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Tiered Behaviour Architecture for Virtual Characters using Cyclic Scheduling and Behaviour Capture Open Access


Other title
cyclic scheduling
Non-Player Character
Hidden Markov Models
Behaviour Capture
virtual character
Type of item
Degree grantor
University of Alberta
Author or creator
Zhao, Richard
Supervisor and department
Szafron, Duane (Computing Science)
Examining committee member and department
Riedl, Mark (School of Interactive Computing, Georgia Institute of Technology)
Bowling, Michael (Computing Science)
Mueller, Martin (Computing Science)
Gouglas, Sean (History and Classics)
Szafron, Duane (Computing Science)
Department of Computing Science

Date accepted
Graduation date
Doctor of Philosophy
Degree level
A story-based video game contains many characters. A few are controlled by the player and the majority are virtual characters, controlled by artificial intelligence. In recent years, video game artificial intelligence has developed slower than other aspects of video games, such as graphics, mainly due to the cost of scripting complex and believable virtual characters. To tackle this bottleneck in content creation, several behaviour architectures have been proposed over the past decades. This dissertation proposes metrics for evaluating behaviour architectures and their associated toolsets: expressiveness, performance, quality, and usability. A good mechanism for evaluating architectures / toolsets is essential to replace the current trial and error approach that is in practice today. This dissertation also proposes a new Tiered Behaviour Architecture model and its associated toolset for controlling the behaviours of virtual characters, and evaluates it by applying the metrics. The objective (top) level of the architecture determines the general schedules of the virtual characters composed of objectives, and the roles that will accomplish these objectives. Cyclic scheduling is a technique that allows for the automatic generation of schedules based on partially specified constraints. The role (bottom) level of the architecture uses Behaviour Capture with Hidden Markov Models, a self-contained technique, to generate actual fine-grained behaviours. This dissertation presents studies that show behaviours generated by this architecture / toolset have high scores for all four metrics. It also shows that Behaviour Capture with Hidden Markov Models generates higher quality (more believable) behaviours for virtual characters than the state of the art in commercial games.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
R. Zhao and D. Szafron. Using Cyclic Scheduling to Generate Believable Behavior in Games. Proceedings of the Tenth AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment (AIIDE-14), Raleigh, North Carolina, October, 2014, p94-101.R. Zhao and D. Szafron. Virtual Character Behavior Architecture using Cyclic Scheduling. Proceedings of the 9th International Conference on the Foundations of Digital Games (FDG 2014), Fort Lauderdale, Florida, April, 2014.R. Zhao and D. Szafron. Generating Believable Virtual Characters Using Behavior Capture and Hidden Markov Models. Proceedings of Advances in Computer Games 13 Conference (ACG), Tilburg, The Netherlands, November, 2011, Lecture Notes in Computer Science 7168, Springer 2012, p342-353.

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