1. Polarimetric Calibration Using Distributed Odd-bounce Targets Jiong CHEN 1, 3* Motoyuki SATO 2 Jian YANG 3 1. Graduate School of Environmental Studies, Tohoku University, Japan 2. Center for Northeast Asian Studies, Tohoku University, Japan 3. Department of Electronic Engineering, Tsinghua University, China *E-mail: jiongc@cneas.tohoku.ac.jpjiongc@cneas.tohoku.ac.jp 07/2011

2. After calibration Retrieval of soil moisture Estimation of biomass Classification of terrainMonitoring of flood Introduction ALOS/PALSAR Y. Oh 1992H. Yamada, et.al. 2001 2/13

3. Polarimetric Calibration Polarimetric SAR Model for Calibration Basic Assumptions Conventional Methods 1. Reciprocity 2.Statistical symmetry on distributed targets 3. Known Calibrators Van ZylQueganKimura Assumption 1,2,3Assumption 1,2Assumption 1, Slight 2 3/13

4. Motivations The deployment of trihedral is inconvenient –For low frequency system, the size should be relatively large –To implement calibration ubiquitously The assumption is not always valid –Only valid for statistically symmetric distributed targets –Small value will cause large bias in the calibration results Develop a calibration method without the trihedral or the assumption 4/13

5. Basic Scheme and Assumptions Conventional method : Trihedral Proposed method : Use the statistic information of odd- bounce targets Robust estimator using odd- bounce targets Assume cross-talk to be small Advantage : 1. Standard trihedral calibrator is not needed 2. The assumption is not needed 5/13

6. Decomposition of Distortion Matrix Channel Imbalance Non-reciprocal effect Cross-talk 6/13

7. Selection of Odd-bounce Targets Statistical information of odd-bounce targets Trihedral 7/13 Typical odd-bounce targets Statistical property AmplitudePhase Flight direction Optical image, captured from Google Earth

8. Removal of Channel Imbalance 8/13

9. Robust Estimator of Non-reciprocal Effect Odd-bounce targets : Good for the estimation of Distribution of on odd-bounce targets : Laplace 9/13 Similarity Parameters The robust estimate Fitting Result Laplace distribution with different parameters

10. Estimation of Cross-talk 10/13 On Odd-bounce targets Assuming Estimated Distortion Matrix

11. Discussion on Results Calibration result 11/13 New distortion matrices JAXA Standard distortion matrices Co-polarized signature on trihedral Uncalibrated JAXA standard calibrated result New calibrated resultTheoretical result

12. Removal of Faraday Rotation Sendai 090604 Sendai 070414 Alaska 070729 12/13

13. A practical calibration scheme based on distributed odd-bounce targets is proposed –The distortion matrix is decomposed firstly –The statistical information of odd-bounce targets is used as alternative to trihedral –A robust estimator based on odd-bounce targets is derived to estimate the non-reciprocal effect –It can be used as a rough calibration method without the special deployment of trihedral calibrators, nor the un-correlation consumption Conclusion 13/13