Artificial Mind for Virtual Characters - Advancing Artificial Intelligence Through Biological Process Applications - page 185

the first is to focus on producing behaviors simi-
lar to those seen in real life, no matter by what
means; the second is to achieve believability by
using plausible mechanisms to generate character
behavior. While the former just tries to imitate
real behavior, the latter goes further, trying to
simulate scientific models of behavior, mind
and/or brain. Between those approaches, a range
of rigorousness in applying those models may
exist, going from not taking them into account,
to attempts to strictly implement them. Next, the
two approaches are discussed regarding their use
of Artificial Intelligence techniques.

cooking and the microwave oven broadcasts that
it can cook food. So, the character next action is
to put the food in the oven. The characters just
have to walk around in their world and manage
their needs priorities. They don't have anything
like a “mind” or “brain” structure.
In PetroSim Project (Musse, Silva, Roth, Hardt,
Barros, Tonietto, and Borba, 2003; Barros, Silva,
and Musse, 2004), also, the characters' structure
does not contain all the information they need
to choose their next action. A module extracts
environment information from the 3D model
of the virtual world and stores it on a database.
The automatic reading of the geometric model
provides elements like streets, houses, etc., and
then a hierarchical tree is built based on this in-
formation. User-defined attributes may be added
to the tree, if they are considered relevant to the
application (such as risk areas, for example). When
characters need information about the world they
search it on the database, instead of obtaining it
directly from the environment. Even knowledge
about the characters themselves, like psychologi-
cal profile (leader, dependent, etc.), along with
some information about the environment (such
as daytime, possible accidents, etc.), is stored in
the database. The purpose of this approach is to
decrease the real-time processing, especially in
the case of crowded virtual worlds.
The problem with this smart environment
approach is that it doesn't leave much room for
character idiosyncrasies. When action selection
is conducted from outside the character, the re-
sulting behavior tends to be somewhat standard-
ized. After all, the purpose of this technique is
mainly to reduce the complexity of the system.
Also, the character autonomy is decreased, by
definition. According to Merriam-Webster's
Dictionary, autonomy is “the quality or state of
being self-governing”. Many inhabited virtual
environment applications need a high degree of
autonomy, and then a self-contained structure is
necessary to model the characters. Usually the

Smart Environments

When underlying mechanisms of behavior are not
relevant to the application, Artificial Intelligence
techniques may be not restricted to the “living”
entities of the virtual world. Intelligence may be
conveniently distributed in the environment. This
technique may increase the computational effi-
ciency of the whole simulation, especially when
there is a large population of virtual characters.
That is the case, for instance, of the popular
game The Sims® (Schwab, 2004). From the player
perspective, this game is about following and tak-
ing care of specific characters in their everyday
life. Apparently, they are virtual humans with
internal needs, aware of the environment elements
that can fulfill them. However, they are relatively
simple agents responding to messages sent by
objects of the environment that are broadcasting
what they have to offer to nearby characters. These
objects encapsulate the knowledge of which needs
they satisfy and what happens when a character
interact with them (like the correspondent ani-
mations, sound effects and behaviors). This is
called “smart terrain”. The environment guides
the sequence of character actions. If a character
walks close to a refrigerator, the refrigerator
sends a message advertising that it can satisfy
hunger. When the character takes the food from
the refrigerator, the food broadcasts that it needs