SIMS 247 Information Visualization and Presentation jeffrey heer

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

today • administrivia • tree visualization • design exercise 2

administrivia • How are project proposals coming along? • If you have questions, concerns, or are seeking advice, come to my office hours!! – Today, 1 -2: 30 pm - 210 South Hall – Appointments also possible 3

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 4

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? ” 5

Tree Visualization • Organizational Chart http: //www. cs. umd. edu/hcil/spacetree/ 6

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

Tree Visualization • Family Trees 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 • Evolutionary 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 • Assembly Instructions taken from “To Draw A Tree” by Pat Hanrahan 12

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

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

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 15

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 microsoft file explorer breadth --> height, locality depth --> height, indentation 16

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

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

Hyperbolic Trees Places nodes using hyperbolic geometry This is then projected into “normal” space h 3 viewer – tamara munzner hyperbolic tree – lamping, rao 19

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

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

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

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

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

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

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 / Space. Tree – 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 26

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

elastic hierarchies • hybrid of nodelink diagrams and treemaps elastic hierarchies - zhao, mcguffin, chignell 28

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

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!) 30

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! 31

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