<s>
A	O
fiducial	B-Architecture
marker	I-Architecture
or	O
fiducial	B-Architecture
is	O
an	O
object	O
placed	O
in	O
the	O
field	O
of	O
view	O
of	O
an	O
imaging	O
system	O
that	O
appears	O
in	O
the	O
image	O
produced	O
,	O
for	O
use	O
as	O
a	O
point	O
of	O
reference	O
or	O
a	O
measure	O
.	O
</s>
<s>
In	O
high-resolution	O
optical	O
microscopy	O
,	O
fiducials	B-Architecture
can	O
be	O
used	O
to	O
actively	O
stabilize	O
the	O
field	O
of	O
view	O
.	O
</s>
<s>
In	O
physics	O
,	O
3D	O
computer	O
graphics	O
,	O
and	O
photography	O
,	O
fiducials	B-Architecture
are	O
reference	O
points	O
:	O
fixed	O
points	O
or	O
lines	O
within	O
a	O
scene	O
to	O
which	O
other	O
objects	O
can	O
be	O
related	O
or	O
against	O
which	O
objects	O
can	O
be	O
measured	O
.	O
</s>
<s>
Cameras	O
outfitted	O
with	O
Réseau	B-General_Concept
plates	I-General_Concept
produce	O
these	O
reference	O
marks	O
(	O
also	O
called	O
Réseau	O
crosses	O
)	O
and	O
are	O
commonly	O
used	O
by	O
NASA	O
.	O
</s>
<s>
Such	O
marks	O
are	O
closely	O
related	O
to	O
the	O
timing	O
marks	O
used	O
in	O
optical	B-Application
mark	I-Application
recognition	I-Application
.	O
</s>
<s>
Airborne	O
geophysical	O
surveys	O
also	O
use	O
the	O
term	O
"	O
fiducial	B-Architecture
"	O
as	O
a	O
sequential	O
reference	O
number	O
in	O
the	O
measurement	O
of	O
various	O
geophysical	O
instruments	O
during	O
a	O
survey	O
flight	O
.	O
</s>
<s>
This	O
method	O
of	O
positioning	O
has	O
since	O
been	O
replaced	O
by	O
GPS	O
,	O
but	O
the	O
term	O
"	O
fiducial	B-Architecture
"	O
continues	O
to	O
be	O
used	O
as	O
the	O
time	O
reference	O
for	O
data	O
measured	O
during	O
flights	O
.	O
</s>
<s>
In	O
applications	O
of	O
augmented	B-General_Concept
reality	I-General_Concept
,	O
fiducials	B-Architecture
help	O
resolve	O
several	O
problems	O
of	O
integration	O
between	O
the	O
real	O
world	O
view	O
and	O
the	O
synthetic	O
images	O
that	O
augment	O
it	O
.	O
</s>
<s>
Fiducials	B-Architecture
of	O
known	O
pattern	O
and	O
size	O
can	O
serve	O
as	O
real	O
world	O
anchors	O
of	O
location	O
,	O
orientation	O
and	O
scale	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
fiducial	B-Architecture
printed	O
on	O
one	O
page	O
of	O
an	O
augmented	B-General_Concept
reality	I-General_Concept
popup	O
book	O
would	O
identify	O
the	O
page	O
to	O
allow	O
the	O
system	O
to	O
select	O
the	O
augmentation	O
content	O
.	O
</s>
<s>
A	O
slightly	O
more	O
complex	O
example	O
would	O
be	O
multiple	O
fiducials	B-Architecture
,	O
each	O
attached	O
to	O
an	O
individual	O
piece	O
in	O
an	O
augmented	B-General_Concept
reality	I-General_Concept
board	O
game	O
.	O
</s>
<s>
The	O
appearance	O
of	O
markers	O
in	O
images	O
may	O
act	O
as	O
a	O
reference	O
for	O
image	B-Algorithm
scaling	I-Algorithm
,	O
or	O
may	O
allow	O
the	O
image	O
and	O
physical	O
object	O
,	O
or	O
multiple	O
independent	O
images	O
,	O
to	O
be	O
correlated	O
.	O
</s>
<s>
By	O
placing	O
fiducial	B-Architecture
markers	I-Architecture
at	O
known	O
locations	O
in	O
a	O
subject	O
,	O
the	O
relative	O
scale	O
in	O
the	O
produced	O
image	O
may	O
be	O
determined	O
by	O
comparison	O
of	O
the	O
locations	O
of	O
the	O
markers	O
in	O
the	O
image	O
and	O
subject	O
.	O
</s>
<s>
In	O
applications	O
such	O
as	O
photogrammetry	B-Application
,	O
the	O
fiducial	B-Architecture
marks	I-Architecture
of	O
a	O
surveying	O
camera	O
may	O
be	O
set	O
so	O
that	O
they	O
define	O
the	O
principal	O
point	O
,	O
in	O
a	O
process	O
called	O
"	O
collimation	O
"	O
.	O
</s>
<s>
Some	O
sets	O
of	O
fiducial	B-Architecture
markers	I-Architecture
are	O
specifically	O
designed	O
to	O
allow	O
rapid	O
,	O
low-latency	O
detection	O
of	O
6D	O
position	O
estimation	O
(	O
3D	O
location	O
and	O
3D	O
orientation	O
)	O
and	O
identity	O
of	O
hundreds	O
of	O
unique	O
fiducial	B-Architecture
markers	I-Architecture
.	O
</s>
<s>
For	O
example	O
,	O
the	O
ArUco	O
markers	O
,	O
the	O
WhyCon	O
marker	O
,	O
WhyCode	O
markers	O
,	O
"	O
amoeba	O
"	O
reacTIVision	O
fiducials	B-Architecture
,	O
the	O
d-touch	O
fiducials	B-Architecture
,	O
or	O
the	O
TRIP	O
circular	O
barcode	O
tags	O
(	O
ringcodes	O
)	O
.	O
</s>
<s>
Fiducial	B-Architecture
markers	I-Architecture
are	O
used	O
in	O
a	O
wide	O
range	O
of	O
medical	B-Application
imaging	I-Application
applications	O
.	O
</s>
<s>
Images	O
of	O
the	O
same	O
subject	O
produced	O
with	O
two	O
different	O
imaging	O
systems	O
may	O
be	O
correlated	O
by	O
placing	O
a	O
fiducial	B-Architecture
marker	I-Architecture
in	O
the	O
area	O
imaged	O
by	O
both	O
systems	O
.	O
</s>
<s>
By	O
this	O
method	O
,	O
functional	O
information	O
from	O
SPECT	O
or	O
positron	B-Application
emission	I-Application
tomography	I-Application
can	O
be	O
related	O
to	O
anatomical	O
information	O
provided	O
by	O
magnetic	O
resonance	O
imaging	O
(	O
MRI	O
)	O
.	O
</s>
<s>
Similarly	O
,	O
fiducial	B-Architecture
points	O
established	O
during	O
MRI	O
can	O
be	O
correlated	O
with	O
brain	O
images	O
generated	O
by	O
magnetoencephalography	O
to	O
localize	O
the	O
source	O
of	O
brain	O
activity	O
.	O
</s>
<s>
Such	O
fiducial	B-Architecture
points	O
or	O
markers	O
are	O
often	O
created	O
in	O
tomographic	O
images	O
such	O
as	O
computed	O
tomography	O
,	O
magnetic	O
resonance	O
and	O
positron	B-Application
emission	I-Application
tomography	I-Application
images	O
using	O
devices	O
such	O
as	O
the	O
N-localizer	O
and	O
Sturm-Pastyr	O
localizer	O
.	O
</s>
<s>
In	O
electrocardiography	B-Application
(	O
ECG	B-Application
)	O
,	O
fiducial	B-Architecture
points	O
are	O
landmarks	O
on	O
the	O
ECG	B-Application
complex	O
such	O
as	O
the	O
isoelectric	B-Application
line	I-Application
(	O
PQ	O
junction	O
)	O
,	O
and	O
onset	O
of	O
individual	O
waves	O
such	O
as	O
PQRST	O
.	O
</s>
<s>
Commonly	O
used	O
fiducial	B-Architecture
markers	I-Architecture
are	O
fluorescently	O
labelled	O
monomers	O
of	O
bio-polymers	O
.	O
</s>
<s>
These	O
systems	O
combine	O
fiducial	B-Architecture
markers	I-Architecture
and	O
machine	O
vision	O
to	O
output	O
the	O
location	O
and	O
orientation	O
of	O
colony	O
members	O
multiple	O
times	O
per	O
second	O
and	O
have	O
,	O
among	O
other	O
insights	O
,	O
revealed	O
the	O
social	O
network	O
structure	O
of	O
ant	O
Camponotus	O
fellah	O
.	O
</s>
<s>
In	O
radiotherapy	O
and	O
radiosurgical	O
systems	O
,	O
fiducial	B-Architecture
points	O
are	O
landmarks	O
in	O
the	O
tumour	O
to	O
facilitate	O
correct	O
targets	O
for	O
treatment	O
.	O
</s>
<s>
In	O
neuronavigation	O
,	O
a	O
"	O
fiducial	B-Architecture
spatial	O
coordinate	O
system	O
"	O
is	O
used	O
as	O
a	O
reference	O
,	O
for	O
use	O
in	O
neurosurgery	O
,	O
to	O
describe	O
the	O
position	O
of	O
specific	O
structures	O
within	O
the	O
head	O
or	O
elsewhere	O
in	O
the	O
body	O
.	O
</s>
<s>
Such	O
fiducial	B-Architecture
points	O
or	O
landmarks	O
are	O
often	O
created	O
in	O
magnetic	O
resonance	O
imaging	O
and	O
computed	O
tomography	O
images	O
by	O
using	O
the	O
N-localizer	O
or	O
Sturm-Pastyr	O
localizer	O
.	O
</s>
<s>
In	O
printed	O
circuit	O
board	O
(	O
PCB	O
)	O
manufacturing	O
,	O
fiducial	B-Architecture
marks	I-Architecture
,	O
also	O
known	O
as	O
circuit	O
pattern	O
recognition	O
marks	O
,	O
allow	O
SMT	O
placement	O
equipment	O
to	O
accurately	O
locate	O
and	O
place	O
parts	O
on	O
boards	O
.	O
</s>
<s>
Alternatively	O
,	O
it	O
is	O
possible	O
to	O
use	O
clear	O
solder-mask	O
lacquer	O
to	O
cover	O
the	O
fiducials	B-Architecture
.	O
</s>
<s>
In	O
order	O
to	O
minimize	O
rounding	B-Algorithm
errors	I-Algorithm
it	O
was	O
good	O
practice	O
to	O
place	O
fiducials	B-Architecture
in	O
the	O
same	O
grid	O
(	O
or	O
some	O
multiple	O
of	O
it	O
)	O
that	O
was	O
used	O
to	O
place	O
the	O
parts	O
,	O
however	O
,	O
this	O
is	O
n't	O
always	O
possible	O
on	O
high-density	O
boards	O
nor	O
is	O
it	O
a	O
requirement	O
any	O
more	O
with	O
modern	O
high-precision	O
machines	O
.	O
</s>
<s>
Consequently	O
,	O
a	O
typical	O
PCB	O
will	O
have	O
multiple	O
fiducials	B-Architecture
to	O
allow	O
placement	O
robots	O
to	O
precisely	O
determine	O
the	O
board	O
's	O
orientation	O
.	O
</s>
<s>
By	O
measuring	O
the	O
location	O
of	O
the	O
fiducials	B-Architecture
relative	O
to	O
the	O
board	O
plan	O
stored	O
in	O
the	O
machine	O
's	O
memory	O
,	O
the	O
machine	O
can	O
reliably	O
compute	O
the	O
degree	O
to	O
which	O
parts	O
must	O
be	O
moved	O
relative	O
to	O
the	O
plan	O
,	O
called	O
offset	O
,	O
to	O
ensure	O
accurate	O
placement	O
.	O
</s>
<s>
Using	O
three	O
fiducials	B-Architecture
enables	O
the	O
machine	O
to	O
determine	O
PCB	O
offset	O
in	O
both	O
the	O
X	O
and	O
Y	O
axes	O
,	O
as	O
well	O
as	O
to	O
determine	O
if	O
the	O
board	O
has	O
rotated	O
during	O
clamping	O
,	O
allowing	O
the	O
machine	O
to	O
rotate	O
parts	O
to	O
be	O
placed	O
to	O
match	O
.	O
</s>
<s>
Such	O
fiducials	B-Architecture
are	O
also	O
called	O
global	O
fiducials	B-Architecture
.	O
</s>
<s>
Global	O
fiducials	B-Architecture
are	O
also	O
used	O
in	O
conjunction	O
with	O
stencil	O
printing	O
.	O
</s>
<s>
Parts	O
requiring	O
a	O
very	O
high	O
degree	O
of	O
placement	O
precision	O
,	O
such	O
as	O
ball	B-Algorithm
grid	I-Algorithm
array	I-Algorithm
packages	O
,	O
may	O
have	O
additional	O
local	B-Architecture
fiducials	I-Architecture
near	O
the	O
package	O
placement	O
area	O
of	O
the	O
board	O
to	O
further	O
fine-tune	O
the	O
targeting	O
.	O
</s>
<s>
Local	B-Architecture
fiducial	I-Architecture
,	O
however	O
,	O
cannot	O
be	O
used	O
in	O
the	O
stencil	O
printing	O
process	O
.	O
</s>
<s>
Conversely	O
,	O
low	O
end	O
,	O
low-precision	O
boards	O
may	O
only	O
have	O
two	O
fiducials	B-Architecture
,	O
or	O
use	O
fiducials	B-Architecture
applied	O
as	O
part	O
of	O
the	O
screen	O
printing	O
process	O
applied	O
to	O
most	O
circuit	O
boards	O
.	O
</s>
<s>
Some	O
very	O
low-end	O
boards	O
may	O
use	O
the	O
plated	O
mounting	O
screw	O
holes	O
as	O
fiducials	B-Architecture
,	O
although	O
this	O
yields	O
very	O
low	O
accuracy	O
.	O
</s>
<s>
For	O
prototyping	O
and	O
small	O
batch	O
production	O
runs	O
,	O
the	O
use	O
of	O
a	O
fiducial	B-Architecture
camera	O
can	O
greatly	O
improve	O
the	O
process	O
of	O
board	O
fabrication	O
.	O
</s>
<s>
By	O
automatically	O
locating	O
fiducial	B-Architecture
markers	I-Architecture
,	O
the	O
camera	O
automates	O
board	O
alignment	O
.	O
</s>
<s>
In	O
color	O
printing	O
,	O
fiducials	B-Architecture
—	O
also	O
called	O
"	O
registration	O
black	O
"	O
—	O
are	O
used	O
at	O
the	O
edge	O
of	O
the	O
cyan	O
,	O
magenta	O
,	O
yellow	O
and	O
black	O
(	O
CMYK	O
)	O
printing	O
plates	O
so	O
that	O
they	O
can	O
be	O
correctly	O
aligned	O
with	O
each	O
other	O
.	O
</s>
<s>
"	O
Banana	B-Operating_System
for	O
scale	O
"	O
refers	O
to	O
an	O
Internet	O
meme	O
involving	O
using	O
a	O
banana	B-Operating_System
as	O
a	O
fiducial	B-Architecture
marker	I-Architecture
.	O
</s>
<s>
The	O
meme	O
began	O
in	O
August	O
2010	O
,	O
where	O
a	O
man	O
posted	O
to	O
Facebook	B-Application
a	O
picture	O
of	O
a	O
safe	O
with	O
a	O
banana	B-Operating_System
beside	O
it	O
.	O
</s>
<s>
From	O
there	O
,	O
the	O
meme	O
spread	O
primarily	O
via	O
Reddit	B-Application
;	O
The	O
Daily	O
Dot	O
remarked	O
that	O
"	O
[	O
the	O
meme ]	O
had	O
become	O
a	O
hilarious	O
game	O
with	O
redditors	O
try	O
to	O
one	O
up	O
each	O
other	O
.	O
</s>
