title: Improved Goldstein Interferogram Filter Based on Local Fringe Frequency Estimation.
abstract: The quality of an interferogram, which is limited by various phase noise, will greatly affect the further processes of InSAR, such as phase unwrapping. Interferometric SAR (InSAR) geophysical measurements', such as height or displacement, phase filtering is therefore an essential step. In this work, an improved Goldstein interferogram filter is proposed to suppress the phase noise while preserving the fringe edges. First, the proposed adaptive filter step, performed before frequency estimation, is employed to improve the estimation accuracy. Subsequently, to preserve the fringe characteristics, the estimated fringe frequency in each fixed filtering patch is removed from the original noisy phase. Then, the residual phase is smoothed based on the modified Goldstein filter with its parameter alpha dependent on both the coherence map and the residual phase frequency. Finally, the filtered residual phase and the removed fringe frequency are combined to generate the filtered interferogram, with the loss of signal minimized while reducing the noise level. The effectiveness of the proposed method is verified by experimental results based on both simulated and real data.
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. 18010127731@163.com.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Feng
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. xuhuaping@buaa.edu.cn.
authors.forename: Huaping
authors.initials: H
authors.lastname: Xu
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. wuzheming001@126.com.
authors.forename: Zhefeng
authors.initials: Z
authors.lastname: Wu
authors.affiliation: School of Electronic and Information Engineering, Beihang University, Beijing 100191, China. yyngc@126.com.
authors.forename: Yanan
authors.initials: Y
authors.lastname: You
authors.affiliation: Electronic and Electrical Engineering Department, University of Sheffield, Sheffield S1 3JD, UK. w.liu@sheffield.ac.uk.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: Nanjing Research Institute of Electronics Technology, Nanjing 210039, China. raymond2464@126.com.
authors.forename: Shiqi
authors.initials: S
authors.lastname: Ge
keywords: Goldstein interferogram filter; interferometric synthetic aperture radar (InSAR); local fringe frequency estimation