A new phase unwrapping method for phase shifting profilometry with object in motion

Phase unwrapping is an important step for the phase shifting profilometry. The dual-frequency phase unwrapping method can unwrap the object with discontinues when the object is static by employing more fringe patterns. However, errors will occur when moving object is reconstructed. In this paper, a new phase unwrapping method with dual-frequency phase unwrapping method for the moving object measurement is proposed. The fringe pattern with low fringe pattern and high frequency are projected onto the moving object surface. Then, the phase values are retrieved for the two frequencies respectively. The relationship between the movement and phase value is analyzed and the phase variations caused by the movement is compensated. At last, the phase value is unwrapped by the traditional dual-frequency phase unwrapping method. The effectiveness of the proposed method is verified by simulations

Automated approach for the surface profile measurement of moving objects based on PSP

Phase shifting profilometry can achieve high accuracy for the 3D shape measurement of static object. Errors will be introduced when the object is moved during the movement. The fundamental reason causing the above issue is: PSP requires multiple fringe patterns but the reconstruction model does not include the object movement information. This paper proposes a new method to automatically measure the 3D shape of the rigid object with arbitrary 2D movement. Firstly, the object movement is tracked by the SIFT algorithm and the rotation matrix and translation vector describing the movement are estimated. Then, with the reconstruction model including movement information, a least-square algorithm is applied to retrieve the correct phase value. The proposed method can significantly reduce the errors caused by the object movement. The whole reconstruction process does not need human intervention and the proposed method has high potential to be applied in industrial applications. Experiments are presented to verify the effectiveness

Reconstruction of isolated moving objects with high 3D frame rate based on phase shifting profilometry

Recently, moving object reconstruction based on PSP has been attracted intensive research. The errors caused by the inner movement of PSP have been addressed successfully. However, when the object with discontinuities or isolated surface is measured and the temporal phase unwrapping method is applied, additional fringe patterns are required to unwrap the phase map. The object movement between the PSP fringe patterns and additional fringe patterns will cause unwrapping errors. This paper proposes a new method to reconstruct the moving object with discontinuous or isolated surface. The object movement is tracked and the influence on the phase map caused by the movement is analyzed. Then, the phase variation caused by the movement is obtained. The phase map of the object before movement is obtained by compensating the phase map of the object after movement based on the phase variations. Finally, the object is reconstructed by dual-frequency phase unwrapping method. A new projection strategy increasing the efficiency of the 3D frame rate is also presented in this paper. The 3D frame rate achieves half of the camera capture speed. The proposed method has high potential to be applied in industrial applications for real-time measurement of moving objects. Experiments are presented to verify the effectiveness

Design and evaluation of a light-field multi-wavelength pyrometer

This letter describes the design and implementation of a multi-wavelength light-field pyrometer, where six-channel radiation images were captured with one CMOS sensor. Such capability is achieved by placing a 2 × 3 filter array in front of the main lens of an unfocused light-field camera, such that discrete wavelength and radiation intensity can be simultaneously recorded. It demonstrates that through black-body furnace experiments, how multi-channel radiation images can be extracted from one raw light-field multispectral image, and how accurate 2D temperature distribution can be recovered by optimization algorithms.Published versionThis work was supported by the National Natural Science Foundation of China (Grant Nos. 12172222 and 12002209) and the Aero Engine Corporation of China (Grant No. HFZL2020CXY014-2)

General model for phase shifting profilometry with an object in motion

When implementing the phase shifting profilometry to reconstruct an object, the object is always required to be kept stable as multiple fringe patterns are required. Movement during the measurement will cause failed reconstruction. This paper proposes a general model describing the fringe patterns with any three-dimensional movement based on phase shifting profilometry. The object movement is classified as five types and their characteristics are analyzed respectively. Then, by introducing a virtual plane, the influence on the phase value caused by different types of movement is described mathematically and a new model including movement information is proposed. At last, with the help of the movement tracking and least-square algorithm, the moving object is reconstructed with high accuracy. The proposed method can remove the reference plane during the reconstruction of the moving object, which extends the application range of the phase shifting profilometry. The effectiveness of the proposed model is verified by the experiments. 2018 Optical Society of Americ

Supplementary document for Light Field Camera Calibration and PSF Calculation Based on Differentiable Ray Tracing - 6830703.pdf

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A new phase retrieve method for phase shifting profilometry with object in motion

Phase retrieve is an important step for phase shifting profilometry (PSP). The existing phase retrieve methods can obtain the phase value successfully for static object. However, as multiple fringe patterns are required in PSP, when the object has movement, errors will be introduced. A new phase retrieve method for the object with 2D movement is proposed in this paper. The 2D movement is divided into translation movement and rotation movement. Then their influence on the phase value is analyzed and a new reconstruction model including the movement information is given. At last, the phase value is retrieved based on the new reconstruction model. The proposed method can eliminate the errors caused by 2D movement of object. The effectiveness of the proposed method is verified by simulations