Information Visualization

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Information Visualization

• Based on a lecture by John Stasko
• April 18, 2003 in CS 4750

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Agenda

• Questions?
• Announcements
• More Ubicomp videos
• Information Visualization mini-lecture

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Announcments

• Wednesday, Friday be here, and be ON TIME!
• If you havent received feedback from me on your
  evaluation plan revisions, send them to Ed
• Project presentations are the 19th, 21st, and
  23rd. Email Ed with your order of preference
• Writeups are due the 19th see Ed before the 17th
  for feedback

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More ubicomp movies
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Data Explosion

• Incredible amount of data available
• News, Weather, Traffic, Sports scores, Articles,
  Pictures, Financial information, E-mails,
• Greatly facilitated byInternet and Web

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How much data?

• Estimates of between 1 and 2 exabytes of unique
  data produced per year
• 1000000000000000000 (1018) bytes
• 250 meg for every man, woman and child
• Printed documents only .003 of total

Peter Lyman and Hal Varian, 2000 Cal-Berkeley,
Info Mgmt Systems www.sims.berkeley.edu/how-much
-info
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Big Challenge

• How do we make sense of it?
• How do we harness this data in decision-making
  processes?

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Three Possible Approaches

• Software Agents
• Computational agent that carries out users
  request
• Data Mining
• Software that analyzes database and extracts
  interesting features
• Information Visualization
• Visual tools to help users better examine the
  data themselves

Can be complementary
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Knowledge Acquisition
Web,Books,Papers, Game scores, Scientific
data, Biotech, Shopping People Stock/finance News

Data
Data Transfer
How?
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Human Vision

• Highest bandwidth sense
• Fast, parallel
• Pattern recognition
• Pre-attentive
• Extends memory and cognitive capacity
• (Multiplication test)
• People think visually
• Impressive. Lets use it!

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Example
Which state has the highest income? Is there a
relationship between income and education? Are
there any outliers?
Questions
Example courtesyof Chris North
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Visualize the Data
College Degree
Per Capita Income
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Even Tougher?

• What if you could only see 1 states data at a
  time? (e.g. Census Bureaus website)
• What if I read the data to you?

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Illustrates the Idea

• Provide tools that present data in a way to help
  people understand and gain insight from it
• Cliches
• Seeing is believing
• A picture is worth a thousand words

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Visualization

• Often thought of as process of making a graphic
  or an image
• Really is a cognitive process
• Form a mental image of something
• Internalize an understanding
• The purpose of visualization is insight, not
  pictures
• Insight discovery, decision making, explanation

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Main Idea

• Visuals help us think
• Provide a frame of reference, a temporary storage
  area
• External cognition
• Role of external world in thinking and reason

More examples
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Atlanta Flight Traffic
AJC
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Napoleans March
From E. Tufte The Visual Display of Quantitative
Information
size of army direction
latitude longitude
temperature date
Minard graphic
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London Subway
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True Geography
www.kottke.org/plus/misc/images/tubegeo.gif
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Information Visualization

• What is information?
• Items, entities, things which do not have a
  direct physical correspondence
• Notion of abstractness of the entities is
  important too
• Examples baseball statistics, stock trends,
  connections between criminals, car attributes...

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Information Visualization

• What is visualization?
• The use of computer-supported, interactive visual
  representations of data to amplify cognition.
• From Card, Mackinlay Shneiderman 98

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Information Visualization

• Essence
• Taking items without a physical correspondence
  and mapping them to a 2-D or 3-D physical space.
• Giving information a visual representation that
  is useful for analysis and decision-making

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Two Key Attributes

• Scale
• Challenge often arises when data sets become very
  large
• Interactivity
• Want to show multiple different perspectives on
  the data

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Domains for Info Vis

• Text
• Statistics
• Financial/business data
• Internet information
• Software
• ...

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Components of Study

• Data analysis
• Data items with attributes or variables
• Generate data tables
• Visual structures
• Spatial substrate, marks, graphical properties of
  marks
• UI and interaction
• Analytic tasks to be performed
• Browse, correlate, identify, associate

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More Examples

• Seeing is believing

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NYC Weather
Tufte, Vol. 1
2220 numbers
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HomeFinder
HCIL Univ. Maryland
Demo
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Case Study

• Understanding hierarchies
• Learn about some InfoVis techniques

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Hierarchies

• Definition
• Data repository in which cases are related to
  subcases
• Can be thought of as imposing an ordering in
  which cases are parents or ancestors of other
  cases

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Hierarchies in the World

• Pervasive
• Family histories, ancestries
• File/directory systems on computers
• Organization charts
• Animal kingdom Phylum,, genus,
• Object-oriented software classes
• ...
• Hierarchies often represented as trees

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Representations
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Space-Filling Representation
Each item occupies an area Children are
contained under parent
One example
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Treemap

• Space-filling representation developed by
  Shneiderman and Johnson, Vis 91
• Children are drawn inside their parent
• Alternate horizontal and vertical slicing at each
  successive level
• Use area to encode other variable of data items

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Treemap

• Example

Directories
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Map of the Market
www.smartmoney.com/marketmap
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Sunburst
Visualizing fileand directory structures Root
dir at center Color - file type Angle - file/dir
size
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InfoVis Techniques

• Aggregation
• Accumulate individual elements into a larger unit
  to be presented as some whole
• Overview Detail
• Provide both global overview and detail zooming
  capabilities
• Focus Context
• Show details of one or more regions in a more
  global context (eg, fisheye)

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InfoVis Techniques

• Drill-down
• Select individual item or smaller set of items
  from a display for a more detailed view/analysis
• Brushing
• Select or designate/specify value, then see
  pertinent items elsewhere on the display

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Upcoming

• In-class evaluations
• CSCW DFAB 13.2, 14