Fig. 1. EMD decomposition results of one-dimensional signal. (a) Original signal with noise; (b) imf1 component; (c) imf2 component; (d) imf3 component; (e) imf4 component; (f) residual trend component

Fig. 2. Schematics of multidirectional decomposition of image. (a) Horizontal direction; (b) left diagonal direction; (c) vertical direction; (d) right diagonal direction

Fig. 3. Scattergram of PSC points after initial selection

Fig. 4. Phase comparison of differential interferograms before and after filtering. (a) Original interferogram with noise; (b) interferogram denoised by EMD; (c) interferogram denoised by improved EMD

Fig. 5. Phase of PSC points before and after filtering. (a) Before filtering; (b) after filtering

Fig. 6. Distribution histogram of PSC points

Fig. 7. Probability density function p(γg) of γg

Fig. 8. Final scatter gram of PS points in study area

Fig. 9. Scattergrams of PS points detected by different methods. (a) Amplitude deviation index threshold method; (b) coherence coefficient threshold method; (c) phase deviation index threshold method; (d) EMD method

Fig. 10. Scattergrams of PS points detected by different methods. (a) Amplitude deviation index threshold method; (b) coherence coefficient threshold method; (c) phase deviation index threshold method; (d) EMD method; (e) proposed method