Three-dimensional measurement method for moving object

Abstract

The invention provides a three-dimensional measurement method for a moving object, which comprises the following steps of: projecting a frame of color image to an object to be measured by a projection light source, capturing a color distortion fringe pattern containing object information by using a camera, and separating two frames of phase shift fringes of an R channel and a B channel of the color distortion fringe pattern based on a color separation technology; removing the background intensity of the two frames of phase shift fringe images through empirical mode decomposition, and obtaining two frames of normalized phase shift fringe images; extracting phase distribution of the normalized two frames of phase shift fringe patterns through Schmidt orthogonalization; and reconstructing the three-dimensional shape of the object according to the phase distribution of the two normalized frames of phase shift fringe patterns. By applying the technical scheme of the invention, the technical problem of low measurement precision of the Fourier single-frame method in the prior art can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional measurement, and particularly to a three-dimensional measurement method for a moving object. Background Art

[0002] The structured light three-dimensional measurement technology based on digital fringe projection has been widely used in the fields of industrial inspection, aerospace, face detection, security industry, etc. due to its advantages of non-contact, high precision, high reliability, low cost, etc. With the development of technology, in practical applications, the objects to be measured are no longer limited to static objects, and the high-precision three-dimensional measurement of moving objects has become an urgent need. The structured light three-dimensional measurement technology based on digital fringe projection can be divided into single-frame measurement methods and multi-frame measurement methods. As one of the most commonly used single-frame measurement technologies, Fourier profilometry has the advantage that the three-dimensional shape of an object can be reconstructed using a single fringe pattern, which is suitable for the field of rapid three-dimensional measurement. However, due to the limitation of filtering, for objects with complex surface shapes, its measurement accuracy is relatively low. Phase-shifting profilometry is one of the most typical three-dimensional measurement methods in multi-frame measurement methods. It reconstructs the three-dimensional shape of an object by projecting a series of fringe patterns onto the surface of the object to be measured. However, it requires at least three fringe patterns, and for the measurement of moving objects, since the phase shift amount between adjacent fringe patterns is unknown, it will lead to measurement errors. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0004] The present invention provides a three-dimensional measurement method for a moving object. The three-dimensional measurement method for the moving object includes: a projection light source projects a frame of color image onto the object to be measured, a camera captures a color distorted fringe pattern containing object information, and two frames of phase-shifted fringes in the R channel and the B channel of the color distorted fringe pattern are separated based on color separation technology; empirical mode decomposition is used to remove the background intensity of the two frames of phase-shifted fringe images to obtain two normalized frames of phase-shifted fringe patterns; Schmidt orthogonalization is used to extract the phase distribution of the two normalized frames of phase-shifted fringe patterns; the three-dimensional shape of the object is reconstructed according to the phase distribution of the two normalized frames of phase-shifted fringe patterns.

[0005] Further, the expression of the color distorted fringe pattern after color separation is and where I 1 (x,y) and I 2 (x,y) respectively represent the light intensity distributions of the two frames of phase-shifted fringes separated from the color distorted image; a 1 (x,y) and a 2 (x,y) respectively represent the fringe patterns I 1 (x,y) and I 2The background intensity of (x,y), a 1 (x,y) ≠ a 2 (x,y); b 1 (x,y) and b 2 (x,y) are respectively the fringe pattern I 1 (x,y) and I 2 The modulation degree of (x,y), b 1 (x,y) ≠ b 2 (x,y); is the phase distribution of the object to be measured; δ is the phase shift amount between two frames of phase-shifted fringe patterns.

[0006] Furthermore, for the separated phase-shifted fringe pattern I 1 (x,y) or I 2 The specific steps of applying empirical mode decomposition to (x,y) include:

[0007] (1) Initialization, let f 0 (x,y) = I 1 (x,y), i = 1, or, let f 0 (x,y) = I 2 (x,y), i = 1;

[0008] (2) Obtain the i-th order two-dimensional intrinsic mode function:

[0009] 1) Initialization, let k = 0, H k (x,y) = f i-1 (x,y),

[0010] 2) Find all the maximum and minimum points of H k (x,y),

[0011] 3) Use the cubic spline interpolation function to interpolate the maximum and minimum points respectively to obtain the upper envelope surface E max (x,y) and the lower envelope surface E min (x,y),

[0012] 4) Take the mean of the upper and lower envelopes:

[0013]

[0014] where, M k (x,y) is the mean envelope,

[0015] 5) Subtract the mean envelope from the signal to obtain the residue:

[0016] H k+1 (x,y) = H k (x,y) - M k (x,y)

[0017] Among them, H k+1 (x, y) is the remainder after removing the mean envelope,

[0018] 6) Determine whether the obtained remainder meets the BIMF condition through the standard deviation. If the standard deviation value is less than the threshold, the obtained remainder can be used as a BIMF component. Let IMF i (x, y) = H k+1 (x, y), and then go to step 7); otherwise, replace k with k + 1 and go back to step 2) to continue the process.

[0019] 7) Obtain the i-th order residual component:

[0020] res i (x, y) = res i-1 (x, y) - IMF i (x, y)

[0021] Among them, res i (x, y) is the i-th order residual component, and res i-1 (x, y) is the (i - 1)-th order residual component. If the number of extreme points in the i-th order residual component res i (x, y) is not zero, then replace i with i + 1, take res i (x, y) as a new initial signal, and then go to step 2); otherwise,

[0022] The decomposition process ends.

[0023] Furthermore, the standard deviation in step 6) is defined as Among them, s d is the standard deviation, and n and m respectively represent the number of rows and columns of the fringe pattern.

[0024] Furthermore, the BIMF condition is:

[0025] (1) The difference between the number of extreme points and the number of zero crossings should not exceed 1 at most;

[0026] (2) In the local area, the mean values of the upper envelope formed by all maxima and the lower envelope formed by all minima are zero.

[0027] Furthermore, the phase distribution Among them, I′ 1 and I′ 2 are respectively the two-frame phase-shifted fringe patterns after normalization, <·> represents the inner product operator; ‖·‖ represents the two-norm.

[0028] Furthermore, according to Reconstruct the three-dimensional shape of an object, where h(x, y) is the three-dimensional shape data of the object, L represents the height from the camera to the object in the three-dimensional imaging system; d is the distance from the projection light source to the camera; and f is the frequency of the fringe pattern.

[0029] Applying the technical solution of the present invention, a three-dimensional measurement method for a moving object is provided. In this three-dimensional measurement method for a moving object, two frames of phase-shifted fringes are encoded in the R and B channels of the projection light source, and color separation technology is used to separate the single-frame color distorted fringe pattern obtained by the camera. The uneven background intensity of the two frames of fringe patterns is removed by empirical mode decomposition technology, and the phase information of the object is extracted by Schmidt orthogonalization. The present invention overcomes the limitation of the low measurement accuracy of the Fourier single-frame method and has the advantages of strong robustness and fast measurement. Compared with the prior art, the technical solution of the present invention can solve the technical problem of the low measurement accuracy of the Fourier single-frame method in the prior art. Description of the Drawings

[0030] The accompanying drawings included are used to provide a further understanding of the embodiments of the present invention, which form a part of the specification, illustrate the embodiments of the present invention, and together with the written description, explain the principles of the present invention. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0031] Figure 1 A schematic flowchart of the three-dimensional measurement method for a moving object provided according to a specific embodiment of the present invention is shown. Detailed Embodiments

[0032] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. The description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] Unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods, and devices should be regarded as part of the specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0035] As Figure 1 shown, a three-dimensional measurement method for a moving object is provided according to a specific embodiment of the present invention. The three-dimensional measurement method for the moving object includes:

[0036] A projection light source projects a frame of color image onto an object to be measured, a camera is used to capture a color distorted fringe pattern containing object information, and two frames of phase-shifted fringes in the R channel and B channel of the color distorted fringe pattern are separated based on color separation technology;

[0037] Empirical mode decomposition is used to remove the background intensity of the two frames of phase-shifted fringe images, and two normalized frames of phase-shifted fringe patterns are obtained;

[0038] The phase distribution of the two normalized frames of phase-shifted fringe patterns is extracted by Schmidt orthogonalization;

[0039] The three-dimensional shape of the object is reconstructed according to the phase distribution of the two normalized frames of phase-shifted fringe patterns.

[0040] Using this configuration method, a three-dimensional measurement method for a moving object is provided. In this three-dimensional measurement method for a moving object, two frames of phase-shifted fringes are encoded in the R and B channels of a projection light source. The single-frame color distorted fringe pattern acquired by the camera is separated using color separation technology. The uneven background intensity of the two frames of fringe patterns is removed by empirical mode decomposition technology, and the phase information of the object is extracted using Schmidt orthogonalization. The present invention overcomes the limitation of the low measurement accuracy of the Fourier single-frame method and has the advantages of strong robustness and fast measurement.

[0041] Further, in the present invention, first, a projection light source projects a frame of color image onto the object to be measured, and the camera captures the color distorted fringe pattern containing object information. Based on color separation technology, the two frames of phase-shifted fringes in the R channel and the B channel of the color distorted fringe pattern are separated.

[0042] As a specific embodiment of the present invention, the R color channel and the B color channel of the color image are encoded as fringes with an arbitrary phase shift amount. The expression of the single-frame color image projected by the projection light source is:

[0043]

[0044] where I(x, y) represents the light intensity distribution of a frame of color image projected by the projection light source; I r (x, y) and I b (x, y) respectively represent the phase-shifted fringes of the R and B channels of the color image; a(x, y) represents the background term in the R and B channels of the color image; b(x, y) represents the modulation degree in the R and B channels of the color image; is the phase distribution of the object to be measured; π / 2 represents the phase shift amount of the two frames of fringes in the R channel and the B channel of the color distorted fringe pattern; (x, y) is the light intensity position of the color distorted fringe pattern.

[0045] Further, a color separation method is used to separate the two frames of phase-shifted fringes in the R channel and the B channel of the color distorted fringe pattern. Due to the influence of color crosstalk, the background term, modulation degree, and phase shift amount of the two frames of phase-shifted fringe patterns after separation will change. The expression of the color distorted fringe pattern obtained by separation is:

[0046]

[0047]

[0048] where I 1 (x, y) and I 2 (x, y) respectively represent the light intensity distributions of the two frames of phase-shifted fringes separated from the color distorted image; a 1 (x, y) and a 2 (x, y) respectively represent the fringe patterns I1 (x, y) and I 2 Background intensity of (x, y); b 1 (x, y) and b 2 (x, y) are respectively the fringe pattern I 1 (x, y) and I 2 (x, y) modulation; is the phase distribution of the object to be measured; δ is the phase shift amount between two frames of phase-shifted fringes. Due to color crosstalk, a 1 (x, y) ≠ a 2 (x, y) ≠ a(x, y), b 1 (x, y) ≠ b 2 (x, y) ≠ b(x, y), δ ≠ π / 2, and the value of δ is unknown.

[0049] Furthermore, in the present invention, after separating two frames of phase-shifted fringes of the R channel and the B channel of the color-distorted fringe pattern based on the color separation technology, empirical mode decomposition is used to remove the background intensity of the two frames of phase-shifted fringe images, and two normalized frames of phase-shifted fringe patterns are obtained.

[0050] Empirical Mode Decomposition (EMD) is a method capable of processing non-linear and non-stationary one-dimensional signals. Compared with signal processing methods such as Fourier transform and wavelet transform, the EMD decomposition of signals is an adaptive data-driven process that can adaptively generate "bases" and is not restricted by the Heisenberg principle, and can achieve high precision in both time and frequency. Bidimensional Empirical Mode Decomposition (BEMD) is a method based on EMD to extend the data decomposition ability from one-dimensional data to two-dimensional data, and can adaptively analyze image signals. BEMD decomposes an image into the sum of multiple IMF components and a residual RES component through multiple iterations, and these single-frequency signals are called Bidimensional Intrinsic Mode Function (BIMF).

[0051] Respectively perform empirical mode decomposition on the separated phase-shifted fringe pattern I 1 (x, y) and I 2 (x, y). As a specific embodiment of the present invention, the specific steps of performing empirical mode decomposition on the separated phase-shifted fringe pattern I 1 (x, y) include:

[0052] (1) Initialization, let f 0 (x, y) = I 1 (x, y), i = 1;

[0053] (2) To obtain the i-th order two-dimensional intrinsic mode function, the steps are as follows:

[0054] 8) Initialize, let k = 0, H k (x, y) = f i-1 (x, y).

[0055] 9) Find all the maximum and minimum points of H k (x, y).

[0056] 10) Use the cubic spline interpolation function to interpolate the maximum and minimum points respectively to obtain the upper envelope E max (x, y) and the lower envelope E min (x, y).

[0057] 11) Take the mean of the upper and lower envelopes:

[0058]

[0059] M k (x, y) is the mean envelope.

[0060] 12) Subtract the mean envelope from the signal to obtain the residue:

[0061] H k+1 (x, y) = H k (x, y) - M k (x, y) (5)

[0062] H k+1 (x, y) is the residue after removing the mean envelope.

[0063] 13) Judge whether the obtained residue meets the BIMF condition through the standard deviation. If the standard deviation value is less than the threshold, the obtained residue can be used as a BIMF component. Let IMF i (x, y) = H k+1 (x, y), then go to step 7); otherwise, replace k with k + 1 and go to step 2) to continue the process.

[0064] 14) Obtain the i-th order residue component:

[0065] res i (x, y) = res i-1 (x, y) - IMF i (x, y) (6)

[0066] res i (x, y) is the i-th order residue component, res i-1 (x, y) is the (i - 1)-th order residue component. If the i-th order residue component resi If the number of extreme points in (x, y) is not zero, then replace i with i + 1, and set res i (x, y) as a new initial signal, and then go to step 2); otherwise, the decomposition process ends.

[0067] In this embodiment, the standard deviation in step 6) is defined as:

[0068]

[0069] where s d is the standard deviation, and n and m respectively represent the number of rows and columns of the fringe pattern. The threshold ε is generally set according to empirical values, usually 0.2 - 0.3.

[0070] In step 6), the BIMF conditions are: ① The difference between the number of extreme points and the number of zero - crossing points should not exceed 1 at most; ② In the local area, the mean value of the upper envelope formed by all maxima and the lower envelope formed by all minima is zero.

[0071] For the separated phase - shifted fringe pattern I 2 (x, y), in the initialization step of empirical mode decomposition, let f 0 (x, y) = I 2 (x, y), and the remaining steps are similar to the decomposition steps of the above - mentioned phase - shifted fringe pattern I 1 (x, y), which will not be elaborated here.

[0072] Each IMF decomposed by the above - mentioned decomposition method corresponds to signals with different frequencies in the fringe pattern, and each IMF is arranged from high - frequency to low - frequency. Under normal conditions, the background term of the fringe pattern is a slowly - varying low - frequency signal. Select and remove the IMF corresponding to the background term of the fringe pattern, and then reconstruct the remaining IMFs to obtain the distorted fringe pattern after removing the background term. Then, the expressions of the two normalized phase - shifted fringe patterns are as follows:

[0073]

[0074]

[0075] I 1 ′(x, y) and I 2 ′(x, y) are respectively the two normalized phase - shifted fringe patterns.

[0076] Furthermore, in the present invention, after obtaining the two normalized phase - shifted fringe patterns, the phase distributions of the two normalized phase - shifted fringe patterns are extracted by Schmidt orthogonalization.

[0077] For simplicity, the image intensity coordinates (x, y) are omitted in the following process.

[0078] As a specific embodiment of the present invention, the specific steps for extracting the phase distribution of two normalized phase-shifted fringe patterns by Schmidt orthogonalization include:

[0079] (1) By normalizing the fringe pattern I 1 ′, we can obtain

[0080]

[0081] where is the normalized fringe pattern, n and m respectively represent the number of rows and columns of the fringe pattern; <·> represents the inner product operator; ‖·‖ represents the two-norm.

[0082] (2) Calculate the orthogonal quantity of the fringe pattern I′ 2 relative to

[0083]

[0084]

[0085] where

[0086] If the number of fringes in the fringe pattern is greater than 1, then we can obtain:

[0087]

[0088]

[0089] According to equations (13) and (14), equation (11) can be rewritten as:

[0090]

[0091] Finally, according to the above formula, the phase distribution of the object is expressed as follows:

[0092]

[0093] Furthermore, in the present invention, after extracting the phase distribution of two normalized phase-shifted fringe patterns by Schmidt orthogonalization, the three-dimensional shape of the object is reconstructed based on the phase distribution of the two normalized phase-shifted fringe patterns.

[0094] As a specific embodiment of the present invention, the three-dimensional shape of the object can be reconstructed based on the phase-height mapping formula, and the reconstruction is specifically carried out according to the following formula:

[0095]

[0096] Among them, L represents the height from the camera to the object in the three-dimensional imaging system; d is the distance from the projection light source to the camera; f is the frequency of the fringe pattern.

[0097] In view of the limitations of single-frame measurement methods and multi-frame measurement, the present invention proposes an accurate and fast three-dimensional measurement method. By using empirical mode decomposition to remove the non-uniform background term, and using Schmidt orthogonalization to extract the phase distribution of the object, the three-dimensional shape of the object can be reconstructed with a single frame of image, solving the limitation of low accuracy in single-frame three-dimensional measurement methods. The method proposed by the present invention has the advantages of strong robustness and fast measurement, providing technical support for the development of the field of fast three-dimensional measurement.

[0098] To further understand the present invention, the following combines Figure 1 to elaborate in detail on the three-dimensional measurement method for moving objects of the present invention.

[0099] As Figure 1 shown, according to a specific embodiment of the present invention, a three-dimensional measurement method for moving objects is provided, which specifically includes the following steps.

[0100] Step 1, a projection light source projects a single frame of color image onto the object to be measured. The expression of the single frame of color image projected by the projection light source is

[0101] A camera is used to capture a color distorted fringe pattern containing object information. Based on color separation technology, the two frames of phase-shifted fringes in the R channel and B channel of the color distorted fringe pattern are separated. The expressions of the separated color distorted fringe patterns are: and

[0102] Step 2, empirical mode decomposition is used to remove the background intensity of the two frames of phase-shifted fringe images, and the two frames of phase-shifted fringe images after normalization are obtained.

[0103] Step 3, the phase distribution of the two frames of phase-shifted fringe images after normalization is extracted through Schmidt orthogonalization

[0104] Step 4, according to the three-dimensional shape of the object is reconstructed.

[0105] In summary, the present invention provides a three-dimensional measurement method for moving objects. This three-dimensional measurement method for moving objects encodes two frames of phase-shifted fringes in the R and B channels of the projection light source, uses color separation technology to separate the single frame of color distorted fringe pattern obtained by the camera, removes the uneven background intensity of the two frames of fringe patterns through empirical mode decomposition technology, and uses Schmidt orthogonalization to extract the phase information of the object. The present invention overcomes the limitation of low measurement accuracy of the Fourier single-frame method and has the advantages of strong robustness and fast measurement.

[0106] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A three-dimensional measurement method for a moving object, characterized in that, the three-dimensional measurement method for the moving object includes: A projection light source projects a frame of color image onto an object to be measured, a camera is used to capture a color distorted fringe pattern containing object information, and two frames of phase-shifted fringes in the R channel and B channel of the color distorted fringe pattern are separated based on color separation technology; Empirical mode decomposition is used to remove the background intensity of the two frames of phase-shifted fringe images, and two frames of normalized phase-shifted fringe images are obtained; The phase distribution of the two frames of normalized phase-shifted fringe images is extracted through Schmidt orthogonalization; The three-dimensional shape of the object is reconstructed according to the phase distribution of the two frames of normalized phase-shifted fringe images.

2. The three-dimensional measurement method for a moving object according to claim 1, characterized in that, The expression of the color distortion fringe pattern after color separation is and where, I 1 (x, y) and I 2 (x, y) respectively represent the light intensity distributions of two frames of phase-shifted fringes separated from the color distortion image; a 1 (x, y) and a 2 (x, y) respectively represent the background intensities of the fringe patterns I 1 (x, y) and I 2 (x, y), a 1 (x, y) ≠ a 2 (x, y); b 1 (x, y) and b 2 (x, y) are respectively the modulation degrees of the fringe patterns I 1 (x, y) and I 2 (x, y), b 1 (x, y) ≠ b 2 (x, y); is the phase distribution of the object to be measured; δ is the phase shift amount between two frames of phase-shifted fringes.

3. The three-dimensional measurement method for a moving object according to claim 2, characterized in that, For the separated phase-shifted fringe pattern I 1 (x, y) or I 2 (x, y) The specific steps of empirical mode decomposition include: (1) Initialize, let f 0 (x, y) = I 1 (x, y), i = 1, or let f 0 (x, y) = I 2 (x, y), i = 1; (2) Obtain the i-th order two-dimensional intrinsic mode function: 1) Initialize, let k = 0, H k (x, y) = f i-1 (x, y), 2) Find H k All the maximum and minimum points of (x, y), 3) Use cubic spline interpolation functions to interpolate the maximum points and minimum points respectively to obtain the upper envelope surface E max (x, y) and the lower envelope surface E min (x, y), 4) Take the mean of the upper and lower envelopes: where M k (x, y) is the mean envelope, 5) Subtract the mean envelope from the signal to obtain a residue: H k+1 (x, y) = H k (x, y) - M k (x, y) Among them, H k+1 (x, y) is the remainder after removing the mean envelope, 6) Determine whether the obtained residue meets the BIMF condition by the standard deviation. If the standard deviation value is less than the threshold, the obtained residue can be used as a BIMF component, and let IMF i (x, y) = H k+1 (x, y), and then go to step 7); otherwise, replace k with k + 1, go back to step 2) to continue the process. 7) Obtain the i-th order residual component: res i (x, y) = res i-1 (x, y) - IMF i (x, y) where res i (x, y) is the i-th order residual component, res i-1 (x, y) is the (i - 1)-th order residual component, If the number of extreme points in the \(i\)-th order residual component \(res\) i (x, y) is not zero, then let \(i + 1\) replace \(i\), and take \(res\) i (x, y) as a new initial signal, and then go to step 2); otherwise, the decomposition process ends.

4. The three-dimensional measurement method for a moving object according to claim 3, characterized in that, The standard deviation of step 6) is defined as where s d is the standard deviation, and n and m represent the number of rows and columns of the fringe pattern, respectively.

5. The three-dimensional measurement method for a moving object according to claim 3 or 4, characterized in that, the BIMF conditions are: (1) The difference between the number of extreme points and the number of zero crossings should not exceed 1 at most; (2) In the local area, for the upper envelope formed by all maxima and the lower envelope formed by all minima, their mean value is zero.

6. The three-dimensional measurement method for a moving object according to claim 1, characterized in that, Phase distribution where I′ 1 and I′ 2 are two normalized phase-shifted fringe patterns respectively, <·> represents the inner product operator; ||·|| represents the two-norm.

7. The three-dimensional measurement method for a moving object according to any one of claims 1 to 6, characterized in that, According to reconstruct the three-dimensional shape of an object, where h(x, y) is the three-dimensional shape data of the object, L represents the height from the camera to the object in the three-dimensional imaging system; d is the distance from the projection light source to the camera; and f is the frequency of the fringe pattern.

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