<s>
A	O
Réseau	B-General_Concept
plate	I-General_Concept
is	O
a	O
transparent	O
sheet	O
of	O
glass	O
or	O
plastic	O
engraved	O
with	O
a	O
grid	O
of	O
crosshatches	O
called	O
fiducial	B-Architecture
markers	I-Architecture
.	O
</s>
<s>
When	O
the	O
frame	O
is	O
exposed	O
the	O
fiducial	B-Architecture
markers	I-Architecture
scatter	O
incoming	O
light	O
,	O
creating	O
a	O
permanent	O
shadow	O
on	O
the	O
negative	O
.	O
</s>
<s>
The	O
fiducial	B-Architecture
markers	I-Architecture
on	O
a	O
Réseau	B-General_Concept
plate	I-General_Concept
are	O
sometimes	O
called	O
reticles	O
.	O
</s>
<s>
The	O
Latin	O
root	O
of	O
fiducial	B-Architecture
means	O
trust	O
,	O
confidence	O
;	O
fiducial	B-Architecture
markers	I-Architecture
are	O
trustworthy	O
reference	O
points	O
.	O
</s>
<s>
If	O
the	O
film	O
negative	O
is	O
properly	O
printed	O
the	O
fiducial	B-Architecture
markers	I-Architecture
will	O
be	O
evenly	O
spaced	O
on	O
the	O
positive	O
image	O
.	O
</s>
<s>
When	O
used	O
for	O
photogrammetry	B-Application
,	O
multiple	O
images	O
can	O
be	O
combined	O
using	O
the	O
fiducial	B-Architecture
marks	I-Architecture
and	O
knowledge	O
of	O
the	O
camera	O
geometry	O
to	O
enable	O
measurement	O
of	O
distances	O
between	O
objects	O
in	O
the	O
images	O
.	O
</s>
<s>
The	O
Hasselblad	O
lunar	O
surface	O
data	O
camera	O
was	O
fitted	O
with	O
a	O
Réseau	B-General_Concept
plate	I-General_Concept
.	O
</s>
<s>
The	O
Réseau	B-General_Concept
plate	I-General_Concept
was	O
made	O
of	O
glass	O
and	O
was	O
fitted	O
to	O
the	O
back	O
of	O
the	O
camera	O
body	O
,	O
extremely	O
close	O
to	O
the	O
film	O
plane	O
.	O
</s>
<s>
The	O
Réseau	B-General_Concept
plate	I-General_Concept
was	O
engraved	O
with	O
a	O
5	O
×	O
5	O
grid	O
of	O
crosses	O
.	O
</s>
<s>
The	O
crosses	O
(	O
also	O
known	O
as	O
fiducials	B-Architecture
)	O
were	O
recorded	O
on	O
every	O
exposed	O
frame	O
and	O
provided	O
a	O
means	O
of	O
determining	O
angular	O
distances	O
between	O
objects	O
in	O
the	O
field-of-view	O
.	O
</s>
