Creating Believable and Effective AI Agents for Games and Simulations: Reviews and Case Study

Creating Believable and Effective AI Agents for Games and Simulations: Reviews and Case Study

Iskander Umarov (TruSoft International Inc., USA) and Maxim Mozgovoy (University of Aizu, Japan)
DOI: 10.4018/978-1-4666-6252-0.ch003
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The rapid development of complex virtual worlds (most notably, in 3D computer and video games) introduces new challenges for the creation of virtual agents, controlled by Artificial Intelligence (AI) systems. Two important sub-problems in this topic area that need to be addressed are (a) believability and (b) effectiveness of agents' behavior (i.e. human-likeness of the characters and high ability to achieving their own goals). In this chapter, the authors study current approaches to believability and effectiveness of AI behavior in virtual worlds. They examine the concepts of believability and effectiveness and analyze several successful attempts to address these challenges. In conclusion, the authors provide a case study that suggests that believable and effective behavior can be achieved through learning behavioral patterns from observation with subsequent automatic selection of effective acting strategies.
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What is a Virtual World?

Virtual worlds provide a basis for many popular video and computer games (e.g. Half-Life, The Sims), “life simulators” (e.g. Second Life, Entropia Universe), and virtual military training grounds (e.g. Virtual Battle Space). The use of such worlds becomes more and more widespread, as typical hardware is now able to perform realistic 3D real-time rendering, and the coverage of broadband Internet connection constantly increases. Furthermore, virtual worlds get new applications, most notably in the area of education and “serious games.” One can note, for instance, the existence of “virtual classrooms” in Second Life.

It is interesting to note that while the term “virtual world” is commonly used, only few authors provide its precise definition. Bell (2008) tried to combine previous definitions, found in the literature, into the following formula: “a synchronous, persistent network of people, represented as avatars, facilitated by networked computers.” This definition, though, ignores an important observation: modern virtual worlds can be inhabited not only with human-controlled characters, but also with AI-based virtual agents, serving as non-participating world’s “native population,” hostile opponents or friendly teammates. Furthermore, it is still unclear what kinds of computer-generated environments qualify for the name of “virtual worlds.” The work by Mitchell (1995) “From MUDs To Virtual Worlds” suggests a clear distinction between MUDs (Multi-User Dungeons, text-based multiplayer games) and virtual worlds. Mitchell notes the lack of immersion, caused by limited visual capabilities of MUDs, and suggests that virtual worlds should combine MUD-styled gameplay with vivid 3D graphics. Though the discussion of features that turn a virtual simulation into a virtual world are beyond the scope of this chapter, it is natural to presume that “a world” should possess certain high degree of complexity and audiovisual interaction, not found in simpler computer-simulated environments.

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