tanbul 2004 
placement. 
WS can be 
away from 
degree, the 
nt is 323 
' ellipticity 
ting datum 
and flight 
tangential 
ind change 
tangential 
  
sarded as a 
of ground 
| is ground 
JS, AN' is 
ss through 
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lant angle. 
because of 
; modified 
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the follow: 
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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV. Part B2. Istanbul 2004 
However, according to expression (4), dx should be linearized. 
E x=agt+a, X+a,Y+a;X +a, XY +as Y2-(x+dx) 
dax = (hJR" +(H *2—h)*h/ s)dH 
So dFx = da, + Xda, + Yda, + X*da, + XYda, (6) 
+ Y’da, + (hJR? +(H *2—h)*h/s)dH 
Making use of (6)1the distortion in x direction can be corrected 
by polynomial orthorectification 
Suppose 
Because 
3. DATA USED 
According to the above-mentioned method, we have designed 
the processing software for the SAR image. And then, using 
ERS !RadarSat lairborne SAR image data, we go on some 
experiments with this method, and have received results of 
satisfaction. 
4. RESULTS AND DISCUSSION 
4.1 Experiment on ERS-2 image Orthorectification 
Site: Chengdu region, Sichuan province 
Flight height: 824000m 
Resolution: 25m 
Result Accuracy: 
Error X: 1.7 pixels: 
Error Y: 0.5 pixels; 
Distance error: 1.8 pixels. 
  
DP. Ee. AT B MEE 
Figure 3. ERS-2 image in Chengdu 
141 
   
Figure 4. Chengdu ortho-image 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
No |X y Z Dx Dy 
0 364850 | 394750 585 0.5 0.1 
1 372900 | 353900 | 460 0.8 1.0 
2 379803 | 411945 605 -0.1 -0.6 
3 406012 | 387608 492 -0.8 0.4 
4 432327 | 347533 465 -1.2 1.1 
= 430100 | 410300 | 466 0.5 0.6 
6 375875 | 321730 | 415 -0.9 -0.8 
7 3753738 | 385375 513 -0.7 0.2 
8 403650 | 356250 | 432 0.1 -1.5 
9 436000 | 362000 | 459 0.4 -1.5 
10 | 408500 | 332750 | 456 0.1 1.0 
  
  
  
  
  
ERIE Le 
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“10 
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RARE 
Table 1. Error of control points. The unit of X, Y, and Z are 
meter, and that of Dx and Dy are pixel. 
  
  
Figure 5. Chengdu error distribution figure 
4.2 Experiment 
Site: Dali region, Yunnan province 
Flight height: 792594m 
Original slant range: 1058128.9m 
Resolution: 25m 
Result accuracy: 
Error X: 1.4 pixels 
Error Y: 1.7 pixels 
Distance error : 2.2 pixels 
on RadarSat image Orthorectification