SAR Interferogram Phase Filtering Using Wavelet Transform

The application of SAR Interferometry (InSAR) especially in Digital Elevation Modeling as well as deformation monitoring encounters problems due to noise in the interferogram phase. The noise is mainly caused by temporal and baseline decorrelation as well as changes in atmospheric conditions that makes the process of phase reconstruction difficult and reduces the accuracy. The quality of digital elevation models and displacement maps can be improved by filtering the interferometric phase. This paper reviews the methods of for noise reduction of interfermetric phase. It discusses a new algorithm based on wavelet transform which reduces the noise without reducing the spatial resolution or using any window over the interferogram. Comparing this algorithm with the other existing methods shows its strength in reducing the noise and preserving the signal. The effectiveness of the proposed filtering algorithm is tested by applying it to the InSAR results of the Bam earthquake. The results show that the filtering algorithm using wavelet transform is very successful in reducing noise in the interferogram.