Opis produktu
Visual navigation of hierarchically structured graphs is a technique for
interactively exploring large graphs with an additional hierarchical structure
such as call graphs of telephone networks. In order to reduce the complexity
of the graph, only the interesting subgraphs are shown in detail, while the
others are collapsed. As the areas of interest change over time, clusters are
expanded or contracted, for which an efficient data structure is needed. In
this work a new variant of this problem is introduced, which supports
insertion and deletion of graph nodes. So far efficient data structures were
known only for more static variants. The proposed data structure builds on a
novel technique of superimposing a search tree over an ordered list maintenance
structure. For visualizing the expanding and contracting a local
update scheme for the well-known algorithm of Sugiyama and Misue is
presented, which has applications ranging from UML diagrams to biochemical
pathways. Experimental results show that this update scheme is
more efficient than redrawing, yet the performance gain is not at the expense
of quality as regards the area of the drawing and the number of crossings.