Phase-unwrapping algorithm for the measurement of three-dimensional object shapes

Zhao, Hong; Chen, Wenyi; Tan, Yushan

doi:10.1364/ao.33.004497

Cited by 212 publications

(90 citation statements)

References 6 publications

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“…Due to the complex nature of object surface shape and various unwanted noises inherent to the projection and acquisition of fringe patterns, phase unwrapping is a challenging task. Many approaches have been studied and employed such as spatial (4)(5)(6)(7) and temporal (8)(9)(10)(11)(12)(13). Spatial phase unwrapping approaches assume a continuity of scanned surfaces and likely fail in regions with depth discontinuities (step edges) (10).…”

Section: Introductionmentioning

confidence: 99%

Recovery of absolute phases for the fringe patterns of three selected wavelengths with improved anti-error capability

Long

Zhang

et al. 2016

Journal of Modern Optics

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In a recent published work, we proposed a technique to recover the absolute phase maps of fringe patterns with two selected fringe wavelengths. To achieve higher anti-error capability, the proposed method requires employing the fringe patterns with longer wavelengths; however, longer wavelength may lead to the degradation of the signal-to-noise ratio (SNR) in the surface measurement. In this paper, we propose a new approach to unwrap the phase maps from their wrapped versions based on the use of fringes with three different wavelengths which is characterized by improved anti-error capability and SNR. Therefore, while the previous method works on the two-phase maps obtained from six-step phase-shifting profilometry (PSP) (thus 12 fringe patterns are needed), the proposed technique performs very well on three-phase maps from three steps PSP, requiring only nine fringe patterns and hence more efficient. Moreover, the advantages of the two-wavelength method in simple implementation and flexibility in the use of fringe patterns are also reserved. Theoretical analysis and experiment results are presented to confirm the effectiveness of the proposed method. Recovery of absolute phases for the fringe patterns of three selected wavelengths with improved anti-error capabilityIn a recent published work we proposed a technique to recover the absolute phase maps of fringe patterns with two selected fringe wavelengths. To achieve higher anti-error capability, the proposed method requires employing the fringe patterns with longer wavelengths; however, longer wavelength may lead to the degradation of the signal-to-noise ratio (SNR) in the surface measurement. In this paper, we propose a new approach to unwrap the phase maps from their wrapped versions based on the use of fringes with three different wavelengths which is characterized by improved anti-error capability and SNR. Therefore, while the previous method works on the two phase maps obtained from six-step PSP (thus 12 fringe patterns are needed), the proposed technique performs very well on three phase maps from three steps PSP, requiring only 9 fringe patterns and hence more efficient.Moreover, the advantages of the two-wavelength method in simple implementation and flexibility in the use of fringe patterns are also reserved. Theoretical analysis and experiment results are presented to confirm the effectiveness of the proposed method.

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Section: Introductionmentioning

confidence: 99%

Recovery of absolute phases for the fringe patterns of three selected wavelengths with improved anti-error capability

Long

Zhang

et al. 2016

Journal of Modern Optics

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“…Zhao et al [7] used two phase images with different precision in unwrapping. Considering the numerous images required in Zhao's method, Li et al [8] proposed two-frequency grating profilometry, which entails only one grating instead of changing gratings with different equivalent wavelengths.…”

Section: Introductionmentioning

confidence: 99%

Stair phase-coding fringe plus phase-shifting used in 3D measuring profilometry

Zeng

et al. 2016

J. Eur. Opt. Soc.-Rapid Publ.

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As the number of codewords adopted in phase-coding fringes increases, the solution of fringe orders leads to many mistakes. Consequently, errors of the unwrapped phase occur. Thus, increasing the codeword approach in a phase-coding fringe remains a challenge. In this paper, a modified stair phase-coding fringe is designed, and a new phase unwrapping algorithm based on shifting fringe order is presented. The main idea of this method is that the width ratio between the sinusoidal fringe and each stair phase of phase-coding fringe is set to 1: n. The fringe order retrieved from the phase-coding fringe can be multiplied by the shift itself, thereby assisting phase unwrapping. This method adopts fewer codewords to replace the usual large number. As such, the approach gains two merits. One is that it guarantees a high measurement accuracy. The other is that it allows the measurement of isolated objects with complicated shapes. The experiments demonstrate that the proposed method is simple but effective.

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“…There are absolute phase techniques that can solve this problem, such as two-wavelength [2,3], multiwavelength [4,5], temporal phase-unwrapping [6], and gray-coding phase-shifting [7] methods. Among these methods, the gray-coding phase-shifting technique is one of the better methods by designing a unique codeword assigned to each 2π phase-change period.…”

mentioning

confidence: 99%