30th International Conference on
INFORMATION TECHNOLOGY INTERFACES
Cavtat, Croatia,
June 23-26, 2008
Visualization in
science
Nataša Tepić
What is visualization?
dictionary: Visualisation is a relatively new
term which describes the process of
representing information or ideas by
diagrams or graphs.
 expansion: maps, plots, animations, video,
movies, ...

You must never tell a thing. You must
illustrate it. We learn through the eye
and not the noggin.
Will Rogers (1879 - 1935)
One picture is worth ten thousand
words.
Frederick R. Barnard: Printer's Ink
10.03.1927.
JMP
The greatest value of a picture is
when it forces us to notice what we
never expected to see.
John Tukey
History

till 16th century data visualization = maps
the oldest known map (town map)
6200 BC
Museum at Konya, Turkey
the first world map
- Anaximander from Miletus in Asia Minor (610-546 BC),
Turkey (his map has been lost, Herodotus describes it in
books “The Histories” II & IV)
History



in 15th century - Nikolaus Krebs (Nicholas of Cusa,
Nicolaus Cusanus) developed graphs of distance vs.
speed, presumably of the theoretical relation
during 16th century - development of geometric diagrams
and various maps for data exploration– official start of
data visualization
during 17th century - analytic geometry (René
Descartes, Pierre de Fermat, ...) , theories of errors of
measurement and estimation, the birth of probability
theory, and the beginnings of demographic statistics and
'' political arithmetic''
What do we see?
form
 color
 depth
 motion

Human visual system

human sight reacts more intensively on
contrast than on intensity

colors which we *see* are not completely
identical to the colors in the nature

purpose of human sight is constant object
recognition regardless of angles, distance or
lighting
Seeing is a Complex Process

Our brain constructs image from:
 information
from our eyes
 information stored in our brain
perception
process of collecting information about
world through our senses and their
interpreting
 perception depends on cultural heritage
 perception changes with experience

Do you ever get something like this
via e-mail?
Optical illusions

Illusions trick us into perceiving something
differently than it actually exists, so what
we see does not correspond to physical
reality. The word illusion comes from the
Latin verb illudere meaning, "to mock."
Why are optical illusions important
for data visualization?
inappropriate visual stimulation can
confuse our brain
 manipulative visual stimulation can cause
wrong interpretation

Optical illusions

Problems with visual perception:

area
 angles
 perspective
How much is the area of circle B?

A
B
10
??
answer: 17
angle problem
perspective problem
co-effects
Müller-Lyer
co-effects
co-effects
co-effects (pattern completion)
Johann Poggendorff’s illusion
co-effects
co-effects
co-effects
co-effects
Color Meaning
Colors are non-verbal communication. They have
symbolism and color meanings that go beyond ink.
red
blue
yellow
green
orange
purple
pink
action, confidence, courage, vitality
unity, harmony, calmness, coolness, conservatism
joy, optimism, summer, cowardice, greed
spring, fertility, youth, environment, good luck
energy, heat, enthusiasm, playfulness
royalty, nobility, ceremony, magic, mystery
femininity, love, beauty
male
female
A
B
Color Blindness
Ishihara Test for Color Blindness
About 12 - 20 percent of white males and a tiny fraction of females are color blind.
1
Top
Bottom
Normal Color Vision
Left Middle Right
25
29
45
56
6
8
Red-Green Color Blind
Left Middle Right
25
Spots
Spots
56
Spots
Spots
small squares –same color or not?
theory ....



Edward E. Tufte (professor emeritus of
statistics, graphic design, and political economy)
"The Leonardo da Vinci of data."
New York Times
he coined the term "chartjunk“.
chartjunk

This chart shows only five hard-to-read
numbers, 1, 2, 4, 8 and 16, but the digital
file of the image is 11216 bytes (numbers)
in size.
theory....
Tufte uses the term data-ink ratio and
argues strongly against the inclusion of
any non-informative decoration in visual
presentations of quantitative information
and claims that ink should only be used to
convey significant data and aid in its
interpretation.
Lurking behind chartjunk is contempt both for
information and for the audience. Chartjunk
promoters imagine that numbers and details are
boring, dull, and tedious, requiring ornament to
enliven. Cosmetic decoration, which frequently
distorts the data, will never salvage an underlying
lack of content.
If the numbers are boring, then you've got the
wrong numbers.
Credibility vanishes in clouds of chartjunk; who
would trust a chart that looks like a video game?
Edward Tufte, "Envisioning Information", 1990
If a picture is not worth a 1000 words,
to hell with it!
Ad Reinhardt
Maps
maps show variations of a variable value
with respect to an physical/geographic
area
 actual value of the response variable
corresponds to:

 height
of the object (block, polyhedron, prism,
spike,...)
 color
Maps

problems:
of the object  perspective
 color  legend
 height
Maps

benefits:
 position
 physical/geographic
information
the best statistical graphic ever
drawn

Like good writing, good graphical displays
of data communicate ideas with clarity,
precision, and efficiency.
The French engineer, Charles Minard (1781-1870), illustrated the
disastrous result of Napoleon's failed Russian campaign of 1812. The
graph shows the size of the army by the width of the band across the map
of the campaign on its outward and return legs, with temperature on the
retreat shown on the line graph at the bottom.
Many consider Minard's original the best statistical graphic ever drawn.
Why?
the best statistical graphic ever
drawn

He took a two dimensional space and managed to accurately depict five
data variables: size of invading army, size of retreating army,
geographic location, temperature, and of course, time. The multivariate
data is presented in such a way as to provide an intriguing narrative as
to the fate of Napoleon’s army.
- new version (SAS/IML)
cholera epidemic in London
1854.
Dr. John Snow (1855) observed
that cholera occurred almost
entirely among those who lived
near (and drank from) the Broad
Street water pump. He had the
handle of the contaminated
pump removed, ending the
neighborhood epidemic which
had taken more than 500 lives.
Florence Nightingale - mother of
modern nursing
After witnessing deplorable
sanitary conditions in the Crimea,
she wrote Notes on Matters
Affecting the Health, Efficiency
and Hospital Administration of the
British Army (1858), an influential
text including several graphs
which she called "Coxcombs".
This figure (reproduced with
SAS/Graph) makes it abundantly
clear that far more deaths were
attributable to non-battle causes
("preventable causes") than to
battle-related causes.
Escaping the 2D plane: The
Stereogram
By the end of the 19th century,
as more statistical data
became available, the
limitations of 2 dimensions of
the plane for the representation
of data were becoming more
apparent. Several systems for
representing 3D data were
developed between 1869-1880.
- author Luigi Perozzo
- Annali di Statistica, 1880.
- this figure shows the
population of Sweden from
1750-1875 by age groups
Chemical examples:
1.
periodic table of chemical elements
Dimitri Mendeleev (1834-1907, Russian chemist)
He predicted the chemical and physical properties of
unknown elements (e.g. Ga, Ge), and left spaces open in
his periodic table for them.
order in periodic table by mass number
Chemical examples:
2.
wavelengths of the X-ray emissions
of the elements
Henry Moseley (1887-1915, British
chemist, Rutherford’s student)
In 1913 Moseley published the results of his measurements of the
wavelengths of the X-ray spectral lines of a number of elements
which showed that the ordering of the wavelengths of the X-ray
emissions of the elements coincided with the ordering of the
elements by atomic number. It became apparent that atomic weight
was not the significant player in the periodic law as Mendeleev,
Meyers and others had proposed, but rather, the properties of the
Chemical examples:
2.
wavelengths of the X-ray emissions
of the elements
Henry Moseley (1887-1915, British
chemist, Rutherford’s student)
Moseley's graph represents an outstanding piece of numerical
and graphical detective work. He noted that there were slight
departures from linearity which he could not explain; nor could he
explain the multiple lines at the top and bottom of the figure. The
explanation came later with the discovery of the spin of the
electron.
Literature
SRCE
http://www.srce.hr/stat-sas/tecajevi.html

Gallery of Data Visualization - The Best and Worst of Statistical Graphics
http://www.math.yorku.ca/SCS/Gallery/

Milestones in the History of Thematic Cartography, Statistical Graphics, and Data Visualization
http://www.math.yorku.ca/SCS/Gallery/milestone/

Predavanja Ross Ihaka (Statistics 120 - Information Visualisation)
http://www.stat.auckland.ac.nz/~ihaka/120/

http://www.math.yorku.ca/SCS/sugi/saslogo.html
http://chemweb.calpoly.edu/ (Jennifer Retsek's Homepage)
http://www.ritsumei.ac.jp/~akitaoka/index-e.html
http://junkcharts.typepad.com/
http://www-personal.engin.umich.edu/~jpboyd/sciviz_1_graphbadly.pdf
http://CAUSEweb_org
https://www.edwardtufte.com/
http://www.csc.villanova.edu/~map/1040/Tufte1.ppt#1
http://homepages.dcc.ufmg.br/~jussara/metq/aula10.ppt#89
http://www.gautschy.ch/~alfred/SciIll/CraftingIll.html
http://spacecraft.ssl.umd.edu/old_site/academics/483F02/04_eng_graphics_2002.pdf