In Figure 3, we introduce an error for the projection centre
coordinates in relation to the rotation axis. The amount of error is
one project unit in X-direction. The offset causes the rotation to
form a geometry where each camera location has a different
projection centre. This means that each sub-image has its own
perspective view of the scene. The result is the diverging bundle
of observation rays. Our program calculates the error as the
divergence of the observation ray in relation to the case where the
projection centre lies in the rotation axis. Thus, the width of the
spread of an observation ray bundle at the second target plane is
half of the error our simulation program outputs.
Point 1
Point 2
Figure 3. Eccentric sub-image panoramic frame camera geometry
with one project unit offset in X-direction and 20? increments.
Figure 4 illustrates the case in which the offset of the projection
centre is one project unit in the Z-direction. We can see that the
width of the spread of an observation ray bundle is similar than
in Figure 3, but the deformation of the image changes. However,
in practice the FoV limits the usefulness of such an analysis.
That is because when we have rotated the camera more than half
of our FoV of 53.13°, we run into a situation where we cannot
see our target anymore assuming the target was in the centre of
the image when the rotation started. Our simulation draws the
observation lines from each projection centre coordinates,
whether the camera actually sees the target or not. The program
can be modified to take this into account and draw only the lines
which resects with the image plane.
If we increase the offset further, we can see how the projection
centre coordinates deviate further from the rotation axis. In
Figures 5 and 6, the offset is five units and a camera constant is
four. Especially in Figure 6 this makes it hard to comprehend
how the image plane geometry is formed. The blue lines are the
image axes and at the end of each blue line is the projection
centre. Starting from each projection centre there are two
observation rays, red and green, going to the first target plane
and continuing to the second plane. At the other end of the blue
line, is the image plane.
In the case of five unit offset in Z-direction, the deformation is so
large that the cylinder we can see near the rotation axis are
actually the backsides of the image planes facing the rotation
axis and image axes are pointing outwards.
Point 1
Point 2
Figure 4. Eccentric sub-image panoramic frame camera geometry
with one project unit offset in Z-direction and 20° increments.
Point 1
Figure 5. Eccentric sub-image panoramic frame camera geometry
with five project unit offset in X-direction and 20° increments.
TET
HHH HHH HH
VIE EE PC TP EE BE TL TO EE
Figur
with f
Eccen
Figur
as spe
degre
units
The |
offset
space
In Fi;
units
and 3
an ac
plane
40 uı
show
to the
ir
Figu
direc
first
The: