Behavioural animation of virtual humans: what kind of laws and rules ?

Interactive systems, games, VR and multimedia systems require more and more flexible Virtual Humans with individualities. Behavioral animation seems to be the best way to develop this kind of applications, but there is still a major problem to select the right laws and rules to implement individual but believable behaviors. To create motion laws, there are mainly two approaches: 1) Recording the motion using motion capture systems, then to try to alternate such a motion to create this individuality. This process is tedious and there is no reliable method at this stage. 2) Creating computational models which are controlled by a few parameters. One of the major problem is to find such models and to compose them to create complex motion. Such models can be created for walking, grasping, but also for groups and crowds