A Fractal Estimation Method to Reduce the Distortion in Phase Unwrapping Process

Andriyan Bayu SUKSMONO

IEICE TRANSACTIONS on Communications   Vol.E88-B    No.1    pp.364-371
Publication Date: 2005/01/01
Online ISSN: 
DOI: 10.1093/ietcom/e88-b.1.364
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Sensing
phase unwrapping,  1/f noise,  fractal geometry,  fractional Brownian motion,  FFT,  InSAR,  DEM,  

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Two-dimensional phase unwrapping (PU) process usually causes a noise-induced distortion in the geographical information of a wrapped phase image obtained by, for example, interferometric synthetic aperture radar (InSAR). This paper presents a novel method to reduce the phase-unwrapping distortion by being based on two-dimensional fractional Brownian motion (fBm) theory. The method incorporates fractal geometry estimation with conventional global-transform PU. For the spatial-frequency spectrum of an observed phase image, we estimate the fractal dimension by assuming an almost constant dimension over the image. Then, according to the estimation, we compensate the distorted spectrum of the tentatively computed global PU result. We obtain a better topographical map as the inverse Fourier transform of the compensated spectrum. It is demonstrated that the proposed method increases the signal-to-noise ratio of PU results for simulated data with various noise levels. Evaluations on an actual InSAR phase image also show that the method significantly improves the quality of the conventional global-transform PU result, in particular in its fine structure.