Skeletal animation is a concept that has been used in the areas of motion pictures and computer games to create realistic motion for the animation of articulated characters. Recent work (Merrick & Dwyer 2004, Murray et al. 2004) has applied skeletal animation techniques from inverse kinematics and dynamics to the field of graph interaction. The motivation for this paper is to evaluate the dynamicsbased technique in terms of its ability to simulate the skeletal metaphor, and to evaluate the skeletal metaphor in terms of its usefulness for graph interaction. We conduct a user-based evaluation for this purpose. The results of which confirm the usefulness of both the dynamics-based technique and the skeletal metaphor in aiding the users understanding of a graph. Keywords: Graph Interaction, Skeletal Animation, User-based Evaluation 1

We describe a new technique for graph layout subject to constraints. Compared to previous techniques the proposed method is much faster and scalable to much larger graphs. For a graph with n nodes, m edges and c constraints it computes incremental layout in time O(nlogn + m + c) per iteration. Also, it supports a much more powerful class of constraint: inequalities or equalities over the Euclidean distance between nodes. We demonstrate the power of this technique by application to a number of diagramming conventions which previous constrained graph layout methods could not support. Further, the constraint-satisfaction method—inspired by recent work in position-based dynamics—is far simpler to implement than previous methods.