A filtering method of InSAR interferogram based on Q-shift DT-CWT

After making a compare of three kinds of main filtering methods of InSAR interferogram, a filtering method based on Q-shift DT-CWT was developed in this paper. For this algorithm, the real and imagery parts of the original interferogram were transformed to complex wavelet field by Q-shift DT-CWT firstly. Then the wavelet coefficients were weighted by power or exponent function. Finally, the wavelet coefficients were transformed in space field by the inverse Q- shift DT-CWT, and then the phase filtered results can be calculated. Using the actual interferogram, weighting experiments of different transform methods such as FFT and DT-CWT were performed. The results show that the interferogram filtered by power weighting function is much better than that of exponent function, and compared with the FFT filtering method, DT-CWT weighting algorithm has great advantages in complex topographic areas. After filtering, the number of residues and mean of coherent coefficients in the interferogram have been become to 134 and 0.953697 respectively.