Nonlinear effect of the structured light profilometry in the phase-shifting method and error correction

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This paper conducts a trade-off between efficiency and accuracy of three-dimensional (3D) shape measurement based on the triangulation principle, and introduces a flying and precise 3D shape measurement method based on multiple parallel line lasers. Firstly, we establish the measurement model of the multiple parallel line lasers system, and introduce the concept that multiple base planes can help to deduce the unified formula of the measurement system and are used in simplifying the process of the calibration. Then, the constraint of the line spatial frequency, which maximizes the measurement efficiency while ensuring accuracy, is determined according to the height distribution of the object. Secondly, the simulation analyzing the variation of the systemic resolution quantitatively under the circumstance of a set of specific parameters is performed, which provides a fundamental thesis for option of the four system parameters. Thirdly, for the application of the precision measurement in the industrial field, additional profiles are acquired to improve the lateral resolution by applying a motor to scan the 3D surface. Finally, compared with the line laser, the experimental study shows that the present method of obtaining 41220 points per frame improves the measurement efficiency. Furthermore, the accuracy and the process of the calibration are advanced in comparison with the existing multiple-line laser and the structured light makes an accuracy better than 0.22 mm at a distance of 956.02 mm.

Section: Introductionmentioning

confidence: 99%

A fast and precise three-dimensional measurement system based on multiple parallel line lasers

Wang¹,

Lin²

2021

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“…Actually, it remains difficult to obtain high accuracy and high speed simultaneously. [1][2][3] The conventional DFP technique uses 8-bit sinusoidal fringes. which limits the measurement speed to the projector refresh rate (typically 120 Hz).…”

Section: Introductionmentioning

confidence: 99%

“…[5] The binary defocusing techniques have been developed to break the speed bottleneck. [1,6,7] Moreover, nonlinear gamma can be eliminated automatically with 1-bit depth patterns. However, some additional issues are present and need handling: (i) the smaller depth range and (ii) the high-order harmonic error.…”

Section: Introductionmentioning

confidence: 99%

Multi-objective strategy to optimize dithering technique for high-quality three-dimensional shape measurement*

Cai¹,

Chen²,

Cao

et al. 2019

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Dithering optimization techniques can be divided into the phase-optimized technique and the intensity-optimized technique. The problem with the former is the poor sensitivity to various defocusing amounts, and the problem with the latter is that it cannot enhance phase quality directly nor efficiently. In this paper, we present a multi-objective optimization framework for three-dimensional (3D) measurement by utilizing binary defocusing technique. Moreover, a binary patch optimization technique is used to solve the time-consuming issue of genetic algorithm. It is demonstrated that the presented technique consistently obtains significant phase performance improvement under various defocusing amounts.

“…Three-dimensional (3D) depth data acquisition techniques are becoming increasingly important for video game design, animation, movies, virtual reality, telesurgery, medicine, homeland security and manufacturing. [1] Among these techniques, the digital fringe projection (DFP) techniques have the great potential to be an integrated part of intelligent systems due to their simplicity, reliability and flexibility. [2] To reconstruct the 3D depth data, the DFP technique utilizes a projector to project a sequence of sinusoidal phase-shifted fringe patterns onto the surface of an object, and a camera to capture the deformed fringe patterns.…”

Section: Introductionmentioning

confidence: 99%

Optimized dithering technique in frequency domain for high-quality three-dimensional depth data acquisition*

Cai¹,

Chen²,

Cao³

et al. 2019

On the basis of the objective functions, dithering optimization techniques can be divided into the intensity-based optimization technique and the phase-based optimization technique. However, both types of techniques are spatial-domain optimization techniques, while their measurement performances are essentially determined by the harmonic components in the frequency domain. In this paper, a novel genetic optimization technique in the frequency domain is proposed for high-quality fringe generation. In addition, to handle the time-consuming difficulty of genetic algorithm (GA), we first optimize a binary patch, then join the optimal binary patches together according to periodicity and symmetry so as to generate a full-size pattern. It is verified that the proposed technique can significantly enhance the measured performance and ensure the robustness to various amounts of defocusing.