<s>
A	O
structured-light	B-Algorithm
3D	I-Algorithm
scanner	I-Algorithm
is	O
a	O
3D	B-Algorithm
scanning	I-Algorithm
device	O
for	O
measuring	O
the	O
three-dimensional	O
shape	O
of	O
an	O
object	O
using	O
projected	B-General_Concept
light	I-General_Concept
patterns	I-General_Concept
and	O
a	O
camera	O
system	O
.	O
</s>
<s>
The	O
cameras	O
capture	O
these	O
images	O
and	O
send	O
them	O
to	O
the	O
3D	B-Algorithm
scanning	I-Algorithm
software	O
for	O
processing	O
.	O
</s>
<s>
Although	O
many	O
other	O
variants	O
of	O
structured	B-General_Concept
light	I-General_Concept
projection	O
are	O
possible	O
,	O
patterns	O
of	O
parallel	O
stripes	O
are	O
widely	O
used	O
.	O
</s>
<s>
Typically	O
,	O
there	O
is	O
no	O
means	O
of	O
modulating	O
individual	O
stripes	O
,	O
such	O
as	O
with	O
Gray	B-Device
codes	I-Device
.	O
</s>
<s>
The	O
projection	O
method	O
uses	O
incoherent	O
light	O
and	O
basically	O
works	O
like	O
a	O
video	B-Device
projector	I-Device
.	O
</s>
<s>
Patterns	O
are	O
usually	O
generated	O
by	O
passing	O
light	O
through	O
a	O
digital	O
spatial	O
light	O
modulator	O
,	O
typically	O
based	O
on	O
one	O
of	O
the	O
three	O
currently	O
most	O
widespread	O
digital	O
projection	O
technologies	O
,	O
transmissive	O
liquid	B-Device
crystal	I-Device
,	O
reflective	O
liquid	B-Device
crystal	I-Device
on	I-Device
silicon	I-Device
(	O
LCOS	B-Device
)	O
or	O
digital	B-General_Concept
light	I-General_Concept
processing	I-General_Concept
(	O
DLP	O
;	O
moving	O
micro	O
mirror	O
)	O
modulators	O
,	O
which	O
have	O
various	O
comparative	O
advantages	O
and	O
disadvantages	O
for	O
this	O
application	O
.	O
</s>
<s>
Patterns	O
generated	O
by	O
digital	O
display	O
projectors	O
have	O
small	O
discontinuities	O
due	O
to	O
the	O
pixel	B-Algorithm
boundaries	O
in	O
the	O
displays	O
.	O
</s>
<s>
Invisible	O
(	O
or	O
imperceptible	O
)	O
structured	B-General_Concept
light	I-General_Concept
uses	O
structured	B-General_Concept
light	I-General_Concept
without	O
interfering	O
with	O
other	O
computer	O
vision	O
tasks	O
for	O
which	O
the	O
projected	O
pattern	O
will	O
be	O
confusing	O
.	O
</s>
<s>
Geometric	O
distortions	O
by	O
optics	O
and	O
perspective	O
must	O
be	O
compensated	O
by	O
a	O
calibration	B-General_Concept
of	O
the	O
measuring	O
equipment	O
,	O
using	O
special	O
calibration	B-General_Concept
patterns	O
and	O
surfaces	O
.	O
</s>
<s>
Essentially	O
based	O
on	O
the	O
simple	O
geometric	O
properties	O
of	O
a	O
pinhole	B-Algorithm
camera	I-Algorithm
,	O
the	O
model	O
also	O
has	O
to	O
take	O
into	O
account	O
the	O
geometric	O
distortions	O
and	O
optical	O
aberration	O
of	O
projector	O
and	O
camera	O
lenses	O
.	O
</s>
<s>
The	O
parameters	O
of	O
the	O
camera	O
as	O
well	O
as	O
its	O
orientation	O
in	O
space	O
can	O
be	O
determined	O
by	O
a	O
series	O
of	O
calibration	B-General_Concept
measurements	O
,	O
using	O
photogrammetric	B-Application
bundle	B-General_Concept
adjustment	I-General_Concept
.	O
</s>
<s>
Another	O
common	O
method	O
projects	O
alternating	O
stripe	O
patterns	O
,	O
resulting	O
in	O
binary	O
Gray	B-Device
code	I-Device
sequences	O
identifying	O
the	O
number	O
of	O
each	O
individual	O
stripe	O
hitting	O
the	O
object	O
.	O
</s>
<s>
the	O
first	B-Algorithm
derivative	I-Algorithm
of	O
the	O
elevation	O
.	O
</s>
<s>
Stripe	O
frequency	O
and	O
phase	O
deliver	O
similar	O
cues	O
and	O
can	O
be	O
analyzed	O
by	O
a	O
Fourier	B-Algorithm
transform	I-Algorithm
.	O
</s>
<s>
In	O
many	O
practical	O
implementations	O
,	O
series	O
of	O
measurements	O
combining	O
pattern	O
recognition	O
,	O
Gray	B-Device
codes	I-Device
and	O
Fourier	B-Algorithm
transform	I-Algorithm
are	O
obtained	O
for	O
a	O
complete	O
and	O
unambiguous	O
reconstruction	O
of	O
shapes	O
.	O
</s>
<s>
Another	O
method	O
also	O
belonging	O
to	O
the	O
area	O
of	O
fringe	B-Algorithm
projection	I-Algorithm
has	O
been	O
demonstrated	O
,	O
utilizing	O
the	O
depth	O
of	O
field	O
of	O
the	O
camera	O
.	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
use	O
projected	O
patterns	O
primarily	O
as	O
a	O
means	O
of	O
structure	O
insertion	O
into	O
scenes	O
,	O
for	O
an	O
essentially	O
photogrammetric	B-Application
acquisition	O
.	O
</s>
<s>
The	O
optical	O
resolution	O
of	O
fringe	B-Algorithm
projection	I-Algorithm
methods	O
depends	O
on	O
the	O
width	O
of	O
the	O
stripes	O
used	O
and	O
their	O
optical	O
quality	O
.	O
</s>
<s>
Concerning	O
level	O
accuracy	O
,	O
interpolating	O
over	O
several	O
pixels	B-Algorithm
of	O
the	O
acquired	O
camera	O
image	O
can	O
yield	O
a	O
reliable	O
height	O
resolution	O
and	O
also	O
accuracy	O
,	O
down	O
to	O
1/50	O
pixel	B-Algorithm
.	O
</s>
<s>
The	O
3D	O
data	O
gathered	O
can	O
be	O
used	O
to	O
retrieve	O
CAD	B-Application
(	O
computer	B-Application
aided	I-Application
design	I-Application
)	O
data	O
and	O
models	O
from	O
existing	O
components	O
(	O
reverse	O
engineering	O
)	O
,	O
hand	O
formed	O
samples	O
or	O
sculptures	O
,	O
natural	O
objects	O
or	O
artifacts	O
.	O
</s>
<s>
These	O
methods	O
have	O
shown	O
promising	O
3D	B-Algorithm
scanning	I-Algorithm
results	O
for	O
traditionally	O
difficult	O
objects	O
,	O
such	O
as	O
highly	O
specular	O
metal	O
concavities	O
and	O
translucent	O
wax	O
candles	O
.	O
</s>
<s>
Although	O
several	O
patterns	O
have	O
to	O
be	O
taken	O
per	O
picture	O
in	O
most	O
structured	B-General_Concept
light	I-General_Concept
variants	O
,	O
high-speed	O
implementations	O
are	O
available	O
for	O
a	O
number	O
of	O
applications	O
,	O
for	O
example	O
:	O
</s>
<s>
Health	O
care	O
applications	O
,	O
such	O
as	O
live	O
measuring	O
of	O
human	B-Algorithm
body	I-Algorithm
shapes	I-Algorithm
or	O
the	O
micro	O
structures	O
of	O
human	O
skin	O
.	O
</s>
<s>
Industrial	O
Optical	O
Metrology	O
Systems	O
(	O
ATOS	O
)	O
from	O
GOM	O
GmbH	O
utilize	O
Structured	B-General_Concept
Light	I-General_Concept
technology	O
to	O
achieve	O
high	O
accuracy	O
and	O
scalability	O
in	O
measurements	O
.	O
</s>
<s>
These	O
systems	O
feature	O
self-monitoring	O
for	O
calibration	B-General_Concept
status	O
,	O
transformation	O
accuracy	O
,	O
environmental	O
changes	O
,	O
and	O
part	O
movement	O
to	O
ensure	O
high-quality	O
measuring	O
data	O
.	O
</s>
<s>
Google	B-Algorithm
Project	I-Algorithm
Tango	I-Algorithm
SLAM	O
(	O
Simultaneous	B-Application
localization	I-Application
and	I-Application
mapping	I-Application
)	O
using	O
depth	O
technologies	O
,	O
including	O
Structured	B-General_Concept
Light	I-General_Concept
,	O
Time	O
of	O
Flight	O
,	O
and	O
Stereo	O
.	O
</s>
<s>
srl	O
produces	O
a	O
3D	B-Algorithm
Scanner	I-Algorithm
utilizing	O
an	O
advanced	O
patented	O
technology	O
that	O
enables	O
3d	B-Algorithm
scanning	I-Algorithm
in	O
full	O
color	O
and	O
with	O
an	O
acquisition	O
time	O
of	O
a	O
few	O
microseconds	O
,	O
used	O
in	O
medical	O
and	O
other	O
applications	O
.	O
</s>
<s>
A	O
technology	O
by	O
PrimeSense	O
,	O
used	O
in	O
an	O
early	O
version	O
of	O
Microsoft	B-Algorithm
Kinect	I-Algorithm
,	O
used	O
a	O
pattern	O
of	O
projected	O
infrared	O
points	O
to	O
generate	O
a	O
dense	O
3D	O
image	O
.	O
</s>
<s>
(	O
Later	O
on	O
,	O
the	O
Microsoft	B-Algorithm
Kinect	I-Algorithm
switched	O
to	O
using	O
a	O
time-of-flight	B-Device
camera	I-Device
instead	O
of	O
structured	B-General_Concept
light	I-General_Concept
.	O
)	O
</s>
<s>
Intel	B-Algorithm
RealSense	I-Algorithm
camera	O
projects	O
a	O
series	O
of	O
infrared	O
patterns	O
to	O
obtain	O
the	O
3D	O
structure	O
.	O
</s>
