The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008 
(a) 
(b) 
(c) 
Figure 7. Height error vectors of first order rational functions in a) optimum sampling b) over sampling c) under sampling 
3.5 Results of aerial images 
In optimum sampling, we have chose 71 GCPs and 234 
check points. Distribution of control points were shown in 
figure 8. 
Regarding table 4 we can conclude: 
• Accuracy of rational functions in 
P2 = F4 
more than 
P2 * P4 
is 
• Accuracy of direct rational functions are more than 
inverse rational functions for first and second orders 
but the differences are not high for third order 
rational functions. 
Figure 8. Ground control points distribution in optimum 
sampling 
N.O.GCPs 
N.O.CKPs 
RMSECKPXYZ 
(cm) 
RMSECNPXYZ 
(cm) 
lorderRFM(P2#>4) 
71 
234 
5.572 
6.026 
2orderRFM(P2^P4) 
71 
234 
0.803 
0.726 
3orderRFM(P2#>4) 
71 
234 
0.036 
0.013 
2orderRFM(P2=P4) 
71 
234 
3.220 
2.290 
3 orderRFM(P2=P4) 
71 
234 
0.142 
0.055 
inverse lorderRFM 
(P2^P4) 
71 
234 
64.848 
64.530 
Inverse 2orderRFM 
(P2^P4) 
71 
234 
3.878 
2.925 
Inverse 3orderRFM 
(P2f?4) 
71 
234 
0.022 
0.008 
Table 4. Results obtained from aerial data in optimum sampling