Game Development Reference
Models for visual rendering
Bernard Péroche, Pascal Guitton and Mathias Paulin
15.1 RENDERING FOR VIRTUAL REALITY
Irrespective of their final use, all virtual reality systems are based on the simulation
of a task using computer resources (calculation, display, interaction, etc.). It can be a
task of exploration, learning, designing, etc. More precisely, it involves providing the
user's brain with information resulting from digital data and simulating the context of
the task to be performed.
The first sense involved is the vision; in fact, a large amount of information used
by the human brain to perceive his environment is of visual nature. It is thus natural
to first focus on visualisation while developing an application of virtual reality. We
will talk about rendering methods to describe the algorithms used to produce this
sensory information. Unfortunately, the complexity of simulation often proves to be a
hindrance in their implementation.
All the information calculated by the algorithms of rendering (visual, haptic, audio)
and taken into account by the user's brain give him a feeling called immersion .Itis
mainly on the quality of this immersion that the “adherence'' depends. Adherence is
the user's belief in the environment that the application reproduces for him, and as a
result, the quality of the task that he has to perform virtually. For example, cinema,
with its highly sophisticated special effects, shows exact reproductions of (real or
virtual) environments, but the spectator remains passive and cannot intervene in the
story. We do not call it virtual reality though the rendering techniques used are very
similar. In other words, a virtual reality application providing an excellent quality of
rendering but very poor interaction mechanisms will not be able to give a good feeling
of immersion to the user. Finally, immersion is achieved from the combined quality of
rendering and interaction.
15.1.2 Real-time rendering
Another fundamental difference between VR applications and cinema comes from
the passive attitude of the spectator: since he does not intervene in the way the film
progresses, it is “possible'' to decide (script, storyboard) and thus film and/or calculate
all the images before projecting. On the other hand, in the case of virtual reality, it is
necessary to produce the rendering as per the demands/actions of the user.