1 SIMS 247: Information Visualization and Presentation jeffrey heer Tree Visualization Oct 26, 2005

2 today administrivia tree visualization design exercise

3 administrivia How are project proposals coming along? If you have questions, concerns, or are seeking advice, come to my office hours!! –Today, 1-2:30pm South Hall –Appointments also possible

4 Graphs and Trees Graphs: –Representations of structured, connected data –Consist of a set of nodes (data) and a set of edges (relations) Trees: –Graphs with a specific structure connected graph with n-1 edges –Representations of data with natural hierarchy –Nodes are either parents or children

5 Tree Visualization File Hierarchy in computer Need to navigate through the hierarchy to find a particular file Two common problems: “Where am I?” and “Where is the file that I am looking for?”

6 Tree Visualization Organizational Chart

7 Tree Visualization Tournaments taken from “To Draw A Tree” by Pat Hanrahan

8 Tree Visualization Family Trees taken from “To Draw A Tree” by Pat Hanrahan

9 Tree Visualization Family Trees taken from “To Draw A Tree” by Pat Hanrahan

10 Tree Visualization Evolutionary Trees taken from “To Draw A Tree” by Pat Hanrahan

11 Tree Visualization Evolutionary Trees taken from “To Draw A Tree” by Pat Hanrahan

12 Tree Visualization Assembly Instructions taken from “To Draw A Tree” by Pat Hanrahan

13 Tree Visualization Approaches Node-Link Diagrams –Reingold-Tilford Layout –Radial Layout –Indented Layout –Cone Trees & Balloon Trees –Hyperbolic Trees Enclosure Diagrams –TreeMaps –Voronoi TreeMaps –Jigsaw Maps Alternative Approaches –Icicle Trees –Sunburst Diagrams –Cascaded Lists

14 Top-down layout Uses separate dimensions for breadth and depth breadth --> width depth --> height Reingold-Tilford Layout tidier drawing of trees - reingold, tilford

15 Radial Layout Places children on increasing larger radii A top-down layout converted into polar co-ordinates breadth --> angle depth --> radius gnutellavision – yee, fisher, dhamija, hearst

16 Indented Layout Places all items along vertically spaced rows Uses indentation to show parent child relationships Breadth and depth end up fighting for space resources breadth --> height, locality depth --> height, indentation microsoft file explorer

17 Cone Trees Top-down tree layout in three dimensions Shadows provide 2D structure Can also make “Balloon Trees” – 2D version of ConeTree cone tree – robertson, mackinlay, and card

18 Balloon Trees flattened cone trees herman, melancon, and marshall

19 Hyperbolic Trees Places nodes using hyperbolic geometry This is then projected into “normal” space hyperbolic tree – lamping, rao h3 viewer – tamara munzner

20 TreeMaps Space-filling technique that divides space recursively Segments space according to ‘size’ of children nodes map of the market – wattenberg / smartmoney.com

21 Voronoi TreeMaps TreeMaps that divide space using arbitrary polygons based on Voronoi tesselations. voronoi treemaps - balzer and deussen

22 Jigsaw Maps Space-filling technique from Martin Wattenberg - a mathematical experiment at trying to achieve a “perfect” layout. Uses the mathematics of space-filling curves. jigsaw maps - martin wattenberg

23 Icicle Trees Edges implied by adjacency and spatial relationship. icicle tree in the infovis toolkit - jean-daniel fekete

24 Sunburst Diagrams Radial version of icicle trees. sunburst diagram - john stasko

25 Cascaded Lists Display one selected group of silbings at a time Mac OS X File System Browser

26 More advanced trees… We can augment the approaches we’ve seen so far with additional visualization and interaction techniques. Some examples: Degree-of-Interest Trees / SpaceTree –top-down node-link diagrams with focus+context Elastic Hierarchies –node-link diagrams crossed with treemaps Dual Trees –bi-directional top-down node-link diagrams –developed for genealogical graphs

27 degree-of-interest trees doitrees - heer, card

28 elastic hierarchies hybrid of node- link diagrams and treemaps elastic hierarchies - zhao, mcguffin, chignell

29 dual-trees a bidirectional tree visualization designed for navigating genealogical graphs (family “trees”) dual-trees - mcguffin, balakrishnan

30 So what technique to use? A cautionary tale: –CHI Browse-off and evaluation of the hyperbolic tree –What makes the difference: the car or the driver? Reading –People read faster by scanning in lines (not arcs!) Convention –Does your application domain have established conventions? How can you leverage or augment those? Designs with multiple visual components –How much screen real-estate do you give the tree? –(Sometimes that indented tree works the best!)

31 Design Exercise Brainstorm new visualizations for family “trees” Choose an aspect *NOT* covered by current designs Here are some of the complications to consider: –People as individuals / Couples as reproductive units –Ordering by Generation vs. Time –Divorce/Death/Remarriage –Polygamy –Incest (!) –Social vs. Biological lineages? Think of important questions a visualization should answer, use them to motivate the design –Are two people related? In how many ways? Work in groups of 3 or more. You will be asked to briefly present your ideas to the class on Monday!

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