<s>
Interactive	B-Application
Visual	I-Application
Analysis	I-Application
(	O
IVA	O
)	O
is	O
a	O
set	O
of	O
techniques	O
for	O
combining	O
the	O
computational	O
power	O
of	O
computers	O
with	O
the	O
perceptive	O
and	O
cognitive	O
capabilities	O
of	O
humans	O
,	O
in	O
order	O
to	O
extract	O
knowledge	O
from	O
large	O
and	O
complex	O
datasets	O
.	O
</s>
<s>
The	O
techniques	O
rely	O
heavily	O
on	O
user	O
interaction	O
and	O
the	O
human	O
visual	O
system	O
,	O
and	O
exist	O
in	O
the	O
intersection	O
between	O
visual	B-Application
analytics	I-Application
and	O
big	B-Application
data	I-Application
.	O
</s>
<s>
It	O
is	O
a	O
branch	O
of	O
data	B-Application
visualization	I-Application
.	O
</s>
<s>
IVA	O
is	O
a	O
suitable	O
technique	O
for	O
analyzing	O
high-dimensional	O
data	O
that	O
has	O
a	O
large	O
number	O
of	O
data	O
points	O
,	O
where	O
simple	O
graphing	O
and	O
non-interactive	B-General_Concept
techniques	O
give	O
an	O
insufficient	O
understanding	O
of	O
the	O
information	O
.	O
</s>
<s>
Focus	B-General_Concept
+	I-General_Concept
Context	I-General_Concept
visualization	I-General_Concept
and	O
its	O
related	O
techniques	O
date	O
back	O
to	O
the	O
1970s	O
.	O
</s>
<s>
Early	O
attempts	O
at	O
combining	O
these	O
techniques	O
for	O
Interactive	B-Application
Visual	I-Application
Analysis	I-Application
occur	O
in	O
the	O
WEAVE	O
visualization	O
system	O
for	O
cardiac	O
simulation	O
in	O
the	O
year	O
2000	O
.	O
</s>
<s>
The	O
objective	O
of	O
Interactive	B-Application
Visual	I-Application
Analysis	I-Application
is	O
to	O
discover	O
information	O
in	O
data	O
which	O
is	O
not	O
readily	O
apparent	O
.	O
</s>
<s>
The	O
views	O
are	O
usually	O
among	O
the	O
common	O
tools	O
of	O
information	B-Application
visualization	I-Application
,	O
such	O
as	O
histograms	B-Algorithm
,	O
scatterplots	B-Application
or	O
parallel	B-Application
coordinates	I-Application
,	O
but	O
using	O
volume	O
rendered	O
views	O
is	O
also	O
possible	O
if	O
this	O
is	O
appropriate	O
for	O
the	O
data	O
.	O
</s>
<s>
This	O
technique	O
,	O
which	O
intuitively	O
allows	O
exploration	O
of	O
higher-dimensional	O
properties	O
of	O
the	O
data	O
,	O
is	O
known	O
as	O
linking	B-Application
and	I-Application
brushing	I-Application
.	O
</s>
<s>
For	O
instance	O
,	O
when	O
examining	O
a	O
tumor	O
in	O
a	O
Magnetic	B-Algorithm
resonance	I-Algorithm
imaging	I-Algorithm
dataset	O
,	O
the	O
tissue	O
surrounding	O
the	O
tumor	O
might	O
also	O
be	O
of	O
some	O
interest	O
to	O
the	O
operator	O
.	O
</s>
<s>
Interactive	B-Application
Visual	I-Application
Analysis	I-Application
is	O
an	O
iterative	O
process	O
.	O
</s>
<s>
The	O
user	O
brushes	O
a	O
histogram	B-Algorithm
of	O
temperature	O
distribution	O
,	O
and	O
discovers	O
that	O
one	O
specific	O
part	O
of	O
one	O
cylinder	O
has	O
dangerously	O
high	O
temperatures	O
.	O
</s>
<s>
This	O
could	O
be	O
verified	O
by	O
brushing	O
the	O
same	O
region	O
in	O
all	O
other	O
cylinders	O
and	O
seeing	O
in	O
the	O
temperature	O
histogram	B-Algorithm
that	O
these	O
cylinders	O
also	O
have	O
higher	O
temperatures	O
than	O
expected	O
.	O
</s>
<s>
The	O
most	O
simple	O
form	O
of	O
IVA	O
is	O
the	O
base	O
level	O
which	O
consists	O
of	O
brushing	B-Application
and	I-Application
linking	I-Application
.	O
</s>
<s>
Brushing	B-Application
and	I-Application
linking	I-Application
with	O
logical	O
combination	O
of	O
brushes	O
is	O
a	O
more	O
advanced	O
form	O
of	O
IVA	O
.	O
</s>
<s>
After	O
detection	O
of	O
higher-order	O
features	O
,	O
the	O
calculated	O
attributes	O
would	O
be	O
connected	O
to	O
the	O
original	O
data	O
set	O
and	O
subjected	O
to	O
the	O
normal	O
technique	O
of	O
linking	B-Application
and	I-Application
brushing	I-Application
.	O
</s>
<s>
The	O
"	O
linking	B-Application
and	I-Application
brushing	I-Application
"	O
(	O
selection	O
)	O
concept	O
of	O
IVA	O
can	O
be	O
used	O
between	O
different	O
types	O
of	O
variables	O
in	O
the	O
dataset	O
.	O
</s>
<s>
a	O
simple	O
scatterplot	B-Application
.	O
</s>
<s>
Concepts	O
from	O
Interactive	B-Application
Visual	I-Application
Analysis	I-Application
have	O
been	O
implemented	O
in	O
multiple	O
software	O
packages	O
,	O
both	O
for	O
researchers	O
and	O
commercial	O
purposes	O
.	O
</s>
