Improved Force-Directed Layouts
Techniques for drawing graphs based on force-directed placement and virtual physical models have proven surprisingly successful in producing good layouts of undirected graphs. Aspects of symmetry, structure, clustering and reasonable vertex distribution arise from initial, formless clouds of points. However, when nodes must be labeled and point vertices are replaced by non-point vertices, simple force-directed models produce unreadable drawings, even for a moderate number of nodes. This paper describes the application of two post-processing techniques that can be applied to any initial vertex layout to produce uncluttered layouts with non-point nodes.