Information Visualization:Trees

Chris Northcs3724: 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

• ResultSet -> 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• node & link• E.g. TreeView widget

• Containment• node in node• E.g. Venn diagram

A

CB

A

B C

Detail Only

• Dos: tree

• Whats the problem?

TreeView 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

3D• ConeTrees

• Rotate subtrees

• Pro:•

• Con:•

• Xerox PARC

Ugh!

2 Approaches

• Connection• node & link• E.g. TreeView widget

• Containment• node in node• E.g. Venn diagram

A

CB

A

B C

Zooming• TreeMaps

• 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/treemap3/

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

Cushion TreeMaps• Cushion TreeMaps

• Free file directory browser• Van Wijk • http://www.win.tue.nl/sequoiaview/

• Map of the Market• http://www.smartmoney.com/marketmap/

Radial Containment• SunBurst

• 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