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Information Visualization

What and when to use it

Examples

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Information Age

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Some Definitions

• What exactly is visualization?

– Is it something a computer does?

– Is it something humans do?

– Or is it something humans do with computers?

• The idea of visualization is a bit fuzzy

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What is Visualization?

• Two possible definitions:

visualize: (vb) to form a mental image or vision of�

visualize: (vb) to imagine or remember as if actually seeing�

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What is Visualization?

• Two possible definitions:

– Visualization is a cognitive activity that humans engage in

– Visualization goes on in the mind and is thus an internal

representation which is difficult to study

visualize: (vb) to form a mental image of vision of�

visualize: (vb) to imagine or remember as if actually seeing�

visualize: (vb) to form a mental image of vision of�

visualize: (vb) to imagine or remember as if actually seeing�

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What is Visualization?

• So far no mention of the use of computers

• In fact, computers are modern tools that can be used to facilitate the visualization process

• Thus define information visualization as the use of computer-supported, interactive, visual representations of data to amplify cognition

• In other words, information visualization uses computational tools to help us to think about data in different ways

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An Example

• In many situations, data is available in large quantities, and some human insight is required

• An example of such a

situation is traveling via the bus: we have to understand how to get from A to B

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An Example

• Suppose we want to travel from A to B. We focus our attention on departure and destination stations and the route between them

• We do not memorize the entire map. Rather we visualize the relevant portion(s) of the real map internally (i.e. ‘take 62 on the blue line then 78 on the green line’)

• This internal model of the real map is referred to as a cognitive map, which is available to mental inspection as the real map is to real inspection

• Thus, the printed version of the bus schedule is a visualizationtool that allows us to easily form an appropriate cognitive map

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Iran 3 yrs

India 3 yrs

Niamey, Niger 9 yrs

F’ton, NB 11 yrs

Ottawa, ON 1 yr

Rabat, Morocco 1 yr

Wpg, MB 5 yrs

Professor’s travels

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Some Classic Examples

• The idea of using graphical abstractions to represent data in different ways seems almost intuitive today

• However, this notion is a relatively recent event historically speaking

• A well known pioneer in this area is William Playfair(1759-1823) who sought to replace tables of numbers with systematic visual representations

• The result of his work were some simple and powerful ways to describe, explore and summarize sets of numbers

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Playfair’s Circles

area of

country

population

taxes

collected

Graphic from E.R. Tufte, The Visual Display of Quantitative Information, 1983

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Playfair’s Circles

sign of slope:

is the country

burdened with taxes?

Britain suffers

from excessive taxation

Issues

Does the slope ‘catch our

attention’? How can we

encode more information

here? Color?

Issues

Does the slope ‘catch our

attention’? How can we

encode more information

here? Color?11/30/2008 Comp 3020 - HCI 1 (PPI) 14

The Terrible Fate of Napoleon’s Army in Russia (C. J. Minard)

Graphic from E.R. Tufte, The Visual Display of Quantitative Information, 1983

11/30/2008 Comp 3020 - HCI 1 (PPI) 15Graphic from E.R. Tufte, The Visual Display of Quantitative Information, 1983

A good example of increasing density of data using a graphical tool.

Six variables are plotted in this two dimensional graphic!

1. time 2. temperature/day 3. longitude

4. latitude 5. army size/day 6. army position/day (color indicates

direction of travel)

time

Lat

Long

size/day

temp.

position/day

temp/day

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The Terrible Fate of Napoleon’s Army in Russia (C. J. Minard)

Graphic from E.R. Tufte, The Visual Display of Quantitative Information, 1983

Issues

Faced with huge data sets, how does one strike a

balance between simplicity and complexity?

Can additional information be included in the

graphics?

Are there any areas where more information is

beneficial?

How can we develop computational tools that

address these issues?

Issues

Faced with huge data sets, how does one strike a

balance between simplicity and complexity?

Can additional information be included in the

graphics?

Are there any areas where more information is

beneficial?

How can we develop computational tools that

address these issues?

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Dr. John Snow’s use of

graphical tool to locate

source of cholera

outbreak (Soho, 1845)

cholera victim

water pump

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Dr. John Snow’s use of

graphical tool to locate

source of cholera

outbreak (Soho, 1845)

cholera victim

water pump

contaminated water source

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Dr. John Snow’s use of

graphical tool to locate

source of cholera

outbreak (Soho, 1845)

cholera victim

water pump

Issues

Could the link between the Broad Street

pump and the cholera epidemic have been

found without the use of graphics?

How could modern interactive computer

graphics have helped Dr. Snow isolate the

source of the outbreak?

Issues

Could the link between the Broad Street

pump and the cholera epidemic have been

found without the use of graphics?

How could modern interactive computer

graphics have helped Dr. Snow isolate the

source of the outbreak?

11/30/2008 Comp 3020 - HCI 1 (PPI) 20Source: Simon Clark http://www.simonclarke.org/lul/maps/lul.gif

The tale of The tale of The tale of The tale of ‘‘‘‘The TubeThe TubeThe TubeThe Tube’’’’

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11/30/2008 Comp 3020 - HCI 1 (PPI) 21Source: R. Gardiner http://www.nyclondon.com/blog/images/tube_geo.jpg

Tube map superimposed over London

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Is There a Simpler Way?

• The map of the Tube is accurate yet very complex

• How can graphical techniques help?

• Harry Beck (1931) realized ‘when you’re underground it really doesn’t matter where you are!’

• As long as the stations are presented in sequence and interchanges are clearly delineated, scale can be distorted

• The result … a truly brilliant idea!

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Lines are drawn horizontally, vertically or at

45 degree angles.

Scale is distorted but sequences of stations

and information about location of

interchanges is preserved.

The map aids cognition by eliminating the

unnecessary spatial elements

The idea has been put to use worldwide

Lines are drawn horizontally, vertically or at

45 degree angles.

Scale is distorted but sequences of stations

and information about location of

interchanges is preserved.

The map aids cognition by eliminating the

unnecessary spatial elements

The idea has been put to use worldwide11/30/2008 Comp 3020 - HCI 1 (PPI) 24

Visualizing Linear Structures

SeeSoft view of fifty-two files containing 15, 255 lines of code

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Cone Trees

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Hyperbolic Browser

• Use hyperbolic geometry

• Hyperbolic tree

• Here: Site Lens fromwww.inxight.com

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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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Visualizing Networks

SeeNet: Call connections on the AT&T network on December 24th

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Visualizing Networks

NV3D: 6 Millions line of code

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Visualizing Entity-Relationships

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Visualizing Entity-Relationships

The Geon Diagram

[Irani & Ware, 2002]

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Illusionary Effects

Be aware of illusions

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What did we cover

• Good visual design can lead to insight

• Visualization should amplify cognition, but also targeted at tasks

• Need empirical support to determine which representations are best for a given task