Game Development Reference
Figure 12.1 Milling training simulator. (Illustration: Clarté, with permission)
the head movements are limited to less than 180 ◦ horizontally and to less than 90 ◦
the head movements are horizontally and vertically more sizeable than in the
the observation is focused on a small fixed zone of the virtual environment, the
view point of the observer could revolve around this zone.
In the first case, a computer screen suffices if the space is small, as in a milling
training simulator (Figure 12.1), see the chapter on the PERF RV project. If the space
is large and must be viewed to scale 1, a large screen with video projection is necessary.
In the second case, if there is only one observer, several visual interfaces are pos-
sible: triple screens, small visual enclosure or visual room (immersive room), as in the
driving simulator (Figure 12.2), see the chapter on the PERF RV project. If there are
several observers, only the last two types of interfaces are possible.
In the third case, the interface to be used is the head-mounted display, except if the
resolution is not sufficient or if the port of the head-mounted display is restrictive for
the observer. If a head-mounted display cannot be used, using a visiocube is possible
if the cost is not prohibitive, like in Clarte's SAS cube (Figure 12.3); see the chapter
on the PERF RV project. Otherwise, using a single screen (monitor or big screen) is
workable with a tracker connected to the observer's head.
A BSA for increasing the field of vision should be carefully chosen so that it can
be used effectively. For example, when the user turns his head at an adequate angle
in relation to the normal screen angle, the viewpoint also turns (the centre of rotation
is located at the level of the user's head). The rotational speed is either fixed or is
proportional to the angle of rotation. This is workable only after a learning period
that is not too long. But orientation in the virtual world can cause a problem.
In the fourth case, an immersive window can be suitable, if the hands of the user
are free. Otherwise, a screen with a tracker on the head can be used. If it is only