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CHAPTER 4
Simulating Visual Attention for
Crowds
The experiments we have conducted in the context of social phobia, that will be discussed
in detail in Chapter 6, have underlined the crucial importance of eye contact in human communication.
In order to obtain believable and natural looking crowd characters, we thus
decided to endow them with attention behaviors. We developed an architecture applicable
to both social phobia and agoraphobia with crowds, in the sense that it can be applied to a
single or small number of characters but also to a large crowd of characters. This architecture
allows for characters to behave naturally in terms of gaze behaviors and to perform looking
motions in a smooth and natural way.
When we walk in town, we pay attention to our surroundings by looking in different
directions. We look at other people, objects, or even at nothing in particular. As mentioned,
we believe that an important aspect which can greatly enhance crowd animation realism is
for the characters to be aware of their environment and of other characters. This has partly
been achieved with navigation and path planning algorithms. Our aim, however, is to obtain
more advanced behaviors than those which navigation alone can provide. This raises the
common problem of mandatory trade-off between rich, realistic behaviors and computational
costs. Individual character animation may provide realistic results but is computationally
expensive. Conversely, global crowd behavior design is much faster but results in a loss of
character individuality. To add gaze attention behaviors to crowds, we are confronted with
two issues. The first one is to detect the points of interest for characters to look at. The
second one is to edit the character motions for them to perform the gaze behavior. This has
to be done very rapidly in order to animate a large number of characters. In this chapter, we
propose a two-fold method which meets all these requirements.
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