A four-color channel dynamic three-dimensional measurement device and method

Abstract

The application discloses a four-color channel dynamic three-dimensional measurement device and method, and belongs to the field of projection three-dimensional measurement. The four-color channel dynamic three-dimensional measurement device comprises a PPC array color image coding camera, an imaging objective lens and a four-color composite phase shift stripe structure light projector. The PPC array color image coding camera comprises an incident end optical fiber array, a waveguide optical fiber bundle and a PPC array. The PPC array color image coding camera collects a composite phase shift stripe coding image through one-time exposure. The composite phase shift stripe coding image is decoded into four different color modulation stripe images with a phase difference of π / 2. Then, three-dimensional coordinates of a dynamic measured target surface are obtained through phase demodulation and coordinate conversion, four-color channel dynamic three-dimensional measurement is realized, and the application is suitable for occasions with high requirements for visual measurement speed and precision.

Description

Technical Field

[0001] This invention relates to a four-color-channel dynamic three-dimensional measurement device and method, belonging to the field of projection three-dimensional measurement. Background Technology

[0002] Currently, dynamic 3D measurement of color channels mainly utilizes existing RGB cameras and digital projectors for three-step phase-shift profile measurement. However, due to the asymmetry of the mathematical model and the large phase difference in this method, the image phase is susceptible to noise interference, leading to reduced measurement accuracy. The four-step phase-shift profile measurement method is generally recognized in the field as having a symmetrical mathematical model and good robustness. However, it is limited by the fact that conventional color cameras only have three channels with overlapping spectra, preventing the realization of dynamic 3D measurement. Summary of the Invention

[0003] In view of the above-mentioned prior art, the present invention provides a four-color channel dynamic three-dimensional measurement device and method to solve the above-mentioned problems.

[0004] The technical solution of this invention, a four-color-channel dynamic three-dimensional measurement device, is as follows: the device includes a PPC array color image encoding camera, an imaging objective lens, and a four-color composite phase-shifting fringe structured light projector; the four-color composite phase-shifting fringe structured light projector projects four non-overlapping color composite phase-shifting fringe structured light bands with a phase difference of π / 2 at the same time; after being modulated by the depth information of the dynamically measured target, the imaging objective lens images the bending and changing composite phase-shifting fringe pattern onto the PPC array color image encoding camera; the PPC array color image encoding camera acquires the composite phase-shifting fringe encoded image in a single exposure, and decodes the composite phase-shifting fringe encoded pattern into four modulated fringe images with a phase difference of π / 2 in different colors, and then obtains the three-dimensional coordinates of the surface of the dynamically measured target through phase demodulation and coordinate conversion, thereby realizing four-color-channel dynamic three-dimensional measurement.

[0005] The PPC array color image encoding camera includes an incident fiber array, a waveguide fiber bundle, and a PPC array. The incident fiber array consists of m×n fiber bundle incident ends, serving as an imaging receiving surface to receive imaging light and guide it into the waveguide fiber bundle. The waveguide fiber bundle allows the imaging light to be transmitted through total internal reflection to each PPC. The PPC array consists of m×n PPCs, which separate the imaging light into different wavelength bands and output them at corresponding photonic crystal apertures. The PPCs have regularly distributed crystal apertures with a spacing on the order of micrometers. The introduced imaging light is separated into different wavelength bands under crystal resonance and emitted sequentially from the photonic crystal apertures, with the emission wavelength determined by the resonant wavelength of the photonic crystal aperture. The four light bands projected by the four-color composite phase-shifting fringe structured light projector are the same as the four light bands separated by the crystal apertures on the PPC array color image encoding camera, achieving spectral matching.

[0006] The present invention proposes a four-color-channel dynamic three-dimensional measurement method, which utilizes the aforementioned four-color-channel dynamic three-dimensional measurement device and follows these steps:

[0007] Step 1: The four-color composite phase-shifting fringe structured light projector projects four non-overlapping color composite phase-shifting fringe structured light bands with a phase difference of π / 2 at the same time. After being modulated by the depth information of the target under test, the imaging objective lens images the curved composite phase-shifting fringe pattern onto the PPC array color image encoding camera. The PPC array color image encoding camera acquires a composite phase-shifting fringe encoded image I0(u,v) in a single exposure, where 0 < u ≤ 4n, 0 < v ≤ m, and 4n and m are the number of pixels on the x and y axes of the encoded image, respectively. In the encoded image I0(u,v), every four pixels in the x-direction form a group, representing the light intensity grayscale values ​​of four different light bands of the same target point.

[0008] Step 2: Multiply the encoded image I0(u,v) by the decoding matrices M1, M2, M3, and M4 respectively to obtain four modulated stripe images I with different colors and π / 2 phase differences. λ1 (x,y), I λ2 (x,y), I λ3 (x,y) and I λ4 (x,y).

[0009]

[0010] in,

[0011]

[0012]

[0013]

[0014] Step 3: Define the expression I for the modulation stripe image of four different colors with a π / 2 phase difference. λ1 (x,y), I λ2 (x,y), I λ3 (x,y) and I λ4 (x,y) is:

[0015]

[0016] a1(x,y), a2(x,y), a3(x,y), and a4(x,y) are the grayscale values ​​of the background light intensity in the four light bands; b1(x,y), b2(x,y), b3(x,y), and b4(x,y) are the amplitude values ​​of the projected light intensity of the four-color composite phase-shifting stripe structured light projector in the four light bands.

[0017] By controlling b1(x,y), b2(x,y), b3(x,y), and b4(x,y) of the four-color composite phase-shifting stripe structured light projector, the modulation stripe image is normalized; let the normalization constant be k, where k ranges from (0,1), and the normalization condition be:

[0018]

[0019] Step 4: Phase Demodulation

[0020]

[0021] Step 5: World coordinate calculation; depth information, i.e., world coordinate system z. w The phase-depth mapping function relationship can be obtained; world coordinate system x w and y w It can be calculated using the Gaussian imaging formula; thus, dynamic three-dimensional measurement of the target is finally achieved.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The present invention provides a four-color-channel dynamic three-dimensional measurement device and method, which uses a PPC array color image encoding camera to achieve three-dimensional measurement of dynamic targets across four channels. The four-color-channel dynamic three-dimensional measurement device completes multi-band spectral imaging in a single exposure, meaning it can simultaneously acquire four phase-shifted images at any given time, enabling three-dimensional measurement of dynamic targets. Compared with existing technologies, the four-color-channel dynamic three-dimensional measurement method provided by the present invention achieves four-step phase-shift calculation, improving measurement accuracy and making it suitable for applications requiring high speed and accuracy in visual measurements. Attached Figure Description

[0024] Figure 1The structural diagram of the four-color channel dynamic three-dimensional measurement device provided by the present invention;

[0025] Figure 2 This is a schematic diagram of the decoding of the composite phase-shifting stripe encoding pattern of the present invention.

[0026] In the figure: 1-Incident fiber array, 2-Waveguide fiber bundle, 3-PPC array, 10-PPC array color image encoding camera, 20-Imaging objective, 30-Dynamic target under test, 40-Four-color composite phase-shifting stripe structured light projector. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to specific embodiments.

[0028] like Figure 1 As shown, the present invention discloses a four-color-channel dynamic three-dimensional measurement device, comprising a PPC array color image encoding camera 10, an imaging objective lens 20, and a four-color composite phase-shifting fringe structured light projector 40. The four-color composite phase-shifting fringe structured light projector 40 projects four non-overlapping color composite phase-shifting fringe structured light bands with a phase difference of π / 2 at the same time. After being modulated by the depth information of the dynamically measured target 30, the imaging objective lens 20 images the curved composite phase-shifting fringe pattern onto the PPC array color image encoding camera 10. The PPC array color image encoding camera 10 acquires the composite phase-shifting fringe encoded image in a single exposure. By decoding the composite phase-shifting fringe encoded pattern into four modulated fringe images with a phase difference of π / 2 in different colors, the three-dimensional coordinates of the surface of the dynamically measured target 30 are obtained through phase demodulation and coordinate conversion, thereby realizing four-color-channel dynamic three-dimensional measurement.

[0029] This invention is one.

[0030] The PPC array color image encoding camera 10 includes an incident fiber array 1, a waveguide fiber bundle 2, and a PPC array 3. The incident fiber array 1 consists of m×n fiber bundles at the incident end, serving as an imaging receiving surface to receive imaging light and guide it into the waveguide fiber bundle 2. The waveguide fiber bundle 2 allows the imaging light to be transmitted to each PPC through total internal reflection. The PPC array 3 consists of m×n PPCs, which separate the imaging light into different wavelength bands and output them at corresponding photonic crystal apertures. The PPCs have regularly distributed crystal apertures with a spacing on the order of micrometers. The introduced imaging light is separated into different wavelength bands under crystal resonance and emitted sequentially from the photonic crystal apertures. The emission wavelength is determined by the resonant wavelength of the photonic crystal aperture. The four light bands projected by the four-color composite phase-shifting fringe structured light projector are the same as the four light bands separated by the crystal apertures on the PPC array color image encoding camera, achieving spectral matching.

[0031] The present invention proposes a four-color-channel dynamic three-dimensional measurement method, which utilizes the aforementioned four-color-channel dynamic three-dimensional measurement device and follows these steps:

[0032] Step 1: The four-color composite phase-shifting fringe structured light projector 40 projects four non-overlapping color composite phase-shifting fringe structured light bands with a phase difference of π / 2 at the same time. After being modulated by the depth information of the dynamically measured target 30, the imaging objective lens 20 images the curved composite phase-shifting fringe pattern onto the PPC array color image encoding camera 10. The PPC array color image encoding camera 10 acquires a composite phase-shifting fringe encoded image I0(u,v) in a single exposure, where 0 < u ≤ 4n, 0 < v ≤ m, and 4n and m are the number of pixels on the x and y axes of the encoded image, respectively. In the encoded image I0(u,v), every four pixels in the x-direction form a group, representing the light intensity grayscale values ​​of four different light bands of the same measured point.

[0033] Step 2: Multiply the encoded image I0(u,v) by the decoding matrices M1, M2, M3, and M4 respectively to obtain four modulated stripe images I with different colors and π / 2 phase differences. λ1 (x,y), I λ2 (x,y), I λ3 (x,y) and I λ4 (x,y).

[0034]

[0035] in,

[0036]

[0037]

[0038]

[0039] Step 3: Define the expression I for the modulation stripe image of four different colors with a π / 2 phase difference. λ1 (x,y), I λ2 (x,y), I λ3 (x,y) and I λ4 (x,y) is:

[0040]

[0041] a1(x,y), a2(x,y), a3(x,y), and a4(x,y) are the grayscale values ​​of the background light intensity in the four light bands; b1(x,y), b2(x,y), b3(x,y), and b4(x,y) are the amplitude values ​​of the projected light intensity of the four-color composite phase-shifting stripe structured light projector 40 in the four light bands.

[0042] By controlling b1(x,y), b2(x,y), b3(x,y), and b4(x,y) of the four-color composite phase-shifting stripe structured light projector 40, the modulation stripe image is normalized; let the normalization constant be k, where k ranges from (0,1), and the normalization condition be:

[0043]

[0044] Step 4: Phase Demodulation

[0045]

[0046] Step 5: World coordinate calculation; depth information, i.e., world coordinate system z. w The phase-depth mapping function relationship can be obtained; world coordinate system x w and y w It can be calculated using the Gaussian imaging formula; it can be seen that through steps one, two, three, four, and five, dynamic three-dimensional measurement of the target can be achieved.

[0047] Example:

[0048] The invention will be further described in detail below with an example:

[0049] A 720×1280 PPC array is selected. The incident fiber array 1 consists of 720×1280 fiber bundles as the incident end, which serves as the imaging receiving surface to receive the imaging light and guide the imaging light into the waveguide fiber bundle 2. Four crystal holes are photolithographically etched on each PPC, and the structural size of each crystal hole is controlled. Different structural sizes result in different output light bands, namely λ1=(450nm,480nm), λ2=(510nm,540nm), λ3=(580nm,595nm), and λ4=(610nm,640nm).

[0050] The four-color composite phase-shifting stripe structured light projector projects structured light in four wavelength bands: λ1 = (450nm, 480nm), λ2 = (510nm, 540nm), λ3 = (580nm, 595nm), and λ4 = (610nm, 640nm).

[0051] The PPC array color image encoding camera 10 acquires a composite phase-shifted stripe encoded image I0(u,v) in a single exposure, which is a 720×5120 matrix; the decoding matrices M1, M2, M3, and M4 are all 5120×1280 matrices; wherein the element in the p-th column and (p-1)×4+1-th row of M1 is 1, and all other elements are 0; the element in the p-th column and (p-1)×4+2-th row of M2 is 1, and all other elements are 0; the element in the p-th column and (p-1)×4+3-th row of M3 is 1, and all other elements are 0; the element in the p-th column and (p-1)×4+4-th row of M4 is 1, and all other elements are 0; p = 1, 2, 3, ... 1280; the decoded modulated stripe image I0(u,v) is a 720×5120 matrix; the decoding matrices M1, M2, M3, and M4 are all 5120×1280 matrices ... λ1 (x,y), I λ2 (x,y), I λ3 (x,y) and I λ4 (x,y) are both 720×1280 matrices; the normalization constant k can be 0.5.

[0052] The world coordinates (x, y, y) of the surface points of the dynamically measured target are obtained by using the phase calculation formula (4) and world coordinate calculation. w ,y w ,z w The example implements dynamic three-dimensional measurement with four color channels.

[0053] In this invention, the world coordinate system z is calculated using the phase-depth mapping function relationship. w The imaging formula calculates the world coordinate system x. w and y w The method is common knowledge in the field and will not be described in detail here. The range of the number of pixels in each main band and the normalization constant of the PPC array color image encoding camera can be set to k according to requirements, and it is not limited to this embodiment.

[0054] Although the present invention has been described above with reference to the figures, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.

Claims

1. A four-color channel dynamic three-dimensional measuring device, characterized by, The four-color channel dynamic three-dimensional measurement device comprises a PPC array color image encoding camera (10), an imaging objective (20), and a four-color composite phase shift fringe structured light projector (40); the four-color composite phase shift fringe structured light projector (40) projects four light wave bands of π / 2 phase difference color composite phase shift fringe structured light which do not overlap with each other at the same time; After being modulated by depth information of a dynamic measured target (30), the imaging objective (20) images the curved and changed composite phase shift fringe pattern to the PPC array color image encoding camera (10); the PPC array color image encoding camera (10) collects a composite phase shift fringe encoding image through one-time exposure, decodes the composite phase shift fringe encoding pattern into four π / 2 phase difference modulation fringe images of different colors, and then obtains three-dimensional coordinates of the surface of the dynamic measured target (30) through phase demodulation and coordinate conversion, so that four-color channel dynamic three-dimensional measurement is realized; The PPC array color image encoding camera (10) comprises an incident end optical fiber array (1), a waveguide optical fiber bundle (2), and a PPC array (3); the incident end optical fiber array (1) is composed of m×n optical fiber bundle incident ends, serves as an imaging receiving surface, receives imaging light, and guides the imaging light into the waveguide optical fiber bundle (2); the waveguide optical fiber bundle (2) makes the imaging light be totally reflected and transmitted to each PPC; the PPC array (3) is composed of m×n PPCs, separates the imaging light into different wavelength light, and outputs the different wavelength light from corresponding photonic crystal holes; the PPCs are regularly distributed with crystal holes, the hole distance is in the order of microns, the imaging light is guided into the PPCs, and the imaging light is separated into different wavelength light under crystal resonance and is sequentially output from the photonic crystal holes, and the output wavelength is determined by the resonance wavelength of the photonic crystal hole.

2. A four-color channel dynamic three-dimensional measurement method, characterized by, The four-color channel dynamic three-dimensional measurement device is used for color image encoding, and the following steps are included: Step one, the four-color composite phase shift fringe structured light projector (40) projects four light wave bands of π / 2 phase difference color composite phase shift fringe structured light which do not overlap with each other at the same time; after being modulated by depth information of a dynamic measured target (30), the imaging objective (20) images the curved and changed composite phase shift fringe pattern to the PPC array color image encoding camera (10); the PPC array color image encoding camera (10) collects a composite phase shift fringe encoding image I0(u,v), 0 Step two, multiply the coded image I0(u,v) with the decoding matrix M1, M2, M3 and M4 respectively, to get four images of π / 2 phase difference modulated fringe pattern I λ1 (x,y), I λ2 (x,y), I λ3 (x,y) and I λ4 (x,y); wherein Step three, define the four different color pi / 2 phase difference modulation fringe image expressions I λ1 (x,y), I λ2 (x,y), I λ3 (x,y), and I λ4 (x,y) are: a1(x,y), a2(x,y), a3(x,y) and a4(x,y) are the light intensity gray scale values of background light in four light wave bands; b1(x,y), b2(x,y), b3(x,y) and b4(x,y) are the projection light intensity amplitude values of the four-color composite phase shift fringe structured light projector (40) in four light wave bands; By controlling the b1(x,y), b2(x,y), b3(x,y) and b4(x,y) of the four-color complex phase-shift fringe structure light projector (40), the modulation fringe image normalization is realized; the normalization constant is k, the range of k is (0, 1), and the normalization condition is: Step four, phase demodulation: Step five, world coordinate calculation; depth information, world coordinate system z w Through the phase depth mapping function relationship can be obtained; world coordinate system x w And y w Can be calculated by Gaussian imaging formula; it can be seen that through steps one, two, three, four, five, dynamic target three-dimensional measurement can be achieved.

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