Information Technology Reference
In-Depth Information
Introduction
In many situations advanced 3D visualization and interaction techniques
have been shown to allow users to perform complex spatial tasks more
efficiently than traditional 2D presentations. Also, in geographical
information systems (GIS) the use of 3D visualization appears to be a
natural way to present information in its spatial context [1]. The advanced
device technology needed to accomplish 3D visualizations, such as
stereoscopic displays and 3D head tracking, is meanwhile readily available
at consumer level costs. As a consequence, when building geographical
information systems, the graphical design is likely to be influenced by
intuition and technical finesse. However, this process should be guided by
an understanding of the kind of tasks that benefit from the possibilities
offered by 3D visualization [2][3].
This chapter gives a brief background to 2D and 3D geo-visualizations
and defines the terminology used in the experimental studies described in
this chapter and elsewhere in the literature. Two experiments are then
presented which aim to compare the value of 2D and 3D visualizations for
the assessment of quantitative information in a geographic context and to
analyse potential effects based on other factors in the studied population.
To that end, spatial tasks with different levels of difficulty are investigated.
One fundamental task in reading maps is the estimation of distances
between geographic positions. Given a number of locations on a 2D map,
identifying the two closest positions is a matter of relative (comparative)
assessment of many distances rather than metrically exact retrieval of an
absolute quantity. From everyday experience in reading documents it
seems self-evident that humans solve this kind of relative spatial
assessment task reliably, regardless if looking straight upon the map or if
viewing the map from some slant angle. On the other hand one would also
expect that reading a map would be hampered due to projective distortion
at extreme slant angles, even if all possible visual 3D cues are available.
The objective of the first experiment described in this chapter is to find
out if 3D representations of a map which is virtually tilted at different
angles will affect users' capability to perform elementary spatial tasks. In
this experiment, the comparative assessment of distances in a map is
studied. The degree of difficulty of the task was systematically varied to
establish the thresholds for reliable completion of this task.
In the second experiment, a more complex spatial assessment task has
been chosen to find out whether advanced 3D visualizations of information
on a map can contribute to improving users' capability to solve the task
compared with using a conventional 2D visualization of the same
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