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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004
“e Multiple measurements of image points
- Third-order design (TOD) problem. It is concerned with the
optimal improvement of a network if extra points or
observations are added to it. For the photogrammetric
monitoring networks the third-order design problem can
generally be reduced and solved for as the configuration
problem (FOD).At the beginning, the proper functions have to
be derived expressing each criterion and their subsequent
optimization has to be performed under certain constraints. The
latter is solved either directly or by trial and error procedures
(Vanicek and Krakiwsky, 1986).Now all of these steps in this
project, will be described completely.
4.2.1 Network designing : In each photogrammetric project,
it is necessary to design a network for stations of photography,
so that we can retrieve accurate and homogeneous
measurements.
4.2.2 Choosing the camera : Usually in geomatic projects,
specially in photogrammetric projects, available facilities, make
us not to choose what we want .in choosing the camera,
according to the area: kilns with high temperature that will
affect the analogue images by making film distortion and the
benefits of using digital, we choose digital camera (canon
PowerShot Pro90 IS) among two available camera in our
faculty.
The specifications of the camera are shown in table 1:
Focal length 7-70mm
Camera Type Point and Shoot
Digital Zoom 40x
Disk Media Type Compact Flash
Film Type Digital
Flash Yes
Port Capability USB
Storage Capacity (MB) 128 MB
Type Digital
Horizontal Resolution 180 dpi
Vertical Resolution 180 dpi
Width 1856 pixel
Height 1392 pixel
Geometry of photography | An instantaneous photograph
saved in CCD
Table 1. Specifications of the Canon-powershot camera
4.2.3 Calibration of the camera : For using the camera, it is
necessary to determine the accuracy of the camera, resolution
and calibration parameters in order to design the suitable places
for stations.
In this project, self calibration method is chosen and it is being
tried to solve all camera parameters during the self-calibration
procedure. The calibration parameters of the camera are:
* Interior orientation parameters of the camera (x, v, c, k),k
approximately equals with 1.
* Additional Parameters:
e Radial Lens Distortions
drx=(K1r* + K2r* + K31%)(x-x0) (3)
dry-(Klr^ 4 K2r* + K319)(y-y0)
e Decentring Lens Distortions
dpx = P1[r" + 2(x-x0)"] + 2P2(x-x0)(y-y0) (4)
dpy — P2[r - 2(y-y0)^] * 2P1(x-x0)(y-y0)
The computed calibration parameters are listed in the tables 2
and 3.
Photo K1 K2 K3
1 0.00000412 | -0.00007854 0.00003401
-0.00000731 | 0.00002158 0.00002581
2
3 0.0001191 -0.0001238
4 -0.00007115 | -0.00005585
5 0.00000804 | -0.00000595
6 -0.00002009 | 0.00000499
-0.000126
0.00003187
0.0000045
0.00002091
Photo Pl P2
1 0.00007934 -0.00008645
2 0.00000593 0.00002565
3 0.00041021 -0.0001165
4 0.00004621 -0.0001121
S -0.000003 1 -0.00000236
6 0.00001248 -0.00002505
Photo X y C
] 0.00000371 | -0.00007068 0.007
2 -0.00000658 | 0.00001942 0.007
3 0.00010719 | -0.0001114 0.006
4 -0.00006403 | -0.00005027 0.07
S 0.00000723 | -0.00000535 0.07
6 -0.00001808 | 0.00000449 0.05
Table 2. Computed additional parameters in first epoch of
observation
Photo K1 K2 K3
1 0.00026327 -0.0003996 0.00030621
2 0.00008132 -0.001143 0.0009769
3 -0.0001142 -0.0001598 0.00015805
4 -0.001208 0.00037847 0.0013068
5 -0.0006625 -0.0008283 -0.0007716
Photo P1 P2
] 0.00050801 -0.0001042
2 0.00028369 0.0007428
3 -0.00009303 0.00000806
4 0.00040703 -0.001371
5 0.00073331 -0.0001635
Photo X y e
1 0.00023694 -0.0003596 0.07
2 0.00007319 -0.001029 0.06
3 -0.0001028 -0.0001438 0.06
4 -0.001087 0.00034062 0.05
S -0.0005962 -0.0007454 0.04
Table 3. Computed additional parameters in second epoch of
observation
4.2.4 Determining number and position of stations for
camera : Depending on the imaging geometry adopted, the use
of additional stations for camera can be expected not only to
improve precision, but also to significantly enhance the
network's reliability. According to the geometry of the kiln and
limitations due to the work place, the angles of beams and
number of stations were determined, and also according to the
higher geometric stability, homogeneity of accuracy in 3
axes(X,Y,Z)(Fraser,Brown,1986) and less depth error
(Hommainejad, 1997, 1998),it is better to use convergence
system than stereo pairs. Limitations in work place, and the
geometry of the object, restrict the angle of convergency,
therefore we could use the camera stations with around 40
degree of convergency. Because of the rough nature of the area,
only 5 places were suitable for shooting and taking photographs
and at least 9 control points and all of the unknown points on