<s>
Surface	B-Application
computing	I-Application
is	O
the	O
use	O
of	O
a	O
specialized	O
computer	O
GUI	B-Application
in	O
which	O
traditional	O
GUI	B-Application
elements	O
are	O
replaced	O
by	O
intuitive	O
,	O
everyday	O
objects	O
.	O
</s>
<s>
Instead	O
of	O
a	O
keyboard	B-Device
and	O
mouse	B-Device
,	O
the	O
user	O
interacts	O
with	O
a	O
surface	O
.	O
</s>
<s>
Typically	O
the	O
surface	O
is	O
a	O
touch-sensitive	B-Device
screen	I-Device
,	O
though	O
other	O
surface	O
types	O
like	O
non-flat	O
three-dimensional	O
objects	O
have	O
been	O
implemented	O
as	O
well	O
.	O
</s>
<s>
Major	O
computer	O
vendor	O
platforms	O
are	O
in	O
various	O
stages	O
of	O
release	O
:	O
the	O
iTable	O
by	O
PQLabs	O
,	O
Linux	B-Device
MPX	I-Device
,	O
the	O
Ideum	O
MT-50	O
,	O
interactive	O
bar	O
by	O
spinTOUCH	O
,	O
and	O
Microsoft	B-General_Concept
PixelSense	I-General_Concept
(	O
formerly	O
known	O
as	O
Microsoft	O
Surface	O
)	O
.	O
</s>
<s>
Surface	B-Application
computing	I-Application
employs	O
the	O
use	O
of	O
two	O
broad	O
categories	O
of	O
surface	O
types	O
,	O
flat	O
and	O
non-flat	O
.	O
</s>
<s>
This	O
is	O
the	O
most	O
common	O
form	O
of	O
surface	B-Application
computing	I-Application
in	O
the	O
commercial	O
space	O
as	O
seen	O
by	O
products	O
like	O
Microsoft	O
's	O
PixelSense	B-General_Concept
and	O
iTable	O
.	O
</s>
<s>
The	O
aforementioned	O
commercial	O
products	O
utilize	O
a	O
multi-touch	B-Application
LCD	B-Device
screen	I-Device
as	O
a	O
display	O
,	O
but	O
other	O
implementations	O
use	O
projectors	O
.	O
</s>
<s>
Part	O
of	O
the	O
appeal	O
of	O
two-dimensional	O
surface	B-Application
computing	I-Application
is	O
the	O
ease	O
and	O
reliability	O
of	O
interaction	O
.	O
</s>
<s>
While	O
most	O
work	O
with	O
surface	B-Application
computing	I-Application
has	O
been	O
done	O
with	O
flat	O
surfaces	O
,	O
non-flat	O
surfaces	O
have	O
become	O
an	O
interest	O
with	O
researchers	O
.	O
</s>
<s>
The	O
eventual	O
goal	O
of	O
surface	B-Application
computing	I-Application
itself	O
is	O
tied	O
to	O
the	O
notion	O
of	O
ubiquitous	B-Architecture
computing	I-Architecture
"	O
where	O
everyday	O
surfaces	O
in	O
our	O
environment	O
are	O
made	O
interactive	O
"	O
.	O
</s>
<s>
Including	O
a	O
third	O
dimension	O
to	O
surface	B-Application
computing	I-Application
presents	O
both	O
benefits	O
and	O
challenges	O
.	O
</s>
<s>
Displays	O
for	O
surface	B-Application
computing	I-Application
can	O
range	O
from	O
LCD	B-Device
and	O
projection	O
screens	O
to	O
physical	O
object	O
surfaces	O
.	O
</s>
<s>
A	O
wide	O
range	O
of	O
projectors	O
are	O
used	O
including	O
DLP	O
,	O
LCD	B-Device
,	O
and	O
LED	O
.	O
</s>
<s>
Various	O
methods	O
of	O
interaction	O
exist	O
in	O
surface	B-Application
computing	I-Application
.	O
</s>
<s>
The	O
most	O
common	O
method	O
of	O
which	O
is	O
touch	O
based	O
,	O
this	O
includes	O
single	O
and	O
multi-touch	B-Application
interactions	O
.	O
</s>
<s>
Other	O
interactions	O
exist	O
such	O
as	O
freehand	O
3D	B-General_Concept
interactions	I-General_Concept
that	O
depth-aware	O
cameras	O
can	O
sense	O
.	O
</s>
<s>
Depending	O
on	O
the	O
system	O
,	O
multi-touch	B-Application
gestures	O
,	O
such	O
as	O
pinch	B-Application
to	I-Application
zoom	I-Application
,	O
are	O
supported	O
.	O
</s>
<s>
For	O
sufficiently	O
large	O
surfaces	O
,	O
multi-touch	B-Application
gestures	O
can	O
extend	O
to	O
both	O
hands	O
,	O
and	O
even	O
multiple	O
sets	O
of	O
hands	O
in	O
multi-user	O
applications	O
.	O
</s>
<s>
Surface	B-Application
computing	I-Application
is	O
used	O
in	O
both	O
research	O
and	O
commercial	O
use	O
.	O
</s>
<s>
It	O
is	O
more	O
widely	O
known	O
commercially	O
in	O
products	O
such	O
as	O
the	O
iPad	B-Device
.	O
</s>
<s>
Although	O
tablets	O
like	O
the	O
iPad	B-Device
are	O
among	O
the	O
most	O
common	O
types	O
of	O
surface	B-Application
computing	I-Application
other	O
implementations	O
exist	O
,	O
such	O
as	O
HP	O
's	O
Sprout	B-Device
computer	O
.	O
</s>
<s>
In	O
research	O
,	O
surface	B-Application
computing	I-Application
has	O
been	O
used	O
to	O
help	O
develop	O
gestures	O
for	O
tabletop	O
implementations	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
exploration	O
of	O
other	O
surface	O
types	O
has	O
been	O
done	O
to	O
help	O
bring	O
surface	B-Application
computing	I-Application
to	O
many	O
other	O
surface	O
types	O
,	O
like	O
curved	O
and	O
spherical	O
surfaces	O
.	O
</s>
