The document summarizes research using TanDEM-X Pol-InSAR data to estimate agricultural parameters. It presents methods for estimating parameters like soil moisture, roughness, and vegetation height from different scattering mechanisms. Initial dual-pol TanDEM-X data takes show potential for crop height monitoring but challenges due to low kz and short vegetation heights. Future very short baseline TanDEM-X acquisitions could help address this for growing crops.

1. TanDEM-X: Pol-InSAR over Agricultural Areas
*Irena Hajnsek, Kostas Papathanassiou, Florian Kugler
Microwaves and Radar Institute, DLR Oberpfaffenhofen, Germany
* Institute of Environmental Engineering, ETH Zurich, Switzerland
IGARSS’11, Vancouver

2. Agricultural Parameter Estimation: Current Research Status
Scat Developed Research
Physical Products Observables
Mechanisms Methods Status
Bare surface X-Bragg Soil Moisture Content PolSAR medium
(surface Soil Roughness @ longer l mature
scattering, Soil Penetration Depth
dihedral scat.)
Vegetated Decomposition Topography PolSAR low
surface Theorems Soil Moisture Content Pol-InSAR mature
(surface, Soil Roughness D-InSAR
dihedral,
@ longer l
volume scat.)
Vegetation RVoGM Vegetation Height PolSAR low
volume OVoGM Vegetation Extinction InSAR mature
(volume, PCT Vegetation Structure Pol-InSAR
dihedral scat.) Vegetation Biomass @ shorter l
Slide 2

3. Agricultural Parameter Estimation: Current Research Status
Scat Developed Research
Physical Products Observables
Mechanisms Methods Status
Bare surface X-Bragg Soil Moisture Content PolSAR medium
(surface Soil Roughness @ longer l mature
scattering, Soil Penetration Depth
dihedral scat.)
Vegetated Decomposition Topography PolSAR low
surface Theorems Soil Moisture Content Pol-InSAR mature
(surface, Soil Roughness D-InSAR
dihedral,
@ longer l
volume scat.)
Vegetation RVoGM Vegetation Height PolSAR low
volume OVoGM Vegetation Extinction InSAR mature
(volume, PCT Vegetation Structure Pol-InSAR
dihedral scat.) Vegetation Biomass @ shorter l
Slide 3

4. Agricultural Parameter Estimation: Current Research Status
Scat Developed Research
Physical Products Observables
Mechanisms Methods Status
Bare surface X-Bragg Soil Moisture Content PolSAR medium
(surface Soil Roughness @ longer l mature
scattering, Soil Penetration Depth
dihedral scat.)
Vegetated Decomposition Topography PolSAR low
surface Theorems Soil Moisture Content Pol-InSAR mature
(surface, Soil Roughness D-InSAR
dihedral,
@ longer l
volume scat.)
Vegetation RVoGM Vegetation Height PolSAR low
volume OVoGM Vegetation Extinction InSAR mature
(volume, PCT Vegetation Structure Pol-InSAR
dihedral scat.) Vegetation Biomass @ shorter l
Slide 4

5. Agricultural Parameter Estimation: Current Research Status
Scat Developed Research
Physical Products Observables
Mechanisms Methods Status
Bare surface X-Bragg Soil Moisture Content PolSAR medium
(surface Soil Roughness @ longer l mature
scattering, Soil Penetration Depth
dihedral scat.)
Vegetated Decomposition Topography PolSAR low
surface Theorems Soil Moisture Content Pol-InSAR mature
(surface, Soil Roughness D-InSAR
dihedral,
@ longer l
volume scat.)
Vegetation RVoGM Vegetation Height PolSAR low
volume OVoGM Vegetation Extinction InSAR mature
(volume, PCT Vegetation Structure Pol-InSAR
dihedral scat.) Vegetation Biomass @ shorter l
Slide 5

6. Kz Range for Agricultural Applications
Adapted to TanDEM-X system configuration For a crop height of 1-2.5m a kz between
Incidence angle fixed for 30 degree 2-3 provides the best sensitivity
Slide 6

7. Kz Range Translated into Baseline (TanDEM-X Configuration)
For a kz of 2-3 baselines from 2-3km would be ideal corresponding to a
height of ambiguity of ~ 2-3m.
Slide 7

8. Agricultural Test Site Wallerfing (North of Munich)
1 km
Acqu. Dates Comments / Ground Campaign HOA/baseline/kz
maize
12.04 acquired, no on-site measurements 38m/133m/0.047
23.04 acquired, no on-sitewinter wheat
measurements --
rape
04.05 acquired, on-site measurements 33m/153m/0.041
15.05 acquired, on-site measurements 32m/160m/0.039
26.05 acquired, on-site measurements 30m/167m/0.038
06.06 corrupted --
17.06 acquired, no on-site measurements --
28.06 acquired, on-site measurements --
09.07 planed --
20.07 planed --
31.07 planed --
11.08 planed --
Slide 8
22.08 planed --

9. Site Overview – Phenology 04. May 2011
(blue marks: soil moisture; yellow marks: vegetation & partly soil moisture)
maize winter wheat rape seed
height = 0 cm height = 26 cm height = 131 cm
Slide 9

10. Site overview – Phenology 15./26. May 2011
maize winter wheat rape seed
height = 5 cm height = 36 cm height = 126 cm
height = 25 cm height = 51 cm height = 133
cm
Slide 10

11. Meteo Data: Daily Precipitation 01.04.-31.05.2011
© StMELF Agrarmeteo
Temperature and Precipitation
25 30
25
20
precipitation [mm]
temperature [°C]
20
15 RAINSUM
TA200AVG
15
TS005AVG
10
10
5
5 Data take
0 0
11
11
11
11
11
11
11
11
11
4/
4/
4/
4/
4/
5/
5/
5/
5/
/0
/0
/0
/0
/0
/0
/0
/0
/0
01
08
15
22
29
06
13
20
27
date
Slide 11

12. TanDEM-X: Dual-Pol InSAR: First Bistatic Data Takes
Date: 12/04
Year: 2011
Pol: HH & VV
Stripmap Mode
Slide 12
Test Site: Wallerfing, Germany

13. TanDEM-X: Dual-Pol InSAR: First Bistatic Data Takes
Date: 04/05
Year: 2011
Pol: HH & VV
Stripmap Mode
Slide 13
Test Site: Wallerfing, Germany

14. TanDEM-X: Dual-Pol InSAR: First Bistatic Data Takes
Date: 15/05
Year: 2011
Pol: HH & VV
Stripmap Mode
Slide 14
Test Site: Wallerfing, Germany

15. TanDEM-X: Dual-Pol InSAR: First Bistatic Data Takes
Date: 26/05
Year: 2011
Pol: HH & VV
Stripmap Mode
Slide 15
Test Site: Wallerfing, Germany

16. 2-Dim Polarimetric
Scattering Entropy
12.04.2011 04.05.2011
15.05.2011 26.05.2011
Slide 16

17. 2-Dim Polarimetric
Scattering Angle
12.04.2011 04.05.2011
15.05.2011 26.05.2011
α=90°
α=45°
α=0°
Slide 17

18. SNR correction
Interferometric coherence VV-Pol 04/05/2011
Test Site: Wallerfing, Germany
Slide 18

19. SNR correction Coherence VV 4th May 2011
04/05/2011
HH VV Terra SAR-X
NESZ Polynomials (from xml files)
HH VV TanDEM-X
Test Site: Wallerfing, Germany
Slide 19

20. Pol-InSAR SNR Correction
Interferometric coherence VV-Pol Interferometric coherence VV-Pol
before SNR correction after SNR correction
04.05.2011 Test Site: Wallerfing, Germany
Slide 20

21. Pol-InSAR SNR Correction
Interferometric coherence HH-Pol Interferometric coherence HH-Pol
before SNR correction after SNR correction
04.05.2011 Test Site: Wallerfing, Germany
Slide 21

22. VV Coherence
12.04.2011 04.05.2011
15.05.2011 26.05.2011
Slide 22

23. HH Coherence
12.04.2011 04.05.2011
15.05.2011 26.05.2011
Slide 23

24. Max Coherence
12.04.2011 04.05.2011
15.05.2011 26.05.2011
Slide 24

25. Min Coherence
12.04.2011 04.05.2011
15.05.2011 26.05.2011
Slide 25

26. Pol-InSAR SNR Masking
Interferometric coherence Max Interferometric coherence Min
04.05.2011 Test Site: Wallerfing, Germany
Slide 26

27. Pol-InSAR SNR Masking
Interferometric coherence Max Interferometric coherence Min
04.05.2011 Test Site: Wallerfing, Germany
Slide 27

28. Pol-InSAR SNR Masking
12.04.2011 04.05.2011 15.05.2011 26.05.2011
Slide 28

29. InSAR Coherence VV-pol: Zoom for Field Selection
12/04
04/05
15/05
26/05
Slide 29

30. Statistics of the InSAR Coherence (3 Fields)
Interferometric coherence measured as a mean over the entire field
Red: rape,
Green: corn,
Blue: wheat
Red: rape,
Green: corn,
Blue: wheat
Slide 30

31. Dual Pol-InSAR: Maximum Phase Difference Estimation
  
Interferometric Coherence: ~( w i , w i ) at polarisation w i
γ
 
 
~( w , w )   w i [Ω]w i 
γ i i    
 w i [T11]w i  w i [T22 ]w i 
~     
Coherence Region: γ( w i , w i )  w i  awHH  bw VV a,b  C
 
~( w , w )
γ max max
  Max. Phase diff. between polarisations
~( w , w )
γ min min
Slide 31

32. Dual Pol-InSAR: Max Height Difference
12.04.2011 15.05.2011
04.05.2011 26.05.2011
Slide 32

33. Statistics of the Max Phase Difference & Height Difference
Red: rape Red: rape
Green: corn Green: corn
Blue: wheat Blue: wheat
Main problem:
Too low kz
Very short vegetation
Solution:
Special 3-4 months TanDEM-X phase for growing crops
(hopefully in the third year)
Slide 33

34. First Pol-InSAR
Data Takes
Dual-Pol HH-VV Spotlight
Test Site Location: Russia
InSAR Mode: Monostatic
Temporal Baseline: 3sec
Spatial Baseline (┴): 275m
Slide 34

35. Pol-InSAR HH VV
Amplitude Images
Interferometric HH-HH VV-VV
Coherence
Slide 35

36. Pol-InSAR
Kz: 0.24
HOA: 26
Baseline: 252m
AOI: 39°
Max height difference
0 1 2 [m] 3
Slide 36