CN116977444A - Stereoscopic microscope calibration method, device and system based on coplanar points - Google Patents
Stereoscopic microscope calibration method, device and system based on coplanar points Download PDFInfo
- Publication number
- CN116977444A CN116977444A CN202310935422.7A CN202310935422A CN116977444A CN 116977444 A CN116977444 A CN 116977444A CN 202310935422 A CN202310935422 A CN 202310935422A CN 116977444 A CN116977444 A CN 116977444A
- Authority
- CN
- China
- Prior art keywords
- calibration
- ccd camera
- stereoscopic microscope
- matrix
- formula
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims abstract description 115
- 239000011159 matrix material Substances 0.000 claims abstract description 107
- 238000013519 translation Methods 0.000 claims abstract description 17
- 238000005457 optimization Methods 0.000 claims description 25
- 238000006073 displacement reaction Methods 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 238000010606 normalization Methods 0.000 claims description 5
- 238000012545 processing Methods 0.000 claims description 4
- 238000007476 Maximum Likelihood Methods 0.000 claims description 3
- 230000003321 amplification Effects 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 238000005286 illumination Methods 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 230000009466 transformation Effects 0.000 claims description 3
- 238000000844 transformation Methods 0.000 claims description 3
- 238000005259 measurement Methods 0.000 abstract description 5
- 238000003384 imaging method Methods 0.000 description 5
- 230000003287 optical effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000001575 pathological effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000036039 immunity Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/80—Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
Landscapes
- Engineering & Computer Science (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Microscoopes, Condenser (AREA)
Abstract
The invention relates to the technical field of computer vision measurement, in particular to a stereoscopic microscope calibration method based on coplanar points, which is used for calibrating a stereoscopic microscope through a calibration plate, wherein the stereoscopic microscope comprises a CCD camera, and the calibration method comprises the following steps: firstly, obtaining a primary point coordinate initial value of a camera by using a zoom ratio method; then, calibrating the scale factors of the camera by adopting an improved camera calibration method based on coplanar points; then calibrating a translation matrix and a rotation matrix of the camera by adopting a calibration method based on coplanar points; and finally, comprehensively considering a distortion model of tangential distortion and radial distortion, and optimizing a parameter initial value by adopting a light beam adjustment method based on an LM algorithm to finally obtain the high-precision camera internal and external parameters. The stereoscopic microscope calibration method based on the coplanar points can finish the calibration of the stereoscopic microscope and improve the calibration precision of the stereoscopic microscope.
Description
Technical Field
The invention relates to the technical field of computer vision measurement, in particular to a stereoscopic microscope calibration method, device and system based on coplanar points.
Background
In the field of computer vision measurement, camera calibration is an indispensable step of acquiring spatial information from image information, specifically a process of determining internal parameters, distortion parameters and external parameters of a camera according to the acquired image information. The calibration of camera parameters is very critical, and the accuracy of the calibration result directly influences the accuracy of the subsequent image measurement result.
Currently, there are many relatively sophisticated macroscopic calibration methods, such as matlab and Opencv self-contained calibration toolboxes. However, the macroscopic calibration method cannot be directly used due to the smaller depth of field and field of view of the stereoscopic microscope. The calibration research on the stereoscopic microscope is less, and the calibration precision of the stereoscopic microscope needs to be improved.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, provides a stereoscopic microscope calibration method based on coplanar points, improves the calibration precision of a stereoscopic microscope, and prepares for the accuracy of the image measurement result carried out subsequently.
As a first aspect of the present invention, there is provided a stereoscopic microscope calibration method based on a coplanar point, the stereoscopic microscope including a CCD camera, by calibrating a stereoscopic microscope through a calibration plate, the stereoscopic microscope calibration method based on the coplanar point comprising the steps of:
step S1: acquiring calibration plate image information acquired by the CCD camera;
step S2: establishing a CCD camera pinhole model, and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model;
step S3: according to the image information of the calibration plate and a relation formula between the pixel coordinate system and the world coordinate system, primarily calibrating the internal and external parameters of the CCD camera to obtain initial calibration values of the internal and external parameters of the CCD camera;
step S4: and optimizing the initial calibration value of the internal and external parameters of the CCD camera by adopting an LM algorithm-based light beam adjustment method so as to obtain the optimal calibration value of the internal and external parameters of the CCD camera.
Further, the establishing a CCD camera pinhole model, and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model, further includes:
the calibration of the stereoscopic microscope comprises the calibration of the internal parameters of the CCD camera and the calibration of the external parameters of the CCD camera; the internal parameters of the CCD camera comprise a scale factor f u 、f v And principal point coordinates (u) 0 ，v 0 ) The method comprises the steps of carrying out a first treatment on the surface of the The CCD camera external parameters comprise a translation matrix T and a rotation matrix R; in the calibration process, the internal parameters of the CCD camera are required to be obtained first, and the external parameters of the CCD camera are solved on the basis of obtaining the internal parameters;
the relation formula between the pixel coordinate system and the world coordinate system is established according to the CCD camera pinhole model, and is as follows:
wherein: s is a scale factor, f u 、f v Is the scale factor of a CCD camera, (u) 0 ，v 0 ) Is the principal point coordinate of the CCD camera, r 11 、r 21 、r 31 、r 12 、r 22 、r 32 、t x 、t y 、t z All are constants, A is the internal reference matrix of the CCD camera, RT is the external reference matrix of the CCD camera, (X) W ，Y W ) For the three-dimensional space coordinates of a point P in the calibration plate under the world coordinate system, (u, v) is the pixel coordinate of the point P under the pixel coordinate system.
Further, the preliminary calibration of the internal and external parameters of the CCD camera according to the calibration plate image information and the relation formula between the pixel coordinate system and the world coordinate system is performed to obtain an initial calibration value of the internal and external parameters of the CCD camera, and the method further includes:
the principal point coordinates (u) of the CCD camera are obtained by a variable magnification method 0 ，v 0 ) Calibrating;
calibration method based on coplanar pointsScale factor f of CCD camera u 、f v Calibrating;
and calibrating the translation matrix T and the rotation matrix R of the CCD camera by adopting a calibration method based on coplanar points.
Further, the method of using variable magnification method is to coordinate the principal point of the CCD camera (u 0 ，v 0 ) In the calibration, the method further comprises the following steps:
let the coordinates of any point in the calibration plate under the camera coordinate system be (X) c ,Y c ,Z c ) Ideally, the pixel coordinates (u ', v') of this point are:
wherein r is any amplification factor, (u) 0 ,v 0 ) The principal point coordinates of the CCD camera are obtained by eliminating r in the formula (2) to obtain a linear equation:
i.e. at any magnification, the pixel coordinates (u ', v') of the point are on the same line and the line must pass through the camera principal point coordinates (u 0 ,v 0 ) The method comprises the steps of carrying out a first treatment on the surface of the To find the camera principal point coordinates (u 0 ,v 0 ) Selecting 4 points in the calibration plate, wherein the 4 points are not overlapped on the image projection plane, respectively projecting the 4 points under different magnifications, fitting the obtained 4 straight lines by using a least square method, and obtaining the intersection point coordinates of the 4 straight lines by using the least square method, namely the principal point coordinates (u 0 ,v 0 )。
Further, the scaling factor f of the CCD camera is calibrated by adopting a calibration method based on coplanar points u 、f v In the calibration, the method further comprises the following steps:
by matrix multiplication, equation (1) is converted into:
wherein H is a homography matrix, H 1 ～h 8 Are all constants;
the scaling factors s and t are eliminated by equation (4) and equation (5) z The method comprises the following steps of:
for each corner on the checkerboard calibration plate, two equations of the formula (6) are corresponding, n corner can obtain n equation sets of the formula (6), wherein n is more than or equal to 4, the n equation sets are combined to obtain a matrix equation with the shape of AX=b, and A is a 2n×8 matrix;
three-dimensional space coordinates (X) of P point in the calibration plate W ，Y W ) And pixel coordinates (u, v) are normalized so that the coordinates are centered at the origin and at a mean value from the originUsing a svd decomposition method to solve for the value of X in the matrix equation ax=b; solving the value inverse normalization of X to obtain h 1 ～h 8 ；
The rotation matrix R itself has orthogonality, and thereforer 11 r 12 +r 21 r 22 +r 31 r 32 =0, continuing to separate equation (5) by combining the series of equations, and obtaining the scale factor f of the CCD camera by a series of mathematical transformations u And f v Is the value of (1):
wherein, the formula (7) is a homogeneous linear equation system with a unique linear solution, and f can be directly calculated u And f v Is a solution to (a).
Further, in the calibrating the translation matrix T and the rotation matrix R of the CCD camera by using the calibration method based on coplanar points, the method further includes:
in the process of solving the scale factor f u And f v Then, the translation matrix T and the rotation matrix R of the camera can be obtained; from the formulaCan calculate t z ；
Obtaining t z Then, a homography matrix H is obtained according to a formula (5); when H is known, the values of the first column elements and the second column elements of the translation matrix T and the rotation matrix R are found according to formula (9);
obtaining the value of the third column element of the rotation matrix R from the cross product of the first column and the second column of the rotation matrix R according to the orthogonality of the rotation matrix R;
and finally obtaining the rotation matrix R of the CCD camera according to the values of the first column element, the second column element and the third column element of the rotation matrix R.
Further, the optimization of the initial calibration value of the internal and external parameters of the CCD camera by adopting the light beam adjustment method based on the LM algorithm to obtain the optimal calibration value of the internal and external parameters of the CCD camera further comprises:
rotation matrix using rotation vector RvThe nine parameters in the process are reduced to three; let the unit vector r= [ r ] of the rotation vector Rv x r y r z ] T And the rotation angle is theta, the rotation angle theta is the modular length of the rotation vector Rv, the corresponding rotation matrix is R, and the conversion from R to R is shown as a formula (11):
wherein I is a third-order identity matrix; the conversion of R to R is in turn converted to equation (12):
the rotation vector Rv is obtained by multiplying a unit vector r by a module length theta, namely rv=r·θ, and only three parameters are provided; therefore, parameters to be optimized of the rotation matrix R are simplified to three, and the parameters to be optimized of the rotation matrix R are optimized by combining a camera distortion model, wherein the camera distortion model is described as a formula (13) and a formula (14):
wherein, (x) u ,y u ) Is the ideal image coordinates, (x d ,y d ) Is the coordinates of the image after the distortion,representing image pointsDistance to center point of image, k 1 、k 2 Is the radial distortion coefficient, p 1 ，p 2 Is a tangential distortion coefficient;
the obtained CCD camera calibration parameter value is used as an initial calibration value, an optimization algorithm formula (15) is utilized to integrally optimize the camera internal and external parameter initial calibration value, wherein the optimization of the rotation matrix R is that the rotation matrix R is firstly converted into a rotation vector Rv through a formula (12), then the rotation vector Rv is optimized through the formula (15) to obtain an optimized rotation vector Rv, and then the optimized rotation vector Rv is converted into an optimized rotation matrix R through a formula (11); the optimization of the internal and external parameters of the CCD camera is based on the maximum likelihood estimation criterion, and the optimization problem of the internal and external parameters of the CCD camera is expressed by the minimization problem of an optimization algorithm formula (15) for m multiplied by n calibration point coordinates provided by given n calibration plate images:
wherein M represents the total number of checkered corner points of the ith calibration plate image, n represents the total number of calibration plate images, M i,j Is a spatial point of the world coordinate system,representative point M i,j Converting into projection points of an ith calibration plate image according to the formula (1), the formula (13) and the formula (14), wherein A is an internal reference matrix of the camera, and k 1 ,k 2 Is the radial distortion coefficient, p 1 ,p 2 Is the tangential distortion coefficient, R i And T i Is the external reference matrix of the ith calibration plate image.
As a second aspect of the present invention, there is provided a stereoscopic microscope calibration device based on a coplanar point, comprising:
the acquisition module is used for acquiring the image information of the calibration plate acquired by the CCD camera;
the establishing module is used for establishing a CCD camera pinhole model and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model;
the calibration module is used for carrying out preliminary calibration on the internal and external parameters of the CCD camera according to the image information of the calibration plate and a relation formula between the pixel coordinate system and the world coordinate system so as to obtain initial calibration values of the internal and external parameters of the CCD camera;
and the optimization module is used for optimizing the internal and external parameter initial calibration value of the CCD camera by adopting an LM algorithm-based light beam adjustment method so as to obtain the internal and external parameter optimization calibration value of the CCD camera.
As a third aspect of the present invention, there is provided a stereoscopic microscope calibration system based on coplanar points, comprising a stereoscopic microscope and an industrial control computer, wherein the stereoscopic microscope comprises a CCD camera, the industrial control computer comprises the stereoscopic microscope calibration device based on coplanar points described above, the CCD camera is used for photographing a calibration plate to collect calibration plate image information, and the collected calibration plate image information is uploaded to the industrial control computer, and the industrial control computer completes calibration of the stereoscopic microscope.
Further, the calibration plate is placed on a precise numerical control displacement platform, and a region to be shot is positioned in a field of view of the stereoscopic microscope; the precise numerical control displacement platform is arranged together with a machine tool body through a guide rail, and the machine tool body is arranged on the ground; the stereoscopic microscope is arranged on the lathe bed through a guide rail; an LED light source for providing illumination is fixed in the stereoscopic microscope; the CCD camera is arranged on the stereoscopic microscope through threads; the stereoscopic microscope amplifies the image of the calibration plate, the CCD camera is used for collecting the amplified image information of the calibration plate, and the CCD camera transmits the amplified image information of the calibration plate to the industrial control computer through a network cable for image data processing.
The stereoscopic microscope calibration method based on the coplanar points has the following beneficial effects: the technical problems of more lenses, narrow view field, small depth of field, certain magnification and more distortion factors during the calibration of the stereoscopic microscope are solved, and the calibration precision of the stereoscopic microscope is improved.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate the invention and together with the description serve to explain, without limitation, the invention.
Fig. 1 is a flow chart of a stereoscopic microscope calibration method based on coplanar points.
Fig. 2 is a flowchart of a specific implementation of the stereoscopic microscope calibration method based on coplanar points.
FIG. 3 is a block diagram of the system for calibrating a stereoscopic microscope based on coplanar points.
In the figure: 1-a CCD camera; 2-stereoscopic microscope; 3-an LED light source; 4, a calibration plate; 5-an area to be shot; 6-a precise numerical control displacement platform; 7, a lathe bed; 8-an industrial control computer.
Detailed Description
In order to further describe the technical means and effects adopted by the invention to achieve the preset aim, the following detailed description refers to the specific implementation, structure, characteristics and effects of a stereoscopic microscope calibration method based on coplanar points according to the invention by combining the accompanying drawings and the preferred embodiment. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to fall within the scope of the invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe the embodiments of the invention herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In this embodiment, a stereoscopic microscope calibration method based on coplanar points is provided, and a stereoscopic microscope is calibrated through a calibration board, where the stereoscopic microscope includes a CCD camera, as shown in fig. 1, and the stereoscopic microscope calibration method based on coplanar points includes the following steps:
step S1: acquiring calibration plate image information acquired by the CCD camera;
step S2: establishing a CCD camera pinhole model, and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model;
preferably, the establishing a pinhole model of the CCD camera, and establishing a relational formula between a pixel coordinate system and a world coordinate system according to the pinhole model of the CCD camera, further includes:
in the pinhole imaging model, the common coordinate system is the world coordinate system O W -X W Y W Z W Camera coordinate system O C -X C Y C Z C Image coordinate system O s -xy and pixel coordinate system O-uv, wherein the X, y axes are respectively equal to X c ，Y c The axes are parallel. The representation of the point P in different coordinate systems is P W (X W ,Y W ,Z W ) In world coordinate system, P C (X C ,Y C ,Z C ) In the camera coordinate system, P (x, y) is in the image coordinate system and P (u, v) is in the pixel coordinate system.
The calibration of the stereoscopic microscope comprises the calibration of the internal parameters of the CCD camera and the calibration of the external parameters of the CCD camera; the internal parameters of the CCD camera comprise a scale factor f u 、f v And principal point coordinates (u) 0 ，v 0 ) The method comprises the steps of carrying out a first treatment on the surface of the The CCD camera external parameters comprise a translation matrix T and a rotation matrix R; in the calibration process, the C needs to be obtained firstSolving the external parameters of the CCD camera on the basis of solving the internal parameters of the CD camera;
the relation formula between the pixel coordinate system and the world coordinate system is established according to the CCD camera pinhole model, and is as follows:
wherein: s is a scale factor, f u 、f v Is the scale factor of a CCD camera, (u) 0 ，v 0 ) Is the principal point coordinate of the CCD camera, r 11 、r 21 、r 31 、r 12 、r 22 、r 32 、t x 、t y 、t z All are constants, A is the internal reference matrix of the CCD camera, RT is the external reference matrix of the CCD camera, (X) W ，Y W ) For the three-dimensional space coordinates of a point P in the calibration plate under the world coordinate system, (u, v) is the pixel coordinate of the point P under the pixel coordinate system.
Step S3: according to the image information of the calibration plate and a relation formula between the pixel coordinate system and the world coordinate system, primarily calibrating the internal and external parameters of the CCD camera to obtain initial calibration values of the internal and external parameters of the CCD camera;
preferably, as shown in fig. 2, the preliminary calibration of the internal and external parameters of the CCD camera according to the calibration plate image information and the relation formula between the pixel coordinate system and the world coordinate system is performed to obtain an initial calibration value of the internal and external parameters of the CCD camera, which further includes:
the principal point coordinates (u) of the CCD camera are obtained by a variable magnification method 0 ，v 0 ) Calibrating;
specifically, the method of using variable magnification method is used for measuring the principal point coordinates (u 0 ，v 0 ) In the calibration, the method further comprises the following steps:
let the coordinates of any point p in the calibration plate under the camera coordinate system be (X) c ,Y c ,Z c ) Ideally, the pixel coordinates (u ', v') The method comprises the following steps:
wherein r is any amplification factor, (u) 0 ,v 0 ) The principal point coordinates of the CCD camera are obtained by eliminating r in the formula (2) to obtain a linear equation:
i.e. at any magnification, the pixel coordinates (u ', v') of the point are on the same line and the line must pass through the camera principal point coordinates (u 0 ,v 0 ) The method comprises the steps of carrying out a first treatment on the surface of the To find the camera principal point coordinates (u 0 ,v 0 ) Selecting 4 points in the calibration plate, wherein the 4 points are not overlapped on the image projection plane, respectively projecting the 4 points under different magnifications, fitting the obtained 4 straight lines by using a least square method, and obtaining the intersection point coordinates of the 4 straight lines by using the least square method, namely the principal point coordinates (u 0 ,v 0 )。
Scaling factor f of the CCD camera by adopting a calibration method based on coplanar points u 、f v Calibrating;
specifically, the scaling factor f of the CCD camera is calibrated by adopting a calibration method based on coplanar points u 、f v In the calibration, the method further comprises the following steps:
under the condition that the principal point coordinates are known and nonlinear distortion and image coordinate perpendicularity are not considered, camera parameters which are not considered in any distortion can be obtained through an ideal perspective projection model; by matrix multiplication, equation (1) is converted into:
wherein H is a homography matrix, H 1 ～h 8 Are all constants;
the scaling factors s and t are eliminated by equation (4) and equation (5) z The method comprises the following steps of:
for each corner on the checkerboard calibration plate, two equations of the formula (6) are corresponding, n corner can obtain n equation sets of the formula (6), wherein n is more than or equal to 4, the n equation sets are combined to obtain a matrix equation with the shape of AX=b, and A is a 2n×8 matrix; in order to be able to find all unknown parameters of the matrix equation, it must be ensured that at least 4 points are taken.
It should be noted that the elements of the matrix a are in world coordinates, in pixel coordinates, and in products of the two terms, that is, the orders of magnitude of the respective elements of the matrix a are greatly different. Therefore, ax=b is a system of pathological equations, and the error of the result directly solved is large and must be improved. The eight-point algorithm of Hartley is utilized to improve A, data is normalized, and then solving is carried out, and the specific method is as follows:
(1) Translating the coordinates of a world coordinate system and a pixel coordinate system, so that the centroids of all the point sets are at the origin;
(2) Coordinate normalization processing, namely isotropically scaling the coordinates of the points to ensure that the average distance from the point to the origin is 2;
the pathological condition of the equation can be removed through normalization treatment, and a better result is obtained.
Three-dimensional space coordinates (X) of P point in the calibration plate W ，Y W ) And pixel coordinates (u, v) are normalized so that the coordinates are centered at the origin and at a mean value from the originDecomposition using svdSolving a value of X in a matrix equation AX=b by a method; solving the value inverse normalization of X to obtain h 1 ～h 8 ；
The rotation matrix R itself has orthogonality, and thereforer 11 r 12 +r 21 r 22 +r 31 r 32 =0, continuing to separate equation (5) by combining the series of equations, and obtaining the scale factor f of the CCD camera by a series of mathematical transformations u And f v Is the value of (1):
wherein, the formula (7) is a homogeneous linear equation system with a unique linear solution, and f can be directly calculated u And f v Is a solution to (a). However, f obtained by using this direct method u And f v Is sensitive to noise and is easily influenced by error factors such as angular point extraction errors, imaging errors of cameras and the like. H obtained by solving each image 1 ～h 8 All of which are different, both equations of equation (7) are generated. In order to improve the robustness of the solving result, n images can obtain n equation sets, the n equation sets are combined to form a 2n multiplied by 2 homogeneous linear equation set, and the linear least square method is used for solving to obtain f u And f v Is a solution to (a). The advantage of this solution is that all images are considered simultaneously, and the result has good noise immunity and is less affected by errors.
And calibrating the translation matrix T and the rotation matrix R of the CCD camera by adopting a calibration method based on coplanar points.
Specifically, the calibrating the translation matrix T and the rotation matrix R of the CCD camera by adopting the calibration method based on coplanar points further includes:
in the process of solving the scale factor f u And f v Then, the translation matrix T and the rotation matrix R of the camera can be obtained; from the formulaCan calculate t z ；
Obtaining t z Then, a homography matrix H is obtained according to a formula (5); when H is known, the values of the first column elements and the second column elements of the translation matrix T and the rotation matrix R are found according to formula (9);
obtaining the value of the third column element of the rotation matrix R from the cross product of the first column and the second column of the rotation matrix R according to the orthogonality of the rotation matrix R;
and finally obtaining the rotation matrix R of the CCD camera according to the values of the first column element, the second column element and the third column element of the rotation matrix R.
Step S4: and optimizing the initial calibration value of the internal and external parameters of the CCD camera by adopting an LM algorithm-based light beam adjustment method so as to obtain the optimal calibration value of the internal and external parameters of the CCD camera.
Preferably, the optimization of the initial calibration value of the internal and external parameters of the CCD camera by using the LM algorithm-based optical beam adjustment method to obtain the optimal calibration value of the internal and external parameters of the CCD camera further includes:
after the internal and external parameters of the CCD camera are calibrated preliminarily, the internal and external parameters are optimized to obtain distortion coefficients and optimized internal and external parameters, and in order to simplify the optimized parameters, the invention adopts a rotation vector Rv to rotate a matrixThe nine parameters in the process are reduced to three; let the unit vector r= [ r ] of the rotation vector Rv x r y r z ] T And the rotation angle is theta, the rotation angle theta is the modular length of the rotation vector Rv, the corresponding rotation matrix is R, and the conversion from R to R is shown as a formula (11):
wherein I is a third-order identity matrix; the conversion of R to R is in turn converted to equation (12):
the rotation vector Rv is obtained by multiplying a unit vector r by a module length theta, namely rv=r·θ, and only three parameters are provided; therefore, parameters to be optimized of the rotation matrix R are simplified into three, and the main parameters are optimized by considering the influence of radial distortion and tangential distortion; optimizing parameters to be optimized of the rotation matrix R in combination with a camera distortion model, wherein the camera distortion model taking radial distortion and tangential distortion into consideration is described as formula (13) and formula (14):
wherein, (x) u ,y u ) Is the ideal image coordinates, (x d ,y d ) Is the coordinates of the image after the distortion,representing the distance of an image point from the center point of the image, k 1 、k 2 Is the radial distortion coefficient, p 1 ，p 2 Is a tangential distortion coefficient;
the obtained CCD camera calibration parameter value is used as an initial calibration value, an optimization algorithm formula (15) is utilized to integrally optimize the camera internal and external parameter initial calibration value, wherein the optimization of the rotation matrix R is that the rotation matrix R is firstly converted into a rotation vector Rv through a formula (12), then the rotation vector Rv is optimized through the formula (15) to obtain an optimized rotation vector Rv, and then the optimized rotation vector Rv is converted into an optimized rotation matrix R through a formula (11); the optimization of the internal and external parameters of the CCD camera is based on the maximum likelihood estimation criterion, and the optimization problem of the internal and external parameters of the CCD camera is expressed by the minimization problem of an optimization algorithm formula (15) for m multiplied by n calibration point coordinates provided by given n calibration plate images:
wherein M represents the total number of checkered corner points of the ith calibration plate image, n represents the total number of calibration plate images, M i,j Is a spatial point of the world coordinate system,representative point M i,j Converting into projection points of an ith calibration plate image according to the formula (1), the formula (13) and the formula (14), wherein A is an internal reference matrix of the camera, and k 1 ,k 2 Is the radial distortion coefficient, p 1 ,p 2 Is the tangential distortion coefficient, R i And T i Is the external reference matrix of the ith calibration plate image.
The invention adopts an LM algorithm-based beam adjustment method to solve the problem of minimizing and optimizing the formula (15); the parameters of the CCD camera to be optimized are optimized by minimizing the objective function, equation (15).
As shown in fig. 2, the method for calibrating the stereoscopic microscope based on the coplanar points provided by the invention comprises the following specific steps: the invention adopts a mode of relatively fixing the camera, and adopts a precision-machined checkerboard calibration plate to calibrate the camera.Regarding the principal point coordinates, considering that the principal point is actually the intersection point of the optical axis and the CCD imaging surface, when the magnification of the microscope is changed, the position of the optical axis is actually unchanged, that is, the principal point coordinates of the camera are always unchanged; at any magnification, point (X c ,Y c ,Z c ) Is on the same straight line and the straight line must pass through the principal point (u) 0 ,v 0 ). In this way, n spatial points with non-overlapping projections on the image plane can form n straight lines intersecting at the same point by projection under different magnifications; the coordinates of this intersection point are the camera principal point coordinates. The specific operation steps of realizing the calibration of the main point coordinates by adopting a variable multiplying power method are as follows: selecting 4 points which are not overlapped on an image projection plane, respectively projecting the 4 points under 5, 10 and 20 of different magnification, fitting the obtained 4 straight lines by using a least square method, and solving the intersection point coordinates of the 4 straight lines, namely a main point of the camera by using the least square method; the Zhang's camera calibration method requires a large angular relationship between different calibration plate pictures, and the optimal angle is usually 45 degrees. The depth factor of the stereo microscope is limited, when the angle between the calibration plate and the horizontal plane exceeds 20 degrees, a plurality of fuzzy angular points can appear in the view field, in order to stably obtain the scale factor of the camera, and summarizing the experimental process of Zhang's calibration, the more the number of pictures of the calibration plate is found, the less the number of pictures of the calibration plate which are parallel to each other is, the more stable the scale factor of the camera can be obtained, so the specific steps of calibrating the scale factor of the camera are as follows: the rotation of the calibration plate is divided into two modes of rotation along a horizontal axis and rotation along a vertical axis, and the rotation of the vertical axis is 40 degrees each time, so that nine horizontal angle positions exist on the calibration plate. And (3) carrying out horizontal axis rotation at each horizontal angle position, dividing the horizontal axis rotation position of the calibration plate into three positions of +10 degrees, 0 degrees and-10 degrees, and shooting an image of the calibration plate at each position. The whole calibration process of the scale factors is to shoot 27 calibration plate pictures altogether. The initial value of the scale factor can be obtained through the formulas (4) to (7), and the initial value of the camera external parameter can be obtained through the formulas (8) to (10).
And (3) adopting a beam adjustment method to optimize internal and external parameters: and (3) inputting an imaging equation, a space point image coordinate observation value and a parameter initial value to be optimized in an optimization program, wherein the output of the program is an optimized calibration parameter value which minimizes the output of the formula (15).
As another embodiment of the present invention, there is provided a stereoscopic microscope calibration device based on coplanar points, including:
the acquisition module is used for acquiring the image information of the calibration plate acquired by the CCD camera;
the establishing module is used for establishing a CCD camera pinhole model and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model;
the calibration module is used for carrying out preliminary calibration on the internal and external parameters of the CCD camera according to the image information of the calibration plate and a relation formula between the pixel coordinate system and the world coordinate system so as to obtain initial calibration values of the internal and external parameters of the CCD camera;
and the optimization module is used for optimizing the internal and external parameter initial calibration value of the CCD camera by adopting an LM algorithm-based light beam adjustment method so as to obtain the internal and external parameter optimization calibration value of the CCD camera.
As another embodiment of the present invention, as shown in fig. 3, a stereoscopic microscope calibration system based on coplanar points is provided, which includes a stereoscopic microscope 2 and an industrial control computer 8, the stereoscopic microscope 2 includes a CCD camera 1, the industrial control computer 8 includes the stereoscopic microscope calibration device based on coplanar points, the CCD camera 1 is used for photographing a calibration plate 4 to collect calibration plate image information, and upload the collected calibration plate image information to the industrial control computer 8, and the industrial control computer 8 calibrates the stereoscopic microscope through the obtained calibration plate image, so as to establish a final imaging model of the relationship between the world coordinate system and the pixel coordinate system.
Specifically, the calibration plate 4 is placed on a precise numerical control displacement platform 6, and a region 5 to be shot is positioned in the field of view of the stereoscopic microscope; the precise numerical control displacement platform 6 is arranged together with the machine tool body 7 through a guide rail, and can meet the high-precision translation requirement of the checkerboard calibration plate in the calibration experiment; the machine tool body 7 is arranged on the ground; the stereoscopic microscope 2 is arranged on a machine tool body 7 through a guide rail; an LED light source 3 for providing illumination is fixed in the stereoscopic microscope 2; the CCD camera 1 is arranged on the stereoscopic microscope 2 through threads; the stereo microscope 2 amplifies the image of the calibration plate 4, the CCD camera 1 is used for collecting the amplified image information of the calibration plate 4, and the CCD camera 1 transmits the amplified image information of the calibration plate 4 to the industrial control computer 8 through a network cable for image data processing. The CCD camera is calibrated by adopting a checkerboard calibration plate with higher precision.
In the embodiment of the invention, the CCD camera 1 is used for shooting the image information of the calibration plate, and the CCD camera adopts a large constant image MER2-2000-6GC camera with image resolution: 5496×3672, acquisition speed: 5.8fps. The magnification of the microscope lens used in the stereoscopic microscope 2 is 5 times, 10 times, 20 times, and 100 times. The motion travel of the precise numerical control displacement platform 6 is X350X Y350X Z200mm. In order to realize the calibration of the microscopic stereoscopic vision system, a glass substrate checkerboard calibration plate is adopted as a calibration plate required for the calibration. The grid size of the calibration plate is 0.1mm multiplied by 0.1mm, the whole width of the checkerboard pattern is 1mm multiplied by 1mm, the manufacturing precision is 1 mu m, and the requirements of the calibration of a stereoscopic microscope can be met.
In summary, the stereoscopic microscope calibration method based on the coplanar points provided by the invention is characterized in that the CCD camera calibration is realized by utilizing a high-precision checkerboard calibration plate, and the method mainly comprises the steps of realizing the calibration of main point coordinates by adopting a variable magnification method, the calibration of scale factors by adopting a calibration method based on the coplanar points, and the optimization of main parameters and distortion parameters by adopting a beam adjustment method. And finally, judging the accuracy of calibration by calculating the re-projection error.
The invention solves the technical difficulties of multiple lenses, narrow view field, small depth of field, certain magnification and more distortion factors during the calibration of the stereoscopic microscope, and improves the calibration precision of the stereoscopic microscope.
The present invention is not limited to the above-mentioned embodiments, but is intended to be limited to the following embodiments, and any modifications, equivalents and modifications can be made to the above-mentioned embodiments without departing from the scope of the invention.
Claims (10)
1. The stereoscopic microscope calibration method based on the coplanar points is characterized by comprising the following steps of:
step S1: acquiring calibration plate image information acquired by the CCD camera;
step S2: establishing a CCD camera pinhole model, and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model;
step S3: according to the image information of the calibration plate and a relation formula between the pixel coordinate system and the world coordinate system, primarily calibrating the internal and external parameters of the CCD camera to obtain initial calibration values of the internal and external parameters of the CCD camera;
step S4: and optimizing the initial calibration value of the internal and external parameters of the CCD camera by adopting an LM algorithm-based light beam adjustment method so as to obtain the optimal calibration value of the internal and external parameters of the CCD camera.
2. The method for calibrating a stereoscopic microscope based on coplanar points according to claim 1, wherein the establishing a CCD camera pinhole model and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model further comprises:
said stereoscopic microscopeThe calibration of the lens comprises the calibration of the internal parameters of the CCD camera and the calibration of the external parameters of the CCD camera; the internal parameters of the CCD camera comprise a scale factor f u 、f v And principal point coordinates (u) 0 ，v 0 ) The method comprises the steps of carrying out a first treatment on the surface of the The CCD camera external parameters comprise a translation matrix T and a rotation matrix R; in the calibration process, the internal parameters of the CCD camera are required to be obtained first, and the external parameters of the CCD camera are solved on the basis of obtaining the internal parameters;
the relation formula between the pixel coordinate system and the world coordinate system is established according to the CCD camera pinhole model, and is as follows:
wherein: s is a scale factor, f u 、f v Is the scale factor of a CCD camera, (u) 0 ，v 0 ) Is the principal point coordinate of the CCD camera, r 11 、r 21 、r 31 、r 12 、r 22 、r 32 、t x 、t y 、t z All are constants, A is the internal reference matrix of the CCD camera, RT is the external reference matrix of the CCD camera, (X) W ，Y W ) For the three-dimensional space coordinates of a point P in the calibration plate under the world coordinate system, (u, v) is the pixel coordinate of the point P under the pixel coordinate system.
3. The stereoscopic microscope calibration method based on coplanar points according to claim 2, wherein the preliminary calibration of the internal and external parameters of the CCD camera according to the calibration plate image information and the relation formula between the pixel coordinate system and the world coordinate system is performed to obtain the initial calibration value of the internal and external parameters of the CCD camera, further comprising:
the principal point coordinates (u) of the CCD camera are obtained by a variable magnification method 0 ，v 0 ) Calibrating;
scaling factor f of the CCD camera by adopting a calibration method based on coplanar points u 、f v Calibrating;
and calibrating the translation matrix T and the rotation matrix R of the CCD camera by adopting a calibration method based on coplanar points.
4. A stereoscopic microscope calibration method based on coplanar points according to claim 3, wherein the principal point coordinates (u 0 ，v 0 ) In the calibration, the method further comprises the following steps:
let the coordinates of any point in the calibration plate under the camera coordinate system be (X) c ,Y c ,Z c ) Ideally, the pixel coordinates (u ', v') of this point are:
wherein r is any amplification factor, (u) 0 ,v 0 ) The principal point coordinates of the CCD camera are obtained by eliminating r in the formula (2) to obtain a linear equation:
i.e. at any magnification, the pixel coordinates (u ', v') of the point are on the same line and the line must pass through the camera principal point coordinates (u 0 ,v 0 ) The method comprises the steps of carrying out a first treatment on the surface of the To find the camera principal point coordinates (u 0 ,v 0 ) Selecting 4 points in the calibration plate, wherein the 4 points are not overlapped on the image projection plane, respectively projecting the 4 points under different magnifications, fitting the obtained 4 straight lines by using a least square method, and obtaining the intersection point coordinates of the 4 straight lines by using the least square method, namely the principal point coordinates (u 0 ,v 0 )。
5. A method of calibrating a stereoscopic microscope based on coplanar points according to claim 3, wherein the method of calibrating the scale factor f of the CCD camera based on coplanar points is adopted u 、f v In the calibration, the method further comprises the following steps:
by matrix multiplication, equation (1) is converted into:
wherein H is a homography matrix, H 1 ～h 8 Are all constants;
the scaling factors s and t are eliminated by equation (4) and equation (5) z The method comprises the following steps of:
for each corner on the checkerboard calibration plate, two equations of the formula (6) are corresponding, n corner can obtain n equation sets of the formula (6), wherein n is more than or equal to 4, the n equation sets are combined to obtain a matrix equation with the shape of AX=b, and A is a 2n×8 matrix;
three-dimensional space coordinates (X) of P point in the calibration plate W ，Y W ) And pixel coordinates (u, v) are normalized so that the coordinates are centered at the origin and at a mean value from the originUsing a svd decomposition method to solve for the value of X in the matrix equation ax=b; solving the value inverse normalization of X to obtain h 1 ～h 8 ；
The rotation matrix R itself has orthogonality, and thereforer 11 r 12 +r 21 r 22 +r 31 r 32 =0, continuing to separate equation (5) by combining the series of equations, and obtaining the scale factor f of the CCD camera by a series of mathematical transformations u And f v Is the value of (1):
wherein, the formula (7) is a homogeneous linear equation system with a unique linear solution, and f can be directly calculated u And f v Is a solution to (a).
6. The method for calibrating a stereoscopic microscope based on coplanar points according to claim 5, wherein the calibrating the translation matrix T and the rotation matrix R of the CCD camera by using the coplanar point-based calibration method further comprises:
in the process of solving the scale factor f u And f v Then, the translation matrix T and the rotation matrix R of the camera can be obtained; from the formula Can calculate t z ；
Obtaining t z Then, a homography matrix H is obtained according to a formula (5); when H is known, the values of the first column elements and the second column elements of the translation matrix T and the rotation matrix R are found according to formula (9);
obtaining the value of the third column element of the rotation matrix R from the cross product of the first column and the second column of the rotation matrix R according to the orthogonality of the rotation matrix R;
and finally obtaining the rotation matrix R of the CCD camera according to the values of the first column element, the second column element and the third column element of the rotation matrix R.
7. The stereoscopic microscope calibration method based on coplanar points according to claim 6, wherein the optimization of the initial calibration value of the internal and external parameters of the CCD camera by using the LM algorithm-based beam adjustment method to obtain the optimized calibration value of the internal and external parameters of the CCD camera further comprises:
rotation matrix using rotation vector RvThe nine parameters in the process are reduced to three; let the unit vector r= [ r ] of the rotation vector Rv x r y r z ] T And the rotation angle is theta, the rotation angle theta is the modular length of the rotation vector Rv, the corresponding rotation matrix is R, and the conversion from R to R is shown as a formula (11):
wherein I is a third-order identity matrix; the conversion of R to R is in turn converted to equation (12):
the rotation vector Rv is obtained by multiplying a unit vector r by a module length theta, namely rv=r·θ, and only three parameters are provided; therefore, parameters to be optimized of the rotation matrix R are simplified to three, and the parameters to be optimized of the rotation matrix R are optimized by combining a camera distortion model, wherein the camera distortion model is described as a formula (13) and a formula (14):
wherein, (x) u ,y u ) Is the ideal image coordinates, (x d ,y d ) Is the coordinates of the image after the distortion,representing the distance of an image point from the center point of the image, k 1 、k 2 Is the radial distortion coefficient, p 1 ，p 2 Is a tangential distortion coefficient;
the obtained CCD camera calibration parameter value is used as an initial calibration value, an optimization algorithm formula (15) is utilized to integrally optimize the camera internal and external parameter initial calibration value, wherein the optimization of the rotation matrix R is that the rotation matrix R is firstly converted into a rotation vector Rv through a formula (12), then the rotation vector Rv is optimized through the formula (15) to obtain an optimized rotation vector Rv, and then the optimized rotation vector Rv is converted into an optimized rotation matrix R through a formula (11); the optimization of the internal and external parameters of the CCD camera is based on the maximum likelihood estimation criterion, and the optimization problem of the internal and external parameters of the CCD camera is expressed by the minimization problem of an optimization algorithm formula (15) for m multiplied by n calibration point coordinates provided by given n calibration plate images:
wherein M represents the total number of checkered corner points of the ith calibration plate image, n represents the total number of calibration plate images, M i,j Is the worldThe spatial points of the world coordinate system,representative point M i,j Converting into projection points of an ith calibration plate image according to the formula (1), the formula (13) and the formula (14), wherein A is an internal reference matrix of the camera, and k 1 ,k 2 Is the radial distortion coefficient, p 1 ,p 2 Is the tangential distortion coefficient, R i And T i Is the external reference matrix of the ith calibration plate image.
8. A stereoscopic microscope calibration device based on coplanar points, for implementing the stereoscopic microscope calibration method based on coplanar points according to any one of claims 1 to 7, characterized in that the stereoscopic microscope calibration device based on coplanar points comprises:
the acquisition module is used for acquiring the image information of the calibration plate acquired by the CCD camera;
the establishing module is used for establishing a CCD camera pinhole model and establishing a relation formula between a pixel coordinate system and a world coordinate system according to the CCD camera pinhole model;
the calibration module is used for carrying out preliminary calibration on the internal and external parameters of the CCD camera according to the image information of the calibration plate and a relation formula between the pixel coordinate system and the world coordinate system so as to obtain initial calibration values of the internal and external parameters of the CCD camera;
and the optimization module is used for optimizing the internal and external parameter initial calibration value of the CCD camera by adopting an LM algorithm-based light beam adjustment method so as to obtain the internal and external parameter optimization calibration value of the CCD camera.
9. The stereoscopic microscope calibration system based on the coplanar points is characterized by comprising a stereoscopic microscope (2) and an industrial control computer (8), wherein the stereoscopic microscope (2) comprises a CCD (charge coupled device) camera (1), the industrial control computer (8) comprises the stereoscopic microscope calibration device based on the coplanar points, the CCD camera (1) is used for shooting a calibration plate (4) so as to acquire calibration plate image information, the acquired calibration plate image information is uploaded to the industrial control computer (8), and the industrial control computer (8) finishes the calibration of the stereoscopic microscope.
10. The stereoscopic microscope calibration system based on coplanar points according to claim 9, characterized in that the calibration plate (4) is placed on a precision numerically controlled displacement platform (6), the area (5) to be photographed of which is located within the field of view of the stereoscopic microscope; the precise numerical control displacement platform (6) is arranged together with a machine tool body (7) through a guide rail, and the machine tool body (7) is arranged on the ground; the stereoscopic microscope (2) is arranged on a machine tool body (7) through a guide rail; an LED light source (3) for providing illumination is fixed in the stereoscopic microscope (2); the CCD camera (1) is arranged on the stereoscopic microscope (2) through threads; the stereoscopic microscope (2) amplifies the image of the calibration plate (4), the CCD camera (1) is used for collecting the amplified image information of the calibration plate (4), and the CCD camera (1) transmits the amplified image information of the calibration plate (4) to the industrial control computer (8) through a network cable for image data processing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310935422.7A CN116977444A (en) | 2023-07-28 | 2023-07-28 | Stereoscopic microscope calibration method, device and system based on coplanar points |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310935422.7A CN116977444A (en) | 2023-07-28 | 2023-07-28 | Stereoscopic microscope calibration method, device and system based on coplanar points |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116977444A true CN116977444A (en) | 2023-10-31 |
Family
ID=88477776
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310935422.7A Withdrawn CN116977444A (en) | 2023-07-28 | 2023-07-28 | Stereoscopic microscope calibration method, device and system based on coplanar points |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116977444A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103247053A (en) * | 2013-05-16 | 2013-08-14 | 大连理工大学 | Accurate part positioning method based on binocular microscopy stereo vision |
| CN107507246A (en) * | 2017-08-21 | 2017-12-22 | 南京理工大学 | A kind of camera marking method based on improvement distortion model |
| CN116071433A (en) * | 2022-12-08 | 2023-05-05 | 深圳市华汉伟业科技有限公司 | Camera calibration method and system, and computer-readable storage medium |
-
2023
- 2023-07-28 CN CN202310935422.7A patent/CN116977444A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103247053A (en) * | 2013-05-16 | 2013-08-14 | 大连理工大学 | Accurate part positioning method based on binocular microscopy stereo vision |
| CN107507246A (en) * | 2017-08-21 | 2017-12-22 | 南京理工大学 | A kind of camera marking method based on improvement distortion model |
| CN116071433A (en) * | 2022-12-08 | 2023-05-05 | 深圳市华汉伟业科技有限公司 | Camera calibration method and system, and computer-readable storage medium |
Non-Patent Citations (4)
| Title |
|---|
| 刘杨豪: "基于共面点的改进摄像机标定方法研究", 《计算机工程》, vol. 42, no. 8, 31 August 2016 (2016-08-31), pages 289 - 294 * |
| 叶峰: "共面点的摄像机非线性畸变校正", 《光学 精密工程》, vol. 23, no. 10, 31 October 2015 (2015-10-31), pages 2962 - 2970 * |
| 周佳乐: "基于二维图像和三维点云的相机空间位姿估计", 《硕士学位论文电子期刊》, 11 November 2022 (2022-11-11), pages 12 - 19 * |
| 崔凌燕: "基于两步法的摄像机标定算法", 《 测试技术学报 》, vol. 32, no. 2, 31 December 2018 (2018-12-31), pages 125 - 130 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107014312B (en) | A kind of integral calibrating method of mirror-vibrating line laser structured light three-dimension measuring system | |
| CN106408556B (en) | A kind of small items measuring system scaling method based on general imaging model | |
| Orteu et al. | Multiple-camera instrumentation of a single point incremental forming process pilot for shape and 3D displacement measurements: methodology and results | |
| CN109859272B (en) | Automatic focusing binocular camera calibration method and device | |
| CN104729429A (en) | Calibration method of telecentric imaging three-dimension topography measuring system | |
| WO2018201677A1 (en) | Bundle adjustment-based calibration method and device for telecentric lens-containing three-dimensional imaging system | |
| CN109579695B (en) | Part measuring method based on heterogeneous stereoscopic vision | |
| CN109615661A (en) | Light-field camera intrinsic parameter caliberating device and method | |
| CN102221331B (en) | Measuring method based on asymmetric binocular stereovision technology | |
| CN109961485A (en) | A method of target positioning is carried out based on monocular vision | |
| WO2021129437A1 (en) | Method and system for light calibration field camera without requiring white image | |
| Chen et al. | Self-recalibration of a colour-encoded light system for automated three-dimensional measurements | |
| CN112489137A (en) | RGBD camera calibration method and system | |
| US7349584B2 (en) | Method for correcting distortions in multi-focus image stacks | |
| CN110136211A (en) | A kind of workpiece localization method and system based on active binocular vision technology | |
| CN113724337B (en) | Camera dynamic external parameter calibration method and device without depending on tripod head angle | |
| CN109974618A (en) | The overall calibration method of multisensor vision measurement system | |
| CN110136068A (en) | Sound film top dome assembly system based on location position between bilateral telecentric lens camera | |
| CN109540041A (en) | Binocular active vision vector orthonomalization automobile shape measurement system and method | |
| CN114359405A (en) | Calibration method of off-axis Samm 3D line laser camera | |
| CN112229323A (en) | Six-degree-of-freedom measurement method of checkerboard cooperative target based on monocular vision of mobile phone and application of six-degree-of-freedom measurement method | |
| CN116740187A (en) | Multi-camera combined calibration method without overlapping view fields | |
| CN112797900B (en) | Multi-camera plate size measuring method | |
| CN111583342A (en) | Target rapid positioning method and device based on binocular vision | |
| CN115082538A (en) | System and method for three-dimensional reconstruction of surface of multi-view vision balance ring part based on line structure light projection |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WW01 | Invention patent application withdrawn after publication |
Application publication date: 20231031 |
|
| WW01 | Invention patent application withdrawn after publication |