We have implemented the H3 layout technique as part of the SiteMgr application for web site creation and management from Silicon Graphics. Most of the paper as a whole focuses on the layout algorithm, but this section describes key features of the SiteMgr visualization component.
The SiteMgr system allows interactive navigation of structures which are too large to render in their entirety, by providing explicit gardening controls to expand or contract subtrees. The original PARC cone tree system [RMC91] also used explicit gardening, but this approach is inferior to the automatic subtree expansion and collapse featured in systems such as the PARC 2D hyperbolic browser [LRP95] or Carrière's cone tree extension [CK95]. We do automatically cull text labels when nodes move far from the origin.
The user can also toggle the display of nontree links which enter or leave selected nodes. We distinguish incoming from outgoing nontree links to allow fine-grained control of the display. Nodes like logo images tend to have many incoming links, while table of contents nodes would have many outgoing links. Nodes are colored according to MIME type. The user can choose a different root node for the spanning tree, which will show a very different view of the graph.
When the user clicks on a node, it is selected and undergoes an animated transition to the center of the sphere. In addition to this translational component, the transition includes a rotational component so that when the node reaches the origin its ancestors are on its left while its descendants appear on the right. This butterfly representation serves to orient the user and to minimize occlusion of both nodes and their text labels. In the terminology of the original PARC paper [RMC91], we have chosen the horizontal cam trees orientation instead of the vertical cone tree orientation. If the user clicks on an edge, that point is translated to the center of the sphere but no rotation or selection occurs.
The SiteMgr system was designed and tuned for web site visualization. However, it is possible to import graphs into the hyperbolic viewer that were created from other kinds of data, which is how the Unix filesystem and function call graph figures in this paper were made.