Interactive visualization of genealogical graphs

The general problem of visualizing "family trees", or genealogical graphs, in 2D, is considered. A graph theoretic analysis is given, which identifies why genealogical graphs can be difficult to draw. This motivates some novel graphical representations, including one based on a dual tree, a subgraph formed by the union of two trees. Dual trees can be drawn in various styles, including an indented outline style, and allow users to browse general multitrees in addition to genealogical graphs, by transitioning between different dual tree views. A software prototype for such browsing is described, that supports smoothly animated transitions, automatic camera framing, rotation of subtrees, and a novel interaction technique for expanding or collapsing subtrees to any depth with a single mouse drag