<s>
Spatial	B-General_Concept
computing	I-General_Concept
was	O
defined	O
in	O
2003	O
by	O
Simon	O
Greenwold	O
,	O
as	O
"	O
human	O
interaction	O
with	O
a	O
machine	O
in	O
which	O
the	O
machine	O
retains	O
and	O
manipulates	O
referents	O
to	O
real	O
objects	O
and	O
spaces	O
"	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
consumer	O
virtual	B-Application
reality	I-Application
,	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
and	O
mixed	B-General_Concept
reality	I-General_Concept
,	O
companies	O
such	O
as	O
Microsoft	O
and	O
Magic	B-General_Concept
Leap	I-General_Concept
use	O
"	O
spatial	B-General_Concept
computing	I-General_Concept
"	O
in	O
reference	O
to	O
the	O
practice	O
of	O
using	O
physical	O
actions	O
(	O
head	O
and	O
body	O
movements	O
,	O
gestures	O
,	O
speech	O
)	O
as	O
inputs	B-General_Concept
for	O
interactive	O
digital	O
media	O
systems	O
,	O
with	O
perceived	O
3D	O
physical	O
space	O
as	O
the	O
canvas	O
for	O
video	O
,	O
audio	O
,	O
and	O
haptic	B-Device
outputs	B-General_Concept
.	O
</s>
<s>
It	O
is	O
also	O
tied	O
to	O
the	O
concept	O
of	O
'	O
digital	B-General_Concept
twins	I-General_Concept
 '	O
.	O
</s>
