Biomedical Engineering Reference
In-Depth Information
applying the findings of research conducted in model- or small-scale environments
[
10
-
12
] to applications that require users to navigate large-scale VEs.
To overcome the above issues with the scale of a VE, it is common for studies of
full walking interfaces to condense an environment so that it fits within the physical
space of a laboratory. This leads to a situation where the environment is large-scale,
but its
spatial extent
(physical size) is small (say, less than 10
10m) [
13
-
15
].
This is rather unrealistic (in both VE applications and the real world a large-scale
environment is almost always also large in extent), but necessary for the purposes of
the experiment. However, extent changes the time cost of traveling from one place to
another and influences navigational behavior [
16
]. Fewwalking studies have actually
investigated the effect of extent, but a notable exception is [
17
].
In early VE navigation studies it was rare for a visually rich environment to be
used (a notable exception was [
18
]), but this richness is now more common, partly
due to the ability of PC graphics cards to render complex scenes in real time. Real-
world environments and modern VE applications typically contain a surfeit of visual
cues, which compete to become landmarks and may be used in a different manner
to landmarks in a visually impoverished setting [
19
]. Thus, apart from specialized
applications such as training for evacuation during a fire, a rich visual scene is
essential for ecological validity.
The paths people navigate in VEs and the real world often involve many nav-
igational decisions. By contrast the paths used for some navigation research, par-
ticularly studies that investigate low-level mechanisms such as distance perception
and path integration, are simplistic and so may engage different cognitive processes
(e.g., working vs. long-term memory) and brain regions [
20
] than when users nav-
igate in a real VE application. Most experimental studies only expose a participant
once to an environment before testing, which has similarities with being a first-time
visitor to a place, but is clearly different from settings that a user visits repeatedly
and develops spatial knowledge of over an extended period of time. In those latter
circumstances a user has more opportunity to learn the layout of the environment as
a whole (survey knowledge).
Lastly, studies adopt a variety of measures, some of which are designed to assess
specific aspects of users' route or survey knowledge, and others that are designed to
assess to ephemeral concepts such as presence. These measures should be considered
in the context of the tasks users perform in a givenVE application before the relevance
of research findings can be judged.
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5.4 The Effect of Body-Based Information
This section reviews the findings of research into the effect of body-based informa-
tion on navigation, and offers explanations for contradictions between some of the
studies' findings. The review attempts to inform: (a) our basic understanding of how
translational versus rotational body-based information affects human navigation,
and (b) simplify the process of applying those findings to VE applications. In terms
