Game Development Reference
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Figure 1. The Activation-emotion space.
VERY ACTIVE
FEAR
SURPRISE
Irritated
Panicky
Pleased
Eager
Amused
Hopeful
Antagonistic
ANGER
C heerful
JOY
Resentful
C ritical
Content
Possesive
VERY
NEGATIVE
VERY
POSITIVE
Suspicious
Serene
Depressed
Delighted
Despairing
Contemptuous
DISGUST
ANTICIPATION
Trusting
Bored
Gloomy
SADNESS
ACCEPTANCE
Calm
VERY PASSIVE
circle. Plutchik has offered a useful formulation of that idea, the “emotion wheel”
(see Figure 1).
Activation-evaluation space is a surprisingly powerful device, which is increas-
ingly being used in computationally oriented research. However, it has to be
noted that such representations depend on collapsing the structured, high-
dimensional space of possible emotional states into a homogeneous space of two
dimensions. There is inevitably loss of information. Worse still, there are
different ways of making the collapse lead to substantially different results. That
is well illustrated in the fact that fear and anger are at opposite extremes in
Plutchik's emotion wheel, but close together in Whissell's activation/emotion
space. Thus, extreme care is needed to ensure that collapsed representations are
used consistently.
MPEG-4 Based Representation
In the framework of MPEG-4 standard, parameters have been specified for
Face and Body Animation (FBA) by defining specific Face and Body nodes in
the scene graph. MPEG-4 specifies 84 feature points on the neutral face, which
provide spatial reference for FAPs definition. The FAP set contains two high-
level parameters, visemes and expressions. Most of the techniques for facial
animation are based on a well-known system for describing “all visually
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