Graphical level of detail (LOD) is a set of techniques for coping with the issue of limited computational resources by reducing the graphical detail of the scene far from the observer. Simulation LOD reduces quality of the simulation at the places unseen. Contrary to graphical LOD, simulation LOD has been almost unstudied. As a part of our ongoing effort on a large virtualstorytelling game populated by tens of complex virtual humans, we have developed and implemented a set of simulation LOD algorithms for simplifying virtual space and behaviour of virtual humans. The main feature of our technique is that it allows for several degrees of detail, i.e. for gradual varying of simulation quality. In this paper, we summarise the main lessons learned, introduce the prototype implementation called IVE and discuss the possibility of scaling our technique to other applications featuring virtual humans.

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Abstract. Model checking tools based on the iterative refinement of predicate abstraction (e.g., Slam and Blast) often feature a specification language for expressing complex behavior rules. The source code under verification is instrumented by artificial variables and statements in order to transform the problem of checking such a rule into the problem of program location reachability. This way, the source code get bloated and additional predicates have to be discovered and tracked during the verification. We suggest that a significant performance improvement can be achieved by tracking state of the behavior rules aside from the source code instead of instrumenting them. We have implemented an extension to Blast, which accepts a specification language (a simplified version of behavior protocols), and checks its validity without modifying the input source code. An experiment with two Linux kernel drivers confirms the performance gain using the extension.

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