Polarimetric Scattering Model for Multilayered Vegetation in Tropical Forest

DISCLAIMER This document describes work undertaken as part of a programme of study at the Faculty of Geo-Information Science and Earth Observation of the University of Twente. All views and opinions expressed therein remain the sole responsibility of the author, and do not necessarily represent those of the Faculty. Dedicated to my loving mom and dad i ABSTRACT This research concentrates on understanding and analyzing polarization orientation angle shift and its influence in Freeman-II model based decomposition of fully-polarimetric synthetic aperture radar data. The radar transmits and receives backscatter information from Earth objects with respect to different polarizations. These backscatter responses are assumed to have polarization information from different scattering mechanism. Covariance matrix is the sum of these different scattering mechanisms. The random orientation of objects produces a shift in polarization orientation angle which leads to miscalculation of power in different polarization and there by covariance matrix. The circular polarization method of calculating orientation angle shift utilize coherency matrix. Similarity transformation matrix has been used to convert covariance matrix into coherency matrix for application of this method. The calculated orientation shift angles were used in unitary rotation matrix for the shift compensation. This compensation results in reduction in volume scattering power and increase in double bounce power with equal amounts and invariant surface return power in covariance matrix. The equal amount of reduction and increase in power leads to unchanged total power after compensation. Freeman-II decomposition techniques utilize covariance matrix to model the information from different scatter and it preserve total power. This decomposition technique assumes polarimetric backscatter response contains information from canopy scatter as volume scattering, double bounce and surface scattering. With the help of three different components it models these responses. The reduction in volume scattering power of covariance matrix leads to reduction in modelled contribution from canopy return and increase in surface return power in different amounts. The compensation of polarization orientation angle shift takes the total modelled power close to total power of covariance matrix. ALOS PALSAR fully-polarimetric data was used for this purpose. The data supply format was single look complex and it was used to generate Multilook images. The influence of noise in Multilook images was analyzed using statistical method. ii ACKNOWLEDGEMENTS First and foremost, I thank God the almighty who provided me good heath and knowledge to work for this thesis. I am extremely thankful to my IIRS supervisor, Mr. Shashi Kumar who …