Hierarchical animation control of avatars in 3-D virtual environments

This paper reports the development of a three-layer hierarchical control system for the animation of anthropomorphic avatars in three-dimensional virtual environments. The lower layer controls the movement of the avatar´s joints, the second layer defines skills or basic behaviors (such as walk, run, and jump), and the highest layer executes a behavior-based script language that can be used to describe stories to be enacted by the avatars. In order to verify how flexible the proposed hierarchical approach is, the two lower control layers were implemented in two different ways, without affecting the script language layer.