Method and System for Suppressing Strong Mutual Reflection Based on Polarization Complementary Logic Encoding

Abstract

The present disclosure relates to a method and system for suppressing strong mutual reflection based on polarization complementary logic coding. The method includes: obtaining calibration parameters of a camera and a projector; generating polarization phase-shifted fringes based on the calibration parameters, designing high-frequency complementary logic codewords, and embedding the high-frequency complementary logic codewords into the polarization channels through polarization modulation to obtain a composite fringe pattern; calculating a degree of linear polarization map from the collected multi-angle polarization images, extracting high-reflection regions from the degree of linear polarization map using an adaptive threshold segmentation method, and performing binarization processing on the degree of linear polarization map to obtain a binarized degree of linear polarization mask; constraining the decoding range of the high-reflection regions based on the binarized degree of linear polarization mask, decoding the composite fringe pattern to obtain absolute phase order information, and suppressing noise in the absolute phase order information using an adaptive threshold algorithm. The method of the present disclosure can effectively solve the influence of mutual reflection and high dynamic range on the surface of the object to be measured, and improve the accuracy and stability of three-dimensional reconstruction.

Description

Technical Field

[0001] The present disclosure relates to the field of optical three-dimensional measurement technology, and particularly to a method and system for suppressing strong mutual reflection based on polarization complementary logic coding. Background Art

[0002] Fringe projection profilometry (FPP) is a non-contact optical three-dimensional measurement technology. In this technology, a structured light fringe is projected onto the surface of an object by a projector, and then the deformed fringe image generated by the object's topography is captured by a camera. After processing such as phase extraction, phase unwrapping, and system calibration, the three-dimensional geometric information of the object is reconstructed. Due to its fast measurement speed, high accuracy, and excellent resolution, FPP has been widely applied in fields such as industrial inspection, reverse engineering, and digitalization of cultural heritage.

[0003] In existing three-dimensional reconstruction technologies, complex optical phenomena often exist on the surface of the object to be measured, especially the problem of strong mutual reflection. Specifically, due to factors such as irregular shapes, high reflectivity, and unevenness on the object surface, incident light often undergoes multiple reflections and scattering between multiple surfaces, resulting in partial mixing of light rays. This multi-path reflection phenomenon not only causes obvious phase jumps in the captured image but also introduces additional noise and edge blurring, greatly reducing the reconstruction accuracy of traditional methods based on fringe coding and phase unwrapping techniques.

[0004] Currently, common solutions mainly attempt to alleviate the interference caused by mutual reflection through local filtering or global optimization. However, these methods usually cannot fundamentally eliminate the phase ambiguity and noise interference caused by multiple reflections, especially in complex lighting and high-reflection scenarios, where the effect is limited. In addition, some methods may cause loss of image details or damage to edge information during the processing, further affecting the accuracy of the reconstruction result. Summary of the Invention

[0005] To solve the problems of phase ambiguity caused by multiple reflections, phase jumps, and noise interference caused by mutual reflection in traditional methods based on fringe coding and phase unwrapping. The present disclosure proposes a method for suppressing strong mutual reflection based on polarization complementary logic coding to solve the above problems.

[0006] According to one aspect of the present disclosure, there is provided a method for suppressing strong mutual reflection based on polarization complementary logic coding, including:

[0007] S10. Obtain the calibration parameters of the camera and the projector, where the calibration parameters are obtained by projecting a phase-shifting pattern and a Gray code pattern onto a calibration board;

[0008] S20. Generate polarization phase-shifting fringes based on the calibration parameters, design high-frequency complementary logic codewords, and embed the high-frequency complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization coding and high-frequency complementary logic codewords;

[0009] S30. Obtain the collected multi-angle polarization images, calculate the degree of linear polarization map from the multi-angle polarization images, extract the high-reflection regions from the degree of linear polarization map using an adaptive threshold segmentation method, and perform binarization processing on the degree of linear polarization map to obtain a binarized degree of linear polarization mask, where the multi-angle polarization images are obtained by reflecting the composite fringe pattern from the object surface;

[0010] S40. Constrain the decoding range of the high-reflection regions based on the binarized degree of linear polarization mask, decode the composite fringe pattern to obtain absolute phase order information, and use an adaptive threshold algorithm to suppress noise in the absolute phase order information.

[0011] Preferably, after step S40, it further includes: performing phase unwrapping on the absolute phase order information and generating a three-dimensional reconstruction point cloud based on the calibration parameters.

[0012] Preferably, obtaining the calibration parameters of the camera and the projector includes: calibrating the parameters of the camera and the projector according to the projected phase-shifting pattern and Gray code pattern, and then determining the mapping relationship between pixel coordinates and three-dimensional space.

[0013] Preferably, generating polarization phase-shifting fringes based on the calibration parameters includes: filtering out the specular reflection light interference through an orthogonal polarizer, and generating polarization phase-shifting fringes in combination with the polarization phase-shifting structured light equation, where the polarization phase-shifting structured light equation is:

[0014] ,

[0015] In the formula, is the background light intensity, is the fringe modulation degree, is the phase value caused by the surface of the object to be measured, N is the total number of phase-shifting steps, n is the index of the n th phase-shifting map.

[0016] Preferably, designing high-frequency complementary logic codewords and embedding the complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization coding and high-frequency complementary logic codewords includes: designing complementary logic codewords using high-frequency patterns, matching the codeword period with the defocus blur function, and embedding the complementary logic codewords into the polarization modulation channel to associate the codeword intensity with the local polarization response characteristics.

[0017] Preferably, the linear polarization degree map is binarized to obtain a binarized linear polarization degree mask, including: calculating a dynamic threshold based on the local linear polarization degree feature, comparing each pixel value of the linear polarization degree map with the dynamic threshold, and generating a binarized linear polarization degree mask that marks the high-reflection region, expressed as:

[0018] ,

[0019] wherein, is the area threshold function, is the area size of.

[0020] Preferably, the absolute phase order information is phase-unwrapped, expressed as:

[0021] ,

[0022] wherein, is the truncated phase, is the fringe order synthesized by the first four patterns, is the fringe order synthesized by the last four patterns.

[0023] According to one aspect of the present disclosure, a strong mutual reflection suppression system based on polarization complementary logic coding is provided, including:

[0024] a calibration parameter acquisition module, which acquires the calibration parameters of the camera and the projector, wherein the calibration parameters are obtained by projecting phase-shifting patterns and Gray code patterns onto a calibration board;

[0025] a composite fringe pattern calculation module, which generates polarization phase-shifting fringes based on the calibration parameters, designs high-frequency complementary logic codewords, and embeds the high-frequency complementary logic codewords into the polarization channels through polarization modulation to obtain a composite fringe pattern that combines polarization coding and high-frequency complementary logic codewords;

[0026] a binarized linear polarization degree mask acquisition module, which acquires the collected multi-angle polarization images, calculates the linear polarization degree map from the multi-angle polarization images, extracts the high-reflection region from the linear polarization degree map by using an adaptive threshold segmentation method, and binarizes the linear polarization degree map to obtain a binarized linear polarization degree mask, wherein the multi-angle polarization images are obtained by reflecting the composite fringe pattern from the object surface;

[0027] an absolute phase order information noise suppression module, which constrains the decoding range of the high-reflection region based on the binarized linear polarization degree mask, decodes the composite fringe pattern to obtain the absolute phase order information, and suppresses the noise of the absolute phase order information by using an adaptive threshold algorithm.

[0028] According to one aspect of the present disclosure, there is provided an electronic device, including: a processor; a memory for storing processor-executable instructions; wherein, the processor is configured to: execute the above-mentioned method for suppressing strong mutual reflection based on polarization complementary logic coding.

[0029] According to one aspect of the present disclosure, there is provided a computer-readable storage medium, on which computer program instructions are stored, and when the computer program instructions are executed by a processor, the above-mentioned method for suppressing strong mutual reflection based on polarization complementary logic coding is implemented.

[0030] Compared with the prior art, the beneficial effects of the present disclosure are as follows:

[0031] 1) By dynamically estimating the linear polarization degree and real-time adjusting the polarization direction of the projected fringes, the present disclosure can accurately identify and suppress mutual reflection noise and high-dynamic regions, thereby greatly improving the coding signal-to-noise ratio and providing cleaner image data for subsequent 3D reconstruction.

[0032] 2) The composite coding strategy of combining polarization coding with high-frequency complementary logic codewords in the present disclosure can not only effectively resist stripe blur caused by defocus, but also suppress specular highlights, ensuring the stability and accuracy of the coded information under complex lighting conditions; the polarization phase-shifted fringes can reduce environmental stray light or reflection interference and improve the signal-to-noise ratio.

[0033] 3) In the coding stage, the present disclosure designs a special polarization complementary logic pattern, and uses the difference of polarized light on different reflection paths to separate the main reflection signal and the secondary mutual reflection interference; in the decoding stage, an optimized algorithm is used to process the image data to further reduce the phase jump and noise interference caused by mutual reflection, thereby realizing high-precision and robust 3D reconstruction.

[0034] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and do not limit the present disclosure.

[0035] According to the following detailed description of exemplary embodiments with reference to the accompanying drawings, other features and aspects of the present disclosure will become clear. Description of the Drawings

[0036] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification. These drawings show embodiments consistent with the present disclosure and, together with the specification, are used to explain the technical solutions of the present disclosure.

[0037] Figure 1 Flowchart showing the method for suppressing strong mutual reflection based on polarization complementary logic coding;

[0038] Figure 2 Schematic diagram showing the phase-shifted Gray code pattern for determining the internal and external parameters of the projector and the camera in the examples of the present disclosure;

[0039] Figure 3 Shows a schematic diagram of the pattern for three-dimensional reconstruction of the object under test in the examples of the present disclosure;

[0040] Figure 4 Shows a schematic diagram of complementary logic noise in the examples of the present disclosure;

[0041] Figure 5 Shows a schematic diagram of the experimental error analysis results of the standard metal gauge block in the examples of the present disclosure;

[0042] Figure 6 Shows a schematic diagram of the three-dimensional reconstruction results of the complex metal experiment in the examples of the present disclosure;

[0043] Figure 7 Shows a block diagram of the system for suppressing strong mutual reflection based on polarization complementary logic coding in the embodiments of the present disclosure. Detailed implementation manners

[0044] The following will describe in detail various exemplary embodiments, features and aspects of the present disclosure with reference to the accompanying drawings. The same reference numerals in the drawings denote elements having the same or similar functions. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0045] The special term "exemplary" herein means "serving as an example, embodiment or illustration". Any embodiment described as "exemplary" herein does not have to be construed as superior or better than other embodiments.

[0046] The term "and / or" herein merely describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the term "at least one" herein means any one of a plurality or any combination of at least two of a plurality. For example, including at least one of A, B, and C can represent any one or more elements selected from the set composed of A, B, and C.

[0047] In addition, in order to better illustrate the present disclosure, numerous specific details are given in the following detailed implementation manners. Those skilled in the art should understand that the present disclosure can also be implemented without some specific details. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail in order to highlight the gist of the present disclosure.

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0049] Embodiment 1

[0050] Based on the above idea, the present invention proposes a method for suppressing strong mutual reflection based on polarization complementary logic coding. Figure 1 The flowchart showing the method for suppressing strong mutual reflection based on polarization complementary logic coding is shown. The method includes:

[0051] S10. Obtain the calibration parameters of the camera and the projector, where the calibration parameters are obtained by projecting a phase-shifting pattern and a Gray code pattern onto a calibration board;

[0052] S20. Generate polarization phase-shifting fringes based on the calibration parameters, design high-frequency complementary logic codewords, and embed the high-frequency complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization coding and high-frequency complementary logic codewords;

[0053] S30. Obtain the collected multi-angle polarization images, calculate the degree of linear polarization map from the multi-angle polarization images, extract the high-reflection regions from the degree of linear polarization map using an adaptive threshold segmentation method, and perform binarization processing on the degree of linear polarization map to obtain a binarized degree of linear polarization mask, where the multi-angle polarization images are obtained by reflecting the composite fringe pattern from the surface of the object;

[0054] S40. Constrain the decoding range of the high-reflection regions based on the binarized degree of linear polarization mask, decode the composite fringe pattern to obtain the absolute phase order information, and perform noise suppression on the absolute phase order information using an adaptive threshold algorithm.

[0055] The embodiments of the present disclosure provide a method for suppressing strong mutual reflection based on polarization complementary logic coding. Through multi-step collaborative processing, the original image is gradually transformed into a high-precision three-dimensional point cloud. The core process is as follows: First, a camera-projector system with an orthogonal polarization configuration is used to collect a sequence of images of the target object modulated by a polarization complementary logic composite coding pattern. Among them, the original image contains polarization phase-shifted fringes and high-frequency complementary logic codewords (such as XOR coding patterns); the wrapped phase is extracted from the polarization phase-shifted fringes; further, the degree of linear polarization (DOLP) is calculated, the high-reflection region is segmented and dynamically binarized, and the obtained binarization result is used to distinguish the effective signal and noise regions; Secondly, the high-frequency complementary logic pattern (such as XOR coding) is decoded, and the XOR operation result is converted into a Gray code. The decoding process needs to combine polarization information to avoid codeword confusion caused by mutual reflection; Then, an adaptive threshold algorithm and area threshold filtering are used to eliminate isolated noise and uneven illumination interference in the decoded image. The image after eliminating the decoded image retains the effective coding region, providing clean data for phase unwrapping; Combining the decoded Gray code with polarization constraints, the wrapped phase is robustly unwrapped to eliminate jump errors. Finally, the phase is converted into a three-dimensional point cloud through calibration parameters to complete the reconstruction. The method for suppressing strong mutual reflection based on polarization complementary logic coding includes the following steps:

[0056] S10. Obtain the calibration parameters of the camera and the projector, where the calibration parameters are obtained by projecting a phase-shift pattern and a Gray code pattern onto a calibration board.

[0057] In this embodiment, the optical centers of the projector and the camera are placed on the same horizontal line and aligned with the object to be measured. The angle between them is about 10°, and the distance is about 15 cm. First, place the circular calibration board at the object to be measured and adjust the focal lengths of the camera and the projector to ensure that the edges of the dots are clearly visible. Next, project 36 phase-shift Gray code patterns as shown in Figure 2 By taking n groups (n>6) of patterns, the internal and external parameters of the system can be calculated, thereby completing the calibration and establishing the geometric relationship between the camera and the projector.

[0058] To improve the measurement accuracy, the system needs to be accurately calibrated during the acquisition process. The calibration process includes the calibration of the camera's internal and external parameters to ensure the accurate mapping between the camera coordinate system and the world coordinate system; at the same time, the projection fringes of the projector also need to be calibrated to ensure the correspondence between the acquired image data and the projection fringes, providing accurate geometric information for subsequent three-dimensional reconstruction. According to the projected phase-shift pattern and Gray code pattern, the parameters of the camera and the projector are calibrated, and then the mapping relationship between the pixel coordinates and the three-dimensional space is determined as:

[0059] ,

[0060] In the formula, , are the pixel coordinates after the three-dimensional points are projected onto the image plane, , and are the point coordinates in the three-dimensional space relative to the camera coordinate system, , is the product of the focal length and the pixel scaling, , are the principal point coordinates, that is, the position of the image center in the pixel coordinates, is the camera internal parameter matrix.

[0061] In this embodiment, the projector is an LCD projector, and the polarization state of its output is linearly polarized light. According to Malus' law, by placing polarizers at different angles to receive the target pattern, the influence of the reverse specular mutual reflection light is effectively filtered by rotating the polarizer by 90 degrees.

[0062] The reverse-rotating specular reflection light is expressed as:

[0063] ,

[0064] In the formula, is the angle of the camera at the polarizer, is the angle of the projector at the polarizer, represents the phase, is the intensity of the counterclockwise rotation component.

[0065] The forward-rotating specular reflection light is expressed as:

[0066] ,

[0067] In the formula, is the phase, usually zero, is the intensity of the clockwise rotation component.

[0068] The light intensity formula received by the camera is:

[0069] ,

[0070] In the formula, is the unpolarized light component.

[0071] Adopt a time-sharing multi-frame coding acquisition strategy, and capture the three-dimensional information of the object to be measured by designing 7 groups of structured light coding patterns with specific phase relationships. Combine complementary logic modulation technology to construct a dual constraint relationship between light intensity and polarization state in the time dimension, and at the same time use the principle of polarization interference to suppress the specular reflection component at the physical layer. By establishing a multi-frame coding light intensity response model, the primary reflection signal on the target surface and the multiple mutual reflection interference signals can be effectively separated, significantly reducing the problem of excessive local dynamic range caused by differences in the optical properties of the material surface.

[0072] S20. Generate polarization phase-shifted fringes based on the calibration parameters, design high-frequency complementary logic codewords, and embed the high-frequency complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern that combines polarization coding and high-frequency complementary logic codewords.

[0073] Many traditional measurement techniques usually assume ideal conditions in the measurement environment and ignore the effects of mutual reflection and local saturation. However, in complex measurement objects and challenging environments, the global illumination effect will significantly reduce the accuracy and performance of structured light technology. To solve this problem, a common method is to use polarization technology, which can significantly improve the anti-interference ability of structured light measurement. Another widely adopted solution is to set the frequency of the projection pattern higher than the optical transmission bandwidth of the measurement scene. The complementary logic coding method aims to increase the frequency of the coding pattern to reduce the influence of multiple reflections on the metal surface. The method proposed in this embodiment combines their advantages, filters out the specular reflection light rotating in the reverse direction through orthogonal polarization, and at the same time uses the polarization phase-shift technology to achieve full polarization coding.

[0074] In the embodiments of the present disclosure, by adjusting the polarization direction and the design of high-frequency complementary logic codewords, the coding fringes are projected onto the surface of the target object to generate a hybrid coding fringe pattern with high anti-interference ability, ensuring that the image quality can still be effectively controlled under complex illumination. Among them, 10 composite fringe patterns for the three-dimensional reconstruction of the object to be measured are as Figure 3 shown.

[0075] The intensity of the three-step phase-shifted sine fringe image is:

[0076] ,

[0077] where is the average light intensity, is the fringe modulation degree, is the phase value caused by the surface of the object to be measured.

[0078] Different from traditional black and white fringes, polarization phase-shifted fringes are adopted in this embodiment. The polarization beam splitting technology can separate the object light and the reference light, reduce environmental stray light or reflection interference, and improve the signal-to-noise ratio. Since and All are vectors. After superposition it is:

[0079] ,

[0080] In the formula, is the Stokes light intensity parameter of the horizontal polarization state of the projector, is the Stokes light intensity parameter of the vertical polarization state of the projector.

[0081] The specular reflection light interference is filtered out by an orthogonal polarizer, and polarization phase-shifted fringes are generated in combination with the polarization phase-shifted structured light equation. The polarization phase-shifted structured light equation is:

[0082] ,

[0083] In the formula, is the background light intensity, is the fringe modulation degree, is the phase value caused by the surface of the object to be measured, N is the total number of phase shift steps, n is the n index of the -th phase shift image.

[0084] In the embodiments of the present disclosure, by fusing polarization characteristic analysis and high-frequency complementary logic coding, the problems of mutual reflection and high dynamic range on the surface of the object to be measured in a complex illumination environment are effectively solved. The core steps are as follows: collecting a polarization image sequence of the target by using a linear polarizer group; making a polarization complementary logic pattern; designing a polarization-complementary logic composite coding.

[0085] The color information is processed based on complementary logic operations. Its basic principle is to regard the value of each color channel (RGB) as a binary number and utilize the characteristics of complementary logic operations: for two binary bits, if they are the same, the output is 0, and if they are different, the output is 1. Let A and B be two color pixel points, and their RGB components are respectively represented as and . The color complementary logic operation is independently performed on each channel:

[0086] ,

[0087] In the formula, is the value of the red channel of point A, is the value of the red channel of point B, is the value of the green channel of point A, is the value of the green channel of point B, is the value of the blue channel of point A, is the value of the blue channel of point B.

[0088] In color XOR logic processing, the value of each color channel is first converted into the corresponding 8-bit binary representation. Subsequently, the XOR logic operation is performed bit by bit on the binary values of the corresponding channels of two pixel points to generate a new binary result. Then, the XOR logic result of each channel is converted back from the binary form to the decimal value, and finally, a new RGB color value is constructed. This process is independently completed on each color channel, effectively realizing the encoding and processing of color information.

[0089] Furthermore, in combination with polarization encoding and high-frequency complementary logic codewords, the complementary logic encoding method aims to increase the frequency of the encoding pattern to reduce the influence of mutual reflection and high dynamic range; the polarization encoding effectively reduces the interference of ambient light. Combining the two to generate composite encoding fringes greatly improves the robustness to ambient light interference and reduces the influence of mutual reflection on three-dimensional reconstruction.

[0090] Design high-frequency complementary logic codewords, and embed the complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization encoding and high-frequency complementary logic codewords, including: designing complementary logic codewords using high-frequency patterns, matching the codeword period with the defocus blur function, embedding the complementary logic codewords into the polarization modulation channel, and correlating the codeword intensity with the local polarization response characteristics. The frequencies of different patterns are related in the following way:

[0091] ,

[0092] wherein, is the frequency of the pattern after pattern conversion, is the sine fringe frequency of the pattern, is the template frequency of the pattern, N is the total number of steps of phase shift.

[0093] To avoid errors caused by local light saturation, the frequency of the projected pattern must comply with the limiting condition .

[0094] Since the polarization complementary logic encoding has high-frequency information, using image enhancement technology can effectively reduce the noise generated during subsequent complementary logic decoding, and mutual reflection often leads to local image saturation. The method in this embodiment can effectively eliminate these interference information and provide a clean data basis for subsequent encoding.

[0095] S30. Obtain the collected multi-angle polarization images, calculate the degree of linear polarization map from the multi-angle polarization images, extract the high-reflection region from the degree of linear polarization map using the adaptive threshold segmentation method, and perform binarization processing on the degree of linear polarization map to obtain a binarized degree of linear polarization mask, wherein the multi-angle polarization images are obtained by reflecting the composite fringe pattern from the object surface.

[0096] In this embodiment, by processing the collected polarization image, the degree of linear polarization of each pixel is calculated. The degree of linear polarization reflects the polarization degree of light and can effectively distinguish the reflection characteristics of different regions on the surface. By calculating the degree of linear polarization value, the high-reflection region is identified, and further, the adaptive threshold segmentation method is used to remove the influence of mutual reflection noise on the image.

[0097] The high-reflection region is identified through threshold segmentation to suppress mutual reflection noise. The degree of linear polarization is a physical quantity characterizing the state of polarized light and is used to describe the degree of linear polarization at a specific azimuth angle. Specifically:

[0098] ,

[0099] In the formula, is the maximum light intensity, is the minimum light intensity.

[0100] Using the collected polarization image, the degree of linear polarization of each pixel point is calculated, and the high-reflection region is accurately identified by using the adaptive threshold segmentation method.

[0101] Since the polarization complementary logic coding has high-frequency information, the image enhancement technology can effectively reduce the noise generated during the subsequent complementary logic decoding. And mutual reflection often leads to local image saturation. This method can effectively eliminate these interference information and provide a clean data basis for the subsequent coding.

[0102] Based on the distribution of the degree of linear polarization, the polarization direction of the projection stripe is dynamically adjusted to optimize the signal-to-noise ratio of the target region. Specifically:

[0103] ,

[0104] In the formula, is the light intensity of the exclusive-OR pattern at a polarization angle of 90 degrees, is the light intensity of the exclusive-OR pattern at a polarization angle of 0 degrees.

[0105] S40. Based on the binary linear polarization degree mask to constrain the decoding range of the high-reflection region, the composite stripe pattern is decoded to obtain the absolute phase order information, and the adaptive threshold algorithm is used to suppress the noise of the absolute phase order information.

[0106] In this embodiment, the binarized pattern is decoded by the complementary pattern, and then the adaptive threshold algorithm is used to suppress the noise of the image with Gray code modulation. To solve the possible errors that may occur when converting the captured exclusive-OR pattern into a Gray code pattern, this embodiment proposes to reduce the interference in the image through noise suppression to ensure the accuracy of the pattern, and then use the area threshold function to remove the errors caused by uneven illumination and noise, thereby improving the conversion accuracy and robustness.

[0107] When converting the captured complementary logic pattern into a Gray code pattern, compensation or adjustment is required to ensure the accuracy of the final coding result. This is because during the actual coding process, the complementary logic pattern may be affected by noise, ambient light, or other interference factors, resulting in a deviation between the generated pattern and the ideal coding. As Figure 4 shown, if these errors are not corrected, they may cause errors during the subsequent decoding process, affecting the overall accuracy. By correcting these errors, the compensation step ensures that the final Gray code pattern can better reflect the original information, optimizing the efficiency and accuracy of the subsequent decoding process.

[0108] Dynamically adjust the binarization threshold according to the local degree of linear polarization value to eliminate edge noise during the complementary logic decoding process and compensate for the codeword blur caused by defocusing. Specifically:

[0109] ,

[0110] wherein, is the binarized image function, is the noise area generated by the XOR fringes, is the area region function.

[0111] Binarize the degree of linear polarization map to obtain a binarized degree of linear polarization mask, including: calculating a dynamic threshold based on the local degree of linear polarization characteristics, comparing each pixel value of the degree of linear polarization map with the dynamic threshold, and generating a binarized degree of linear polarization mask that marks the high-reflection region, expressed as:

[0112] ,

[0113] wherein, is the area threshold function, is the area size of.

[0114] After step S40, perform phase unwrapping on the absolute phase order information and generate a three-dimensional reconstruction point cloud based on the calibration parameters.

[0115] In this embodiment, the encoded fringes are solved by a phase unwrapping algorithm to restore the phase information on the surface of the target object. During the phase unwrapping process, a constraint term is added to suppress the phase jump problem caused by multipath reflection and mutual reflection, thereby improving the accuracy and stability of phase solving. Perform phase unwrapping on the absolute phase order information, expressed as:

[0116] ,

[0117] wherein, is the truncated phase, is the fringe order synthesized from the first four patterns, is the fringe order synthesized from the last four patterns.

[0118] Specifically, and The interval between them is half a period. Only the period order in the interval is used for the assignment of the truncated phase, while the period order in the interval is used for the value taking of other parts. In this way, it can effectively avoid using the period order, thus fundamentally eliminating the jump error caused by the phase period coding error.

[0119] In the embodiment of the present disclosure, experiments are carried out on the metal cylinder and the metal gauge block to verify, Figure 5 show the reconstruction results of the gauge block. Fit the standard plane of the metal plate, and the RMSE values obtained by using three reconstruction methods are 0.2749, 0.1899 and 0.1475 respectively. Among them, the measurement error of this embodiment is Figure 5 as shown in (g) of, the error distribution is the smallest, and the RMSE is 0.1475. Figure 6 Show the reconstruction results of this embodiment and the traditional complementary Gray code for complex metals. Experiments prove that the embodiment of the present disclosure can reconstruct objects with high robustness.

[0120] Embodiment 2

[0121] As another aspect of the embodiment of the present disclosure, a strong mutual reflection suppression system 100 based on polarization complementary logic coding is further provided, as Figure 7 shown, including:

[0122] A calibration parameter acquisition module 1, which acquires the calibration parameters of the camera and the projector, wherein the calibration parameters are obtained by projecting the phase shift pattern and the Gray code pattern onto the calibration plate;

[0123] A composite fringe pattern calculation module 2, which generates polarization phase shift fringes based on the calibration parameters, designs high-frequency complementary logic codewords, and embeds the high-frequency complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization coding and high-frequency complementary logic codewords;

[0124] A binary linear polarization degree mask acquisition module 3, which acquires the multi-angle polarization images collected, calculates the linear polarization degree map through the multi-angle polarization images, extracts the high-reflection region from the linear polarization degree map by using the adaptive threshold segmentation method, and performs binary processing on the linear polarization degree map to obtain a binary linear polarization degree mask, wherein the multi-angle polarization images are obtained by reflecting the composite fringe pattern from the object surface;

[0125] The absolute phase order information noise suppression module 4 decodes the composite fringe pattern to obtain absolute phase order information based on the binarized degree of linear polarization mask to constrain the decoding range of the high-reflection region, and uses an adaptive threshold algorithm to suppress the noise of the absolute phase order information.

[0126] Without contradiction, the above modules in the system of the embodiments of the present disclosure can implement any implementation manner of the above method.

[0127] Based on the description of the above embodiments, the embodiments of the present disclosure can achieve the following technical effects:

[0128] 1) By dynamically estimating the degree of linear polarization and adjusting the polarization direction of the projected fringes in real time, the present disclosure can accurately identify and suppress mutual reflection noise and high-dynamic regions, thereby greatly improving the coding signal-to-noise ratio and providing cleaner image data for subsequent 3D reconstruction.

[0129] 2) The composite coding strategy of combining polarization coding with high-frequency complementary logic codewords in the present disclosure can not only effectively resist stripe blur caused by defocusing, but also suppress specular highlights, ensuring the stability and accuracy of the encoded information under complex lighting conditions; the polarization phase-shifted fringes can reduce environmental stray light or reflection interference and improve the signal-to-noise ratio.

[0130] 3) In the encoding stage, the present disclosure designs a special polarization complementary logic pattern, utilizes the difference of polarized light on different reflection paths to separate the main reflection signal from the secondary mutual reflection interference; in the decoding stage, an optimized algorithm is used to process the image data to further reduce the phase jump and noise interference caused by mutual reflection, thereby realizing high-precision and robust 3D reconstruction.

[0131] The embodiments of the present disclosure also propose an electronic device, including: a processor; a memory for storing processor-executable instructions; wherein, the processor is configured to perform the above method for suppressing strong mutual reflection based on polarization complementary logic coding. Among them, the electronic device can be provided as a terminal, a server or other forms of devices.

[0132] The embodiments of the present disclosure also propose a computer-readable storage medium, on which computer program instructions are stored, and when the computer program instructions are executed by a processor, the above method for suppressing strong mutual reflection based on polarization complementary logic coding is implemented. The computer-readable storage medium can be a non-volatile computer-readable storage medium.

[0133] Those skilled in the art can understand that in the above method and system for suppressing strong mutual reflection based on polarization complementary logic coding in the specific implementation manner, the writing order of each step does not mean a strict execution order and constitutes any limitation to the implementation process, and the specific execution order of each step should be determined according to its function and possible internal logic.

[0134] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a portion of an instruction, which contains one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions noted in the blocks may occur in an order different from that noted in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented by a dedicated hardware-based system that performs the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0135] The embodiments of the present disclosure have been described above. The above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art in the field of the present technology without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, the practical application, or the technical improvement of the technology in the market, or to enable other ordinary skill in the art in the field of the present technology to understand the embodiments disclosed herein.

Claims

1. A method for suppressing strong mutual reflection based on polarization complementary logic coding, characterized in that, It includes the following steps: S10. Obtain the calibration parameters of the camera and the projector, where the calibration parameters are obtained by projecting a phase-shift pattern and a Gray code pattern onto a calibration board; S20. Generate polarization phase-shift fringes based on the calibration parameters, design high-frequency complementary logic codewords, and embed the high-frequency complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization coding and high-frequency complementary logic codewords; S30. Obtain the acquired multi-angle polarization images, calculate the degree of linear polarization map from the multi-angle polarization images, extract the high-reflection region from the degree of linear polarization map by using an adaptive threshold segmentation method, and perform binarization processing on the degree of linear polarization map to obtain a binarized degree of linear polarization mask, where the multi-angle polarization images are obtained by reflecting the composite fringe pattern from the object surface; S40. Constrain the decoding range of the high-reflection region based on the binarized degree of linear polarization mask, decode the composite fringe pattern to obtain absolute phase order information, and use an adaptive threshold algorithm to suppress the noise of the absolute phase order information.

2. The method according to claim 1, wherein After step S40, it further includes: performing phase unwrapping on the absolute phase order information, and generating a three-dimensional reconstruction point cloud based on the calibration parameters.

3. The method according to claim 1, wherein Obtaining the calibration parameters of the camera and the projector includes: calibrating the parameters of the camera and the projector according to the projected phase-shift pattern and Gray code pattern, and then determining the mapping relationship between pixel coordinates and the three-dimensional space.

4. The method according to any one of claims 1 or 3, characterized in that, Generating polarization phase-shift fringes based on the calibration parameters includes: filtering out the specular reflection light interference through an orthogonal polarizer, and generating polarization phase-shift fringes in combination with the polarization phase-shift structured light equation, where the polarization phase-shift structured light equation is: ， Wherein, is the background light intensity, is the fringe modulation degree, is the phase value caused by the surface of the object to be measured, N is the total number of phase shift steps, n is the n index of the -th phase shift image.

5. The method according to claim 1, characterized in that, Designing high-frequency complementary logic codewords and embedding the complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization coding and high-frequency complementary logic codewords includes: designing complementary logic codewords by using a high-frequency pattern, matching the codeword period with the defocus blur function, and embedding the complementary logic codewords into the polarization modulation channel to associate the codeword intensity with the local polarization response characteristics.

6. The method according to claim 1, characterized in that, Performing binarization processing on the degree of linear polarization map to obtain a binarized degree of linear polarization mask includes: calculating a dynamic threshold based on the local degree of linear polarization characteristics, comparing each pixel value of the degree of linear polarization map with the dynamic threshold, and generating a binarized degree of linear polarization mask marking the high-reflection region, expressed as: ， In the formula, is the area threshold function, is the area size of.

7. The method according to claim 2, wherein Performing phase unwrapping on the absolute phase order information, expressed as: ， wherein, is the truncated phase, is the fringe order synthesized by the first four patterns, is the fringe order synthesized by the last four patterns.

8. A system for suppressing strong mutual reflection based on polarization complementary logic coding, characterized in that, It includes: A calibration parameter acquisition module that obtains the calibration parameters of the camera and the projector, where the calibration parameters are obtained by projecting a phase-shift pattern and a Gray code pattern onto a calibration board; A composite fringe pattern calculation module that generates polarization phase-shift fringes based on the calibration parameters, designs high-frequency complementary logic codewords, and embeds the high-frequency complementary logic codewords into the polarization channel through polarization modulation to obtain a composite fringe pattern integrating polarization coding and high-frequency complementary logic codewords; The binary linear polarization degree mask acquisition module acquires the collected multi-angle polarization images, calculates the linear polarization degree map from the multi-angle polarization images, extracts the high-reflection regions from the linear polarization degree map by using an adaptive threshold segmentation method, and performs binary processing on the linear polarization degree map to obtain a binary linear polarization degree mask, wherein the multi-angle polarization images are obtained by reflecting the composite fringe pattern from the surface of the object; The absolute phase order information noise suppression module constrains the decoding range of the high-reflection regions based on the binary linear polarization degree mask, decodes the composite fringe pattern to obtain the absolute phase order information, and uses an adaptive threshold algorithm to suppress the noise of the absolute phase order information.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the strong mutual reflection suppression method based on polarization complementary logic coding according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the strong mutual reflection suppression method based on polarization complementary logic coding according to any one of claims 1 to 7.

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