Investigation Of Wheat Vegetation Height Retrieval Of Polarimetric Interferometry SAR

Polarimetric interferometry SAR is a new technique that integrates polarization SAR and interferometry SAR effectively. It comprehensives the all advantages of interferometry SAR and polarization SAR.It not only reflects the physical characteristics but also obtains spatial distribution properties of targets. Polarimetric interferometry SAR can. obviously improve the signal-to-noise ratio of interferometry phase and the parameter inversion precision of ground height. For the complicated scene that having many different goals, polarimetric interferometry SAR can separate the interferometry phase center of multiple scattering mechanism and extract different polarimetric interferometry phase by scattering matrix decomposition technique.So polarimetric interferometry SAR provides the possibility for measurement of the surface vegetation cover terrain and estimate vegetation height. It has great significance to monitor the ground resources and environmental protection.In this paper, we studied the basic theories of polarimetric interferometry SAR and inversion algorithms of ground vegetation height. This paper mainly work and innovation of are as follows:(1) We analysis the characteristics of the scattering mechanism for polarimetric interferometry SAR and their sensitivities for vegetation regional. Research the unconstrained condition optimal polarization interference coherence coefficient algorithm,it can obtain the separation of scattering mechanisms on surface target.(2) Research polarimetric interferometric SAR scattering phase center estimation deeply. This dissertation intensively studies the scattering phase estimation based on ESPRIT algorithm. The simulated data created by polsarpro are used to validate the algorithm. The results demonstrate that the scattering phase estimation based on ESPRIT algorithm can estimate the phase corresponding to the top of the canopy, but can not accurately estimate the phase corresponding to the ground. Because of the disadvantages of the scattering phase corresponding to the ground estimation, a modified algorithm combined with the optimal polarization interference coherence coefficient algorithm based on ESPRIT is proposed. The simulated experiment indicates that this modified algorithm can improve retrieval accuracy.Then,we study Freeman polarimetric interferometry covariance matrix decomposition algorithm, the scattering phase estimation based on Freeman-polarimetric interferometry covariance matrix decomposition algorithm can effectively estimate the ground phase but can not accurately estimate the phase corresponding to the top of the canopy.(3) By combing the advantages of the scattering phase estimation based on the modified ESPRIT algorithm and that of Freeman polarimetric interferometry covariance matrix decomposition algorithm, a joint algorithm is proposed. It can estimate vegetation height by taking the difference between the ground phase of Freeman-polarimetric interferometry covariance matrix decomposition algorithm and the top of the canopy phase of the modified algorithm based on ESPRIT. Finally, the experiment demonstrates that the joint algorithm can obtain the best accuracy and the smallest error compared with the above three algorithms.(4) We study some vegetation parameter inversion algorithms of double-baseline polarimetric interferometry SAR. The Cloude three stage method for vegetation height of single-baseline and dual-baseline inversion are simulated and compared using single baseline and dual baseline simulation data, respectively.The comparison result demonstrates that the three stage method for vegetation height of dual-baseline algorithm can obtain the better accuracy and the smaller error compared with the three stage method for vegetation height of single-baseline.