In: Wagner W., Székely. B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
There were 21 image points with ground points coordinates 
surveyed from 1:10,000 scale relief map. 
5.1 Experiment 1: Direct Geocoding to the Earth Ellipsoid 
The ephemeris and attitude data acquired from 
supplementary file of the image were used, and Gauss 
Since the misaligned angle of sensor axis relative to satellite 
body axis was not available to the public, the three attitude 
angles were all set to 0; meanwhile the DEM data were used 
due to significant change of the terrain. The precision of direct 
geocoding was acquired by comparing coordinates of 21 
homonymy points from geocoding image and the relief map 
points, and the results were listed in the “direct geocoding” 
column of table 1. 
The results also indicated that all the check points had 
obvious systemic errors both in azimuth and range directions. 
5.2 Experiment 2: Orthophoto correction with sparse 
GCPs and DEM data. 
In this experiment, two surveying points were selected as 
control points (distributed on the top right and bottom left 
comers of the image) and 19 as check points so as to refine the 
image orientation elements, and the images were corrected with 
refined orientation elements and DEM data. 
Through comparing calculation results and the known data of 
surveying object, errors of ground control points (GCPs) and 
check points (CPs) were listed in the “Orthophoto correction” 
column of table 1. 
6. CONCLUSIONS 
The collinearity equation model of radar images has such 
shortcomings as poor rigorousness and practicality; Range- 
Doppler model does not apply to the existing processing 
algorithms of photogrammetric data. With elements of exterior 
orientation as the orientation parameters, in this study a new 
imaging equation of radar image was constructed —Range- 
Coplanarity equation. The imaging equation reflected the 
imaging mechanism of the radar images in the direction of 
range and the direction of orientation, and manifested the 
attribute of the image point coordinate as independent observed 
value of photogrammetry so that the positioning of radar image 
are able to easily adopt the mature algorithms of 
photogrammetric data processing of optical image.lt also has 
simple form and requires less orientation parameters than R-D 
model and collinearity equation. 
In the years past, techniques of sensor positioning and 
attitude determination technique had been greatly developed. 
With the utilization of them, the image mapping without GCPs 
will become a trend in future. Therefore, this image equation 
will bring convenience for radar image rectification, stereo 
positioning, block adjustment, and InSAR baseline calculation 
in photogrammetry. At present, related studies are still being 
kept on by us. 
7. ACKNOWLEDGEMENT 
This study is fully supported by National Natural Science 
Foundation of China (Project No. 40871167) and State 863 
projects(Project No.200*AA12****). 
8. REFERENCES 
[1] Leberl F. Radar grammetry for Image Interpretation, 
ITC Technical Report, 1978 
[2] F. Leberl. Radar grammetric processing[M]. Artech 
House, 1990 
[3] GKonecny, W.Schuhr. Reliability of Radar Image 
Data[J]. ISPRS Comm. I Symposium, 1988 
[4] Chunquan Cheng, Kazhong Deng, Jixian Zhang , Li Zhang. 
Block Adjustment of Airborne Imagery in Geocentric 
Orthogonal Coordinate System. ICIECS2009. 
Exp content 
Direct 
Geocoding 
Orthophoto 
Correction 
Unit: (pixel) 
21 CPs 
2GCPs 
19CPs 
RM S_x(azimuth) 
3.53 
0.44 
1.26 
RMS_y(range) 
4.71 
0.40 
1.27 
RMS_xy 
5.88 
0.59 
1.79 
MAXerror(x) 
7.07 
0.11 
3.72 
MAX error(y) 
5.77 
-0.12 
2.97 
Table 1 The statistics of precision of check points