Transcript Visualizing Hierarchies

Information Visualization 2
Case Study: Portraying Hierarchies
• Visualizing hierarchies
 Variety of techniques
Traditional tree views, alternatives, space-filling views
Hierarchies
• Definition
 Ordering of items in which particular items are
parents or ancestors of others
• Example: File System
 Folders/Directories with folders/subdirectories and
files inside
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Trees
• Hierarchies often represented as trees
• Root at top, leaves at bottom
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Sample Representation
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Another Representation
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Another Representation
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Another Representation
root
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Another Representation
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Potential Problems
• Width of fan-out uses real estate
 Run out of room quickly
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Another Idea
CHEOPS
Beaudoin, Parent & Vroomen
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Another Idea
ConeTree
Card, Mackinlay & Robertson
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Another Idea
• Use hyperbolic geometry
• Hyperbolic tree
• Here: Site Lens from
www.inxight.com
• Demo
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Lamping & Rao
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Space-Filling Representation
Each item occupies an area
Children are “contained” under parent
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Treemap
• Space-filling representation developed by
Shneiderman and Johnson
• Children are drawn inside their parent
• Alternate horizontal and vertical slicing at
each successive level
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Treemap
• Example
File and
directory
visualizer
level 1
dirs
white-directories
color-files
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Treemap
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Nested vs. Non-nested
Treemaps
Nested Tree-Map
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Non-nested Tree-Map
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Treemap Affordances
• Good representation of two attributes:
color and area
• Not as good at representing structure
 What happens if it’s a perfectly balanced tree
of items all the same size?
 Also can get long-thin aspect ratios
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Treemap Variation
• SmartMoney.com Map of the Market
 Illustrates stock movements
 “Compromises” treemap
algorithm to avoid bad
aspect ratios
www.smartmoney.com/marketmap
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Treemap Variation
Demo
• Use 3D
shading
cues to
help
convey
structure
SequoiaView
file viewer for
Windows
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Another Technique
• What if we used a radial rather than a
rectangular space-filling technique?
Sunburst
• Demonstration of system
/usr/local/bin/sunburst
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Sunburst
Visualizing file
and directory
structures
Root dir at center
Color - file type
Angle - file/dir size
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Experiment
• Compare Treemap and Sunburst with
users performing typical file/directoryrelated tasks
• Evaluate task performance on both
correctness and time
Small Hierarchy
(~500 files)
A
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Large Hierarchy
(~3000 files)
A
B
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Experiment
• 60 participants
• Participant only works with a small or
large hierarchy in a session
• Vary order across participants
SB A, TM B
TM A, SB B
SB B, TM A
TM B, SB A
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32 on small hierarchies
28 on large hierarchies
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Tasks
• Identification (naming or pointing out) of a file based on size,
specifically, the largest and second largest files (Questions 1-2)
• Identification of a directory based on size, specifically, the largest (Q3)
• Location (pointing out) of a file, given the entire path and name (Q4-7)
• Location of a file, given only the file name (Q8-9)
• Identification of the deepest subdirectory (Q10)
• Identification of a directory containing files of a particular type (Q11)
• Identification of a file based on type and size, specifically, the largest
file of a particular type (Q12)
• Comparison of two files by size (Q13)
• Location of two duplicated directory structures (Q14)
• Comparison of two directories by size (Q15)
• Comparison of two directories by number of files contained (Q16)
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Results
• Ordering effect for Treemap on large
hierarchies
• Performance trends favored Sunburst, but
not clear-cut
• Subjective preference:
SB (51), TM (9), unsure (1)
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Observations
• SB appeared to convey structure better
• Participants felt TM conveyed size better,
but not bore out
• Strategies mattered
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SunBurst Negative
• In large hierarchies, files at the periphery
are usually
examples
tiny and very
difficult to
distinguish
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Fix: Objectives
• Make small slices bigger
• Maintain full circular
space-filling idea
• Allow detailed
examination of small files
within context of entire
hierarchy
• Don’t alter ratios of sizes
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• Avoid use of multiple
windows or lots of
scrollbars
• Provide an
aesthetically pleasing
interface in which it is
easy to track changes
in focus
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3 Solutions
• Three visualization+navigation techniques
developed to help remedy the
shortcoming
 Angular detail
 Detail outside
 Detail inside
With Eugene Zhang
Proceedings of Information Visualization 2000,
Oct. 2000, pp. 57-65.
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Angular Detail
• Most “natural”
• Least space-efficient
• Most configurable by
user
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Detail Outside
• Exhibits non-distorted
miniature of overview
• Somewhat visually
disconcerting
• Focus is quite enlarged
(large circumference
and 360°)
• Relatively space
efficient
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Detail Inside
• Perhaps least intuitive
and most distorting
• Items in overview are
more distinct (larger
circumference)
• Interior 360° for focus
is often sufficient
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Video
4 minutes
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Key Components
• Two ways to increase area for focus
region: larger sweep angle and longer
circumference
• Smooth transitions between overview and
focus allow viewer to track changes
• Always display overview
• Allow focus selections from anywhere:
normal display, focus or overview regions
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