<s>
3D	B-Algorithm
scanning	I-Algorithm
is	O
the	O
process	O
of	O
analyzing	O
a	O
real-world	O
object	O
or	O
environment	O
to	O
collect	O
three	O
dimensional	O
data	O
of	O
its	O
shape	O
and	O
possibly	O
its	O
appearance	O
(	O
e.g.	O
</s>
<s>
A	O
3D	B-Algorithm
scanner	I-Algorithm
can	O
be	O
based	O
on	O
many	O
different	O
technologies	O
,	O
each	O
with	O
its	O
own	O
limitations	O
,	O
advantages	O
and	O
costs	O
.	O
</s>
<s>
For	O
example	O
,	O
industrial	O
computed	O
tomography	O
scanning	O
,	O
structured-light	B-Algorithm
3D	I-Algorithm
scanners	I-Algorithm
,	O
LiDAR	O
and	O
Time	B-Device
Of	I-Device
Flight	I-Device
3D	B-Algorithm
Scanners	I-Algorithm
can	O
be	O
used	O
to	O
construct	O
digital	O
3D	O
models	O
,	O
without	O
destructive	O
testing	O
.	O
</s>
<s>
These	O
devices	O
are	O
used	O
extensively	O
by	O
the	O
entertainment	O
industry	O
in	O
the	O
production	O
of	O
movies	O
and	O
video	O
games	O
,	O
including	O
virtual	B-Application
reality	I-Application
.	O
</s>
<s>
Other	O
common	O
applications	O
of	O
this	O
technology	O
include	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
motion	B-Application
capture	I-Application
,	O
gesture	B-General_Concept
recognition	I-General_Concept
,	O
robotic	O
mapping	O
,	O
industrial	O
design	O
,	O
orthotics	O
and	O
prosthetics	O
,	O
reverse	O
engineering	O
and	O
prototyping	O
,	O
quality	O
control/inspection	O
and	O
the	O
digitization	O
of	O
cultural	O
artifacts	O
.	O
</s>
<s>
The	O
purpose	O
of	O
a	O
3D	B-Algorithm
scanner	I-Algorithm
is	O
usually	O
to	O
create	O
a	O
3D	O
model	O
.	O
</s>
<s>
This	O
3D	O
model	O
consists	O
of	O
a	O
polygon	B-Algorithm
mesh	I-Algorithm
or	O
point	B-Algorithm
cloud	I-Algorithm
of	O
geometric	O
samples	O
on	O
the	O
surface	O
of	O
the	O
subject	O
.	O
</s>
<s>
These	O
points	O
can	O
then	O
be	O
used	O
to	O
extrapolate	O
the	O
shape	O
of	O
the	O
subject	O
(	O
a	O
process	O
called	O
reconstruction	B-Algorithm
)	O
.	O
</s>
<s>
3D	B-Algorithm
scanners	I-Algorithm
share	O
several	O
traits	O
with	O
cameras	O
.	O
</s>
<s>
While	O
a	O
camera	O
collects	O
colour	O
information	O
about	O
surfaces	O
within	O
its	O
field	O
of	O
view	O
,	O
a	O
3D	B-Algorithm
scanner	I-Algorithm
collects	O
distance	O
information	O
about	O
surfaces	O
within	O
its	O
field	O
of	O
view	O
.	O
</s>
<s>
The	O
"	O
picture	O
"	O
produced	O
by	O
a	O
3D	B-Algorithm
scanner	I-Algorithm
describes	O
the	O
distance	O
to	O
a	O
surface	O
at	O
each	O
point	O
in	O
the	O
picture	O
.	O
</s>
<s>
These	O
scans	O
have	O
to	O
be	O
brought	O
into	O
a	O
common	O
reference	O
system	O
,	O
a	O
process	O
that	O
is	O
usually	O
called	O
alignment	O
or	O
registration	B-Algorithm
,	O
and	O
then	O
merged	O
to	O
create	O
a	O
complete	O
3D	O
model	O
.	O
</s>
<s>
This	O
whole	O
process	O
,	O
going	O
from	O
the	O
single	O
range	O
map	O
to	O
the	O
whole	O
model	O
,	O
is	O
usually	O
known	O
as	O
the	O
3D	B-Algorithm
scanning	I-Algorithm
pipeline	O
.	O
</s>
<s>
Contact	O
3D	B-Algorithm
scanners	I-Algorithm
work	O
by	O
physically	O
probing	O
(	O
touching	O
)	O
the	O
part	O
and	O
recording	O
the	O
position	O
of	O
the	O
sensor	O
as	O
the	O
probe	O
moves	O
around	O
the	O
part	O
.	O
</s>
<s>
There	O
are	O
two	O
main	O
types	O
of	O
contact	O
3D	B-Algorithm
scanners	I-Algorithm
:	O
</s>
<s>
This	O
is	O
referred	O
to	O
as	O
a	O
time-of-flight	B-Device
camera	I-Device
.	O
</s>
<s>
Triangulation	B-Algorithm
based	O
3D	O
laser	O
scanners	O
are	O
also	O
active	O
scanners	O
that	O
use	O
laser	O
light	O
to	O
probe	O
the	O
environment	O
.	O
</s>
<s>
With	O
respect	O
to	O
time-of-flight	O
3D	O
laser	O
scanner	O
the	O
triangulation	B-Algorithm
laser	O
shines	O
a	O
laser	O
on	O
the	O
subject	O
and	O
exploits	O
a	O
camera	O
to	O
look	O
for	O
the	O
location	O
of	O
the	O
laser	O
dot	O
.	O
</s>
<s>
This	O
technique	O
is	O
called	O
triangulation	B-Algorithm
because	O
the	O
laser	O
dot	O
,	O
the	O
camera	O
and	O
the	O
laser	O
emitter	O
form	O
a	O
triangle	O
.	O
</s>
<s>
The	O
National	O
Research	O
Council	O
of	O
Canada	O
was	O
among	O
the	O
first	O
institutes	O
to	O
develop	O
the	O
triangulation	B-Algorithm
based	O
laser	O
scanning	O
technology	O
in	O
1978	O
.	O
</s>
<s>
Time-of-flight	O
and	O
triangulation	B-Algorithm
range	O
finders	O
each	O
have	O
strengths	O
and	O
weaknesses	O
that	O
make	O
them	O
suitable	O
for	O
different	O
situations	O
.	O
</s>
<s>
Triangulation	B-Algorithm
range	O
finders	O
are	O
exactly	O
the	O
opposite	O
.	O
</s>
<s>
The	O
accuracy	O
of	O
triangulation	B-Algorithm
range	O
finders	O
is	O
on	O
the	O
order	O
of	O
tens	O
of	O
micrometers	O
.	O
</s>
<s>
Hand-held	O
laser	O
scanners	O
create	O
a	O
3D	O
image	O
through	O
the	O
triangulation	B-Algorithm
mechanism	O
described	O
above	O
:	O
a	O
laser	O
dot	O
or	O
line	O
is	O
projected	O
onto	O
an	O
object	O
from	O
a	O
hand-held	O
device	O
and	O
a	O
sensor	O
(	O
typically	O
a	O
charge-coupled	B-Algorithm
device	I-Algorithm
or	O
position	O
sensitive	O
device	O
)	O
measures	O
the	O
distance	O
to	O
the	O
surface	O
.	O
</s>
<s>
External	O
tracking	O
often	O
takes	O
the	O
form	O
of	O
a	O
laser	O
tracker	O
(	O
to	O
provide	O
the	O
sensor	O
position	O
)	O
with	O
integrated	O
camera	O
(	O
to	O
determine	O
the	O
orientation	O
of	O
the	O
scanner	O
)	O
or	O
a	O
photogrammetric	B-Application
solution	O
using	O
3	O
or	O
more	O
cameras	O
providing	O
the	O
complete	O
six	O
degrees	O
of	O
freedom	O
of	O
the	O
scanner	O
.	O
</s>
<s>
Data	O
is	O
collected	O
by	O
a	O
computer	O
and	O
recorded	O
as	O
data	O
points	O
within	O
three-dimensional	O
space	O
,	O
with	O
processing	O
this	O
can	O
be	O
converted	O
into	O
a	O
triangulated	O
mesh	B-Algorithm
and	O
then	O
a	O
computer-aided	B-Application
design	I-Application
model	O
,	O
often	O
as	O
non-uniform	B-Algorithm
rational	I-Algorithm
B-spline	I-Algorithm
surfaces	O
.	O
</s>
<s>
Structured-light	B-Algorithm
3D	I-Algorithm
scanners	I-Algorithm
project	O
a	O
pattern	O
of	O
light	O
on	O
the	O
subject	O
and	O
look	O
at	O
the	O
deformation	O
of	O
the	O
pattern	O
on	O
the	O
subject	O
.	O
</s>
<s>
The	O
pattern	O
is	O
projected	O
onto	O
the	O
subject	O
using	O
either	O
an	O
LCD	B-Device
projector	I-Device
or	O
other	O
stable	O
light	O
source	O
.	O
</s>
<s>
Perfect	O
maps	O
have	O
also	O
been	O
proven	O
useful	O
as	O
structured	O
light	O
patterns	O
that	O
solve	O
the	O
correspondence	B-Algorithm
problem	I-Algorithm
and	O
allow	O
for	O
error	O
detection	O
and	O
error	O
correction	O
.	O
</s>
<s>
The	O
advantage	O
of	O
structured-light	B-Algorithm
3D	I-Algorithm
scanners	I-Algorithm
is	O
speed	O
and	O
precision	O
.	O
</s>
<s>
A	O
real-time	O
scanner	O
using	O
digital	O
fringe	B-Algorithm
projection	I-Algorithm
and	O
phase-shifting	O
technique	O
(	O
certain	O
kinds	O
of	O
structured	O
light	O
methods	O
)	O
was	O
developed	O
,	O
to	O
capture	O
,	O
reconstruct	O
,	O
and	O
render	O
high-density	O
details	O
of	O
dynamically	O
deformable	O
objects	O
(	O
such	O
as	O
facial	O
expressions	O
)	O
at	O
40	O
frames	O
per	O
second	O
.	O
</s>
<s>
Modulated	O
light	O
3D	B-Algorithm
scanners	I-Algorithm
shine	O
a	O
continually	O
changing	O
light	O
at	O
the	O
subject	O
.	O
</s>
<s>
These	O
techniques	O
produce	O
a	O
discrete	B-Algorithm
3D	I-Algorithm
volumetric	I-Algorithm
representation	I-Algorithm
that	O
can	O
be	O
directly	O
visualised	O
,	O
manipulated	O
or	O
converted	O
to	O
traditional	O
3D	O
surface	O
by	O
mean	O
of	O
isosurface	B-Algorithm
extraction	I-Algorithm
algorithms	I-Algorithm
.	O
</s>
<s>
Although	O
most	O
common	O
in	O
medicine	O
,	O
industrial	O
computed	O
tomography	O
,	O
microtomography	O
and	O
MRI	B-Algorithm
are	O
also	O
used	O
in	O
other	O
fields	O
for	O
acquiring	O
a	O
digital	O
representation	O
of	O
an	O
object	O
and	O
its	O
interior	O
,	O
such	O
as	O
non	O
destructive	O
materials	O
testing	O
,	O
reverse	O
engineering	O
,	O
or	O
studying	O
biological	O
and	O
paleontological	O
specimens	O
.	O
</s>
<s>
Passive	O
3D	B-Algorithm
imaging	I-Algorithm
solutions	O
do	O
not	O
emit	O
any	O
kind	O
of	O
radiation	O
themselves	O
,	O
but	O
instead	O
rely	O
on	O
detecting	O
reflected	O
ambient	O
radiation	O
.	O
</s>
<s>
This	O
method	O
is	O
based	O
on	O
the	O
same	O
principles	O
driving	O
human	O
stereoscopic	B-Algorithm
vision	I-Algorithm
.	O
</s>
<s>
Photometric	B-Algorithm
systems	O
usually	O
use	O
a	O
single	O
camera	O
,	O
but	O
take	O
multiple	O
images	O
under	O
varying	O
lighting	O
conditions	O
.	O
</s>
<s>
These	O
silhouettes	O
are	O
extruded	O
and	O
intersected	O
to	O
form	O
the	O
visual	B-Algorithm
hull	I-Algorithm
approximation	O
of	O
the	O
object	O
.	O
</s>
<s>
Photogrammetry	B-Application
provides	O
reliable	O
information	O
about	O
3D	O
shapes	O
of	O
physical	O
objects	O
based	O
on	O
analysis	O
of	O
photographic	O
images	O
.	O
</s>
<s>
The	O
resulting	O
3D	O
data	O
is	O
typically	O
provided	O
as	O
a	O
3D	O
point	B-Algorithm
cloud	I-Algorithm
,	O
3D	B-Algorithm
mesh	I-Algorithm
or	O
3D	O
points	O
.	O
</s>
<s>
Modern	O
photogrammetry	B-Application
software	O
applications	O
automatically	O
analyze	O
a	O
large	O
number	O
of	O
digital	O
images	O
for	O
3D	B-Algorithm
reconstruction	I-Algorithm
,	O
however	O
manual	O
interaction	O
may	O
be	O
required	O
if	O
the	O
software	O
cannot	O
automatically	O
determine	O
the	O
3D	O
positions	O
of	O
the	O
camera	O
in	O
the	O
images	O
which	O
is	O
an	O
essential	O
step	O
in	O
the	O
reconstruction	B-Algorithm
pipeline	O
.	O
</s>
<s>
Various	O
software	O
packages	O
are	O
available	O
including	O
PhotoModeler	O
,	O
Geodetic	O
Systems	O
,	O
Autodesk	B-Application
ReCap	I-Application
,	O
RealityCapture	O
and	O
Agisoft	O
Metashape	O
(	O
see	O
comparison	O
of	O
photogrammetry	B-Application
software	O
)	O
.	O
</s>
<s>
Close	O
range	O
photogrammetry	B-Application
typically	O
uses	O
a	O
handheld	O
camera	O
such	O
as	O
a	O
DSLR	B-Device
with	O
a	O
fixed	O
focal	O
length	O
lens	O
to	O
capture	O
images	O
of	O
objects	O
for	O
3D	B-Algorithm
reconstruction	I-Algorithm
.	O
</s>
<s>
Subjects	O
include	O
smaller	O
objects	O
such	O
as	O
a	O
building	B-Application
facade	I-Application
,	O
vehicles	O
,	O
sculptures	O
,	O
rocks	O
,	O
and	O
shoes	O
.	O
</s>
<s>
Camera	O
Arrays	O
can	O
be	O
used	O
to	O
generate	O
3D	O
point	B-Algorithm
clouds	I-Algorithm
or	O
meshes	B-Algorithm
of	O
live	O
objects	O
such	O
as	O
people	O
or	O
pets	O
by	O
synchronizing	O
multiple	O
cameras	O
to	O
photograph	O
a	O
subject	O
from	O
multiple	O
perspectives	O
at	O
the	O
same	O
time	O
for	O
3D	B-Algorithm
object	I-Algorithm
reconstruction	I-Algorithm
.	O
</s>
<s>
Wide	O
angle	O
photogrammetry	B-Application
can	O
be	O
used	O
to	O
capture	O
the	O
interior	O
of	O
buildings	O
or	O
enclosed	O
spaces	O
using	O
a	O
wide	O
angle	O
lens	O
camera	O
such	O
as	O
a	O
360	B-Algorithm
camera	I-Algorithm
.	O
</s>
<s>
Aerial	O
photogrammetry	B-Application
uses	O
aerial	O
images	O
acquired	O
by	O
satellite	O
,	O
commercial	O
aircraft	O
or	O
UAV	O
drone	O
to	O
collect	O
images	O
of	O
buildings	O
,	O
structures	O
and	O
terrain	O
for	O
3D	B-Algorithm
reconstruction	I-Algorithm
into	O
a	O
point	B-Algorithm
cloud	I-Algorithm
or	O
mesh	B-Algorithm
.	O
</s>
<s>
Further	O
processing	O
such	O
as	O
expressing	O
building	O
footprints	O
as	O
polygons	O
is	O
used	O
for	O
data	O
storing	O
in	O
GIS	B-Application
databases	O
.	O
</s>
<s>
This	O
approach	O
involves	O
registering	O
and	O
merging	O
the	O
detailed	O
facade	B-Application
models	O
with	O
a	O
complementary	O
airborne	O
model	O
.	O
</s>
<s>
Ground-based	O
modeling	O
process	O
results	O
in	O
a	O
detailed	O
model	O
of	O
the	O
building	O
facades	B-Application
.	O
</s>
<s>
Using	O
the	O
DSM	O
obtained	O
from	O
airborne	O
laser	O
scans	O
,	O
they	O
localize	O
the	O
acquisition	O
vehicle	O
and	O
register	O
the	O
ground-based	O
facades	B-Application
to	O
the	O
airborne	O
model	O
by	O
means	O
of	O
Monte	O
Carlo	O
localization	O
(	O
MCL	O
)	O
.	O
</s>
<s>
The	O
ground	O
plans	O
of	O
buildings	O
had	O
already	O
been	O
acquired	O
either	O
in	O
analog	O
form	O
by	O
maps	O
and	O
plans	O
or	O
digitally	O
in	O
a	O
2D	O
GIS	B-Application
.	O
</s>
<s>
Afterwards	O
virtual	B-Application
reality	I-Application
city	O
models	O
are	O
generated	O
in	O
the	O
project	O
by	O
texture	O
processing	O
,	O
e.g.	O
</s>
<s>
The	O
project	O
demonstrated	O
the	O
feasibility	O
of	O
rapid	O
acquisition	O
of	O
3D	O
urban	O
GIS	B-Application
.	O
</s>
<s>
Ground	O
plans	O
proved	O
are	O
another	O
very	O
important	O
source	O
of	O
information	O
for	O
3D	O
building	O
reconstruction	B-Algorithm
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
ground	O
plans	O
,	O
can	O
considerably	O
reduce	O
costs	O
in	O
a	O
reconstruction	B-Algorithm
project	O
.	O
</s>
<s>
An	O
example	O
of	O
existing	O
ground	O
plan	O
data	O
usable	O
in	O
building	O
reconstruction	B-Algorithm
is	O
the	O
Digital	B-Application
Cadastral	I-Application
map	I-Application
,	O
which	O
provides	O
information	O
on	O
the	O
distribution	O
of	O
property	O
,	O
including	O
the	O
borders	O
of	O
all	O
agricultural	O
areas	O
and	O
the	O
ground	O
plans	O
of	O
existing	O
buildings	O
.	O
</s>
<s>
At	O
the	O
moment	O
the	O
Digital	B-Application
Cadastral	I-Application
map	I-Application
is	O
built	O
up	O
as	O
a	O
database	O
covering	O
an	O
area	O
,	O
mainly	O
composed	O
by	O
digitizing	O
preexisting	O
maps	O
or	O
plans	O
.	O
</s>
<s>
Systems	O
using	O
regular	O
still	O
cameras	O
mounted	O
on	O
RC	O
helicopters	O
(	O
Photogrammetry	B-Application
)	O
are	O
also	O
possible	O
,	O
and	O
cost	O
around	O
€	O
25,000	O
.	O
</s>
<s>
Note	O
that	O
Google	B-Application
Earth	I-Application
images	O
are	O
too	O
low	O
in	O
resolution	O
to	O
make	O
an	O
accurate	O
3D	O
model	O
.	O
</s>
<s>
The	O
point	B-Algorithm
clouds	I-Algorithm
produced	O
by	O
3D	B-Algorithm
scanners	I-Algorithm
and	O
3D	B-Algorithm
imaging	I-Algorithm
can	O
be	O
used	O
directly	O
for	O
measurement	O
and	O
visualisation	O
in	O
the	O
architecture	O
and	O
construction	O
world	O
.	O
</s>
<s>
Most	O
applications	O
,	O
however	O
,	O
use	O
instead	O
polygonal	O
3D	O
models	O
,	O
NURBS	B-Algorithm
surface	I-Algorithm
models	O
,	O
or	O
editable	O
feature-based	O
CAD	B-Application
models	I-Application
(	O
aka	O
solid	O
models	O
)	O
.	O
</s>
<s>
Polygon	B-Algorithm
mesh	I-Algorithm
models	O
:	O
In	O
a	O
polygonal	O
representation	O
of	O
a	O
shape	O
,	O
a	O
curved	O
surface	O
is	O
modeled	O
as	O
many	O
small	O
faceted	O
flat	O
surfaces	O
(	O
think	O
of	O
a	O
sphere	O
modeled	O
as	O
a	O
disco	O
ball	O
)	O
.	O
</s>
<s>
Polygon	O
models	O
—	O
also	O
called	O
Mesh	B-Algorithm
models	O
,	O
are	O
useful	O
for	O
visualisation	O
,	O
for	O
some	O
CAM	O
(	O
i.e.	O
,	O
machining	O
)	O
,	O
but	O
are	O
generally	O
"	O
heavy	O
"	O
(	O
i.e.	O
,	O
very	O
large	O
data	O
sets	O
)	O
,	O
and	O
are	O
relatively	O
un-editable	O
in	O
this	O
form	O
.	O
</s>
<s>
Reconstruction	B-Algorithm
to	O
polygonal	O
model	O
involves	O
finding	O
and	O
connecting	O
adjacent	O
points	O
with	O
straight	O
lines	O
in	O
order	O
to	O
create	O
a	O
continuous	O
surface	O
.	O
</s>
<s>
GigaMesh	B-Language
,	O
MeshLab	B-Language
,	O
PointCab	O
,	O
kubit	O
PointCloud	O
for	O
AutoCAD	B-Algorithm
,	O
,	O
imagemodel	O
,	O
PolyWorks	O
,	O
Rapidform	O
,	O
Geomagic	B-Application
,	O
Imageware	O
,	O
Rhino	B-Algorithm
3D	I-Algorithm
etc	O
.	O
</s>
<s>
These	O
might	O
be	O
NURBS	B-Algorithm
,	O
TSplines	O
or	O
other	O
curved	O
representations	O
of	O
curved	O
topology	O
.	O
</s>
<s>
Using	O
NURBS	B-Algorithm
,	O
the	O
spherical	O
shape	O
becomes	O
a	O
true	O
mathematical	O
sphere	O
.	O
</s>
<s>
These	O
patches	O
have	O
the	O
advantage	O
of	O
being	O
lighter	O
and	O
more	O
manipulable	O
when	O
exported	O
to	O
CAD	B-Application
.	O
</s>
<s>
Providers	O
of	O
surface	O
modellers	O
include	O
Rapidform	O
,	O
Geomagic	B-Application
,	O
Rhino	B-Algorithm
3D	I-Algorithm
,	O
Maya	O
,	O
T	O
Splines	O
etc	O
.	O
</s>
<s>
Solid	O
CAD	B-Application
models	I-Application
:	O
From	O
an	O
engineering/manufacturing	O
perspective	O
,	O
the	O
ultimate	O
representation	O
of	O
a	O
digitised	O
shape	O
is	O
the	O
editable	O
,	O
parametric	O
CAD	B-Application
model	I-Application
.	O
</s>
<s>
In	O
CAD	B-Application
,	O
the	O
sphere	O
is	O
described	O
by	O
parametric	O
features	O
which	O
are	O
easily	O
edited	O
by	O
changing	O
a	O
value	O
(	O
e.g.	O
,	O
centre	O
point	O
and	O
radius	O
)	O
.	O
</s>
<s>
These	O
CAD	B-Application
models	I-Application
describe	O
not	O
simply	O
the	O
envelope	O
or	O
shape	O
of	O
the	O
object	O
,	O
but	O
CAD	B-Application
models	I-Application
also	O
embody	O
the	O
"	O
design	O
intent	O
"	O
(	O
i.e.	O
,	O
critical	O
features	O
and	O
their	O
relationship	O
to	O
other	O
features	O
)	O
.	O
</s>
<s>
This	O
knowledge	O
would	O
drive	O
the	O
sequence	O
and	O
method	O
of	O
creating	O
the	O
CAD	B-Application
model	I-Application
;	O
a	O
designer	O
with	O
an	O
awareness	O
of	O
this	O
relationship	O
would	O
not	O
design	O
the	O
lug	O
bolts	O
referenced	O
to	O
the	O
outside	O
diameter	O
,	O
but	O
instead	O
,	O
to	O
the	O
center	O
.	O
</s>
<s>
A	O
modeler	O
creating	O
a	O
CAD	B-Application
model	I-Application
will	O
want	O
to	O
include	O
both	O
Shape	O
and	O
design	O
intent	O
in	O
the	O
complete	O
CAD	B-Application
model	I-Application
.	O
</s>
<s>
Vendors	O
offer	O
different	O
approaches	O
to	O
getting	O
to	O
the	O
parametric	O
CAD	B-Application
model	I-Application
.	O
</s>
<s>
Some	O
export	O
the	O
NURBS	B-Algorithm
surfaces	I-Algorithm
and	O
leave	O
it	O
to	O
the	O
CAD	B-Application
designer	O
to	O
complete	O
the	O
model	O
in	O
CAD	B-Application
(	O
e.g.	O
,	O
Geomagic	B-Application
,	O
Imageware	O
,	O
Rhino	B-Algorithm
3D	I-Algorithm
)	O
.	O
</s>
<s>
Others	O
use	O
the	O
scan	O
data	O
to	O
create	O
an	O
editable	O
and	O
verifiable	O
feature	O
based	O
model	O
that	O
is	O
imported	O
into	O
CAD	B-Application
with	O
full	O
feature	O
tree	O
intact	O
,	O
yielding	O
a	O
complete	O
,	O
native	O
CAD	B-Application
model	I-Application
,	O
capturing	O
both	O
shape	O
and	O
design	O
intent	O
(	O
e.g.	O
</s>
<s>
Geomagic	B-Application
,	O
Rapidform	O
)	O
.	O
</s>
<s>
For	O
instance	O
,	O
the	O
market	O
offers	O
various	O
plug-ins	O
for	O
established	O
CAD-programs	O
,	O
such	O
as	O
SolidWorks	B-Application
.	O
</s>
<s>
Xtract3D	O
,	O
DezignWorks	O
and	O
Geomagic	B-Application
for	O
SolidWorks	B-Application
allow	O
manipulating	O
a	O
3D	B-Algorithm
scan	I-Algorithm
directly	O
inside	O
SolidWorks	B-Application
.	O
</s>
<s>
Still	O
other	O
CAD	B-Application
applications	O
are	O
robust	O
enough	O
to	O
manipulate	O
limited	O
points	O
or	O
polygon	O
models	O
within	O
the	O
CAD	B-Application
environment	O
(	O
e.g.	O
,	O
CATIA	B-Algorithm
,	O
AutoCAD	B-Algorithm
,	O
Revit	B-Application
)	O
.	O
</s>
<s>
CT	O
,	O
industrial	O
CT	O
,	O
MRI	B-Algorithm
,	O
or	O
micro-CT	O
scanners	O
do	O
not	O
produce	O
point	B-Algorithm
clouds	I-Algorithm
but	O
a	O
set	O
of	O
2D	O
slices	O
(	O
each	O
termed	O
a	O
"	O
tomogram	O
"	O
)	O
which	O
are	O
then	O
'	O
stacked	O
together	O
 '	O
to	O
produce	O
a	O
3D	O
representation	O
.	O
</s>
<s>
Image	B-Algorithm
segmentation	I-Algorithm
:	O
Where	O
different	O
structures	O
have	O
similar	O
threshold/greyscale	O
values	O
,	O
it	O
can	O
become	O
impossible	O
to	O
separate	O
them	O
simply	O
by	O
adjusting	O
volume	O
rendering	O
parameters	O
.	O
</s>
<s>
The	O
solution	O
is	O
called	O
segmentation	B-Algorithm
,	O
a	O
manual	O
or	O
automatic	O
procedure	O
that	O
can	O
remove	O
the	O
unwanted	O
structures	O
from	O
the	O
image	O
.	O
</s>
<s>
Image	B-Algorithm
segmentation	I-Algorithm
software	O
usually	O
allows	O
export	O
of	O
the	O
segmented	O
structures	O
in	O
CAD	B-Application
or	O
STL	O
format	O
for	O
further	O
manipulation	O
.	O
</s>
<s>
Image-based	B-Algorithm
meshing	I-Algorithm
:	O
When	O
using	O
3D	O
image	O
data	O
for	O
computational	O
analysis	O
(	O
e.g.	O
</s>
<s>
CFD	O
and	O
FEA	O
)	O
,	O
simply	O
segmenting	O
the	O
data	O
and	O
meshing	O
from	O
CAD	B-Application
can	O
become	O
time-consuming	O
,	O
and	O
virtually	O
intractable	O
for	O
the	O
complex	O
topologies	O
typical	O
of	O
image	O
data	O
.	O
</s>
<s>
The	O
solution	O
is	O
called	O
image-based	B-Algorithm
meshing	I-Algorithm
,	O
an	O
automated	O
process	O
of	O
generating	O
an	O
accurate	O
and	O
realistic	O
geometrical	O
description	O
of	O
the	O
scan	O
data	O
.	O
</s>
<s>
3D	B-Algorithm
data	I-Algorithm
acquisition	I-Algorithm
and	I-Algorithm
object	I-Algorithm
reconstruction	I-Algorithm
can	O
be	O
performed	O
using	O
stereo	O
image	O
pairs	O
.	O
</s>
<s>
Stereo	O
photogrammetry	B-Application
or	O
photogrammetry	B-Application
based	O
on	O
a	O
block	O
of	O
overlapped	O
images	O
is	O
the	O
primary	O
approach	O
for	O
3D	B-Algorithm
mapping	I-Algorithm
and	O
object	O
reconstruction	B-Algorithm
using	O
2D	O
images	O
.	O
</s>
<s>
Close-range	O
photogrammetry	B-Application
has	O
also	O
matured	O
to	O
the	O
level	O
where	O
cameras	O
or	O
digital	O
cameras	O
can	O
be	O
used	O
to	O
capture	O
the	O
close-look	O
images	O
of	O
objects	O
,	O
e.g.	O
,	O
buildings	O
,	O
and	O
reconstruct	O
them	O
using	O
the	O
very	O
same	O
theory	O
as	O
the	O
aerial	O
photogrammetry	B-Application
.	O
</s>
<s>
An	O
example	O
of	O
software	O
which	O
could	O
do	O
this	O
is	O
Vexcel	B-Application
FotoG	O
5	O
.	O
</s>
<s>
This	O
software	O
has	O
now	O
been	O
replaced	O
by	O
Vexcel	B-Application
GeoSynth	O
.	O
</s>
<s>
Another	O
similar	O
software	O
program	O
is	O
Microsoft	B-Application
Photosynth	I-Application
.	O
</s>
<s>
His	O
approach	O
was	O
based	O
on	O
the	O
integration	O
of	O
building	O
parameter	O
estimations	O
into	O
the	O
photogrammetry	B-Application
process	O
applying	O
a	O
hybrid	O
modeling	O
scheme	O
.	O
</s>
<s>
Multiple	O
images	O
are	O
used	O
in	O
Zeng	O
's	O
approach	O
to	O
surface	O
reconstruction	B-Algorithm
from	O
multiple	O
images	O
.	O
</s>
<s>
3D	B-Algorithm
scanning	I-Algorithm
technology	O
has	O
been	O
used	O
to	O
scan	O
space	O
rocks	O
for	O
the	O
European	O
Space	O
Agency	O
.	O
</s>
<s>
Create	O
GIS	B-Application
(	O
geographic	B-Application
information	I-Application
system	I-Application
)	O
maps	O
and	O
geomatics	O
.	O
</s>
<s>
3D	B-Algorithm
scanners	I-Algorithm
are	O
used	O
by	O
the	O
entertainment	O
industry	O
to	O
create	O
digital	O
3D	O
models	O
for	O
movies	O
,	O
video	O
games	O
and	O
leisure	O
purposes	O
.	O
</s>
<s>
3D	B-Algorithm
scanners	I-Algorithm
are	O
evolving	O
for	O
the	O
use	O
of	O
cameras	O
to	O
represent	O
3D	O
objects	O
in	O
an	O
accurate	O
manner	O
.	O
</s>
<s>
Companies	O
are	O
emerging	O
since	O
2010	O
that	O
create	O
3D	B-Algorithm
portraits	I-Algorithm
of	O
people	O
(	O
3D	B-Algorithm
figurines	I-Algorithm
or	O
3D	B-Algorithm
selfie	I-Algorithm
)	O
.	O
</s>
<s>
Rather	O
than	O
a	O
set	O
of	O
points	O
a	O
precise	O
digital	O
model	O
can	O
be	O
represented	O
by	O
a	O
polygon	B-Algorithm
mesh	I-Algorithm
,	O
a	O
set	O
of	O
flat	O
or	O
curved	O
NURBS	B-Algorithm
surfaces	I-Algorithm
,	O
or	O
ideally	O
for	O
mechanical	O
components	O
,	O
a	O
CAD	B-Application
solid	O
model	O
.	O
</s>
<s>
A	O
3D	B-Algorithm
scanner	I-Algorithm
can	O
be	O
used	O
to	O
digitise	O
free-form	O
or	O
gradually	O
changing	O
shaped	O
components	O
as	O
well	O
as	O
prismatic	O
geometries	O
whereas	O
a	O
coordinate	O
measuring	O
machine	O
is	O
usually	O
used	O
only	O
to	O
determine	O
simple	O
dimensions	O
of	O
a	O
highly	O
prismatic	O
model	O
.	O
</s>
<s>
A	O
group	O
of	O
history	O
students	O
at	O
Vancouver	O
iTech	O
Preparatory	O
Middle	O
School	O
created	O
a	O
Virtual	O
Museum	O
by	O
3D	B-Algorithm
Scanning	I-Algorithm
more	O
than	O
100	O
artifacts	O
.	O
</s>
<s>
The	O
combined	O
use	O
of	O
3D	B-Algorithm
scanning	I-Algorithm
and	O
3D	O
printing	O
technologies	O
allows	O
the	O
replication	O
of	O
real	O
objects	O
without	O
the	O
use	O
of	O
traditional	O
plaster	O
casting	O
techniques	O
,	O
that	O
in	O
many	O
cases	O
can	O
be	O
too	O
invasive	O
for	O
being	O
performed	O
on	O
precious	O
or	O
delicate	O
cultural	O
heritage	O
artifacts	O
.	O
</s>
<s>
In	O
an	O
example	O
of	O
a	O
typical	O
application	O
scenario	O
,	O
a	O
gargoyle	B-Application
model	O
was	O
digitally	O
acquired	O
using	O
a	O
3D	B-Algorithm
scanner	I-Algorithm
and	O
the	O
produced	O
3D	O
data	O
was	O
processed	O
using	O
MeshLab	B-Language
.	O
</s>
<s>
The	O
resulting	O
digital	O
3D	O
model	O
was	O
fed	O
to	O
a	O
rapid	B-Device
prototyping	I-Device
machine	O
to	O
create	O
a	O
real	O
resin	O
replica	O
of	O
the	O
original	O
object	O
.	O
</s>
<s>
Stanford	O
University	O
with	O
a	O
group	O
led	O
by	O
Marc	O
Levoy	O
used	O
a	O
custom	O
laser	O
triangulation	B-Algorithm
scanner	O
built	O
by	O
Cyberware	O
to	O
scan	O
Michelangelo	O
's	O
statues	O
in	O
Florence	O
,	O
notably	O
the	O
David	O
,	O
the	O
Prigioni	O
and	O
the	O
four	O
statues	O
in	O
The	O
Medici	O
Chapel	O
.	O
</s>
<s>
A	O
commercial	O
time	B-Device
of	I-Device
flight	I-Device
laser	O
scanner	O
,	O
the	O
DeltaSphere	O
3000	O
,	O
was	O
used	O
.	O
</s>
<s>
The	O
first	O
3D	O
models	O
of	O
cuneiform	B-Language
tablets	O
were	O
acquired	O
in	O
Germany	O
in	O
2000	O
.	O
</s>
<s>
In	O
2003	O
the	O
so-called	O
Digital	O
Hammurabi	O
project	O
acquired	O
cuneiform	B-Language
tablets	O
with	O
a	O
laser	O
triangulation	B-Algorithm
scanner	O
using	O
a	O
regular	O
grid	O
pattern	O
having	O
a	O
resolution	O
of	O
.	O
</s>
<s>
With	O
the	O
use	O
of	O
high-resolution	O
3D-scanners	O
by	O
the	O
Heidelberg	O
University	O
for	O
tablet	O
acquisition	O
in	O
2009	O
the	O
development	O
of	O
the	O
GigaMesh	B-Language
Software	I-Language
Framework	I-Language
began	O
to	O
visualize	O
and	O
extract	O
cuneiform	B-Language
characters	O
from	O
3D-models	O
.	O
</s>
<s>
2.000	O
3D-digitized	O
tablets	O
of	O
the	O
Hilprecht	O
Collection	O
in	O
Jena	B-Application
to	O
create	O
an	O
Open	O
Access	O
benchmark	O
dataset	O
and	O
an	O
annotated	O
collection	O
of	O
3D-models	O
of	O
tablets	O
freely	O
available	O
under	O
CC	O
BY	O
licenses	O
.	O
</s>
<s>
A	O
2009	O
CyArk	O
3D	B-Algorithm
scanning	I-Algorithm
project	O
at	O
Uganda	O
's	O
historic	O
Kasubi	O
Tombs	O
,	O
a	O
UNESCO	O
World	O
Heritage	O
Site	O
,	O
using	O
a	O
Leica	O
HDS	O
4500	O
,	O
produced	O
detailed	O
architectural	O
models	O
of	O
Muzibu	O
Azaala	O
Mpanga	O
,	O
the	O
main	O
building	O
at	O
the	O
complex	O
and	O
tomb	O
of	O
the	O
Kabakas	O
(	O
Kings	O
)	O
of	O
Uganda	O
.	O
</s>
<s>
A	O
fire	O
on	O
March	O
16	O
,	O
2010	O
,	O
burned	O
down	O
much	O
of	O
the	O
Muzibu	O
Azaala	O
Mpanga	O
structure	O
,	O
and	O
reconstruction	B-Algorithm
work	O
is	O
likely	O
to	O
lean	O
heavily	O
upon	O
the	O
dataset	O
produced	O
by	O
the	O
3D	B-Algorithm
scan	I-Algorithm
mission	O
.	O
</s>
<s>
Neither	O
the	O
triangulation	B-Algorithm
method	O
,	O
nor	O
the	O
time	B-Device
of	I-Device
flight	I-Device
method	O
satisfied	O
the	O
requirements	O
of	O
this	O
project	O
because	O
the	O
item	O
to	O
be	O
scanned	O
was	O
both	O
large	O
and	O
contained	O
small	O
details	O
.	O
</s>
<s>
The	O
modulated	O
light	O
scanner	O
was	O
supplemented	O
by	O
a	O
triangulation	B-Algorithm
scanner	O
which	O
was	O
used	O
to	O
scan	O
some	O
parts	O
of	O
the	O
model	O
.	O
</s>
<s>
3D	B-Algorithm
scanners	I-Algorithm
are	O
used	O
to	O
capture	O
the	O
3D	O
shape	O
of	O
a	O
patient	O
in	O
orthotics	O
and	O
dentistry	O
.	O
</s>
<s>
CAD/CAM	O
software	O
are	O
then	O
used	O
to	O
design	O
and	O
manufacture	O
the	O
orthosis	O
,	O
prosthesis	O
or	O
dental	O
implants	O
.	O
</s>
<s>
Many	O
Chairside	O
dental	O
CAD/CAM	O
systems	O
and	O
Dental	O
Laboratory	O
CAD/CAM	O
systems	O
use	O
3D	B-Algorithm
Scanner	I-Algorithm
technologies	O
to	O
capture	O
the	O
3D	O
surface	O
of	O
a	O
dental	O
preparation	O
(	O
either	O
in	O
vivo	O
or	O
in	O
vitro	O
)	O
,	O
in	O
order	O
to	O
produce	O
a	O
restoration	O
digitally	O
using	O
CAD	B-Application
software	I-Application
and	O
ultimately	O
produce	O
the	O
final	O
restoration	O
using	O
a	O
CAM	O
technology	O
(	O
such	O
as	O
a	O
CNC	O
milling	O
machine	O
,	O
or	O
3D	O
printer	O
)	O
.	O
</s>
<s>
The	O
chairside	O
systems	O
are	O
designed	O
to	O
facilitate	O
the	O
3D	B-Algorithm
scanning	I-Algorithm
of	O
a	O
preparation	O
in	O
vivo	O
and	O
produce	O
the	O
restoration	O
(	O
such	O
as	O
a	O
Crown	O
,	O
Onlay	O
,	O
Inlay	O
or	O
Veneer	O
)	O
.	O
</s>
<s>
Industrial	O
processes	O
such	O
as	O
assembly	O
are	O
complex	O
,	O
highly	O
automated	O
and	O
typically	O
based	O
on	O
CAD	B-Application
(	O
computer-aided	B-Application
design	I-Application
)	O
data	O
.	O
</s>
<s>
For	O
this	O
purpose	O
,	O
3D	B-Algorithm
scanners	I-Algorithm
are	O
applied	O
to	O
generate	O
point	O
samples	O
from	O
the	O
object	O
's	O
surface	O
which	O
are	O
finally	O
compared	O
against	O
the	O
nominal	O
data	O
.	O
</s>
<s>
The	O
process	O
of	O
comparing	O
3D	O
data	O
against	O
a	O
CAD	B-Application
model	I-Application
is	O
referred	O
to	O
as	O
CAD-Compare	O
,	O
and	O
can	O
be	O
a	O
useful	O
technique	O
for	O
applications	O
such	O
as	O
determining	O
wear	O
patterns	O
on	O
moulds	O
and	O
tooling	O
,	O
determining	O
accuracy	O
of	O
final	O
build	O
,	O
analysing	O
gap	O
and	O
flush	O
,	O
or	O
analysing	O
highly	O
complex	O
sculpted	O
surfaces	O
.	O
</s>
<s>
At	O
present	O
,	O
laser	O
triangulation	B-Algorithm
scanners	O
,	O
structured	O
light	O
and	O
contact	O
scanning	O
are	O
the	O
predominant	O
technologies	O
employed	O
for	O
industrial	O
purposes	O
,	O
with	O
contact	O
scanning	O
remaining	O
the	O
slowest	O
,	O
but	O
overall	O
most	O
accurate	O
option	O
.	O
</s>
<s>
Nevertheless	O
,	O
3D	B-Algorithm
scanning	I-Algorithm
technology	O
offers	O
distinct	O
advantages	O
compared	O
to	O
traditional	O
touch	O
probe	O
measurements	O
.	O
</s>
<s>
3D	B-Algorithm
scanning	I-Algorithm
can	O
be	O
used	O
in	O
conjunction	O
with	O
3D	O
printing	O
technology	O
to	O
virtually	O
teleport	O
certain	O
object	O
across	O
distances	O
without	O
the	O
need	O
of	O
shipping	O
them	O
and	O
in	O
some	O
cases	O
incurring	O
import/export	O
tariffs	O
.	O
</s>
<s>
In	O
the	O
future	O
,	O
as	O
3D	B-Algorithm
scanning	I-Algorithm
and	O
3D	O
printing	O
technologies	O
become	O
more	O
and	O
more	O
prevalent	O
,	O
governments	O
around	O
the	O
world	O
will	O
need	O
to	O
reconsider	O
and	O
rewrite	O
trade	O
agreements	O
and	O
international	O
laws	O
.	O
</s>
<s>
Such	O
additional	O
data	O
could	O
be	O
gps-location	O
data	O
,	O
...	O
Also	O
,	O
after	O
the	O
reconstruction	B-Algorithm
,	O
the	O
data	O
might	O
be	O
directly	O
implemented	O
into	O
a	O
local	O
(	O
GIS	B-Application
)	O
map	O
or	O
a	O
worldwide	O
map	O
such	O
as	O
Google	B-Application
Earth	I-Application
.	O
</s>
