<s>
VisIt	O
is	O
an	O
open-source	B-Application
interactive	O
parallel	B-Operating_System
visualization	B-Application
and	O
graphical	O
analysis	O
tool	O
for	O
viewing	O
scientific	O
data	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
to	O
visualize	O
scalar	O
and	O
vector	O
fields	O
defined	O
on	O
2D	B-Algorithm
and	O
3D	O
structured	O
and	O
unstructured	B-Algorithm
meshes	O
.	O
</s>
<s>
VisIt	O
was	O
developed	O
by	O
the	O
Department	O
of	O
Energy	O
(	O
DOE	O
)	O
Advanced	B-General_Concept
Simulation	I-General_Concept
and	I-General_Concept
Computing	I-General_Concept
Initiative	I-General_Concept
(	O
ASCI	O
)	O
to	O
visualize	O
and	O
analyze	O
the	O
results	O
of	O
terascale	O
simulations	O
.	O
</s>
<s>
It	O
was	O
developed	O
as	O
a	O
framework	O
for	O
adding	O
custom	O
capabilities	O
and	O
rapidly	O
deploying	O
new	O
visualization	B-Application
technologies	O
.	O
</s>
<s>
VisIt	O
is	O
now	O
supported	O
by	O
the	O
DOE	O
's	O
SciDAC	O
(	O
Scientific	O
Discovery	O
Through	O
Advanced	O
Computing	O
)	O
program	O
to	O
assist	O
with	O
analysis	O
and	O
visualization	B-Application
of	O
the	O
large	O
datasets	O
generated	O
by	O
open	O
scientific	O
computing	O
.	O
</s>
<s>
Since	O
VisIt	O
is	O
open	O
source	O
and	O
released	O
under	O
the	O
BSD	B-Operating_System
license	I-Operating_System
,	O
many	O
others	O
have	O
made	O
contributions	O
as	O
well	O
.	O
</s>
<s>
model	O
and	O
many	O
of	O
its	O
visualization	B-Application
algorithms	O
.	O
</s>
<s>
It	O
has	O
been	O
ported	O
to	O
Windows	B-Application
,	O
Mac	B-Device
,	O
and	O
many	O
Unix	B-Operating_System
variants	I-Operating_System
,	O
including	O
AIX	B-Application
,	O
</s>
<s>
IRIX	B-Operating_System
,	O
Solaris	B-Application
,	O
Tru64	B-Operating_System
,	O
and	O
Linux	B-Application
,	O
including	O
ports	O
for	O
SGI	O
's	O
Altix	B-Architecture
,	O
</s>
<s>
Cray	O
's	O
XT4	B-Device
,	O
and	O
many	O
commodity	O
clusters	B-Architecture
.	O
</s>
<s>
The	O
basic	O
design	O
is	O
a	O
client	B-Operating_System
–	I-Operating_System
server	I-Operating_System
model	I-Operating_System
,	O
where	O
the	O
server	O
is	O
parallelized	B-Operating_System
.	O
</s>
<s>
allowing	O
for	O
in	O
situ	O
visualization	B-Application
and	O
analysis	O
.	O
</s>
<s>
primary	O
user	B-Application
interface	I-Application
abstractions	O
and	O
there	O
are	O
many	O
examples	O
of	O
each	O
.	O
</s>
<s>
including	O
automatic	O
generation	O
of	O
Qt	B-Language
and	O
Python	B-Language
user	B-Application
interfaces	I-Application
.	O
</s>
<s>
a	O
distributed	B-Architecture
project	O
being	O
developed	O
by	O
several	O
groups	O
.	O
</s>
<s>
Has	O
rich	O
feature	O
set	O
for	O
scalar	O
,	O
vector	O
,	O
and	O
tensor	O
field	O
visualization	B-Application
.	O
</s>
<s>
VisIt	O
handles	O
2D	B-Algorithm
and	O
3D	O
data	O
equally	O
well	O
.	O
</s>
<s>
Provides	O
qualitative	O
and	O
quantitative	O
visualization	B-Application
and	O
analysis	O
.	O
</s>
<s>
VisIt	O
provides	O
support	O
for	O
a	O
wide	O
range	O
of	O
computational	O
meshes	O
,	O
including	O
two	O
-	O
and	O
three-dimensional	O
point	O
,	O
rectilinear	O
,	O
curvilinear	O
,	O
and	O
unstructured	B-Algorithm
meshes	O
.	O
</s>
<s>
In	O
addition	O
,	O
VisIt	O
supports	O
structured	O
AMR	B-Algorithm
meshes	O
and	O
CSG	O
meshes	O
.	O
</s>
<s>
Powerful	O
,	O
full-featured	O
graphical	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
VisIt	O
's	O
graphical	B-Application
user	I-Application
interface	I-Application
allows	O
novice	O
users	O
to	O
quickly	O
get	O
started	O
visualizing	O
their	O
data	O
,	O
as	O
well	O
as	O
allowing	O
power	O
users	O
access	O
to	O
advanced	O
features	O
.	O
</s>
<s>
Parallel	B-Operating_System
and	O
distributed	B-Architecture
architecture	O
.	O
</s>
<s>
VisIt	O
employs	O
a	O
distributed	B-Architecture
and	O
parallel	B-Operating_System
architecture	I-Operating_System
in	O
order	O
to	O
handle	O
extremely	O
large	O
data	O
sets	O
interactively	O
.	O
</s>
<s>
VisIt	O
's	O
rendering	O
and	O
data	B-General_Concept
processing	I-General_Concept
capabilities	O
are	O
split	O
into	O
viewer	O
and	O
engine	O
components	O
that	O
may	O
be	O
distributed	B-Architecture
across	O
multiple	O
machines	O
:	O
</s>
<s>
Viewer	O
is	O
responsible	O
for	O
rendering	O
and	O
is	O
typically	O
run	O
on	O
a	O
local	O
desktop	O
or	O
visualization	B-Application
server	O
so	O
that	O
it	O
can	O
leverage	O
the	O
extremely	O
powerful	O
graphics	B-Device
cards	I-Device
.	O
</s>
<s>
Engine	O
is	O
responsible	O
for	O
the	O
bulk	O
of	O
the	O
data	B-General_Concept
processing	I-General_Concept
and	O
input/output	B-General_Concept
and	O
is	O
typically	O
run	O
on	O
a	O
remote	O
machine	O
where	O
the	O
data	O
is	O
located	O
.	O
</s>
<s>
This	O
eliminates	O
the	O
need	O
to	O
move	O
the	O
data	O
and	O
makes	O
high-end	O
compute	O
and	O
I/O	B-General_Concept
resources	O
available	O
to	O
it	O
.	O
</s>
<s>
The	O
engine	O
can	O
be	O
run	O
serially	B-Operating_System
on	O
a	O
single	O
processor	O
or	O
in	O
parallel	B-Operating_System
on	O
thousands	O
of	O
processors	O
.	O
</s>
<s>
Interfaces	O
with	O
C++	B-Language
,	O
Python	B-Language
,	O
and	O
Java	B-Language
.	O
</s>
<s>
The	O
C++	B-Language
and	O
Java	B-Language
interfaces	O
make	O
it	O
possible	O
to	O
provide	O
alternate	O
user	B-Application
interfaces	I-Application
for	O
VisIt	O
or	O
allow	O
existing	O
C++	B-Language
or	O
Java	B-Language
applications	O
to	O
add	O
visualization	B-Application
support	O
.	O
</s>
<s>
The	O
Python	B-Language
scripting	B-Language
interface	O
gives	O
users	O
the	O
ability	O
to	O
batch	B-General_Concept
process	I-General_Concept
data	O
using	O
a	O
scripting	B-Language
language	I-Language
.	O
</s>
<s>
Extensible	B-Architecture
with	O
dynamically	B-Operating_System
loaded	I-Operating_System
plug-ins	B-Application
.	O
</s>
<s>
VisIt	O
achieves	O
extensibility	B-Architecture
through	O
the	O
use	O
of	O
dynamically	B-Operating_System
loaded	I-Operating_System
plugins	B-Application
.	O
</s>
<s>
All	O
of	O
VisIt	O
's	O
plots	O
,	O
operators	O
,	O
and	O
database	O
readers	O
are	O
implemented	O
as	O
plugins	B-Application
and	O
are	O
loaded	O
at	O
run-time	B-Library
from	O
the	O
plugin	B-Application
directory	O
.	O
</s>
<s>
New	O
plugins	B-Application
can	O
be	O
added	O
simply	O
by	O
installing	O
them	O
in	O
this	O
directory	O
.	O
</s>
<s>
VisIt	O
comes	O
with	O
a	O
graphical	O
plugin	B-Application
creation	O
tool	O
,	O
which	O
greatly	O
simplifies	O
the	O
process	O
of	O
creating	O
new	O
plugins	B-Application
.	O
</s>
