<s>
A	O
powerwall	B-Device
is	O
a	O
large	O
,	O
ultra-high-resolution	O
display	B-Device
that	O
is	O
constructed	O
of	O
a	O
matrix	O
of	O
other	O
displays	O
,	O
which	O
may	O
be	O
either	O
monitors	B-Device
or	O
projectors	B-Application
.	O
</s>
<s>
It	O
is	O
important	O
to	O
differentiate	O
between	O
powerwalls	B-Device
and	O
displays	O
that	O
are	O
just	O
large	O
,	O
for	O
example	O
,	O
the	O
single	O
projector	B-Application
display	B-Device
used	O
in	O
many	O
lecture	O
theatres	O
.	O
</s>
<s>
These	O
displays	O
rarely	O
have	O
a	O
resolution	O
higher	O
than	O
pixels	B-Algorithm
,	O
and	O
so	O
present	O
the	O
same	O
amount	O
of	O
information	O
as	O
on	O
a	O
standard	O
desktop	O
display	B-Device
.	O
</s>
<s>
With	O
Powerwall	B-Device
displays	O
,	O
users	O
can	O
view	O
the	O
display	B-Device
from	O
a	O
distance	O
and	O
see	O
an	O
overview	O
of	O
the	O
data	O
(	O
context	O
)	O
,	O
but	O
can	O
also	O
move	O
to	O
within	O
arm	O
’s	O
length	O
and	O
see	O
data	O
in	O
great	O
detail	O
(	O
focus	O
)	O
.	O
</s>
<s>
This	O
technique	O
of	O
moving	O
around	O
the	O
display	B-Device
is	O
known	O
as	O
physical	O
navigation	O
,	O
and	O
can	O
help	O
users	O
to	O
better	O
understand	O
their	O
data	O
.	O
</s>
<s>
The	O
first	O
Powerwall	B-Device
display	B-Device
was	O
installed	O
at	O
the	O
University	O
of	O
Minnesota	O
in	O
1994	O
.	O
</s>
<s>
It	O
was	O
made	O
of	O
four	O
rear-projection	O
displays	O
,	O
providing	O
a	O
resolution	O
of	O
7.8	O
million	O
pixels	B-Algorithm
(	O
pixels	B-Algorithm
)	O
.	O
</s>
<s>
Increases	O
in	O
graphic	O
display	B-Device
power	O
,	O
combined	O
with	O
decreases	O
in	O
hardware	O
costs	O
,	O
means	O
that	O
less	O
hardware	O
is	O
required	O
to	O
drive	O
such	O
displays	O
.	O
</s>
<s>
In	O
2006	O
,	O
a	O
50	O
–	O
60	O
mega-pixel	O
Powerwall	B-Device
display	B-Device
required	O
a	O
cluster	O
of	O
seven	O
machines	O
to	O
drive	O
it	O
,	O
in	O
2012	O
the	O
same	O
display	B-Device
could	O
be	O
driven	O
by	O
a	O
single	O
machine	O
with	O
three	O
graphics	B-Device
cards	I-Device
,	O
and	O
in	O
2015	O
it	O
could	O
be	O
driven	O
by	O
a	O
single	O
graphics	B-Device
card	I-Device
alone	O
.	O
</s>
<s>
Rather	O
than	O
seeing	O
a	O
decrease	O
in	O
the	O
use	O
of	O
PC	O
clusters	O
as	O
a	O
result	O
of	O
this	O
,	O
we	O
are	O
instead	O
seeing	O
cluster-driven	O
Powerwall	B-Device
displays	O
with	O
even	O
higher	O
resolutions	O
.	O
</s>
<s>
Currently	O
,	O
the	O
highest	O
resolution	O
display	B-Device
in	O
the	O
world	O
is	O
the	O
Reality	O
Deck	O
,	O
running	O
at	O
1.5	O
billion	O
pixels	B-Algorithm
,	O
powered	O
by	O
a	O
cluster	O
of	O
18	O
nodes	O
.	O
</s>
<s>
Both	O
software	O
and	O
hardware	O
techniques	O
have	O
been	O
proposed	O
to	O
aid	O
with	O
Powerwall	B-Device
interaction	O
.	O
</s>
<s>
Touch	B-Application
interfaces	I-Application
also	O
support	O
collaboration	O
,	O
and	O
increasingly	O
multi-touch	O
interfaces	O
are	O
being	O
overlaid	O
on	O
top	O
of	O
large	O
displays	O
.	O
</s>
<s>
The	O
physical	O
size	O
of	O
the	O
display	B-Device
,	O
however	O
,	O
can	O
leave	O
users	O
prone	O
to	O
fatigue	O
.	O
</s>
<s>
Mobile	O
devices	O
such	O
as	O
tablets	B-Device
can	O
be	O
used	O
as	O
interaction	O
devices	O
,	O
but	O
the	O
secondary	O
screen	O
can	O
distract	O
users’	O
attention	O
.	O
</s>
<s>
It	O
has	O
been	O
found	O
that	O
this	O
issue	O
can	O
be	O
addressed	O
by	O
adding	O
physical	O
widgets	O
to	O
the	O
tablet	B-Device
’s	O
screen	O
.	O
</s>
<s>
In	O
the	O
field	O
of	O
medical	B-Application
visualisation	I-Application
,	O
Powerwall	B-Device
displays	O
have	O
been	O
used	O
to	O
render	O
high-resolution	O
,	O
digitally	O
scanned	O
histology	O
slides	O
,	O
where	O
the	O
high	O
pixel	B-Algorithm
count	O
increases	O
the	O
volume	O
of	O
data	O
that	O
is	O
rendered	O
at	O
any	O
one	O
time	O
,	O
and	O
the	O
context	O
offered	O
by	O
the	O
size	O
of	O
the	O
display	B-Device
provides	O
a	O
spatial	O
reference	O
,	O
aiding	O
navigation	O
through	O
the	O
visualization	O
.	O
</s>
<s>
The	O
same	O
principal	O
can	O
also	O
be	O
said	O
for	O
geographical	O
data	O
such	O
as	O
maps	O
,	O
where	O
it	O
has	O
been	O
found	O
that	O
the	O
large	O
display	B-Device
real	O
estate	O
increases	O
performance	O
for	O
searching	O
and	O
route-tracing	O
.	O
</s>
<s>
Rather	O
than	O
flooding	O
the	O
large	O
display	B-Device
real	O
estate	O
with	O
data	O
,	O
tools	O
such	O
as	O
ForceSPIRE	O
make	O
use	O
of	O
semantic	O
interaction	O
to	O
enable	O
analysts	O
to	O
spatially	O
cluster	O
data	O
.	O
</s>
<s>
Research	O
on	O
collaboration	O
with	O
Powerwall	B-Device
displays	O
is	O
related	O
to	O
that	O
of	O
tabletops	O
,	O
which	O
suggests	O
that	O
partitioning	O
the	O
display	B-Device
space	O
is	O
crucial	O
to	O
efficient	O
collaboration	O
,	O
and	O
that	O
distinct	O
territories	O
may	O
be	O
identified	O
in	O
the	O
spatial	O
layout	O
of	O
information	O
.	O
</s>
<s>
A	O
recent	O
study	O
found	O
that	O
during	O
a	O
collaborative	O
sensemaking	O
session	O
in	O
front	O
of	O
a	O
multi-touch	O
Powerwal	O
display	B-Device
,	O
the	O
ability	O
to	O
physically	O
navigate	O
allowed	O
users	O
to	O
fluidly	O
shift	O
between	O
shared	O
and	O
personal	O
spaces	O
.	O
</s>
