Trees Hierarchical Information

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Trees(Hierarchical Information)

• cs5984 Information Visualization
• Chris North

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Where are we?

• Multi-D
• 1D
• 2D
• Hierarchies/Trees
• Networks/Graphs
• Document collections
• 3D

• Design Principles
• Empirical Evaluation
• Java Development
• Visual Overviews
• Multiple Views

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Quiz

• 2 strategies for making overviews
• hammer
• chainsaw
• 3 strategies for linking multiple views
• synch nav
• Brushing
• OD

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Trees (Hierarchies)

• What is a tree?
• DAG, one parent per node
• Items structure (nodes links)
• Table model Add parent pointer attribute
• Examples
• filesystem, family, classification/taxonomy, org
  charts, toc, data structures, menus
• Tasks
• All previous tasks plus structure-based tasks
• Find descendants, ancestors, siblings, cousins
• Overall structure, height, breadth, dense/sparse
  areas

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Tree Visualization

• Example Outliner
• 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

today
A
C
B
A
B
C
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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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Outliner

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

• cant see all the tree structure
• Scroll bar suck
• Structure only
• Lost screen space
• 50 nodes
• Filtering open/close
• Search tasks ok
• Browsing not good
• Icons?

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Mac Finder
Branching factor Small large
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Hyperbolic Trees

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

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Disk Tree

• Ed Chi, Xerox PARC

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Cone Trees

• Robertson, ConeTrees
• Anuj, Atul
• Xerox PARC

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FSN

• SGI file system navigator
• Jurassic Park

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Ugh!
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WebTOC

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

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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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Nifty App of the Day

• SAS JMP

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Hard Problems

• Multiple foci
• Robertson, Microsoft Research
• Polyarchies multiple inter-twined trees

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Assignment

• Thurs Trees
• Johnson, Treemaps
• vishal, jeevak
• Beaudoin, Cheops
• jon, mudita
• Tues Oct 30 Project status report due
• Thurs Nov 1 Homework 3 due
• Purvi HiNote info session, Fri 4pm, McB 104c
• Note I will be away next week

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Next Week

• Book chapter 6
• Tues Dr. McCrickard
• Healey, Preattentive Processing
• parool, priya
• Somervell, InfoVis in the Periphery
• ali, vikrant
• Thurs Virtual Environments
• Go directly to Torg 3050
• Dr. Bowman, Alex Kalita