An improved stair phase encoding method for absolute phase retrieval

Zhou, Changli; Liu, Tongchuan; Si, Shuchun; Xu, Jianqiang; Liu, Yepeng; Lei, Zhenkun

doi:10.1016/j.optlaseng.2014.09.011

Cited by 56 publications

(11 citation statements)

References 13 publications

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“…Furthermore, color crosstalk and nonlinear color responding of imaging devices cannot be avoided, thus, the edge of color strips is difficult to identify and that will reduce the accuracy of phase extraction. Zhou [15] proposed an improved phase unwrapping method based on a stair phase coding method. Two groups of 4-step phase-shifting fringe patterns are put into different channels of RGB color fringe patterns.…”

Section: Introductionmentioning

confidence: 99%

A dual-frequency fringe projection three-dimensional shape measurement system using a DLP 3D projector

Dai

Yang

Liu

et al. 2017

Optics Communications

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A dual-frequency fringe projection system for three-dimensional (3D) surface shape measurement is proposed in this paper. The system includes two cameras, a DLP 3D projector, and a liquid crystal (LC) shutter glasses. The phase information related to the object height is obtained from the dual-frequency temporal method with 3-step phase-shifting algorithm. By using the DLP 3D projector and LC shutter glasses, 3-step phase-shifting high-frequency and low-frequency fringe patterns are captured only 3 times by the two cameras synchronously. The technique of image registration is applied to low-frequency fringe patterns to guarantee the accuracy of low-frequency phase for high-frequency phase unwrapping. Using the equi-phase coordinate method based on two reference planes, the phase-to-height conversion and non-sinusoidal errors reduction are carried out in one go without any extra operation or measurement time. Experimental results demonstrate that the proposed method effectively improves the measuring speed, and it is valid for measuring surface shapes with multi-steps or discontinuities.

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Section: Introductionmentioning

confidence: 99%

A dual-frequency fringe projection three-dimensional shape measurement system using a DLP 3D projector

Dai

Yang

Liu

et al. 2017

Optics Communications

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“…Different from the method proposed by Wang, Zheng et al [18] introduced a technique wherein two sets of phase-coding fringes are projected to address the difficulty in judging the fringe order. Basing from Zheng's foundation, Zhou et al [19] developed a color fringe coding method to hasten the measurement speed. However, this technique was required to handle the color crosstalk.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, two issues must be clarified. First, basing from Zhou's method [19] shown in Fig. 1a, we design a modified stair phase-coding fringe that exactly retrieves the codewords.…”

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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“…The binary defocusing technique [45], [77] is an effective and widely used method to reduce the projection time for each pattern. To reduce the number of the required patterns for different TPU methods, many new methods, such as ternary gray code phase unwrapping [78], two-plus-one phase-shifting algorithm [79]- [81], geometry [81], [82] and continuity [83], [84] constrained SPU, have been proposed.…”

Section: Temporal Phase Unwrapping (Tpu)mentioning

confidence: 99%

“…In FPP, geometry/continuity constrained phase unwrapping is combined with the TPU methods to enhance the accuracy [81], [82] or reduce the required patterns [83], [84]. The main idea of the geometry/continuity constrained phase unwrapping is illustrated in Fig.…”

Section: Geometry/continuity Constrained Spumentioning

confidence: 99%

Temporal phase unwrapping towards high-accuracy and high-speed fringe projection profilometry

He¹

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An improved stair phase encoding method for absolute phase retrieval

Cited by 56 publications

References 13 publications

A dual-frequency fringe projection three-dimensional shape measurement system using a DLP 3D projector

A dual-frequency fringe projection three-dimensional shape measurement system using a DLP 3D projector

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

Temporal phase unwrapping towards high-accuracy and high-speed fringe projection profilometry

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