Information Visualization Trees Chris North cs 3724 HCI

Information Visualization: Trees Chris North cs 3724: HCI

Info Visualization Review • Multi-dimensional data vis • Navigation strategies

Trees (Hierarchies) • What is a tree? • • DAG, one parent per node items (can have attributes) + structure Data structure: parent ptr, array of children, LM child+RS Size: #nodes = bheight • Result. Set -> Tree? • categorical • Parent ptr • Path name

Examples • Example trees: • book libraries, folders, family trees, threaded msgs • NCAA march madness!!!! • Aisles, websites, org charts • Tasks: • search, drill down, browsings • Structural analysis, parents, children, • Least common ancestor

2 Approaches • Connection A • node & link • E. g. Tree. View widget • Containment • node in node • E. g. Venn diagram B C A B C

Detail Only • Dos: tree • Whats the problem?

Tree. View Widget • • • Good for directed search tasks Good for text labeled nodes Not good for learning structure No attributes Apx 50 items visible Lose path to root for deep nodes Scroll bar! Error rate high Fitt’s Law? • Too many small distant things

Mac Finder

Overview+Detail • Maryland

Focus+Context • Hyperbolic Tree (star tree) • Radial; shrink with distance to center • Drag to navigate • Scalability? • Xerox PARC, Inxight • http: //startree. inxight. com/

Miniaturization • Disk Tree • Xerox PARC

3 D • Cone. Trees • Rotate subtrees • Pro: • • Con: • • Xerox PARC

Ugh!

2 Approaches • Connection A • node & link • E. g. Tree. View widget • Containment • node in node • E. g. Venn diagram B C A B C

Zooming • Tree. Maps • • Slice and Dice, space filling Node size & color encodes data attribute Zoom on subtrees Good for fixed-height trees • Scalability? • Maryland • http: //www. cs. umd. edu/hcil/treemap 3/

• “Squarified” Tree. Map • http: //www. research. microsoft. com/~masmith/all_map. jpg

Cushion Tree. Maps • Free file directory browser • Van Wijk • http: //www. win. tue. nl/sequoiaview/ • Map of the Market • http: //www. smartmoney. com/marketmap/

Radial Containment • Sun. Burst • Radial slicing • Animated zooming • Focus+Context • Georgia Tech

Sunburst vs. Treemap • + Faster learning time: like pie chart • + Details outward, instead of inward • + Focus+context zooming • - Not space filling • - More space used by non-leaves • All leaves on 1 -D space, perimeter • Treemap: 2 -D space for leaves • - Smaller scalability?

Multiple Foci? • Focus on 2 distant regions simultaneously • Microsoft Research