Multi-step variable frequency projected fringe measurement method for measuring each point on object independently
A technique of projecting fringes and variable frequency, which is applied in the direction of measuring devices, instruments, and optical devices, etc. It can solve the problems of unwrapping results and difficult application of isolated and discontinuous objects.
Inactive Publication Date: 2015-01-07
XI AN JIAOTONG UNIV +1
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Problems solved by technology
Therefore, good unwrapping results cannot be obtained when the parcel map contains shadows, broken stripes, and discontinuous objects (with mutations).
However, most of the current projected fringe surface measurement methods require a phase unwrapping process, which makes it difficult for these methods to be applied to the measurement of objects with isolated and discontinuous regions, which are the most common in engineering
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[0030] The hardware system used in the present invention is the same as the common projection fringe measurement system, and the projection fringe measurement system includes: a fringe generation optical device, a CCD camera, and a computer.
[0031] The accompanying drawings and the following descriptions use a projector as an optical device for fringe generation, and take 16 continuously changing fringes of different spatial frequencies as examples to illustrate the implementation method of the present invention.
[0032] figure 1 It is a specific flow chart of measuring the surface shape of an object in the present invention. When the computer is used to change the spatial frequency of the projected stripes to D 1 ~D 16 , for each spatial frequency D i , use the computer to control its phase change, and the CCD camera collects the initial phase as 0, π, The image of the object and the floor image without placing the object; use the four-step phase shift method to obt...
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The invention discloses a multi-step variable frequency projected fringe measurement method for measuring each point on an object independently, belonging to the technical field of photoelectric measurement. The method dispenses with phase unwrapping. The method is characterized in that wrapped phase diagrams of fringes with different space frequencies can be obtained by projecting multiple variable frequency fringe diagrams on the surface of the object, and phase summation and peak search processing are carried out on the obtained multiple wrapped phase diagrams, thus obtaining absolute height distribution of the object without phase unwrapping and avoiding the impacts of errors generated in the phase unwrapping process on the measurement results. The method has the following beneficial effects: as the step of unwrapping is omitted and the height information of each point is obtained independently, the method can be used for measuring the objects with discontinuous and choppy surfaces and theoretically can be used for measuring objects in any complex shapes.
Description
technical field [0001] The invention relates to a method for measuring the surface shape of complex discontinuous objects without phase unwrapping and multi-step frequency-variable projection fringe measurement method, which belongs to the field of photoelectric measurement technology. Background technique [0002] The projection fringe optical three-dimensional shape measurement method has the advantages of non-contact, fast measurement speed, high efficiency and non-destructiveness. It can be used to measure surface parameters such as machined surfaces, automobile shapes, and human bodies, and has broad application prospects in precision machinery, aerospace and other fields. [0003] According to the literature search, the existing projection fringe optical three-dimensional shape measurement methods can be classified into Moiré profilometry, phase measurement profilometry (PMP), Fourier transform profilometry (FTP) according to different processing methods for projection...
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IPC IPC(8): G01B11/25
Inventor 贾书海许勇陈花铃
Owner XI AN JIAOTONG UNIV