Quality-guided phase unwrapping technique: comparison of quality maps and guiding strategies

School of Computer Engineering, Nanyang Technological University, Singapore.
Applied Optics (Impact Factor: 1.78). 11/2011; 50(33):6214-24. DOI: 10.1364/AO.50.006214
Source: PubMed


Quality-guided phase unwrapping is a widely used technique with different quality definitions and guiding strategies reported. It is thus necessary to do a detailed comparison of these approaches to choose the optimal quality map and guiding strategy. For quality maps, in the presence of noise, transform-based methods are found to be the best choice. However in the presence of discontinuities, phase unwrapping is itself unresolved and hence quality-guided phase unwrapping is not sufficient. For guiding strategies, classical, two-section, and stack-chain guiding strategies are chosen for comparison. If accuracy is the foremost criterion then the classical guiding strategy with a data structure of indexed interwoven linked list is best. If speed is of essence then the stack-chain guiding strategy is the one to use.

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Available from: Lei HUANG, Jan 07, 2015
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    • "The phase unwrapping process [1] [2] [3] [4] [5] [6] is an important stage for interferometric data processing, Synthetic Aperture Radar interferometry (SAR) [7] [8] [9] [10] [11] [12] [13] [14], Magnetic Resonance Imaging (MRI) [15], profilometry by fringe pattern projection [16], to mention just some applications . There are different approaches for phase unwrapping algorithms; some reviews on the topic are reported in [17] [18] [19] [20] and references therein. "
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    ABSTRACT: A main challenge associated with 3-dimentional fringe pattern profilometry (3D-FPP) systems is the unwrapping of phase maps resulted from complex object surface shapes with both robustness and speed guaranteed. In this paper we propose a new quality-guided phase unwrapping algorithm. In contrast to the conventional quality-guided methods, we classify pixels on wrapped phase map into two types by detecting edge pixels on object image: high quality (HQ) pixels corresponding to smooth phase changes and low quality (LQ) ones to rough phase changes. In order to improve the computational efficiency, these two types of pixels are unwrapped by means of different approaches. That is, the HQ pixels are unwrapped by a simple path following algorithm and the LQ ones are recovered by conventional flood-fill algorithm. Experiments show that the proposed approach is able to unwrap complex phase maps with the similar accuracy performance as and much higher speed than the conventional quality-guided algorithm.
    Computer Vision and Pattern Recognition Workshops (CVPRW), 2012 IEEE Computer Society Conference on; 06/2012
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    ABSTRACT: The regularized phase tracker (RPT) is one of the most powerful approaches for demodulation of a single fringe pattern. However, two disadvantages limit the applications of the RPT in practice. One is the necessity of a normalized fringe pattern as input and the other is the sensitivity to critical points. To overcome these two disadvantages, a generalized regularized phase tracker (GRPT) is presented. The GRPT is characterized by two novel improvements. First, a general local fringe model that includes a linear background, a linear modulation and a quadratic phase is adopted in the proposed enhanced cost function. Second, the number of iterations in the optimization process is proposed as a comprehensive measure of fringe quality and used to guide the demodulation path. With these two improvements, the GRPT can directly demodulate a single fringe pattern without any pre-processing and post-processing and successfully get rid of the problem of the sensitivity to critical points. Simulation and experimental results are presented to demonstrate the effectiveness and robustness of the GRPT.
    Optics Express 05/2012; 20(11):12579-92. DOI:10.1364/OE.20.012579 · 3.49 Impact Factor
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