The lack of autonomy of keyframed or motion-data driven characters detracts from the modifiability and interactability of the animation. Since realistic behaviors of an animal are subject to the state of its environment (which contains immobile and mobile objects, such as trees, stones, and other animals), slight modifications in a scripted animation, such as moving a tree or adding another animal, may require that the entire animation be re-scripted. Graphical puppets are incapable of actively interacting with their environment. As a result, keyframing techniques are ill-suited to applications such as virtual reality, computer games and interactive educational tools.
| Xiaoyuan Tu | January 1996 |