<s>
Scientific	B-Application
visualization	I-Application
(	O
also	O
spelled	O
scientific	B-Application
visualisation	I-Application
)	O
is	O
an	O
interdisciplinary	O
branch	O
of	O
science	O
concerned	O
with	O
the	O
visualization	B-Application
of	O
scientific	O
phenomena	O
.	O
</s>
<s>
The	O
purpose	O
of	O
scientific	B-Application
visualization	I-Application
is	O
to	O
graphically	O
illustrate	O
scientific	O
data	O
to	O
enable	O
scientists	O
to	O
understand	O
,	O
illustrate	O
,	O
and	O
glean	O
insight	O
from	O
their	O
data	O
.	O
</s>
<s>
Research	O
into	O
how	O
people	O
read	O
and	O
misread	O
various	O
types	O
of	O
visualizations	B-Application
is	O
helping	O
to	O
determine	O
what	O
types	O
and	O
features	O
of	O
visualizations	B-Application
are	O
most	O
understandable	O
and	O
effective	O
in	O
conveying	O
information	O
.	O
</s>
<s>
One	O
of	O
the	O
earliest	O
examples	O
of	O
three-dimensional	O
scientific	B-Application
visualisation	I-Application
was	O
Maxwell	O
's	O
thermodynamic	O
surface	O
,	O
sculpted	O
in	O
clay	O
in	O
1874	O
by	O
James	O
Clerk	O
Maxwell	O
.	O
</s>
<s>
This	O
prefigured	O
modern	O
scientific	B-Application
visualization	I-Application
techniques	O
that	O
use	O
computer	O
graphics	O
.	O
</s>
<s>
Notable	O
early	O
two-dimensional	O
examples	O
include	O
the	O
flow	B-Application
map	I-Application
of	O
Napoleon	O
's	O
March	O
on	O
Moscow	O
produced	O
by	O
Charles	O
Joseph	O
Minard	O
in	O
1869	O
;	O
the	O
"	O
coxcombs	O
"	O
used	O
by	O
Florence	O
Nightingale	O
in	O
1857	O
as	O
part	O
of	O
a	O
campaign	O
to	O
improve	O
sanitary	O
conditions	O
in	O
the	O
British	O
army	O
;	O
and	O
the	O
dot	O
map	O
used	O
by	O
John	O
Snow	O
in	O
1855	O
to	O
visualise	O
the	O
Broad	O
Street	O
cholera	O
outbreak	O
.	O
</s>
<s>
Scientific	B-Application
visualization	I-Application
using	O
computer	O
graphics	O
gained	O
in	O
popularity	O
as	O
graphics	O
matured	O
.	O
</s>
<s>
Primary	O
applications	O
were	O
scalar	O
fields	O
and	O
vector	O
fields	O
from	O
computer	B-Application
simulations	I-Application
and	O
also	O
measured	O
data	O
.	O
</s>
<s>
2D	O
vector	O
fields	O
are	O
visualized	O
using	O
glyphs	B-Application
and	O
streamlines	B-Application
or	O
line	O
integral	O
convolution	O
methods	O
.	O
</s>
<s>
2D	O
tensor	O
fields	O
are	O
often	O
resolved	O
to	O
a	O
vector	O
field	O
by	O
using	O
one	O
of	O
the	O
two	O
eigenvectors	O
to	O
represent	O
the	O
tensor	O
each	O
point	O
in	O
the	O
field	O
and	O
then	O
visualized	O
using	O
vector	O
field	O
visualization	B-Application
methods	O
.	O
</s>
<s>
Methods	O
for	O
visualizing	O
vector	O
fields	O
include	O
glyphs	B-Application
(	O
graphical	O
icons	O
)	O
such	O
as	O
arrows	O
,	O
streamlines	B-Application
and	I-Application
streaklines	I-Application
,	O
particle	O
tracing	O
,	O
line	O
integral	O
convolution	O
(	O
LIC	O
)	O
and	O
topological	O
methods	O
.	O
</s>
<s>
Later	O
,	O
visualization	B-Application
techniques	O
such	O
as	O
hyperstreamlines	O
were	O
developed	O
to	O
visualize	O
2D	O
and	O
3D	O
tensor	O
fields	O
.	O
</s>
<s>
It	O
is	O
becoming	O
more	O
common	O
to	O
be	O
created	O
by	O
means	O
of	O
3D	O
computer	O
graphics	O
,	O
though	O
2D	O
computer	O
graphics	O
are	O
still	O
widely	O
used	O
for	O
stylistic	O
,	O
low	O
bandwidth	O
,	O
and	O
faster	O
real-time	B-General_Concept
rendering	I-General_Concept
needs	O
.	O
</s>
<s>
Computer	B-Application
simulation	I-Application
is	O
a	O
computer	O
program	O
,	O
or	O
network	O
of	O
computers	O
,	O
that	O
attempts	O
to	O
simulate	O
an	O
abstract	O
model	O
of	O
a	O
particular	O
system	O
.	O
</s>
<s>
Computer	B-Application
simulations	I-Application
have	O
become	O
a	O
useful	O
part	O
of	O
mathematical	O
modelling	O
of	O
many	O
natural	O
systems	O
in	O
physics	O
,	O
and	O
computational	O
physics	O
,	O
chemistry	O
and	O
biology	O
;	O
human	O
systems	O
in	O
economics	O
,	O
psychology	O
,	O
and	O
social	O
science	O
;	O
and	O
in	O
the	O
process	O
of	O
engineering	O
and	O
new	O
technology	O
,	O
to	O
gain	O
insight	O
into	O
the	O
operation	O
of	O
those	O
systems	O
,	O
or	O
to	O
observe	O
their	O
behavior	O
.	O
</s>
<s>
The	O
simultaneous	O
visualization	B-Application
and	O
simulation	O
of	O
a	O
system	O
is	O
called	O
visulation	O
.	O
</s>
<s>
Computer	B-Application
simulations	I-Application
vary	O
from	O
computer	O
programs	O
that	O
run	O
a	O
few	O
minutes	O
,	O
to	O
network-based	O
groups	O
of	O
computers	O
running	O
for	O
hours	O
,	O
to	O
ongoing	O
simulations	O
that	O
run	O
for	O
months	O
.	O
</s>
<s>
The	O
scale	O
of	O
events	O
being	O
simulated	O
by	O
computer	B-Application
simulations	I-Application
has	O
far	O
exceeded	O
anything	O
possible	O
(	O
or	O
perhaps	O
even	O
imaginable	O
)	O
using	O
the	O
traditional	O
paper-and-pencil	O
mathematical	O
modeling	O
:	O
over	O
10	O
years	O
ago	O
,	O
a	O
desert-battle	O
simulation	O
,	O
of	O
one	O
force	O
invading	O
another	O
,	O
involved	O
the	O
modeling	O
of	O
66,239	O
tanks	O
,	O
trucks	O
and	O
other	O
vehicles	O
on	O
simulated	O
terrain	O
around	O
Kuwait	O
,	O
using	O
multiple	O
supercomputers	O
in	O
the	O
DoD	O
High	B-General_Concept
Performance	I-General_Concept
Computing	I-General_Concept
Modernization	I-General_Concept
Program	I-General_Concept
.	O
</s>
<s>
Information	B-Application
visualization	I-Application
is	O
the	O
study	O
of	O
"	O
the	O
visual	B-Application
representation	I-Application
of	O
large-scale	O
collections	O
of	O
non-numerical	O
information	O
,	O
such	O
as	O
files	O
and	O
lines	O
of	O
code	O
in	O
software	O
systems	O
,	O
library	O
and	O
bibliographic	O
databases	O
,	O
networks	O
of	O
relations	O
on	O
the	O
internet	O
,	O
and	O
so	O
forth	O
"	O
.	O
</s>
<s>
Information	B-Application
visualization	I-Application
focused	O
on	O
the	O
creation	O
of	O
approaches	O
for	O
conveying	O
abstract	O
information	O
in	O
intuitive	O
ways	O
.	O
</s>
<s>
Visual	B-Application
representations	I-Application
and	O
interaction	O
techniques	O
take	O
advantage	O
of	O
the	O
human	O
eye	O
's	O
broad	O
bandwidth	O
pathway	O
into	O
the	O
mind	O
to	O
allow	O
users	O
to	O
see	O
,	O
explore	O
,	O
and	O
understand	O
large	O
amounts	O
of	O
information	O
at	O
once	O
.	O
</s>
<s>
The	O
key	O
difference	O
between	O
scientific	B-Application
visualization	I-Application
and	O
information	B-Application
visualization	I-Application
is	O
that	O
information	B-Application
visualization	I-Application
is	O
often	O
applied	O
to	O
data	O
that	O
is	O
not	O
generated	O
by	O
scientific	O
inquiry	O
.	O
</s>
<s>
Interface	O
technology	O
and	O
perception	O
shows	O
how	O
new	O
interfaces	O
and	O
a	O
better	O
understanding	O
of	O
underlying	O
perceptual	O
issues	O
create	O
new	O
opportunities	O
for	O
the	O
scientific	B-Application
visualization	I-Application
community	O
.	O
</s>
<s>
It	O
would	O
contain	O
geometry	O
,	O
viewpoint	O
,	O
texture	O
,	O
lighting	O
,	O
and	O
shading	B-General_Concept
information	O
.	O
</s>
<s>
The	O
image	O
is	O
a	O
digital	B-Algorithm
image	I-Algorithm
or	O
raster	B-Algorithm
graphics	I-Algorithm
image	O
.	O
</s>
<s>
A	O
high-level	O
representation	O
of	O
an	O
image	O
necessarily	O
contains	O
elements	O
in	O
a	O
different	O
domain	O
from	O
pixels	B-Algorithm
.	O
</s>
<s>
Ray	B-Algorithm
casting	I-Algorithm
is	O
primarily	O
used	O
for	O
realtime	O
simulations	O
,	O
such	O
as	O
those	O
used	O
in	O
3D	O
computer	O
games	O
and	O
cartoon	O
animations	O
,	O
where	O
detail	O
is	O
not	O
important	O
,	O
or	O
where	O
it	O
is	O
more	O
efficient	O
to	O
manually	O
fake	O
the	O
details	O
in	O
order	O
to	O
obtain	O
better	O
performance	O
in	O
the	O
computational	O
stage	O
.	O
</s>
<s>
This	O
produces	O
more	O
realistic	O
shading	B-General_Concept
and	O
seems	O
to	O
better	O
capture	O
the	O
'	O
ambience	O
 '	O
of	O
an	O
indoor	O
scene	O
.	O
</s>
<s>
Ray	B-Algorithm
tracing	I-Algorithm
is	O
an	O
extension	O
of	O
the	O
same	O
technique	O
developed	O
in	O
scanline	B-Algorithm
rendering	I-Algorithm
and	O
ray	B-Algorithm
casting	I-Algorithm
.	O
</s>
<s>
Unlike	O
scanline	O
and	O
casting	O
,	O
ray	B-Algorithm
tracing	I-Algorithm
is	O
almost	O
always	O
a	O
Monte	O
Carlo	O
technique	O
,	O
that	O
is	O
one	O
based	O
on	O
averaging	O
a	O
number	O
of	O
randomly	O
generated	O
samples	O
from	O
a	O
model	O
.	O
</s>
<s>
Volume	O
rendering	O
is	O
a	O
technique	O
used	O
to	O
display	O
a	O
2D	O
projection	O
of	O
a	O
3D	O
discretely	O
sampled	B-Algorithm
data	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
A	O
typical	O
3D	O
data	B-General_Concept
set	I-General_Concept
is	O
a	O
group	O
of	O
2D	O
slice	O
images	O
acquired	O
by	O
a	O
CT	O
or	O
MRI	O
scanner	O
.	O
</s>
<s>
Usually	O
these	O
are	O
acquired	O
in	O
a	O
regular	O
pattern	O
(	O
e.g.	O
,	O
one	O
slice	O
every	O
millimeter	O
)	O
and	O
usually	O
have	O
a	O
regular	O
number	O
of	O
image	O
pixels	B-Algorithm
in	O
a	O
regular	O
pattern	O
.	O
</s>
<s>
This	O
is	O
an	O
example	O
of	O
a	O
regular	O
volumetric	O
grid	O
,	O
with	O
each	O
volume	O
element	O
,	O
or	O
voxel	B-Algorithm
represented	O
by	O
a	O
single	O
value	O
that	O
is	O
obtained	O
by	O
sampling	O
the	O
immediate	O
area	O
surrounding	O
the	O
voxel	B-Algorithm
.	O
</s>
<s>
According	O
to	O
Rosenblum	O
(	O
1994	O
)	O
"	O
volume	O
visualization	B-Application
examines	O
a	O
set	O
of	O
techniques	O
that	O
allows	O
viewing	O
an	O
object	O
without	O
mathematically	O
representing	O
the	O
other	O
surface	O
.	O
</s>
<s>
Initially	O
used	O
in	O
medical	B-Application
imaging	I-Application
,	O
volume	O
visualization	B-Application
has	O
become	O
an	O
essential	O
technique	O
for	O
many	O
sciences	O
,	O
portraying	O
phenomena	O
become	O
an	O
essential	O
technique	O
such	O
as	O
clouds	O
,	O
water	O
flows	O
,	O
and	O
molecular	O
and	O
biological	O
structure	O
.	O
</s>
<s>
Many	O
volume	O
visualization	B-Application
algorithms	O
are	O
computationally	O
expensive	O
and	O
demand	O
large	O
data	O
storage	O
.	O
</s>
<s>
Advances	O
in	O
hardware	O
and	O
software	O
are	O
generalizing	O
volume	O
visualization	B-Application
as	O
well	O
as	O
real	O
time	O
performances	O
"	O
.	O
</s>
<s>
This	O
section	O
will	O
give	O
a	O
series	O
of	O
examples	O
how	O
scientific	B-Application
visualization	I-Application
can	O
be	O
applied	O
today	O
.	O
</s>
<s>
Molecular	O
rendering	O
:	O
VisIt	O
's	O
general	O
plotting	O
capabilities	O
were	O
used	O
to	O
create	O
the	O
molecular	O
rendering	O
shown	O
in	O
the	O
featured	O
visualization	B-Application
.	O
</s>
<s>
The	O
original	O
data	O
was	O
taken	O
from	O
the	O
Protein	O
Data	O
Bank	O
and	O
turned	O
into	O
a	O
VTK	B-Language
file	O
before	O
rendering	O
.	O
</s>
<s>
Terrain	O
visualization	B-Application
:	O
VisIt	O
can	O
read	O
several	O
file	O
formats	O
common	O
in	O
the	O
field	O
of	O
Geographic	B-Application
Information	I-Application
Systems	I-Application
(	O
GIS	B-Application
)	O
,	O
allowing	O
one	O
to	O
plot	O
raster	O
data	O
such	O
as	O
terrain	O
data	O
in	O
visualizations	B-Application
.	O
</s>
<s>
The	O
featured	O
image	O
shows	O
a	O
plot	O
of	O
a	O
DEM	O
dataset	B-General_Concept
containing	O
mountainous	O
areas	O
near	O
Dunsmuir	O
,	O
CA	O
.	O
</s>
<s>
The	O
tornado	O
is	O
shown	O
by	O
spheres	O
that	O
are	O
colored	O
according	O
to	O
pressure	O
;	O
orange	B-Application
and	O
blue	O
tubes	O
represent	O
the	O
rising	O
and	O
falling	O
airflow	O
around	O
the	O
tornado	O
.	O
</s>
<s>
Climate	O
visualization	B-Application
:	O
This	O
visualization	B-Application
depicts	O
the	O
carbon	O
dioxide	O
from	O
various	O
sources	O
that	O
are	O
advected	O
individually	O
as	O
tracers	O
in	O
the	O
atmosphere	O
model	O
.	O
</s>
<s>
Scientific	B-Application
visualization	I-Application
of	O
mathematical	O
structures	O
has	O
been	O
undertaken	O
for	O
purposes	O
of	O
building	O
intuition	O
and	O
for	O
aiding	O
the	O
forming	O
of	O
mental	O
models	O
.	O
</s>
<s>
In	O
complex	O
analysis	O
,	O
functions	O
of	O
the	O
complex	O
plane	O
are	O
inherently	O
4-dimensional	O
,	O
but	O
there	O
is	O
no	O
natural	O
geometric	O
projection	O
into	O
lower	O
dimensional	O
visual	B-Application
representations	I-Application
.	O
</s>
<s>
Instead	O
,	O
colour	O
vision	O
is	O
exploited	O
to	O
capture	O
dimensional	O
information	O
using	O
techniques	O
such	O
as	O
domain	B-Application
coloring	I-Application
.	O
</s>
<s>
The	O
imaging	O
is	O
part	O
of	O
the	O
work	O
on	O
the	O
NSF-funded	O
Electronic	O
Visualization	B-Application
Laboratory	O
at	O
the	O
University	O
of	O
Illinois	O
at	O
Chicago	O
.	O
</s>
<s>
Curve	O
plots	O
:	O
VisIt	O
can	O
plot	O
curves	O
from	O
data	O
read	O
from	O
files	O
and	O
it	O
can	O
be	O
used	O
to	O
extract	O
and	O
plot	O
curve	O
data	O
from	O
higher-dimensional	O
datasets	B-General_Concept
using	O
lineout	O
operators	O
or	O
queries	O
.	O
</s>
<s>
Image	O
annotations	O
:	O
The	O
featured	O
plot	O
shows	O
Leaf	O
Area	O
Index	O
(	O
LAI	O
)	O
,	O
a	O
measure	O
of	O
global	O
vegetative	O
matter	O
,	O
from	O
a	O
NetCDF	O
dataset	B-General_Concept
.	O
</s>
<s>
Image	O
annotations	O
can	O
be	O
used	O
to	O
include	O
material	O
that	O
enhances	O
a	O
visualization	B-Application
such	O
as	O
auxiliary	O
plots	O
,	O
images	O
of	O
experimental	O
data	O
,	O
project	O
logos	O
,	O
etc	O
.	O
</s>
<s>
The	O
different	O
variables	O
are	O
combined	O
to	O
form	O
coordinates	O
in	O
the	O
phase	O
space	O
and	O
they	O
are	O
displayed	O
using	O
glyphs	B-Application
and	O
colored	O
using	O
another	O
scalar	O
variable	O
.	O
</s>
<s>
VisIt	O
can	O
read	O
a	O
limited	O
subset	O
of	O
NASTRAN	O
bulk	O
data	O
files	O
,	O
in	O
general	O
enough	O
to	O
import	O
model	O
geometry	O
for	O
visualization	B-Application
.	O
</s>
<s>
YF-17	O
aircraft	O
Plot	O
:	O
The	O
featured	O
image	O
displays	O
plots	O
of	O
a	O
CGNS	O
dataset	B-General_Concept
representing	O
a	O
YF-17	O
jet	O
aircraft	O
.	O
</s>
<s>
The	O
dataset	B-General_Concept
consists	O
of	O
an	O
unstructured	O
grid	O
with	O
solution	O
.	O
</s>
<s>
The	O
image	O
was	O
created	O
by	O
using	O
a	O
pseudocolor	O
plot	O
of	O
the	O
dataset	B-General_Concept
's	O
Mach	O
variable	O
,	O
a	O
Mesh	O
plot	O
of	O
the	O
grid	O
,	O
and	O
Vector	O
plot	O
of	O
a	O
slice	O
through	O
the	O
Velocity	O
field	O
.	O
</s>
<s>
Inbound	O
traffic	O
measured	O
:	O
This	O
image	O
is	O
a	O
visualization	B-Application
study	O
of	O
inbound	O
traffic	O
measured	O
in	O
billions	O
of	O
bytes	O
on	O
the	O
NSFNET	O
T1	O
backbone	O
for	O
the	O
month	O
of	O
September	O
1991	O
.	O
</s>
<s>
Conferences	O
in	O
this	O
field	O
,	O
ranked	O
by	O
significance	O
in	O
scientific	B-Application
visualization	I-Application
research	O
,	O
are	O
:	O
</s>
