HTV-Beschreibung

"Hyperbolic graph layout uses a context + focus technique to represent and manipulate large tree hierarchies on limited screen size. Hyperbolic trees are based on Poincare's model of the (hyperbolic) non-Euclidean plane. Experience non-Euclidean Geometry with Paul Garrett's applet! John Lamping, Ramana Rao and Peter Pirolli rediscovered hyperbolic spaces in 1995 for information visualization. Tamara Munzner at Stanford University developed a 3D hyperbolic viewer in her Ph.D. thesis.

The hyperbolic layout employs the following techniques:

• Radical Layout: Conventionally, trees are displayed on a Euclidean plane with the root at the top and children below their parents and connected to their parents with edges. The hyperbolic layout uses a radical layout. The root is placed at the center while the children are placed at an outer ring to their parents. The circumference jointly increases with the radius and more space becomes available for the growing numbers of intermediate and leaf nodes.
• Distortion Technique: Hyperbolic layout uses a nonlinear
  (distortion) technique to accommodate focus and context for a large number of nodes.
• Non Overlapping:To ensure that nodes do not overlap each other, hyperbolic layout algorithms assign an open angle for each node. All children of a node are laid out in this open angle.
• Refocusing: Transformations are provided to allow fluent node repositioning. Users can click on a node to move it to the center or to grab and reposition a single node."

(Quelle @ 20040531.00-56, Abschnitt "Description")