Three-dimensional reconstruction method and system based on laser-rotating polygon mirror, and medium

Abstract

The present application relates to a three-dimensional reconstruction method and system based on a laser-rotating polygon mirror, and a medium. The method comprises: acquiring line laser; changing the offset angle of the line laser by synchronously controlling laser power and the rotation angle of a rotating polygon mirror, so as to output a multi-modal laser-encoded pattern; determining a signal compensation amount on the basis of a non-linear relationship between spatial coordinates of an imaging end and the rotation angle, and a coordinate relationship between an initial reflective surface and a rotating reflective surface; compensating the multi-modal laser-encoded pattern on the basis of the signal compensation amount to output a target multi-modal laser-encoded pattern; and reconstructing three-dimensional coordinates on the basis of the target multi-modal laser-encoded pattern. A signal compensation amount is accurately determined by means of a non-linear relationship between spatial coordinates of an imaging end and an offset angle of line laser, and a coordinate relationship between an initial reflective surface and a rotating reflective surface, thereby eliminating measurement deviations caused by system errors or environmental factors.

Description

Three-dimensional reconstruction methods, systems, and media based on laser-multifaceted mirrors

[0001] Related applications

[0002] This application claims priority to Chinese patent application filed on September 2, 2024, application number 202411217566X, entitled "Three-dimensional reconstruction method, system and medium based on laser-multifaceted reflective rotating mirror", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of three-dimensional sensing and measurement technology, and in particular to a three-dimensional reconstruction method, system and medium based on a laser-multifaceted reflective rotating mirror. Background Technology

[0004] Currently, most structured light 3D sensors are based on DLP (Digital Light Processing) projection, which can achieve good results for precision measurements in relatively ideal working environments. However, in complex applications with large fields of view, such as sorting, welding, and gluing in industrial robots, the brightness of DLP is insufficient, thus affecting the 3D measurement results. Complex scenarios include strong ambient light interference and complex materials such as black or highly reflective surfaces on the scanned object. Therefore, it is necessary to develop a structured light 3D sensing and measurement technology that uses laser as the light source.

[0005] In existing technologies, the sensing technologies mainly include laser + MEMS (Micro-Electro-Mechanical System) sensing technology and laser + mechanical galvanometer sensing technology. Laser + MEMS technology has advantages in small size and low cost, but its laser intensity is low and its accuracy is poor. Laser + mechanical galvanometer sensing technology can improve laser intensity and accuracy compared to MEMS, but its scanning speed is limited by the speed of the mechanical galvanometer. Therefore, we propose a laser + high-speed mirror sensing technology to overcome the limitation of galvanometer scanning speed; simultaneously, we propose a multimodal three-dimensional scanning technology to further improve measurement accuracy, robustness, and versatility. Summary of the Invention

[0006] Therefore, it is necessary to propose a three-dimensional reconstruction method, system, and medium based on a laser-multifaceted reflective rotating mirror to address the above problems.

[0007] In a first aspect, this application provides a three-dimensional reconstruction method based on a laser-multifaceted reflector, the method comprising: acquiring a line laser; changing the offset angle of the line laser by synchronously controlling the laser power and the rotation angle of the multifaceted reflector, and outputting a multimodal laser-coded pattern; determining a signal compensation amount based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, and the coordinate relationship between the initial reflecting surface and the rotating reflecting surface; compensating the multimodal laser-coded pattern based on the signal compensation amount, and outputting a target multimodal laser-coded pattern; and reconstructing three-dimensional coordinates based on the target multimodal laser-coded pattern.

[0008] In one embodiment, the signal compensation amount is determined based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, and the coordinate relationship between the initial reflecting surface and the rotating reflecting surface. This includes: determining the multimodal laser coding pattern expression output by the imaging end based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle; determining the input end signal compensation expression based on the relationship between the multimodal laser coding pattern expression and the target output of the imaging end; determining the rotating reflecting surface coordinate model based on the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, according to the input end signal compensation expression; determining the spatial offset based on the rotating reflecting surface coordinate model; determining the line laser offset based on the spatial offset, according to the nonlinear relationship; and substituting the line laser offset into the input end signal compensation expression to determine the signal compensation amount.

[0009] In one embodiment, the spatial offset is:

[0010] Where a is the intercept of the initial reflecting surface in the Cartesian coordinate system; θ is the rotation angle; and d is the vertical distance from the laser source to the center of the reflecting mirror.

[0011] In one embodiment, the line laser offset is:

[0012] Where D is the projected distance of the line laser as it moves along the positive longitudinal axis after being deflected by the initial reflecting surface.

[0013] In one embodiment, the signal compensation amount is:

[0014] in, f1(·) is the signal compensation amount; f1(·) is the target output at the imaging end.

[0015] In one embodiment, the target multimodal laser-coded pattern includes a single-line laser. Reconstructing three-dimensional coordinates based on the target multimodal laser-coded pattern includes: extracting the center of the single-line laser stripe using an image processing algorithm, and determining the sub-pixel precision coordinates of the single-line laser in the image coordinate system; transforming the sub-pixel precision coordinates to the image plane in the camera coordinate system using camera intrinsic parameters; determining the ray from the origin of the image plane to the image point for any image point on the image plane; and reconstructing the three-dimensional coordinates of the image point by determining the spatial intersection of the ray and the single-line laser light plane.

[0016] In one embodiment, the target multimodal laser coding pattern includes multi-line lasers and Gray code; the multi-line lasers include multiple laser lines; reconstructing three-dimensional coordinates based on the target multimodal laser coding pattern includes: encoding the multi-line lasers using Gray code to determine the optical plane parameters of each laser line; determining the optical plane equation of each laser line based on the optical plane parameters; extracting the center of each laser line using an image processing algorithm to determine the sub-pixel precision coordinates of each laser line in the image coordinate system; transforming the sub-pixel precision coordinates corresponding to each laser line to the image plane in the camera coordinate system using camera intrinsic parameters; for each laser line, determining the ray from the origin of the image plane to the image point for any image point on the image plane corresponding to the laser line; and reconstructing the three-dimensional coordinates of the image point by determining the spatial intersection point of the ray and the optical plane equation of the corresponding laser line.

[0017] In one embodiment, the target multimodal laser-coded pattern includes a unidirectional phase-shifted fringe pattern sequence and Gray code; reconstructing three-dimensional coordinates based on the target multimodal laser-coded pattern includes: obtaining a phase-mapping three-dimensional lookup table; solving for the folded phase using the phase-shifting method on the phase-shifted fringe pattern sequence, then decoding using Gray code to determine the order of the folded phase and obtain the absolute phase; querying the mapping coefficient corresponding to each pixel from the phase-mapping three-dimensional lookup table; and determining the reconstructed three-dimensional coordinates of each pixel based on the absolute phase and the mapping coefficient.

[0018] In one embodiment, the reconstructed 3D coordinates of each image point are determined based on the absolute phase and mapping coefficients, including:

[0019] according to Determine the X-axis coordinate of the reconstructed 3D coordinates of each pixel;

[0020] according to Determine the Y-axis coordinate of the reconstructed 3D coordinates of each pixel;

[0021] according to The Z-axis coordinate of the reconstructed 3D coordinates of each pixel;

[0022] Among them, X c Y c and Z cThese are the X-axis coordinates, Y-axis coordinates, and Z-axis coordinates, respectively; a n b n and c n These are the polynomial mapping coefficients for the X-axis, Y-axis, and Z-axis, respectively; c X c Y and c Z All are constant terms; The phase is N; the order of the polynomial is N, and the specific order of the polynomial is n.

[0023] Secondly, this application provides a three-dimensional reconstruction system based on a laser-multifaceted reflection rotating mirror, the system comprising:

[0024] Line laser acquisition module, used to acquire line lasers.

[0025] A multimodal laser-coded pattern output module is used to change the offset angle of the line laser by synchronously controlling the laser power and the rotation angle of the multi-faceted reflector to output a multimodal laser-coded pattern.

[0026] The signal compensation amount determination module is used to determine the signal compensation amount based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface.

[0027] The target multimodal laser coding pattern output module is used to compensate the multimodal laser coding pattern according to the signal compensation amount and output the target multimodal laser coding pattern.

[0028] A three-dimensional coordinate reconstruction module is used to reconstruct three-dimensional coordinates based on the target multimodal laser-coded pattern.

[0029] Thirdly, this application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to perform the steps of the method described in any one of the first aspects.

[0030] The aforementioned 3D reconstruction method, system, and medium based on a laser-multifaceted reflector can flexibly adjust the offset angle of the line laser by synchronously controlling the laser power and the rotation angle of the multifaceted reflector, thereby generating different laser-coded patterns to adapt to different measurement needs. Furthermore, the continuous rotation of the multifaceted reflector can rapidly generate multiple scan lines, improving the efficiency and speed of data acquisition. The generated multimodal laser-coded patterns contain rich multidimensional information, contributing to more accurate reconstruction of 3D coordinates. Further, by considering the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, the signal compensation amount can be accurately calculated, thereby eliminating measurement deviations caused by system errors or environmental factors. Compensation for the multimodal laser-coded pattern is performed based on the signal compensation amount, outputting the target multimodal laser-coded pattern. Furthermore, by processing the target multimodal laser-coded pattern, accurate 3D coordinate data can be generated, enabling 3D visualization of the measured object, improving measurement accuracy, robustness, and universality. The reconstructed 3D coordinate data can be used in many fields, such as industrial automation, robot navigation, 3D printing, and medical imaging, and has broad application prospects. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 is a flowchart illustrating a three-dimensional reconstruction method based on a laser-multifaceted mirror in one embodiment;

[0033] Figure 2 is a schematic diagram of the structure of a laser-multifaceted reflective rotating mirror module in one embodiment;

[0034] Figure 3 is a schematic diagram of laser reflection performed by a multi-faceted reflective rotating mirror in one embodiment;

[0035] Figure 4 is a schematic diagram of laser reflection by a multi-faceted reflective mirror in another embodiment;

[0036] Figure 5 is a Cartesian coordinate diagram of the four-sided reflecting mirror in a Cartesian coordinate system in one embodiment;

[0037] Figure 6 is a flowchart illustrating a three-dimensional reconstruction method based on a laser-multifaceted mirror in another embodiment;

[0038] Figure 7 is a schematic diagram of the multimodal laser coding pattern offset before compensation in one embodiment;

[0039] Figure 8 is a schematic diagram of the planar light intensity spatial distribution of the compensated target multimodal laser coding pattern in one embodiment;

[0040] Figure 9 is a schematic diagram of the multimodal laser coding pattern offset before compensation in another embodiment;

[0041] Figure 10 is a schematic diagram of the planar light intensity spatial distribution of the compensated target multimodal laser coding pattern in another embodiment;

[0042] Figure 11 is a schematic diagram of a three-dimensional reconstruction system based on a laser-multifaceted mirror in one embodiment;

[0043] Figure 12 is a schematic diagram of the structure of the storage medium in one embodiment. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0046] In one embodiment, as shown in Figure 1, a flowchart illustrating a three-dimensional reconstruction method based on a laser-multifaceted rotating mirror is provided. The three-dimensional reconstruction method based on a laser-multifaceted rotating mirror includes:

[0047] S101: Acquisition line laser.

[0048] S102: By synchronously controlling the laser power and the rotation angle of the multi-faceted reflector, the offset angle of the line laser is changed to output a multi-mode laser-coded pattern.

[0049] Referring to Figure 2, which is a schematic diagram of a laser-multifaceted reflective rotating mirror module, the laser-multifaceted reflective rotating mirror consists of a laser emitter 1 (blue light, wavelength 450nm), a line laser beam expander lens group 2, a multifaceted reflective rotating mirror 3, and a control circuit 4. The line laser beam expander lens group 2 includes a Powell prism. The laser emitter 1 emits a line laser, which is expanded by the Powell prism and projected onto the multifaceted reflective rotating mirror 3. The multifaceted reflective rotating mirror 3 includes a rotating mirror motor 31, which deflects at high speed according to the input timing analog voltage signal, rapidly reflecting the line laser into the scene to form a coded pattern. By precisely controlling the input signal waveforms of the laser emitter 1 and the multifaceted reflective rotating mirror 3 through the control circuit 4, different coded patterns can be projected. For each coded pattern, the control circuit 4 synchronously triggers the camera to acquire the image, thereby achieving multimodal high-speed synchronous projection and acquisition integration.

[0050] For example, this application designs an N-sided coated reflective multi-faceted rotating mirror 3. The rotating mirror motor 31 rotates 360° during operation, avoiding the reciprocating vibration of the multi-faceted rotating mirror 3. It scans N times per revolution, increasing the scanning speed by N times compared to the original. As shown in Figures 3 and 4, Figure 3 is a schematic diagram of laser reflection using a multi-faceted rotating mirror, and Figure 4 is a schematic diagram of laser reflection using another multi-faceted rotating mirror. The multi-faceted rotating mirror 3 includes four reflecting mirrors. The laser emitter 1 and the rotation axis of the multi-faceted rotating mirror 3 are at different horizontal positions. The multi-faceted rotating mirror 3 rotates counterclockwise at a certain speed. The laser emitter 1 emits a linear laser beam, which is reflected by one of the surfaces of the multi-faceted rotating mirror 3. The emitted light beam sweeps across the surface to be measured as the reflector rotates. By synchronously controlling the laser power and the multi-faceted rotating mirror 3, an effective scanning range with a field of view (FOV) of 40° is achieved. The rotating mirror motor 31 can achieve four projections in one revolution. Currently, small coreless brushless motors can achieve a rated speed of 15,000 rpm while meeting torque requirements, resulting in a final projection frame rate of 1,000 frames per second.

[0051] S103: Determine the signal compensation amount based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface.

[0052] For example, referring to Figure 5, which is a Cartesian coordinate diagram of a four-sided reflecting mirror in a Cartesian coordinate system, a Cartesian coordinate system is established with the center point O of the four-sided reflecting mirror as the center. The initial angle of the four-sided reflecting mirror forms a 45° angle with the x and y axes, and the intercept is a, serving as the initial reflecting surface. A laser source S emits a linear laser incident ray y = d along the negative x-axis, which is incident on one point of the initial reflecting surface. The reflected light from the line laser travels along the positive y-axis direction D and strikes point P0 on the working surface;

[0053] Assuming a counterclockwise rotation angle θ is positive, as shown in Figure 5, the four-sided reflecting mirror rotates counterclockwise by an angle θ around its center point O, becoming a rotating reflecting surface, intersecting the incident laser ray at point R. off At this moment, the reflection point undergoes a δ = R change on the incident laser beam. on -R off As the line laser moves, the reflected ray rotates by twice the angle θ with the reflecting mirror, intersecting the working surface at point P. off , through R on As R off Parallel lines intersect the working surface at P. on As can be seen, the light rays projected onto the object plane also undergo a shift of δ, which is called spatial offset error.

[0054] Furthermore, the nonlinear relationship between the spatial coordinates of the imaging end and the offset angle of the line laser is determined. First, let the target laser encoding pattern output at the imaging end be I = f1(x). Taking the output cosine variation pattern as an example, when a cosine time series signal, i.e., I..., is input to the laser... in =cost n Since the rotation angle θ is a function of time, denoted as θ = wt n , t n Given a time series and w as the rotational speed of the mirror, the expression for the line laser at the input end can be written as:

[0055] Among them, I in The input line laser intensity is w, the rotation speed of the mirror is θ, and the rotation angle is f. in A is the input signal for the line laser, A is the background intensity, and B is the modulation index.

[0056] Furthermore, the nonlinear relationship between the spatial coordinate x of the imaging end and the rotation angle θ is easily obtained, as shown in the following equation:

[0057] Where x is the spatial coordinate of the imaging end, θ is the rotation angle, and δ is the spatial offset. Let P0 be the x-coordinate of point P0 in spatial coordinates. For P off The x-coordinate of a point in spatial coordinates. For P on The x-coordinate of the point in the spatial coordinate system is given by D, which is the projected distance of the line laser after it is deflected by the initial reflecting surface and moves along the positive direction of the vertical axis.

[0058] It is obvious that the spatial coordinate x at the imaging end has a non-linear relationship with the rotation angle θ. Therefore, the laser-coded pattern formed by the cosine time series signal uniformly sampled at the input end will deviate from the cosine change relationship and be deformed. This deviation is called non-linear error.

[0059] in, Let be a constant, 'a' be the initial intercept of the reflecting surface in the Cartesian coordinate system, and 'd' be the perpendicular distance from the laser source to the center of the reflecting mirror. For multi-faceted reflecting mirrors, δ≠0, and there are both nonlinear errors and spatial offset errors.

[0060] At this point, the multimodal laser-coded pattern expression output at the imaging end can be denoted as:

[0061] Among them, I out f represents the light intensity of the multimodal laser-coded pattern at the input end. in (·) represents the input signal of the line laser, f2(·) represents the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, A represents the background intensity, and B represents the modulation degree.

[0062] Furthermore, based on the multimodal laser coding pattern expression, in order to make the multimodal laser coding pattern output of the imaging surface correspond to the target output I at the imaging end... out =f1(x), then the input signal compensation expression is as follows:

[0063] Furthermore, the coordinate relationship between the initial reflecting surface and the rotating reflecting surface is determined. After the reflecting mirror is rotated counterclockwise by an angle θ, the old coordinates and the new coordinates satisfy the following:

[0064] Where (x, y) are the old coordinates of the initial reflecting surface, and (x′, y′) are the new coordinates of the rotated reflecting surface. When θ = 0, the initial reflecting surface x + y = a is on top, i.e. Where a is the intercept of the initial reflecting surface in the Cartesian coordinate system.

[0065] Furthermore, by substituting the input signal compensation expression into the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, the coordinate model of the rotating reflecting surface can be obtained, as shown in the following formula:

[0066] Furthermore, the spatial offset is determined based on the coordinate model of the rotating reflector. Let the ordinate y′ = d in the coordinate model of the rotating reflector, and then determine the point... As shown in the following formula:

[0067] Where d is the vertical distance from the laser source to the center of the reflecting mirror, and a is the intercept of the initial reflecting surface in the Cartesian coordinate system. For P off The x-coordinate of the point in spatial coordinates, θ is the rotation angle.

[0068] Therefore, referring to Figure 3, the spatial offset δ is given by the following formula:

[0069] Where θ is the rotation angle. For R off The x-coordinate of a point in spatial coordinates. For R on The x-coordinate of the point in the spatial coordinate system, a is the intercept of the initial reflecting surface in the Cartesian coordinate system, and d is the vertical distance from the laser source to the center of the reflecting mirror.

[0070] Furthermore, by substituting the spatial offset into the nonlinear relationship, the line laser offset is determined, as shown in the following formula:

[0071] in, Let P0 be the x-coordinate of point P0 in spatial coordinates. For P off The x-coordinate of the point in the spatial coordinate system, a is the intercept of the initial reflecting surface in the Cartesian coordinate system, d is the vertical distance from the laser source to the center of the reflecting mirror, θ is the rotation angle, and D is the projected distance of the line laser after it is deflected by the initial reflecting surface and moves along the positive direction of the vertical axis.

[0072] Finally, by substituting the line laser offset into the input signal compensation expression, the signal compensation amount can be obtained. The specific expression for the signal compensation amount is shown in the following formula:

[0073] in, denoted as signal compensation, f1(·) is the target output at the imaging end, a is the intercept of the initial reflecting surface in the Cartesian coordinate system, d is the vertical distance from the laser source to the center of the reflecting mirror, θ is the rotation angle, and D is the projected distance of the line laser after it is deflected by the initial reflecting surface and moves along the positive direction of the longitudinal axis.

[0074] S104: Compensate for the multimodal laser coding pattern based on the signal compensation amount, and output the target multimodal laser coding pattern.

[0075] For example, the multimodal laser coding pattern is compensated according to the signal compensation amount. At this time, the output of the imaging end is the preset target multimodal laser coding pattern, which is shown in the following formula:

[0076] Where m is the fringe order, x1 is the left boundary of the laser-multifaceted mirror at the imaging end, x2 is the right boundary of the laser-multifaceted mirror at the imaging end, and x n Let A be the coordinates of the line laser on the imaging plane, and B be the background intensity and the modulation index.

[0077] It should be noted that since the signal compensation is based on the result, it has a compensation effect on both coaxial mechanical galvanometers and multi-faceted rotating mirrors. The difference is that for coaxial mechanical galvanometers, f2 does not contain spatial offset error, δ=0; for multi-faceted rotating mirrors, f2 contains spatial offset error, δ≠0.

[0078] S105: Reconstruct three-dimensional coordinates based on the target's multimodal laser-coded pattern.

[0079] For example, the laser-multifaceted reflector module combines three measurement modes: line scanning of a single-line laser, surface scanning of a multi-line laser and Gray code, and surface scanning of phase-shifted fringes and Gray code. Therefore, the target multimodal laser-coded pattern includes a single-line laser, a multi-line laser and Gray code, as well as a phase-shifted fringe pattern sequence and Gray code.

[0080] Specifically, the main control module controls a laser-multifaceted reflector to project a single-line laser beam, which rapidly scans the object. The camera captures the modulated light from the object's surface. An image processing algorithm extracts the center of the laser beam acquired by the camera, determining its sub-pixel precision coordinates in the image coordinate system. Intrinsic parameters obtained during camera calibration transform the sub-pixel precision coordinates of the single-line laser beam to an image plane with a focal length of 1 in the camera coordinate system. For any image point, it is represented by the origin of the image plane and a ray. By determining the spatial intersection of this ray with the single-line laser beam plane, the three-dimensional coordinates of the image point can be reconstructed.

[0081] The main control module controls the laser-multifaceted reflector to sequentially project multi-line laser and Gray code target multimodal laser coding patterns, quickly scanning the object. Since multiple laser lines exist simultaneously in the same plane, Gray code is used to encode the multiple laser lines, that is, each Gray code value corresponds to one laser line. The parameters of the multi-line laser light plane are determined by the Gray code value, thereby converting the reconstruction of multi-line laser into single-line laser reconstruction.

[0082] The main control module controls a laser-multifaceted reflector to sequentially project a set of unidirectional phase-shifted fringe patterns and Gray code target multimodal laser-coded patterns, rapidly scanning the object while the camera simultaneously acquires images. During calibration, a phase-mapping 3D lookup table is obtained. The phase-shifting method (i.e., the N-step phase-shifting method, where N is greater than or equal to 4) is used to solve for the folded phase on the acquired images. Then, the order of the folded phase is solved using Gray code to unfold and obtain the absolute phase. The mapping coefficient corresponding to each image point is looked up from the lookup table obtained from calibration. Substituting the phase and mapping coefficient into the 3D point calculation formula reconstructs the 3D coordinates.

[0083] As described above, this application, by synchronously controlling the laser power and the rotation angle of the multi-faceted reflecting mirror, can flexibly adjust the offset angle of the line laser, thereby generating different laser coding patterns to adapt to different measurement needs. Furthermore, the continuous rotation of the multi-faceted reflecting mirror can quickly generate multiple scan lines, improving the efficiency and speed of data acquisition. The generated multimodal laser coding pattern contains rich multidimensional information, which helps to more accurately reconstruct the three-dimensional coordinates. Further, by considering the nonlinear relationship between the spatial coordinates of the imaging end and the offset angle of the line laser, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, the signal compensation amount can be accurately calculated, thereby eliminating measurement deviations caused by system errors or environmental factors. Based on the signal compensation amount, the multimodal laser coding pattern is compensated, and the target multimodal laser coding pattern is output. Furthermore, by processing the target multimodal laser coding pattern, accurate three-dimensional coordinate data can be generated, improving measurement accuracy, robustness, and universality. This enables three-dimensional visualization of the measured object, and the reconstructed three-dimensional coordinate data can be used in multiple fields, such as industrial automation, robot navigation, 3D printing, and medical imaging, showing broad application prospects.

[0084] Figure 6 shows a flowchart of another 3D reconstruction method based on a laser-multifaceted mirror. The 3D reconstruction method based on a laser-multifaceted mirror includes:

[0085] S201: Acquisition line laser.

[0086] It should be noted that step S201 has been discussed in detail in the implementation scenario shown in Figure 1, and will not be repeated here.

[0087] S202: By synchronously controlling the laser power and the rotation angle of the multi-faceted reflector, the offset angle of the line laser is changed, and a multi-mode laser coding pattern is output.

[0088] For example, referring to Figure 7, which is a schematic diagram of the multimodal laser-coded pattern offset before compensation. Through simulation modeling, the deformation of the multimodal laser-coded pattern at the imaging end caused by off-axis offset and nonlinear transformation of a four-sided reflecting mirror with a side length of 6mm was tested at a working distance of D = 800mm and a field of view of 40°. Here, NE represents the nonlinear error, and SE represents the spatial offset error. As can be seen from Figure 7, the nonlinear error has a significant impact on the ideal cosine curve, while the spatial offset error has a smaller impact.

[0089] S203: Determine the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle.

[0090] For example, referring to Figure 5, let the target laser coding pattern output in the imaging end be I = f1(x). Taking the output cosine variation pattern as an example, when a cosine time series signal, i.e. I, is input to the laser... in =cost n Since the rotation angle θ is a function of time, denoted as θ = wt n , t n Given a time series and w as the rotational speed of the mirror, the expression for the line laser at the input end can be written as:

[0091] Among them, I in The input line laser intensity is w, the rotation speed of the mirror is θ, and the rotation angle is f. in A is the input signal for the line laser, A is the background intensity, and B is the modulation index.

[0092] Furthermore, the nonlinear relationship between the spatial coordinate x of the imaging end and the rotation angle θ is easily obtained, as shown in the following equation:

[0093] Where x is the spatial coordinate of the imaging end, θ is the rotation angle, and δ is the spatial offset. Let P0 be the x-coordinate of point P0 in spatial coordinates. For P off The x-coordinate of a point in spatial coordinates. For P on The x-coordinate of the point in the spatial coordinate system is given by D, which is the projected distance of the line laser after it is deflected by the initial reflecting surface and moves along the positive direction of the vertical axis.

[0094] S204: Determine the expression of the multimodal laser coding pattern output at the imaging end based on the nonlinear relationship.

[0095] For example, the multimodal laser-coded pattern expression output at the imaging end can be written as:

[0096] Among them, I out f represents the light intensity of the multimodal laser-coded pattern at the input end. in (·) represents the input signal of the line laser, f2(·) represents the nonlinear relationship between the spatial coordinates of the imaging end and the offset angle of the line laser, A represents the background intensity, and B represents the modulation degree.

[0097] S205: Determine the input signal compensation expression based on the relationship between the multimodal laser coding pattern expression and the target output at the imaging end.

[0098] For example, based on the multimodal laser-coded pattern expression, in order to make the multimodal laser-coded pattern of the output of the imaging surface the target output I at the imaging end... out =f1(x), then the input signal compensation expression is as follows:

[0099] S206: Determine the coordinate relationship between the initial reflecting surface and the rotating reflecting surface.

[0100] For example, when the reflecting mirror is rotated counterclockwise by an angle θ, the old coordinates and the new coordinates satisfy:

[0101] Where (x, y) are the old coordinates of the initial reflecting surface, and (x′, y′) are the new coordinates of the rotated reflecting surface, and when θ=0, the initial reflecting surface x+y=a is on top. Where a is the intercept of the initial reflecting surface in the Cartesian coordinate system.

[0102] S207: Based on the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, determine the coordinate model of the rotating reflecting surface according to the input signal compensation expression.

[0103] For example, by substituting the input signal compensation expression into the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, the coordinate model of the rotating reflecting surface can be obtained, as shown in the following formula:

[0104] S208: Determine the spatial offset based on the coordinate model of the rotating reflective surface.

[0105] For example, let the ordinate y′ = d in the coordinate model of the rotating reflective surface, and determine the point. As shown in the following formula:

[0106] Where d is the vertical distance from the laser source to the center of the reflecting mirror, and a is the intercept of the initial reflecting surface in the Cartesian coordinate system. For P off The x-coordinate of the point in spatial coordinates, θ is the rotation angle.

[0107] Therefore, referring to Figure 3, the spatial offset δ is given by the following formula:

[0108] Where θ is the rotation angle. For R off The x-coordinate of a point in spatial coordinates. For R on The x-coordinate of the point in the spatial coordinate system, a is the intercept of the initial reflecting surface in the Cartesian coordinate system, and d is the vertical distance from the laser source to the center of the reflecting mirror.

[0109] S209: Based on nonlinear relationships, determine the linear laser offset according to the spatial offset.

[0110] For example, the spatial offset is substituted into the nonlinear relationship to determine the line laser offset, which is shown in the following formula:

[0111] in, Let P0 be the x-coordinate of point P0 in spatial coordinates. For P off The x-coordinate of the point in the spatial coordinate system, a is the intercept of the initial reflecting surface in the Cartesian coordinate system, d is the vertical distance from the laser source to the center of the reflecting mirror, θ is the rotation angle, and D is the projected distance of the line laser after it is deflected by the initial reflecting surface and moves along the positive direction of the vertical axis.

[0112] S210: Substitute the line laser offset into the input signal compensation expression to determine the signal compensation amount.

[0113] For example, the signal compensation amount can be obtained by substituting the line laser offset into the input signal compensation expression. The specific expression for the signal compensation amount is shown in the following formula:

[0114] in, denoted as signal compensation, f1(·) is the target output at the imaging end, a is the intercept of the initial reflecting surface in the Cartesian coordinate system, d is the vertical distance from the laser source to the center of the reflecting mirror, θ is the rotation angle, and D is the projected distance of the line laser after it is deflected by the initial reflecting surface and moves along the positive direction of the longitudinal axis.

[0115] S211: Compensate for the multimodal laser coding pattern based on the signal compensation amount, and output the target multimodal laser coding pattern.

[0116] For example, based on the compensation formula, the deformation of the laser-multifaceted reflector structure can be corrected. Taking a four-faceted reflector with a side length of 6mm as an example, a simulation was performed at a working distance of 800mm and a field of view of 40°. The compensation result is shown in Figure 8, which is a schematic diagram of the planar light intensity spatial distribution of a compensated target multimodal laser-coded pattern. As can be seen from Figure 8, the curve of the compensated target multimodal laser-coded pattern completely coincides with the ideal cosine curve.

[0117] It should be noted that the target multimodal laser coding pattern proposed in this application can be a cosine wave, a square wave, or other functions, without specific limitations. As shown in Figures 9 and 10, Figure 9 is a schematic diagram of the offset of the multimodal laser coding pattern before compensation, and Figure 10 is a schematic diagram of the spatial distribution of planar light intensity of the target multimodal laser coding pattern after compensation. The multimodal laser coding patterns in Figures 9 and 10 are square wave distributions. During compensation, the nonlinear relationship between the spatial coordinates of the imaging end and the offset angle of the line laser is first determined. Based on the nonlinear relationship, the expression of the multimodal laser coding pattern output at the imaging end is determined. Based on the relationship between the multimodal laser coding pattern expression and the target output at the imaging end, the expression of the input signal compensation is determined. The coordinate relationship between the initial reflecting surface and the rotating reflecting surface is determined. Based on the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, the coordinate model of the rotating reflecting surface is determined according to the expression of the input signal compensation. The spatial offset is determined according to the coordinate model of the rotating reflecting surface. Based on the nonlinear relationship, the linear laser offset is determined according to the spatial offset. The linear laser offset is substituted into the expression of the input signal compensation to determine the signal compensation amount. Furthermore, the multimodal laser coding pattern is compensated according to the signal compensation amount, and the target multimodal laser coding pattern is output. The compensation result of the square wave distribution is shown in Figure 10. The light intensity curve of the imaging end after compensation completely coincides with the ideal intensity curve.

[0118] For a four-sided reflecting mirror with a side length of 6mm, at a working distance of D=800mm and a field of view of 40°, the maximum and minimum values ​​and standard deviations of the spatial offset error SE and nonlinear error NE on the final image grayscale are shown in Table 1. Table 1 shows the influence of spatial offset error and nonlinear error on the final image grayscale.

[0119] Table 1

[0120] S212: Reconstruct three-dimensional coordinates based on the target's multimodal laser-coded pattern.

[0121] For example, the laser-multifaceted reflector module combines three measurement modes: line scanning of a single-line laser, surface scanning of a multi-line laser and Gray code, and surface scanning of phase-shifted fringes and Gray code. Therefore, the target multimodal laser-coded pattern includes a single-line laser, a multi-line laser and Gray code, as well as a phase-shifted fringe pattern sequence and Gray code.

[0122] Specifically, the target multimodal laser coding pattern includes a single-line laser; the center of the single-line laser stripe is extracted using an image processing algorithm to determine the sub-pixel precision coordinates of the single-line laser in the image coordinate system; the sub-pixel precision coordinates are transformed to the image plane in the camera coordinate system using camera intrinsic parameters; for any image point on the image plane, the ray from the origin of the image plane to the image point is determined; and the three-dimensional coordinates of the current image point are reconstructed by determining the spatial intersection point of the ray and the single-line laser light plane.

[0123] The target multimodal laser coding pattern includes multi-line lasers and Gray code; the multi-line lasers include multiple laser lines; Gray code is used to encode the multi-line lasers to determine the optical plane parameters of each laser line; the optical plane equation of each laser line is determined based on the optical plane parameters; image processing algorithms are used to extract the center of each laser line to determine the sub-pixel precision coordinates of each laser line in the image coordinate system; the sub-pixel precision coordinates corresponding to each laser line are transformed to the image plane in the camera coordinate system using camera intrinsic parameters; for each laser line, for any image point on the image plane, a ray from the origin of the image plane to the image point is determined; the three-dimensional coordinates of the image point are reconstructed by determining the spatial intersection point of the ray and the optical plane equation of the corresponding laser line.

[0124] The target multimodal laser-coded pattern includes a unidirectional phase-shifted fringe pattern sequence and Gray code. During calibration, a phase-mapping three-dimensional lookup table is obtained. The phase-shifted fringe pattern sequence is solved using the phase-shifting method (i.e., the N-step phase-shifting method, where N is greater than or equal to 4) to solve for the folded phase. Then, Gray code is used for decoding to determine the order of the folded phase and obtain the absolute phase. The mapping coefficient corresponding to each image point is queried from the phase-mapping three-dimensional lookup table. Based on the absolute phase and the mapping coefficient, the reconstructed three-dimensional coordinates of each image point are determined.

[0125] The X-axis coordinate of the reconstructed 3D coordinates of each pixel is determined according to the following formula:

[0126] The Y-axis coordinate of the reconstructed 3D coordinates of each pixel is determined according to the following formula:

[0127] The Z-axis coordinate of the reconstructed 3D coordinates of each pixel is determined according to the following formula:

[0128] Among them, X c Y c and Z c These are the X-axis coordinates, Y-axis coordinates, and Z-axis coordinates, respectively; a n b n and c n These are the polynomial mapping coefficients for the X-axis, Y-axis, and Z-axis, respectively; c X c Y and c Z All are constant terms; The phase is N; the order of the polynomial is N, and the specific order of the polynomial is n.

[0129] As described above, this application, by considering the nonlinear relationship between the spatial coordinates and rotation angle of the imaging end, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, can accurately calculate the signal compensation amount. This eliminates measurement deviations caused by system errors or environmental factors. Based on the signal compensation amount, multimodal laser-coded patterns are compensated, and a target multimodal laser-coded pattern is output. Furthermore, determining the signal compensation amount improves the accuracy of the measurement data, providing a reliable foundation for subsequent 3D reconstruction. During the 3D reconstruction process, for locally reflective or black areas, supplementary scanning can be performed using line laser area scanning or area scanning to further improve measurement accuracy.

[0130] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0131] Based on the same inventive concept, this application also provides a laser-multifaceted mirror-based 3D reconstruction system for implementing the aforementioned laser-multifaceted mirror-based 3D reconstruction method. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the laser-multifaceted mirror-based 3D reconstruction system provided below can be found in the limitations of the laser-multifaceted mirror-based 3D reconstruction method described above, and will not be repeated here.

[0132] In one embodiment, as shown in Figure 11, which is a schematic diagram of a three-dimensional reconstruction system based on a laser-multifaceted mirror, a three-dimensional reconstruction system 10 based on a laser-multifaceted mirror includes:

[0133] Line laser acquisition module 11 is used to acquire line lasers.

[0134] The multimodal laser coding pattern output module 12 is used to change the offset angle of the line laser by synchronously controlling the laser power and the rotation angle of the multi-faceted reflector, and output a multimodal laser coding pattern.

[0135] The signal compensation amount determination module 13 is used to determine the signal compensation amount based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface.

[0136] The target multimodal laser coding pattern output module 14 is used to compensate for the multimodal laser coding pattern according to the signal compensation amount and output the target multimodal laser coding pattern.

[0137] The three-dimensional coordinate reconstruction module 15 is used to reconstruct the three-dimensional coordinates based on the target multimodal laser-coded pattern.

[0138] For example, in the online laser acquisition module 11, line laser is acquired. Further, in the multimodal laser coding pattern output module 12, the offset angle of the line laser is changed by synchronously controlling the laser power and the rotation angle of the multi-faceted reflecting mirror to output a multimodal laser coding pattern. Further, in the signal compensation amount determination module 13, the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle is determined; the expression for the multimodal laser coding pattern output from the imaging end is determined based on the nonlinear relationship; the input signal compensation expression is determined based on the relationship between the multimodal laser coding pattern expression and the target output from the imaging end; the coordinate relationship between the initial reflecting surface and the rotating reflecting surface is determined; based on the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, the coordinate model of the rotating reflecting surface is determined based on the input signal compensation expression; the spatial offset is determined based on the rotating reflecting surface coordinate model; the line laser offset is determined based on the spatial offset according to the nonlinear relationship; the line laser offset is substituted into the input signal compensation expression to determine the signal compensation amount. Further, in the target multimodal laser coding pattern output module 14, the multimodal laser coding pattern is compensated based on the signal compensation amount, and the target multimodal laser coding pattern is output. Finally, the three-dimensional coordinates are reconstructed in the three-dimensional coordinate reconstruction module 15. Specifically, the target multimodal laser coding pattern includes a single-line laser. The center of the single-line laser stripe is extracted using an image processing algorithm to determine the sub-pixel precision coordinates of the single-line laser in the image coordinate system. The sub-pixel precision coordinates are transformed to the image plane in the camera coordinate system using camera intrinsic parameters. For any image point on the image plane, the ray from the origin of the image plane to the image point is determined. The three-dimensional coordinates of the current image point are reconstructed by determining the spatial intersection point of the ray and the single-line laser light plane.

[0139] The target multimodal laser-coded pattern includes a single-line laser. The center of the single-line laser stripe is extracted using an image processing algorithm to determine the sub-pixel precision coordinates of the single-line laser in the image coordinate system. The sub-pixel precision coordinates are transformed to the image plane in the camera coordinate system using camera intrinsic parameters. For any image point on the image plane, the ray from the origin of the image plane to the image point is determined. The three-dimensional coordinates of the current image point are reconstructed by determining the spatial intersection of the ray and the single-line laser light plane.

[0140] The target multimodal laser coding pattern includes multi-line lasers and Gray code; the multi-line lasers include multiple laser lines; Gray code is used to encode the multi-line lasers to determine the optical plane parameters of each laser line; the optical plane equation of each laser line is determined based on the optical plane parameters; image processing algorithms are used to extract the center of each laser line to determine the sub-pixel precision coordinates of each laser line in the image coordinate system; the sub-pixel precision coordinates corresponding to each laser line are transformed to the image plane in the camera coordinate system using camera intrinsic parameters; for each laser line, for any image point on the image plane, a ray from the origin of the image plane to the image point is determined; the three-dimensional coordinates of the image point are reconstructed by determining the spatial intersection point of the ray and the optical plane equation of the corresponding laser line.

[0141] The target multimodal laser-coded pattern includes a unidirectional phase-shifted fringe pattern sequence and Gray code. During calibration, a phase-mapping three-dimensional lookup table is obtained. The phase-shifted fringe pattern sequence is solved using the phase-shifting method (i.e., the N-step phase-shifting method, where N is greater than or equal to 4) to solve for the folded phase. Then, Gray code is used for decoding to determine the order of the folded phase and obtain the absolute phase. The mapping coefficient corresponding to each image point is queried from the phase-mapping three-dimensional lookup table. Based on the absolute phase and the mapping coefficient, the reconstructed three-dimensional coordinates of each image point are determined.

[0142] Figure 12 is a schematic diagram of a storage medium. The storage medium 20 stores at least one computer program 21, which is executed by a processor to implement the methods shown in Figures 1 and 6. Detailed methods are described above and will not be repeated here. In one embodiment, the storage medium 30 can be a storage chip, hard disk, portable hard disk, USB flash drive, optical disk, or other read / write storage device, or even a server, etc.

[0143] The foregoing has described specific embodiments of this specification; other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than those shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily have to follow the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0144] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the embodiments of apparatus, devices, and non-volatile computer-readable storage media are basically similar to the method embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0145] The apparatus, device, non-volatile computer-readable storage medium and method provided in the embodiments of this specification are corresponding. Therefore, the apparatus, device and non-volatile computer storage medium also have similar beneficial technical effects as the corresponding method. Since the beneficial technical effects of the method have been described in detail above, the beneficial technical effects of the corresponding apparatus, device and non-volatile computer storage medium will not be repeated here.

[0146] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, a computer can be, for example, a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email device, game console, tablet computer, wearable device, or any combination of these devices.

[0147] For ease of description, the above apparatus is described by dividing it into various functional units. Of course, in implementing this specification, the functions of each unit can be implemented in one or more software and / or hardware components. Those skilled in the art will understand that the embodiments of this specification can be provided as methods, systems, or computer program products. Therefore, the embodiments of this specification can take the form of entirely hardware embodiments, entirely software embodiments, or embodiments combining software and hardware aspects. Furthermore, the embodiments of this specification can take the form of computer program products implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0148] This specification is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this specification. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more flowchart illustrations and / or one or more block diagrams.

[0149] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0150] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0151] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0152] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0153] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0154] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0155] This specification can be described in the general context of computer-executable instructions that are executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. This specification can also be practiced in distributed computing environments, where tasks are performed by remote processing devices connected via a communication network. In distributed computing environments, program modules can reside in local and remote computer storage media, including storage devices.

[0156] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0157] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Therefore, any equivalent variations made in accordance with the claims of this application shall still fall within the scope of this application.

[0158] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A three-dimensional reconstruction method based on a laser-multifaceted mirror, characterized in that, The method includes: Acquisition line laser; The offset angle of the line laser is changed by synchronously controlling the laser power and the rotation angle of the multi-faceted reflector to output a multi-mode laser-coded pattern. The signal compensation amount is determined based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface. The multimodal laser coding pattern is compensated according to the signal compensation amount, and the target multimodal laser coding pattern is output. Reconstruct the three-dimensional coordinates based on the target multimodal laser-coded pattern.

2. The method according to claim 1, characterized in that, The step of determining the signal compensation amount based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, and the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, includes: Based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, the expression of the multimodal laser coding pattern output by the imaging end is determined; Based on the relationship between the multimodal laser coding pattern expression and the target output at the imaging end, the input signal compensation expression is determined; Based on the coordinate relationship between the initial reflecting surface and the rotating reflecting surface, the coordinate model of the rotating reflecting surface is determined according to the input signal compensation expression; The spatial offset is determined based on the coordinate model of the rotating reflective surface. Based on the nonlinear relationship, the line laser offset is determined according to the spatial offset; Substitute the line laser offset into the input signal compensation expression to determine the signal compensation amount.

3. The method according to claim 2, characterized in that, The spatial offset is: Where a is the intercept of the initial reflecting surface in the Cartesian coordinate system; θ is the rotation angle; and d is the vertical distance from the laser source to the center of the reflecting mirror.

4. The method according to claim 2, characterized in that, The line laser offset is: Where D is the projected distance of the line laser as it moves along the positive longitudinal axis after being deflected by the initial reflecting surface.

5. The method according to claim 4, characterized in that, The signal compensation amount is: in, f1(·) is the signal compensation amount; f1(·) is the target output at the imaging end.

6. The method according to claim 2, characterized in that, The target multimodal laser-coded pattern includes a single-line laser; the reconstruction of three-dimensional coordinates based on the target multimodal laser-coded pattern includes: Image processing algorithms are used to extract the center of the single-line laser beam and determine the sub-pixel precision coordinates of the single-line laser in the image coordinate system. The subpixel precision coordinates are transformed to the image plane in the camera coordinate system using camera intrinsic parameters. For any image point on the image plane, determine the ray from the origin of the image plane to the image point; reconstruct the three-dimensional coordinates of the image point by determining the spatial intersection of the ray and the single-line laser beam plane.

7. The method according to claim 2, characterized in that, The target multimodal laser-coded pattern includes multi-line lasers and Gray code; the multi-line lasers include multiple laser lines; the reconstruction of three-dimensional coordinates based on the target multimodal laser-coded pattern includes: The Gray code is used to encode the multi-line laser to determine the optical plane parameters of each line laser; The optical plane equation of each line laser is determined based on the optical plane parameters of each line laser. Image processing algorithms are used to extract the center of each line laser beam and determine the sub-pixel precision coordinates of each line laser beam in the image coordinate system. The sub-pixel precision coordinates corresponding to each line laser are transformed to the image plane in the camera coordinate system using camera intrinsic parameters. For each of the line lasers, for any image point on the image plane corresponding to the line laser, a ray from the origin of the image plane to the image point is determined; by determining the spatial intersection point of the ray and the light plane equation of the corresponding line laser, the three-dimensional coordinates of the image point are reconstructed.

8. The method according to claim 2, characterized in that, The target multimodal laser-coded pattern includes a unidirectional phase-shift fringe sequence and Gray code; the reconstruction of three-dimensional coordinates based on the target multimodal laser-coded pattern includes: Obtain the phase-mapping three-dimensional lookup table; The phase-shifting method is used to solve the folded phase of the phase-shifted fringe pattern sequence, and then the Gray code is used for decoding to determine the order of the folded phase and obtain the absolute phase. Query the mapping coefficient corresponding to each image point from the phase-mapping three-dimensional lookup table; The reconstructed 3D coordinates of each image point are determined based on the absolute phase and the mapping coefficients.

9. The method according to claim 8, characterized in that, The step of determining the reconstructed 3D coordinates of each image point based on the absolute phase and the mapping coefficients includes: according to Determine the X-axis coordinate of the reconstructed 3D coordinates of each pixel; according to Determine the Y-axis coordinate of the reconstructed 3D coordinates of each pixel; according to The Z-axis coordinate of the reconstructed 3D coordinates of each pixel; Among them, X c Y c and Z c These are the X-axis coordinates, Y-axis coordinates, and Z-axis coordinates, respectively; a n b n and c n These are the polynomial mapping coefficients for the X-axis, Y-axis, and Z-axis, respectively; c X c Y and c Z All are constant terms; The phase is N; the order of the polynomial is N, and the specific order of the polynomial is n.

10. A three-dimensional reconstruction system based on a laser-multifaceted reflection rotating mirror, characterized in that, The system includes: Line laser acquisition module, used to acquire line lasers; A multimodal laser-coded pattern output module is used to change the offset angle of the line laser by synchronously controlling the laser power and the rotation angle of the multi-faceted reflector to output a multimodal laser-coded pattern. The signal compensation amount determination module is used to determine the signal compensation amount based on the nonlinear relationship between the spatial coordinates of the imaging end and the rotation angle, as well as the coordinate relationship between the initial reflecting surface and the rotating reflecting surface. The target multimodal laser coding pattern output module is used to compensate the multimodal laser coding pattern according to the signal compensation amount and output the target multimodal laser coding pattern. A three-dimensional coordinate reconstruction module is used to reconstruct three-dimensional coordinates based on the target multimodal laser-coded pattern.

11. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, the processor performs the steps of the method as described in any one of claims 1 to 9.

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