Image Processing Reference
In-Depth Information
Fig. 13.3
The block diagram of the image processing part of the system. The output for each coin
is its type and center
Fig. 13.4
The field-of-view
of the camera and how it
relates to the setup
13.2 Image Acquisition
Fred had a cousin selling electronics online and Fred had convinced the cousin to
give him a good deal on a camera. He sent the link to the different cameras to Mick
and SB, and asked them to pick one. Fred had already decided that the camera
should be located 0.5 meter above the center of the vibrating table, which had the
dimensions 0
.
5m
×
0
.
5 m. The only requirement for the camera was that it should
be able to see the entire table. SB therefore made a drawing to figure out what the
field-of-view (FOV) of the camera should be, see Fig.
13.4
(a). When SB had been
staring at it for 15 min he asked Mick if he had any ideas.
“You did not pay much attention in math classes did you?”
“Will you help me or not?” SB said irritated.”
“No, but I'll give you a hint,” Mick said and drew a vertical line. “Look at that
triangle (see Fig.
13.4
(b)) and then multiply the solution by two.” SB slapped his
own face while wondering where his mind had been in all those math classes back
in high school. He soon wrote the following equation and found out that they should
get a camera with a FOV of at least 53.1°.
tan
−
1
Y/
2
X
tan
−
1
0
.
5m
/
2
0
.
5m
=
·
=
·
=
·
=
FOV
2
α
2
2
53
.
1°
(13.1)
where
Y
is the width of the table and
X
is the distance between the camera and
table.
