A multi-spectral based structured light measurement system and method

Abstract

The present application relates to a kind of multispectral-based structured light measurement system and method, including projection system, imaging system, control and operation board card and PC machine, control and operation board card are connected with projection system and imaging system control respectively, and control and operation board card are connected with PC machine control, projection system is used to project the structured light image with coding.The present application utilizes structured light projection device to project to the measured object, by the wavelength modulation of illumination light, can project multiple different waveband structured light image respectively, then fuse these different waveband coding structured light to decode calculation when decoding calculation, can improve the adaptability of 3D structured light detection, reduce the influence of the color, material and surface roughness of the measured object on 3D detection precision, reduce noise and interference.

Description

Technical Field

[0001] This invention relates to the field of optical detection technology, and in particular to a multispectral structured light measurement system and method. Background Technology

[0002] The continuous advancement of science and technology has led to increasingly higher demands for information about objects, shifting from two-dimensional to three-dimensional measurement. Rapidly and accurately acquiring three-dimensional information about objects has become a key issue in fields such as rapid product design, product quality inspection, medical testing, cultural relic preservation, automatic navigation, and virtual reality. The rapid development of optical measurement technology and computer technology has enabled traditional contact coordinate measuring machines (CMMs) to gradually transform into non-contact optical 3D measurement systems.

[0003] Non-contact optical 3D measurement not only avoids contact with the object being measured, but also facilitates automation, and has broad application prospects in various fields. Moreover, it has high accuracy, meeting people's usage needs. Among non-contact 3D measurement methods, active structured light measurement has developed the most rapidly. It involves projecting coded structured light onto the object being measured through a projection device, and capturing images of the structured light that are modulated and deformed by the object being measured through a camera at a certain angle to the projection device. Then, the 3D point cloud of the object being measured is obtained by image processing and calculation on the image carrying the three-dimensional morphology information of the surface of the object being measured.

[0004] Based on the different encoding and decoding calculation methods, there are three main types of active 3D structured light detection methods: the first is the Fourier transform decoding method based on static image processing, the second is the single-frequency phase shift plus Gray code method, and the third is the multi-frequency phase shift method.

[0005] In all current active 3D structured light detection methods, regardless of the encoding calculation method used, the illumination source of the projected structured light is a single wavelength, with blue light being the most commonly used.

[0006] However, in actual testing, we found that due to the color, material, and surface roughness of the object being tested, using only blue light or other single light sources can result in insufficient contrast in the acquired object surface image, which in turn affects the generation of point clouds and reduces measurement accuracy.

[0007] In view of the above-mentioned shortcomings, the designer has actively researched and innovated in order to create a multispectral structured light measurement system and method, which will have greater industrial application value. Summary of the Invention

[0008] To address the aforementioned technical problems, the present invention aims to provide a multispectral structured light measurement system and method. When projecting structured light onto the object under test using a structured light projection device, multiple structured light images of different wavelengths can be projected by modulating the wavelength of the illumination light. Then, during decoding calculation, these coded structured light images of different wavelengths are fused together for decoding calculation, which can improve the adaptability of 3D structured light detection and reduce the impact of the color, material, and surface roughness of the object under test on the accuracy of 3D detection.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] One of the objectives of this invention is:

[0011] A multispectral structured light measurement system includes a projection system, an imaging system, a control and computing board, and a PC. The control and computing board is connected to both the projection system and the imaging system, and is also connected to the PC. The projection system projects an coded structured light image. The imaging system acquires the structured light image modulated by the object under test, facilitating subsequent image processing by the control and computing board. The control and computing board controls the projection system to project the coded structured light image, processes the image acquired by the imaging system to obtain a 3D point cloud of the object under test, and transmits the final 3D point cloud calculation result to the PC. The PC displays and performs post-processing operations on the 3D point cloud data.

[0012] As a further improvement of the present invention, the projection system projects multiple coded structured lights, and the imaging system performs image acquisition synchronously with the projection system.

[0013] As a further improvement of the present invention, the illumination source of the projection system is multi-band or broadband.

[0014] The second objective of this invention is:

[0015] A multispectral structured light measurement method includes the following steps:

[0016] Step S1: The control and computing board controls the projection system to project wavelength λ. i Encoded structured light;

[0017] Step S2: The projection system projects wavelength λ. i Encoded structured light is projected onto the surface of the object under test;

[0018] Step S3: The imaging system captures an image modulated by the object under test;

[0019] Step S4: The control and processing board performs a Fourier transform on the acquired image to obtain the value of the object under test in λ. i 3D point cloud data in the band;

[0020] Step S5: For each pixel of the object under test, fuse its different wavelength bands of λ. i 3D point cloud maps to improve the quality of 3D point clouds;

[0021] Step S6: The control and computing board transmits the fused 3D point cloud data to the PC for display and post-processing.

[0022] As a further improvement of the present invention, the control and computing board calculates the 3D point cloud data (x, y) of each pixel position (x, y) of the object under test based on the pixel position (x, y) of the object under different wavelengths. i y i , z i The 3D point cloud is fused point by point to obtain the final 3D point cloud image.

[0023] As a further improvement of the present invention, the structured light is structured light based on Fourier transform of a single image or structured light based on single-frequency phase shift and Gray code, specifically including the following steps:

[0024] Step S1: The control and computing board controls the projection system to project coded structured light of wavelength λ1. Then, the imaging system acquires the projected image illuminating the object under test and transmits the acquired image to the control and computing board for decoding and calculation to obtain the 3D point cloud data of the object under test in the λ1 band.

[0025] Step S2: The control and computing board controls the projection system to project the same coded structured light at wavelength λ2. Then, the imaging system acquires the projected image illuminating the object under test and transmits the acquired image to the control and computing board for decoding and calculation to obtain the 3D point cloud data of the object under test at wavelength λ2.

[0026] Step S3: Repeat the above process continuously until the control and calculation board controls the projection system to project λ. N The same coded structured light is projected at the same wavelength, and then the imaging system acquires the projected image illuminating the object under test and transmits the acquired image to the control and computing board for decoding and calculation to obtain the λ value in that wavelength band. N 3D point cloud data of the object under test;

[0027] Step S4: Combine the analysis of the analyte in different wavelength bands (λ1, λ2...λ) N In the 3D point cloud image below, assuming that for a certain pixel, the point cloud value in band λ1 is (x1, y1, z1), and the point cloud value in band λ2 is (x2, y2, z3), λ N The band point cloud value is (x N ,y N ,z NIf the final point cloud value at that pixel is ((x1+x2+……+x), then the final point cloud value at that pixel is ((x1+x2+……+x)). N ) / N, (y1+y2+……+y N ) / N, (z1+z2+……+z N If the point cloud value of a certain band is invalid, then its point cloud value is removed and not included in the calculation.

[0028] As a further improvement of the present invention, the structured light is a multi-frequency phase-shift based structured light, specifically including the following steps:

[0029] Step S1: First, the coded structured light at the first frequency f1 is illuminated using the λ1 band; the coded structured light at the second frequency f2 is illuminated using the λ2 band; and so on, until the Nth frequency f N The coded structured light uses λ N Band illumination;

[0030] Step S2: Repeat the above process continuously until the control and computing board controls the projection system to project λ. N The same coded structured light is projected at the same wavelength, and then the imaging system acquires the projected image illuminating the object under test and transmits the acquired image to the control and computing board for decoding and calculation to obtain the λ value in that wavelength band. N 3D point cloud data of the object under test;

[0031] Step S3: Combine the analysis of the analyte in different wavelength bands (λ1, λ2...λ) N In the 3D point cloud image below, assuming that for a certain pixel, the point cloud value in band λ1 is (x1, y1, z1), and the point cloud value in band λ2 is (x2, y2, z3), λ N The band point cloud value is (x N ,y N ,z N If the final point cloud value at that pixel is ((x1+x2+……+x), then the final point cloud value at that pixel is ((x1+x2+……+x)). N ) / N, (y1+y2+……+y N ) / N, (z1+z2+……+z N If the point cloud value of a certain band is invalid, then its point cloud value is removed and not included in the calculation.

[0032] By means of the above-described solution, the present invention has at least the following advantages:

[0033] This invention integrates coded structured light across multiple bands during detection, which can improve the contrast of the reflected image from the object's surface and thus enhance detection accuracy.

[0034] When the structured light projection device projects onto the object under test, the present invention can project multiple structured light images of different wavelengths by modulating the wavelength of the illumination light. Then, during the decoding calculation, the encoded structured light of these different wavelengths is fused together for decoding calculation, which can improve the adaptability of 3D structured light detection, reduce the impact of the color, material and surface roughness of the object under test on the accuracy of 3D detection, and reduce noise and interference.

[0035] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram illustrating the structural principle of a multispectral structured light measurement system and method according to the present invention.

[0038] Figure 2 This is a flowchart of the detection method of the present invention;

[0039] Figure 3 This is a schematic diagram of the gold fingers on an FPC line under 650nm light source illumination;

[0040] Figure 4 This is a schematic diagram of the gold fingers on an FPC line under 600nm light source illumination;

[0041] Figure 5 This is a schematic diagram of the gold fingers on an FPC line under 550nm light source illumination;

[0042] Figure 6 This is a schematic diagram of the gold fingers on an FPC line under 500nm light source illumination;

[0043] Figure 7 This is a schematic diagram of the gold fingers on an FPC line under 450nm light source illumination.

[0044] The meanings of the labels in the figures are as follows.

[0045] 1. Projection system 2. Imaging system

[0046] 3 Control and computing boards 4 PC

[0047] 5 Test Items Detailed Implementation

[0048] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0049] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0050] Example

[0051] like Figures 1 to 7 As shown,

[0052] One of the objectives of this invention is:

[0053] Specifically, such as Figure 1 As shown,

[0054] A multispectral structured light measurement system includes a projection system 1, an imaging system 2, a control and computing board 3, and a PC 4. The control and computing board 3 is connected to the projection system 1 and the imaging system 2 respectively, and is also connected to the PC 4. The projection system 1 is used to project coded structured light images.

[0055] The imaging system 2 is used to acquire the structured light image modulated by the test object 5, so as to facilitate subsequent image processing by the control and computing board 3;

[0056] The control and computing board 3 controls the projection system 1 to project coded structured light images, processes the images acquired by the imaging system 2 to obtain the 3D point cloud of the object under test 5, and transmits the final 3D point cloud calculation results to the PC 4.

[0057] PC 4 is used to display and post-process 3D point cloud data.

[0058] Preferably, the projection system 1 projects multiple coded structured lights, and the imaging system 2 performs image acquisition synchronously with the projection system 1.

[0059] Preferably, the illumination source of the projection system 1 is multi-band or broadband.

[0060] The second objective of this invention is:

[0061] Specifically, such as Figure 2 As shown,

[0062] A multispectral structured light measurement method includes the following steps:

[0063] Step S1: Control and calculation board 3 controls the projection system 1 to project wavelength λ. i Encoded structured light;

[0064] Step S2: Projection system 1 projects wavelength λ i The coded structured light is projected onto the surface of the object under test;

[0065] Step S3: Imaging system 2 captures an image modulated by the test object 5;

[0066] Step S4: The control and calculation board 3 performs a Fourier transform on the acquired image to obtain the value of the test object 5 in λ. i 3D point cloud data in the band;

[0067] Step S5: For each pixel of the object under test 5, fuse its different wavelength bands of λ. i 3D point cloud maps to improve the quality of 3D point clouds;

[0068] Step S6: The control and computing board 3 transmits the fused 3D point cloud data to the PC 4 for display and post-processing.

[0069] Preferably, the control and computing board 3 calculates the 3D point cloud data (x, y) of each pixel position (x, y) of the object under test 5 based on different wavelengths. i y i , z i The 3D point cloud is fused point by point to obtain the final 3D point cloud image.

[0070] Preferably, the structured light is structured light based on the Fourier transform of a single image or structured light based on single-frequency phase shift and Gray code, specifically including the following steps:

[0071] Step S1: The control and computing board 3 controls the projection system 1 to project coded structured light of wavelength λ1. Then, the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the 3D point cloud data of the object under test 5 in the wavelength band λ1.

[0072] Step S2: The control and computing board 3 controls the projection system 1 to project the same coded structured light at wavelength λ2. Then, the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the 3D point cloud data of the object under test 5 at wavelength λ2.

[0073] Step S3: Repeat the above process continuously until the control and calculation board 3 controls the projection system 1 to project λ. N The same coded structured light is projected at the same wavelength, and then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the λ in this wavelength band. N 3D point cloud data of the object under test 5;

[0074] Step S4: Combine the test sample 5 in different wavelength bands (λ1, λ2...λ) N In the 3D point cloud image below, assuming that for a certain pixel, the point cloud value in band λ1 is (x1, y1, z1), and the point cloud value in band λ2 is (x2, y2, z3), λ N The band point cloud value is (x N ,y N ,z N If the final point cloud value at that pixel is ((x1+x2+……+x), then the final point cloud value at that pixel is ((x1+x2+……+x)). N ) / N, (y1+y2+……+y N ) / N, (z1+z2+……+z N If the point cloud value of a certain band is invalid, then its point cloud value is removed and not included in the calculation.

[0075] Preferably, the structured light is multi-frequency phase-shift based structured light, specifically including the following steps:

[0076] Step S1: First, the coded structured light at the first frequency f1 is illuminated using the λ1 band; the coded structured light at the second frequency f2 is illuminated using the λ2 band; and so on, until the Nth frequency f N The coded structured light uses λ N Band illumination;

[0077] Step S2: Repeat the above process continuously until the control and calculation board 3 controls the projection system 1 to project λ. N The same coded structured light is projected at the same wavelength, and then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the λ in this wavelength band. N 3D point cloud data of the object under test 5;

[0078] Step S3: Combine the test sample 5 in different wavelength bands λ1, λ2...λ NThe following is a 3D point cloud image. Assuming the point cloud at a specific pixel has point cloud values ​​of x1, y1, z1 for band λ1 and x2, y2, z3 for band λ2, ... N The band point cloud value is x N ,y N ,z N Then the final point cloud value at that pixel is x1 + x2 + ... + x N / N, y1+y2+……+y N / N, z1+z2+……+z N / N, when the point cloud value of a certain band is invalid, its point cloud is removed and not included in the calculation.

[0079] This invention proposes a multispectral structured light measurement system and method. When projecting structured light onto the object under test using a structured light projection device, multiple structured light images of different wavelengths can be projected by modulating the wavelength of the illumination light. Then, during decoding calculation, these coded structured light images of different wavelengths are fused together for decoding calculation, which can improve the adaptability of 3D structured light detection and reduce the influence of the color, material and surface roughness of the object under test on the accuracy of 3D detection.

[0080] As Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 The images shown are of the gold fingers at the FPC connector under different wavelengths of light. Due to the color of the gold fingers and the absorption of the material, they appear different in certain commonly used wavelengths (such as...). Figure 7 The image contrast is very poor under blue light (450nm).

[0081] in,

[0082] Figure 3 This is a schematic diagram of the gold fingers on an FPC line under 650nm light source illumination.

[0083] Figure 4 This is a schematic diagram of the gold fingers on an FPC line under 600nm light source illumination.

[0084] Figure 5 This is a schematic diagram of the gold fingers on an FPC line under 550nm light source illumination.

[0085] Figure 6 This is a schematic diagram of the gold fingers on an FPC line under 500nm light source illumination.

[0086] Figure 7 This is a schematic diagram of the gold fingers on an FPC line under 450nm light source illumination.

[0087] If only 3D structured light in the blue light band is used for detection, it will inevitably lead to the appearance of many invalid point clouds, thereby reducing the detection accuracy.

[0088] However, it is also present in other bands (such as...) Figure 4 Under orange-yellow light (600nm), the image contrast is significantly improved, thus the accuracy of the calculated 3D point cloud is also higher.

[0089] Therefore, the 3D detection method based on multispectral structured light can reduce the influence of the color, material and surface roughness of the test object on the generation of 3D point clouds, and improve the detection adaptability and accuracy.

[0090] Among them, projection system 1: its function is to project structured light images with specific encoding. The type and number of the encoded images are related to the encoding and decoding algorithms used. The content and number of images projected by projection system 1 are controlled by control and computing board 3.

[0091] It should be noted that the illumination source of the projection system 1 corresponding to this invention should be multi-band or broadband, and wavelength modulation can be performed according to actual needs.

[0092] Imaging system 2: Its function is to acquire the structured light image modulated by the object under test, so as to facilitate subsequent image processing by the control and computing board 3.

[0093] It is important to note that if projection system 1 projects multiple coded structured lights, then the image acquisition by imaging system 2 must be synchronized with that of projection system 1 to ensure the correctness of the coded structured light sequence and to avoid introducing miscoded or invalid point cloud data.

[0094] Furthermore, since this invention is based on multispectral detection, the devices (lens and CMOS camera) used in this imaging system must conform to the response of the corresponding band or have a wide spectral response.

[0095] Control and computing board 3: On the one hand, it controls the projection system 1 to project a specific coded structured light image; on the other hand, it processes the image acquired by the imaging system 2 to obtain the 3D point cloud of the object under test; and on the other hand, it transmits the final 3D point cloud calculation result to the PC 4.

[0096] PC 4: Its function is to display 3D point cloud data, and it can also perform corresponding post-processing according to user needs.

[0097] Specific testing methods are as follows: Figure 2 The flowchart is shown below:

[0098] After the 3D structured light detection begins, the control and computing board 3 controls the projection system 1 to first project coded structured light with a wavelength of λ1. At the same time, the imaging system 2 synchronously acquires the projected image illuminating the object under test 5. Then, the control and computing board 3 calculates the acquired projected image according to the specific coding calculation method to obtain the 3D point cloud (λ1) of the object under test.

[0099] Next, the control and computing board 3 controls the projection system 1 to continue projecting coded structured light with a wavelength of λ2, and then performs the same process as before to obtain the 3D point cloud data of the object under test 5 in the λ2 band.

[0100] Then, the same operation was performed again to obtain the value of test sample 5 at λ. N 3D point cloud data in the band.

[0101] Then, the control and computing board 3 calculates the position (x, y) of each pixel of the test object 5 based on the 3D point cloud data (x, y) calculated in different bands. i y i , z i The 3D point cloud is fused point by point to obtain a final accurate 3D point cloud image with less noise.

[0102] Where λ1, λ2……λ N The choice of N and the value of N depend on the color, material and surface morphology of the object to be measured, and their choice will ultimately affect the accuracy of the final 3D point cloud.

[0103] like Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 These are images captured by an imaging system from the gold fingers at the FPC line interface under different wavelengths of light.

[0104] Based on the different encoding and decoding calculation methods of 3D structured light, there are currently three main 3D structured light detection methods: one is structured light based on Fourier transform of a single image, another is structured light based on single-frequency phase shift and Gray code, and the third is structured light based on multi-frequency phase shift.

[0105] Below, we will describe the specific implementation of the present invention in the structured light measurement method for each of the three structured light detection methods described above.

[0106] Of course, regardless of the structured light detection method used, the first step is to select a suitable light source wavelength band λ1, λ2, ... λ based on the specific color, material, surface roughness of the item to be tested, and the required detection accuracy. N And the number of bands N. The subsequent process will vary depending on the specific detection method, and the specific implementation is as follows:

[0107] Embodiment 1 of the present invention:

[0108] 1. Structured light based on Fourier transform of a single image

[0109] The control and computing board 3 controls the projection system 1 to project an coded structured light of wavelength λ1. Then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the 3D point cloud data of the object under test 5 in the wavelength band λ1.

[0110] The control and computing board 3 controls the projection system 1 to project the same coded structured light at wavelength λ2. Then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the 3D point cloud data of the object under test at wavelength λ2.

[0111] Repeat the above process continuously until the control and calculation board 3 controls the projection system 1. N The same coded structured light is projected at the same wavelength, and then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the λ in this wavelength band. N 3D point cloud data of the object under test 5;

[0112] The test object 5 is analyzed in different wavelength bands (λ1, λ2...λ). N In the 3D point cloud image below, assuming that for a certain pixel, the point cloud value in band λ1 is (x1, y1, z1), and the point cloud value in band λ2 is (x2, y2, z3), λ N The band point cloud value is (x N ,y N ,z N If the final point cloud value at that pixel is ((x1+x2+……+x), then the final point cloud value at that pixel is ((x1+x2+……+x)). N ) / N, (y1+y2+……+y N ) / N, (z1+z2+……+z N If the point cloud value of a certain band is invalid, then its point cloud value is removed and not included in the calculation.

[0113] Embodiment 2 of the present invention:

[0114] 2. Structured light based on single-frequency phase shift and Gray code

[0115] Similar to the Fourier transform method based on a single image, the average value is calculated by projecting structured light of different bands separately. If the point cloud of a certain band is invalid, it is discarded and not included in the calculation.

[0116] The control and computing board 3 controls the projection system 1 to project an coded structured light of wavelength λ1. Then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the 3D point cloud data of the object under test 5 in the wavelength band λ1.

[0117] The control and computing board 3 controls the projection system 1 to project the same coded structured light at wavelength λ2. Then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the 3D point cloud data of the object under test at wavelength λ2.

[0118] Repeat the above process continuously until the control and calculation board 3 controls the projection system 1. N The same coded structured light is projected at the same wavelength, and then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the λ in this wavelength band. N 3D point cloud data of the object under test 5;

[0119] The test object 5 is analyzed in different wavelength bands (λ1, λ2...λ). N In the 3D point cloud image below, assuming that for a certain pixel, the point cloud value in band λ1 is (x1, y1, z1), and the point cloud value in band λ2 is (x2, y2, z3), λ N The band point cloud value is (x N ,y N ,z N If the final point cloud value at that pixel is ((x1+x2+……+x), then the final point cloud value at that pixel is ((x1+x2+……+x)). N ) / N, (y1+y2+……+y N ) / N, (z1+z2+……+z N If the point cloud value of a certain band is invalid, then its point cloud value is removed and not included in the calculation.

[0120] Embodiment 3 of the present invention:

[0121] 3. Structured light based on multi-frequency phase shift

[0122] Structured light based on multi-frequency phase shifting can certainly be calculated using methods similar to the previous two types of structured light. However, to improve processing speed, multi-band fusion calculation can also be performed using the following method:

[0123] First, the coded structured light at the first frequency f1 uses λ1 band illumination; the coded structured light at the second frequency f2 uses λ2 band illumination; and so on, up to the Nth frequency f1. N The coded structured light uses λ N Band illumination. (Commonly used frequencies include N=3, 5, etc.)

[0124] The decoding calculation method is the same as that used when using monochromatic wavelengths:

[0125] Repeat the above process continuously until the control and calculation board 3 controls the projection system 1. N The same coded structured light is projected at the same wavelength, and then the imaging system 2 acquires the projected image illuminating the object under test 5 and transmits the acquired image to the control and computing board 3 for decoding and calculation to obtain the image at that wavelength (λ). N ) 3D point cloud data of the object under test 5;

[0126] The test object 5 is analyzed in different wavelength bands (λ1, λ2...λ). N In the 3D point cloud image below, assuming that for a certain pixel, the point cloud value in band λ1 is (x1, y1, z1), and the point cloud value in band λ2 is (x2, y2, z3), λ N The band point cloud value is (x N ,y N ,z N If the final point cloud value at that pixel is ((x1+x2+……+x), then the final point cloud value at that pixel is ((x1+x2+……+x)). N ) / N, (y1+y2+……+y N ) / N, (z1+z2+……+z N If the point cloud value of a certain band is invalid, then its point cloud value is removed and not included in the calculation.

[0127] Among them, the 3D point cloud map integrates images from various wavebands, making it more adaptable.

[0128] This invention integrates coded structured light across multiple bands during detection, which can improve the contrast of the reflected image from the object's surface and thus enhance detection accuracy.

[0129] When the structured light projection device projects onto the object under test, the present invention can project multiple structured light images of different wavelengths by modulating the wavelength of the illumination light. Then, during the decoding calculation, the encoded structured light of these different wavelengths is fused together for decoding calculation, which can improve the adaptability of 3D structured light detection, reduce the impact of the color, material and surface roughness of the object under test on the accuracy of 3D detection, and reduce noise and interference.

[0130] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0131] Furthermore, terms such as "horizontal" and "vertical" do not imply that the component must be absolutely horizontal or vertical, but rather that it can be slightly tilted.

[0132] For example, "horizontal" simply means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0133] Furthermore, the terms “first,” “second,” etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or the number of technical features indicated.

[0134] Therefore, features specified as "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0135] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood through the specific circumstances.

[0136] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0137] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-spectral based structured light measurement method, characterized in that, The measurement system comprises a projection system (1), an imaging system (2), a control and operation board card (3) and a PC (4), the control and operation board card (3) is connected with the projection system (1) and the imaging system (2) in control respectively, and the control and operation board card (3) is connected with the PC (4) in control, the projection system (1) is used for projecting coded structured light image; the imaging system (2) is used for collecting the structured light image modulated by the object (5), so as to facilitate the subsequent image processing of the control and operation board card (3); the control and operation board card (3) controls the projection system (1) to project the coded structured light image on one hand, processes the image collected by the imaging system (2) on the other hand, so as to obtain the 3D point cloud of the object (5), and the final 3D point cloud operation result is transmitted to the PC (4) on the other hand; the PC (4) is used for displaying and post-processing the 3D point cloud data; The measurement method comprises the following steps: Step S1, the control and operation board card (3) controls the projection system (1) to project the coded structured light with wavelength λ i ; Step S2, the projection system (1) projects the coded structured light with wavelength λ i to the surface of the object (5) to be measured; Step S3, the imaging system (2) shoots the image modulated by the object (5); Step S4, the control and operation board card (3) carries out Fourier transform on the collected image to obtain 3D point cloud data of the measured object (5) in the λ i wave band; Step S5: For each pixel of the object under test (5), fuse its different wavelength bands of λ. i 3D point cloud maps to improve the quality of 3D point clouds; Step S6, the control and operation board card (3) transmits the fused 3D point cloud data to the PC (4) for display and post-processing.

2. The multi-spectral based structured light measurement method of claim 1, wherein, The projection system (1) projects multiple coded structured light, and the imaging system (2) synchronizes with the projection system (1) during image acquisition.

3. The multi-spectral based structured light measurement method of claim 1, wherein, The illumination light source of the projection system (1) is wide spectrum.

4. The multi-spectral based structured light measurement method of claim 1, wherein, The control and operation board card (3) carries out 3D point cloud fusion point by point according to the 3D point cloud data (x i , y i , z i ) calculated under different wave bands for each pixel position (x, y) of the object (5) to obtain the final 3D point cloud image.

5. The multi-spectral based structured light measurement method of claim 1, wherein, The structured light is based on the Fourier transform of a single image or based on single-frequency phase shift and Gray code, and specifically comprises the following steps: Step S1, the control and operation board card (3) controls the projection system (1) to project coded structured light with wavelength λ1, then the imaging system (2) collects the projection image irradiated to the object (5) and transmits the collected image to the control and operation board card (3) for decoding calculation, so as to obtain the 3D point cloud data of the object (5) under the wavelength λ1; Step S2, the control and operation board card (3) controls the projection system (1) to project the same coded structured light under wavelength λ2, then the imaging system (2) collects the projection image irradiated to the object (5) and transmits the collected image to the control and operation board card (3) for decoding calculation, so as to obtain the 3D point cloud data of the object (5) under the wavelength λ2; Step S3, continuously repeat the above process until the control and operation board card (3) controls the projection system (1) to project the same coded structured light under the wavelength λ N , and then the imaging system (2) collects the projection image irradiated to the measured object (5) and transmits the collected image to the control and operation board card (3) for decoding calculation to obtain the 3D point cloud data of the measured object (5) under the wavelength λ N . Step S4, integrate the 3D point cloud diagram of the test object (5) under different wave bands (λ1, λ2……λ N ). Assuming that for a certain pixel point cloud, the λ1 wave band point cloud value is (x1, y1, z1), the λ2 wave band point cloud value is (x2, y2, z3), and the λ N wave band point cloud value is (x N , y N , z N ), then the final point cloud value at this pixel is ((x1+x2+……+x N ) / N, (y1+y2+……+y N ) / N, (z1+z2+……+z N ) / N). When the point cloud value of a certain wave band is invalid, it is excluded from the calculation.

6. The multi-spectral based structured light measurement method of claim 1, wherein, The structured light is based on multi-frequency phase shift, and specifically comprises the following steps: Step S1, first, the coded structured light under the first frequency f1 uses λ1 waveband illumination, the coded structured light under the second frequency f2 uses λ2 waveband illumination, …, the coded structured light under the Nth frequency f uses λN waveband illumination. N N waveband illumination;​ Step S2, continuously repeat the above process until the control and operation board card (3) controls the projection system (1) to project the same coded structured light under λ N Wavelength, and then the imaging system (2) collects the projection image irradiated to the measured object (5) and transmits the collected image to the control and operation board card (3) for decoding calculation to obtain the 3D point cloud data of the measured object (5) under the wavelength λ N . Step S3, integrate the 3D point cloud diagram of the test object (5) under different wave bands (λ1, λ2, … λ N ). Assuming that for a certain pixel point cloud, the λ1 wave band point cloud value is (x1, y1, z1), the λ2 wave band point cloud value is (x2, y2, z3), and the λ N wave band point cloud value is (x N , y N , z N ), then the final point cloud value at this pixel is ((x1+x2+…+x N ) / N, (y1+y2+…+y N ) / N, (z1+z2+…+z N ) / N). When the point cloud value of a certain wave band is invalid, it is excluded from the calculation.

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