CN105890540A - Digital image correlation-based object out-of-plane deformation phase measurement method - Google Patents
Digital image correlation-based object out-of-plane deformation phase measurement method Download PDFInfo
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Abstract
The present invention discloses a digital image correlation-based object out-of-plane deformation phase measurement method. The method comprises the steps of (1) acquiring an interference fringe image before object deformation as a first frame of interference fringe image, and acquiring an interference fringe image after object deformation as a second frame of interference fringe image; (2) carrying out the gray processing on the first frame of interference fringe image and the second frame of interference fringe image, extracting the fringe frequency of the first frame of interference fringe image, and adopting a sub-pixel related algorithm to calculate an in-plane displacement field between the first frame of interference fringe image and the second frame of interference fringe image; (3) calculating and obtaining the out-of-plane deformation phase information after the object deformation according to the in-plane displacement field and the fringe frequency of the first frame of interference fringe image which are obtained in the step (2), and the relationship among the in-plane displacement field, the fringe frequency of the first frame of interference fringe image and an out-of-plane deformation phase, which is established based on an optical flow basic type. The method is simple and convenient in process, and is suitable for the dynamic measurement.
Description
Technical field
The present invention relates to a kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture.
Background technology
Optical interferometry method, utilizes interference of light to measure, and remolding sensitivity is higher, occupies highly important status in deformation measurement, such as ESPI, holographic interference, moiréinterferometry etc..Interferometric method comprises two parts content: light path is arranged and the information retrieval of deforming stripe.Due to displacement measurement sensitivity with the illumination light in measurement apparatus irradiating angle be correlated with, the most different measurement apparatus, the displacement component of different directions can be measured.Michelson light path is only sensitive to acoplanarity displacement, and symmetrical light path is only sensitive to in-plane displacement.After light path is provided with, from object light and the reference light interference of direct irradiation record medium of object plane, form interference image；Interference image usually presents with the form of interference fringe.By the change of interference fringe before and after comparison body deformability, demodulate the phase information of every bit in bar graph, thus realize deformation measurement.Utilizing image processing techniques to demodulate the deformation phase place in stripe information, conventional method is broadly divided into measurement method time phase and the big class of space phase measurement method two.Time phase measurement method, such as temporal phase-shifting method (Temporal Phase-shifting Method, TPM) etc., to have displacement measurement accuracy high, advantages of simple structure and simple, but such method needs several bar graphs just can complete to measure, and the longest, is typically only applicable to static measurement；Space phase measurement method extracts phase place by spatially obtaining more information, such as spatial phase-shifting method (Spatial Phase-shifting Method, and Fourier converter technique (Fourier Transform Method SPM), FTM) etc., the measurement to dynamic process phase place can be realized.But, the former light path is complex, and precision is relatively low；The processing procedure of the latter is comparatively laborious, is difficulty with the automatization that striped processes.
Meanwhile, above method does not all account for time-parameters for the measurement of displacement field, thus the quantitative measurement to dynamic field just cannot obtain satisfied result.For this problem, there is research worker to propose time series phase method (Time Sequence Phase Method, TSPM), time-parameters is introduced in the middle of speckle interference, successfully extracted phase information, adapt to large deformation, time-varying measurement.But the method cannot be given in displacement directivity and determine value, it is only used in the time-varying field of dullness.In addition, above method is required for carrying out Phase unwrapping operation, this operand adding phase extraction undoubtedly and error.Simultaneously as the details of each striped cannot be judged in striped dense Region, thus the biggest in the phase error of striped intensive place demodulation.
The 1950's, the research worker such as Gribson rebuild principle (Structure From Motion based on motion structure, SFM) concept of light stream (optical flow) is proposed for the first time: in time dependent two-dimensional image sequence, the flowing that the three-dimensional scenic of motion produces due to the change of luminance patterns is light stream.Hereafter, Chinese scholars proposes different optical flow approach successively, and in precision, the many-side such as robustness and real-time all achieves important breakthrough.Method according to optical flow field theory Measuring Object deformation phase place is it is crucial that the optical flow field that extracts between two width bar graphs and the spatial frequency of initial pictures, it is adaptable to the process of high density fringe field.To low-density fringe field and speckle fringes field, according to the method for optical flow field theory Measuring Object deformation phase place when extracting optical flow field (two component u and v of optical flow field), error is the biggest.
Different from optical interferometry method, Digital Image Correlation Method (DIC) be a kind of body surface is deformed before and after the image with dependency carry out correlation computations process and obtain the measuring method of deformation of body field.If the image that the method processes is speckle pattern, it is also called Digital Speckle Correlation Method.This technology has the advantages such as light path is simple, precision is higher, measurement low, the measurement of full field of environmental requirement, all show its practicality and superiority in Experimental Mechanics, existing numerous applications such as field real-time measurement, minute yardstick deformation field measurement.Digital Image Correlation Method (DIC) is the displacement measuring technology of a kind of maturation, and owing to the correlation coefficient of two width images is insensitive to acoplanarity displacement, therefore Digital Image Correlation Method is applicable to the measurement of plane displacement distribution.
Above it can be seen that optical interferometry method is two kinds of different measurement technology from Digital Speckle Correlation Method, light path arranges difference, and measuring principle is the most different, measures the result obtained and emphasizes particularly on different fields, and height is wanted in the measurement sensitivity of interference technique, and the two seldom has common factor.For the interference fringe utilizing interference of light method to obtain, generally interference fringe image is carried out the analysis of phase-modulation and demodulation, and then obtains displacement field.There is presently no and be found to have research worker Applied Digital image correlation method and isolate in-plane displacement from two width interference fringe pictures, the most do not find to use digital correlation method to isolate acoplanarity displacement from two width interference fringe pictures.
Summary of the invention
In order to solve the shortcoming of prior art, the invention provides a kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, the method is applicable to dynamic interference fringe field, it is possible to process interference fringe field.
For achieving the above object, the present invention is by the following technical solutions:
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, including:
Step (1): the interference fringe image before collection deformation of body, as the first frame interference fringe image, gathers the interference fringe image after deformation of body as the second frame interference fringe image；
Step (2): the first frame interference fringe image and the second frame interference fringe image are carried out gray proces, extracts the fringe frequency of the first frame interference fringe image and uses sub-pix related algorithm to calculate the plane displacement distribution between the first frame interference fringe picture and the second frame interference fringe picture；
Step (3): the plane displacement distribution obtained according to step (2) and the fringe frequency of the first frame interference fringe image, and according to plane displacement distribution, the fringe frequency of the first frame interference fringe image and the relation of surface deformation phase place three that light stream basic form is set up, calculate the surface deformation phase information after asking for deformation of body.
Described step (1) utilize CCD to gather the interference fringe image before deformation of body and the interference fringe image after deformation of body.
Interference fringe in interference fringe image uses Michelson interference to obtain.
Described step (2) use window Fourier transform method extract the fringe frequency of the first frame interference fringe image.
Window function in window Fourier transform method uses Gaussian function.
In described step (2), employing window Fourier transform method extracts the process of the fringe frequency of the first frame interference fringe image, including:
First, by fringe frequency uniform discrete in its span of the first frame interference fringe image；
Then, the fringe frequency of uniform discrete is brought in the frequency-domain result that the first frame interference fringe image is corresponding after window Fourier transform respectively；
Finally, the fringe frequency of the maximum absolute value of the frequency-domain result corresponding after window Fourier transform so that the first frame interference fringe image is asked for, it is simply that need the fringe frequency of the first frame interference fringe image being extracted.
Described step (2) use sub-pix related algorithm based on gradient calculate the plane displacement distribution between the first frame interference fringe image and the second frame interference fringe image.
Phase place change between the first frame interference fringe image and the second frame interference fringe image in described step (1) is less than π.
The process using sub-pix related algorithm based on gradient to calculate the plane displacement distribution between the first frame interference fringe image and the second frame interference fringe image in described step (2) is:
Step (2.1): obtain the first frame interference fringe image after gray proces and the subregion image of the second frame interference fringe image moderate area opposite position respectively；
Step (2.2): the subregion image obtained in step (2.1) is calculated the first frame interference fringe image and the correlation coefficient of the second frame interference fringe image, and calculates the subregion the center displacement making correlation coefficient obtain maximum；
Step (2.3): using sub-pix related algorithm based on gradient to carry out choosing the first frame interference fringe image and the correlation coefficient of the second frame interference fringe image, recycling Taylor expansion asks for the Displacement of subregion the center displacement；
Step (2.4): be overlapped by the Displacement of subregion the center displacement with subregion the center displacement, obtains the plane displacement distribution between the first frame interference fringe image and the second frame interference fringe image.
Plane displacement distribution, the fringe frequency of the first frame interference fringe image in step (3) with the relation of surface deformation phase place three be: π times ,-the 2 of plane displacement distribution and the fringe frequency of the first frame interference fringe image and deformation time three's product are equal to surface deformation phase place.
The invention have the benefit that
(1) being correlated with based on digital picture of the present invention proposes a kind of method being extracted whole audience surface deformation phase place by the in-plane displacement between two width bar graphs, during the method is correlated with according to digital picture, sub-pix related algorithm based on gradient obtains the sports ground between two width images, make in-plane moving field and surface deformation phase place opening relationships according to optical flow field, and then obtain the surface deformation phase information of the whole audience between two two field pictures；
(2) this method only need to just can complete to deform the extraction of phase place in the spatial domain with two width bar graphs, without being transformed into frequency domain and Phase unwrapping operation, and it is the best in the effect of the most intensive extracted region phase place of striped, overcome the shortcoming that when striped is overstocked in existing phase demodulating method, demodulating error is bigger, also overcome the shortcoming that the calculating error caused owing to striped is sparse when using merely optical flow field Theoretical Calculation sports ground is excessive；The method process is simple, convenient, is suitable for interference of light kinetic measurement.
(3) compared with optical flow field Theoretical Calculation in-plane displacement method, except above-mentioned certainty of measurement advantage high, more practicality, use digital correlation algorithm to calculate in-plane displacement and also have two advantages: first, owing to its certainty of measurement is higher, this makes the effective coverage (standard regions) of data greatly expand.Optical flow field Theoretical Calculation in-plane displacement method can measure the acoplanarity displacement in image fringe frequency region between every pixel 0.3-0.7 radian, and the expanded range that the method for digital correlation algorithm calculating in-plane displacement can be measured has arrived about every pixel 0.13-0.8 radian, the scope of measurement improves more than 70%.Secondly as optical flow field Theoretical Calculation in-plane displacement method is carried out by pointwise iteration, expend long；And the method that digital correlation algorithm calculates in-plane displacement is by pointwise matching primitives displacement, the calculating time greatly reduces.
Accompanying drawing explanation
Fig. 1 is original interference striped simulation drawing；
Fig. 2 (a) is that additive phase isStriped simulation drawing after additive phase；
Fig. 2 (b) is that additive phase isStriped simulation drawing after additive phase；
Fig. 3 is that additive phase isTime the x direction optical flow field cross-sectional view at y=127 estimated；
Fig. 4 is to additive phaseThe normalization analog result extracted；
Fig. 5 (a) is to additive phaseThe normalization notional result extracted；
Fig. 5 (b) is to additive phaseThe analog result extracted；
Fig. 6 (a) is the initial interference bar graph that experiment obtains；
Fig. 6 (b) is the bar graph after loading deformation；
Fig. 7 is the experimental result picture of the present invention；
Fig. 8 is the object surface deformation Method for Phase Difference Measurement flow chart relevant based on digital picture of the present invention.
Detailed description of the invention
The present invention will be further described with embodiment below in conjunction with the accompanying drawings:
As shown in Figure 8, the object surface deformation Method for Phase Difference Measurement relevant based on digital picture of the present invention, including:
Step (1): the interference fringe image before collection deformation of body, as the first frame interference fringe image, gathers the interference fringe image after deformation of body as the second frame interference fringe image；
Step (2): the first frame interference fringe image and the second frame interference fringe image are carried out gray proces, extracts the fringe frequency of the first frame interference fringe image and uses sub-pix related algorithm to calculate the plane displacement distribution between the first frame interference fringe picture and the second frame interference fringe picture；
Step (3): the plane displacement distribution obtained according to step (2) and the fringe frequency of the first frame interference fringe image, and according to plane displacement distribution, the fringe frequency of the first frame interference fringe image and the relation of surface deformation phase place three that light stream basic form is set up, calculate the surface deformation phase information after asking for deformation of body.
(1) Digital-image correlation method two image motion field principle
The ultimate principle that digital picture is relevant is as follows: before and after deformation of body, on its surface, the movement of geometric point creates in-plane displacement, and the speckle pattern before and after deforming due to it is relevant, therefore can pass through related algorithm, geometric point corresponding before and after determining deformation of body, can directly obtain in-plane deformation field.The most frequently used calculating correlation formula is:
In formula, (x, y) for the image before deformation, (x, y) for the image after deformation for g for f.U Yu v is every whole pixel displacement on x direction and y direction on image.WithFor image region average gray.Formula (1) represent before being deformed after image on respectively take subregion that size is m*m to calculate correlation coefficient C, u and v that C can be made to take maximum is the displacement at subregion center.Pass through said method, it may be determined that the whole pixel displacement value of two width images.But, the shift value in the middle of reality is generally not and is exactly integer.
Along with the requirement of certainty of measurement is constantly improved by scientific research in recent years, application sub-pix searching algorithm obtains accurate Displacement becomes the important research direction that digital picture is relevant.Common sub-pixel recognition mainly has Newton.Raphson (N-R) iterative method, method based on gradient etc..In order to improve certainty of measurement, need to carry out further the calculating of Displacement on the basis of whole pixel result.
Calculation of correlation factor formula selected in sub-pix related algorithm based on gradient is:
In formula, u', v' are the Displacement corresponding to whole pixel displacement result.WillTaylor expansion, takes first approximation, and makesCan obtain:
Wherein
With x in formula, y is that lower target amount represents x, y are asked partial derivative.When calculating the differential in formula (3), what we selected is Barron gradient operator, and its computational methods are as follows:
Gradient method is in simulation experiment, and 0.001～0.01 Displacement precision is less than 0.005 pixel up to 0.001 pixel, 0.01～0.1 Displacement absolute error, and the relative error in 0.1～1.0 pixel coverages can control 2%.The sports ground Δ u=u+u' between two required width consecutive images and Δ v=v+v' can be tried to achieve according to above formula.
(2) extract body deformability phase place principle
(x, y) place's gray value is that (x, y, t), (t+ this point of Δ t) moment moves to new position, and (x+ Δ x, y+ Δ y), gray value is designated as I (x+ Δ x, y+ Δ y) to I to be located at t pixel.By I, (x+ Δ x, y+ Δ y, t+ Δ t) launches by Taylor's formula and ignores the high-order term of more than second order, has
Simultaneously according to image consistency it is assumed that i.e. I (x, y, (x+ Δ x, y+ Δ y, t+ Δ t), can obtain t)=I
IxΔu+IyΔv+It=0 (6)
WhereinIx、IyAnd ItIt being respectively image I for x, the partial derivative of y, t. formula (6) is the basic equation of light stream.And interference fringe picture typically can be expressed as:
Wherein a (x, y, t) be background light intensity, b (x, y, t) be the amplitude of bar graph,Phase information for bar graph.By function I, (x, y, t) at point (x0,y0) do Taylor series expansion, taking first approximation can obtain:
It is generally considered that a and b is constant.Therefore the basic equation of optical flow field (6) is represented by
WhereinFor point (x0,y0) knots modification of phase place within the Δ t time.Due to Wherein fx0And fy0Represent point (x0,y0) the horizontal and vertical fringe frequency at place.Therefore formula (9) can be written as again
Abbreviation formula (10) can obtain
Phase place change between two width interference fringe picturesDuring less than π, they are relevant and meet image consistency it is assumed that the motion of every sub regions selected by figure can approximate and regard translation of rigid body as, therefore the in-plane moving field Δ u of two width consecutive images and Δ v can try to achieve according to image correlation algorithm.Meanwhile, plane displacement distribution and surface deformation phase place are combined by formula (11), if obtaining horizontal and vertical frequency f of stripedx0And fy0, the variable quantity of the acoplanarity displacement phase place of interference fringe picture can be tried to achieve
The present invention uses method that window Fourier changes to obtain horizontal and vertical frequency f of stripedx0And fy0, and then solve the information of phase place.
(3) window Fourier transform
For extracting fringe frequency, introduce following window Fourier computing:
In formula (12), (ξ, η) is space a bit (x, y) corresponding frequency domain coordinates, Sf (μ, ν；ξ, η) it is I (x, y) result of corresponding frequency domain after window Fourier transform.(x, y) is window function to h, typically takes Gaussian functionσxAnd σyFor the standard deviation of Gauss distribution, they determine the size of window.Analysis from document [21]
Wherein (fx0,fy0) in order to make, | Sf (x, y, ξ, η) | takes (ξ, the η) of maximum, is also the laterally and longitudinally fringe frequency of every bit in interference fringe picture simultaneously.Therefore fringe frequency fx0And fy0Extracting method can be expressed as[23]: first have to, by fringe frequency (ξ, η) uniform discrete in its span of bar graph, then these values be brought into respectively | Sf (x, y, ξ, η) |, wherein can make | Sf (x, y, ξ, η) | take the point (f of maximumx0,fy0) it is the solution of formula (13), namely fringe frequency.Finally the fringe frequency tried to achieve is brought into formula (11) the deformation phase place from face can be tried to achieve.
(4) simulation and experimental result and analysis
According to formula (7), using Matlab Software Create one width interference fringe picture as original image, size is 203*203 pixel, as it is shown in figure 1, wherein a=0, b=1, PHASE DISTRIBUTION is
According to sampling thheorem, the maximum fringe frequency that piece image can be expressed is less than 0.5[21-24], therefore be [-0.5,0.5] by the range set of frequency (ξ, η) uniform discrete, the sampling interval takes Δ f=0.01.The σ of integration windowxAnd σyAll take 10 pixel sizes.
Extracting the fringe frequency (f of simulation drawingx0,fy0After), then bar graph is separately added intoStationary phase and
Deformation phase place.Why the size of selection deformation phase place isBeing because when in two width images, the deformation phase value of certain point is more than π, this point there will be the jumping phenomenon of black and white strip, thus causing the value of estimated motion vector u, v and last required phase place is zero.Therefore the span of the deformation phase place that can record in this method is [0, π].When deformation phase placeTime, the scope of its change is about (0,2 π/5), and the condition meeting this method limits requirement.Additive phaseBar graph obtained by rear is respectively shown in Fig. 2 (a) and Fig. 2 (b).
In using digital picture relevant, sub-pix related algorithm based on gradient carries out the measurement of sports ground between two width figures respectively to Fig. 1 and Fig. 2 (a) and (b), subregion window size takes 50*50 pixel, wherein Fig. 1 Yu Fig. 2 (a), i.e. addition of phase placeSectional view is as shown in Figure 3 at y=127 for rear estimated x direction sports ground.Making the time variation amount Δ t=1 between two width images, obtain the phase place added finally according to formula (11), i.e. deform phase information, its theoretical and that simulate normalization Comparative result such as Fig. 4, Fig. 5 (a), (b) are shown.
By Fig. 1 and Fig. 2 it will be seen that the central authorities of all interference fringe pictures are a bigger round speckle and the most sparse the closer to core striped, its fringe frequency is the lowest.Due to the least at striped the most intensive place motion vector, therefore the size Ying Shiyou center of sports ground estimated between the two images is to both sides monotone decreasing.
But as shown in Figure 3, the sports ground that this algorithm is estimated in fringe frequency lower can produce bigger error, the sports ground especially estimated at Yuan Ban center is 0, so the sports ground estimated between an a1 (x=86) and a2 (x=119) has bigger fluctuating, and the sports ground estimated at x<86 and x>119 is the most accurate.
Due to the existence of above-mentioned error, therefore there will be one " hole " depression equally, as shown in Fig. 4 and Fig. 5 (b) in analog result in the central authorities of two simulation drawings.
Fringe frequency absolute value corresponding at data analysis, a1 and a2 is 0.13, and i.e. under the subregion window of 50*50 pixel, the sports ground estimated when the absolute value of fringe frequency is more than 0.13 is ideal.Fringe frequency absolute value tends to a plane, i.e. additional phase place more than the phase place extracted at 0.13 in the diagramBeing a constant, this is consistent with theoretical value.Meanwhile, it is more than the theory at 0.13 with analog result contrast it can be seen that the phase place that the method is extracted is accurately according to Fig. 5 at fringe frequency absolute value.
Compared with optical flow field Theoretical Calculation in-plane displacement method, the present invention has certainty of measurement advantage high, more practicality, use digital correlation algorithm to calculate in-plane displacement and also have two advantages: first, owing to its certainty of measurement is higher, this makes the effective coverage (standard regions) of data greatly expand.Optical flow field Theoretical Calculation in-plane displacement method can measure the acoplanarity displacement in image fringe frequency region between every pixel 0.3-0.7 radian, and the expanded range that the method for digital correlation algorithm calculating in-plane displacement can be measured has arrived about every pixel 0.13-0.8 radian, the scope of measurement improves more than 70%.Secondly as optical flow field Theoretical Calculation in-plane displacement method is carried out by pointwise iteration, expend long；And the method that digital correlation algorithm calculates in-plane displacement is by pointwise matching primitives displacement, the calculating time greatly reduces.
(5) Data Processing in Experiment result and analysis
Michelson interference is used to obtain interference fringe, initial pictures is gathered by CCD, image size is 459 × 459 pixels, with piezoelectric ceramics phase-shifter, the disk that periphery is fixing is carried out center loaded deformation as shown in Fig. 6 (a), it is thus achieved that bar graph such as Fig. 6 (b) shown.Taking Δ t=1, the experimental result that using formula (11) obtains is as shown in Figure 7.
It will be seen in fig. 7 that the data result measured by Shi Yan is preferable, show that this algorithm is feasible.Be may certify that by simulation and experimental result, the phase place that the method obtains at the most intensive place of striped is the most accurate, overcomes the defect that in existing phase demodulating method, the closeest error of striped is the biggest completely.If additionally, the image processed is several width continually varying images, the time variation amount Δ t between every two two field pictures only need to be made to take the time interval between two two field pictures and can complete the dynamic quantitative extraction of interference fringe picture phase contrast.
The present invention propose a kind of by the in-plane displacement between two width bar graphs to extract the new method of whole audience surface deformation phase place, during the method is correlated with according to digital picture, sub-pix related algorithm based on gradient obtains the sports ground between two width images, then make in-plane moving field and surface deformation phase place opening relationships according to light stream fundamental equation, initial pictures fringe frequency and this sports ground carry out calculating and obtain surface deformation phase place.
This algorithm only just need to can complete the extraction of surface deformation phase place in the middle of spatial domain with two width bar graphs, eliminates and is transformed into frequency domain and Phase unwrapping operation, and process is simple, convenient, and the most accurate in the phase information of the most intensive extracted region of striped.The result of simulation and experiment shows, owing to image being caused no longer to have dependency relation when the phase changing capacity when between two width consecutive images is more than π and no longer meeting image consistency it is assumed that therefore the measurement scope of this deformation phase calculation method is [0, π].
As long as additionally, the time interval between learning two two field pictures in the video sequence can complete the extraction of interference of light kinetic measurement surface deformation phase place.The method is that interference of light kinetic measurement provides new approach.
Although the detailed description of the invention of the present invention is described by the above-mentioned accompanying drawing that combines; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme, those skilled in the art need not to pay various amendments or deformation that creative work can make still within protection scope of the present invention.
Claims (10)
1. the object surface deformation Method for Phase Difference Measurement being correlated with based on digital picture, it is characterised in that including:
Step (1): the interference fringe image before collection deformation of body is as the first frame interference fringe image, after gathering deformation of body
Interference fringe image as the second frame interference fringe image；
Step (2): the first frame interference fringe image and the second frame interference fringe image are carried out gray proces, extracts the first frame and does
Relate to the fringe frequency of stripe pattern and use sub-pix related algorithm to calculate the first frame interference fringe picture and the second frame interference fringe picture
Between plane displacement distribution；
Step (3): the plane displacement distribution obtained according to step (2) and the fringe frequency of the first frame interference fringe image, and
Plane displacement distribution, the fringe frequency of the first frame interference fringe image and the surface deformation phase place three set up according to light stream basic form
Relation, calculate the surface deformation phase information asked for after deformation of body.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, described step (1) utilize CCD to gather the interference fringe image before deformation of body and the interference fringe after deformation of body
Image.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, the interference fringe in interference fringe image uses Michelson interference to obtain.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, described step (2) use window Fourier transform method extract the fringe frequency of the first frame interference fringe image.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, the window function in window Fourier transform method uses Gaussian function.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, in described step (2), employing window Fourier transform method extracts the process of the fringe frequency of the first frame interference fringe image,
Including:
First, by fringe frequency uniform discrete in its span of the first frame interference fringe image；
Then, the fringe frequency of uniform discrete bring into respectively the first frame interference fringe image after window Fourier transform right
In the frequency-domain result answered；
Finally, the absolute value of the frequency-domain result corresponding after window Fourier transform so that the first frame interference fringe image is asked for
Big fringe frequency, it is simply that need the fringe frequency of the first frame interference fringe image being extracted.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, described step (2) uses sub-pix related algorithm based on gradient calculate the first frame interference fringe image and the second frame is done
Relate to the plane displacement distribution between stripe pattern.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, the phase place change between the first frame interference fringe image and the second frame interference fringe image in described step (1) is less than π.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature exists
In, described step (2) uses sub-pix related algorithm based on gradient calculate the first frame interference fringe image and the second frame is done
The process relating to the plane displacement distribution between stripe pattern is:
Step (2.1): obtain the first frame interference fringe image after gray proces and medium of the second frame interference fringe image respectively
The subregion image of long-pending opposite position；
Step (2.2): the subregion image obtained in step (2.1) is calculated the first frame interference fringe image and the second frame
The correlation coefficient of interference fringe image, and calculate the subregion the center displacement making correlation coefficient obtain maximum；
Step (2.3): use sub-pix related algorithm based on gradient to carry out choosing the first frame interference fringe image and the second frame is done
Relating to the correlation coefficient of stripe pattern, recycling Taylor expansion asks for the Displacement of subregion the center displacement；
Step (2.4): be overlapped by the Displacement of subregion the center displacement with subregion the center displacement, obtains the first frame
Plane displacement distribution between interference fringe image and the second frame interference fringe image.
A kind of object surface deformation Method for Phase Difference Measurement relevant based on digital picture, its feature
It is, the pass of plane displacement distribution, the fringe frequency of the first frame interference fringe image and surface deformation phase place three in step (3)
System is: π times ,-the 2 of plane displacement distribution and the fringe frequency of the first frame interference fringe image and deformation time three's product are equal to from face
Deformation phase place.
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Cited By (8)
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| CN109341548A (en) * | 2018-12-21 | 2019-02-15 | 福州大学 | Three-dimensional vibrating vision measurement system and method based on variable density striped |
| CN109413302A (en) * | 2018-09-07 | 2019-03-01 | 中国科学院国家空间科学中心 | A kind of dynamic interference fringe distortion correction method for pixel response frequency domain measurement |
| CN109540017A (en) * | 2018-11-26 | 2019-03-29 | 广东工业大学 | Cross section deformation system for measuring quantity in object |
| CN110033435A (en) * | 2019-03-06 | 2019-07-19 | 华中科技大学 | A kind of high-sensitivity digital picture displacement frequency-domain analysis method |
| CN110618028A (en) * | 2019-08-01 | 2019-12-27 | 杭州健途科技有限公司 | Tensile micro-stress detection method for performance degradation of fiber reinforced composite material |
| CN112665529A (en) * | 2021-01-19 | 2021-04-16 | 浙江理工大学 | Object three-dimensional shape measuring method based on stripe density area segmentation and correction |
| CN113063356A (en) * | 2021-03-05 | 2021-07-02 | 中国建筑材料科学研究总院有限公司 | Method for measuring material directional deformation out-of-plane displacement |
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| CN107367244A (en) * | 2017-07-21 | 2017-11-21 | 南京理工大学 | A kind of optimal striped sequence method of design twined based on time phase solution |
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| CN109413302A (en) * | 2018-09-07 | 2019-03-01 | 中国科学院国家空间科学中心 | A kind of dynamic interference fringe distortion correction method for pixel response frequency domain measurement |
| CN109413302B (en) * | 2018-09-07 | 2020-10-23 | 中国科学院国家空间科学中心 | Dynamic interference fringe distortion correction method for pixel response frequency domain measurement |
| CN109540017A (en) * | 2018-11-26 | 2019-03-29 | 广东工业大学 | Cross section deformation system for measuring quantity in object |
| CN109341548A (en) * | 2018-12-21 | 2019-02-15 | 福州大学 | Three-dimensional vibrating vision measurement system and method based on variable density striped |
| CN110033435A (en) * | 2019-03-06 | 2019-07-19 | 华中科技大学 | A kind of high-sensitivity digital picture displacement frequency-domain analysis method |
| CN110618028A (en) * | 2019-08-01 | 2019-12-27 | 杭州健途科技有限公司 | Tensile micro-stress detection method for performance degradation of fiber reinforced composite material |
| CN110618028B (en) * | 2019-08-01 | 2022-05-31 | 杭州健途科技有限公司 | Tensile micro-stress detection method for performance degradation of fiber reinforced composite material |
| CN112665529A (en) * | 2021-01-19 | 2021-04-16 | 浙江理工大学 | Object three-dimensional shape measuring method based on stripe density area segmentation and correction |
| CN112665529B (en) * | 2021-01-19 | 2022-06-24 | 浙江理工大学 | Object three-dimensional shape measuring method based on stripe density area segmentation and correction |
| CN113063356A (en) * | 2021-03-05 | 2021-07-02 | 中国建筑材料科学研究总院有限公司 | Method for measuring material directional deformation out-of-plane displacement |
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