Spaceborne Polarimetric SAR Interferometry And Tomography Imaging

This paper analyzes several important problems in Spaceborne polarimetric interferometry and Tomography SAR,such as baseline estimation,the inclination displacement of top position of vertical line-shape object monitoring using improved DINSAR model,polarimetric interferometry SAR coherence optimization,the abrupt motion monitoring using differential tomography SAR imaging.For spaceborne INSAR,DINSAR,POLINSAR,POLDINSAR,TomoSAR and D-TomoSAR,we need to know the baseline between different acquisitions first.Consequently,this paper analyzes the problem of baseline estimation in Section II.After that,considering traditional DINSAR model can not be used to calculate the inclination displacement of vertical line-shape object due to the layover in the SAR image of the tower,this paper proposes the improved DINSAR model to monitor the inclination displacement of top position of vertical line-shape object in Section III.Full polarimetric information can be used to improve the DEM and ground surface deformation calculation accuracy based on POLINSAR and POLDINSAR techniques.For these two techniques,the first thing we need to do is to find the optimum polarization combination,this paper analyzes the problem of coherence optimization in Section IV.INSAR and DINSAR can not be used to obtain the DEM and ground surface deformation in layover areas,TomoSAR and D-TomoSAR can separate several scatters located in one layover pixel and obtain their locations and deformation.Especially for abrupt motion analyzation,it has not been reported.This paper analyzes the TomoSAR and D-TomoSAR algorithm at the case of abrupt motion in Section V.The main contributaions of this paper are as follows.(1)This paper proposes the baseline estimation method based on the interferogram fringes frequency under the constraint of the prior information of satellite orbit parameters.In the experiment,compared to the result processed by the software SARscape,the method based on the interferogram fringes frequency is not robust which would give the incorrect result.The accuracy of the method based on the satellite orbit parameters model is not high.The method proposed in this paper can obtain basically the same result compared to SARscape.(2)This paper proposes the improved DINSAR model to calculate the inclination displacement of top position of vertical line-shape object.This paper derives the relation equation between the inclination displacement of top position of vertical line-shape object and its corresponding differential phase.The implementing algorithm proposed in this paper can remove the top-bottom vertical height interferometry phase of vertical line-shape object just using the height geometry information itself.Then we use the residual differential interferometry phase after phase unwrapping to get the inclination displacement of top position of this vertical line-shape object.Atmospheric phase does not need to be considered in this improved DINSAR model because atmospheric phase at different positions of the vertical line-shape object will be offset between each other due to their relative close distance and its low-pass frequency quality along the spatial series pixels.Low-pass filter can be used to obtain a better calculation result for the inclination displacements of top position of vertical line-shape object in multi-temporal series images due to its low-pass frequency quality and the high-pass frequency quality of noise along the temporal series pixels.Power transmission tower is used for simulation as a kind of typical vertical line-shape object.The results demonstrates the effectiveness of the proposed method in this paper.(3)Coherence optimization in POLINSAR or POLDINSAR is a 4-D optimization problem.This paper proposes the method based on SNR optimum(SNR-OPT)which transforms the original 4-D optimization problem into two independent 2D optimization problems to solve separately.Moreover,we further transform this two independent 2D optimization problems into one 2D optimization problem and two independent 1D optimization problems to solve separately.It can improve the computation efficiency largely at a very small price in accuracy loss.(4)For abrupt motion of the scatterers monitoring using D-TomoSAR,we can compensate the acquisition which has the abrupt motion using a phase factor and then maximize the 3D Elevation-Linear motion-Amplitude of periodic motion spectrum,the corresponding phase factor after maximizing the 3D Elevation-Linear motion-Amplitude of periodic motion spectrum would be used to calculate the final abrupt motions of the scatterers.The simulation results demonstrate the proposed method can get accurate results which can meet the practical applications.Finally,this paper uses TomSAR imaging methods based on ESPRIT algorithm to calculate the height of the electric power transmission tower.TerraSAR-X data is used for experiment.Compared to the real measured data by the electric power company and the calculation result using the method based on geometry relation of the power transmission tower projected on the SAR image,the experimental results demonstrate the ESPRIT algorithm has a good accuracy.