Modified five-step phase-shift algorithm for 3D profile measurement

Luo, Jian; Wang, Yu; Yang, Xu; Chen, Xiangcheng; Wu, Zihong

doi:10.1016/j.ijleo.2018.02.057

Cited by 13 publications

(6 citation statements)

References 27 publications

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“…Seen from equation ( 19), the abnormal shifting-phase errors occur at φ = π /4 + nπ , for ICM, where n is a nonnegative integer. And the wrapped phase errors of ICM decrease as the absolute value of the shifting-phase decreases according to equation (20). When the shifting-phase of ICM is 0 degree, the wrapped phase errors reach a minimum value.…”

Section: Error Models Of Icmmentioning

confidence: 99%

“…In general, the shifting-phase step between two successive phase shifting images is 2π /N. The typical fixed-step phase shifting methods have three-, four-and five-step phase shifting methods [18][19][20]. In contrast, the equal-step phase shifting method is independent of specific shifting-phase values but instead requires a consistent shifting-phase step between consecutive images, making it more adaptable and easier to implement.…”

Section: Introductionmentioning

confidence: 99%

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Comparative study of variant shifting-phase coding method based on noise error model

Wu,

Mu,

Cheng

et al. 2024

Meas. Sci. Technol.

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Phase shifting algorithm, which is well-known for its high-accuracy and high-resolution, plays a crucial role in fringe projection profilometry. A class of variant shifting-phase coding method (VSPCM) has been proposed for high-speed 3D measurement. The three kinds of VSPCM include the inner shifting-phase method (ISPM), the intensity-coded method (ICM) and the modified Carré algorithm (MCA). These methods project only four patterns avoiding the need for extra images, yet achieve accuracy comparable to the classical three-frequency heterodyne method. In VSPCM, the shifting-phase, as a key code-word for phase unwrapping, is encoded as a variable value. In practice, the noise and the encoding of shifting-phase have varying degrees of impact on the performance of these methods. But the coded ranges of the shifting-phase were previouly empirical values. Besides, there are no studies related to these factors, and also a lack of comparative researches on such methods. This paper compares three kinds of VSPCM for the first time. We derive the noise error models for shifting-phase and wrapped phase in three methods and examine the impact of variant shifting-phase on fringe orders and wrapped phase in these methods. We find that the abnormal shifting-phase errors predominantly cause fringe orders errors. Fortunately, median filtering can effectively handle shifting-phase errors to ensure successful phase unwrapping. To improve their accuracy, we also deduce that the optimal shifting-phase encoding range is [-77°, 77°] for ISPM, and is [-61°, 61°] for ICM, and is [34°, 74°] for MCA. For wrapped phase errors, the distributions of ICM and MCA exhibit a U-shaped distribution, while ISPM demonstrates a uniform distribution. Based on theoretical analysis and experiment results, this paper gives recommendations for better use of these methods to boost their accuracy and offers valuable guidance for selecting an appropriate variant shifting-phase coding method under the specific measurement requirements.

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Section: Error Models Of Icmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparative study of variant shifting-phase coding method based on noise error model

Wu,

Mu,

Cheng

et al. 2024

Meas. Sci. Technol.

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“…Currently, the demodulation method of PSI can be divided into two main types: multi-step phase shift algorithm and two-step phase shift algorithm. Among them, 4-step, 5-step and N-step phase shift algorithms are proposed firstly [3][4][5][6][7] . Then, Wang, etc.…”

Section: Introductionmentioning

confidence: 99%

An anti-vibration phase demodulation method applied to phase-shifting interferometric

Chen

Zhong

Tang

et al. 2022

Seventeenth National Conference on Laser Technology and Optoelectronics

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As a high-precision detection technique of surface topography based on the interference theory of light, Phase-Shifting Interferometric is susceptible to vibration from the surrounding environment, which reduces the detection accuracy. In order to reduce the influence of vibration errors and improve the phase demodulation accuracy of measured wavefront, an anti-vibration phase demodulation method applied to Phase-Shifting Interferometric is proposed in this paper. This method first acquires two sequences of interference images with phase shifts of 0 and 𝜋𝜋/2 respectively, uses a digital image stabilization algorithm to suppress the vibration error of each frame in the sequence, and synthesizes two frames of interference images with phase shifts of 0 and 𝜋𝜋/2, respectively. Then, based on these two frames of synthesized images with determined phase shifts, the gradient algorithm and the Schmidt Orthogonal Transform are used for wavefront phase demodulation. The experimental results show that the percentage of pixels demodulated effectively at the truncated interface is more than 90%. Compared with the traditional demodulation method, the number of pixels demodulated effectively (demodulation accuracy) is improved.

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“…Information on object height is obtained by demodulating the fringes that are previously modulated by the height on the surface of the object in this method. Common fringe projection measurement techniques include phase measuring profilometry (PMP) [9,10], Fourier transform profilometry (FTP) [11], and Moire profilometry (MP). Compared to Fourier transform profilometry and convolutional demodulation, phase measurement profilometry requires more fringe patterns and slightly longer acquisition time.…”

Section: Introductionmentioning

confidence: 99%

A New Face Recognition Method for Intelligent Security

Wang

Zhang

et al. 2020

Applied Sciences

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With the advent of the era of artificial intelligence and big data, intelligent security robots not only improve the efficiency of the traditional intelligent security industry but also propose higher requirements for intelligent security. Aiming to solve the problem of long recognition time and high equipment cost of intelligent security robots, we propose a new face recognition method for intelligent security in this paper. We use the Goldstein branching method for phase unwrapping, which can improve the three-dimensional (3D) face reconstruction effect. Subsequently, by using the three-dimensional face recognition method based on face radial curve elastic matching, different weights are assigned to different curve recognition similarity for weighted fusion as the total similarity for recognition. Experiments show that the method has a higher face recognition rate and is robust to attitude, illumination, and noise.

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Modified five-step phase-shift algorithm for 3D profile measurement

Cited by 13 publications

References 27 publications

Comparative study of variant shifting-phase coding method based on noise error model

Comparative study of variant shifting-phase coding method based on noise error model

An anti-vibration phase demodulation method applied to phase-shifting interferometric

A New Face Recognition Method for Intelligent Security

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