A method, apparatus, device, and medium for measuring reflective objects.

Abstract

This invention discloses a method, apparatus, device, and medium for measuring reflective objects. The method involves obtaining a second exposure time for the camera based on a set of first deformed fringe patterns acquired by the camera and the time slicing principle; determining the receiving range of each pixel of the camera relative to the pixels of the projector based on a set of second and third deformed fringe patterns acquired by the camera and the Fourier slice theorem; obtaining the reconstructed light transmission coefficient using single-pixel imaging technology on the second and third deformed fringe patterns; determining the direct illumination points of each pixel of the projector based on the reconstructed light transmission coefficient and the depth constraint positioning method; and collecting all direct illumination points to complete the reconstruction of the reflective object image. This method eliminates the need for separate exposure for each image and simultaneously balances image details in both bright and dark areas, thereby reducing the types of exposure times, improving image acquisition efficiency, and enabling the reconstruction of the three-dimensional morphology of low-quality images under low light intensity.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional imaging technology, and in particular to a method, apparatus, device, and medium for measuring reflective objects. Background Technology

[0002] With the development of digital information technology, 3D imaging technology has been widely applied in various fields. 3D imaging technology is a novel technology based on computer vision and image processing. It is a method to obtain the size and shape information of an object by non-contact measurement of its three-dimensional morphology. However, traditional 3D imaging systems generally require the surface of the object being measured to be diffusely reflective. For objects with highly reflective surfaces, the high reflectivity can cause overexposure, resulting in data gaps, or underexposure, causing excessively dark fringes and leading to measurement errors in phase calculation.

[0003] Multiple exposures combine images captured at different exposure times into a single image to avoid image saturation and achieve a high signal-to-noise ratio. The core of multiple exposures lies in acquiring a series of images containing information from regions of varying reflectivity by adjusting the exposure time. Images captured at low exposure times capture useful information from high-reflectivity areas, preventing these areas from losing detail due to overexposure. Conversely, images captured at high exposure times contain useful information from low-reflectivity surface areas, ensuring these areas are not blurred due to underexposure. By merging these images into a set of high dynamic range images, the brightest unsaturated intensity at each pixel can be selected, thereby reconstructing a complete and clear three-dimensional shape.

[0004] Traditional multiple exposure stripe projection technology has the following drawbacks: in order to obtain images with different exposure levels, each image needs to be exposed separately with different exposure times, which limits the choice of exposure time; it is difficult to balance the image details of bright and dark areas when processing high-contrast scenes; low light intensity projection destroys the texture of the reconstructed surface, and the image becomes dark and too noisy, which makes traditional stripe projection enhancement technology almost unusable. Summary of the Invention

[0005] This invention provides a method, apparatus, device, and medium for measuring reflective objects. It eliminates the need for separate exposure for each image and simultaneously balances image details in both bright and dark areas, thereby reducing the variety of exposure times, improving image acquisition efficiency, and enabling three-dimensional morphological reconstruction of low-quality images under low light intensity.

[0006] In a first aspect, embodiments of the present invention provide a method for measuring reflective objects, which is implemented using a device for measuring reflective objects, the device for measuring reflective objects including: a projector and a camera;

[0007] The method for measuring the reflective object includes:

[0008] The projector is controlled to sequentially project a set of Fourier sinusoidal fringe patterns with an exposure time of the first exposure time onto the surface of the reflective object, while the camera is controlled to sequentially acquire a set of first deformed fringe patterns formed on the surface of the reflective object; wherein, a set of Fourier sinusoidal fringe patterns includes four Fourier sinusoidal fringe patterns, the four Fourier sinusoidal fringe patterns have the same fringe order, and the initial phases of the four Fourier sinusoidal fringe patterns are all different; the Fourier sinusoidal fringe patterns include Fourier sinusoidal horizontal fringe patterns and Fourier sinusoidal vertical fringe patterns;

[0009] The second exposure time of the camera is obtained based on a set of first deformable fringe patterns acquired by the camera and the time slicing principle; wherein, the second exposure time is less than the first exposure time;

[0010] The projector is controlled to sequentially project five sets of Fourier sinusoidal horizontal fringe patterns and five sets of Fourier sinusoidal vertical fringe patterns, each with an exposure time equal to the second exposure time, onto the surface of the reflective object. At the same time, the camera is controlled to sequentially acquire five sets of second deformed fringe patterns and five sets of third deformed fringe patterns formed on the surface of the reflective object.

[0011] Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, and the Fourier slice theorem, the receiving range of each pixel of the camera for the pixels of the projector is determined.

[0012] The reconstructed light transmission coefficient is obtained by using single-pixel imaging technology on the second deformed fringe pattern and the third deformed fringe pattern;

[0013] The direct illumination points of the projector pixels are determined one by one based on the reconstructed light transmission coefficient and the depth constraint positioning method.

[0014] By combining all the directly illuminated points, the image of the reflective object is reconstructed.

[0015] Secondly, embodiments of the present invention also provide a measuring device for reflective objects, comprising:

[0016] The image projection and acquisition module is used to control the projector to sequentially project a set of Fourier sinusoidal fringe patterns with an exposure time of the first exposure time onto the surface of the reflective object, and simultaneously control the camera to sequentially acquire a set of first deformed fringe patterns formed on the surface of the reflective object; wherein, the set of Fourier sinusoidal fringe patterns includes four Fourier sinusoidal fringe patterns, the four Fourier sinusoidal fringe patterns have the same fringe order, and the initial phases of the four Fourier sinusoidal fringe patterns are all different; the Fourier sinusoidal fringe patterns include Fourier sinusoidal horizontal fringe patterns and Fourier sinusoidal vertical fringe patterns.

[0017] The second exposure time acquisition module is used to obtain the second exposure time of the camera based on a set of first deformable fringe patterns and the time slicing principle acquired by the camera; wherein the second exposure time is less than the first exposure time;

[0018] The image projection and acquisition module is also used to control the projector to project five sets of Fourier sinusoidal horizontal fringe patterns and five sets of Fourier sinusoidal vertical fringe patterns, each with an exposure time of the second exposure time, onto the surface of the reflective object in sequence, while controlling the camera to sequentially acquire five sets of second deformed fringe patterns and five sets of third deformed fringe patterns formed on the surface of the reflective object.

[0019] The receiving range determination module is used to determine the receiving range of each pixel of the camera to the pixels of the projector based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera and the Fourier slice theorem.

[0020] The reconstructed light transmission coefficient acquisition module is used to obtain the reconstructed light transmission coefficient from the second deformed fringe pattern and the third deformed fringe pattern using single-pixel imaging technology.

[0021] The direct illumination point acquisition module is used to determine the direct illumination point of each pixel of the projector one by one based on the reconstructed light transmission coefficient obtained by the reconstructed light transmission coefficient acquisition module and the depth constraint positioning method.

[0022] The reflective object reconstruction module is used to collect all the direct illumination points acquired by the direct illumination point acquisition module to complete the reconstruction of the reflective object image.

[0023] Thirdly, embodiments of the present invention also provide a measuring device for reflective objects, the measuring device for reflective objects comprising: a projector, a camera, at least one processor; and a memory communicatively connected to the at least one processor;

[0024] The memory stores a computer program that can be executed by the at least one processor, which enables the at least one processor to perform a method for measuring reflective objects as described in any embodiment of the first aspect.

[0025] Fourthly, embodiments of the present invention also provide a computer-readable storage medium storing computer instructions that, when executed by a processor, implement the method for measuring reflective objects as described in any embodiment of the first aspect.

[0026] This invention provides a method, apparatus, device, and medium for measuring reflective objects. It employs time-slicing technology, eliminating the need for individual exposure for each image, reducing the types of exposure times, and improving image acquisition efficiency. Simultaneously, the use of short exposure times and low light intensity avoids overexposure. Based on time-slicing, light transfer coefficient analysis separates direct and indirect lighting points on the projector, effectively overcoming the problem of unusable low-quality images and achieving 3D reconstruction of low-quality images under low light intensity. This invention provides an exposure method that eliminates the need for individual exposure for each image and simultaneously balances image details in both bright and dark areas, thereby reducing the types of exposure times, improving image acquisition efficiency, and achieving 3D morphological reconstruction of low-quality images under low light intensity.

[0027] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A flowchart illustrating a method for measuring reflective objects according to an embodiment of the present invention;

[0030] Figure 2 A schematic diagram of a set of Fourier sine stripe patterns provided for an embodiment of the present invention;

[0031] Figure 3 A schematic diagram of a set of Fourier sinusoidal vertical fringe patterns provided for an embodiment of the present invention;

[0032] Figure 4 A flowchart of another method for measuring reflective objects provided in an embodiment of the present invention;

[0033] Figure 5 A schematic diagram of the structure of a measuring device for reflective objects provided in an embodiment of the present invention;

[0034] Figure 6 This is a schematic diagram of the structure of a measuring device for reflective objects provided in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] Figure 1 This is a flowchart illustrating a method for measuring reflective objects according to an embodiment of the present invention. The method utilizes a reflective object measuring device, which includes a projector and a camera. (Reference) Figure 1 The method for measuring this reflective object includes the following steps:

[0038] S110: Control the projector to project a set of Fourier sine fringe patterns with an exposure time of the first exposure time onto the surface of the reflective object in sequence, and control the camera to collect a set of first deformed fringe patterns formed on the surface of the reflective object in sequence.

[0039] One set of Fourier sine fringe patterns includes four Fourier sine fringe patterns, all four having the same fringe order and different initial phases. The Fourier sine fringe patterns include horizontal and vertical fringe patterns. For example, Figure 2 This is a schematic diagram of a set of Fourier sine fringe patterns provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of a set of Fourier sinusoidal fringe patterns provided in an embodiment of the present invention. It should be noted that the first exposure time can be freely set by the user to produce an overexposure phenomenon in the Fourier sinusoidal fringe pattern.

[0040] Optionally, the Fourier sine bar graph and the Fourier sine bar graph satisfy the following: Among them, P φThe image represents either a horizontal or vertical Fourier sine bar graph, where (u′, ν′) is the number of pixels on the projector, (k, l) is the spatial frequency of the camera, (M, N) is the camera resolution, and φ is the initial phase of the horizontal or vertical Fourier sine bar graph, with values ​​including 0, π / 2, π, and 3π / 2. a represents the average intensity of the horizontal or vertical Fourier sine bar graph, and b represents the contrast. The fringe orders of the five groups of horizontal Fourier sine bar graphs are 8, 16, 24, 32, and 40, respectively; the initial phases of the four horizontal Fourier sine bar graphs in each group are 0, π / 2, π, and 3π / 2, respectively. The fringe orders of the five sets of Fourier sinusoidal vertical fringe plots are 8, 16, 24, 32, and 40, respectively; the initial phases of the four Fourier sinusoidal vertical fringe plots in each set are 0, π / 2, π, and 3π / 2, respectively.

[0041] S120. The second exposure time of the camera is obtained based on a set of first deformed fringe patterns captured by the camera. The second exposure time is shorter than the first exposure time.

[0042] It's important to note that by pixel-by-pixel superimposing grayscale values ​​onto a set of first-dimensional deformable fringe patterns captured by the camera and dividing by 4, the number of pixels for each grayscale value can be obtained. Plotting the pixel counts for each grayscale value yields a histogram. The horizontal axis of the histogram represents the grayscale value (0-255), and the vertical axis represents the number of pixels (i.e., how many pixels represent that grayscale value). Histograms help analyze grayscale variations in an image, thus aiding in determining the optimal grayscale threshold for binarization. If the grayscale values ​​of an object and its background are significantly different, the grayscale histogram will exhibit a bimodal histogram, typically with two peaks representing the foreground and background. The foreground causes a sharp increase in the number of grayscale values ​​in a certain grayscale range, resulting in one peak; similarly, the background causes a sharp increase in the number of grayscale values ​​in another grayscale range, resulting in another peak. The trough between the two peaks corresponds to a relatively small number of target pixels near the object's edge. The minimum value between these two peaks is generally the optimal binarization boundary point, which allows for a clear separation of the foreground and background. In this embodiment, the horizontal coordinate of the first valley of the histogram is defined as the first grayscale value, and the ratio of the maximum grayscale value (255) to the first grayscale value is defined as the optimal number of acquisition groups for the first exposure time. The optimal number of Fourier sine bars is projected using the first exposure time. Since the exposure time for each group of Fourier sine bars is relatively short, this short exposure time is defined as the camera's second exposure time. Acquiring a group of Fourier sine bars using the second exposure time simultaneously balances the exposure of image details in both bright and dark areas, and improves image acquisition efficiency.

[0043] S130: Control the projector to project five sets of Fourier sinusoidal horizontal fringe patterns and five sets of Fourier sinusoidal vertical fringe patterns, each with an exposure time of the second exposure time, onto the surface of the reflective object in sequence. At the same time, control the camera to sequentially collect five sets of second deformed fringe patterns and five sets of third deformed fringe patterns formed on the surface of the reflective object.

[0044] In this embodiment of the invention, time slicing technology is used to set the total exposure time of a set of Fourier sine fringe patterns as the second exposure time, thereby eliminating the need to expose each image separately, reducing the types of exposure times, and improving image acquisition efficiency.

[0045] S140. Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, as well as the Fourier slice theorem, determine the receiving range of each pixel of the camera for the pixels of the projector.

[0046] It should be noted that, based on a set of second and third deformed fringe patterns captured by the camera, and using the Fourier slicing principle, the receiving range of each pixel of the camera relative to the pixels of the projector can be determined. Specifically, firstly, according to the complex transformation rules of the four-step phase-shift projection mode, the first Fourier coefficients of the Fourier sinusoidal horizontal fringe pattern and the second Fourier coefficients of the Fourier sinusoidal vertical fringe pattern can be obtained. Then, a one-dimensional discrete Fourier transform is performed on the first and second Fourier coefficients respectively to obtain the first projection function and the second projection function. Finally, the region where the values ​​of both the first and second projection functions exceed a preset noise threshold is determined as the receiving range of each pixel of the camera relative to the pixels of the projector.

[0047] S150. The reconstructed light transmission coefficient is obtained by using single-pixel imaging technology on the second and third deformed fringe patterns.

[0048] Specifically, firstly, the third Fourier coefficients of the third projection functions of the second and third deformed fringe patterns are obtained according to the Fourier slice theorem. Then, the first optical transmission coefficient is obtained from the third Fourier coefficients using the inverse discrete Fourier transform principle. Finally, the first optical transmission coefficient is introduced into a scaling factor to obtain the reconstructed optical transmission coefficient. It can be understood that by repeating this reconstruction process for each pixel of the camera, the reconstructed optical transmission coefficient containing this scaling factor can be obtained. Therefore, the light rays that originally came from different positions of the light source and were mixed together can be decomposed, providing the premise and foundation for 3D reconstruction under global illumination interference.

[0049] S160. Determine the direct illumination points of the projector pixels one by one based on the reconstructed light transmission coefficient and the depth constraint positioning method.

[0050] Understandably, for any camera pixel, two points can be located on the projection plane, and the direct illumination will lie on the line connecting these two points in the object being measured. This constrains the search area for the direct illumination point to a short line, avoiding ambiguity in dual-image localization and speeding up the search. Specifically, first, Gray coding and phase-shifting methods are used to determine the absolute phase; then, the epipolar line with a limited length is determined based on the absolute phase; finally, the direct illumination point of the projector pixel is determined based on the epipolar line with a limited length.

[0051] S170. Gather all directly illuminated points to reconstruct the image of the reflective object.

[0052] This invention employs time-slicing technology, eliminating the need for individual exposure for each image, reducing the types of exposure times, and improving image acquisition efficiency. Simultaneously, the use of short exposure times and low light intensity avoids overexposure. Based on time-slicing, light transfer coefficient analysis separates direct and indirect lighting points on the projector, effectively overcoming the problem of unusable low-quality images and achieving 3D reconstruction of low-quality images under low light intensity. This invention provides an exposure method that eliminates the need for individual exposure for each image and simultaneously balances image details in both bright and dark areas, thereby reducing the types of exposure times, improving image acquisition efficiency, and achieving 3D morphological reconstruction of low-quality images under low light intensity.

[0053] Figure 4 A flowchart illustrating a method for measuring reflective objects according to an embodiment of the present invention is provided, with reference to... Figure 4 The method for measuring this reflective object includes the following steps:

[0054] S410: Control the projector to project a set of Fourier sine fringes with an exposure time of the first exposure time onto the surface of the reflective object in sequence, and control the camera to collect a set of first deformed fringe patterns formed on the surface of the reflective object in sequence.

[0055] One set of Fourier sine fringe patterns includes four Fourier sine fringe patterns, all of which have the same fringe order and different initial phases; the Fourier sine fringe patterns include Fourier sine horizontal fringe patterns and Fourier sine vertical fringe patterns.

[0056] S420. The second exposure time of the camera is obtained based on a set of first deformed fringe patterns collected by the camera; wherein the second exposure time is less than the first exposure time.

[0057] S430 controls the projector to project five sets of Fourier sinusoidal horizontal fringe patterns and five sets of Fourier sinusoidal vertical fringe patterns, each with an exposure time of the second exposure time, onto the surface of the reflective object in sequence. At the same time, it controls the camera to sequentially acquire five sets of second deformed fringe patterns and five sets of third deformed fringe patterns formed on the surface of the reflective object.

[0058] S440. Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, as well as the Fourier slice theorem, determine the receiving range of each pixel of the camera for the pixels of the projector.

[0059] S450. The reconstructed light transmission coefficient is obtained by using single-pixel imaging technology on the second and third deformed fringe patterns.

[0060] S460. Determine the direct illumination points of the projector pixels one by one based on the reconstructed light transmission coefficient and the depth constraint positioning method.

[0061] S470: Gather all directly illuminated points to reconstruct the image of reflective objects.

[0062] Optionally, based on the above embodiments, continue to refer to... Figure 4 Step S420 includes:

[0063] S421. After superimposing gray values ​​pixel by pixel on a set of first deformed stripe patterns captured by the camera and dividing by 4, the number of pixels for each gray value is obtained.

[0064] S422. Combine the number of pixels for each grayscale value into a histogram.

[0065] S423. Define the x-coordinate of the first valley in the histogram as the first gray value.

[0066] S424. The optimal number of acquisition groups is obtained based on the maximum gray value and the first gray value.

[0067] S425. The second exposure time of the camera is obtained based on the first exposure time and the optimal number of acquisition groups.

[0068] This invention employs histogram analysis to examine grayscale variations in an image. The horizontal coordinate of the first valley in the histogram is defined as the first grayscale value. The ratio of the maximum grayscale value (255) to the first grayscale value is defined as the optimal number of acquisition groups for the first exposure time. The optimal number of acquisition groups is projected using the first exposure time. Since the exposure time for each group of Fourier sine fringes is relatively short, this short exposure time is defined as the camera's second exposure time. Acquiring a group of Fourier sine fringes using the second exposure time simultaneously balances the exposure of image details in both bright and dark areas, thus improving image acquisition efficiency.

[0069] Optionally, based on the above embodiments, step S440 includes:

[0070] S441. Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, calculate the first Fourier coefficients of the first projection function of the second deformed fringe pattern and the second Fourier coefficients of the second projection function of the third deformed fringe pattern according to the Fourier slice theorem.

[0071] Specifically, the first Fourier coefficient Second Fourier coefficient

[0072] in, The first response value of the camera when projecting a Fourier sine fringe pattern onto a reflective object; The second response value of the camera when projecting a Fourier sinusoidal vertical fringe pattern onto a reflective object is φ, which is the initial phase of the Fourier sinusoidal horizontal fringe pattern or the Fourier sinusoidal vertical fringe pattern. The values ​​of φ include 0, π / 2, π, and 3π / 2.

[0073] S442. Perform a one-dimensional discrete Fourier transform on the first Fourier coefficients and the second Fourier coefficients to obtain the first projection function and the second projection function.

[0074] Specifically, the first projection function h x (u′;u,v)=IDFT[H x (k)];The second projection function is h y (u′;u,v)=IDFT[H y (l)]. Where IDFT[·] represents the one-dimensional discrete Fourier transform, H x (k) is the first Fourier coefficient, H y (l) represents the second Fourier coefficient.

[0075] S443. Determine the region where the values ​​of both the first projection function and the second projection function exceed a preset noise threshold as the receiving range of each pixel of the camera for each pixel of the projector.

[0076] For example, the preset noise threshold may include 10. The preset noise threshold can be obtained based on the edge detection theorem, specifically determining the edge boundary based on the abrupt changes in grayscale values.

[0077] Optionally, based on the above embodiments, S450 includes:

[0078] S451. Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, the third Fourier coefficients of the third projection function of the second deformed fringe patterns and the third deformed fringe patterns are calculated according to the Fourier slice theorem.

[0079] Specifically, the third Fourier coefficient Among them, Iφ (u, v; k, l) is the third response value of the camera when projecting a Fourier sine fringe pattern onto a reflective object, and φ is the initial phase of the Fourier sine horizontal fringe pattern or the Fourier sine vertical fringe pattern. The values ​​of φ include 0, π / 2, π, and 3π / 2.

[0080] S452. The reconstructed optical transmission coefficients are obtained based on the principle of discrete Fourier inverse transform.

[0081] Specifically, reconstructing the optical transmission coefficient in, This represents the two-dimensional discrete Fourier inverse transform.

[0082] It should be noted that the reconstructed optical transmission coefficient is the transmission coefficient from any point (u′, ν′) on the projector image plane to a point (u, v) on the camera image plane, with an added scaling factor.

[0083] In this embodiment of the invention, the reconstructed light transmission coefficient is obtained for each pixel of the camera. The light rays that originally came from different positions of the light source and were mixed together can be decomposed, which provides the premise and foundation for three-dimensional reconstruction under global illumination interference.

[0084] Optionally, based on the above embodiments, step S460 includes:

[0085] S461. Determine the absolute phase using Gray coding and phase shifting methods.

[0086] It should be noted that Gray code is a sequence of numbers, each represented in binary, with only one bit differing between any two numbers. Depending on the required number of bits (e.g., 4 bits, 5 bits), a corresponding Gray code fringe pattern is generated. These patterns are projected onto the object being measured. A camera is used to capture the modulated, deformed Gray code fringe pattern of the object. The acquired deformed Gray code fringe pattern, along with the second and third deformed fringe patterns provided in the above embodiments, undergo preprocessing, such as denoising and binarization, to extract useful information. The wrapping phase (relative phase) of each pixel is calculated using the phase-shifting method. The calculated wrapping phase is combined with the corresponding Gray code value, and a specific algorithm (e.g., two's complement) is used to ensure the correct phase shift unfolding, thus obtaining the absolute phase. Using the obtained absolute phase information, combined with system calibration parameters and the principle of trigonometric identities, the three-dimensional coordinates of the object being measured can be calculated, thereby achieving three-dimensional reconstruction.

[0087] S462. Determine the limit polar line based on the absolute phase.

[0088] It should be noted that, according to the Gray coding and phase-shifting methods, the embodiments of the present invention can measure the precise pixel position P of the camera's pixels directly illuminated in the projection plane. p (up v p ), thus based on the point P of the camera pixel in the nearest plane p1 (u p1 v p1 And point P in the farthest plane p2 (u p2 v p2 The constrained polar lines listed can eliminate ambiguous candidates. Among them, Φ v (u c v c ) and Φ h (u c v c ) is m / f u Let n / f be the fringe period of the Fourier sine fringe pattern. v The fringe period is the fringe period of the Fourier sine vertical fringe plot.

[0089] S463. Determine the direct illumination point of the projector's pixels based on the limit polar line.

[0090] It is understandable that the point of direct illumination is located at point P in the nearest plane of the camera pixel. p1 (u p1 v p1 And point P in the farthest plane p2 (u p2 v p2 The constrained epipolar lines listed can constrain the search area of ​​the directly illuminated point to a short line, avoiding ambiguity in dual-image positioning and speeding up the search.

[0091] In summary, this invention employs time-slicing technology, eliminating the need for individual exposure for each image, reducing the types of exposure times, and improving image acquisition efficiency. Simultaneously, the use of short exposure times and low light intensity avoids overexposure. Based on time-slicing, light transfer coefficient analysis separates direct and indirect lighting points on the projector, effectively overcoming the problem of unusable low-quality images and achieving 3D reconstruction of low-quality images under low light intensity. This invention's exposure method, which eliminates the need for individual exposure for each image and simultaneously balances image details in both bright and dark areas, reduces the types of exposure times, improves image acquisition efficiency, and achieves 3D morphological reconstruction of low-quality images under low light intensity. Furthermore, this invention uses histogram analysis to analyze grayscale changes in the image, defining the horizontal coordinate of the first valley of the histogram as the first grayscale value, and defining the ratio of the maximum grayscale value (grayscale value of 255) to the first grayscale value as the optimal number of acquisition groups with the first exposure time. The optimal number of Fourier sine fringe patterns are projected using the first exposure time. Since the exposure time for each group of Fourier sine fringe patterns is relatively short, this short exposure time is defined as the camera's second exposure time. Acquiring a group of Fourier sine fringe patterns using this second exposure time simultaneously balances the exposure of image details in both bright and dark areas, improving image acquisition efficiency. The reconstructed light transmission coefficient is calculated for each pixel of the camera, allowing light rays that were originally mixed together from different locations of the light source to be separated, providing a prerequisite and foundation for 3D reconstruction under global illumination interference. Constraining the search area for directly illuminated points to a short line avoids ambiguity points in dual-image localization and accelerates the search speed.

[0092] Figure 5 This is a schematic diagram of the structure of a measuring device for reflective objects provided in an embodiment of the present invention, with reference to... Figure 5 The device includes: an image projection and acquisition module 510, a second exposure time acquisition module 520, a receiving range determination module 530, a reconstructed light transmission coefficient acquisition module 540, a direct illumination point acquisition module 550, and a reflective object reconstruction module 560.

[0093] In this embodiment of the invention, the image projection and acquisition module 510 is used to control the projector to sequentially project a set of Fourier sinusoidal fringe patterns with an exposure time of the first exposure time onto the surface of the reflective object, while simultaneously controlling the camera to sequentially acquire a set of first deformed fringe patterns formed on the surface of the reflective object; wherein, a set of Fourier sinusoidal fringe patterns includes four Fourier sinusoidal fringe patterns, all four of which have the same fringe order and different initial phases; the Fourier sinusoidal fringe patterns include Fourier sinusoidal horizontal fringe patterns and Fourier sinusoidal vertical fringe patterns. The second exposure time acquisition module 520 is used to obtain the second exposure time of the camera based on a set of first deformed fringe patterns acquired by the camera; wherein, the second exposure time is less than the first exposure time. The image projection and acquisition module 510 is also used to control the projector to sequentially project five sets of Fourier sinusoidal horizontal fringe patterns and five sets of Fourier sinusoidal vertical fringe patterns, each with an exposure time of the second exposure time, onto the surface of the reflective object, while simultaneously controlling the camera to sequentially acquire five sets of second deformed fringe patterns and five sets of third deformed fringe patterns formed on the surface of the reflective object. The receiving range determination module 530 determines the receiving range of each pixel of the camera relative to the pixels of the projector based on a set of second and third deformed fringe patterns acquired by the camera and the Fourier slice theorem. The reconstructed light transmission coefficient acquisition module 540 obtains the reconstructed light transmission coefficients from the second and third deformed fringe patterns using single-pixel imaging technology. The direct illumination point acquisition module 550 determines the direct illumination points of each pixel of the projector based on the reconstructed light transmission coefficients obtained by the reconstructed light transmission coefficient acquisition module and the depth constraint localization method. The reflective object reconstruction module 560 aggregates all direct illumination points obtained by the direct illumination point acquisition module to complete the reconstruction of the reflective object image.

[0094] The reflective object measuring device provided in the embodiments of the present invention can execute the reflective object measuring method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method. For the contents not described in detail in the embodiments of the present invention, please refer to the reflective object measuring device provided in the above embodiments.

[0095] Figure 6 This is a schematic diagram of the structure of a measuring device for reflective objects provided in an embodiment of the present invention, with reference to... Figure 6 This invention also provides a measuring device for reflective objects, including a projector 61, a camera 62, and a processing device 60. Both the projector 61 and the camera 62 are connected to the processing device 60. (Continue to refer to...) Figure 6 The processing device 60 includes a memory 602, a processor 601, and a computer program stored in the memory 602 and executable on the processor. When the processor 601 executes the program, it implements the method described in the above embodiments. Figure 6 A block diagram of an exemplary processing apparatus suitable for implementing embodiments of the present invention is shown. Figure 6 The processing device 60 shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments of the present invention. Figure 6 As shown, the processing device 60 is presented in the form of a general-purpose computing device. The components of the processing device 60 may include, but are not limited to: one or more processors 601, system memory 602, and bus 603 connecting different system components (including system memory 602 and processor 601).

[0096] Bus 603 represents one or more of several bus architectures, including a memory bus or memory controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. For example, these architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0097] Processing device 60 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by processing device 60, including volatile and non-volatile media, removable and non-removable media.

[0098] System memory 602 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 604 and / or cache memory 605. Processing device 60 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 606 may be used to read and write non-removable, non-volatile magnetic media (…). Figure 6 Not shown; usually referred to as a "hard drive"). Although Figure 6 Not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a CD-ROM, DVD-ROM, or other optical media) may be provided. In these cases, each drive may be connected to bus 603 via one or more data media interfaces. System memory 602 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of the present invention.

[0099] A program / utility 608 having a set (at least one) of program modules 607 may be stored, for example, in system memory 602. Such program modules 607 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. Program modules 607 typically perform the functions and / or methods described in the embodiments of the present invention.

[0100] The processing device 60 can also communicate with one or more external devices 609 (e.g., keyboard, pointing device, display 610, etc.), and with one or more devices that enable user interaction with the device, and / or with any device that enables the processing device 60 to communicate with one or more other computing devices (e.g., network interface card, modem, etc.). This communication can be performed via the input / output (I / O) interface 611. Furthermore, the processing device 60 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via the network adapter 612. Figure 6 As shown, network adapter 612 communicates with other modules of processing device 60 via bus 603. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with processing device 60, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0101] The processor 601 executes various functional applications and data processing by running programs stored in the system memory 602.

[0102] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, can implement the methods described in the above embodiments.

[0103] The computer storage medium of this invention can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. For example, a computer-readable storage medium can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0104] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0105] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0106] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages—such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0107] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A method for measuring reflective objects, characterized in that, The measurement is achieved using a reflective object measuring device, which includes a projector and a camera. The method for measuring the reflective object includes: The projector is controlled to sequentially project a set of Fourier sinusoidal fringe patterns with an exposure time of the first exposure time onto the surface of the reflective object, while the camera is controlled to sequentially acquire a set of first deformed fringe patterns formed on the surface of the reflective object; wherein, a set of Fourier sinusoidal fringe patterns includes four Fourier sinusoidal fringe patterns, the four Fourier sinusoidal fringe patterns have the same fringe order, and the initial phases of the four Fourier sinusoidal fringe patterns are all different; the Fourier sinusoidal fringe patterns include Fourier sinusoidal horizontal fringe patterns and Fourier sinusoidal vertical fringe patterns; The second exposure time of the camera is obtained based on a set of first deformed fringe patterns acquired by the camera; wherein the second exposure time is less than the first exposure time; The projector is controlled to sequentially project five sets of Fourier sinusoidal horizontal fringe patterns and five sets of Fourier sinusoidal vertical fringe patterns, each with an exposure time equal to the second exposure time, onto the surface of the reflective object. At the same time, the camera is controlled to sequentially acquire five sets of second deformed fringe patterns and five sets of third deformed fringe patterns formed on the surface of the reflective object. Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, and the Fourier slice theorem, the receiving range of each pixel of the camera for the pixels of the projector is determined. The reconstructed light transmission coefficient is obtained by using single-pixel imaging technology on the second and third deformed fringe patterns. The direct illumination points of the projector pixels are determined one by one based on the reconstructed light transmission coefficient and the depth constraint positioning method. By combining all the directly illuminated points, the image of the reflective object is reconstructed.

2. The method for measuring reflective objects according to claim 1, characterized in that, The Fourier sine horizontal fringe pattern and the Fourier sine vertical fringe pattern satisfy the following: ;in, This refers to either the Fourier sine horizontal fringe plot or the Fourier sine vertical fringe plot. The number of pixels in the projector. The spatial frequency of the camera. The resolution of the camera. The initial phase of the Fourier sine horizontal fringe pattern or the Fourier sine vertical fringe pattern. The values ​​include 0, π / 2, π, and 3π / 2; is the average intensity of the Fourier sine horizontal fringe pattern or the Fourier sine vertical fringe pattern, and b is the contrast of the Fourier sine horizontal fringe pattern or the Fourier sine vertical fringe pattern. The fringe orders of the five groups of Fourier sine fringe patterns are 8, 16, 24, 32, and 40, respectively; the initial phases of the four Fourier sine fringe patterns in each group are 0, π / 2, π, and 3π / 2, respectively. The fringe orders of the five groups of Fourier sinusoidal vertical fringe patterns are 8, 16, 24, 32, and 40, respectively; the initial phases of the four Fourier sinusoidal vertical fringe patterns in each group are 0, π / 2, π, and 3π / 2, respectively.

3. The method for measuring reflective objects according to claim 1, characterized in that, The step of obtaining the second exposure time of the camera based on a set of first deformed fringe patterns acquired by the camera includes: The gray values ​​of each pixel of the first deformed stripe pattern captured by the camera are superimposed and divided by 4 to obtain the number of pixels for each gray value. The number of pixels for each grayscale value is aggregated into a histogram; The x-coordinate of the first valley of the histogram is defined as the first gray value; The optimal number of acquisition groups is determined based on the maximum gray value and the first gray value; The second exposure time of the camera is obtained based on the first exposure time and the optimal number of acquisition groups.

4. The method for measuring reflective objects according to claim 1, characterized in that, The step of determining the receiving range of each pixel of the camera for the pixels of the projector based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, and the Fourier slice theorem, includes: Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, the first Fourier coefficients of the first projection function of the second deformed fringe pattern and the second Fourier coefficients of the second projection function of the third deformed fringe pattern are calculated according to the Fourier slice theorem. The first projection function and the second projection function are obtained by performing a one-dimensional discrete Fourier transform on the first Fourier coefficients and the second Fourier coefficients, respectively. The region where the values ​​of both the first projection function and the second projection function exceed a preset noise threshold is determined as the receiving range of each pixel of the camera for the pixels of the projector.

5. The method for measuring reflective objects according to claim 4, characterized in that, First Fourier coefficient ; Second Fourier coefficient ; The first projection function ; The second projection function is ; in, The first response value of the camera when the Fourier sine fringe pattern is projected onto the reflective object; The response value of the camera when the Fourier sinusoidal fringe pattern is projected onto the reflective object. The initial phase of the Fourier sine horizontal fringe pattern or the Fourier sine vertical fringe pattern. The values ​​of include 0, π / 2, π, and 3π / 2; IDFT[•] represents the one-dimensional discrete Fourier transform.

6. The method for measuring reflective objects according to claim 1, characterized in that, The process of obtaining the reconstructed light transmission coefficient using single-pixel imaging technology on the second and third deformed fringe patterns includes: Based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera, the third Fourier coefficients of the third projection function corresponding to the second deformed fringe patterns and the third deformed fringe patterns are calculated according to the Fourier slice theorem. The reconstructed optical transmission coefficients are obtained based on the principle of inverse discrete Fourier transform.

7. The method for measuring reflective objects according to claim 1, characterized in that, The step of determining the direct illumination points of the projector pixels one by one based on the reconstructed light transmission coefficient and the depth constraint positioning method includes: The absolute phase is determined using Gray coding and phase-shifting methods; The length-limiting polar line is determined based on the absolute phase. The direct illumination point of the projector's pixels is determined based on the defined length polar line.

8. A measuring device for reflective objects, characterized in that, include: The image projection and acquisition module is used to control the projector to sequentially project a set of Fourier sinusoidal fringe patterns with an exposure time of the first exposure time onto the surface of the reflective object, and simultaneously control the camera to sequentially acquire a set of first deformed fringe patterns formed on the surface of the reflective object; wherein, the set of Fourier sinusoidal fringe patterns includes four Fourier sinusoidal fringe patterns, the four Fourier sinusoidal fringe patterns have the same fringe order, and the initial phases of the four Fourier sinusoidal fringe patterns are all different; the Fourier sinusoidal fringe patterns include Fourier sinusoidal horizontal fringe patterns and Fourier sinusoidal vertical fringe patterns. The second exposure time acquisition module is used to obtain the second exposure time of the camera based on a set of first deformed fringe patterns acquired by the camera; wherein the second exposure time is less than the first exposure time; The image projection and acquisition module is also used to control the projector to project five sets of Fourier sinusoidal horizontal fringe patterns and five sets of Fourier sinusoidal vertical fringe patterns, each with an exposure time of the second exposure time, onto the surface of the reflective object in sequence, while controlling the camera to sequentially acquire five sets of second deformed fringe patterns and five sets of third deformed fringe patterns formed on the surface of the reflective object. The receiving range determination module is used to determine the receiving range of each pixel of the camera to the pixels of the projector based on a set of second deformed fringe patterns and a set of third deformed fringe patterns acquired by the camera and the Fourier slice theorem. The reconstructed light transmission coefficient acquisition module is used to obtain the reconstructed light transmission coefficient from the second deformed fringe pattern and the third deformed fringe pattern using single-pixel imaging technology. The direct illumination point acquisition module is used to determine the direct illumination point of each pixel of the projector one by one based on the reconstructed light transmission coefficient obtained by the reconstructed light transmission coefficient acquisition module and the depth constraint positioning method. The reflective object reconstruction module is used to collect all the direct illumination points acquired by the direct illumination point acquisition module to complete the reconstruction of the reflective object image.

9. A measuring device for reflective objects, characterized in that, The measuring device for the reflective object includes: a projector, a camera, at least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which enables the at least one processor to perform the measurement method for reflective objects according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the method for measuring reflective objects according to any one of claims 1-7.

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