Tree Structures Hierarchical Information

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Tree Structures(Hierarchical Information)

• cs5764 Information Visualization
• Chris North

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Where are we?

• Multi-D
• 1D
• 2D
• Trees
• Graphs
• 3D
• Document collections

• Design Principles
• Empirical Evaluation
• Visual Overviews

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Trees (Hierarchies)

• What is a tree?
• DAG, one parent per node
• Items structure (nodes associations)
• In table model?
• Add parent pointer attribute
• 1M

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Examples

• File system
• menus
• org charts
• Family tree
• classification/taxonomy
• Table of contents
• data structures

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Tasks

• Multi-D tasks, plus structure-based tasks
• Find descendants, ancestors, siblings, cousins
• Overall structure, height, breadth, dense/sparse
  areas

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Tree Properties

• Structure vs. attributes
• Attributes only (multi-dimensional viz)
• Structure only (1 attribute, e.g. name)
• Structure attributes
• Branching factor
• Fixed level, categorical

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Tree Visualization

• Example TreeView
• Why is tree visualization hard?
• Structure AND items
• Structure harder, consumes more space
• Data size grows very quickly (exponential)
• nodes bheight

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2 Approaches

• Connection (node link)
• outliner
• Containment (node in node)
• Venn diagram

A
C
B
A
B
C
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Connection (node link)
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TreeView

• Good for directed search tasks
• subtree filtering (/-)
• Not good for learning structure
• No attributes
• Apx 50 items visible
• Lose path to root for deep nodes
• Scroll bar!

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Mac Finder
Branching factor Small large
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Hyperbolic Trees

• Rao, Hyperbolic Tree
• http//startree.inxight.com/
• Xerox PARC
• Inxight
• Focuscontext

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Cone Trees

• Robertson, ConeTrees
• Xerox PARC
• 3D for focuscontext

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PDQ Trees

• OverviewDetail of 2D tree layout
• Dynamic Queries on each level for pruning

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PDQ Trees
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Disk Tree

• Ed Chi, Xerox PARC
• OverviewReduced visual representation

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WebTOC

• Website map TreeView size attributes
• http//www.cs.umd.edu/projects/hcil/webtoc/fhcil.h
  tml

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FSN

• SGI file system navigator
• Jurassic Park
• Zooming?

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Ugh!
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Containment (node in node)
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2 Approaches

• Connection (node link)
• Outliner
• Containment (node in node)
• Venn diagram
• Structure vs. attributes
• Attributes only (multi-dimensional viz)
• Structure only (1 attribute, e.g. name)
• Structure attributes

A
C
B
A
B
C
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Pyramids
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3D Containment
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Treemaps

• Shneiderman, Treemaps
• http//www.cs.umd.edu/hcil/treemap3/
• Maryland
• zooming

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Treemap Algorithm

• Calculate node sizes
• Recurse to children
• node size sum children sizes
• Draw Treemap (node, space, direction)
• Draw node rectangle in space
• Alternate direction (slice or dice)
• For each child
• Calculate child space as of node space using
  size and direction
• Draw Treemap (child, child space, direction)

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Squarified Treemaps

• Wattenberg
• Van Wijk

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• http//www.research.microsoft.com/masmith/all_map
  .jpg

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Cushion Treemaps

• Van Wijk
• http//www.win.tue.nl/sequoiaview/

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Dynamic Query Treemaps

• http//www.cs.umd.edu/hcil/treemap3/

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Treemaps on the Web

• Map of the Market http//www.smartmoney.com/mark
  etmap/
• People Map http//www.truepeers.com/
• Coffee Map http//www.peets.com/tast/11/coffee_s
  elector.asp

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DiskMapper

• http//www.miclog.com/dmdesc.htm

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Sunburst

• Stasko, GaTech
• Radial layout
• Animated zooming

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Sunburst (vs. Treemap)

• Faster learning time like pie chart
• Details outward, instead of inward
• Focuscontext instead of zooming
• - Not space filling
• - More space used by non-leaves
• - Less scalability?
• All leaves on 1-D space, perimeter
• Treemap 2-D space for leaves

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Misc.
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CHEOPS

• Beaudoin, Cheops
• http//www.crim.ca/hci/cheops/index1.html
• http//tecfa.unige.ch/schneide/cheops/lite1.html

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The Original Fisheye View

• George Furnas, 1981 (pg 311)
• Large information space
• User controlled focus point
• How to render items?
• Normal View just pick items nearby
• Fisheye View pick items based on degree of
  interest
• Degree of Interest function of distance from f
  and a priori importance
• DOI(x) -dist(x,f) imp(x)

f
x
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Example Tree structure

• Distance links between f and x
• Importance level of x in tree

Distance I A a i
ii b i ii
B a i ii
b i ii
Importance I A a i
ii b i ii
B a i ii
b i ii
DOI I A a i
ii b i ii B
a i ii b
i ii
f
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Challenges

• Multiple foci
• George Robertson, Microsoft Research

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Polyarchies

• multiple inter-twined trees
• Visual pivot
• George Robertson, Microsoft Research

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Nifty App of the Day

• SAS JMP

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Summary

• Hyperbolic lt1000
• TreeMap lt3000, attributes, collective
• Cheops scale up