<s>
A	O
virtual	B-Device
reality	I-Device
headset	I-Device
(	O
or	O
VR	B-Device
headset	I-Device
)	O
is	O
a	O
head-mounted	O
device	O
that	O
provides	O
virtual	B-Application
reality	I-Application
for	O
the	O
wearer	O
.	O
</s>
<s>
VR	B-Device
headsets	I-Device
are	O
widely	O
used	O
with	O
VR	O
video	O
games	O
but	O
they	O
are	O
also	O
used	O
in	O
other	O
applications	O
,	O
including	O
simulators	O
and	O
trainers	O
.	O
</s>
<s>
VR	B-Device
headsets	I-Device
typically	O
include	O
a	O
stereoscopic	B-Algorithm
display	I-Algorithm
(	O
providing	O
separate	O
images	O
for	O
each	O
eye	O
)	O
,	O
stereo	O
sound	O
,	O
and	O
sensors	O
like	O
accelerometers	O
and	O
gyroscopes	B-Application
for	O
tracking	O
the	O
pose	B-Operating_System
of	O
the	O
user	O
's	O
head	O
to	O
match	O
the	O
orientation	O
of	O
the	O
virtual	O
camera	O
with	O
the	O
user	O
's	O
eye	O
positions	O
in	O
the	O
real	O
world	O
.	O
</s>
<s>
Some	O
VR	B-Device
headsets	I-Device
also	O
have	O
eye-tracking	B-General_Concept
sensors	O
and	O
gaming	B-Device
controllers	I-Device
.	O
</s>
<s>
The	O
VR	B-Device
glasses	I-Device
use	O
a	O
technology	O
called	O
head-tracking	O
,	O
which	O
changes	O
the	O
field	O
of	O
vision	O
as	O
a	O
person	O
turns	O
their	O
head	O
.	O
</s>
<s>
The	O
Sega	B-Device
VR	I-Device
,	O
announced	O
in	O
1991	O
and	O
seen	O
in	O
early	O
1993	O
at	O
the	O
Winter	O
CES	O
,	O
was	O
never	O
released	O
for	O
consoles	O
,	O
but	O
was	O
utilized	O
for	O
the	O
Sega	O
VR-1	O
motion	O
simulator	O
arcade	O
attraction	O
in	O
1994	O
.	O
</s>
<s>
Another	O
early	O
VR	B-Device
headset	I-Device
,	O
the	O
Forte	B-Device
VFX1	I-Device
,	O
was	O
announced	O
at	O
CES	O
in	O
1994	O
.	O
</s>
<s>
The	O
VFX-1	O
has	O
stereoscopic	B-Algorithm
displays	I-Algorithm
,	O
3-axis	O
head-tracking	O
,	O
and	O
stereo	O
headphones	O
.	O
</s>
<s>
Sony	O
,	O
another	O
pioneer	O
,	O
released	O
the	O
Glasstron	B-Device
in	O
1997	O
,	O
which	O
has	O
an	O
optional	O
positional	O
sensor	O
,	O
allowing	O
the	O
wearer	O
to	O
view	O
the	O
surroundings	O
,	O
with	O
the	O
perspective	O
moving	O
as	O
the	O
user	O
's	O
head	O
moves	O
,	O
giving	O
a	O
deep	O
sense	O
of	O
immersion	O
.	O
</s>
<s>
These	O
VR	B-Device
headsets	I-Device
gave	O
MechWarrior	B-Application
2	I-Application
players	O
a	O
new	O
visual	O
perspective	O
of	O
seeing	O
the	O
battlefield	O
from	O
inside	O
the	O
cockpit	O
of	O
their	O
craft	O
.	O
</s>
<s>
In	O
2012	O
,	O
a	O
crowdfunding	O
campaign	O
began	O
for	O
a	O
VR	B-Device
headset	I-Device
known	O
as	O
Oculus	B-Device
Rift	I-Device
;	O
the	O
project	O
was	O
led	O
by	O
several	O
prominent	O
video	O
game	O
developers	O
,	O
including	O
Carmack	O
who	O
later	O
became	O
the	O
company	O
's	O
CTO	O
.	O
</s>
<s>
In	O
March	O
2014	O
,	O
the	O
project	O
's	O
parent	O
company	O
Oculus	B-Application
VR	I-Application
was	O
acquired	O
by	O
Facebook	B-Application
for	O
$2	O
billion	O
.	O
</s>
<s>
The	O
final	O
consumer-oriented	O
release	O
of	O
Oculus	B-Device
Rift	I-Device
began	O
shipping	O
on	O
28	O
March	O
2016	O
.	O
</s>
<s>
In	O
March	O
2014	O
,	O
Sony	O
demonstrated	O
a	O
prototype	O
headset	O
for	O
PlayStation	B-Operating_System
4	I-Operating_System
,	O
which	O
was	O
later	O
named	O
PlayStation	B-Device
VR	I-Device
.	O
</s>
<s>
In	O
2014	O
,	O
Valve	O
demonstrated	O
some	O
headset	O
prototypes	O
,	O
which	O
led	O
to	O
a	O
partnership	O
with	O
HTC	B-Application
to	O
produce	O
the	O
Vive	O
,	O
which	O
focuses	O
on	O
"	O
room	O
scale	O
"	O
VR	O
environments	O
that	O
users	O
can	O
naturally	O
navigate	O
within	O
and	O
interact	O
with	O
.	O
</s>
<s>
The	O
Vive	O
was	O
released	O
in	O
April	O
2016	O
and	O
PlayStation	B-Device
VR	I-Device
in	O
October	O
2016	O
.	O
</s>
<s>
Virtual	B-Device
reality	I-Device
headsets	I-Device
and	O
viewers	O
have	O
also	O
been	O
designed	O
for	O
smartphones	B-Application
.	O
</s>
<s>
Unlike	O
headsets	O
with	O
integrated	O
displays	O
,	O
these	O
units	O
are	O
essentially	O
enclosures	O
which	O
a	O
smartphone	B-Application
can	O
be	O
inserted	O
into	O
.	O
</s>
<s>
VR	O
content	O
is	O
viewed	O
from	O
the	O
screen	O
of	O
the	O
device	O
itself	O
through	O
lenses	O
acting	O
as	O
a	O
stereoscope	B-Algorithm
,	O
rather	O
than	O
using	O
dedicated	O
internal	O
displays	O
.	O
</s>
<s>
Google	O
released	O
a	O
series	O
of	O
specifications	O
and	O
associated	O
DIY	O
kits	O
for	O
virtual	B-Application
reality	I-Application
viewers	O
known	O
as	O
Google	B-Device
Cardboard	I-Device
;	O
these	O
viewers	O
are	O
capable	O
of	O
being	O
constructed	O
using	O
low-cost	O
materials	O
(	O
and	O
a	O
smartphone	B-Application
with	O
a	O
gyroscope	B-Application
)	O
,	O
such	O
as	O
cardboard	O
(	O
hence	O
the	O
naming	O
)	O
.	O
</s>
<s>
Samsung	O
Electronics	O
partnered	O
with	O
Oculus	B-Application
VR	I-Application
to	O
co-develop	O
the	O
Samsung	B-Device
Gear	I-Device
VR	I-Device
(	O
which	O
is	O
only	O
compatible	O
with	O
recent	O
Samsung	B-Operating_System
Galaxy	I-Operating_System
devices	O
)	O
,	O
while	O
LG	O
Electronics	O
developed	O
a	O
headset	O
with	O
dedicated	O
displays	O
for	O
its	O
LG	B-Application
G5	I-Application
smartphone	B-Application
known	O
as	O
LG	O
360	O
VR	O
.	O
</s>
<s>
Asian	O
hardware	O
manufacturers	O
like	O
Xion	O
and	O
Kolke	O
have	O
developed	O
inexpensive	O
virtual	B-Device
reality	I-Device
headsets	I-Device
.	O
</s>
<s>
In	O
2017	O
,	O
Chinese	O
company	O
Tencent	O
announced	O
it	O
was	O
preparing	O
to	O
launch	O
its	O
virtual	B-Device
reality	I-Device
headset	I-Device
that	O
year	O
.	O
</s>
<s>
In	O
2019	O
,	O
Oculus	B-Application
and	O
PlayStation	B-Device
VR	I-Device
dominated	O
the	O
VR	B-Device
headset	I-Device
market	O
.	O
</s>
<s>
In	O
June	O
2019	O
,	O
Valve	O
released	O
their	O
own	O
headset	O
,	O
the	O
Valve	B-Device
Index	I-Device
,	O
without	O
a	O
partnership	O
with	O
HTC	B-Application
.	O
</s>
<s>
Virtual	B-Device
reality	I-Device
headsets	I-Device
have	O
significantly	O
higher	O
requirements	O
for	O
latencythe	O
time	O
it	O
takes	O
from	O
a	O
change	O
in	O
input	O
to	O
have	O
a	O
visual	O
effectthan	O
ordinary	O
video	O
games	O
.	O
</s>
<s>
If	O
the	O
system	O
is	O
too	O
sluggish	O
to	O
react	O
to	O
head	O
movement	O
,	O
then	O
it	O
can	O
cause	O
the	O
user	O
to	O
experience	O
virtual	B-Application
reality	I-Application
sickness	I-Application
,	O
a	O
kind	O
of	O
motion	O
sickness	O
.	O
</s>
<s>
The	O
graphics	B-Architecture
processing	I-Architecture
unit	I-Architecture
(	O
GPU	B-Architecture
)	O
also	O
needs	O
to	O
be	O
powerful	O
enough	O
to	O
render	O
the	O
required	O
amount	O
of	O
frames	O
.	O
</s>
<s>
Oculus	B-Application
cited	O
the	O
limited	O
processing	O
power	O
of	O
Xbox	B-Device
One	I-Device
and	O
PlayStation	B-Operating_System
4	I-Operating_System
as	O
the	O
reason	O
why	O
they	O
targeted	O
the	O
PC	O
gaming	O
market	O
with	O
their	O
first	O
devices	O
.	O
</s>
<s>
Foveated	B-Algorithm
rendering	I-Algorithm
is	O
a	O
new	O
technique	O
to	O
reduce	O
the	O
rendering	O
workload	O
.	O
</s>
<s>
It	O
uses	O
eye	B-General_Concept
tracking	I-General_Concept
hardware	O
to	O
determine	O
at	O
what	O
point	O
the	O
user	O
is	O
looking	O
and	O
reduces	O
rendering	O
resolution	B-General_Concept
farther	O
from	O
the	O
user	O
's	O
gaze	O
.	O
</s>
<s>
The	O
image	O
clarity	O
depends	O
on	O
the	O
display	B-General_Concept
resolution	I-General_Concept
,	O
optic	O
quality	O
,	O
refresh	O
rate	O
,	O
and	O
the	O
field	O
of	O
view	O
.	O
</s>
<s>
Because	O
virtual	B-Device
reality	I-Device
headsets	I-Device
stretch	O
a	O
single	O
display	O
across	O
a	O
wide	O
field	O
of	O
view	O
(	O
up	O
to	O
110°	O
for	O
some	O
devices	O
according	O
to	O
manufacturers	O
)	O
,	O
the	O
magnification	O
factor	O
makes	O
flaws	O
in	O
display	O
technology	O
much	O
more	O
apparent	O
.	O
</s>
<s>
One	O
issue	O
is	O
the	O
so-called	O
screen-door	B-General_Concept
effect	I-General_Concept
,	O
where	O
the	O
gaps	O
between	O
rows	O
and	O
columns	O
of	O
pixels	B-Algorithm
become	O
visible	O
,	O
kind	O
of	O
like	O
looking	O
through	O
a	O
screen	O
door	O
.	O
</s>
<s>
Fresnel	O
lenses	O
are	O
commonly	O
used	O
in	O
virtual	B-Device
reality	I-Device
headsets	I-Device
due	O
to	O
their	O
compactness	O
and	O
lightweight	O
structure	O
.	O
</s>
<s>
Motion	O
capture	O
was	O
used	O
by	O
Nintendo	B-Operating_System
's	I-Operating_System
Wii	I-Operating_System
game	O
console	O
by	O
having	O
the	O
player	O
use	O
a	O
controller	O
to	O
interact	O
with	O
the	O
game	O
of	O
their	O
choice	O
,	O
often	O
being	O
sports	O
games	O
.	O
</s>
<s>
Soon	O
after	O
the	O
release	O
of	O
Nintendo	B-Operating_System
's	I-Operating_System
Wii	I-Operating_System
,	O
Microsoft	O
's	O
Xbox	B-Protocol
received	O
a	O
full	O
body	O
reading	O
system	O
called	O
Kinect	B-Algorithm
compatible	O
with	O
Valve	O
's	O
modding	O
system	O
.	O
</s>
<s>
Later	O
,	O
Sony	O
released	O
a	O
similar	O
motion	O
capture	O
device	O
for	O
their	O
PlayStation	B-Device
named	O
the	O
PlayStation	B-Device
Move	I-Device
.	O
</s>
<s>
These	O
gaming	O
devices	O
use	O
motion	O
capture	O
to	O
control	O
avatars	B-Application
within	O
a	O
game	O
,	O
where	O
the	O
player	O
's	O
movements	O
are	O
copied	O
by	O
the	O
avatar	B-Application
to	O
complete	O
the	O
game	O
.	O
</s>
<s>
This	O
means	O
that	O
the	O
player	O
is	O
not	O
truly	O
engaged	O
in	O
the	O
virtual	B-Application
reality	I-Application
world	O
.	O
</s>
<s>
Virtual	B-Device
reality	I-Device
headsets	I-Device
are	O
being	O
currently	O
used	O
as	O
a	O
means	O
to	O
train	O
medical	O
students	O
for	O
surgery	O
.	O
</s>
<s>
Now	O
,	O
with	O
the	O
use	O
of	O
VR	B-Device
headsets	I-Device
,	O
students	O
can	O
watch	O
surgical	O
procedures	O
from	O
the	O
perspective	O
of	O
the	O
lead	O
surgeon	O
without	O
missing	O
essential	O
parts	O
.	O
</s>
<s>
VR	B-Device
headset	I-Device
mounted	O
smartphones	B-Application
have	O
been	O
used	O
to	O
capture	O
high	B-General_Concept
quality	I-General_Concept
videos	O
and	O
images	O
of	O
the	O
retina	O
for	O
documenting	O
peripheral	O
retinal	O
lesions	O
.	O
</s>
<s>
Virtual	B-Device
reality	I-Device
headsets	I-Device
have	O
been	O
used	O
by	O
the	O
United	O
States	O
Armed	O
Forces	O
.	O
</s>
<s>
The	O
virtual	B-Device
reality	I-Device
headset	I-Device
allows	O
the	O
military	O
personnel	O
to	O
interact	O
with	O
virtual	B-Application
reality	I-Application
people	O
to	O
make	O
it	O
feel	O
real	O
.	O
</s>
<s>
They	O
can	O
talk	O
to	O
one	O
another	O
and	O
do	O
varying	O
actions	O
to	O
make	O
the	O
virtual	B-Application
reality	I-Application
world	O
feel	O
like	O
they	O
are	O
actually	O
in	O
that	O
situation	O
.	O
</s>
<s>
Virtual	B-Device
reality	I-Device
headsets	I-Device
have	O
been	O
linked	O
to	O
rising	O
cases	O
of	O
rashes	O
,	O
swelling	O
,	O
burning	O
,	O
itching	O
,	O
hives	B-Application
,	O
and	O
bumps	O
.	O
</s>
<s>
On	O
27	O
July	O
2021	O
,	O
the	O
US	O
Consumer	O
Product	O
Safety	O
Commission	O
(	O
CPSC	O
)	O
and	O
Health	O
Canada	O
have	O
coordinated	O
a	O
recall	O
of	O
Facebook	B-Application
's	O
Oculus	B-General_Concept
Quest	I-General_Concept
2	I-General_Concept
after	O
5,716	O
reports	O
of	O
facial	O
skin	O
irritation	O
were	O
reported	O
with	O
45	O
cases	O
requiring	O
medical	O
attention	O
.	O
</s>
<s>
Facebook	B-Application
did	O
not	O
halt	O
Oculus	B-Application
sales	O
immediately	O
citing	O
data	O
that	O
only	O
"	O
0.01	O
%	O
of	O
people	O
using	O
Quest	B-General_Concept
2	I-General_Concept
"	O
had	O
serious	O
allergic	O
reactions	O
and	O
dermatological	O
and	O
toxicological	O
reports	O
came	O
out	O
negative	O
for	O
contaminants	O
that	O
could	O
be	O
causing	O
the	O
swollen	O
painful	O
rashes	O
upon	O
skin	O
contact	O
.	O
</s>
<s>
Facebook	B-Application
does	O
n't	O
know	O
the	O
origin	O
of	O
this	O
reaction	O
and	O
instead	O
they	O
sent	O
a	O
free	O
silicone	O
cover	O
to	O
cover	O
the	O
allergic	O
user	O
's	O
faces	O
.	O
</s>
<s>
Over	O
four	O
million	O
Oculus	B-Application
head	O
sets	O
have	O
been	O
recalled	O
.	O
</s>
<s>
Facebook	B-Application
's	O
VR	B-Device
headsets	I-Device
also	O
was	O
banned	O
from	O
Germany	O
in	O
September	O
2020	O
after	O
it	O
faced	O
criticism	O
from	O
the	O
German	O
Federal	O
Cartel	O
Office	O
(	O
Bundeskartellamt	O
)	O
for	O
requiring	O
its	O
users	O
to	O
have	O
valid	O
Facebook	B-Application
accounts	O
before	O
covering	O
their	O
head	O
with	O
the	O
Oculus	B-Application
.	O
</s>
<s>
Germany	O
has	O
one	O
of	O
the	O
world	O
's	O
leading	O
antitrust	O
agencies	O
and	O
Facebook	B-Application
's	O
ruling	O
raised	O
concerns	O
of	O
regulation	O
and	O
antitrust	O
monopolies	O
.	O
</s>
