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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. 
Go: 
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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.