Polarimetric Calibration of L-Band UAVSAR Data
- PDF / 1,403,739 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 88 Downloads / 198 Views
RESEARCH ARTICLE
Polarimetric Calibration of L-Band UAVSAR Data Arun Babu1
•
Shashi Kumar1 • Shefali Agrawal2
Received: 4 October 2020 / Accepted: 22 October 2020 Indian Society of Remote Sensing 2020
Abstract The polarimetric distortion in the PolSAR datasets causes the polarimetric decomposition and classification techniques to produce wrong outputs, which result in misinterpreting the scattering phenomenon and the ground targets. The most important polarimetric distortions in airborne PolSAR datasets are the channel imbalance and crosstalk. The minimization of these polarimetric distortions using polarimetric calibration techniques is very important to carry out the quantitative analysis using PolSAR data and time-series analysis and to compare the results between different sensors. The objective of this study was to implement the external polarimetric calibration of the L-band UAVSAR system using trihedral corner reflectors. The polarimetric distortion matrix (PDM) was formulated after considering the crosstalk and channel imbalance polarimetric distortions to derive the scattering matrix free from all kinds of polarimetric distortions from the observed scattering matrix. The channel imbalance between different polarization channels was estimated with the help of trihedral corner reflectors and homogeneously distributed targets. The crosstalk parameters were estimated by assuming the scattering reciprocity constraint, which is valid in the case of monostatic radars. The scattering matrix free from polarimetric distortions was derived from the PDM after estimating the polarimetric distortions. The polarimetric signatures and the coherency matrix behaviour of the trihedral corner reflectors were used to analyse the ground target characterization improvement after polarimetric calibration. Keywords UAVSAR Polarimetric calibration Trihedral corner reflectors Channel imbalance Crosstalk
Introduction The Quad-pol SAR data are useful in understanding the different scattering mechanisms happening on the Earth’s surface from different types of targets using the phase and amplitude information from the four-channel data with the help of different polarimetric decomposition and classification techniques (Ullmann et al. 2016). But the polarimetric distortions in the polarimetric SAR datasets cause the polarimetric decomposition and classification techniques to produce wrong outputs, which result in misinterpreting the scattering phenomenon and the ground targets (Jung and Park 2018). The most important of the
& Arun Babu [email protected] 1
Photogrammetry and Remote Sensing Department, Indian Institute of Remote Sensing, Dehradun, India
2
Geospatial Technology and Outreach Programme Group, Indian Institute of Remote Sensing, Dehradun, India
polarimetric distortions are the channel imbalance, crosstalk and Faraday rotation errors (Babu et al. 2019a). The channel imbalance between the different polarizations occurs mainly due to the gain mismatch between the power amplifiers used for horizontal a
Data Loading...
