Herman, IvanDelest, MaylisMelancon, Guy2015-02-152015-02-1519981467-8659https://doi.org/10.1111/1467-8659.00235Information visualisation often requires good navigation aids on large trees, which represent the underlying abstract information. Using trees for information visualisation requires novel user interface techniques, visual clues, and navigational aids. This paper describes a visual clue: using the so-called Strahler numbers, a map is provided that indicates which parts of the tree are interesting. A second idea is that of "folding" away subtrees that are too "different" in some sense, thereby reducing the visual complexity of the tree. Examples are given demonstrating these techniques, and what the further challenges in this area are.10.1111/1467-8659.00235153-165