Spring embedder preprocessing for WWW visualization

We present a preprocessor for the spring embedder graph drawing method and show its use in speeding up the automatic layout of three-dimensional visualizations of WWW sites. Spring embedding is a widely used method for visualizing the connections in WWW maps, as it can typically produce a reasonable layout for most general graphs. However, the technique does not scale well and to improve the performance when dealing with large graphs various optimisations have been developed. Our preprocessor is a new optimization method that attempts to obtain a reasonably good initial drawing to be then used by the spring embedder. This initial drawing has edge lengths that are approximately equal along with a minimum node separation. This produces a layout that is closer to the final drawing than a random scattering of nodes and so allows fewer invocations of the spring embedder to produce an equally stable drawing.