A Vertical Measurement Method of Three-Dimensional Surface Shape Based on π Phase Shift Method
A technology of three-dimensional surface shape and phase shifting method, which is applied in the direction of measuring devices, instruments, and optical devices, etc., to avoid inaccurate phase shifting, avoiding a large number of captured images, and avoiding the effect that the fundamental frequency cannot be correctly extracted
Active Publication Date: 2021-03-12
CHENGDU UNIV OF INFORMATION TECH
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[0007] Aiming at the defects of large number of profilometry image collections and spectrum aliasing in modulation degree measurement, the present invention provides a method of using π phase shift method to extract modulation degree information to realize vertical measurement of three-dimensional surface shape, so as to effectively solve the problems mentioned in the background technology. technical problem
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[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0048] In view of the many disadvantages of the existing technology, the present invention designs a structured grating. In the modulation-based measurement method, the sinusoidal grating projection is combined with the π phase shift technology to realize the calculation of the modulation distribution, which not only avoids the traditional pha...
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The invention discloses a three-dimensional surface shape vertical measurement method based on a [Pi] phase shift method. The method is characterized in comprising the following steps that: in a scanning process, collecting two fringe patterns on each position, subtracting the two fringe patterns, and carrying out Fourier transform; selecting a proper filtering window to extract fundamental frequency information; calculating modulation degree distribution on the position; and therefore, utilizing a corresponding relationship between the modulation degree and height to reconstruct the three-dimensional surface shape of an object. By use of the method, the problems that an amount of photographed images is large and the phase shift is inaccurate in a traditional phase shift technology can beavoided, meanwhile, the influence of zero frequency on the fundamental frequency information is eliminated, the problems that the fundamental frequency can not be accurately extracted and the like dueto frequency spectrum aliasing in a Fourier transform method can be effectively avoided, and the method has an important meaning and a wide application prospect on the aspects of application in fields including three-dimensional surface shape profilometry, machine vision and the like. Meanwhile, the designed structure optical grating can realize a purpose that the optical grating can accurately carry out a [Pi] phase shift operation in a projection direction, and the problems that phase shift is inaccurate and the like in a traditional phase shift technology are effectively avoided.
Description
technical field [0001] The invention relates to a structured light projection three-dimensional surface shape measurement technology, in particular to a three-dimensional surface shape vertical measurement method based on a π phase shift method in which the projection direction and the fringe pattern detection direction are coaxial. Background technique [0002] The 3D sensing technology based on structured light illumination can save the 3D space information of the object, and thus reconstruct the 3D surface shape of the measured object. This technology has the characteristics of non-contact, high precision, high efficiency, large information capacity and fast speed, and has been widely used in industrial inspection, machine vision, physical profiling, film and television special effects and other fields. Among them, the 3D sensing method based on fringe projection can be divided into two categories according to the structure of the measurement system: the optical 3D surfac...
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IPC IPC(8): G01B11/25
CPCG01B11/2518
Inventor 钟敏陈锋肖朝
Owner CHENGDU UNIV OF INFORMATION TECH