<s>
A	O
point	B-Algorithm
cloud	I-Algorithm
is	O
a	O
discrete	O
set	O
of	O
data	O
points	O
in	O
space	O
.	O
</s>
<s>
Point	B-Algorithm
clouds	I-Algorithm
are	O
generally	O
produced	O
by	O
3D	B-Algorithm
scanners	I-Algorithm
or	O
by	O
photogrammetry	B-Application
software	O
,	O
which	O
measure	O
many	O
points	O
on	O
the	O
external	O
surfaces	O
of	O
objects	O
around	O
them	O
.	O
</s>
<s>
As	O
the	O
output	O
of	O
3D	B-Algorithm
scanning	I-Algorithm
processes	O
,	O
point	B-Algorithm
clouds	I-Algorithm
are	O
used	O
for	O
many	O
purposes	O
,	O
including	O
to	O
create	O
3D	O
computer-aided	B-Application
design	I-Application
(	O
CAD	B-Application
)	O
models	O
for	O
manufactured	O
parts	O
,	O
for	O
metrology	O
and	O
quality	O
inspection	O
,	O
and	O
for	O
a	O
multitude	O
of	O
visualizing	O
,	O
animating	O
,	O
rendering	O
,	O
and	O
mass	O
customization	O
applications	O
.	O
</s>
<s>
Point	B-Algorithm
clouds	I-Algorithm
are	O
often	O
aligned	O
with	O
3D	O
models	O
or	O
with	O
other	O
point	B-Algorithm
clouds	I-Algorithm
,	O
a	O
process	O
termed	O
point	B-Algorithm
set	I-Algorithm
registration	I-Algorithm
.	O
</s>
<s>
For	O
industrial	O
metrology	O
or	O
inspection	O
using	O
industrial	O
computed	O
tomography	O
,	O
the	O
point	B-Algorithm
cloud	I-Algorithm
of	O
a	O
manufactured	O
part	O
can	O
be	O
aligned	O
to	O
an	O
existing	O
model	O
and	O
compared	O
to	O
check	O
for	O
differences	O
.	O
</s>
<s>
Geometric	B-Application
dimensions	I-Application
and	I-Application
tolerances	I-Application
can	O
also	O
be	O
extracted	O
directly	O
from	O
the	O
point	B-Algorithm
cloud	I-Algorithm
.	O
</s>
<s>
While	O
point	B-Algorithm
clouds	I-Algorithm
can	O
be	O
directly	O
rendered	O
and	O
inspected	O
,	O
point	B-Algorithm
clouds	I-Algorithm
are	O
often	O
converted	O
to	O
polygon	B-Algorithm
mesh	I-Algorithm
or	O
triangle	B-Algorithm
mesh	I-Algorithm
models	O
,	O
non-uniform	B-Algorithm
rational	I-Algorithm
B-spline	I-Algorithm
(	O
NURBS	B-Algorithm
)	O
surface	O
models	O
,	O
or	O
CAD	B-Application
models	I-Application
through	O
a	O
process	O
commonly	O
referred	O
to	O
as	O
surface	O
reconstruction	O
.	O
</s>
<s>
There	O
are	O
many	O
techniques	O
for	O
converting	O
a	O
point	B-Algorithm
cloud	I-Algorithm
to	O
a	O
3D	O
surface	O
.	O
</s>
<s>
Some	O
approaches	O
,	O
like	O
Delaunay	B-Algorithm
triangulation	I-Algorithm
,	O
alpha	O
shapes	O
,	O
and	O
ball	O
pivoting	O
,	O
build	O
a	O
network	O
of	O
triangles	O
over	O
the	O
existing	O
vertices	O
of	O
the	O
point	B-Algorithm
cloud	I-Algorithm
,	O
while	O
other	O
approaches	O
convert	O
the	O
point	B-Algorithm
cloud	I-Algorithm
into	O
a	O
volumetric	B-Algorithm
distance	B-Algorithm
field	I-Algorithm
and	O
reconstruct	O
the	O
implicit	B-Algorithm
surface	I-Algorithm
so	O
defined	O
through	O
a	O
marching	B-Algorithm
cubes	I-Algorithm
algorithm	I-Algorithm
.	O
</s>
<s>
In	O
geographic	B-Application
information	I-Application
systems	I-Application
,	O
point	B-Algorithm
clouds	I-Algorithm
are	O
one	O
of	O
the	O
sources	O
used	O
to	O
make	O
digital	B-Application
elevation	I-Application
model	I-Application
of	O
the	O
terrain	O
.	O
</s>
<s>
Drones	O
are	O
often	O
used	O
to	O
collect	O
a	O
series	O
of	O
RGB	O
images	O
which	O
can	O
be	O
later	O
processed	O
on	O
a	O
computer	O
vision	O
algorithm	O
platform	O
such	O
as	O
on	O
AgiSoft	O
Photoscan	O
,	O
Pix4D	O
or	O
DroneDeploy	O
to	O
create	O
RGB	O
point	B-Algorithm
clouds	I-Algorithm
from	O
where	O
distances	O
and	O
volumetric	B-Algorithm
estimations	O
can	O
be	O
made	O
.	O
</s>
<s>
Point	B-Algorithm
clouds	I-Algorithm
can	O
also	O
be	O
used	O
to	O
represent	O
volumetric	B-Algorithm
data	O
,	O
as	O
is	O
sometimes	O
done	O
in	O
medical	B-Application
imaging	I-Application
.	O
</s>
<s>
Using	O
point	B-Algorithm
clouds	I-Algorithm
,	O
multi-sampling	O
and	O
data	B-General_Concept
compression	I-General_Concept
can	O
be	O
achieved	O
.	O
</s>
<s>
MPEG	O
began	O
standardizing	O
point	B-Algorithm
cloud	I-Algorithm
compression	O
(	O
PCC	O
)	O
with	O
a	O
Call	O
for	O
Proposal	O
(	O
CfP	O
)	O
in	O
2017	O
.	O
</s>
<s>
Three	O
categories	O
of	O
point	B-Algorithm
clouds	I-Algorithm
were	O
identified	O
:	O
category	O
1	O
for	O
static	O
point	B-Algorithm
clouds	I-Algorithm
,	O
category	O
2	O
for	O
dynamic	O
point	B-Algorithm
clouds	I-Algorithm
,	O
and	O
category	O
3	O
for	O
LiDAR	O
sequences	O
(	O
dynamically	O
acquired	O
point	B-Algorithm
clouds	I-Algorithm
)	O
.	O
</s>
