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5. EXPERIMENTS
There are two experiments in this paper. In these experiments, a
small 2D plane control brand is employed. Its size is
350mmx350mm,and there are 32 code points, which the
distance of every pairs of adjacent points is 70mm in horizonal
and vertical direction. The selected three or six points(in
rectangles)located at the left-up comer are regarded as the
control points of a small control frame, and the other points (in
circles) are regarded as check points, shown as in Figure 4.
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Figure 4. Diagram of control points and check points
distribution (a) three control points and check points (b) six
control points
A Canon 450D SLR digital camera with 28 mm lens is used to
take six multi-intersection images which have 4272x2848 pixels.
The top right number on each image expresses the image
number, shown as in Figure 5. PSO algorithm is utilized to
calculate the approximate values of exterior orientation
elements which will be employed in bundle adjustment to
compute the object space coordinates of check points. Then we
compare the computed the object space coordinates of check
points with their known object space coordinates to compute
accuracy.
Figure 5. Six multi-intersection images
5.1 Experiment 1. using three control points
Six images (shown in Figure 5.) are taken and their approximate
values of exterior orientation elements are searched by PSO
respectively. Twelve code points are selected as check points in
the control brand, shown as in Figure 4(a). The exterior
orientation elements calculated by PSO and Bundle adjustment
are shown in Table 2. The difference of check points object
coordinates are shown in Table 3.
39
No |Method| X; (mm) | Ys (mm)| Zs (mm) act) Gain b Am
Bundle| 69.99 201.85 2473.38 0.04410 -0.02370| -0.03050
U1 pso | 440.71] 254.53 322320| 0.22203 0.04619 -0.02440
Bundle| 72.07] 145.46 2430.21] 0.03140 -0.00070| -0.03960
2 PSO | -481.95| -105.09 3156.94 0.23223 0.15709 -0.05091
Bundle| 597.94 -23.307 2349.79 -0.16210 0.07060 -0.00260
: PSO | 408.84 -105.23 3189.49 -0.03093 0.15973 -0.00643
Bundle | 1003.19) -23.556 2403.45] -0.34150| 0.06340 0.04710
4 PSO | 1387.67 -97.15 3092.11| -0.35570| 0.15239| 0.05028
Bundle| -311.44| -248.88 2362.60 0.20010 0.15760 -0.06770
s PSO | -545.50 -460.54 3079.83 0.26537 0.26431| -0.08714
Bundle | 1257.26 -304.67 2479.63 -0.40820, 0.17140 0.02230
s PSO | 1700.98 -470.30 3130.53 -0.42452 0.26081| 0.03090)
Table 2. Exterior orientation elements calculated by PSO and
Bundle adjustment (three control points)
Difference of coordinate Difference of coordinate
No (mm) No (mm)
AX AY AZ AX ^Y AZ
1 0.001 | -0.009| 0.001] 18 | -0.151| -0.191| 0.526
5 | -0.192| -0.053| -0.158 | 21 0.041 -0.180| 0.530
8 0.013 | -0.019| 0.113] 23 | -0.306| -0.480| 0.599
10 | -0.174| -0.097| 0.138] 25 | -0.738| -0.582| 0.685
12 | -0.357| -0.06| -0.054| 28 | -0.154| -0.495| 1.108
13 0.001 | -0.001| 0.387] 31 | -0.796| -0.746) 1.051
Table 3. Difference of check points object coordinates(three
control points)
From Table 3, the mean square error of three directions are my
=+0.356mm, my==0.349mm, m;==0.572mm respectively,
and the point mean square error is mp—+0.759mm. Under this
condition, we can not obtain the approximate values of exterior
orientation elements by space resection.
5.2 Experiment 2. using six control point
Six images (shown in Figure 5.) are taken and their approximate
values of exterior orientation elements are searched by PSO
respectively. Twelve code points are selected as check points in
the control brand, shown as in Figure 4(b). The exterior
orientation elements calculated by PSO and Bundle adjustment
are shown in Table 4. The difference of check points object
coordinates are shown in Table 5.