PDF)

As computers increase in power and decrease in size, new mobile, wearable, and pervasive computing applications are rapidly becoming feasible, providing people access to online resources always and everywhere. This new flexibility makes possible new kind of applications that exploit the person's surrounding context. Augmented reality (AR) presents a particularly powerful user interface (UI) to context-aware computing environments. AR systems integrate virtual information into a person's physical environment so that he or she will perceive that information as existing in their surroundings. Mobile augmented reality systems (MARS) provide this service without constraining the individual’s whereabouts to a specially equipped area. Ideally, they work virtually anywhere, adding a palpable layer of information to any environment whenever desired. By doing so, they hold the potential to revolutionize the way in which information is presented to people. Computer-presented material is directly integrated with the real world surrounding the freely roaming person, who can interact with it to display related information, to pose and resolve queries, and to collaborate with other people. The world becomes the user interface.

One technology that is particularly interesting for mobile AR purposes is the one employed in Microvision’s monochromatic, single-eye, Nomad retinal scanning display, shown in Figure 9.6 (a). It is one of the few displays that can produce good results in direct sunlight outdoors. It works by pointing a red laser diode towards an electromagnetically controlled pivoting micromirror and diverting the beam via an optical combiner through the viewer’s pupil into the eye, where it sweeps across the retina to recreate the digital image. This technology produces a very crisp and bright image, and exhibits the highest transparency any optical seethrough display offers today. Microvision has also prototyped a much larger, fullcolor and optionally stereoscopic display.

In our experience, monocular displays can yield acceptable results for AR if the display is see-through to make it easier for the user to fuse the augmented view with the other eye’s view of the real world, as is the case with the Microvision Nomad.

Displays are for the most part still bulky and awkward in appearance today. Smaller monocular displays, such as the MicroOptical CO-1, pictured in Figure 9.6 (b), or the Minolta ‘Forgettable Display’ prototype (Kasai et al., 2000), are much more inconspicuous, but do not afford the high field-of-view angles necessary for true immersion nor the brightness of, for example, the Microvision Nomad.

Meanwhile, manufacturers are working hard on improving and further miniaturizing display optics. Microdisplays can today be found in a diverse set of products including viewfinders for cameras, displays for cell phones and other mobile devices, and portable video projectors. Near-eye displays constitute a growing application segment in the microdisplay market. The attractiveness of mobile AR relies on further progress in this area.