A three-dimensional measurement method, device and system based on multi-scale parallel single pixel

Abstract

The present invention relates to the technical field of parallel single-pixel three-dimensional measurement, and in particular to a three-dimensional measurement method, device and system based on multi-scale parallel single-pixel. The present invention divides the image plane of a single-pixel image to be projected into equal parts according to a scale factor, does not change the pixel position of the original direct component, and images and replicates and splices in multiple sub-areas, and converts them into a complete image of the projector's viewing angle. Under the same sampling rate, more accurate imaging results can be obtained by reducing the imaging target surface; at the same time, the present invention reduces the search range on the image plane in the subsequent stereo matching algorithm through depth constraints, and further suppresses aliasing interference caused by replicating sub-areas and splicing imaging in multi-scale imaging, and the constraint can ensure that only sampling in the horizontal and vertical directions of the spectrum is required in imaging, and no slices in additional directions are required, so as to eliminate the ambiguity of the Redon transform. Under the same depth constraint conditions, the present invention can measure continuously and is suitable for the measurement of dynamic scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of parallel single-pixel three-dimensional measurement, and in particular to a three-dimensional measurement method, device and system based on multi-scale parallel single-pixel. Background Art

[0002] Parallel single pixel imaging (PSI) is a recently emerged computational measurement technology that can perform 3D shape reconstruction under strong global illumination based on traditional structured light systems. By extending single pixel imaging (SI) to digital cameras and treating each camera pixel as a single pixel detector, PSI can obtain complete 4D light transmission coefficients for separating complex illumination components and achieving accurate 3D measurement under global illumination. CN110264540A discloses a method for implementing parallel single pixel imaging, which extends the basic method of single pixel imaging to pixel array (image) sensors, greatly broadening the application scope of the single pixel imaging method. First, by projecting and photographing the pattern mode of Fourier slices, the observation area of ​​each pixel on the pixel array is solved and located. Then, the required pattern mode is projected onto the scene using a projector, and the corresponding image is obtained by photographing it with a camera; secondly, the image reconstruction algorithm of parallel single pixel imaging is executed on all pixels on the camera image to obtain an image with the resolution of the projector corresponding to each camera pixel.

[0003] However, a high-precision reconstruction in single-pixel imaging requires a large number of base patterns, which leads to slow reconstruction speed; while SI at low sampling rate has fast reconstruction speed but low reconstruction accuracy. At the same time, various existing improved parallel single-pixel methods are limited to the measurement of static scenes even if they reduce the patterns to a certain extent. Summary of the invention

[0004] In order to overcome the problems of slow reconstruction speed, low reconstruction accuracy, and limitation to measurement of static scenes in existing measurement methods based on parallel single pixels, the present invention provides a three-dimensional measurement method, device and system based on multi-scale parallel single pixels.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a three-dimensional measurement method based on multi-scale parallel single pixel, the method comprising:

[0007] Divide the first single-pixel image into equal parts according to the scale factor to obtain a number of second single-pixel images of equal size;

[0008] Generate a plurality of third single-pixel images of corresponding frequencies according to the spectrum sampling path and sampling points of the second single-pixel image, wherein the third single-pixel images are fringe images with four-step phase shifts;

[0009] Controlling the projection unit to project the third single-pixel image in parallel onto the object to be measured, and controlling the camera unit to shoot to obtain a plurality of first images;

[0010] Calculating the spectral coefficient of each first image according to the third single-pixel image, performing parallel conversion according to the spectral coefficient corresponding to each first image, and generating a corresponding plurality of second images, wherein the second image is a projector viewing angle;

[0011] Copying and splicing each second image according to the scale factor to generate a corresponding number of third images, wherein the third images correspond to the size and position of the first single-pixel image;

[0012] The pixels in each third image are converted in parallel according to the depth constraint, and the world coordinates corresponding to each pixel after the conversion are calculated according to the stereo matching algorithm to generate a three-dimensional point cloud of the object to be measured.

[0013] According to a specific implementation, in the above measurement method, four third single-pixel images form a group, which is expressed as:

[0014] I 1 =a+b cos[2π(f u u p +f v v p )],

[0015] I 2 =a+b cos[2π(f u u p +f v v p )+n / 2],

[0016] I 3 =a+b cos[2π(f u u p +f v v p )+π],

[0017] I 4 =a+b cos[2π(f u u p +f v v p )+3π / 2],

[0018] Among them, I 1 ~I 4 represents a set of spectral coefficients of the third single-pixel image, a is the background light intensity, b is the fringe modulation, u p 、v p is the pixel of the projector target surface, fu 、f v are the frequencies of the third single-pixel image in the horizontal and vertical directions.

[0019] According to a specific implementation, in the above measurement method, the spectral coefficient of each first image is:

[0020] C(f u , f v )=(I 1 -I 3 )+j(I 2 -I 4 ),

[0021] Among them, C(f u , f v ) are the spectral coefficients of the first image.

[0022] According to a specific implementation, in the above measurement method, performing parallel conversion according to the spectral coefficients corresponding to each first image to generate a corresponding plurality of second images includes:

[0023] The spectral coefficients C(f u , f v ) corresponds to the spectral coefficient in the first single-pixel image, which is C(f u ×s,f v ×s), calculate the frequency coefficients point by point on the spectrum, reconstruct part of the spectrum according to the symmetry of the spectrum, and then perform an inverse Fourier transform to obtain the second image, where s is the scale factor.

[0024] According to a specific implementation, in the above measurement method, converting pixels in each third image in parallel according to the depth constraint includes:

[0025] According to the unfolded phase of the depth constraint and the fringe frequency of the third single pixel, the pixel points in each third image are transformed, which is expressed as:

[0026] x p =Φ v (x c ,y c )×P / 2π,

[0027] y p =Φ h (x c ,y c )×P / 2π,

[0028] Among them, x p ,y p is the sub-pixel coordinate corresponding to the pixel point, x c ,y c For xp ,y p Corresponding to the coordinates of the camera screen, Φ v is the horizontal unwrapped phase, Φ h is the unfolding phase in the vertical direction, and P is the fringe frequency of the third single-pixel image.

[0029] According to a specific implementation, in the above measurement method, the depth constraint is:

[0030] The preset pixel points in the camera unit are used with a parallel single pixel method to obtain the preset projection unit viewing angle image corresponding to the preset pixel points at different depths, and the line segment range of the preset pixel points in the preset projection unit viewing angle image constitutes the depth constraint.

[0031] According to a specific implementation, in the above measurement method, calculating the world coordinates corresponding to each pixel point after conversion according to a stereo matching algorithm includes:

[0032] The homography matrix H of the camera unit and the projection unit obtained according to the stereo matching algorithm c , H p , calculate the world coordinates P corresponding to the converted pixel coordinates w =[X w ,Y w ,Z w ] T , expressed as:

[0033]

[0034] Among them, s c is the scale factor at the camera unit end, s p is the scale factor of the projection unit end, X w ,Y w ,Z w is the world position coordinate corresponding to the pixel point w.

[0035] According to a specific implementation, in the above measurement method, each second image is copied and spliced ​​according to the scale factor, which specifically includes: periodically translating and merging and superimposing all the second images in a unified coordinate system.

[0036] In a second aspect, the present invention provides a three-dimensional measurement device based on multi-scale parallel single pixel, characterized in that the device includes at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute any one of the above-mentioned three-dimensional measurement methods based on multi-scale parallel single pixel.

[0037] In a third aspect, the present invention provides a three-dimensional measurement system based on multi-scale parallel single pixel, characterized in that the system includes a projection unit, a camera unit, and the device described above, and the projection unit, the camera unit and the device are communicatively connected.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention divides the image plane of the single-pixel image to be projected into equal parts according to the scale factor, does not change the pixel position of the original direct component, and images and replicates and splices in multiple sub-areas, and converts them into a complete image of the projector's viewing angle, so that more accurate imaging results can be obtained by reducing the imaging target surface at the same sampling rate; at the same time, the present invention reduces the search range on the image plane in the subsequent stereo matching algorithm through depth constraints, and further suppresses the aliasing interference caused by replicating sub-areas and splicing imaging in multi-scale imaging, and the constraint can ensure that only sampling in the horizontal and vertical directions of the spectrum is required in imaging, and no slicing in additional directions is required to eliminate the ambiguity of the Redon transform, which greatly reduces the number of required projection patterns. Further, after other conditions are determined, under the same depth constraint conditions, there is no need to change the scale factor and the projected base pattern according to the changes of the object to be measured in the scene, and continuous measurement can be achieved, which is suitable for the measurement of dynamic scenes. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of an application scenario of an embodiment of the present invention;

[0041] Figure 2 A schematic flow chart of a three-dimensional measurement method based on multi-scale parallel single pixel provided in an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of depth constraint provided by an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of imaging with different scale factors provided by an embodiment of the present invention;

[0044] Figure 5 This is a diagram of three-dimensional measurement results under global effects provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0046] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] The terms "first", "second", etc. in the specification embodiments, claims, and drawings of the present application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, including a series of steps or units. The method, system, product, or device is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0048] It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

[0049] Please refer to Figure 1 , which shows a schematic diagram of an application environment involved in an embodiment of the present invention, the application environment includes a projection unit, a camera unit and a three-dimensional measurement device based on multi-scale parallel single pixels. Figure 1 As shown, the projection unit, the camera unit and the device are communicatively connected, the device transmits the image to be projected to the projection unit, the projection unit projects the image onto the object to be measured, and the camera unit captures the projection image on the object to be measured and transmits it to the device.

[0050] like Figure 1 As shown, the imaging unit is a camera, the projection unit is a projector, the resolution of the projector is 1920×1080 pixels, and the resolution of the camera is 1024×672 pixels.

[0051] Specifically, please refer to Figure 2 , which shows a schematic flow chart of a three-dimensional measurement method based on multi-scale parallel single pixel provided by an embodiment of the present invention, the method comprising:

[0052] Step 1: Divide the first single-pixel image into equal parts according to the scale factor to obtain a number of second single-pixel images of equal size.

[0053] Step 2: Generate a number of third single-pixel images of corresponding frequencies according to the spectrum sampling path and sampling points of the second single-pixel image, wherein the third single-pixel images are fringe images with four-step phase shifts.

[0054] Step 3: Control the projection unit to project the third single-pixel image in parallel onto the object to be measured, and control the camera unit to shoot to obtain a plurality of first images.

[0055] Step 4: Calculate the spectral coefficient of each first image according to the third single-pixel image, perform parallel conversion according to the spectral coefficient corresponding to each first image, and generate a corresponding number of second images, where the second image is the projector viewing angle.

[0056] Step 5: Copy and splice each second image according to the scale factor to generate a corresponding number of third images, where the third images correspond to the size and position of the first single-pixel image.

[0057] Step 6: Convert the pixels in each third image in parallel according to the depth constraint, calculate the world coordinates corresponding to each pixel after conversion according to the stereo matching algorithm, and generate a three-dimensional point cloud of the object to be measured.

[0058] The embodiments of the present invention are further introduced and described below in conjunction with specific implementation methods.

[0059] First, the depth range is explained, such as Figure 3 As shown in the figure, two diffuse reflection standard surfaces Ref 1 and Ref 2 are placed at the nearest and farthest points in the range. The Gray code assisted phase shift method is used to project the corresponding pattern, and the unfolded phases Φv and Φh in the horizontal and vertical directions are calculated on the projector target surface and the camera target surface, respectively. Through bilinear interpolation, the same-name points can be found on the two target surfaces based on the condition that the horizontal and vertical phase values ​​are equal. Figure 3 As shown in the figure, the order of the optical path is projector-diffuse reflection standard surface-camera, and only one diffuse reflection occurs. For any camera pixel point (Pu, Pv), the intersection points of the two optical paths and the two planes are p1 and p2, and the corresponding points on the projector plane are Pp1 and Pp2. After the projector perspective image is generated using the parallel single pixel method, the depth constraint formed by the two standard surfaces corresponds to Figure 3The pixel constraint of the midline segment range is also called the depth constraint.

[0060] According to a specific implementation, as described in step 1 above, the scale factor s is adjusted according to actual conditions. For the first single-pixel image, after the projection pattern area with a pixel size of m×n and the scale factor s are determined, the area is equally divided into sub-areas of size (m / s)×(n / s) in the horizontal and vertical directions, i.e., the second single-pixel image; when the sub-area spectrum sampling path is determined, the projected base pattern will not change. Therefore, within a certain depth range, when other conditions are determined, there is no need to change the projected base pattern according to changes in the object to be measured in the scene, and continuous measurement can be performed, which is suitable for the measurement of dynamic scenes.

[0061] According to a specific implementation, as described in steps 2 to 4 above, Figure 4 (e) The pixel point (u c ,v c ) as an example to illustrate multi-scale parallel single-pixel imaging. This point is located on the metal circular tube and receives energy from the one-time reflection of the optical path projector-metal tube, as well as the influence of mutual reflection and sub-surface scattering in the optical path projector-semi-transparent candle-metal tube under the global effect. The projected base pattern, i.e., the third single-pixel image, has a size of 512×512 and is filled with black to 1920×1080. The scale factor is set to 4, then the size of the second single-pixel image is 128×128, and the spectrum sampling path is set to two sets of slices in the horizontal and vertical directions. In Fourier single-pixel imaging, the spectral coefficient C(f u , f v ), the position and order of the reconstruction coefficients are the spectrum sampling path. Since the important information of natural images is mostly concentrated in the low-frequency part, and the high-frequency information contains more image details, by designing a suitable spectrum sampling path and selectively reconstructing the spectrum, imaging can be achieved with less background patterns without excessive loss of image quality.

[0062] In addition to the common base frequency, each group of slices also needs to sample 5 coefficients to reconstruct the spectrum of the second single-pixel image; according to the point (f u , f v ) Generates a four-step phase shifted base pattern I corresponding to the frequency 1 ~I 4 , i.e. the third single pixel image, and projected onto the surface of the object to be measured. Where a is the background light intensity, b is the fringe modulation, (u p , v p ) is the pixel of the projector target surface, f u and f v Corresponding to the frequencies of the substrate stripes in the horizontal and vertical directions respectively.

[0063] I 1 =a+b cos[2π(f u u p +f v v p )],

[0064] I 2 =a+b cos[2π(f u u p +f v v p )+π / 2],

[0065] I 3 =a+b cos[2π(f u u p +f v v p )+π],

[0066] I 4 =a+b cos[2π(f u u p +f v v p )+3π / 2],

[0067] Among them, I 1 ~I 4 represents a set of spectral coefficients of the third single-pixel image, a is the background light intensity, b is the fringe modulation, u p 、v p is the pixel of the projector target surface, f u 、f v are the frequencies of the third single-pixel image in the horizontal and vertical directions.

[0068] Furthermore, the frequency spectrum point (f u , f v )'s spectral coefficient C(f u , f v )for

[0069] C(f u , f v )=(I 1 -I 3 )+j(I 2 -I 4 ),

[0070] Among them, C(f u , f v ) is the spectral coefficient of the first image. u , f v ) corresponds to the spectral coefficient in the first single-pixel image, which is C(fu ×s,f v ×s), the frequency coefficients are calculated point by point on the spectrum, part of the spectrum is reconstructed according to the spectrum symmetry, and then the second image is obtained by inverse Fourier transform. Specifically, the frequency coefficients are calculated point by point on the spectrum, part of the spectrum is reconstructed according to the spectrum symmetry, and then the second image is obtained by inverse Fourier transform. Since parallel single-pixel imaging satisfies the Helmholtz reciprocity, the image must be the projector's perspective.

[0071] It should be noted that the process of Fourier single-pixel imaging is: projecting a group of base patterns, calculating the spectrum coefficients point by point, reconstructing part of the spectrum, and performing an inverse transformation imaging on the reconstructed spectrum.

[0072] According to a specific implementation, as described in step 5 above, the second image is copied and spliced ​​in an s×s manner into a third image of size 512×512, and restored to the corresponding position of the projector target surface according to the generated base pattern. Figure 4 As shown in (a)-(d), even if the scale factor s changes, the original direct and indirect components will not change their positions, but will be copied and moved to other positions as the sub-areas are copied and spliced. This is because in single-pixel imaging, the complete light transmission coefficient is equal to the sum of the independent light transmission coefficients of each sub-area. Figure 4 Taking (e)-(g) as an example, t(uc,vc)=t1 s+t2 s+t3 s+t4 s. Since the sub-areas in step 2 are divided at equal intervals, the projected base pattern in each sub-area is exactly the same, which can be equivalent to periodically translating and merging all sub-areas in a unified coordinate system. Regardless of whether the direct illumination component is located in the selected reconstruction sub-area, the periodic replication will move it back to the original position, which can completely correspond to the position of parallel single-pixel imaging.

[0073] According to a specific implementation, in the above step 6, the embodiment of the present invention can locate the sub-pixel coordinates (xp, yp) of the original direct component through the epipolar constraint and the depth constraint. It should be noted that the epipolar constraint: in three-dimensional space, direct illumination undergoes only one reflection, and the transmission process is projector lens-object-camera lens, and the transmission light path must be on the epipolar plane; indirect illumination undergoes multiple reflections, and its transmission light path deviates from the epipolar plane. The intersection of the epipolar plane and the projector-camera plane is called the epipolar line. From the image plane, the direct illumination component will be closer to the epipolar line, while the indirect component will be away from the epipolar line. Screening is performed based on the pixel distance from each component to the epipolar line, which is the epipolar constraint. In this step, both constraints are to reduce the search range on the imaging plane and determine the position of the direct illumination component, and the sub-pixel coordinates are extracted using the grayscale centroid method.

[0074] Let (xc, yc) be the sub-pixel coordinates of (xp, yp) corresponding to the camera plane, which has a certain deviation from (uc, vc). (xc, yc) and (xp, yp) are based on the unwrapped phase Φ obtained in step 1. v and Φ h , based on the points of the same name connected by equal phase values ​​in both directions, there exists the following conversion relationship, where P represents the fringe frequency.

[0075] x p =φ v (x c ,y c )×p / 2π,

[0076] y p =Φ h (x c ,y c )×p / 2π,

[0077] Among them, x p ,y p is the sub-pixel coordinate corresponding to the pixel point, x c ,y c For x p ,y p Corresponding to the coordinates of the camera screen, Φ v is the horizontal unwrapped phase, Φ h is the unfolding phase in the vertical direction, and P is the fringe frequency of the third single-pixel image.

[0078] The homography matrix H of the camera unit and the projection unit obtained according to the stereo matching algorithm c , H p , calculate the world coordinates P corresponding to the converted pixel coordinates w =[X w ,Y w ,Z w ] T , expressed as:

[0079]

[0080] Among them, s c is the scale factor at the camera unit end, s p is the scale factor of the projection unit end, X w ,Y w ,Z w is the world position coordinate corresponding to the pixel point w.

[0081] The above linear equations have 6 equations and 5 unknowns: s c ,s p , X w ,Yw ,Z w , which can be solved directly.

[0082] The embodiment of the present invention repeats the imaging and point cloud calculation process of the camera pixel point-projection angle image for all pixels in parallel, so as to establish a complete light transfer function of the measurement scene and obtain the following: Figure 5 The complete point cloud shown in the figure indicates that the present invention can greatly reduce the projection pattern while still achieving good reconstruction effects on diffuse reflection areas, low signal-to-noise ratio areas, strong mutual reflection areas, and sub-surface scattering areas, and can also restore some highly exposed mirror reflection areas.

[0083] In summary, the present invention divides the image plane of the single-pixel image to be projected into equal parts according to the scale factor, does not change the pixel position of the original direct component, and images and replicates and splices in multiple sub-areas, and converts them into a complete image of the projector's viewing angle, so that more accurate imaging results can be obtained by reducing the imaging target surface at the same sampling rate; at the same time, the present invention reduces the search range on the image plane in the subsequent stereo matching algorithm through depth constraints, and further suppresses the aliasing interference caused by replicating sub-areas and splicing imaging in multi-scale imaging, and the constraint can ensure that only sampling in the horizontal and vertical directions of the spectrum is required in imaging, and no slicing in additional directions is required to eliminate the ambiguity of the Redon transform, which greatly reduces the number of required projection patterns. Furthermore, after other conditions are determined, under the same depth constraint conditions, there is no need to change the scale factor and the projected base pattern according to the changes of the object to be measured in the scene, and continuous measurement can be achieved, which is suitable for the measurement of dynamic scenes.

[0084] It should be noted that in an embodiment of the present invention, the camera unit can be implemented by a camera, and the projection unit can be implemented by a projector. In the implementation process, each step of the above method can be completed by an integrated logic circuit of hardware in a processor or an instruction in software form. The steps of the method disclosed in conjunction with the embodiment of the present invention can be directly embodied as being executed by a hardware processor, or can be executed by a combination of hardware and software modules in a processor. The software module can be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in a memory, and the processor reads the information in the memory and completes the steps of the above method in conjunction with its hardware. To avoid repetition, it will not be described in detail here.

[0085] In the embodiments provided in the present application, it should be understood that the disclosed devices, systems and methods can be implemented in other ways. For example, the system described above is only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the device or unit can be electrical, mechanical or other forms.

[0086] Through the description of the above embodiments, it is clear to those skilled in the art that the method in the embodiment of the present application can be implemented by hardware, firmware, or a combination thereof. When software is used for implementation, the above functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on a computer-readable medium. Computer-readable media include computer storage media and communication media, wherein the communication media include any medium that facilitates the transmission of a computer program from one place to another. The storage medium can be any available medium that a computer can access. Taking this as an example but not limited to: a computer-readable medium can include RAM, ROM, an electrically erasable programmable read-only memory (Electrically Erasable Programmable Read Only Memory, EEPROM), a compact disc (Compact Disc Read-Only Memory, CD-ROM) or other optical disc storage, a disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store a desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition. Any connection can be appropriately a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, wireless, and microwave are included in the fixation of the medium. As used in the embodiments of the present application, disks and discs include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks usually copy data magnetically, while discs use lasers to optically copy data. The above combinations should also be included in the scope of protection of computer-readable media.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-dimensional measurement method based on multi-scale parallel single pixel, characterized in that: The method comprises: Divide the first single-pixel image into equal parts according to the scale factor to obtain a plurality of second single-pixel images of equal size; Generate a plurality of third single-pixel images of corresponding frequencies according to the spectrum sampling path and sampling points of the second single-pixel image, wherein the third single-pixel images are fringe images with four-step phase shifts; Controlling the projection unit to project the third single-pixel image in parallel onto the object to be measured, and controlling the camera unit to shoot to obtain a plurality of first images; Calculating the spectral coefficient of each first image according to the third single-pixel image, performing parallel conversion according to the spectral coefficient corresponding to each first image, and generating a corresponding plurality of second images, wherein the second image is a projector viewing angle; Copying and splicing each second image according to the scale factor to generate a number of corresponding third images, wherein the third images correspond to the size and position of the first single-pixel image; Convert the pixels in each third image in parallel according to the depth constraint, calculate the world coordinates corresponding to each pixel after conversion according to the stereo matching algorithm, and generate a three-dimensional point cloud of the object to be measured; The step of converting pixels in each third image in parallel according to the depth constraint comprises: According to the unfolded phase of the depth constraint and the fringe frequency of the third single pixel, the pixel points in each third image are transformed, which is expressed as: ， ， in, , is the sub-pixel coordinate corresponding to the pixel point, , for , Corresponding to the coordinates of the camera screen, is the unwrapped phase in the horizontal direction, is the unwrapped phase in the vertical direction, is the fringe frequency of the third single-pixel image; The depth constraint is: The preset pixel points in the camera unit are used with a parallel single pixel method to obtain the preset projection unit viewing angle image corresponding to the preset pixel points at different depths, and the line segment range of the preset pixel points in the preset projection unit viewing angle image constitutes the depth constraint.

2. The three-dimensional measurement method based on multi-scale parallel single pixel according to claim 1, characterized in that: The four third single-pixel images are grouped as one, expressed as: ， ， ， ， in, ~ represents a set of spectral coefficients of the third single-pixel image, is the background light intensity, For the stripe modulation, , is the pixel of the projector target surface, , are the frequencies of the third single-pixel image in the horizontal and vertical directions.

3. The three-dimensional measurement method based on multi-scale parallel single pixel according to claim 2, characterized in that: The spectral coefficients of each first image are: ， in, are the spectral coefficients of the first image.

4. The three-dimensional measurement method based on multi-scale parallel single pixel according to claim 3, characterized in that: Performing parallel conversion according to the spectral coefficients corresponding to each first image to generate a number of corresponding second images includes: The spectral coefficients of the first image Corresponding to the spectral coefficient in the first single-pixel image, C ( f u × s , f v × s ), calculate the frequency coefficients point by point on the spectrum, reconstruct part of the spectrum according to the symmetry of the spectrum, and then perform an inverse Fourier transform to obtain the second image, where s is the scale factor.

5. The three-dimensional measurement method based on multi-scale parallel single pixel according to claim 1, characterized in that: The world coordinates corresponding to each pixel after conversion are calculated according to the stereo matching algorithm, including: The homography matrix of the camera unit and the projection unit obtained according to the stereo matching algorithm , , calculate the world coordinates corresponding to the converted pixel coordinates P w = [ X w , Y w , Z w ] T , expressed as: ， in, is the scale factor at the camera unit end, is the scale factor at the projection unit end, X w , Y w , Z w is the world position coordinate corresponding to the pixel point w.

6. The three-dimensional measurement method based on multi-scale parallel single pixel according to claim 1, characterized in that: The copying and splicing of each second image according to the scale factor specifically includes: periodically translating, merging and superimposing all the second images in a unified coordinate system.

7. A three-dimensional measurement device based on multi-scale parallel single pixel, characterized in that: The device includes at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the method described in any one of claims 1 to 6.

8. A three-dimensional measurement system based on multi-scale parallel single pixel, characterized in that: The system comprises a projection unit, a camera unit, and the device as claimed in claim 7, wherein the projection unit, the camera unit and the device are communicatively connected with each other.

Images