SpaceTree: Supporting Exploration in Large Node Link Tree, Design Evolution and Empirical Evaluation Catherine Plaisant, Jesse Grosjean, Benjamin B.Bederson in Proceedings of IEEE Symposium on Information Visualization, 2002: , Boston, October 2002 Presented by Mei Huang & Chunyuan Liao 3/10, 2005

Outline Motivation Related work Highlights of SpaceTree Controlled Experiments CommentsDiscussions

Motivation Improve classic tree representation (node link diagram) by zoomable UI and animation techniques Classic representation is the most familiar mapping of a tree Classic representation is the most familiar mapping of a tree Inefficient space usage makes large tree exploration not so convenient Inefficient space usage makes large tree exploration not so convenient Zooming & animation can improve user experiences Zooming & animation can improve user experiences

Related work (1) Category 1 : Space filling Representatives RepresentativesTreemaps Information slices Comments Comments Focus on leaf nodes, not the tree topology Users need training due to unfamiliarity

Information Slices

Related work (2) Category 2 : Node link Techniques Techniques Layout : V/H hierarchy, Circular layout (hyperbolic tree), 3D diagram V/H hierarchy, Circular layout (hyperbolic tree), 3D diagram Uneven scaling : Overview + Detail views, Zooming, Pruning, Expand & Contract Overview + Detail views, Zooming, Pruning, Expand & Contract Selective rendering : Dynamic Query Dynamic Query Comments Comments Clearer and intuitive view of tree topology Challenge in screen space usage

Highlights & Early Design lessons Semantic zooming Aggressive expanding Decomposed tree animation Landmark Search & Filter Demo

Hyperbolic Browser Lay a whole tree out in a hyperbolic plane and map it to a unit disk Focus & context Smooth & continuous animation John Lamping, Ramana Rao, and Peter Pirolli “A Focus+Context Technique Based on Hyperbolic Geometry for Visualizing Large Hierarchies” Processdings of the ACM SIGCHI Conference on Human Factors in Computing Systems, Denver, May 1995 Circle Limit IV by M.C. Escher Demo

Comparing SpaceTree, Hyperbolic Tree Browser, MS Explorer, and Treemap Task type Task examples Applications STHTEpTM Node location Find max/min on some attribute ---+ Find a specific node by title ++-+ Visiting history Locate visited nodes ---- Topology question Quick overview ++-- Compare 2+ branches ---- List ancestors +--- Find braches with 10+ children -+-- Compare branch size +--- Compare subtree depth +---

Comments A good application of zoomable UI & animation Early version review provides very useful information Controlled experiments were carefully designed; observation explanations were clear and sound Screen space usage could be improved

Discussions Checking available space in both dimensions? Alternative summarizers Label several previously visited paths may be useful How to deal with large node bounding box? Combining ST with HT?