Fekete, J., Wang, D., Dang, N., Aris, A., Plaisant, C. (August 2003)
Every graph can be decomposed into a tree structure plus a set of remaining edges. We describe a visualization technique that displays the tree structure as a Treemap and the remaining edges as curved links overlaid on the Treemap. Link curves are designed to show where the link starts and where it ends without requiring an explicit arrow that would clutter the already dense visualization. This technique is effective for visualizing structures where the underlying tree has some meaning, such as Web sites or XML documents with cross-references. Graphic attributes of the links such as color or thickness can be used to represent attributes of the edges. Users can choose to see all links at once or only the links to and from the node or branch under the cursor.