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Poster Session 1
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Image Geometric Simulation And Orientation Modeling For Rocsat-2
4. Experimental Results
We simulate two images based on the assumed orbit and orthorectified aerial images for the target area. The resolution of the orthoimage is 1m*1m(fig.5).A simulated DTM with 1m*1m is also prepared(fig.6).The orbit passes the Strait near Taiwan. The attitude angles for each of the images are:
Image1: roll=14.33125 °, pitch=13.29759 °, yaw=0 °
Image2: roll=15.81852 °, pitch=-10.50034 °, yaw=0 °
Fig.7 and fig.8 represent the two simulated images.
Figure 5. Target Image |
Figure 6. Target DTM |
Figure 7. Simulated Image1 |
Figure 8. Simulated Image2 |
Considering different combinations of systematic and random errors, the accuracy analyses for 5 GCPs are summarized in Table1. In which,121 checkpoints are analyzed. The systematic errors are not linear in terms of sampling time. The random errors are Gaussian distributed. It is observed that the systematic errors are well compensated. While random errors behave differently. This is what it reflects the characteristics of "Random".
Table1. Error Analyses by Checkpoints
| Error Inclusion |
RMSE(m) |
| Type |
Quantity
(each component) |
E |
N |
Systematic
position |
450m |
0.53 |
0.25 |
| Systematic Attitude |
30" |
0.13 |
0.20 |
Systematic
Position + Attitude |
450m
30" |
0.41 |
0.13 |
| Random Position |
1m |
1.08 |
1.00 |
| Random Attitude |
0.25" |
1.34 |
1.28 |
Random
Position + Attitude |
1m
0.25" |
1.34 |
1.60 |
Systematic and
Random(Position
+ Attitude) |
Systematic:450m
30"
Random:1m
0.25" |
1.33 |
1.60 |
5. Conclusions
We developed a scheme to simulated ROCSAT-2 Images. The scheme considers the satellite flying characteristics and imaging behaviors. Systematic and random errors are simulated in the scheme. A scheme for modeling precision orientation parameters is also established. Experimental results indicate that systematic errors may be compensated while random errors are still kept random. The RMSE from ground checkpoints reflects the random errors of inclusion consistently.
Only panchromatic images are simulated and tested. For multi-spectral images, the geometric behavior is expected to be similar. Because this investigation only concerns about the geometrical property, the simulated images do not consider the radiometric characteristics. Further investigation on radiometry is suggested.
References
- Chen, L.C., and Chang, L.Y., 1998, "Three-Dimensional Positioning Using SPOT Stereostrips with Sparse Control", Journal of Surveying Engineering, ASCE, Vol.124, No.2., pp.63-72
- Gerald, C.F., and Wheatley,p.p.,1994,"Applied Numerical Analysis", Addison -Wesley Publishing Co., Reading, Mass.
- NSPO, 2000,"ROCSAT-2 Satellite Property " , http://www.nspo.gov.tw/e40/ welcome.htm
- Tseng, C.Y., 1983, "Remote Sensing of the Atmosphere: Principles and Applications ", Wen -Ying Qc871.T83, TAIWAN. (in Chinese)
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