Game Development Reference
In-Depth Information
brain to accept these discrepancies. And only then can you program a VR software
package, not before!
Chronological summary of the design approach:
Step 1: Determination of functional I 2 ;
Step 2: Determination of the necessary VBPs on the basis of the functional I 2 ;
Step 3: Designing the Behavioural Interfaces on the basis of the VBPs (IBS, meta-
phors with or without substitution, artefacts, stimulated senses and motor
responses);
Step 4: Designing the BSAs based on the BIs;
Step 5: Designing the VR software (programming the BSAs, drivers of BIs and
modelling the virtual environment). Designing the software is an important part
and takes a long time, especially for modelling the virtual environment. But this
does not mean that you can neglect or even delete the previous steps!
The choice of an IBS or a metaphor is thus very important in the design phase
and must be examined very carefully. As explained earlier, the schemas used in vir-
tual reality are more or less off the norm, “altered'' compared to the corresponding
schemas, used in the real world. The schemas are more altered if the sensory feed-
back is partial, false or does not exist. For example, while handling a product in a
virtual shop, the sensory feedback is altered by keeping it partial (there is no force
feedback; the weight and inertia of the product do not exist). The schemas used must
be assimilated and familiar for the group of users concerned (children, professionals,
etc.) In any case, the schemas used should cancel out the sensorimotor discrepancies,
which is possible if these discrepancies are not too high (like in the previous exam-
ple). These discrepancies create a major problem for the sensorimotor and cognitive
I 2 . The perceptive phenomena are completely subjective and every person interprets
a particular sensation with reference to whatever he has learnt from his experiences.
These experiences can be very useful in certain applications or can also prove to be
a hindrance for the user in certain cases. Let's imagine an immersive cinema with a
total field of view (360 ) 6 : The spectators immersed visually in a scene react physi-
cally as per their past experiences. If a rapid descent of a twisting road is shown on
screen, the spectators will lean their body to react to the movements that are in fact
nothing but virtual! This happens even though their internal ears tell them that there
is no inclination. Some people can feel some discomfort, which in fact goes against
the set goal - achieving a better immersion. The designer of the virtual reality system
should therefore consider individual reactions which might be different from what he
expects. This conflict between two sensory signals can also cause greater uneasiness.
“Locked'' in a head-mounted display, the user no longer has a visual reference point
in real space, but he can still feel the verticality of this space through the vestibular
systems of his internal ears. The virtual space observed no longer corresponds to the
real space and this can cause uneasiness similar to seasickness. Study of sensorimotor
discrepancies and the brain's neurophysiological adaptation to these discrepancies are
open problems in the field of virtual reality. Experts in neurophysiology and cognitive
6 Even though it does not involve any virtual reality technique as there is no interaction.
 
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