Calibration and measurement method and system based on binocular auxiliary single-objective telecentric structured light system

Abstract

The invention belongs to the technical field of optical system precision detection, and particularly relates to a binocular-assisted single-objective telecentric structured light system calibration and measurement method and system. The method comprises the following steps: obtaining a phase difference value and a height difference value of a reference plane based on a measurement system, fitting a mapping relation between the phase difference value and the height difference value, and realizing calibration from phases to heights of two monocular targets; and converting the phase value of the to-be-measured object into a height value and a point cloud coordinate based on the fitted mapping relation between the phase difference value and the height difference value, and realizing three-dimensional reconstruction and measurement of the to-be-measured object through point cloud splicing. According to the method, the symbol ambiguity problem of a monocular camera lens calibration method is solved, meanwhile, the precision and efficiency problems brought by a traditional projector calibration method are avoided, the phase matching link of an object is avoided, and therefore the problems of matching errors and information loss caused by phase matching under the shielding condition are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of precision detection technology of optical systems, specifically relating to a calibration and measurement method and system for a telecentric structured light system based on binocular-assisted monocular vision. Background Technology

[0002] Structured light measurement technology, with its advantages of non-contact and rapid imaging, is widely used in fields such as industrial inspection and cultural relic preservation. This technology projects a known fringe pattern onto the surface of an object and uses a camera to acquire images of the deformed fringe and phase information. By calibrating the phase-to-height conversion relationship, 3D reconstruction and measurement can be achieved. Telecentric lenses, with their constant magnification and high image quality, have become a key component of structured light systems. However, due to the unique optical characteristics of telecentric lenses, unlike common pinhole lenses, they require a more complex calibration and measurement process.

[0003] Existing research has proposed different calibration methods for accurate calibration, including phase height model calibration and triangulation calibration. Phase height model calibration is simple to operate, but its measurement accuracy is limited by high-precision 3D calibration components or a lifting platform, increasing system hardware costs. Triangulation calibration does not require complex and expensive equipment and is robust. It obtains 3D point coordinates by calibrating the camera and projector separately and then establishing a combined imaging model. However, for telecentric camera calibration, the affine imaging model suffers from sign ambiguity, requiring the introduction of other methods to determine parameter signs. For projector calibration, a large number of horizontal and vertical stripe images need to be projected, reducing calibration efficiency. Furthermore, projectors suffer from gamma distortion and lens distortion, which differ from camera distortion; directly using camera distortion correction methods cannot accurately describe the projector's optical characteristics. Although binocular structured light systems can overcome the sign ambiguity problem of telecentric structured light and eliminate the need for projector calibration, the binocular imaging model relies on phase matching between the two eyes. When there are height variations in the object, occlusion blind spots can occur, leading to binocular matching errors and affecting 3D reconstruction and measurement.

[0004] In summary, while telecentric structured light measurement technology has applications in fields such as 3D reconstruction measurement and surface topography analysis, challenges remain in its application. These challenges include ambiguous sign interpretations in telecentric lens camera calibration, errors and efficiency issues in projector calibration, and occlusion effects within the system. Therefore, proposing practical and effective solutions to these technical difficulties is crucial for promoting the practical application and performance improvement of telecentric structured light measurement technology. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a calibration and measurement method and system for a telecentric structured light system based on binocular-assisted monocular vision, aiming to solve the binocular matching error problem caused by occlusion in the prior art and achieve accurate measurement of telecentric structured light.

[0006] To achieve the above objectives, the present invention provides the following solution: A calibration and measurement method for a telecentric structured light system based on binocular-assisted monocular vision, the method comprising: The phase difference and height difference of the reference plane are obtained based on the measurement system, and the mapping relationship between the phase difference and height difference is fitted to achieve the calibration of two monocular phase to height. Based on the mapping relationship between the fitted phase difference and height difference, the phase value of the object to be measured is converted into the height value and point cloud coordinates. The three-dimensional reconstruction and measurement of the object to be measured are achieved by stitching the point cloud.

[0007] Preferably, the measurement system includes: Support mechanism, left camera, left lens, projector, right camera, right lens, object to be measured, tray and displacement mechanism.

[0008] Preferably, the method for calibrating the phase-to-height relationship between two monocular phase sensors by obtaining the phase difference and height difference values ​​of a reference plane based on a preset measurement system and fitting the mapping relationship between the phase difference and height difference values ​​includes: A measurement system was built, and a binocular imaging model was constructed based on the measurement system. A blank image was projected onto the calibration board through the binocular imaging model to obtain the parameters of the binocular imaging model. Replace the calibration board with a flat white board, project the stripe image onto the flat white board, and move the flat white board to different height positions to obtain reference planes at different heights, wherein the reference plane at the initial position is used as the reference plane; The left and right cameras respectively acquire stripe images, obtain the phase of the reference plane in the left and right cameras, and subtract the phase of the reference plane from the phase of the reference plane at different heights in the left and right cameras to obtain the phase difference value between the left and right cameras. Based on the parameters of the binocular imaging model and the phase of the reference plane, the height value of the reference plane is obtained. The height difference is obtained by subtracting the height value of the reference plane from the height value of the reference plane at different heights. By using a polynomial model to fit the mapping relationship between the phase difference and the height difference between the reference planes in the left and right cameras respectively, the phase-to-height calibration of the two monocular cameras can be completed.

[0009] Preferably, a method for calibrating the phase-to-height coordinates of two monocular cameras can be achieved by using a polynomial model to fit the mapping relationship between the phase difference and height difference between the reference planes in the left and right cameras, respectively. ; ; in, For the first i pixel coordinates For the firsti The height difference corresponding to each pixel and These are the polynomial fitting coefficients for the left and right cameras, respectively. This represents the phase difference value in the left camera. This represents the phase difference value in the right camera. d Let the degree be the polynomial. , D The total degree of the polynomial.

[0010] Preferably, a method for converting the phase value of the object to be measured into a height value and point cloud coordinates based on the fitted mapping relationship between the phase difference and the height difference, and then realizing the three-dimensional reconstruction and measurement of the object to be measured through point cloud stitching includes: A fringe image is projected onto the object to be measured, and the fringe image is modulated by the height of the object. The left and right cameras respectively acquire stripe images of the object to be measured, and obtain the phase difference value of the object in the left and right cameras; By fitting the mapping relationship between the phase difference and the height difference, the phase of the object to be measured in the left and right cameras is converted into the height value, and the point cloud coordinates in the left and right cameras are obtained based on the height value; By stitching and fusing point cloud coordinates, the three-dimensional reconstruction and measurement of the object under test can be achieved.

[0011] The present invention also provides a calibration and measurement system for a telecentric structured light system based on binocular-assisted monocular vision. The system is used to implement the aforementioned method and includes a calibration module and a measurement module. The calibration module is used to obtain the phase difference and height difference values ​​of the reference plane based on the measurement system, fit the mapping relationship between the phase difference and height difference values, and realize the calibration of the two monocular phase to height. The measurement module is used to convert the phase value of the object to be measured into the height value and point cloud coordinates based on the mapping relationship between the fitted phase difference and height difference. The three-dimensional reconstruction and measurement of the object to be measured are achieved by stitching the point cloud.

[0012] Preferably, the measurement system includes: Support mechanism, left camera, left lens, projector, right camera, right lens, object to be measured, tray and displacement mechanism.

[0013] Preferably, the calibration module includes: a parameter acquisition unit, a plane acquisition unit, a first difference unit, a second difference unit, and a fitting unit; The parameter acquisition unit is used to build a measurement system and construct a binocular imaging model based on the measurement system. It then projects a blank image onto the calibration board through the binocular imaging model to obtain the parameters of the binocular imaging model. The plane acquisition unit is used to replace the calibration board with a flat white board, project a stripe image onto the flat white board, and move the flat white board to different height positions to obtain reference planes at different heights, wherein the reference plane at the initial position is used as the reference plane; The first difference unit is used to acquire stripe images by the left and right cameras respectively, obtain the phase of the reference plane in the left and right cameras, and subtract the phase of the reference plane at different heights in the left and right cameras from the phase of the reference plane to obtain the phase difference value between the left and right cameras. The second difference unit is used to obtain the height value of the reference plane based on the parameters of the binocular imaging model and the phase of the reference plane, and to obtain the height difference value by subtracting the height value of the reference plane from the height value of the reference plane at different heights. The fitting unit is used to fit the mapping relationship between the phase difference and the height difference of the reference plane in the left and right cameras using a polynomial model, thereby completing the phase-to-height calibration of the two monocular cameras.

[0014] Preferably, the fitting unit uses a polynomial model to fit the mapping relationship between the phase difference and height difference between the reference planes in the left and right cameras, respectively, thus completing the phase-to-height calibration of the two monocular cameras. This method includes: ; ; in, For the first i pixel coordinates For the first i The height difference corresponding to each pixel and These are the polynomial fitting coefficients for the left and right cameras, respectively. This represents the phase difference value in the left camera. This represents the phase difference value in the right camera. d Let the degree be the polynomial. , D The total degree of the polynomial.

[0015] Preferably, the measurement module includes: a projection unit, a third difference unit, a conversion unit, and a reconstructed measurement unit; The projection unit is used to project a stripe image onto the object to be measured, and modulate the stripe image by the height of the object; The third difference unit is used to acquire stripe images of the object to be measured by the left and right cameras respectively, and to obtain the phase difference value of the object to be measured in the left and right cameras; The conversion unit is used to convert the phase of the object to be measured in the left and right cameras into height values ​​by fitting the mapping relationship between the phase difference and the height difference, and to obtain the point cloud coordinates in the left and right cameras based on the height values; The reconstruction measurement unit is used to stitch and fuse point cloud coordinates to achieve three-dimensional reconstruction and measurement of the object under test.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention utilizes a binocular method to obtain high-precision height information of a planar whiteboard to establish a pixel-level phase-height mapping relationship. This overcomes the symbol ambiguity problem of monocular camera lens calibration methods and avoids the accuracy and efficiency issues associated with traditional projector calibration methods. Using this mapping relationship, phase values ​​are converted into height information and 3D point cloud coordinates. Based on a matching and stitching method, the point clouds from the left and right cameras are fused to achieve complete 3D reconstruction. This avoids the phase matching step of objects and effectively solves the matching error and information loss problems caused by occlusion. Attached Figure Description

[0017] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the measurement system according to an embodiment of the present invention; Figure 2 These are phase diagrams of reference planes at different heights in the left camera according to an embodiment of the present invention; Figure 3 This is a phase diagram of reference planes at different heights in the right camera according to an embodiment of the present invention; Figure 4 This is a schematic diagram showing the position of the reference plane at different heights in an embodiment of the present invention; Figure 5 This is a point cloud image of an object in the left camera according to an embodiment of the present invention; Figure 6 This is a point cloud image of an object in the right camera according to an embodiment of the present invention; Figure 7 This is a complete 3D reconstructed point cloud diagram of an embodiment of the present invention; In the diagram: 1. Support mechanism; 2. Left camera; 3. Left lens; 4. Projector; 5. Right camera; 6. Right lens; 7. Object to be measured; 8. Tray; 9. Displacement mechanism. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Example 1 This invention provides a calibration and measurement method for a telecentric structured light system based on binocular-assisted monocular vision, comprising: The phase difference and height difference of the reference plane are obtained based on the measurement system, and the mapping relationship between the phase difference and height difference is fitted to achieve the calibration of two monocular phase to height. Based on the mapping relationship between the fitted phase difference and height difference, the phase value of the object to be measured is converted into the height value and point cloud coordinates. The three-dimensional reconstruction and measurement of the object to be measured are achieved by stitching the point cloud.

[0022] The specific implementation process of this invention is as follows: A schematic diagram of the measurement system of the present invention is shown below. Figure 1 As shown, the measurement system includes: a support mechanism 1, a left camera 2, a left lens 3, a projector 4, a right camera 5, a right lens 6, an object to be measured 7, a tray 8, and a displacement mechanism 9. The left camera 2, projector 4, and right camera 5 are fixed to the support mechanism 1, and the left lens 3 and right lens 6 are coordinated with the left camera 2 and right camera 5. The object to be measured 7 is placed in the tray 8, and the height of the object to be measured 7 in the tray 8 is controlled by the displacement mechanism 9.

[0023] Furthermore, based on a pre-set measurement system, the phase difference and height difference values ​​of the reference plane are obtained. The mapping relationship between the phase difference and height difference is fitted to achieve the calibration of two monocular phase-to-height measurements. This method includes: A measurement system is built, and a binocular imaging model is constructed based on the measurement system. The binocular imaging model includes: the transformation relationship between the camera pixel coordinates in the left camera 2 and the right camera 5 and the point cloud coordinates in the actual world coordinate system; the calibration board is placed in the tray 8, and under the condition that the projector 4 projects a blank image onto the calibration board, the pixel coordinates of the feature points of the calibration board in the left and right cameras and their corresponding known world coordinates are extracted, and the dual-camera coordinate transformation relationship containing the projection matrix in the binocular imaging model is solved and determined.

[0024] The calibration board is replaced with a flat white board, that is, the flat white board is placed in the tray 8, and the stripe image is projected onto the flat white board using the projector 4. The flat white board is moved to different height positions in the vertical direction using the displacement mechanism 9 to obtain reference planes at different heights, wherein the reference plane at the initial position is used as the reference plane. Left camera 2 and right camera 5 respectively acquire multiple stripe images projected onto a reference plane by projector 4. These stripe images are structured light stripe images with a preset spatial period. For each stripe image sequence acquired from each camera's viewpoint, phase calculation is performed according to the following steps: First, based on the grayscale variation relationship of the same pixel in multiple stripe images, a phase calculation algorithm is used to calculate the wrapping phase value corresponding to that pixel. The wrapping phase value represents the phase information of that pixel within one stripe period. Second, the wrapping phase is subjected to phase unwrapping processing to eliminate periodic phase jumps, obtaining a continuously varying phase distribution within the camera's field of view, thereby obtaining the phase map of the reference plane under the corresponding camera's viewpoint. Through the above stripe image calculation process, the phase distribution of the reference plane in left camera 2 and right camera 5 is obtained respectively. The phase difference between the reference plane at different heights in left camera 2 and right camera 5 and the phase of the reference plane is calculated to obtain the phase difference value of the reference plane in left camera 2 and right camera 5, such as... Figure 2 and Figure 3 As shown, the phase difference values ​​of the reference plane in the left camera 2 and the right camera 5 are respectively expressed as: in, For the first i Each pixel coordinate. For the first n The phase value of the reference plane at a certain height in the left camera 2. The phase value of the reference plane in left camera 2, This represents the phase difference value in the left camera 2. For the first n The phase value of the reference plane at a certain height in the right camera 5. The phase value of the reference plane in right camera 5, This refers to the phase difference value in the right camera 5. i The index variable represents the pixel. n Index variables representing reference planes at different heights.

[0025] After obtaining the phase distribution of the reference plane in the left camera 2 and the right camera 5, in order to establish the phase relationship corresponding to the same spatial point in the left and right cameras and to facilitate the subsequent calculation of the plane height, it is necessary to match the phase of the left and right reference planes. The specific process is as follows: First, the intrinsic and extrinsic parameters in the binocular imaging model are used to perform stereo correction on the left camera 2 and the right camera 5, so that the images of the left and right cameras are in a coplanar imaging state, and the corresponding points of the same spatial point in the left and right images are located at the same epipolar position; then, in the corrected left and right phase maps, based on the epipolar constraint, the pixel pairs with the same phase value are searched on the same epipolar line to determine the pixel position in the left and right cameras corresponding to the same reference plane point, thereby realizing the phase matching of the left and right reference planes.

[0026] After phase matching is completed, the actual spatial position of the reference plane can be calculated by combining the matched left and right camera pixels with the projection matrix parameters of the stereo system, as shown in the following formula: in, For the pixels of left camera 2, For the pixels of camera 5 on the right, These are the parameters in the projection matrix of the left camera 2. For parameters in the projection matrix of the right camera 5, index variables a =1,2, b =1,2,3,4. The actual spatial coordinates of the reference plane, where z The height value is the reference plane.

[0027] This spatial location includes the height value of the reference plane, such as Figure 4 As shown. The height difference is obtained by subtracting the height values ​​of the reference plane from the height values ​​of the reference plane at different heights: in, The height values ​​are for reference planes at different heights. The height value of the reference plane. This represents the height difference corresponding to each pixel.

[0028] By using a polynomial model to fit the mapping relationship between the phase difference and height difference of the reference planes in left camera 2 and right camera 5, the phase-to-height calibration of the two monocular cameras can be completed. The polynomial model is expressed as: ; ; in, and These are the polynomial fitting coefficients for left camera 2 and right camera 5, respectively. dLet the degree be the polynomial. , D The total degree of the polynomial.

[0029] The height is calculated jointly by the left and right pixels. There is no need to distinguish between left and right.

[0030] Furthermore, based on the fitted mapping relationship between phase difference and height difference, the phase value of the object to be measured is converted into height value and point cloud coordinates. The method for achieving 3D reconstruction and measurement of the object through point cloud stitching includes: To measure the object 7, a fringe image is first projected onto it using a projector 4. The height of the object 7 is then used to modulate the fringe image. This modulation converts changes in the height of the object's surface into phase changes in the fringe image, thus encoding the object's three-dimensional height information into the fringe image.

[0031] Left camera 2 and right camera 5 respectively acquire stripe images of the object to be measured. The phase value of the object to be measured 7 can be obtained by solving the stripe images using the phase solution method. Then, the phase difference value of the object to be measured 7 in left camera 2 and right camera 5 can be obtained, which facilitates the fitting of height and eliminates the inherent phase deviation caused by system ambient light interference.

[0032] By using the mapping relationship between the phase difference and height difference values ​​fitted during the calibration process and the phase difference value of the object to be measured 7, the phase of the object to be measured 7 in the left camera 2 and right camera 5 is converted into the actual height value of the object to be measured 7 in the left camera 2 and right camera 5, respectively, as follows: in, and These are the actual height values ​​of the point clouds in left camera 2 and right camera 5, respectively.

[0033] By combining the two-dimensional coordinates determined by the two targets, the three-dimensional point clouds of the left and right cameras can be obtained, as shown below. Figure 5 and Figure 6 As shown.

[0034] Finally, using the 3D point clouds from the left camera 2 and the right camera 5, point cloud feature information with stable geometric characteristics is extracted from the overlapping area of ​​the left and right point clouds. A correspondence between the left and right point clouds is established based on this feature information, and the spatial transformation relationship between the left and right point clouds is calculated by matching the corresponding point pairs. This spatial transformation relationship allows for the fusion of the left and right 3D point clouds, thereby achieving complete reconstruction and measurement of the 3D point clouds and avoiding the binocular matching error problem caused by occlusion effects. Figure 7 As shown.

[0035] In summary, this invention obtains the reference plane height value by solving the binocular imaging model parameters and using a flat whiteboard without occlusion effects for 3D reconstruction. Based on this reference plane height value, the pixel-by-pixel mapping relationship between the phase and height of the reference planes of the two monocular cameras is fitted to complete the calibration of the two monocular cameras. This leverages the high precision advantage of binocular imaging, overcomes the ambiguity of monocular symbols, and eliminates the need for projector calibration, thus avoiding its error and efficiency issues. For the measurement of the device under test, its phase value in each monocular camera is calculated, and the height and point cloud are calculated through the mapping relationship. The point clouds from the two monocular cameras are then stitched together to achieve a complete 3D reconstruction, thereby overcoming the binocular matching error problem caused by occlusion. This method can simultaneously and effectively solve the aforementioned problems existing in telecentric structured light measurement technology.

[0036] The binocular-assisted calibration method proposed in this invention overcomes the symbol ambiguity problem in monocular camera lens calibration by using a phase-to-height mapping method, effectively reducing the number of images in monocular projector calibration and improving calibration efficiency. Simultaneously, it leverages the advantages of the binocular imaging model to improve measurement accuracy. Furthermore, the simultaneous measurement of two monocular cameras and the point cloud fusion method after binocular-assisted calibration avoid phase matching, solving the matching errors and information loss problems caused by occlusion in binocular measurements.

[0037] Example 2 Based on the same inventive concept, the present invention also provides a calibration and measurement system for a telecentric structured light system based on binocular-assisted monocular vision, for implementing the method described in the foregoing embodiments. The system includes a calibration module and a measurement module. The calibration module is used to obtain the phase difference and height difference values ​​of the reference plane based on the measurement system, fit the mapping relationship between the phase difference and height difference values, and realize the calibration of the two monocular phase to height. The measurement module is used to convert the phase value of the object to be measured into the height value and point cloud coordinates based on the mapping relationship between the fitted phase difference and height difference. The three-dimensional reconstruction and measurement of the object to be measured are achieved by stitching the point cloud.

[0038] Furthermore, the measurement system includes: Support mechanism, left camera, left lens, projector, right camera, right lens, object to be measured, tray and displacement mechanism.

[0039] Furthermore, the calibration module includes: a parameter acquisition unit, a plane acquisition unit, a first difference unit, a second difference unit, and a fitting unit; The parameter acquisition unit is used to build a measurement system and construct a binocular imaging model based on the measurement system. It then projects a blank image onto the calibration board through the binocular imaging model to obtain the parameters of the binocular imaging model. The plane acquisition unit is used to replace the calibration board with a flat white board, project a stripe image onto the flat white board, and move the flat white board to different height positions to obtain reference planes at different heights, wherein the reference plane at the initial position is used as the reference plane; The first difference unit is used to acquire stripe images by the left and right cameras respectively, obtain the phase of the reference plane in the left and right cameras, and subtract the phase of the reference plane at different heights in the left and right cameras from the phase of the reference plane to obtain the phase difference value between the left and right cameras. The second difference unit is used to obtain the height value of the reference plane based on the parameters of the binocular imaging model and the phase of the reference plane, and to obtain the height difference value by subtracting the height value of the reference plane from the height value of the reference plane at different heights. The fitting unit is used to fit the mapping relationship between the phase difference and the height difference of the reference plane in the left and right cameras using a polynomial model, thereby completing the phase-to-height calibration of the two monocular cameras.

[0040] Furthermore, the fitting unit uses a polynomial model to fit the mapping relationship between the phase difference and height difference between the reference planes in the left and right cameras, respectively. This allows for the completion of the phase-to-height calibration method for the two monocular cameras. ; ; in, For the first i pixel coordinates For the first i The height difference corresponding to each pixel and These are the polynomial fitting coefficients for the left and right cameras, respectively. This represents the phase difference value in the left camera. This represents the phase difference value in the right camera. d Let the degree be the polynomial. , D The total degree of the polynomial.

[0041] Furthermore, the measurement module includes: a projection unit, a third difference unit, a conversion unit, and a reconstructed measurement unit; The projection unit is used to project a stripe image onto the object to be measured, and modulate the stripe image by the height of the object; The third difference unit is used to acquire stripe images of the object to be measured by the left and right cameras respectively, and to obtain the phase difference value of the object to be measured in the left and right cameras; The conversion unit is used to convert the phase of the object to be measured in the left and right cameras into height values ​​by fitting the mapping relationship between the phase difference and the height difference, and to obtain the point cloud coordinates in the left and right cameras based on the height values; The reconstruction measurement unit is used to stitch and fuse point cloud coordinates to achieve three-dimensional reconstruction and measurement of the object under test.

[0042] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A calibration and measurement method for a telecentric structured light system based on binocular-assisted monocular vision, characterized in that, The method includes: The phase difference and height difference of the reference plane are obtained based on the measurement system, and the mapping relationship between the phase difference and height difference is fitted to achieve the calibration of two monocular phase to height. Based on the mapping relationship between the fitted phase difference and height difference, the phase value of the object to be measured is converted into the height value and point cloud coordinates. The three-dimensional reconstruction and measurement of the object to be measured are achieved by stitching the point cloud.

2. The method according to claim 1, characterized in that, The measurement system includes: Support mechanism, left camera, left lens, projector, right camera, right lens, object to be measured, tray and displacement mechanism.

3. The method according to claim 2, characterized in that, The method for calibrating two monocular phase-to-height measurements by obtaining the phase and height differences of a reference plane based on a pre-defined measurement system and fitting the mapping relationship between the phase and height differences includes: A measurement system was built, and a binocular imaging model was constructed based on the measurement system. A blank image was projected onto the calibration board through the binocular imaging model to obtain the parameters of the binocular imaging model. Replace the calibration board with a flat white board, project the stripe image onto the flat white board, and move the flat white board to different height positions to obtain reference planes at different heights, wherein the reference plane at the initial position is used as the reference plane; The left and right cameras respectively acquire stripe images, obtain the phase of the reference plane in the left and right cameras, and subtract the phase of the reference plane from the phase of the reference plane at different heights in the left and right cameras to obtain the phase difference value between the left and right cameras. Based on the parameters of the binocular imaging model and the phase of the reference plane, the height value of the reference plane is obtained. The height difference is obtained by subtracting the height value of the reference plane from the height value of the reference plane at different heights. By using a polynomial model to fit the mapping relationship between the phase difference and the height difference between the reference planes in the left and right cameras respectively, the phase-to-height calibration of the two monocular cameras can be completed.

4. The method according to claim 3, characterized in that, The method for calibrating the phase-to-height relationship between two monocular cameras can be achieved by using a polynomial model to fit the mapping relationship between the phase difference and height difference between the reference planes in the left and right cameras, respectively. ； ； in, For the first i pixel coordinates For the first i The height difference corresponding to each pixel and These are the polynomial fitting coefficients for the left and right cameras, respectively. This represents the phase difference value in the left camera. This represents the phase difference value in the right camera. d Let the degree be the polynomial. , D The total degree of the polynomial.

5. The method according to claim 4, characterized in that, Based on the mapping relationship between fitted phase difference and height difference, the phase value of the object to be measured is converted into height value and point cloud coordinates. The method of realizing the three-dimensional reconstruction and measurement of the object to be measured by point cloud stitching includes: A fringe image is projected onto the object to be measured, and the fringe image is modulated by the height of the object. The left and right cameras respectively acquire stripe images of the object to be measured, and obtain the phase difference value of the object in the left and right cameras; By fitting the mapping relationship between the phase difference and the height difference, the phase of the object to be measured in the left and right cameras is converted into the height value, and the point cloud coordinates in the left and right cameras are obtained based on the height value; By stitching and fusing point cloud coordinates, the three-dimensional reconstruction and measurement of the object under test can be achieved.

6. A calibration and measurement system for a telecentric structured light system based on binocular-assisted monocular vision, the system being used to implement the method described in any one of claims 1-5, characterized in that, The system includes: a calibration module and a measurement module; The calibration module is used to obtain the phase difference and height difference values ​​of the reference plane based on the measurement system, fit the mapping relationship between the phase difference and height difference values, and realize the calibration of the two monocular phase to height. The measurement module is used to convert the phase value of the object to be measured into the height value and point cloud coordinates based on the mapping relationship between the fitted phase difference and height difference. The three-dimensional reconstruction and measurement of the object to be measured are achieved by stitching the point cloud.

7. The system according to claim 6, characterized in that, The measurement system includes: Support mechanism, left camera, left lens, projector, right camera, right lens, object to be measured, tray and displacement mechanism.

8. The system according to claim 7, characterized in that, The calibration module includes: a parameter acquisition unit, a plane acquisition unit, a first difference unit, a second difference unit, and a fitting unit; The parameter acquisition unit is used to build a measurement system and construct a binocular imaging model based on the measurement system. It then projects a blank image onto the calibration board through the binocular imaging model to obtain the parameters of the binocular imaging model. The plane acquisition unit is used to replace the calibration board with a flat white board, project a stripe image onto the flat white board, and move the flat white board to different height positions to obtain reference planes at different heights, wherein the reference plane at the initial position is used as the reference plane; The first difference unit is used to acquire stripe images by the left and right cameras respectively, obtain the phase of the reference plane in the left and right cameras, and subtract the phase of the reference plane at different heights in the left and right cameras from the phase of the reference plane to obtain the phase difference value between the left and right cameras. The second difference unit is used to obtain the height value of the reference plane based on the parameters of the binocular imaging model and the phase of the reference plane, and to obtain the height difference value by subtracting the height value of the reference plane from the height value of the reference plane at different heights. The fitting unit is used to fit the mapping relationship between the phase difference and the height difference of the reference plane in the left and right cameras using a polynomial model, thereby completing the phase-to-height calibration of the two monocular cameras.

9. The system according to claim 8, characterized in that, The fitting unit uses a polynomial model to fit the mapping relationship between the phase difference and height difference of the reference plane in the left and right cameras, respectively. This allows for the calibration of the phase-to-height relationship between the two monocular cameras. The methods include: ； ； in, For the first i pixel coordinates For the first i The height difference corresponding to each pixel and These are the polynomial fitting coefficients for the left and right cameras, respectively. This represents the phase difference value in the left camera. This represents the phase difference value in the right camera. d Let the degree be the polynomial. , D The total degree of the polynomial.

10. The system according to claim 9, characterized in that, The measurement module includes: a projection unit, a third difference unit, a conversion unit, and a reconstructed measurement unit; The projection unit is used to project a stripe image onto the object to be measured, and modulate the stripe image by the height of the object; The third difference unit is used to acquire stripe images of the object to be measured by the left and right cameras respectively, and to obtain the phase difference value of the object to be measured in the left and right cameras; The conversion unit is used to convert the phase of the object to be measured in the left and right cameras into height values ​​by fitting the mapping relationship between the phase difference and the height difference, and to obtain the point cloud coordinates in the left and right cameras based on the height values; The reconstruction measurement unit is used to stitch and fuse point cloud coordinates to achieve three-dimensional reconstruction and measurement of the object under test.

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