1. Radargrammetry of High Resolution Synthetic Aperture Radar Onboard KOMPSAT-5
Hoonyol Lee
Department of Geophysics
Kangwon National University
Homepage:

2. Contents Overview of KOMPSAT-5 COSI Radargrammetry of KOMPSAT-5 COSI
Equator
Mid Latitude
Antarctica
Conclusion

3. Overview of KOMPSAT-5 COSI
X-band
Altitude: 550km
Inclination: 97.6 deg
Dawn-dusk orbit
06:00 am Mean Local Time of Ascending Node
15+1/28 revolutions per day
Nodal Period: minutes
28D421R (28 days revisit time after 421 revolutions)
Ground speed: 6.97 km/s
Successive Orbit Distance: 2665 km (no image overlap between two successive orbits)
Distance between adjacent pass: 95 km at equator

4. KOMPSAT-5 Orbit Elements
Epoch: 2009JUN01
00:00:00 UTC
Mean Orbit
(J2000)
Osculating Orbit
Semi-Major Axis (km)
Eccentricity
Inclination (deg)
R.A. of Ascending Node (deg)
Argument of Perigee (deg)
90.0
Mean Anomaly (deg)
270.0

5. Ascending Node Pass (Dawn)
Orbit Number
2665 km
© KARI
Day Number

6. Descending Node Pass (Dusk)
Orbit Number
95 km
© KARI
Day Number

7. Spot Mode © KARI Imaging Time of 1 Scene = 3 sec
In-Cal and Fin-Cal Time = ( ) sec
Maximum Time btw. Target Change (20-45 deg) = 2 sec
Minimum Number of HR Images in 2 minutes = 22
© KARI

8. Stripmap Mode © KARI Imaging Time = 2 continuous minutes
Maximum Time btw. Target Change (20-45 deg) = 1.5 sec
© KARI

9. ScanSAR Mode © KARI Imaging Time = 2 continuous minutes
Maximum Time btw. Target Change (20-45 deg) = 4 sec
© KARI

10. Radargrammetry
Stereographic mapping with two SAR images taken at different incidence angles
All weather, day & night, high-resolution SAR
Horizontal Resolution: ~ 8x8 pixels for cross-correlation
Vertical Resolution ~ incidence angles and their difference
Severe topographic distortion

11. Spaceborne Topographic Mappers
Radargrammetry
InSAR (Single Pass)
Photogrammetry
Lidar
EM Spectrum
Microwave
Optics
All weather, Day & night ○ ×
Topographic conformality
(○ : L, R Merge)
(○: L, R Merge)
Horizontal Resolution (Pixels)
8x8
(Cross-Correlation)
3x3
(Spectral Filtering) 1
Relative Height Resolution
1~2 pixel
meter
~ 1 pixel
Past Systems
Magellan SAR
SRTM
Numerous in repeat pass -
Current Systems
Radarsat-1
Single pass: TERRA ASTER, SPOT-5 HRS, ALOS PRISM
ICESAT GLAS
Future Systems
Radarsat-2,
KOMPSAT-5
TanDEM-X ?
Major Problem
Topographic distortion
No system in operation
Cloud

12. SSR vs. OSR Opposite-Side Radargrammetry Same-Side Radargrammetry
Incidence angles
Same-Side Radargrammetry (SSR)
Opposite-Side Radargrammetry (OSR)
Vertical Resolution: OSR is better than SSR
Severe topographic distortion: SSR is better than OSR
Same-Side Radargrammetry
Moderate sensitivity to height
Moderate distortion
Error in textureless area
Opposite-Side Radargrammetry
High sensitivity to height
Severe distortion
Error in textureless area

13. SSR Geometry

14. OSR Geometry

15. Radargrammetry – An example
Magellan SAR data of Lullin Impact Crater, Venus (Lee et al. 2003)
Left-look, 44.2 °
Left-look, 25.1 °
Right-look, °

16. SSR vs. OSR Anaglyph DEM Same-Side Radargrammetry
Moderate sensitivity to height
Moderate distortion
Error in textureless area
Opposite-Side Radargrammetry
High sensitivity to height
Severe distortion
Error in textureless area
Anaglyph
DEM

17. KOMPSAT-5 COSI Imaging Modes
Adjacent Pass
95 km
0 km
Nadir
185 km
490 km
Altitude
550km
Nominal
675 km
Spot (1 m), 5km, 22 scenes
Extended
Strip map (3 m), 30 km x 800 km
ScanSAR (20m), 100 km x 800 km
20 °
185 km
Nominal
305 km
45 °
55 °
Coverage
490 km
Extended
185 km

18. Number of Pass for a Ground Target
Condition for Complete Coverage of SSR:
N=C/A>2
N: number of pass, C: Image Coverage width,
A: Adjacent pass distance(=95km at equator)
Incidence Angles
Ground Coverage from Nadir
Image Coverage width
Number of Pass
Nominal
20°~45°
185~490 km
305 km
3.2
Extended
45°~55°
490 ~ 675 km
185 km
2.0
Total
20°~55°
185 ~ 675 km
490 km
5.2

19. Uniqueness of K-5 COSI for SSR
Repeat Cycle / Revolutions
Image Coverage (C)
Adjacent Pass Distance (at equator) (A)
Number of pass (N>2 for SSR)
ERS-1/2
35 days
500 rev.
100 km
80 km
1.25
RADARSAT-1
24 days
343 rev.
500 km
116 km
4.3
TerraSAR-X
11 days
167 rev.
Strip, Scan: 295km Spot: 480 km
240 km
1.2 for Strip and Scan,
2 for Spot
COSMO-SkyMed
16 days
237 rev.
Similar to COSI (?)
170 km
(?)
KOMPSAT-5 COSI
28 days
421 rev. km
95 km

20. Uniqueness of COSI for SSR
Radarsat-1 has been unique for SSR
Limited SSR availability of TerraSAR-X and COSMO-SkyMed unless significant satellite maneuvering
SSR will be valuable before the widespread of single-pass interferometers (e.g., TanDEM-X).
KOMPSAT-5 COSI is dedicated to SSR.

21. Radargrammetry At Equator

22. K5 Orbit Geometry for Radargrammetry At Equator
z (up)
K5 Orbit Geometry for Radargrammetry
At Equator
Left Look
Right Look
R: Earth radius
H: Altitude of satellite
Xg: Ground distance of adjacent pass
n: Pass number from nadir
x: Image location from nadir to east
|x|<Xg/2
θi: Incidence angle
Nominal: 20° < θi < 45 °
Extended: 45 ° < θi < 55 °
θl : Look angle
Rg: Ground range
Nominal: 185 km < Rg < 490 km
Extended: 590 km < Rg < 675 km
Rs: Ground range -1
n =0 1 -2 2 3 4
Satellite Pass θi θl
H = 550Km
Earth Surface
(Equatorial plane) x
Xg =95 km
at equator
East
R = 6378Km δ
Earth Center

23. Incidence angle as a function of x (position from Nadir)

24. Radargrammetric Geometry (x = -47.5 km)
z (up)
Radargrammetric Geometry (x = km)
Left Look
Right Look
Nominal Mode
Extended Mode -2 -1
n=0 1 2 3 4 5 6 7 8
Xa=95 km
Altitude
H = 550Km
x = km
x (east)
-47.5
+47.5

25. Radargrammetric Geometry (x = 0 km)
z (up)
Radargrammetric Geometry (x = 0 km)
Left Look
Right Look
Nominal Mode
Extended Mode -2 -1
n=0 1 2 3 4 5 6 7 8
Xa=95 km
Altitude
H = 550Km
x=0 km
x (east)
-47.5
+47.5

26. Radargrammetric Geometry (x = +47.5 km)
z (up)
Radargrammetric Geometry (x = km)
Left Look
Right Look
Nominal Mode
Extended Mode -2 -1
n=0 1 2 3 4 5 6 7 8
Xa=95 km
Altitude
H = 550Km
x=+47.5 km
x (east)
-47.5
+47.5

27. Height Sensitivity of Parallax

28. Height Sensitivity of Parallax
5-3 and 3-2 pairs are recommended with height sensitivity of

29. Days of SSR Orbits
2nd
Pass
1st 2 3 4 5 6 7 28 27 26 25 24 23 1

30. Radargrammetry at Mid-Latitude (Daejeon, Korea)

31. KOMPSAT-5 Orbits near Daejeon, Korea
Elevation angle: degree

32. Elevation Angles
5 orbits have 20°- 45°of incidence angles for nominal imaging mode (descending orbits only)

33. Height sensitivity of parallax at Daejeon, Korea
Radargrammetry Pair :
5-4, 7-5, 8-5
 θ₂(n)
θ₁(n)
22.92°
(4)
29.05°
(5)
34.46°
(6)
39.14°
(7)
43.16°
(8)
0.00
-0.56
-0.91
-1.14
-1.30
0.56
-0.34
-0.57
-0.73
0.91
0.34
-0.23
-0.39
1.14
0.57
0.23
-0.16
1.30
0.73
0.39
0.16

34. Orbits near Sejong Station, Antarctica

35. Elevation Angles at Sejong Station
12 orbits have 20°- 45°of incidence angles for nominal imaging mode (descending orbits only)

36. Height sensitivity of parallax at Sejong Station, Antarctica
19.97°
(6)
23.17°
(7)
26.08°
(8)
29.03°
(9)
31.79°
(10)
34.36°
(11)
36.69°
(12)
38.91°
(13)
40.93°
(14)
42.83°
(15)
44.58°
(16)
0.00
-0.42 
-0.71 
-0.95 
-1.14 
-1.29
-1.41
-1.51
-1.60
-1.67
-1.74
0.42
-0.29 
-0.53 
-0.72
-0.87
-0.99
-1.10
-1.18
-1.26
-1.32
0.71
0.29
-0.24
-0.43
-0.58
-0.70
-0.80
-0.89
-0.96
-1.03
0.95
0.53
0.24
-0.19
-0.34
-0.46
-0.56
-0.65
-0.79
1.14
0.72
0.43
0.19
-0.15
-0.27
-0.37
-0.53
-0.60
1.29
0.87
0.58
0.34
0.15
-0.12
-0.22
-0.31
-0.38
-0.45
1.41
0.99
0.70
0.46
0.27
0.12
-0.10
-0.26
-0.33
1.51
1.10
0.80
0.56
0.37
0.22
0.10
-0.09
-0.16
1.60
1.18
0.89
0.65
0.31
0.09
-0.07
-0.14
1.67
1.26
0.96
0.38
0.26
0.16
0.07
-0.06
1.74 
1.32
1.03
0.79
0.60
0.45
0.33
0.14
0.06

37. Conclusions
The orbit and imaging modes of KOMPSAT-5 COSI is dedicated to radargrammetry.
Orbit pairs for Radargrammetry (Height sensitivity of , Descending only)
Equator: two pairs
Mid-Latitude: Three pairs
Height resolution: Ten Pairs
Wider selection of pairs are theoretically provided.
Combination of ASC/DES, and L/R-looking will provide more opportunity.
Note that all calculations are true at equator. Further analysis is necessary for global configuration.
TerraSAR-X and COSMO-SkyMed data may provide tests of high-resolution examples, but not so versatile as KOMPSAT-5 COSI.