Game Development Reference
feedbacks: head-mounted displays, natural vision and natural vision with limited
field of vision. The results particularly show an important difference between
actual walking and the other means of movement, which must be studied more
The perception of vection: this is a phenomenon of illusion making us feel move-
ment without moving. This phenomenon is, for example, felt when seated in a
stationary train when the neighbouring train moves. It can be interesting to use
it for simulating movements, or as an addition to other modes of movement. Its
use, however, requires a good understanding of the phenomenon and the differ-
ent parameters that come into the picture. Riecke et al. (2005) conducted several
psychophysical tests on the subject and showed that certain visual details like
expressions can magnify the illusion. The same applies in the case of addition of
several coherent sensory feedbacks.
The field of 3D interaction is relatively new and yet to be developed. Everything seems
to suggest that unlike 2D only a single solution will be accepted, however techniques
may change according to the user, the application, the set-up, etc. This raises problems
of selection criterion for the solution to be implemented, where the significant need
for assessments is currently very rare.
12.5 SELECTION AND MANIPULATION
Touching, gripping and manipulating objects are the first means that man uses to act
in his physical environment. Manipulating objects is an action particularly integrated
by the brain. We carry out complex movements even without realising it, like grabbing
a moving object or maintaining its balance. In the real world, gripping an object is
done directly with the hand and all the senses are available for helping the movement
(particularly vision, touch and hearing). In a virtual environment, the perception of the
environment and the modes of action are less enhanced and depend on many factors:
hardware interfaces used: we do not have the same perception of the environment
when a single-click mouse, an electromagnetic sensor or a wired glove are used.
On the other hand, visualisation on big screens, stereoscopic vision, following
head movements contribute towards better immersion in the virtual environment
and therefore influence the manner of acting in it.
the type and mode of sensory feedbacks: the overlap of virtual and real spaces
(direct or remote manipulation) (Paljic et al., 2002), simulation in real time and the
presence of audio and tactile feedbacks are among the many factors contributing
to the quality of the feeling of immersion.
special conditions of the environment and of the task: objects can be located at dif-
ferent distances from the user, in particular, beyond hand reach. The size (real and
apparent) and shape of objects determines their ease of selection and manipulation.