scholarly journals Single-Shot Phase Measuring Profilometry Based on Quaternary Grating Projection

2021 ◽  
Vol 11 (6) ◽  
pp. 2536
Author(s):  
Chaozhi Yang ◽  
Yiping Cao ◽  
Xiuzhang Huang
Keyword(s):  
Fringe Pattern ◽  
Three Dimensional ◽  
Measuring Method ◽  
Relative Displacement ◽  
Single Shot ◽  
Refresh Rate ◽  
Charge Coupled Device ◽  
Phase Measuring Profilometry ◽  
Color Fringe ◽  
Binary Grating

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.

A stroboscopic online three-dimensional measurement for fast rotating object with binary dithered patterns

2017 ◽  
Vol 40 (8) ◽  
pp. 2660-2668 ◽  
Author(s):  
Yuting Chen ◽  
Yiping Cao ◽  
Han Yuan ◽  
Yingying Wan
Keyword(s):  
Three Dimensional ◽  
Control Unit ◽  
Ccd Camera ◽  
Fixed Position ◽  
Charge Coupled Device ◽  
Object A ◽  
Phase Measuring Profilometry ◽  
Three Dimensional Measurement ◽  
Binary Grating ◽  
Fast Rotating

In the three-dimensional (3D) measurement, phase measuring profilometry (PMP) requires no less than three deformed sinusoidal patterns, limiting its applications to static scenarios only. In this paper, a stroboscopic online PMP for fast rotating object with binary dithered patterns is proposed. N frames of novel circular binary grating patterns are designed to measure a rotating object. A defocused digital light projector projects the designed patterns onto the object with stroboscopic method, the corresponding deformed patterns can be “frozen” by charge-coupled device (CCD) camera. Owing to the repeatability and periodicity of rotating movement, a synchronization control unit is used to keep the object at the fixed position in each “frozen” deformed pattern. Every projected pattern is shifted from the previous pattern by a factor of 2π/N. This method makes the images of the object appear stationary in the deformed patterns. The experimental results show the accurate 3D shape of fast rotating object can be reconstructed with the proposed method.

scholarly journals Single-shot detection of 8 unique monochrome fringe patterns representing 4 distinct directions via multispectral fringe projection profilometry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Parsa Omidi ◽  
Mohamadreza Najiminaini ◽  
Mamadou Diop ◽  
Jeffrey J. L. Carson
Keyword(s):  
Spatial Resolution ◽  
Fringe Pattern ◽  
Three Dimensional ◽  
Fringe Projection ◽  
Video Frame ◽  
Single Shot ◽  
Shot Detection ◽  
Fringe Patterns ◽  
Fringe Projection Profilometry ◽  
Multispectral Camera

AbstractSpatial resolution in three-dimensional fringe projection profilometry is determined in large part by the number and spacing of fringes projected onto an object. Due to the intensity-based nature of fringe projection profilometry, fringe patterns must be generated in succession, which is time-consuming. As a result, the surface features of highly dynamic objects are difficult to measure. Here, we introduce multispectral fringe projection profilometry, a novel method that utilizes multispectral illumination to project a multispectral fringe pattern onto an object combined with a multispectral camera to detect the deformation of the fringe patterns due to the object. The multispectral camera enables the detection of 8 unique monochrome fringe patterns representing 4 distinct directions in a single snapshot. Furthermore, for each direction, the camera detects two π-phase shifted fringe patterns. Each pair of fringe patterns can be differenced to generate a differential fringe pattern that corrects for illumination offsets and mitigates the effects of glare from highly reflective surfaces. The new multispectral method solves many practical problems related to conventional fringe projection profilometry and doubles the effective spatial resolution. The method is suitable for high-quality fast 3D profilometry at video frame rates.

Single-shot phase measuring profilometry based on color binary grating with intervals

2019 ◽  
Vol 451 ◽  
pp. 268-275 ◽  
Author(s):  
Yapin Wang ◽  
Yiping Cao ◽  
Guangkai Fu ◽  
Lu Wang ◽  
Yingying Wan ◽  
...  
Keyword(s):  
Single Shot ◽  
Phase Measuring Profilometry ◽  
Binary Grating

Three-Dimensional Shape Measurement Based on Single-Shot Color Fringe Projection of Sinusoidal Grating

2011 ◽  
Vol 31 (7) ◽  
pp. 0712002
Author(s):  
戴美玲 Dai Meiling ◽  
杨福俊 Yang Fujun ◽  
杜晓磊 Du Xiaolei ◽  
何小元 He Xiaoyuan
Keyword(s):  
Three Dimensional ◽  
Fringe Projection ◽  
Shape Measurement ◽  
Sinusoidal Grating ◽  
Single Shot ◽  
Dimensional Shape ◽  
Color Fringe ◽  
Three Dimensional Shape

Three-dimensional shape measurement for thin objects based on hue-height mapping using color-encoded fringe projection

2017 ◽  
Vol 40 (14) ◽  
pp. 3978-3984 ◽  
Author(s):  
Yingying Wan ◽  
Yiping Cao ◽  
Cheng Chen ◽  
Guangkai Fu ◽  
Yapin Wang
Keyword(s):  
Fringe Pattern ◽  
Three Dimensional ◽  
Fringe Projection ◽  
Shape Measurement ◽  
3D Shape ◽  
3D Shape Measurement ◽  
Color Calibration ◽  
Dimensional Shape ◽  
Color Fringe ◽  
Fringe Patterns

Three-dimensional (3D) shape measurement based on hue-height mapping using color-encoded fringe projection is proposed for thin objects. The projected color-encoded fringe pattern is encoded by three sinusoidal fringe patterns with 2π/3 shift phase in between into red (R), green (G) and blue (B) channels, separately. It is found that the hue component is of periodicity with the same period as the sinusoidal fringe pattern in the R channel of the color-encoded fringe and the hue distribution in a period is of monotonicity. While this color-encoded fringe pattern is projected onto an object, as long as the deformation of the captured deformed color fringe pattern is not out of a period, the 3D shape of the measured object can be reconstructed directly by hue-height mapping. This method is concise and fast with no color calibration to remove color crosstalk and no time-consuming phase extraction or phase unwrapping. The experimental results show the feasibility and the practicability of the proposed method.

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

2021 ◽  
Vol 11 (6) ◽  
pp. 2522
Author(s):  
Xiuzhang Huang ◽  
Yiping Cao ◽  
Chaozhi Yang ◽  
Yujiao Zhang ◽  
Jie Gao
Keyword(s):  
High Speed ◽  
Moving Objects ◽  
Three Dimensional ◽  
Measuring Method ◽  
Correction Method ◽  
Phase Shifting ◽  
Single Shot ◽  
Color Separation ◽  
Quadrature Phase ◽  
Color Composite

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.

Development of a Visual Monitoring System for Deformation Measuring of Welded Members and its Application

2008 ◽  
Vol 580-582 ◽  
pp. 557-560 ◽  
Author(s):  
J.G. Han ◽  
Kyong Ho Chang ◽  
Gab Chul Jang ◽  
K.K. Hong ◽  
Sam Deok Cho ◽  
...  
Keyword(s):  
Monitoring System ◽  
Three Dimensional ◽  
Measuring Method ◽  
Welding Residual Stress ◽  
Measuring System ◽  
Visual Monitoring ◽  
Test Error ◽  
Steel Members ◽  
Loading Tests ◽  
Visual Monitoring System

Recently, in the loading tests for steel members, the deformation value is measured by calculating a distance of both cross-heads. This measuring method encounters a test error due to various environmental factors, such as initial slip, etc.. Especially, in the case of welded members, the non-uniform deformation behavior in welded joints is observed because of the effect of welding residual stress and weld metal. This is mainly responsible for a test error and a loss of the reliability for used test instruments. Therefore, to improve the accuracy and the applicability of measuring system, it is necessary to employ a visual monitoring system which can accurately measure the local and overall deformation of welded members. In this paper, to accurately measure a deformation of welded members, a visual monitoring system (VMS) was developed by using three-dimensional digital photogrammetry. The VMS was applied to the loading tests of a welded member. The accuracy and the applicability of VMS was verified by comparing to the deformation value measured by a test instrument (MTS-810). The characteristics of the behavior near a welded joint were investigated by using VMS.

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