Simulation levels of detail for control and animation

Physical simulation is a powerful technique for animating characters in interactive environments, video games, and off-line simulations. The characters in these applications must demonstrate a variety of complex and interesting behaviors and must be responsive to the user's actions. Although simulated characters interact with users in physically realistic ways, they are difficult to control and are computationally expensive. In this thesis, I address this problem by developing a technique called simulation level of detail, in which a simplified version of a character is used as a stand-in for the fully simulated character in both control and animation algorithms. When used for navigation control, simulation levels of detail provide approximations of a character's dynamic abilities, which encapsulate the movements and actions a character can perform. When used to create efficient animation, simulation levels of detail approximate a character's movements and reduce the animation costs of characters that are less important to the user or to the action in the graphical environment. The success of these techniques is demonstrated by a suite of control and animation experiments. Through automated off-line experimentation, I created simplified versions of human and alien bicyclists that serve as simulation levels of detail in the navigation tasks: individual trajectory tracking, group formation, and group trajectory tracking. Analysis of the characters' performances indicates that navigation controllers augmented with simulation levels of detail produce smaller tracking errors, faster group formation, and improved tracking stability. The simulated human bicyclist and its simplified counterpart were also used to develop simulation levels of detail for a reduced-computation bicyclist character. During trajectory tracking experiments, this character reproduces the general movements of its fully simulated counterpart while significantly reducing computational requirements.