Research

15 pages, 4082 KiB

Open AccessArticle

Motion-Induced Phase Error Compensation Using Three-Stream Neural Networks

by Yueyang Li, Wenbo Guo, Junfei Shen, Zhoujie Wu and Qican Zhang

Appl. Sci. 2022, 12(16), 8114; https://0-doi-org.brum.beds.ac.uk/10.3390/app12168114 - 13 Aug 2022

Cited by 9 | Viewed by 1260

Phase-shifting profilometry (PSP) has been widely used in the measurement of dynamic scenes. However, the object motion will cause a periodical motion-induced error in the phase map, and there is still a challenge to eliminate it. In this paper, we propose a method [...] Read more.

Phase-shifting profilometry (PSP) has been widely used in the measurement of dynamic scenes. However, the object motion will cause a periodical motion-induced error in the phase map, and there is still a challenge to eliminate it. In this paper, we propose a method based on three-stream neural networks to reduce the motion-induced error, while a general dataset establishment method for dynamic scenes is presented to complete three-dimensional (3D) shape measurement in a virtual fringe projection system. The numerous automatically generated data with various motion types is employed to optimize models. Three-step phase-shift fringe patterns captured along a time axis are divided into three groups and processed by trained three-stream neural networks to produce an accurate phase map. The actual experiment’s results demonstrate that the proposed method can significantly perform motion-induced error compensation and achieve about 90% improvement compared with the traditional three-step phase-shifting algorithm. Benefiting from the robust learning-based technique and convenient digital simulation, our method does not require empirical parameters or complex data collection, which are promising for high-speed 3D measurement. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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10 pages, 4281 KiB

Open AccessArticle

Reconstruction of Isolated Moving Objects by Motion-Induced Phase Shift Based on PSP

by Ke Wu, Min Li, Lei Lu and Jiangtao Xi

Appl. Sci. 2022, 12(1), 252; https://0-doi-org.brum.beds.ac.uk/10.3390/app12010252 - 28 Dec 2021

Cited by 4 | Viewed by 1470

Abstract

The reconstruction of moving objects based on phase shifting profilometry has attracted intensive interests. Most of the methods introduce the phase shift by projecting multiple fringe patterns, which is undesirable in moving object reconstruction as the errors caused by the motion will be [...] Read more.

The reconstruction of moving objects based on phase shifting profilometry has attracted intensive interests. Most of the methods introduce the phase shift by projecting multiple fringe patterns, which is undesirable in moving object reconstruction as the errors caused by the motion will be intensified when the number of the fringe pattern is increased. This paper proposes the reconstruction of the isolated moving object by projecting two fringe patterns with different frequencies. The phase shift required by the phase shifting profilometry is generated by the object motion, and the model describing the motion-induced phase shift is presented. Then, the phase information in different frequencies is retrieved by analyzing the influence introduced by movement. Finally, the mismatch on the phase information between the two frequencies is compensated and the isolated moving object is reconstructed. Experiments are presented to verify the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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13 pages, 4115 KiB

Open AccessArticle

A Binocular Vision-Based 3D Sampling Moiré Method for Complex Shape Measurement

by Wenxiong Shi, Qi Zhang, Huimin Xie and Wei He

Appl. Sci. 2021, 11(11), 5175; https://0-doi-org.brum.beds.ac.uk/10.3390/app11115175 - 02 Jun 2021

Cited by 10 | Viewed by 2484

Abstract

As a promising method for moiré processing, sampling moiré has attracted significant interest for binocular vision-based 3D measurement, which is widely used in many fields of science and engineering. However, one key problem of its 3D shape measurement is that the visual angle [...] Read more.

As a promising method for moiré processing, sampling moiré has attracted significant interest for binocular vision-based 3D measurement, which is widely used in many fields of science and engineering. However, one key problem of its 3D shape measurement is that the visual angle difference between the left and right cameras causes inconsistency of the fringe image carrier fields, resulting in the phase mismatch of sampling moiré. In this paper, we developed a phase correction method to solve this problem. After epipolar rectification and carrier phase introduction and correction, the absolute phase of the fringe images was obtained. A more universal 3D sampling moiré measurement can be achieved based on the phase match and binocular vision model. Our numerical simulation and experiment showed the high robustness and anti-noise ability of this new 3D sampling moiré method for high-precision 3D shape measurement. As an application, cantilever beams are fabricated by directed energy deposition (DED) using different process parameters, and their 3D deformation caused by residual stresses is measured, showing great potential for residual stress analyses during additive manufacturing. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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12 pages, 5641 KiB

Open AccessArticle

Online Phase Measurement Profilometry for a Fast-Moving Object

by Jie Gao, Yiping Cao, Jin Chen and Xiuzhang Huang

Appl. Sci. 2021, 11(6), 2805; https://0-doi-org.brum.beds.ac.uk/10.3390/app11062805 - 21 Mar 2021

Cited by 4 | Viewed by 1468

Abstract

When the measured object is fast moving online, the captured deformed pattern may appear as motion blur, and some phase information will be lost. Therefore, the frame rate has to be improved by adjusting the image acquisition mode of the camera to adapt [...] Read more.

When the measured object is fast moving online, the captured deformed pattern may appear as motion blur, and some phase information will be lost. Therefore, the frame rate has to be improved by adjusting the image acquisition mode of the camera to adapt to a fast-moving object, but the resolution of the captured deformed pattern will be sacrificed. So a super-resolution image reconstruction method based on maximum a posteriori (MAP) estimation is adopted to obtain high-resolution deformed patterns, and in this way, the reconstructed high-resolution deformed patterns also have a good effect on noise suppression. Finally, all the reconstructed high-resolution equivalent phase shifting deformed patterns are used for online three-dimensional (3D) reconstruction. Experimental results prove the effectiveness of the proposed method. The proposed method has a good application prospect in high-precision and fast online 3D measurement. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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18 pages, 5982 KiB

Open AccessArticle

Indentation Measurement in Thin Plates under Bending Using 3D Digital Image Correlation

by Juan-Antonio Almazán-Lázaro, Elías López-Alba, Luis Rubio-García and Francisco-Alberto Díaz-Garrido

Appl. Sci. 2021, 11(6), 2706; https://0-doi-org.brum.beds.ac.uk/10.3390/app11062706 - 17 Mar 2021

Cited by 3 | Viewed by 2168

Abstract

In the current paper, a novel experimental methodology to characterize the contact behavior on thin plates under bending is presented. The method is based on the experimental measurement of the indentation observed during contact experiments. Tests were conducted using aluminum thin plates and [...] Read more.

In the current paper, a novel experimental methodology to characterize the contact behavior on thin plates under bending is presented. The method is based on the experimental measurement of the indentation observed during contact experiments. Tests were conducted using aluminum thin plates and a steel sphere to evaluate the effect of thickness and bending during contact. For this purpose, a non-contact optical technique, 3D Digital Image Correlation (3D-DIC), has been employed to measure the out-of-plane displacements experienced at the rear face of the specimens (opposite where the contact is occurring). An indirect measurement of the experimental contact law is obtained for different plate thicknesses (2 mm, 3 mm, 4 mm, 5 mm and 6 mm) as the contact load increases. An energy balance performed during contact experiments made it possible to evaluate and quantify the applied energy to generate bending and contact deformation. When the specimen thickness increases from 2 mm to 6 mm, contact deformation reaches higher values from the total applied energy. In addition, it is also possible to evaluate the portion of the elastically recovered energy for contact and bending deformation during the unloading. It has been observed that thicker specimens show a lower elastic energy recovery due to bending and a higher elastic energy recovery due to contact. Results clearly show how the ratio between absorbed and applied energy changes as the specimen thickness increases, highlighting the relevance of the proposed method for the characterization of contact behavior in thin plates. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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11 pages, 4146 KiB

Open AccessArticle

Single-Shot Phase Measuring Profilometry Based on Quaternary Grating Projection

by Chaozhi Yang, Yiping Cao and Xiuzhang Huang

Appl. Sci. 2021, 11(6), 2536; https://0-doi-org.brum.beds.ac.uk/10.3390/app11062536 - 12 Mar 2021

Cited by 3 | Viewed by 1456

Abstract

In this paper, we propose a new single-shot three-dimensional (3D) measuring method based on quaternary grating projection. In traditional binary grating phase measuring profilometry (PMP), a multi-step or color fringe pattern are usually used to extract the sinusoidal fringes. In our proposed method, [...] Read more.

In this paper, we propose a new single-shot three-dimensional (3D) measuring method based on quaternary grating projection. In traditional binary grating phase measuring profilometry (PMP), a multi-step or color fringe pattern are usually used to extract the sinusoidal fringes. In our proposed method, by using the DLP4500’s 2-bit gray coding mode, the grayscale is quaternary. The three non-zero grayscales cyclically arranged in equal width, and the fourth grey value is 0 which is not encoded in the fringe pattern but represents the shadow information in the deformed pattern, where a quaternary grating is encoded. When the DLP4500 projects the quaternary grating onto the measured object, the charge coupled device (CCD) captures the corresponding deformed pattern synchronously. Three frames of binary deformed patterns with 1/3 duty cycle and a relative displacement of 1/3 period can be decomposed by the segmentation algorithm proposed in this paper. Three sinusoidal deformed patterns with a 2π/3 shift-phase can be obtained by extracting the fundamental frequency of the three binary deformed patterns correspondingly, and the 3D shape of the object can be reconstructed by PMP. Experimental results show the effectiveness and feasibility of the proposed method. Because the DLP4500 only needs 2-bit coded grating for projection, the refresh rate of the projected grating is as high as 1428 Hz, which will have a broad application prospect in real time and fast online measurement. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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11 pages, 3741 KiB

Open AccessArticle

A Single-Shot 3D Measuring Method Based on Quadrature Phase-Shifting Color Composite Grating Projection

by Xiuzhang Huang, Yiping Cao, Chaozhi Yang, Yujiao Zhang and Jie Gao

Appl. Sci. 2021, 11(6), 2522; https://0-doi-org.brum.beds.ac.uk/10.3390/app11062522 - 11 Mar 2021

Cited by 3 | Viewed by 1569

Abstract

A single-shot three-dimensional measuring method based on quadrature phase-shifting color composite grating projection is proposed. Firstly, three quadrature phase-shifting sinusoidal gratings are encoded in red (R), green (G), and blue (B) channels respectively, composed single- frame color composite grating. This color composite grating [...] Read more.

A single-shot three-dimensional measuring method based on quadrature phase-shifting color composite grating projection is proposed. Firstly, three quadrature phase-shifting sinusoidal gratings are encoded in red (R), green (G), and blue (B) channels respectively, composed single- frame color composite grating. This color composite grating is projecting obliquely on the object by DLP. After that, the color camera which is placed in a specific location is used to capture the corresponding color deformed pattern and send it to the PC. Then, by color separation, the color deformed pattern is demodulated as the corresponding three-frame monochromatic deformed patterns with a shifted quadrature phase. Due to the existences of sensitivity differences and color crosstalk among the tricolor channels, we propose a gray imbalance correction method based on the DC component’s consistency approximation. By the established 3D reconstruction physical model, the measurement of 3D shape can be achieved. Many experimental results for static and moving objects prove the proposed method’s feasibility and practicability. Owing to the single-shot feature of the proposed method, it has a good application prospect in real-time and high-speed 3D measurement. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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17 pages, 7353 KiB

Open AccessArticle

Design and Analysis of High-Accuracy Telecentric Surface Reconstruction System Based on Line Laser

by Linshen Yao and Haibo Liu

Appl. Sci. 2021, 11(2), 488; https://0-doi-org.brum.beds.ac.uk/10.3390/app11020488 - 06 Jan 2021

Cited by 7 | Viewed by 2689

Abstract

Non-contact measurement technology based on triangulation with cameras is extensively applied to the development of computer vision. However, the accuracy of the technology is generally not satisfactory enough. The application of telecentric lenses can significantly improve the accuracy, but the view of telecentric [...] Read more.

Non-contact measurement technology based on triangulation with cameras is extensively applied to the development of computer vision. However, the accuracy of the technology is generally not satisfactory enough. The application of telecentric lenses can significantly improve the accuracy, but the view of telecentric lenses is limited due to their structure. To address these challenges, a telecentric surface reconstruction system is designed for surface detection, which consists of a single camera with a telecentric lens, line laser generator and one-dimensional displacement platform. The designed system can reconstruct the surface with high accuracy. The measured region is expanded with the used of the displacement platform. To achieve high-accuracy surface reconstruction, we propose a method based on a checkerboard to calibrate the designed system, including line laser plane and motor direction of the displacement platform. Based on the calibrated system, the object under the line laser is measured, and the results of lines are assembled to make the final surface reconstruction. The results show that the designed system can reconstruct a region of

20 \times 40 {mm}^{2}

, up to the accuracy of micron order. Full article

(This article belongs to the Special Issue Time-Series Measurements of 3D Shape and Deformation Using Image Analysis)

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