Light emitted by an object placed in a transparent protective cover will change its original propagation direction before entering a fringe projection profilometry (FPP) system due to the influence of light refraction. This Letter proposes refractive FPP for accurate three-dimensional (3D) shape measurement. The method derives a coordinate mapping between a 3D measurement space and a 2D space formed by an incident ray, a normal of a refractive interface, and an emergent ray. Based on the coordinate mapping, the equation of the emergent ray in the 3D space can be directly determined with the equation of the incident ray and used for 3D measurement without refraction error. For validation, an FPP system through a planar glass was established and used for 3D shape measurements of a ring board, a regular sphere, and two objects with complex surfaces. Experimental results demonstrate the effectiveness and accuracy of the proposed refractive FPP.
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http://dx.doi.org/10.1364/OL.500208 | DOI Listing |
Sensors (Basel)
December 2024
Department of Electrical Engineering, Chinese Culture University, Taipei 11114, Taiwan.
This paper presents an effective three-dimensional (3D) surface reconstruction technique aimed at profiling composite surfaces with both specular and diffuse reflectance. Three-dimensional measurements based on fringe projection techniques perform well on diffuse reflective surfaces; however, when the measurement targets contain both specular and diffuse components, the efficiency of fringe projection decreases. To address this issue, the proposed technique integrates digital holography into the fringe projection setup, enabling the simultaneous capture of both specular and diffuse reflected light in the same optical path for full-field surface profilometry.
View Article and Find Full Text PDF3D Print Addit Manuf
October 2024
School of Electrical Engineering, Yancheng Institute of Technology, Yancheng, Jiangsu, China.
3D printing is an indispensable technology in modern life and is widely used in aerospace, exoskeleton, and architecture. The increasing accuracy requirements of 3D printed objects in these fields require high-precision measurement methods to obtain accurate data. Based on the precision measurement requirements, in this study, a fast multifrequency phase unwrapping method based on 3D printing object appearance acquisition is proposed.
View Article and Find Full Text PDFPhase unwrapping is crucial in fringe projection profilometry (FPP) 3D measurement. However, achieving efficient and robust phase unwrapping remains a challenge, particularly when dealing with high-frequency fringes to achieve high accuracy. Existing methods rely on heavy fringe projections, inevitably sacrificing measurement efficiency.
View Article and Find Full Text PDFSensors (Basel)
November 2024
Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.
In the field of fringe projection profilometry, phase sensitivity is a critical factor influencing the precision of object measurements. Traditional techniques that employ basic horizontal or vertical fringe projection often do not achieve optimal levels of phase sensitivity. The identification of the fringe angle that exhibits optimal phase sensitivity has been a significant area of research.
View Article and Find Full Text PDFJ Pers Med
November 2024
Department of Maxillofacial Surgery, University of Münster, Albert-Schweitzer-Campus 1, Building W30, 48149 Münster, Germany.
It is generally accepted that the symmetry of the face plays a significant role in the visual perception of its attractiveness. Therefore, its objective assessment could be useful for individual therapy planning. However, there is an ongoing debate about whether completely symmetrical faces are less attractive than those with minor deviations.
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