<s>
The	O
Point	B-Language
Cloud	I-Language
Library	I-Language
(	O
PCL	B-Language
)	O
is	O
an	O
open-source	B-Application
library	B-Library
of	O
algorithms	O
for	O
point	B-Algorithm
cloud	I-Algorithm
processing	O
tasks	O
and	O
3D	O
geometry	B-Algorithm
processing	I-Algorithm
,	O
such	O
as	O
occur	O
in	O
three-dimensional	O
computer	B-Application
vision	I-Application
.	O
</s>
<s>
The	O
library	B-Library
contains	O
algorithms	O
for	O
filtering	O
,	O
feature	O
estimation	O
,	O
surface	O
reconstruction	O
,	O
3D	B-Algorithm
registration	I-Algorithm
,	O
model	B-Algorithm
fitting	I-Algorithm
,	O
object	O
recognition	O
,	O
and	O
segmentation	B-Algorithm
.	O
</s>
<s>
Each	O
module	O
is	O
implemented	O
as	O
a	O
smaller	O
library	B-Library
that	O
can	O
be	O
compiled	O
separately	O
(	O
for	O
example	O
,	O
libpcl_filters	O
,	O
libpcl_features	O
,	O
libpcl_surface	O
,	O
...	O
)	O
.	O
</s>
<s>
PCL	B-Language
has	O
its	O
own	O
data	O
format	O
for	O
storing	O
point	B-Algorithm
clouds	I-Algorithm
-	O
PCD	O
(	O
Point	B-Algorithm
Cloud	I-Algorithm
Data	I-Algorithm
)	O
,	O
but	O
also	O
allows	O
datasets	O
to	O
be	O
loaded	O
and	O
saved	O
in	O
many	O
other	O
formats	O
.	O
</s>
<s>
It	O
is	O
written	O
in	O
C++	B-Language
and	O
released	O
under	O
the	O
BSD	B-Operating_System
license	I-Operating_System
.	O
</s>
<s>
These	O
algorithms	O
have	O
been	O
used	O
,	O
for	O
example	O
,	O
for	O
perception	O
in	O
robotics	O
to	O
filter	O
outliers	O
from	O
noisy	O
data	O
,	O
stitch	B-Algorithm
3D	I-Algorithm
point	I-Algorithm
clouds	I-Algorithm
together	I-Algorithm
,	O
segment	O
relevant	O
parts	O
of	O
a	O
scene	O
,	O
extract	O
keypoints	O
and	O
compute	O
descriptors	O
to	O
recognize	O
objects	O
in	O
the	O
world	O
based	O
on	O
their	O
geometric	O
appearance	O
,	O
and	O
create	O
surfaces	O
from	O
point	B-Algorithm
clouds	I-Algorithm
and	O
visualize	O
them	O
.	O
</s>
<s>
PCL	B-Language
requires	O
several	O
third-party	B-General_Concept
libraries	O
to	O
function	O
,	O
which	O
must	O
be	O
installed	O
.	O
</s>
<s>
Most	O
mathematical	O
operations	O
are	O
implemented	O
using	O
the	O
Eigen	B-Language
library	B-Library
.	O
</s>
<s>
The	O
visualization	O
module	O
for	O
3D	O
point	B-Algorithm
clouds	I-Algorithm
is	O
based	O
on	O
VTK	B-Language
.	O
</s>
<s>
Boost	B-Language
is	O
used	O
for	O
shared	O
pointers	O
and	O
the	O
FLANN	O
library	B-Library
for	O
quick	O
k-nearest	O
neighbor	O
search	O
.	O
</s>
<s>
Additional	O
libraries	O
such	O
as	O
Qhull	O
,	O
OpenNI	B-Application
,	O
or	O
Qt	B-Language
are	O
optional	O
and	O
extend	O
PCL	B-Language
with	O
additional	O
features	O
.	O
</s>
<s>
PCL	B-Language
is	O
cross-platform	B-Operating_System
software	I-Operating_System
that	O
runs	O
on	O
the	O
most	O
commonly	O
used	O
operating	B-General_Concept
systems	I-General_Concept
:	O
Linux	B-Application
,	O
Windows	B-Application
,	O
macOS	B-Application
and	O
Android	B-Application
.	O
</s>
<s>
The	O
library	B-Library
is	O
fully	O
integrated	O
with	O
the	O
Robot	B-Application
Operating	I-Application
System	I-Application
(	O
ROS	B-Application
)	O
and	O
provides	O
support	O
for	O
OpenMP	B-Application
and	O
Intel	B-Application
Threading	I-Application
Building	I-Application
Blocks	I-Application
(	O
TBB	O
)	O
libraries	O
for	O
multi-core	O
parallelism	B-Operating_System
.	O
</s>
<s>
The	O
library	B-Library
is	O
constantly	O
updated	O
and	O
expanded	O
,	O
and	O
its	O
use	O
in	O
various	O
industries	O
is	O
constantly	O
growing	O
.	O
</s>
<s>
For	O
example	O
,	O
PCL	B-Language
participated	O
in	O
the	O
Google	B-Application
Summer	I-Application
of	I-Application
Code	I-Application
2020	O
initiative	O
with	O
three	O
projects	O
.	O
</s>
<s>
One	O
was	O
the	O
extension	O
of	O
PCL	B-Language
for	O
use	O
with	O
Python	B-Language
using	O
Pybind11	O
.	O
</s>
<s>
A	O
large	O
number	O
of	O
examples	O
and	O
tutorials	O
are	O
available	O
on	O
the	O
PCL	B-Language
website	O
,	O
either	O
as	O
C++	B-Language
source	O
files	O
or	O
as	O
tutorials	O
with	O
a	O
detailed	O
description	O
and	O
explanation	O
of	O
the	O
individual	O
steps	O
.	O
</s>
<s>
Point	B-Language
cloud	I-Language
library	I-Language
is	O
widely	O
used	O
in	O
many	O
different	O
fields	O
,	O
here	O
are	O
some	O
examples	O
:	O
</s>
<s>
PCL	B-Language
requires	O
for	O
its	O
installation	O
several	O
third-party	B-General_Concept
libraries	O
,	O
which	O
are	O
listed	O
below	O
.	O
</s>
<s>
Some	O
libraries	O
are	O
optional	O
and	O
extend	O
PCL	B-Language
with	O
additional	O
features	O
.	O
</s>
<s>
The	O
PCL	B-Language
library	B-Library
is	O
built	O
with	O
the	O
CMake	B-Language
build	O
system	O
(	O
)	O
at	O
least	O
in	O
version	O
3.5.0	O
.	O
</s>
<s>
Boost	B-Language
(	O
)	O
at	O
least	O
version	O
1.46.1	O
.	O
</s>
<s>
This	O
set	O
of	O
C++	B-Language
libraries	O
is	O
used	O
for	O
threading	O
and	O
mainly	O
for	O
shared	O
pointers	O
,	O
so	O
there	O
is	O
no	O
need	O
to	O
re-copy	O
data	O
that	O
is	O
already	O
in	O
the	O
system	O
.	O
</s>
<s>
Eigen	B-Language
(	O
)	O
is	O
required	O
at	O
least	O
in	O
version	O
3.0.0	O
.	O
</s>
<s>
It	O
is	O
an	O
open-source	B-Application
template	O
library	B-Library
for	O
linear	O
algebra	O
(	O
matrices	O
,	O
vectors	O
)	O
.	O
</s>
<s>
Most	O
mathematical	O
operations	O
(	O
SSE	B-General_Concept
optimized	O
)	O
in	O
PCL	B-Language
are	O
implemented	O
with	O
Eigen	B-Language
.	O
</s>
<s>
It	O
is	O
a	O
library	B-Library
that	O
performs	O
a	O
fast	O
approximate	O
nearest	O
neighbor	O
search	O
in	O
high	O
dimensional	O
spaces	O
.	O
</s>
<s>
In	O
PCL	B-Language
,	O
it	O
is	O
especially	O
important	O
in	O
the	O
kdtree	B-Data_Structure
module	O
for	O
fast	O
k-nearest	O
neighbor	O
search	O
operations	O
.	O
</s>
<s>
VTK	B-Language
-	I-Language
Visualization	I-Language
ToolKit	I-Language
(	O
)	O
at	O
least	O
version	O
5.6.1	O
.	O
</s>
<s>
Multi-platform	B-Operating_System
software	O
system	O
for	O
rendering	O
3D	O
point	B-Algorithm
cloud	I-Algorithm
,	O
modeling	O
,	O
image	O
processing	O
,	O
volume	O
rendering	O
.	O
</s>
<s>
Used	O
in	O
visualization	O
module	O
for	O
point	B-Algorithm
cloud	I-Algorithm
rendering	O
and	O
visualization	O
.	O
</s>
<s>
In	O
PCL	B-Language
it	O
is	O
used	O
for	O
convex/concave	O
hull	O
decomposition	O
on	O
the	O
surface	O
.	O
</s>
<s>
OpenNI	B-Application
in	O
version	O
>=	O
1.1.0.25	O
(	O
)	O
provides	O
a	O
single	O
unified	O
interface	O
to	O
depth	O
sensors	O
.	O
</s>
<s>
It	O
is	O
used	O
to	O
retrieve	O
point	B-Algorithm
clouds	I-Algorithm
from	O
devices	O
.	O
</s>
<s>
Qt	B-Language
version	O
>=	O
4.6	O
(	O
)	O
is	O
a	O
cross-platform	B-Operating_System
C++	B-Language
framework	O
used	O
for	O
developing	O
applications	O
with	O
a	O
graphical	O
user	O
interface	O
(	O
GUI	O
)	O
.	O
</s>
<s>
Googletest	B-Language
in	O
version	O
>=	O
1.6.0	O
(	O
)	O
is	O
a	O
C++	B-Language
testing	O
framework	O
.	O
</s>
<s>
In	O
PCL	B-Language
,	O
it	O
is	O
used	O
to	O
build	O
test	O
units	O
.	O
</s>
<s>
The	O
PCD	O
(	O
Point	B-Algorithm
Cloud	I-Algorithm
Data	I-Algorithm
)	O
is	O
a	O
file	O
format	O
for	O
storing	O
3D	O
point	B-Algorithm
cloud	I-Algorithm
data	I-Algorithm
.	O
</s>
<s>
It	O
was	O
created	O
because	O
existing	O
formats	O
did	O
not	O
support	O
some	O
of	O
the	O
features	O
provided	O
by	O
the	O
PCL	B-Language
library	B-Library
.	O
</s>
<s>
PCD	O
is	O
the	O
primary	O
data	O
format	O
in	O
PCL	B-Language
,	O
but	O
the	O
library	B-Library
also	O
offers	O
the	O
ability	O
to	O
save	O
and	O
load	O
data	O
in	O
other	O
formats	O
(	O
such	O
as	O
PLY	O
,	O
IFS	O
,	O
VTK	B-Language
,	O
STL	O
,	O
OBJ	O
,	O
X3D	O
)	O
.	O
</s>
<s>
One	O
of	O
the	O
PCD	O
advantages	O
is	O
the	O
ability	O
to	O
store	O
and	O
process	O
organized	O
point	B-Algorithm
cloud	I-Algorithm
datasets	O
.	O
</s>
<s>
The	O
header	O
has	O
a	O
precisely	O
defined	O
format	O
and	O
contains	O
the	O
necessary	O
information	O
about	O
the	O
point	B-Algorithm
cloud	I-Algorithm
data	I-Algorithm
that	O
are	O
stored	O
in	O
it	O
.	O
</s>
<s>
It	O
also	O
shows	O
a	O
number	O
of	O
points	O
(	O
height*width	O
)	O
in	O
the	O
whole	O
cloud	O
and	O
information	O
about	O
whether	O
the	O
point	B-Algorithm
cloud	I-Algorithm
dataset	O
is	O
organized	O
or	O
unorganized	O
.	O
</s>
<s>
The	O
data	O
type	O
specifies	O
in	O
which	O
format	O
the	O
point	B-Algorithm
cloud	I-Algorithm
data	I-Algorithm
are	O
stored	O
(	O
ASCII	O
or	O
binary	O
)	O
.	O
</s>
<s>
Each	O
point	O
can	O
be	O
stored	O
on	O
a	O
separate	O
line	O
(	O
unorganized	O
point-cloud	B-Algorithm
)	O
or	O
they	O
are	O
stored	O
in	O
an	O
image-like	O
organized	O
structure	O
(	O
organized	O
point-cloud	B-Algorithm
)	O
.	O
</s>
<s>
The	O
development	O
of	O
the	O
Point	B-Language
Cloud	I-Language
Library	I-Language
started	O
in	O
March	O
2010	O
at	O
Willow	O
Garage	O
.	O
</s>
<s>
PCL	B-Language
's	O
first	O
official	O
release	O
(	O
Version	O
1.0	O
)	O
was	O
released	O
two	O
months	O
later	O
in	O
May	O
2011	O
.	O
</s>
<s>
PCL	B-Language
is	O
divided	O
into	O
several	O
smaller	O
code	B-Library
libraries	I-Library
that	O
can	O
be	O
compiled	O
separately	O
.	O
</s>
<s>
When	O
scanning	O
a	O
3D	O
point	B-Algorithm
cloud	I-Algorithm
,	O
errors	O
and	O
various	O
deviations	O
can	O
occur	O
,	O
which	O
causes	O
noise	O
in	O
the	O
data	O
.	O
</s>
<s>
This	O
complicates	O
the	O
estimation	O
of	O
some	O
local	O
point	B-Algorithm
cloud	I-Algorithm
characteristics	O
,	O
such	O
as	O
surface	O
normals	O
.	O
</s>
<s>
The	O
pcl_filters	O
library	B-Library
provides	O
several	O
useful	O
filters	O
for	O
removing	O
outliers	O
and	O
noise	O
and	O
also	O
downsampling	O
the	O
data	O
.	O
</s>
<s>
VoxelGrid	O
filter	O
-	O
creates	O
a	O
grid	O
of	O
voxels	O
in	O
a	O
point	B-Algorithm
cloud	I-Algorithm
.	O
</s>
<s>
This	O
leads	O
to	O
downsampling	O
(	O
reduction	O
of	O
the	O
number	O
of	O
points	O
)	O
in	O
the	O
point	B-Algorithm
cloud	I-Algorithm
data	I-Algorithm
.	O
</s>
<s>
StatisticalOutlierRemoval	O
filter	O
-	O
It	O
removes	O
noise	O
from	O
a	O
point	B-Algorithm
cloud	I-Algorithm
dataset	O
using	O
statistical	O
analysis	O
techniques	O
applied	O
to	O
each	O
point	O
's	O
neighborhood	O
and	O
trim	O
all	O
points	O
whose	O
mean	O
distances	O
are	O
outside	O
a	O
defined	O
interval	O
.	O
</s>
<s>
The	O
pcl_features	O
library	B-Library
contains	O
algorithms	O
and	O
data	O
structures	O
for	O
3D	O
feature	O
estimation	O
.	O
</s>
<s>
Some	O
of	O
other	O
descriptors	O
in	O
the	O
library	B-Library
are	O
Viewpoint	O
Feature	O
Histogram	O
(	O
VFH	O
)	O
descriptor	O
,	O
NARF	O
descriptors	O
,	O
Moment	O
of	O
inertia	O
and	O
eccentricity	O
based	O
descriptors	O
,	O
Globally	O
Aligned	O
Spatial	O
Distribution	O
(	O
GASD	O
)	O
descriptors	O
,	O
and	O
more	O
.	O
</s>
<s>
The	O
pcl_segmentation	O
library	B-Library
contains	O
algorithms	O
for	O
segmenting	O
a	O
point	B-Algorithm
cloud	I-Algorithm
into	O
different	O
clusters	O
.	O
</s>
<s>
There	O
are	O
implemented	O
several	O
classes	O
,	O
that	O
support	O
various	O
segmentation	B-Algorithm
methods	O
:	O
</s>
<s>
The	O
pcl_visualization	O
library	B-Library
is	O
used	O
to	O
quickly	O
and	O
easily	O
visualize	O
3D	O
point	B-Algorithm
cloud	I-Algorithm
data	I-Algorithm
.	O
</s>
<s>
The	O
package	O
makes	O
use	O
of	O
the	O
VTK	B-Language
library	B-Library
for	O
3D	O
rendering	O
of	O
clouds	O
and	O
range	O
images	O
.	O
</s>
<s>
The	O
library	B-Library
offers	O
:	O
</s>
<s>
The	O
CloudViewer	O
class	O
is	O
for	O
a	O
simple	O
point	B-Algorithm
cloud	I-Algorithm
visualization	O
.	O
</s>
<s>
RangeImageVisualizer	O
can	O
be	O
used	O
to	O
visualize	O
a	O
range	O
image	O
as	O
a	O
3D	O
point	B-Algorithm
cloud	I-Algorithm
or	O
as	O
a	O
picture	O
where	O
the	O
colors	O
correspond	O
to	O
range	O
values	O
.	O
</s>
<s>
It	O
can	O
display	O
both	O
simple	O
point	B-Algorithm
cloud	I-Algorithm
and	O
point	B-Algorithm
cloud	I-Algorithm
that	O
contains	O
colour	O
data	O
.	O
</s>
<s>
Unlike	O
CloudViewer	O
,	O
it	O
can	O
also	O
draw	O
interesting	O
point	B-Algorithm
cloud	I-Algorithm
information	O
such	O
as	O
normals	O
,	O
principal	O
curvatures	O
and	O
geometries	O
.	O
</s>
<s>
It	O
can	O
display	O
multiple	O
point	B-Algorithm
clouds	I-Algorithm
side-by-side	O
so	O
they	O
can	O
be	O
easily	O
compared	O
,	O
or	O
draw	O
various	O
primitive	O
shapes	O
(	O
e.g.	O
,	O
cylinders	O
,	O
spheres	O
,	O
lines	O
,	O
polygons	O
,	O
etc	O
.	O
)	O
</s>
<s>
The	O
registration	B-Algorithm
is	O
the	O
problem	O
of	O
aligning	O
various	O
point	B-Algorithm
cloud	I-Algorithm
datasets	O
acquired	O
from	O
different	O
views	O
into	O
a	O
single	O
point	B-Algorithm
cloud	I-Algorithm
model	O
.	O
</s>
<s>
The	O
pcl_registration	O
library	B-Library
implements	O
number	O
of	O
point	B-Algorithm
cloud	I-Algorithm
registration	I-Algorithm
algorithms	O
for	O
both	O
organized	O
and	O
unorganized	O
datasets	O
.	O
</s>
<s>
Iterative	B-General_Concept
Closest	I-General_Concept
Point	I-General_Concept
algorithm	O
is	O
minimizing	O
the	O
distances	O
between	O
the	O
points	O
of	O
two	O
pointclouds	O
.	O
</s>
<s>
Normal	B-Algorithm
Distributions	I-Algorithm
Transform	I-Algorithm
(	O
NDT	O
)	O
is	O
a	O
registration	B-Algorithm
algorithm	O
that	O
can	O
be	O
used	O
to	O
determine	O
a	O
rigid	O
transformation	O
between	O
two	O
point	B-Algorithm
clouds	I-Algorithm
that	O
have	O
over	O
100,000	O
points	O
.	O
</s>
<s>
The	O
sample_consensus	O
library	B-Library
holds	O
SAmple	O
Consensus	O
(	O
SAC	O
)	O
methods	O
like	O
RANSAC	B-Algorithm
and	O
models	O
to	O
detect	O
specific	O
objects	O
in	O
point	B-Algorithm
clouds	I-Algorithm
.	O
</s>
<s>
Some	O
of	O
the	O
models	O
implemented	O
in	O
this	O
library	B-Library
include	O
plane	O
models	O
that	O
are	O
often	O
used	O
to	O
detect	O
interior	O
surfaces	O
such	O
as	O
walls	O
and	O
floors	O
.	O
</s>
<s>
Robust	O
sample	O
consensus	O
estimators	O
that	O
are	O
available	O
in	O
the	O
library	B-Library
:	O
</s>
<s>
Several	O
algorithms	O
for	O
surface	O
reconstruction	O
of	O
3D	O
point	B-Algorithm
clouds	I-Algorithm
are	O
implemented	O
in	O
the	O
pcl_surface	O
library	B-Library
.	O
</s>
<s>
One	O
of	O
the	O
most	O
commonly	O
used	O
is	O
meshing	O
,	O
and	O
the	O
PCL	B-Language
library	B-Library
has	O
two	O
algorithms	O
:	O
very	O
fast	O
triangulation	O
of	O
original	O
points	O
and	O
slower	O
networking	O
,	O
which	O
also	O
smooths	O
and	O
fills	O
holes	O
.	O
</s>
<s>
The	O
Moving	B-Algorithm
Least	I-Algorithm
Squares	I-Algorithm
(	O
MLS	O
)	O
surface	O
reconstruction	O
method	O
is	O
a	O
resampling	O
algorithm	O
that	O
can	O
reconstruct	O
missing	O
parts	O
of	O
a	O
surface	O
.	O
</s>
<s>
Greedy	B-Algorithm
Projection	I-Algorithm
Triangulation	I-Algorithm
implements	O
an	O
algorithm	O
for	O
fast	O
surface	O
triangulation	O
on	O
an	O
unordered	O
PointCloud	O
with	O
normals	O
.	O
</s>
<s>
The	O
library	B-Library
also	O
implements	O
functions	O
for	O
creating	O
a	O
concave	O
or	O
convex	O
hull	O
polygon	O
for	O
a	O
plane	O
model	O
,	O
Grid	O
projection	O
surface	O
reconstruction	O
algorithm	O
,	O
marching	B-Algorithm
cubes	I-Algorithm
,	O
ear	B-Algorithm
clipping	I-Algorithm
triangulation	O
algorithm	O
,	O
Poisson	O
surface	O
reconstruction	O
algorithm	O
,	O
etc	O
.	O
</s>
<s>
The	O
io_library	O
allows	O
you	O
to	O
load	O
and	O
save	O
point	B-Algorithm
clouds	I-Algorithm
to	O
files	O
,	O
as	O
well	O
as	O
capture	O
clouds	O
from	O
various	O
devices	O
.	O
</s>
<s>
It	O
includes	O
functions	O
that	O
allow	O
you	O
to	O
concatenate	O
the	O
points	O
of	O
two	O
different	O
point	B-Algorithm
clouds	I-Algorithm
with	O
the	O
same	O
type	O
and	O
number	O
of	O
fields	O
.	O
</s>
<s>
The	O
library	B-Library
can	O
also	O
concatenate	O
fields	O
(	O
e.g.	O
,	O
dimensions	O
)	O
of	O
two	O
different	O
point	B-Algorithm
clouds	I-Algorithm
with	O
same	O
number	O
of	O
points	O
.	O
</s>
<s>
Starting	O
with	O
PCL	B-Language
1.0	O
the	O
library	B-Library
offers	O
a	O
new	O
generic	O
grabber	O
interface	O
that	O
provides	O
easy	O
access	O
to	O
different	O
devices	O
and	O
file	O
formats	O
.	O
</s>
<s>
The	O
first	O
devices	O
supported	O
for	O
data	O
collection	O
were	O
OpenNI	B-Application
compatible	O
cameras	O
(	O
tested	O
with	O
Primesense	O
Reference	O
Design	O
,	O
Microsoft	O
Kinect	O
and	O
Asus	O
Xtion	O
Pro	O
cameras	O
)	O
.	O
</s>
<s>
As	O
of	O
PCL	B-Language
1.7	O
,	O
point	B-Algorithm
cloud	I-Algorithm
data	I-Algorithm
can	O
be	O
also	O
obtained	O
from	O
the	O
Velodyne	O
High	O
Definition	O
LiDAR	O
(	O
HDL	O
)	O
system	O
,	O
which	O
produces	O
360	O
degree	O
point	B-Algorithm
clouds	I-Algorithm
.	O
</s>
<s>
PCL	B-Language
supports	O
both	O
the	O
original	O
HDL-64e	O
and	O
HDL-32e	O
.	O
</s>
<s>
PCL	B-Language
1.8	O
brings	O
support	O
for	O
IDS-Imaging	O
cameras	O
,	O
DepthSense	B-General_Concept
cameras	O
(	O
e.g.	O
</s>
<s>
Creative	O
Senz3D	O
,	O
DepthSense	B-General_Concept
DS325	O
)	O
,	O
and	O
scanners	O
.	O
</s>
<s>
The	O
pcl_kdtree	O
library	B-Library
provides	O
the	O
kd-tree	B-Data_Structure
data-structure	O
for	O
organizing	O
a	O
set	O
of	O
points	O
in	O
a	O
space	O
with	O
k	O
dimensions	O
.	O
</s>
<s>
The	O
pcl_octree	O
library	B-Library
implements	O
the	O
octree	B-Data_Structure
hierarchical	O
tree	O
data	O
structure	O
for	O
point	B-Algorithm
cloud	I-Algorithm
data	I-Algorithm
.	O
</s>
<s>
The	O
library	B-Library
provides	O
nearest	O
neighbor	O
search	O
algorithms	O
,	O
such	O
as	O
“	O
Neighbors	O
within	O
Voxel	O
Search	O
”	O
,	O
“	O
K	O
Nearest	O
Neighbor	O
Search	O
”	O
and	O
“	O
Neighbors	O
within	O
Radius	O
Search	O
”	O
.	O
</s>
<s>
There	O
are	O
also	O
several	O
octree	B-Data_Structure
types	O
that	O
differ	O
by	O
their	O
leaf	O
node	O
's	O
properties	O
.	O
</s>
<s>
The	O
library	B-Library
can	O
be	O
also	O
used	O
for	O
detection	O
of	O
spatial	O
changes	O
between	O
multiple	O
unorganized	O
point	B-Algorithm
clouds	I-Algorithm
by	O
recursive	O
comparison	O
of	O
octet	O
tree	O
structures	O
.	O
</s>
<s>
The	O
pcl_search	O
library	B-Library
implements	O
methods	O
for	O
searching	O
for	O
nearest	O
neighbors	O
using	O
different	O
data	O
structures	O
,	O
that	O
can	O
be	O
found	O
in	O
other	O
modules	O
,	O
such	O
as	O
KdTree	B-Data_Structure
,	O
Octree	B-Data_Structure
,	O
or	O
specialized	O
search	O
for	O
organized	O
datasets	O
.	O
</s>
<s>
The	O
range_image	O
library	B-Library
contains	O
two	O
classes	O
for	O
representing	O
and	O
working	O
with	O
range	O
images	O
whose	O
pixel	O
values	O
represent	O
a	O
distance	O
from	O
the	O
sensor	O
.	O
</s>
<s>
The	O
range	O
image	O
can	O
be	O
converted	O
to	O
a	O
point	B-Algorithm
cloud	I-Algorithm
if	O
the	O
sensor	O
position	O
is	O
specified	O
or	O
the	O
borders	O
can	O
be	O
extracted	O
from	O
it	O
.	O
</s>
<s>
The	O
pcl_keypoints	O
library	B-Library
contains	O
implementations	O
of	O
point	B-Algorithm
cloud	I-Algorithm
keypoint	O
detection	O
algorithms	O
(	O
AGAST	O
corner	O
point	O
detector	O
,	O
Harris	B-General_Concept
detector	I-General_Concept
,	O
BRISK	O
detector	O
,	O
etc	O
.	O
</s>
<s>
The	O
pcl_common	O
library	B-Library
contains	O
the	O
core	O
data	O
structures	O
for	O
point	B-Algorithm
cloud	I-Algorithm
,	O
types	O
for	O
point	O
representation	O
,	O
surface	O
normals	O
,	O
RGB	O
color	O
values	O
,	O
etc	O
.	O
</s>
<s>
The	O
common	O
library	B-Library
is	O
mainly	O
used	O
by	O
other	O
PCL	B-Language
modules	O
.	O
</s>
