A three-dimensional scanning system, a three-dimensional scanning method and a computer readable storage medium

Abstract

The application provides a three-dimensional scanning system, a three-dimensional scanning method and a computer readable storage medium. The system comprises a transmitting end, a receiving end and a processor. The transmitting end transmits a composite line pattern light beam comprising a dense line pattern and a sparse line pattern to a scanned object. Each coded line in the sparse line pattern is at least aligned with part of the measurement lines in the dense line pattern to achieve unique coding. The receiving end collects the composite line pattern light beam reflected by the scanned object and generates left and right composite line images. The left and right composite line images each comprise a dense line image and a sparse line image. The processor decodes the dense line image in the left and right composite line images according to the arrangement number of each coded line in the sparse line image to identify a plurality of measurement lines. The depth information of the scanned object is obtained by using the measurement lines in the identified left and right dense line images for stereo matching. The system provided by the application can obtain high-precision three-dimensional scanning information while reducing the cost.

Description

Technical Field

[0001] This application relates to the field of three-dimensional imaging technology, and in particular to a three-dimensional scanning system, method and computer-readable storage medium. Background Technology

[0002] Existing intraoral 3D scanning systems for teeth typically use digital light processing (DLP) at the transmitter to project a pre-set multi-frame fringe pattern (such as Gray code or phase-shifted fringes) onto the object surface, which can easily achieve high measurement accuracy. However, DLP hardware is expensive and complex in structure, and projecting multiple frames of fringes is not conducive to dynamic 3D measurement.

[0003] Speckle structured light technology (such as Kinect, Intel RealSense D435 / D455) projects a single-frame speckle pattern onto the scene, and calculates the depth of target points using a matching algorithm. Its advantages include low cost and the ability to measure dynamic objects, but its accuracy is limited. Scanning teeth with this method presents a problem: if the speckles are too dense, scattering due to the translucent nature of the tooth surface will blur them, making matching difficult; if the speckles are too sparse, point correspondence will also be difficult. To achieve reliable point correspondence, some methods employ multiple cameras (e.g., three or more).

[0004] 3D scanning technology using laser lines projects single or multiple laser lines onto a scene. The key lies in identifying the number of each laser line. Since each laser line corresponds to a light plane, once the number of a laser line in the camera image is identified, the corresponding light plane equation is determined. Based on the coordinates of the camera center point and a pixel on the laser line in the image, a ray can be determined. The intersection of this ray and the light plane equation determines the 3D coordinates of the target point. The point clouds obtained by this method are usually quite sparse (for example, a single-frame scan can only obtain the point cloud of the area illuminated by a few or a dozen laser lines). To stitch together point clouds from multiple frames, this method usually requires attaching artificial markers to the object's surface. However, attaching markers is inconvenient on the surfaces of some targets, such as teeth in the mouth.

[0005] To achieve point cloud stitching without artificial markers, denser laser lines need to be projected. To identify the laser line numbers, some schemes project laser lines of multiple colors, using the spatial combinations of different colors of adjacent laser lines to encode their numbers. This approach requires capturing images of the laser lines with a color camera, which typically employs a Bayer filter, reducing the camera's sensitivity. For example, when using blue or red laser lines, only 1 / 4 of the pixels in a color camera have a sensitive response, while the other 3 / 4 show almost no response. Similarly, only half of the pixels in a color camera have a sensitive response to green laser lines. Summary of the Invention

[0006] This application provides a three-dimensional scanning system, method, and computer-readable storage medium that eliminates the need to attach external markers to the scanned object, thereby reducing cost and power consumption while ensuring high-precision measurement results.

[0007] In a first aspect, a three-dimensional scanning system is provided, comprising a transmitter, a receiver, and a processor. The transmitter emits a composite line pattern beam toward the object being scanned. The composite line pattern includes a dense line pattern composed of M measurement lines and a sparse line pattern composed of N coding lines, where M and N are positive integers and M is greater than N. Each coding line in the sparse line pattern is aligned with at least a portion of the measurement lines in the dense line pattern to achieve unique coding. The receiver includes a first camera and a second camera. The first camera acquires the composite line pattern beam reflected from the object being scanned and generates a first composite line image, which includes a first dense line image and a first sparse line image. The two cameras are used to acquire composite line pattern beams reflected by the scanned object and generate a second composite line image, which includes a second dense line image and a second sparse line image. The processor is used to decode the first dense line image according to the arrangement number of each coded line in the first sparse line image to identify multiple measurement lines in the first dense line image, and to decode the second dense line image according to the arrangement number of each coded line in the second sparse line image to identify multiple measurement lines in the second dense line image. The processor is also used to perform stereo matching using the identified multiple measurement lines of the first dense line image and the multiple measurement lines of the second dense line image to obtain the depth information of the scanned object.

[0008] Secondly, a three-dimensional scanning method is provided, comprising: emitting a composite line pattern beam towards a scanned object, the composite line pattern comprising a dense line pattern composed of M measurement lines and a sparse line pattern composed of N coding lines, where M and N are positive integers and M is greater than N, and each coding line in the sparse line pattern is aligned with at least a portion of the measurement lines in the dense line pattern to achieve unique coding; acquiring the composite line pattern beam reflected by the scanned object and generating a first composite line image and a second composite line image, the first composite line image comprising a first dense line image and a first sparse line image, and the second composite line image comprising a second dense line image and a second sparse line image; decoding the first dense line image according to the arrangement number of each coding line in the first sparse line image to identify multiple measurement lines in the first dense line image; decoding the second dense line image according to the arrangement number of each coding line in the second sparse line image to identify multiple measurement lines in the second dense line image; and performing stereo matching using the identified multiple measurement lines in the first dense line image and the multiple measurement lines in the second dense line image to obtain depth information of the scanned object.

[0009] Thirdly, an electronic device is provided, including a processor and a memory, wherein the processor and the memory are connected, wherein the memory is used to store program code, and the processor is used to call the program code to execute the method in any possible implementation of the method design of the second aspect above.

[0010] Fourthly, a computer-readable storage medium is provided storing a computer program or instructions for implementing the method in any possible implementation of the method design of the second aspect.

[0011] Fifthly, a computer program product is provided, comprising instructions (or programs) that, when executed by a processor, cause the method in any possible implementation of the method design of the second aspect above to be executed.

[0012] In the technical solution of this application, high-precision three-dimensional scanning information can be obtained using only a few light sources. While ensuring accuracy, it not only reduces costs and power consumption, but also eliminates the need to attach markers to the scanned object, reducing labor costs and increasing the scanning speed, thereby improving the speed of three-dimensional reconstruction. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a three-dimensional scanning system provided in an embodiment of this application.

[0014] Figure 2 This is a schematic diagram of a multi-frequency multi-line pattern provided in an embodiment of this application.

[0015] Figure 3This is a schematic diagram of a line pattern number recognition method provided in an embodiment of this application.

[0016] Figure 4 This is a schematic diagram of a composite line pattern beam provided in an embodiment of this application.

[0017] Figure 5 This is a schematic diagram of the optical system structure of a three-dimensional scanning system provided in an embodiment of this application.

[0018] Figure 6 This is a schematic diagram of the acquisition field of view of a three-dimensional scanning system provided in an embodiment of this application.

[0019] Figure 7 This is a schematic diagram showing the distribution of various structural components of a three-dimensional scanning system provided in an embodiment of this application.

[0020] Figure 8 This is a flowchart illustrating a three-dimensional scanning method provided in an embodiment of this application.

[0021] Figure 9 This is a schematic block diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0022] The technical solutions in this application will now be described with reference to the accompanying drawings.

[0023] In the description of the embodiments in this application, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. In this application, "at least one" means one or more, and "more" means two or more.

[0024] The use of prefixes such as "first" and "second" in this application embodiment is solely for distinguishing different descriptive objects and does not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is found in the claims or the context of the embodiments, and the use of such prefixes should not constitute unnecessary restrictions.

[0025] Figure 1 This is a schematic diagram of the system structure of a three-dimensional scanning system provided in this application.

[0026] like Figure 1As shown, the three-dimensional scanning system 10 includes a transmitter 110, a receiver 120, and a processor (not shown in the figure). The transmitter 110 is used to emit a composite line pattern beam 111 to the object being scanned. The composite line pattern beam 111 includes a dense line pattern 140 composed of M measurement lines and a sparse line pattern 130 composed of N coding lines, where M and N are positive integers and M is greater than N. The multiple measurement lines in the dense line pattern 140 are uniquely encoded by the arrangement number of each coding line in the sparse line pattern 130. That is, each coding line in the sparse line pattern 130 is aligned with at least a portion of the measurement lines in the dense line pattern 140 to achieve unique encoding.

[0027] The receiver 120 may include a left camera 121 and a right camera 122. The left and right cameras of the receiver 120 are used to acquire the composite line pattern beam 111 reflected by the scanned object, generate left and right composite line images, and transmit the generated left and right composite line images to the processor. Both left and right composite line images include dense line images and sparse line images. It should be noted that the left and right cameras in this application include a left camera 121 and a right camera 122. The left camera 121 may also be referred to as the first camera, and the right camera 122 may also be referred to as the second camera. The left and right composite line images include a left composite line image and a right composite line image. The left composite line image may also be referred to as the first composite line image, and the right composite line image may also be referred to as the second composite line image. In this application, the first camera is used to acquire the composite line pattern beam 111 reflected by the scanned object and generate a first composite line image, which includes a first dense line image and a first sparse line image. The second camera is used to acquire the composite line pattern beam 111 reflected by the scanned object and generate a second composite line image, which includes a second dense line image and a second sparse line image.

[0028] The processor is used to decode the dense line image in the left and right composite line images according to the arrangement numbers of each coded line in the sparse line image in the left and right composite line images to identify multiple measurement lines, and to perform stereo matching using the identified measurement lines in the left and right dense line images to obtain the depth information of the scanned object. Specifically, the processor is used to decode the first dense line image according to the arrangement numbers of each coded line in the first sparse line image to identify multiple measurement lines in the first dense line image, and to decode the second dense line image according to the arrangement numbers of each coded line in the second sparse line image to identify multiple measurement lines in the second dense line image; the processor is also used to perform stereo matching using the identified multiple measurement lines in the first dense line image and the multiple measurement lines in the second dense line image to obtain the depth information of the scanned object.

[0029] Furthermore, after obtaining the depth information of the scanned object, the processor can acquire the intrinsic and extrinsic parameters of the transmitter 110 and receiver 120 in the 3D scanning system 10, and combine the intrinsic and extrinsic parameters with the depth information of the scanned object to obtain the point cloud of the scanned object; on the other hand, the processor can also perform 3D reconstruction on the obtained point cloud map of the scanned object to obtain the 3D model of the scanned object.

[0030] In this application, the transmitting end 110 can project multi-line laser images of various frequencies, while the receiving end 120 can capture images of the laser lines using a binocular camera (including the aforementioned left camera 121 and right camera 122). The images acquired by the binocular camera are used to decode the low-frequency laser line numbers, as low-frequency laser lines have fewer beams and are easier to decode. Based on this, the high-frequency laser line numbers are then decoded, thereby obtaining a denser three-dimensional point cloud and a three-dimensional model of the scanned object.

[0031] In some embodiments, such as Figure 1 As shown, the dense line pattern 140 includes multiple measurement lines 141, and the sparse line pattern 130 includes multiple coding lines. Exemplarily, the measurement lines in the dense line pattern 140 and the coding lines in the sparse line pattern 130 can be laser lines, with multiple laser lines parallel to each other. Further, the laser lines projected by the transmitting end 110 include those in a vertical direction or near a vertical direction. It should be noted that, in this embodiment, a vertical laser line is defined as one whose extension direction is perpendicular to the baseline between the transmitting end 110 and the receiving end 120. That is, when the transmitting end 110 emits a horizontal laser line, if it is perpendicular to the baseline between the transmitting end 110 and the receiving end 120, it also falls under the category of a vertical laser line as described in this embodiment.

[0032] At the transmitter 110, a single laser line emitted can form an optical plane (the equation of which needs to be obtained through calibration). The laser line is reflected by the object surface, and an image of the laser line is formed on the imaging plane of the camera at the receiver 120. The three-dimensional coordinates of p can be determined by the intersection of a ray formed from the optical center of the camera, passing through a point (denoted as p) at the center of the laser line in the image, and the optical plane. This is the simplest case with only one laser line.

[0033] However, using a single-line laser for 3D scanning results in only one linear point cloud per frame, which is too inefficient. To improve efficiency, multiple laser lines are needed for scanning. When multiple laser lines are used, multiple light planes are formed in space. A ray originating from a point on a laser line in the camera image will intersect with multiple light planes, resulting in multiple intersection points. To determine the target's position in space, the laser line numbers in the image need to be identified to uniquely determine the light plane corresponding to that laser line.

[0034] The above analysis shows that the key to multi-line laser 3D scanning lies in identifying the laser line numbers in the image. Therefore, encoding the laser line numbers is extremely important.

[0035] The following is combined Figure 2 This explains how to use the coding lines of the sparse line pattern 130 to uniquely encode multiple measurement lines of the dense line pattern 140. Figure 2 This is a schematic diagram of a multi-frequency, multi-line pattern provided in this application. Wherein, Figure 2 (a) is a sparse line pattern 130 projected by transmitter 110 at time t. Figure 2 (b) is a dense line pattern 140 projected by the transmitter 110 at time t+1.

[0036] like Figure 2 As shown in (a), at a certain moment (e.g., time t), a low-frequency multi-line pattern (e.g., sparse line pattern 130) is projected through the transmitter 110. The sparse line pattern 130... Figure 2 The sparse line pattern 130, represented by hollow lines, can include six coded lines. Simultaneously, the left and right cameras of the receiver 120 acquire left and right sparse line images, pair_L, respectively.

[0037] like Figure 2 As shown in (b), at the next moment (e.g., t+1), a high-frequency multi-line pattern (e.g., dense line pattern 140) is projected through the transmitter 110. The dense line pattern 140... Figure 2 The dense line pattern 140, represented by black lines, can include 26 measurement lines. Simultaneously, the left and right cameras of the receiving end 120 acquire left and right dense line images, pair_H.

[0038] In this pattern, the measurement lines in the dense line pattern 140 coincide and are aligned with at least one coding line in the sparse line pattern 130, meaning that the spatial projection positions of each measurement line and its aligned coding line in the dense line pattern 140 are the same. Figure 2 As shown, the first coded line is aligned with the first measurement line, the second coded line is aligned with the sixth measurement line, and so on. Therefore, the unique coding of multiple measurement lines in the dense line pattern 140 can be determined by the arrangement and numbering of the coded lines in the sparse line pattern 130.

[0039] The coded lines in a sparse line image pair_L have lower frequencies, meaning fewer lines, making it easier to number them based on the acquired image. In some examples, if there is only a single line, its number can be determined immediately (only one number) as soon as the line is detected in the sparse line image pair_L. Once the numbering of the low-frequency lines is determined, the numbering of the high-frequency lines between any two low-frequency lines can also be determined. Therefore, the numbering of each coded line in the sparse line image should be determined first, and then the numbering of each measurement line in the dense line image can be determined based on the alignment relationship between the coded lines in the sparse line image and the measurement lines in the dense line image.

[0040] The following is combined Figure 3 This section explains how to identify measurement lines in a dense line image by utilizing the arrangement and numbering of each coded line in a sparse line image. Figure 3 This is a schematic diagram of a line pattern number recognition method provided in this application.

[0041] like Figure 3 As shown, the working principle of this application's scheme is illustrated by projecting a sparse line pattern beam with three coded lines from a transmitter (such as a multi-line pattern projector). When the transmitter projects the sparse line pattern beam onto the object's surface, the three-dimensional point P on the object's surface is located on one of the coded lines. Its projection point in the first sparse line image of the left camera 121 is p, and its projection point in the second sparse line image of the right camera 122 is p′. However, in actual measurement, the transmitter first projects the sparse line pattern beam with three coded lines onto the object's surface and the receiver acquires an image including the three-dimensional point P on the object's surface. Then, based on the coordinate information in the image, the world three-dimensional coordinates of the object's surface point P are estimated in reverse. That is, in the actual measurement process, the world three-dimensional coordinates of the object's surface point P are unknown and can only be calculated by acquiring sparse line images and dense line images from the left camera 121 or the right camera 122.

[0042] Specifically, a ray is formed by connecting any point on each coding line in the first or second sparse line image to the optical center of the left or right camera. The equation of this ray and the equation of the light plane corresponding to the multiple coding lines projected from the transmitter are solved to obtain multiple intersection points. Based on projection constraints, these intersection points are projected back onto the second or first sparse line image to determine the intersection points that fall exactly on the corresponding coding lines in the second or first sparse line image. This allows the matching relationship between the coding lines in the first and second sparse line images to be obtained. Furthermore, the matching relationship between the coding lines in the first and second sparse line images is determined. The alignment relationship is used to obtain the number of each coded line in the first sparse line image and the second sparse line image. Then, based on the alignment relationship between each coded line in the first sparse line image and the second sparse line image and each measurement line in the first dense line image and the second dense line image, the number of the measurement line in the first dense line image and the second dense line image is identified. This completes the decoding process of identifying the measurement line in the dense line image by using the arrangement number of the coded lines in the sparse line image. The measurement lines in the first dense line image and the measurement lines in the second dense line image with the same number are used for stereo matching to obtain the depth information of the object surface, and then the world three-dimensional coordinates of point P on the object surface are obtained.

[0043] Taking the image coordinate p in the sparse line image acquired by the left camera 121 as an example, the ray formed by the line connecting it to the optical center of the left camera forms three intersection points with the three optical planes corresponding to these three coding lines. The coordinates of the intersection points can be solved by the ray equation and the optical plane equation. The optical plane equation formed by the three coding lines is known and can be obtained through pre-calibration.

[0044] Specifically, based on the principle of line laser scanning, a single coded line emitted by the transmitter 110 towards the scanned object can form a light plane. Each light plane corresponds to a light plane equation, and each light plane has a unique number. This light plane equation can be obtained through calibration. The receiver 120 acquires the light beam reflected from the scanned object, forming a sparse line image containing multiple coded lines on the camera's imaging plane. The processor extracts any point on any coded line in the sparse line image and, starting from the optical center of the receiver 120, forms a ray with that point on the coded line. The intersection point is the solution of this ray and the light plane equation.

[0045] Furthermore, the processor can extract the centerline of the coded line in the sparse line image using a centerline extraction algorithm. Starting from the optical center of the receiver 120, a ray is formed with any center point of the coded line. The intersection point of this ray with the optical plane is then used to determine the three-dimensional coordinates of the corresponding center point. Compared to directly calculating the intersection point from any point on the coded line, this application obtains the sub-pixel coordinates of the corresponding center point by calculating the centerline of the coded line, and then solves for the intersection point using the sub-pixel center point, thus improving calculation accuracy.

[0046] As illustrated in the above embodiments, taking the ray formed by any point on a certain coded line in the sparse line image acquired from the left camera 121 and the optical center of the left camera as an example, it will have intersections with multiple optical planes. However, only one of these intersections is a 3D point belonging to the object surface. This real 3D point has a strong constraint: its projection point p′ on the sparse line image of the right camera 122 also falls on a line. According to the geometric constraints, the multiple three-dimensional intersections are projected onto the sparse line image obtained by the right camera 122. If one of the multiple intersections falls exactly on a certain coded line in the sparse line image of the right camera 122, then this coded line and the coded line where point p is located in the sparse line image of the left camera 121 are formed by the same beam of light, thereby determining the matching relationship of each coded line in the sparse line images of the left and right cameras; then, according to the number of the optical plane corresponding to the intersection point, the number of the coded line can be confirmed. It should be noted that, taking any point on a coding line in the sparse line image acquired by the right camera 122 as an example, and connecting it with the optical center of the right camera to form a ray, the intersection point formed by the ray and the optical plane is projected onto the sparse line image acquired by the left camera. The method for confirming the coding line number is similar to the above embodiment, and will not be repeated here.

[0047] Specifically, the formula for projecting the three-dimensional intersection points of space onto the camera plane is: Z c x = K[R|T]X, where Z c R represents the depth distance between the spatial point and the camera, x represents the homogeneous image coordinates, R|T represents the rotation and translation matrix between the camera and the world coordinate system of the scanned object, and K represents the 3×3 camera intrinsic parameters.

[0048] After determining the number of each coded line in the sparse line image, the number of each measurement line in the dense line image is further decoded based on the alignment relationship between the coded lines in the sparse line image and the measurement lines in the dense line image.

[0049] Based on the above encoding and decoding principles, after decoding each measurement line in the dense line images of the left and right cameras, stereo matching calculations can be performed on measurement lines with the same number in the dense line images of the left and right cameras to obtain the depth information of the scanned object. Furthermore, after obtaining the depth information of the scanned object, the processor can also obtain a point cloud map of the scanned object based on the intrinsic and extrinsic parameters of the transmitting and receiving ends and the depth information of the scanned object; in addition, the processor can perform three-dimensional reconstruction on the obtained point cloud map of the scanned object, ultimately obtaining a three-dimensional model of the scanned object.

[0050] The above combination Figures 1 to 3 The system design of the three-dimensional scanning system provided in this application is illustrated by example.

[0051] like Figure 1The 3D scanning system 10 shown includes a transmitter 110, a receiver 120, and a processor; wherein, the transmitter 110 is used to emit a composite line pattern beam 111 towards the object being scanned; the receiver 120 is used to acquire the composite line pattern beam 111 reflected back by the object being scanned to generate left and right composite line images and transmit them to the processor; the processor is used to receive the left and right composite line images and process the left and right composite line images to obtain the depth information of the object being scanned.

[0052] In some embodiments, such as Figure 1 As shown, the transmitting end 110 may include a light source 101 and a pattern modulation element 102. The light source 101 is used to emit a light beam to the pattern modulation element 102. The pattern modulation element 102 modulates the light beam emitted by the light source 101 to obtain a composite line pattern beam 111 including a dense line pattern 140 and a sparse line pattern 130. The sparse multi-line pattern 130 can be regarded as a subset of the dense line pattern 140. That is, the coding lines in the projected sparse multi-line pattern 130 coincide and are aligned with at least a portion of the measurement lines in the dense line pattern 140, so that the measurement lines can be uniquely encoded by the numbering of the coding lines.

[0053] For example, the light source 101 can be a light emitting diode (LED), an edge-emitting laser (EEL), a vertical-cavity surface-emitting laser (VCSEL), or an array of multiple light sources. The light emitted by the light source 101 can be any one or a combination of visible light, infrared light, blue light, green light, or ultraviolet light.

[0054] For example, the pattern modulation element 102 can be a mask or a micro-electro-mechanical system (MEMS) galvanometer.

[0055] In some embodiments, the light source 101 can be a dual-band LED light source, and the pattern modulation element 102 can be a mask, so that dense line patterns and sparse line patterns can be projected through the dual-band LED and the mask.

[0056] For example, a dual-band LED light source can emit a first-band beam and a second-band beam. The photomask includes a substrate with a preset pattern, the preset pattern on the substrate being as follows: Figure 4 As shown, the preset pattern includes a first region (white shaded area) and a second region (black shaded area).

[0057] In one example, the first region allows only the first-band beam to pass through, while the second region allows both the first-band and second-band beams to pass through. That is, when the dual-band LED light source emits a first-band beam that passes through the mask, the first-band beam passes through both the first and second regions on the mask to form a shape like... Figure 2 The dense line pattern shown in (b); when the second-band beam emitted by the dual-band LED light source passes through the mask, the second-band beam can only pass through the second region on the mask to form a pattern as shown in (b). Figure 2 The sparse line pattern shown in (a) can then be used to realize multi-line pattern projection with different densities.

[0058] In another example, the first region only allows the first band beam to pass through, and the second region only allows the second band beam to pass through. That is, the dual-band LED light source can simultaneously project beams of different bands / colors (such as the first band beam and the second band beam), forming composite line patterns after passing through different regions on the mask. The first band beam corresponds to a dense line pattern, and the second band beam corresponds to a sparse line pattern. Then, the receiver 120 acquires a frame of composite line image and obtains dense and sparse line images by identifying different colored line patterns in the composite line image. The first band beam corresponds to the dense line image, and the second band beam corresponds to the sparse line image. Further, each coded line in the sparse line image is first decoded, and then each measurement line in the dense line image is decoded based on the sparse line image to obtain the codes for each coded line and each measurement line.

[0059] For example, Figure 4 The white shaded area of ​​the mask shown can be designed to allow only blue light sources to pass through, and the black shaded area of ​​the mask can be designed to allow only green light sources to pass through. Blue and green light sources simultaneously emit beams to form a multi-line image including sparse green coded lines and dense blue measurement lines. First, a small number of green coded lines are identified based on color. Then, the green coded lines are decoded using the technical solution of this application. Since the blue measurement lines are located between the green coded lines, they can be decoded based on the numbering of the green coded lines.

[0060] For example, the aforementioned dual-band LED light source can be replaced with a laser light source, which may include laser sub-sources of different wavelengths (e.g., a blue laser sub-source and a green laser sub-source). The blue laser sub-source forms a dense line pattern, while the green laser sub-source forms a sparse line pattern. This method can also achieve projection of multi-line patterns with different densities.

[0061] In some examples, the preset pattern on the photomask can be achieved by coating, for example, coating a first region with a transparent film that allows only a first-band beam to pass through, and coating a second region with two films that allow both the first-band beam and the second-band beam to pass through; or, coating a first region with a transparent film that allows only the first-band beam to pass through, and coating a second region with a transparent film that allows only the second-band beam to pass through.

[0062] In some examples, a collimating element may be provided between the light source 101 and the pattern modulation element 102 so that the light beam emitted by the light source 101 forms a parallel light beam after passing through the collimating element. The collimating element may be, for example, a compound eye lens or a collimating lens.

[0063] In some examples, a projection lens may also be provided on the light-emitting surface of the pattern modulation element 102. The projection lens is used to amplify the multi-line pattern beam formed by the pattern modulation element 102 (such as a mask), thereby expanding the projection field of view.

[0064] In other embodiments, the pattern modulation element 102 can be a MEMS galvanometer. If a MEMS galvanometer is used to realize the projection of multi-line patterns of different densities, when the transmitter 110 is an LED light source, a collimating element can be set between the LED light source and the MEMS galvanometer to make the beam emitted by the LED light source a parallel beam. When the parallel beam is a line parallel beam, the frequency of the one-dimensional deflection of the MEMS galvanometer can be controlled to form a two-dimensional dense line pattern and a two-dimensional sparse line pattern to be projected onto the scanned object; when the parallel beam is a point parallel beam, the frequency of the two-dimensional deflection of the MEMS galvanometer can be controlled to first form a line beam with the same one-dimensional deflection frequency, and then form a two-dimensional dense line pattern and a two-dimensional sparse line pattern with a different polarization frequency in another dimension to be projected onto the scanned object.

[0065] It should be understood that the use of MEMS galvanometers is generally paired with high-precision control methods, such as control methods with closed-loop feedback. These control methods are existing technologies and are not limited herein.

[0066] In some embodiments, the receiver 120 includes a left camera 121 and a right camera 122. Both the left camera 121 and the right camera 122 include a black and white image sensor and a filter. The black and white image sensor is used to acquire a composite line pattern beam reflected back from the scanned object and generate a corresponding composite line image, or to acquire a dense line pattern in the composite line pattern beam reflected back from the scanned object and generate a dense line image for transmission to the processor.

[0067] For example, a black and white image sensor can be composed of any one or more of the following: charge-coupled device (CCD), complementary metal oxide semiconductor (CMOS), avalanche diode (AD), and single photon avalanche diode (SPAD).

[0068] A filter is placed on the incident light side of the monochrome image sensor, and can be, for example, a narrowband filter that matches the wavelength of the light source. The filter is used to suppress background light noise in other bands so that only composite line pattern beams or dense line patterns in composite line pattern beams can pass through the filter and be acquired by the monochrome image sensor.

[0069] In some examples, both the left camera 121 and the right camera 122 further include imaging lenses for receiving a composite line-patterned light beam reflected back from the scanned object, allowing the composite line-patterned light beam to propagate to and pass through a filter to image onto a corresponding pixel of the image sensor. Exemplarily, the imaging lens includes a single lens or a lens group consisting of multiple lenses.

[0070] In some embodiments, the receiver 120 may further include a third camera, which includes a color image sensor (or RGB image sensor, texture image sensor, etc.). The color image sensor is used to acquire texture images to achieve texture mapping of the three-dimensional model and obtain a textured three-dimensional model.

[0071] For example, a color image sensor includes an image sensor and a Bayer filter disposed on the light-incident side of the image sensor, used to acquire the texture of the scanned object and transmit the acquired texture to the processor; the processor renders the point cloud map of the scanned object according to the texture of the scanned object to obtain a textured point cloud model, or performs texture mapping on the three-dimensional model of the scanned object to obtain a textured three-dimensional model.

[0072] When the black and white image sensor only acquires the dense line pattern in the composite line pattern beam to generate a dense line image and transmits it to the processor, the light-incident side of the color image sensor can also be provided with a narrow-band filter that matches the wavelength of the light source emitting the sparse line pattern, so that the color image sensor is only used to acquire the sparse line pattern in the composite line pattern beam to generate a sparse line image and transmit it to the processor, so that the processor can identify multiple measurement lines in the dense line image based on the sparse line image.

[0073] Compared to color image sensors, monochrome image sensors have better sensitivity and a higher signal-to-noise ratio in the acquired images. Using monochrome sensors to acquire composite line pattern beams is beneficial for high-precision measurement of the scanned object. In this embodiment, color image sensors are mainly used to acquire sparse line patterns for encoding or the texture of the scanned object, and are not directly used to measure the scanned object, so they do not affect the measurement accuracy.

[0074] In some embodiments, the processor can be a standalone dedicated circuit, such as a system-on-a-chip (SOC) chip comprising memory, a central processing unit (CPU), and a bus, a field-programmable gate array (FPGA) chip, an application-specific integrated circuit (ASIC) chip, etc., or it can include general-purpose processing circuitry. For example, when the 3D scanning system 10 is integrated into an electronic device such as a mobile phone, television, computer, or scanner, the processing circuitry of the electronic device can serve as at least a part of the processor.

[0075] Based on the system design of the three-dimensional scanning system provided in the embodiments of this application, Figure 5 An exemplary optical system architecture for a three-dimensional scanning system is shown.

[0076] Figure 5 This is a schematic diagram of the optical system structure of a three-dimensional scanning system provided in this application. Figure 5 As shown, the optical system 20 may include a transmitter 200 and a receiver. The receiver includes a first camera 300 and a second camera 400 (corresponding to the left and right cameras mentioned above). The transmitter 200 is used to emit a composite line pattern beam including sparse and dense line patterns to the object being scanned 500. The first camera 300 and the second camera 400 are used to acquire the composite line pattern beam reflected back by the object being scanned 500 and generate a composite line image.

[0077] The transmitting end 200 includes a first light source 211, a second light source 212, and a mask 270. The first light source 211 and the second light source 212 are used to emit light beams to the mask 270, respectively. The light beam emitted by the first light source 211, after being modulated by the mask 270, can form a dense line pattern and be projected onto the object being scanned 500. The light beam emitted by the second light source 212, after being modulated by the mask 270, can form a sparse line pattern and be projected onto the object being scanned 500. For example, the light beams emitted by the first light source 211 and the second light source 212, after passing through the mask 270, can form a dense line pattern as shown in the image. Figure 2The dense line pattern shown in (b) and as shown in Figure 2 The sparse line pattern shown in (a).

[0078] For example, different light sources emit beams with different wavelengths. The first light source 211 can be a blue laser light source, used to emit blue light to the mask 270; the second light source 212 can be a green laser light source, used to emit green light to the mask 270. The blue laser light source can form a dense line pattern after being modulated by the mask 270, and the green laser light source can form a sparse line pattern after being modulated by the mask 270.

[0079] In some embodiments, the emitting end 200 further includes a collimating element (or collimating lens) located between the light source and the mask 270. The collimating element may include a first collimating element 221 disposed on the light-emitting side of the first light source 211 and a second collimating element 222 disposed on the light-emitting side of the second light source 212. The first collimating element 221 is located between the first light source 211 and the mask 270, and the second collimating element 222 is located between the second light source 212 and the mask 270. The first collimating element 221 is used to collimate the light beam emitted by the first light source 211 to form a parallel light beam, and the second collimating element 222 is used to collimate the light beam emitted by the second light source 212 to form a parallel light beam. Exemplarily, the first collimating element 221 and / or the second collimating element 222 may be a single lens or a lens group consisting of multiple lenses.

[0080] In some embodiments, the transmitter 200 further includes a beam combiner 230, which combines the parallel beams from the first light source 211 and the second light source 212 into a single parallel beam. The beam combiner 230 is located between the light source and the mask 270. Specifically, the first light source 211 and the second light source 212 (or the first collimating element 221 and the second collimating element 222) are respectively positioned on different incident light sides of the beam combiner 230, and the mask 270 is positioned on the emitting light side of the beam combiner 230. The first light source 211 and the second light source 212 can emit beams of different wavelengths to the beam combiner 230, which combines the two parallel beams of different wavelengths into a single parallel beam and propagates it to the mask 270.

[0081] For example, the beam combining element 230 can be a dichroic mirror, used to transmit the light beam emitted by the first light source 211 to the light homogenizing element 240 and reflect the light beam emitted by the second light source 212 to the light homogenizing element 240.

[0082] In some embodiments, the emitting end 200 further includes a homogenizing element 240, which is located on the light-emitting side of the beam combiner 230. Specifically, the homogenizing element 240 is located between the beam combiner 230 and the mask 270, and is used to homogenize the parallel beams combined by the beam combiner 230 to form parallel beams with balanced light energy. Exemplarily, the homogenizing element 240 can be a compound eye lens or a diffuser.

[0083] In some embodiments, the transmitter 200 further includes a first relay lens 250 and a second relay lens 260. The first relay lens 250 is located between the homogenizing element 240 and the second relay lens 260, and the second relay lens 260 is located between the first relay lens 250 and the mask 270. The first relay lens 250 is used to expand the homogenized parallel beam and project it onto the second relay lens 260. The second relay lens 260 is used to reshape the expanded beam into a parallel beam and project it onto the mask 270.

[0084] In some embodiments, the transmitter 200 further includes a projection lens 280 for amplifying the light beam projected by the mask 270 onto the object being scanned 500. Exemplarily, the projection lens 280 may include a single lens or a combination of multiple lenses, without limitation herein.

[0085] It should be noted that the first light source 211, the second light source 212, the first collimating element 221, the second collimating element 222, the beam combining element 230, and the light homogenizing element 240 can constitute a light-emitting assembly, and the optical axes of this light-emitting assembly are not located on the same horizontal line as the optical axes of the first relay lens 250 and the second relay lens 260. For example... Figure 6 As shown in the right figure, this allows the beam emitted by the transmitter 200 to fall within the field of view of the receiver (including the first camera 300 and the second camera 400 mentioned above), and AA alignment is not required during the module assembly process of the transmitter 200, making installation more convenient.

[0086] At the emitting end 200, a collimating lens is provided on the light-emitting side of both the first light source 211 and the second light source 212 to collimate the light beams emitted by the first light source 211 and the second light source 212 respectively, forming parallel light beams that are transmitted to the beam combiner 230. The beam combiner 230 combines the parallel light beams formed by the first light source 211 and the second light source 212 into a single parallel light beam. After being combined by the beam combiner 230, the parallel light beam is homogenized by the beam homogenizing element 240 to form a parallel light beam with balanced light energy, which propagates towards the first relay lens 250. The first relay lens 250 expands the homogenized parallel light beam and emits it towards the second relay lens 260. The second relay lens 260 reshapes the expanded beam into a parallel light beam and projects it onto the mask 270. The light beams from the first light source 211 and the second light source 212 form parallel light beams after passing through the mask 270. Figure 2 The dense line pattern shown in (b) and as shown in Figure 2 The sparse line pattern shown in (a) is projected onto the scanned object 500 through the magnification effect of the projection lens 280.

[0087] In some examples, both the first camera 300 and the second camera 400 may include a monochrome image sensor, a reflector, and an imaging lens. The light beam reflected back from the scanned object 500 is focused by the imaging lens and then enters the monochrome image sensor of each camera via the reflector, generating sparse line images and dense line images respectively. For example... Figure 5 As shown, the first camera 300 includes a first monochrome image sensor 310, a first reflector 320, and a first imaging lens 330. The first imaging lens 330 is used to focus the light beam reflected back from the scanned object 500, and the first reflector 320 is used to reflect the focused light beam so that the light beam enters the first monochrome image sensor 310. The first monochrome image sensor 310 is used to acquire the light beam to form a first sparse line image and a first dense line image. The second camera 400 includes a second monochrome image sensor 410, a second reflector 420, and a second imaging lens 430. The second imaging lens 430 is used to focus the light beam reflected back from the scanned object 500, and the second reflector 420 is used to reflect the focused light beam so that the light beam enters the second monochrome image sensor 410. The second monochrome image sensor 410 is used to acquire the light beam to form a second sparse line image and a second dense line image.

[0088] For example, the first imaging lens 330 and / or the second imaging lens 430 may include one or more lenses. When the first imaging lens 330 and / or the second imaging lens 430 are multiple lenses, they may be cemented doublet lenses.

[0089] In some examples, such as Figure 6As shown in the left figure, from the baseline direction of the first black and white image sensor 310 and the second black and white image sensor 410, the first black and white image sensor 310 and the second black and white image sensor 410 are not on the same straight line with the optical axis of their respective imaging lenses, but are set at an angle relative to each other. This setting can make the acquisition field of view of the image sensor tilted, so that the acquisition field of view of the first black and white image sensor 310 and the second black and white image sensor 410 overlap, without having to be designed at an angle, and no AA alignment is required during installation, which greatly improves the installation efficiency.

[0090] In some embodiments, such as Figure 5 As shown, the receiving end also includes a third camera 600, which includes a color image sensor 610, a third reflector 620, and a third imaging lens 630. The third imaging lens 630 is used to focus the light beam reflected back from the scanned object 500, and the third reflector 620 is used to reflect the focused light beam so that the light beam enters the color image sensor 610. The color image sensor 610 is used to acquire the texture information of the scanned object 500.

[0091] The spatial arrangement of the first camera 300, the second camera 400, the third camera 600 in the receiver and the transmitter 200 can be referenced. Figure 7 The third camera 600 and the transmitter 200 are located on the same plane (such as the first plane). The first camera 300 and the second camera 400 are symmetrically arranged about the first plane, which is the plane where the transmitter 200 and the third camera 600 are located. The transmitting optical path of the transmitter 200 is relatively longer than the receiving optical path of each receiver. This arrangement can miniaturize the size of the 3D scanner and better conform to the ergonomic design of the oral scanner.

[0092] Combination Figure 5 It is understood that the receiving optical path of the third camera 600 includes: natural light is focused onto the third reflecting mirror 620 by the third imaging lens 630, and then enters the color image sensor 610 for imaging through the total internal reflection of the third reflecting mirror 620. For example, the optical axis of the third imaging lens 630 and the optical axis of the color image sensor 610 are not on the same straight line, which facilitates the overlap of the field of view with other devices. The third imaging lens 630 can be a cemented doublet lens.

[0093] In some examples, considering that the three-dimensional scanning system (three-dimensional scanner) provided in this application can be applied to the field of oral scanning, given the darkness of the oral cavity environment, in order to improve the imaging quality of the color image sensor 610, the third camera 600 can also be equipped with a supplementary light (such as a white LED) to provide supplementary lighting for the scanned object 500.

[0094] In summary, this application provides a 3D scanning system that combines dense and sparse line patterns. It can acquire high-precision 3D scanning information using only a few light sources. While ensuring accuracy, it not only reduces cost and power consumption, but also eliminates the need to attach markers to the scanned object, reducing labor costs and increasing scanning speed, thereby improving the speed of 3D reconstruction.

[0095] The above combination Figures 1 to 7 The 3D scanning system provided in this application is introduced below, and will be discussed in conjunction with... Figure 8 and Figure 9 This application introduces the three-dimensional scanning method and electronic equipment provided.

[0096] Figure 8 This is a flowchart illustrating a three-dimensional scanning method provided in an embodiment of this application. This method 800 can be applied to... Figure 1 In the 3D scanning system 10 shown, the method 800 may include S810 to S850.

[0097] S810 emits a composite line pattern beam toward the object being scanned.

[0098] The composite line pattern beam includes a dense line pattern and a sparse line pattern. Each coded line in the sparse line pattern is aligned with at least a portion of the measurement lines in the dense line pattern to achieve unique coding.

[0099] For example, in combination Figure 1 As shown, the transmitter 110 in the three-dimensional scanning system 10 can emit a composite line pattern beam 111 towards the object being scanned. The composite line pattern beam 111 includes a sparse line pattern 130 and a dense line pattern 140. The measurement lines in the dense line pattern 140 coincide and are aligned with at least one coding line in the sparse line pattern 130. That is, the measurement lines and the coding lines aligned with them in the dense line pattern 140 are projected to the same position in space.

[0100] Combination Figure 2 As shown, the sparse line pattern 130 includes multiple coding lines (6 coding lines), and the dense line pattern 140 includes multiple measurement lines (26 measurement lines). The first coding line is aligned with the first measurement line, and the second coding line is aligned with the sixth measurement line. The coding of the multiple measurement lines between the first coding line and the second coding line can be determined according to the arrangement number of the first coding line and the second coding line, thereby achieving unique coding.

[0101] S820: Acquire the composite line pattern beam reflected by the scanned object and generate a first composite line image and a second composite line image. The first composite line image includes a first dense line image and a first sparse line image, and the second composite line image includes a second dense line image and a second sparse line image.

[0102] For example, in combination Figure 1 As shown, the first camera and the second camera of the receiver 120 can respectively acquire the composite line pattern beam reflected by the scanned object, and generate a first composite line image and a second composite line image accordingly. The first composite line image and the second composite line image respectively include a dense line image and a sparse line image. That is, the first composite line image may include a first dense line image and a first sparse line image, and the second composite line image may include a second dense line image and a second sparse line image.

[0103] S830, the first dense line image is decoded according to the arrangement number of each coded line in the first sparse line image to identify multiple measurement lines in the first dense line image.

[0104] For example, the processor in the 3D scanning system 10 can decode the first dense line image based on the arrangement number of each coded line in the first sparse line image to identify multiple measurement lines in the first dense line image. The encoding and decoding principle can be found in [reference needed]. Figure 3 and Figure 4 The relevant information will not be repeated here.

[0105] S840, the second dense line image is decoded according to the arrangement number of each coded line in the second sparse line image to identify multiple measurement lines in the second dense line image.

[0106] For example, the processor in the 3D scanning system 10 can also decode the second dense line image according to the arrangement number of each coded line in the second sparse line image to identify multiple measurement lines in the second dense line image. The encoding and decoding principle can be found in [reference needed]. Figure 3 and Figure 4 The relevant information will not be repeated here.

[0107] S850 uses multiple measurement lines from the first dense line image and multiple measurement lines from the second dense line image after recognition to perform stereo matching in order to obtain the depth information of the scanned object.

[0108] For example, the processor in the 3D scanning system 10 can perform stereo matching using multiple measurement lines from the identified first dense line image and multiple measurement lines from the second dense line image to obtain depth information of the scanned object.

[0109] In some embodiments, the method 800 may further include: acquiring intrinsic and extrinsic parameters of the transmitter and receiver; and combining the intrinsic and extrinsic parameters with the depth information of the scanned object to obtain a point cloud map of the scanned object.

[0110] In some embodiments, the method 800 may further include: performing three-dimensional reconstruction on the point cloud map of the scanned object to obtain a three-dimensional model of the scanned object.

[0111] The three-dimensional scanning method provided in this application can obtain high-precision three-dimensional scanning information, such as high-precision three-dimensional scanning information of teeth. While ensuring accuracy, it can also reduce costs and power consumption, increase the three-dimensional scanning rate, and thus improve the three-dimensional reconstruction rate.

[0112] Figure 9 This is a schematic block diagram of an electronic device 900 provided in an embodiment of this application. The electronic device 900 includes a memory 910, a processor 920, and a communication interface 930. The memory 910, processor 920, and communication interface 930 are connected via internal connection paths. The memory 910 stores instructions, and the processor 920 executes the instructions stored in the memory 910 to control the communication interface 930 to acquire information, or to enable the electronic device 900 to implement the aforementioned three-dimensional scanning method. Optionally, the memory 910 can be coupled to the processor 920 via an interface, or it can be integrated with the processor 920.

[0113] It should be noted that the communication interface 930 described above uses a transceiver device, such as, but not limited to, a transceiver. The communication interface 930 may also include an input / output interface.

[0114] The memory 910 stores one or more computer programs, which include instructions that, when executed by the processor 920, cause the electronic device 900 to perform the three-dimensional scanning methods described in the above embodiments.

[0115] In implementation, each step of the above method can be completed by the integrated logic circuitry of the hardware in the processor 920 or by instructions in software form. The method disclosed in the embodiments of this application can be directly implemented by the hardware processor, or by a combination of hardware and software modules in the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory 910, and the processor 920 reads the information in memory 910 and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are not provided here.

[0116] In some embodiments, the above-mentioned electronic device 900 may be a mobile phone, television, computer, scanner, or other device, and this application does not limit it.

[0117] This application also provides a computer-readable storage medium storing program code, which, when executed on a computer, causes the computer to perform the above-described actions. Figure 8 The three-dimensional scanning method shown.

[0118] This application also provides a computer program product, which includes a computer program that, when run, causes the computer to perform the above-described actions. Figure 8 The three-dimensional scanning method shown.

[0119] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0120] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0121] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0122] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0123] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0124] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0125] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A three-dimensional scanning system, characterized in that, include: The transmitting end is used to emit a composite line pattern beam toward the scanned object. The composite line pattern beam includes a dense line pattern composed of M measurement lines and a sparse line pattern composed of N coding lines, where M and N are positive integers and M is greater than N. Each coding line in the sparse line pattern is aligned with at least a portion of the measurement lines in the dense line pattern to achieve unique coding. The coding lines and the measurement lines are laser lines. The receiving end includes a first camera and a second camera. The first camera is used to acquire the composite line pattern beam reflected by the scanned object and generate a first composite line image including a first dense line image and a first sparse line image. The second camera is used to acquire the composite line pattern beam reflected by the scanned object and generate a second composite line image including a second dense line image and a second sparse line image. The processor is configured to decode the first dense line image according to the arrangement number of each coded line in the first sparse line image to identify multiple measurement lines in the first dense line image, and to decode the second dense line image according to the arrangement number of each coded line in the second sparse line image to identify multiple measurement lines in the second dense line image; and to perform stereo matching using the identified multiple measurement lines of the first dense line image and the multiple measurement lines of the second dense line image to obtain the depth information of the scanned object.

2. The three-dimensional scanning system according to claim 1, characterized in that, The processor is also used to acquire the intrinsic and extrinsic parameters of the transmitter and receiver, and combine the intrinsic and extrinsic parameters with the depth information of the scanned object to obtain the point cloud or 3D model of the scanned object.

3. The three-dimensional scanning system according to claim 1 or 2, characterized in that, Decoding the first dense line image or the second dense line image based on the arrangement number of each coded line in the first sparse line image or the second dense line image to identify multiple measurement lines in the first dense line image or the second dense line image includes: A ray is formed by connecting any point on each coding line in the first sparse line image or the second sparse line image with the optical center of the first camera or the second camera. The ray equation corresponding to the ray and the optical plane equation corresponding to the multiple coding lines projected by the transmitting end are solved to obtain multiple intersection points. Based on projection constraints, the multiple intersection points are back-projected onto the second sparse line image or the first sparse line image to determine the intersection points that fall exactly on the corresponding coding lines in the second sparse line image or the first sparse line image, thereby obtaining the matching relationship of each coding line in the first sparse line image and the second sparse line image. The number of each coded line in the first sparse line image and the second sparse line image is obtained based on the matching relationship of each coded line in the first sparse line image and the second sparse line image. The number of the measurement line in the first dense line image and the second dense line image is identified based on the alignment relationship between each coded line in the first sparse line image and the second sparse line image and each measurement line in the first dense line image and the second dense line image.

4. The three-dimensional scanning system according to claim 1 or 2, characterized in that, The transmitting end includes a light source and a pattern modulation element. The light source is used to emit a light beam to the pattern modulation element, and the pattern modulation element is used to modulate the light beam emitted by the light source and project the composite line pattern light beam, which includes the dense line pattern and the sparse line pattern, onto the scanned object.

5. The three-dimensional scanning system according to claim 4, characterized in that, The light source includes at least two sub-light sources, which are used to emit light beams to the pattern modulation element respectively. After being modulated by the pattern modulation element, the light beams are projected onto the scanned object with the dense line pattern and the sparse line pattern respectively.

6. The three-dimensional scanning system according to claim 5, characterized in that, The light source is used to emit a first-band beam and a second-band beam; the pattern modulation element is a mask, the mask includes a first region and a second region, the first region allows the first-band beam to pass through, and the second region allows both the first-band beam and the second-band beam to pass through; or, the first region allows the first-band beam to pass through, and the second region allows the second-band beam to pass through.

7. The three-dimensional scanning system according to claim 4, characterized in that, The transmitting end also includes a collimating element, which is disposed between the light source and the pattern modulation element, and is used to collimate the light beam emitted by the light source to form a parallel light beam.

8. The three-dimensional scanning system according to claim 7, characterized in that, The pattern modulation element is a MEMS galvanometer; When the parallel beam is a line parallel beam, the frequency of the one-dimensional deflection of the MEMS galvanometer is controlled to form a two-dimensional dense line pattern and a two-dimensional sparse line pattern, and projected onto the scanned object. When the parallel beam is a point parallel beam, by controlling the frequency of the two-dimensional deflection of the MEMS galvanometer, a line beam is first formed by the same one-dimensional deflection frequency, and then a two-dimensional dense line pattern and a two-dimensional sparse line pattern are formed by the different polarization frequencies in another dimension, and then projected onto the scanned object.

9. The three-dimensional scanning system according to claim 7, characterized in that, The transmitting end also includes a beam combiner, which is disposed between the collimating element and the pattern modulation element, and is used to combine parallel beams of different wavelengths into a single parallel beam.

10. The three-dimensional scanning system according to claim 9, characterized in that, The transmitting end also includes a light homogenizing element, which is disposed between the beam combining element and the pattern modulation element, and is used to homogenize the parallel beam after it has been combined by the beam combining element.

11. The three-dimensional scanning system according to claim 10, characterized in that, The transmitter also includes a first relay lens and a second relay lens, wherein the first relay lens is located between the light-diffusing element and the second relay lens, and the second relay lens is located between the first relay lens and the pattern modulation element; The first relay lens is used to expand the parallel beam after homogenization and project it onto the second relay lens. The second relay lens is used to reshape the expanded beam into a parallel beam and project it onto the pattern modulation element.

12. The three-dimensional scanning system according to claim 11, characterized in that, The optical axes of the first relay lens, the second relay lens, and the light-emitting assembly including the light source, the collimating element, the beam combining element, and the light-uniforming element are not located on the same horizontal line.

13. The three-dimensional scanning system according to any one of claims 5 to 12, characterized in that, The first camera and the second camera include a black and white image sensor, which is used to acquire the composite line pattern beam reflected back by the scanned object and generate a corresponding composite line image.

14. The three-dimensional scanning system according to claim 13, characterized in that, The receiving end also includes a third camera, which includes a color image sensor for acquiring the texture of the scanned object.

15. The three-dimensional scanning system according to claim 14, characterized in that, The first camera, the second camera, and the third camera all include an imaging lens, wherein the image sensor in the first camera, the second camera, and the third camera and the optical axis of the imaging lens are not located on the same straight line.

16. The three-dimensional scanning system according to claim 14, characterized in that, The third camera and the transmitting end are located on the same plane. The first camera and the second camera are symmetrically arranged about a first plane, which is the plane where the transmitting end and the third camera are located. The transmitting optical path of the transmitting end is longer than the receiving optical path of the receiving end.

17. A three-dimensional scanning method, applied to a three-dimensional scanning system including a transmitter and a receiver, characterized in that, include: A composite line pattern beam is emitted toward the scanned object. The composite line pattern beam includes a dense line pattern composed of M measurement lines and a sparse line pattern composed of N coding lines, where M and N are positive integers and M is greater than N. Each coding line in the sparse line pattern is aligned with at least a portion of the measurement lines in the dense line pattern to achieve unique coding. The coding lines and the measurement lines are laser lines. The composite line pattern beam reflected by the scanned object is acquired and a first composite line image and a second composite line image are generated. The first composite line image includes a first dense line image and a first sparse line image, and the second composite line image includes a second dense line image and a second sparse line image. The first dense line image is decoded according to the arrangement number of each coded line in the first sparse line image to identify multiple measurement lines in the first dense line image. The second dense line image is decoded according to the arrangement number of each coded line in the second sparse line image to identify multiple measurement lines in the second dense line image; The depth information of the scanned object is obtained by stereo matching using multiple measurement lines from the first dense line image and the second dense line image after recognition.

18. The three-dimensional scanning method according to claim 17, characterized in that, The method further includes: Obtain the intrinsic and extrinsic parameters of the transmitter and the receiver; By combining the intrinsic and extrinsic parameters and the depth information of the scanned object, a point cloud or 3D model of the scanned object is obtained.

19. The three-dimensional scanning method according to claim 17 or 18, characterized in that, Decoding the first dense line image or the second dense line image based on the arrangement number of each coded line in the first sparse line image or the second dense line image to identify multiple measurement lines in the first dense line image or the second dense line image includes: A ray is formed by connecting any point on each coding line in the first sparse line image or the second sparse line image with the optical center of the first camera or the second camera in the receiver. The ray equation corresponding to the ray and the optical plane equation corresponding to the multiple coding lines projected by the transmitter are solved to obtain multiple intersection points. Based on projection constraints, the multiple intersection points are back-projected onto the second sparse line image or the first sparse line image to determine the intersection points that fall exactly on the corresponding coding lines in the second sparse line image or the first sparse line image, thereby obtaining the matching relationship between each coding line in the first sparse line image and the second sparse line image. The number of each coded line in the first sparse line image and the second sparse line image is obtained based on the matching relationship of each coded line in the first sparse line image and the second sparse line image. The number of the measurement line in the first dense line image and the second dense line image is identified based on the alignment relationship between each coded line in the first sparse line image and the second sparse line image and each measurement line in the first dense line image and the second dense line image.

20. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that is executed by a processor to implement the method as described in any one of claims 17 to 19.

Images