Biomedical Engineering Reference
In-Depth Information
Section
7.2
will cover display systems for VEs.
Section
7.3
will cover tracking and interaction devices.
Section
7.4
will describe the range of travel metaphors that are commonly used.
7.2 Display Systems
Display systems for VEs come in many sizes, form factors and capabilities. We
distinguish a few types of display:
•
Desktop displays
•
Wall-sized displays
•
Surround-screen displays
•
Head-mounted displays
•
Mobile augmented reality displays
•
Hybrid situated displays
By a desktop display we mean a display such as a humble monitor or TV of the
type that is found in most offices or homes. It may show a VE, or other media, but it
does not cover a large proportion of the user's vision compared to other displays. The
display might use stereo and/or head tracking, but the display doesn't surround the
user, so it can only provide a small window into the VE. Obviously one can represent
self-motion on such a display. Indeed, many modern video games focus on travel
and exploration around a VE, but many of the perceptual cues received are unlike
the ones received from actual self-motion. For example, the cues do not extend into
peripheral vision.
Once a display becomes very large, such as a single wall of a room (Fig.
7.1
),
then it covers much more of the user's vision. One characteristic of such a display
is that nearby items such as other humans can be depicted “life-size” (with realistic
scale) and thus the representation of self-motion can exploit the fact that the user
will be able to judge heights more accurately, since he can have an eye-level that can
corresponds to his actual height. The displays might be flat (e.g., an actual room wall)
or they might be large curved screens. A key characteristic is that the display system
is not fully surrounding, so it is possible for the user to turn away from it. Thus any
walking interface using such a display would normally require some facility to turn
the viewpoint.
At this scale, it is much more common to provide stereoscopic viewing of the
display. There are several technologies for this such as shutter glasses, polarising
glasses, or color filters. Each works by presenting separate images to the left and
right eyes. Most displays of this type support only a single user with head-tracked
stereo, but multiple users can be supported [
1
]. The current state of the art is the
C1X6 (Fig.
7.2
), a prototype display that supports six users, each with a stereo view
from her own viewpoint [
15
].
The next type of display is a surround-screen display (SSD), of which the most
common type comprises multiple large flat display surfaces. These displays are often