CN109506592A - Object dimensional surface shape measurement method and device based on striped light stream - Google Patents
Object dimensional surface shape measurement method and device based on striped light stream Download PDFInfo
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Abstract
The invention discloses a kind of object dimensional surface shape measurement methods and device based on striped light stream, with light stream field method, it is only necessary to which object dimensional face shape can be obtained in two images.Method includes the following steps: simulation generates grating fringe, and project to the surface of testee；It acquires striped and deforms preceding and deformed pattern；The 3 d shape information of testee is calculated using striped optical flow field method.
Description
Technical Field
The disclosure relates to the field of object surface shape measurement, in particular to a method and a device for measuring a three-dimensional object surface shape based on stripe light flow.
Background
The three-dimensional surface shape measurement has wide application in the fields of target detection, product inspection, production and manufacture, cultural relic restoration and the like. The projection grating is a common measurement method at present, and has the characteristics of non-contact, high precision, simple experiment system and the like. The main method for measuring the surface shape of an object by using a projection grating is a phase demodulation method, which comprises the following steps: fourier transform profilometry, phase shift methods, and the like. The Fourier profilometry can carry out three-dimensional reconstruction only by collecting one or two deformation fringe patterns, realizes the measurement of the object profile, has the characteristics of high measurement speed, suitability for dynamic measurement and the like, but needs to filter out fundamental frequency components from frequency spectrums in the calculation process, so that a zero-order frequency spectrum is separated from a first-order frequency spectrum, noise is easily generated in the separation process, the extraction of the object profile is influenced, and the calculation is complex. The phase shift method has the characteristics of simple structure, high measurement sensitivity and the like, but phase unwrapping is required in the calculation process, and the calculation is relatively complex.
At present, a method for measuring the three-dimensional surface shape of an object by adopting a micro Fourier transform profile realizes high measurement speed, reduces the overlapping of frequency spectrums to a certain extent, but the overlapping of the frequency spectrums still exists in the calculation process. The method can effectively recover the height of the object, but needs to acquire a plurality of images, and has large data processing amount and complex calculation in the calculation.
In summary, an effective solution is not yet available for the problems of overlapping frequency spectrums, large data processing amount and complex calculation.
Disclosure of Invention
In order to overcome the defects of the prior art, the disclosure provides a method and a device for measuring the three-dimensional shape of an object based on stripe optical flow, and the three-dimensional shape of the object can be obtained by only two images by using an optical flow field method.
The technical scheme adopted by the disclosure is as follows:
a method for measuring the three-dimensional shape of an object based on stripe optical flow comprises the following steps:
simulating to generate grating stripes, and projecting the grating stripes onto the surface of a measured object;
collecting patterns before and after the deformation of the stripes;
and calculating the three-dimensional surface shape information of the measured object by adopting a fringe optical flow field method.
Further, the step of collecting the patterns before and after the deformation of the stripes comprises:
taking a water plane as a reference plane, projecting the simulated grating stripes onto the reference plane through a projector, and acquiring the stripe pattern which is not modulated by the surface of the object to be measured through a CCD camera to obtain a pattern before stripe deformation;
and placing the measured object on a reference plane, and acquiring the fringe pattern modulated by the surface of the measured object through a CCD camera to obtain a pattern after fringe deformation.
Further, the step of calculating the three-dimensional surface shape information of the measured object by using the fringe optical flow field method comprises the following steps:
obtaining the light intensity of the pattern before and after the stripe deformation;
processing the light intensity of the patterns before and after the stripe deformation by adopting an optical flow field iteration method to obtain an optical flow field velocity component between the two patterns before and after the stripe deformation;
and calculating the three-dimensional surface shape height of the measured object by using the velocity component u of the optical flow field and the cotangent function value of the grating projection angle.
Further, the method for obtaining the light intensity of the pattern before and after the stripe deformation comprises the following steps:
respectively arranging the projector and the CCD camera at equal distance with the reference plane, respectively measuring the distance from the projector and the CCD camera to the reference plane xoy and the distance between the projector and the CCD camera, and determining the projection angle of the grating;
before a measured object is placed on a reference plane, acquiring the light intensity of a pattern on the reference plane before the stripe is deformed;
after a measured object is placed on the reference plane, the stripes are modulated by the surface of the measured object to deform, and the light intensity of the pattern formed by the deformed stripes modulated by the surface of the measured object on the reference plane is collected.
Further, the method for calculating the optical flow field velocity component between the two patterns before and after the deformation of the stripe comprises the following steps:
constructing an Euler-Lagrange equation, and solving the values of two components u and v of the motion vector obtained after the n +1 th iteration of each point on the image by using a Gauss-Seidel method;
and (3) iterating the values of two components u and v of the motion vector obtained after the (n +1) th iteration of each point on the image to obtain the optical flow field velocity component between the two patterns before and after the stripe deformation.
Further, the method for calculating the three-dimensional surface shape height of the measured object comprises the following steps:
comparing the distance from the projector and the CCD camera to the reference plane xoy with the distance between the projector and the CCD camera to obtain a cotangent function value of the grating projection angle;
and multiplying the velocity vector of the optical flow motion field by the cotangent function value of the grating projection angle to obtain the three-dimensional surface shape height of the measured object.
Further, the grating stripes generated by the simulation are parallel stripes or irregular stripes.
An apparatus for measuring a three-dimensional shape of an object, the apparatus being used for implementing the method for measuring a three-dimensional shape of an object as described above, the apparatus comprising a processor, a projector and a CCD camera, wherein:
the projector is configured to project the grating stripes generated by the processor to the surface of the measured object;
the CCD camera is configured to collect patterns before and after the deformation of the stripes and transmit the patterns to the processor;
the processor is configured to simulate generation of grating stripes; and receiving patterns which are uploaded by the CCD camera before and after the deformation of the stripes, and calculating the three-dimensional surface shape information of the measured object by adopting a stripe optical flow field method.
Further, the treatment appliance is configured to:
obtaining the light intensity of the pattern before and after the stripe deformation;
processing the light intensity of the patterns before and after the stripe deformation by adopting an optical flow field iteration method to obtain an optical flow field velocity component between the two patterns before and after the stripe deformation;
and calculating the three-dimensional surface shape height of the measured object by using the velocity component u of the optical flow field and the cotangent function value of the grating projection angle.
Further, the projector and the CCD camera are positioned on the same horizontal plane
The beneficial effects of this disclosure are:
(1) the method comprises the steps of projecting grating stripes generated by a processor to the surface of an object through a projector, enabling the projected grating stripes to deform due to modulation of the object surface, collecting patterns before and after the stripes are deformed by a CCD (charge coupled device) camera, and calculating three-dimensional surface shape information of the measured object by adopting a stripe optical flow field method;
(2) the method adopts an optical flow field method, does not need zero-level frequency spectrum and first-level frequency spectrum separation, and can obtain the three-dimensional surface shape of the object only by two images; regular projection grid lines are not needed; the measurement sensitivity is high; the noise immunity is good, the calculation is simple, and the error caused by phase demodulation is reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the disclosure and together with the description serve to explain the application and not to limit the disclosure.
FIG. 1 is a block diagram of a three-dimensional surface shape measuring device of an object;
FIG. 2 is a flow chart of a method for measuring the three-dimensional shape of an object;
FIG. 3 is a schematic diagram of an exemplary optical path for measuring three-dimensional surface shape by a projected grating method;
FIG. 4a is a sample view of an original parallel stripe pattern;
FIG. 4b is a graphical representation of parallel stripes after modulation;
FIG. 4c is a spherical cap profile using parallel projected fringes;
fig. 4d is a graph of theoretical vs. calculated values for a cross-section x-256 using parallel projected fringes;
FIG. 5a is a projected pre-deformation irregular fringe pattern;
FIG. 5b is a graph of irregular fringes after modulation;
FIG. 5c is a diagram of a spherical cap profile using irregular projected fringes;
FIG. 5d is a graph of theoretical vs. calculated values for a spherical cap profile using irregular projected fringes over a cross-section x-256;
FIG. 6a is a fringe pattern before modulation of the mask;
FIG. 6b is a fringe pattern after modulation of the mask;
FIG. 6c is a mask profile phase plane distribution diagram;
FIG. 6d is a three-dimensional distribution diagram of the mask profile phase;
FIG. 7a is a fringe pattern before spherical crown shape modulation;
FIG. 7b is a fringe pattern after spherical crown shape modulation;
FIG. 7c is a three-dimensional phase distribution diagram of a spherical cap shape;
FIG. 7d is a spherical cap phase plane distribution plot;
FIG. 8a is a graph of noise fringes before modulation of a spherical cap shape containing noise;
FIG. 8b is a graph of noise fringes after modulation of a spherical cap shape containing noise;
FIG. 8c is a three-dimensional distribution diagram of the profile phase obtained from the noise fringes;
FIG. 8d is a profile phase plane plot from noise fringes;
FIG. 9a is a graph of pre-modulation fringes produced by simulation;
FIG. 9b is a modulated fringe pattern generated by simulation;
FIG. 9c is a diagram of theoretical values of the surface shape of an object;
FIG. 9d is a diagram illustrating the simulated values of the horizontal displacement vector field of the object surface shape;
fig. 9e is a diagram illustrating the simulated vertical displacement of the object surface.
Detailed Description
The present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
One or more embodiments provide a fringe light stream-based three-dimensional shape measurement device for an object, the device comprising a processor, a projector, and a CCD camera, wherein:
the projector is configured to project the grating stripes generated by the processor to the surface of the object;
the CCD camera is configured to collect patterns before and after the deformation of the stripes and transmit the patterns to the processor;
the processor configured to generate grating stripes, project the grating stripes onto the surface of the object by the projector; and receiving images which are uploaded by the CCD camera and acquired before and after the deformation of the stripes, and calculating the three-dimensional surface shape information of the measured object by adopting a stripe optical flow field method.
In this embodiment, the projector and the CCD camera are located on the same horizontal plane.
In the present embodiment, the treatment device is configured to:
obtaining the light intensity of the pattern before and after the stripe deformation;
processing the light intensity of the patterns before and after the stripe deformation by adopting an optical flow field iteration method to obtain an optical flow field velocity component between the two patterns before and after the stripe deformation;
and calculating the three-dimensional surface shape height of the measured object by using the velocity component u of the optical flow field and the cotangent function value of the grating projection angle.
As shown in fig. 1, in the device for measuring a three-dimensional shape of an object based on a fringe optical flow according to this embodiment, a projector projects grating fringes generated by a processor onto a surface of the object, the projected grating fringes are deformed due to modulation of the object surface, a CCD camera is used to collect patterns before and after the fringes are deformed, and a fringe optical flow field method is used to calculate information on the three-dimensional shape of the object to be measured. The object three-dimensional surface shape measuring device of the embodiment uses an optical flow field method, does not need separation of a zero-order frequency spectrum and a first-order frequency spectrum, can obtain the object three-dimensional surface shape only by two images, does not need regular projection grid lines, has high measuring sensitivity, good noise immunity and simple calculation, and reduces errors caused by phase demodulation.
One or more embodiments also provide a method for measuring the three-dimensional shape of the object based on the striped optical flow, which is implemented on the basis of the device for measuring the three-dimensional shape of the object as described above. As shown in fig. 2, the measuring method includes the steps of:
and S101, simulating to generate grating stripes, and projecting the grating stripes onto the surface of the measured object.
In this embodiment, the processor generates the grating stripes through Matlab simulation, and projects the generated grating stripes onto the surface of the object to be measured through the projector, and the grating stripes projected onto the surface of the object may be deformed due to the modulation of the object plane.
S102, collecting fringe patterns before and after modulation by the object to be measured.
FIG. 3 is a basic light path diagram for measuring the three-dimensional shape of an object by a projected grating method. And taking the xoy plane as a reference plane, projecting the grating fringe generated by the processor on the xoy plane through a projector, and placing an object on the xoy plane, wherein the projected fringe pattern can be deformed due to the surface modulation of the object. Therefore, a CCD camera is used to capture the pattern before and after the deformation of the fringes.
And S103, calculating the three-dimensional surface shape information of the measured object by adopting a fringe optical flow field method.
The optical flow field is mainly used for motion measurement and has the advantage of dynamic measurement. The method is applied to monitoring, dynamic sensing, homeland security, intelligent environment, intelligent robot and other aspects by detecting the sports field of the tested object.
The fringe optical flow field method has high measurement precision, and vibration amplitude which is 450 times smaller than that of a single image pixel measurement method can be accurately measured by using optical flow to carry out vibration measurement on a structural body. The optical flow is used for measuring the two-dimensional displacement field of the object, and the measurement precision is higher than that of an image correlation method. The fringe image is processed by using the optical flow, and the phase of the biological sample is recovered through high-precision measurement of the refractive index, so that the interference microscope cell system capable of quantitative measurement is realized. For the wave surface information in a lattice form obtained by a Shack-Hartmann wave-front sensor, in-plane phase information can be accurately obtained by using an optical flow method, and then wave surface information is recovered by using Zernike fitting. The spiral phase transformation and the two-step phase shift technology are combined, and the measurement of the out-of-plane displacement can be realized. By measuring the light stream formed by moving the stripes, the out-of-plane displacement measurement can be realized only by using two stripe patterns before and after deformation, and further the three-dimensional displacement field measurement is realized. If the fringes are photoelastic or RGB shadow moire, the modulation phase of interest can be obtained by using a multi-frame regularized optical flow algorithm.
In step 103, the specific implementation process of calculating the three-dimensional surface shape information of the measured object by using the fringe optical flow field method is as follows:
and calculating a motion field velocity vector u between two patterns before and after the stripe deformation by adopting an optical flow field iterative calculation method, and calculating the three-dimensional surface shape information of the measured object by utilizing the velocity component u of the optical flow field and a cotangent function value of a grating projection angle.
In FIG. 3, C is the projector position, P is the CCD camera position, the distance from the projector and CCD camera to the reference plane xoy is l, the distance between the projector and CCD camera is D, and D (x)0,y0) Is any point on the object to be measured. Before placing the measured object, at the moment t, the stripe pattern light intensity expression on the reference plane is:
I(x,t)＝a+bcos(2πfxx) (1)
where a is background light intensity, b is fringe contrast, fxAs stripes at the coordinate xFrequency.
After the object is placed, the stripes are modulated by the object surface to deform after delta t time. The expression of the light intensity of the fringe pattern after object plane modulation is as follows:
I′(x′,t+Δt)＝a+bcos(2πfxx′) (2)
for point D (x)0,y0) The projected point on the reference plane is a (x, y), and the corresponding point acquired by the CCD camera is a B (x ', y '), where x ' is x + Δ x. The expression (2) of the light intensity of the fringe pattern modulated by the object plane can also be expressed as:
I′(x′,t+Δt)＝a+bcos(2πfxx+2πfxΔx) (3)
the deformation phase of the fringes is:
where Δ x is the coordinate change amount.
According to the geometric relationship, the three-dimensional surface shape height of the object to be measured is as follows:
because of the fact thatTherefore, d in the formula (5) can be ignored, so that the three-dimensional surface shape height of the object to be measured is:
wherein l is the distance from the projector and the CCD camera to the reference plane xoy; d is the distance between the projector and the CCD camera.
The formula (4) and the formula (6) can show that the three-dimensional surface shape height of the object to be measured is as follows:
wherein,α is the angle between the projected light and the viewing direction, i.e. the projection angle of the grating,is the phase of deformation of the fringes, fxIs the fringe frequency at coordinate x.
The stripe pattern light intensity I '(x', t + delta t) modulated by the object surface is subjected to Taylor series expansion at (x, y) and first-order approximation is taken, so that a stripe light stream phase equation can be obtained:
wherein,the optical flow vectors in the x and y directions, respectively, (x, y).
Since the projected is regular parallel stripes, thenEquation (8) can also be expressed as:
because of the fact thatfxIs the fringe frequency of the (x, y) point. Equation (9) can be expressed as:
wherein,in comparison with equation (10), Δ x is u · Δ t.
Fourier transform is carried out on the fringe image before modulation of the object to obtain the fringe frequency fxCalculating two fringe patterns before and after deformation by adopting an optical flow field iteration method to obtain a velocity vector u of an optical flow motion field, namely obtaining a deformation phase of the whole fieldThereby obtaining the three-dimensional surface shape of the object. More conveniently, the height of the three-dimensional surface shape of the object to be measured can be obtained through the formula (7) and the formula (10): :
wherein, the cta α is a projection angle α cotangent function value.
Therefore, the specific steps of calculating the three-dimensional surface shape information of the measured object by adopting the fringe optical flow field method comprise:
s103-1, obtaining the light intensity of the pattern before and after the stripe deformation.
Respectively arranging the projector and the CCD camera at equal distance with the reference plane, respectively measuring the distance from the projector and the CCD camera to the reference plane xoy and the distance between the projector and the CCD camera, and determining the projection angle of the grating;
before a measured object is placed on a reference plane, acquiring the light intensity of a pattern on the reference plane before the stripe is deformed;
after a measured object is placed on the reference plane, the stripes are modulated by the surface of the measured object to deform, and the light intensity of the pattern formed by the deformed stripes modulated by the surface of the measured object on the reference plane is collected.
S103-2, processing the light intensity of the patterns before and after the stripe deformation by adopting an optical flow field iteration method to obtain an optical flow field velocity component u between the two patterns before and after the stripe deformation.
In this embodiment, a Horn-Schunck algorithm, abbreviated as HS algorithm, is selected, and the basic idea is to require that the optical flow itself be as smooth as possible. By smoothing, it is within a given neighborhoodAs small as possible. Therefore, the HS algorithm resolves the calculation of the optical flow u, v to the minimum for equation (12), expressed as:
corresponding Euler-Lagrange equations can be obtained, a Gauss-Seidel method is used for solving, and the (n +1) th iterative estimation (un +1, vn +1) of each position on the image is obtained as follows:
un+1＝un-Ix[(Ixun+Iyvn+It)]/(α2+Ix 2+Iy 2) (13)
vn+1＝vn-Iy[(Ixun+Iyvn+It)]/(α2+Ix 2+Iy 2) (14)
ix, Iy and It are respectively partial derivatives of an image I to x, y and t, wherein I is a gray value at a pixel point (x, y) at the time t, un +1 and vn +1 are values of two components u and v of a motion vector obtained after n +1 th iteration of each point of the image, namely a motion vector field between two images, un and vn are values of two components u and v of the motion vector obtained after n th iteration of each point of the image, and α is a smoothing parameter.
The u and v obtained by iteration according to equation (13) and equation (14) are motion vectors between two images.
S103-3, calculating a cotangent function value of the projection angle of the grating.
And comparing the distance from the projector and the CCD camera to the reference plane xoy with the distance between the projector and the CCD camera, and taking a derivative to obtain a cotangent function value of the grating projection angle.
And S103-4, calculating the three-dimensional surface shape height of the measured object according to the formula (11) by using the velocity component u of the optical flow field and the cotangent function value of the grating projection angle.
According to the embodiment, the velocity vector u of the vector motion field can be obtained according to an optical flow field iteration method, and the three-dimensional surface shape height of the object to be measured can be obtained by multiplying the cotangent function value of the grating projection angle by the velocity vector u.
In the method for measuring the surface shape of the object based on the stripe optical flow, the grating stripes are projected on the surface of the object, the stripes are deformed due to the modulation of the object surface, and the direct optical flow field information of two stripe patterns is calculated through a stripe optical flow algorithm, so that the surface shape of the object is obtained. The method uses an optical flow field method, does not need zero-order frequency spectrum and first-order frequency spectrum separation, and can obtain the three-dimensional surface shape of the object only by two images; regular projection grid lines are not needed; the measurement sensitivity is high; the noise immunity is good, the calculation is simple, and the error caused by phase demodulation is reduced.
The embodiment provides simulation verification of an object three-dimensional surface shape measuring method based on stripe optical flow, and the specific process of the simulation verification is as follows:
(1) spherical cap surface shape measurement simulation by utilizing parallel projection stripes
A pattern of grating stripes of 512 x 512 pixels size is generated by Matlab simulation according to equation (1) and projected on the reference plane xoy plane, as shown in fig. 4a, as parallel stripes. Wherein a is 0, b is 1, fx0.4. The simulated object surface is a spherical cap of the table tennis ball, the radius R of the table tennis ball is 20mm, and the height h of the spherical cap ismax10mm, the angle between the projection light and the viewing directionThe fringe pattern is projected onto the spherical cap surface and is modulated by the object plane to be deformed, as shown in fig. 4 b.
If the observation distance is far greater than the size of the object plane, that is, the influence of the observation angle on the result is not considered, an iterative method is used to calculate the optical flow motion vector u, and at this time, the three-dimensional surface shape distribution of the object can be obtained according to the formula (11) with the smoothing factor of 1 and the iteration number of 350, as shown in fig. 4 c. Fig. 4d is a cross section comparing the calculated value with the theoretical value of the loaded surface shape, and it can be seen from fig. 4d that the spherical cap shape measured by the optical flow field algorithm is very well matched with the theoretical value. It is possible to measure the surface shape of the three-dimensional object by using the optical flow field method.
(2) And (4) utilizing the spherical crown shape measurement simulation of the irregular projection stripes.
Irregular fringe patterns are generated by matlab simulation and projected on the reference plane xoy plane, as shown in fig. 5 a. After the irregular stripes are projected on the surface of the object, the irregular stripes are further deformed after being modulated by the surface of the object, as shown in fig. 5 b.
For convenient comparison, the radius R of the table tennis ball in simulation is 20mm, and the height h of the spherical capmax10mm, the angle between the projection light and the viewing directionAn optical flow field method is used to calculate an optical flow motion vector u, and the three-dimensional surface distribution of the loaded object can be obtained by the formula (11), as shown in fig. 5 c. The resulting calculated values were compared to a cross-section of the theoretical values, as shown in fig. 5 d. It can be seen thatThe measurement results obtained with irregular projected fringes fit well with the theoretical values. It can be seen that the optical flow field method is used for measuring the surface shape of an object, has no strict requirement on the projected stripes, is not limited to the parallel sinusoidal stripes, and can also be used for measuring the three-dimensional surface shape of the object by utilizing the irregular stripes.
One or more embodiments also provide experimental verification of the method for measuring the three-dimensional shape of the object based on the striped optical flow, and the experimental verification specifically comprises the following processes:
(1) experiment for measuring three-dimensional surface shape of object
In order to verify the feasibility of the above method for measuring the three-dimensional surface shape of an object based on a fringe optical flow and the correctness of the simulation result, the embodiment measures the surface shape of the object according to the experimental optical path diagram of fig. 3, and further performs experimental verification.
The mask is selected as the object to be measured, and the CCD camera is used to collect the fringe patterns before and after modulation by the object, as shown in FIG. 6a and FIG. 6 b.
The collected images of fig. 6a and fig. 6b before and after modulation are respectively processed by an optical flow field method, so as to obtain a three-dimensional surface-shaped phase distribution pattern of the object, as shown in fig. 6c and fig. 6 d. According to experimental results, the three-dimensional shape of the object can be calculated by using the projection grating through an optical flow field method.
(2) Verifying the application range of optical flow field
The measured object is the spherical cap of the table tennis, and the projected stripes are parallel stripes. The acquired fringe images before and after modulation of the object are shown in fig. 7a and 7 b. At this time, the deformed phase of the modulation fringes does not exceed pi. The spherical cap shape can be obtained by using the optical flow field method, as shown in fig. 7c and 7 d. The light field distribution around the spherical cap is changed due to the influence of the light reflected by the spherical cap in the projection process, so that the light field around the table tennis is not a plane. When the projection angle is changed, and the deformation phase of the modulation fringes is larger than pi, the optical flow oscillation phenomenon occurs, and the correct surface shape phase cannot be obtained. Therefore, the range of the phase value of the three-dimensional surface shape which can be measured by the optical flow field method is [0, pi ].
(3) Noise fringe experiment
When the optical flow field method is used for calculating the three-dimensional shape of the object, the method is insensitive to noise contained in the projection stripes and has no influence on the measurement of the three-dimensional shape of the object. Experimental verification was performed on this example. In the experiment, the measured object is a table tennis crown, the projected stripes are parallel stripe images of 512 × 512 pixels, and salt and pepper noise with the noise density of 0.05 is added to the parallel stripe images. The fringe images before and after modulation of the object surface are shown in fig. 8a and 8 b. The results of calculating the three-dimensional shape of the object by the optical flow field method are shown in fig. 8c and 8 d. It can be seen that when the optical flow field method is used for measuring the three-dimensional surface shape of an object, the method is insensitive to noise, and the noise has no influence on the measurement of the optical flow field surface shape.
One or more embodiments also provide surface shape measurement sensitivity analysis and verification of the fringe optical flow-based object three-dimensional surface shape measurement method, and the verification specifically comprises the following processes:
in this embodiment, the processor generates parallel stripes as shown in fig. 9a through Matlab simulation, loads a tiny profile to the parallel stripes to obtain a modulated stripe pattern as shown in fig. 9b, where the phase of the loaded profile is
The phase three-dimensional pattern loaded with the minute facets is shown in fig. 9 c.
Calculating the two fringe images by using an optical flow field method, and obtaining a horizontal displacement vector u of the fringe image by using an iteration method, wherein the sensitivity of the horizontal displacement vector u is 10-14nm, the number of iterations is 1000. The sensitivity of measuring the horizontal direction displacement delta x of the stripe by using an optical flow field method is 10 which can be obtained by changing delta x into-u.delta t-14nm, the result after filtering is shown in FIG. 9 d. For the displacement in the vertical direction, the sensitivity of calculating the vertical direction displacement h of the stripe by the optical flow field method is also 10 as shown in the formula (11)-14nm, e.g.As shown in fig. 9 e.
The method for measuring the three-dimensional surface shape of the object based on the stripe optical flow, which is provided by the embodiment, obtains the surface shape of the object by performing optical flow calculation on two stripe images before and after modulation, is simple in calculation method, does not need to be converted into frequency domain and phase demodulation operation, and is suitable for dynamic measurement. Simulation and experiment results show that the optical flow field method is feasible for recovering the surface shape of the object, and the phase range of the measured surface shape is 0, pi](ii) a The optical flow method is used for measuring the surface shape, no special requirement is made on the stripes, and the three-dimensional surface shape of the object can be measured by utilizing the irregular stripes; the method is insensitive to noise, and the noise in the projection stripes does not influence the measurement of the surface shape. Moreover, the sensitivity of the optical flow surface shape measuring method is high, and the simulation shows that the measuring sensitivity in the horizontal direction and the vertical direction is 10-14nm, so the optical flow field method is very suitable for measuring the tiny appearance of the micro-fluctuation.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.
Claims (10)
1. A method for measuring the three-dimensional surface shape of an object based on stripe optical flow is characterized by comprising the following steps:
simulating to generate grating stripes, and projecting the grating stripes onto the surface of a measured object;
collecting patterns before and after the deformation of the stripes;
and calculating the three-dimensional surface shape information of the measured object by adopting a fringe optical flow field method.
2. The method for measuring the three-dimensional shape of an object based on the striped optical flow as claimed in claim 1, wherein the step of collecting the patterns before and after the stripe deformation comprises:
taking a water plane as a reference plane, projecting the simulated grating stripes onto the reference plane through a projector, and acquiring the stripe pattern which is not modulated by the surface of the object to be measured through a CCD camera to obtain a pattern before stripe deformation;
and placing the measured object on a reference plane, and acquiring the fringe pattern modulated by the surface of the measured object through a CCD camera to obtain a pattern after fringe deformation.
3. The method for measuring the three-dimensional shape of an object based on the fringe optical flow as claimed in claim 1, wherein the step of calculating the three-dimensional shape information of the object to be measured by the fringe optical flow field method comprises:
obtaining the light intensity of the pattern before and after the stripe deformation;
processing the light intensity of the patterns before and after the stripe deformation by adopting an optical flow field iteration method to obtain an optical flow field velocity component between the two patterns before and after the stripe deformation;
and calculating the three-dimensional surface shape height of the measured object by using the velocity component u of the optical flow field and the cotangent function value of the grating projection angle.
4. The method for measuring the three-dimensional shape of an object based on the striped optical flow as claimed in claim 3, wherein the method for obtaining the light intensity of the patterns before and after the stripe deformation comprises:
respectively arranging the projector and the CCD camera at equal distance with the reference plane, respectively measuring the distance from the projector and the CCD camera to the reference plane xoy and the distance between the projector and the CCD camera, and determining the projection angle of the grating;
before a measured object is placed on a reference plane, acquiring the light intensity of a pattern on the reference plane before the stripe is deformed;
after a measured object is placed on the reference plane, the stripes are modulated by the surface of the measured object to deform, and the light intensity of the pattern formed by the deformed stripes modulated by the surface of the measured object on the reference plane is collected.
5. The method for measuring the three-dimensional shape of an object based on the striped optical flow as claimed in claim 3, wherein the method for calculating the optical flow field velocity component between the two patterns before and after the stripe deformation comprises:
constructing an Euler-Lagrange equation, and solving the values of two components u and v of the motion vector obtained after the n +1 th iteration of each point on the image by using a Gauss-Seidel method;
and (3) iterating the values of two components u and v of the motion vector obtained after the (n +1) th iteration of each point on the image to obtain the optical flow field velocity component between the two patterns before and after the stripe deformation.
6. The method for measuring the three-dimensional shape of an object based on the striped optical flow according to claim 3, wherein the method for calculating the height of the three-dimensional shape of the measured object comprises:
comparing the distance from the projector and the CCD camera to the reference plane xoy with the distance between the projector and the CCD camera to obtain a cotangent function value of the grating projection angle;
and multiplying the velocity vector of the optical flow motion field by the cotangent function value of the grating projection angle to obtain the three-dimensional surface shape height of the measured object.
7. The method for measuring the three-dimensional shape of an object based on the striped optical flow as claimed in claim 1, wherein the simulated grating stripes are parallel stripes or irregular stripes.
8. An apparatus for measuring a three-dimensional shape of an object, which is used for implementing the method for measuring a three-dimensional shape of an object according to any one of claims 1 to 7, comprising a processor, a projector and a CCD camera, wherein:
the projector is configured to project the grating stripes generated by the processor to the surface of the measured object;
the CCD camera is configured to collect patterns before and after the deformation of the stripes and transmit the patterns to the processor;
the processor is configured to simulate generation of grating stripes; and receiving patterns which are uploaded by the CCD camera before and after the deformation of the stripes, and calculating the three-dimensional surface shape information of the measured object by adopting a stripe optical flow field method.
9. The apparatus of claim 8, wherein the processing device is configured to:
obtaining the light intensity of the pattern before and after the stripe deformation;
processing the light intensity of the patterns before and after the stripe deformation by adopting an optical flow field iteration method to obtain an optical flow field velocity component between the two patterns before and after the stripe deformation;
and calculating the three-dimensional surface shape height of the measured object by using the velocity component u of the optical flow field and the cotangent function value of the grating projection angle.
10. The apparatus for measuring the three-dimensional shape of an object as claimed in claim 8, wherein the projector and the CCD camera are located on the same horizontal plane.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110160459A (en) * | 2019-06-06 | 2019-08-23 | 山东师范大学 | Based on the method for improving light stream field theory extraction speckle interference fringe pattern deformation phase |
| CN110360954A (en) * | 2019-08-14 | 2019-10-22 | 山东师范大学 | A kind of surface shape measurement method and system based on spatial coordinates calculation |
| CN111426284A (en) * | 2020-04-10 | 2020-07-17 | 山东师范大学 | Brox optical flow estimation-based surface shape measurement error correction method and system |
| CN111912356A (en) * | 2020-06-29 | 2020-11-10 | 山东师范大学 | Method and device for measuring three-dimensional surface shape of object based on L-K local optical flow |
| CN112229342A (en) * | 2020-09-14 | 2021-01-15 | 桂林电子科技大学 | Rapid self-correction method for projection grating in phase measurement profilometry |
| CN113720268A (en) * | 2021-08-03 | 2021-11-30 | 西安交通大学 | Digital moire method, system, equipment and storage medium for measuring strain based on light intensity principle |
| CN114347064A (en) * | 2022-01-31 | 2022-04-15 | 深圳市云鼠科技开发有限公司 | Robot collision detection method and device based on optical flow, computer equipment and storage medium |
| CN116990320A (en) * | 2023-09-27 | 2023-11-03 | 江西驰宇光电科技发展有限公司 | Dark field imaging method and device for defect detection |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007183290A (en) * | 1999-04-12 | 2007-07-19 | Fujitsu Ltd | Image measuring method, image measuring device, and image measuring program storage medium |
| CN103047944A (en) * | 2013-01-22 | 2013-04-17 | 廖怀宝 | Three-dimensional object measuring method and device |
| CN104697468A (en) * | 2015-03-30 | 2015-06-10 | 南昌航空大学 | Optical three-dimensional measurement method based on tilted phase encoding stripes |
| CN105043283A (en) * | 2015-07-08 | 2015-11-11 | 山东师范大学 | Method for carrying out object deformation phase measurement by using optical flow field |
| CN105953747A (en) * | 2016-06-07 | 2016-09-21 | 杭州电子科技大学 | Structured light projection full view three-dimensional imaging system and method |
| CN106289109A (en) * | 2016-10-26 | 2017-01-04 | 长安大学 | A kind of three-dimensional reconstruction system based on structure light and method |
-
2018
- 2018-12-13 CN CN201811524845.5A patent/CN109506592A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007183290A (en) * | 1999-04-12 | 2007-07-19 | Fujitsu Ltd | Image measuring method, image measuring device, and image measuring program storage medium |
| CN103047944A (en) * | 2013-01-22 | 2013-04-17 | 廖怀宝 | Three-dimensional object measuring method and device |
| CN104697468A (en) * | 2015-03-30 | 2015-06-10 | 南昌航空大学 | Optical three-dimensional measurement method based on tilted phase encoding stripes |
| CN105043283A (en) * | 2015-07-08 | 2015-11-11 | 山东师范大学 | Method for carrying out object deformation phase measurement by using optical flow field |
| CN105953747A (en) * | 2016-06-07 | 2016-09-21 | 杭州电子科技大学 | Structured light projection full view three-dimensional imaging system and method |
| CN106289109A (en) * | 2016-10-26 | 2017-01-04 | 长安大学 | A kind of three-dimensional reconstruction system based on structure light and method |
Non-Patent Citations (1)
| Title |
|---|
| 赵冉等: ""基于光流场理论测量物体变形相位的新方法"", 《光电子 激光》 * |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110160459A (en) * | 2019-06-06 | 2019-08-23 | 山东师范大学 | Based on the method for improving light stream field theory extraction speckle interference fringe pattern deformation phase |
| CN110360954B (en) * | 2019-08-14 | 2021-05-04 | 山东师范大学 | Surface shape measuring method and system based on space coordinate calculation |
| CN110360954A (en) * | 2019-08-14 | 2019-10-22 | 山东师范大学 | A kind of surface shape measurement method and system based on spatial coordinates calculation |
| CN111426284A (en) * | 2020-04-10 | 2020-07-17 | 山东师范大学 | Brox optical flow estimation-based surface shape measurement error correction method and system |
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| CN112229342A (en) * | 2020-09-14 | 2021-01-15 | 桂林电子科技大学 | Rapid self-correction method for projection grating in phase measurement profilometry |
| CN112229342B (en) * | 2020-09-14 | 2022-06-03 | 桂林电子科技大学 | Rapid self-correction method for projection grating in phase measurement profilometry |
| CN113720268A (en) * | 2021-08-03 | 2021-11-30 | 西安交通大学 | Digital moire method, system, equipment and storage medium for measuring strain based on light intensity principle |
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| CN114347064B (en) * | 2022-01-31 | 2022-09-20 | 深圳市云鼠科技开发有限公司 | Robot collision detection method and device based on optical flow, computer equipment and storage medium |
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