CN113177989A - Intraoral scanner calibration method and device - Google Patents
Intraoral scanner calibration method and device Download PDFInfo
- Publication number
- CN113177989A CN113177989A CN202110494766.XA CN202110494766A CN113177989A CN 113177989 A CN113177989 A CN 113177989A CN 202110494766 A CN202110494766 A CN 202110494766A CN 113177989 A CN113177989 A CN 113177989A
- Authority
- CN
- China
- Prior art keywords
- calibration
- pairs
- intraoral scanner
- image
- matrix
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 28
- 239000011159 matrix material Substances 0.000 claims abstract description 67
- 238000004364 calculation method Methods 0.000 claims abstract description 7
- 230000004927 fusion Effects 0.000 claims abstract description 7
- 230000003287 optical effect Effects 0.000 claims description 32
- 239000013598 vector Substances 0.000 claims description 30
- 238000006073 displacement reaction Methods 0.000 claims description 8
- 238000003384 imaging method Methods 0.000 claims description 8
- 238000010586 diagram Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 3
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000010606 normalization Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
Images
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
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
- G06F17/16—Matrix or vector computation, e.g. matrix-matrix or matrix-vector multiplication, matrix factorization
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/30—Subject of image; Context of image processing
- G06T2207/30244—Camera pose
Abstract
The invention discloses a calibration method and a device of an intraoral scanner, wherein the method comprises the following steps: based on a deflectable calibration plate arranged in a calibration cylinder, two groups of image data displayed by the calibration plate under two different light paths are collected by a scanning head; dividing the two groups of image data into a plurality of pairs of calibration image pairs by taking the same deflection angle as a combination basis, wherein two calibration images contained in each pair of calibration image pairs are in a mirror image relationship with each other; extracting a plurality of pairs of matching point pairs from each pair of calibration image pairs, and solving a relevant homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs; and performing fusion calculation by combining the plurality of homography matrixes obtained by solving to obtain all internal and external parameters of the intraoral scanner. In the embodiment of the invention, one-time calibration process of the intraoral scanner can be realized by arranging the calibration cylinder, and the operation workload of the system is greatly reduced.
Description
Technical Field
The invention relates to the technical field of parameter calibration, in particular to a calibration method and device for an intraoral scanner.
Background
The current camera calibration technology refers to establishing a camera imaging geometric model and correcting lens distortion, namely acquiring coordinate information corresponding to an object in a real three-dimensional world through image information shot by a camera, establishing a geometric model of the object mapped to a camera imaging plane from the three-dimensional world by using internal and external parameters of the camera, and finally enabling an imaged object image to be consistent with an object image in the real three-dimensional world. However, the existing calibration scheme needs to satisfy the requirement that the whole optical system of the measuring device is fixed, and when the scanning head utilized by the oral scanner is replaced once, the system needs to perform a calibration operation again, thereby increasing the operation workload of the system.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, and provides a calibration method and a calibration device for an intraoral scanner.
In order to solve the above problems, the present invention provides an intraoral scanner calibration method, including:
based on a deflectable calibration plate arranged in a calibration cylinder, two groups of image data displayed by the calibration plate under two different light paths are collected by a scanning head;
dividing the two groups of image data into a plurality of pairs of calibration image pairs by taking the same deflection angle as a combination basis, wherein two calibration images contained in each pair of calibration image pairs are in a mirror image relationship with each other;
extracting a plurality of pairs of matching point pairs from each pair of calibration image pairs, and solving a relevant homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs;
and performing fusion calculation by combining the plurality of homography matrixes obtained by solving to obtain all internal and external parameters of the intraoral scanner.
Optionally, an adjusting buckle is arranged on the calibration cylinder, and the adjusting buckle is controlled by an operating system of the intraoral scanner and is used for orderly adjusting the deflection angle of the calibration plate according to a set rule.
Optionally, when the calibration board adjusts the deflection angle according to a set rule, the spatial position corresponding to the image data acquired by the scanning head at the current angle is increased to a specific displacement compared with the spatial position corresponding to the image data acquired at the previous angle.
Optionally, the extracting a plurality of pairs of matching point pairs from each pair of calibration image pairs, and solving a corresponding homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs includes:
obtaining the pixel coordinates corresponding to the ith (i is more than or equal to 1 and less than or equal to 4) pair of matching points as Pi(xi,yi)、P′i(x′i,y′i)；
Determining PiPoint and P'iThe relationship between points is:
converting the relation to obtain:
because the homography matrix H is a homogeneous matrix, the homography matrix H is rewritten into a vector expression mode as follows: h ═ H (H)11,H12,H13,H21,H22，H23,H31,H32,1)TFurther, the above multivariate equation set is rewritten as:
and (3) enabling i to be i +1, and executing the steps in a circulating manner until four groups of constant vectors associated with the four pairs of matching points are obtained, combining the four groups of constant vectors to form a constant matrix A, solving all matrix elements contained in the vector H by using a relational expression Ah to be 0, and further obtaining a homography matrix H associated with the current calibration image pair.
Optionally, the relationship between each homography matrix and all internal and external parameters of the intraoral scanner is as follows:
wherein s is a scale factor and (u)0,v0) Is the coordinate of the projection point, f, presented when the center of the optical axis is projected to the imaging plane along the direction of the z-axisxIs the physical size, f, of any pixel point in the x-axis directionyIs the physical size of any pixel point in the y-axis direction, gamma is the distortion coefficient, r1、r2For two elements in the rotation matrix R, t is the translation vector.
In addition, the embodiment of the invention also provides a calibration device of the intraoral scanner, which comprises:
the image acquisition module is used for acquiring two groups of image data of the calibration plate under two different light paths by utilizing the scanning head based on the fact that the calibration plate which can deflect is arranged in the calibration cylinder;
the image dividing module is used for dividing the two groups of image data into a plurality of pairs of calibration image pairs by taking the same deflection angle as a combination basis, and two calibration images contained in each pair of calibration image pairs are in a mirror image relationship with each other;
the matrix solving module is used for extracting a plurality of pairs of matching point pairs from each pair of calibration image pairs and solving a relevant homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs;
and the parameter acquisition module is used for carrying out fusion calculation by combining the plurality of homography matrixes obtained by solving to obtain all internal and external parameters of the intraoral scanner.
Optionally, an adjusting buckle is arranged on the calibration cylinder, and the adjusting buckle is controlled by an operating system of the intraoral scanner and is used for orderly adjusting the deflection angle of the calibration plate according to a set rule.
Optionally, when the calibration board adjusts the deflection angle according to a set rule, the spatial position corresponding to the image data acquired by the scanning head at the current angle is increased to a specific displacement compared with the spatial position corresponding to the image data acquired at the previous angle.
Optionally, the matrix solving module is further configured to obtain pixel coordinates P corresponding to the ith (i is greater than or equal to 1 and less than or equal to 4) pair of matching pointsi(xi，yi)、P′i(x′i,y′i)；
Determining PiPoint and P'iThe relationship between points is:
converting the relation to obtain:
because the homography matrix H is a homogeneous matrix, the homography matrix H is rewritten into a vector expression mode as follows: h ═ H (H)11,H12,H13,H21，H22，H23,H31,H32,1)TFurther, the above multivariate equation set is rewritten as:
and (3) enabling i to be i +1, and executing the steps in a circulating manner until four groups of constant vectors associated with the four pairs of matching points are obtained, combining the four groups of constant vectors to form a constant matrix A, solving all matrix elements contained in the vector H by using a relational expression Ah to be 0, and further obtaining a homography matrix H associated with the current calibration image pair.
Optionally, the relationship between each homography matrix and all internal and external parameters of the intraoral scanner is as follows:
wherein s is a scale factor and (u)0,v0) Is the coordinate of the projection point, f, presented when the center of the optical axis is projected to the imaging plane along the direction of the z-axisxIs the physical size, f, of any pixel point in the x-axis directionyIs the physical size of any pixel point in the y-axis direction, gamma is the distortion coefficient, r1、r2For two elements in the rotation matrix R, t is the translation vector.
In the embodiment of the invention, the calibration barrel is arranged to replace the scanning head as the main equipment for the intraoral scanner to carry out the calibration process, so that the problem of multiple times of calibration caused by the situation that the scanning head is replaced at any time in the intraoral scanner can be solved, the operation workload of the system is greatly reduced, and the calibration cost is saved; two groups of image data displayed by the calibration plate under two different light paths are collected by the scanning head, and all the image data are directly analyzed by utilizing a homography conversion algorithm, so that the calibration process of the intraoral scanner is simpler and faster.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a method for calibrating an intraoral scanner in an embodiment of the present invention;
FIG. 2 is a schematic diagram of a mirror image of each calibration image pair according to an embodiment of the present invention;
fig. 3 is a schematic structural component diagram of an intraoral scanner calibration device in an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Examples
Referring to fig. 1, fig. 1 is a schematic flow chart illustrating a calibration method of an intra-oral scanner according to an embodiment of the present invention.
As shown in fig. 1, a calibration method of an intraoral scanner includes the following steps:
s101, based on a deflectable calibration plate arranged in a calibration cylinder, acquiring two groups of image data of the calibration plate under two different light paths by using a scanning head;
in an embodiment of the present invention, an adjustment buckle is disposed on the calibration cylinder, and the adjustment buckle is controlled by an operating system of an intraoral scanner, and is configured to sequentially adjust a deflection angle of the calibration plate according to a set rule, and when the calibration plate is adjusted according to the set rule, a spatial position corresponding to image data acquired by the scanning head at a current angle is increased to a specific displacement compared with a spatial position corresponding to image data acquired at a previous angle, where the specific displacement is set to be 1.25mm in the embodiment of the present invention.
Specifically, with an angle of 0 ° between the plane of the calibration plate and the optical axis as a starting point, the operating system controls the adjustment buckle to rotate in place each time, which indicates that the difference between the deflection angle between the plane of the current calibration plate and the optical axis is 90 ° compared with the deflection angle between the plane of the calibration plate and the optical axis when the current calibration plate is adjusted at the last time, and therefore a set of image data presented by the calibration plate under any one optical path can be sequentially acquired, including: the image processing apparatus includes image data 1 when a deflection angle between the plane of the calibration plate and the optical axis is 0 °, image data 2 when a deflection angle between the plane of the calibration plate and the optical axis is 90 °, image data 3 when a deflection angle between the plane of the calibration plate and the optical axis is 180 °, image data 4 when a deflection angle between the plane of the calibration plate and the optical axis is 270 °, image data 5 when a deflection angle between the plane of the calibration plate and the optical axis is 360 °, image data 6 when a deflection angle between the plane of the calibration plate and the optical axis is 450 °, image data 7 when a deflection angle between the plane of the calibration plate and the optical axis is 540 °, and image data 8 when a deflection angle between the plane of the calibration plate and the optical axis is 630 °.
S102, dividing the two groups of image data into a plurality of pairs of calibration image pairs by taking the same deflection angle as a combination basis, wherein two calibration images contained in each pair of calibration image pairs are in a mirror image relationship with each other;
in the embodiment of the present invention, each group of image data includes eight image data corresponding to the calibration plate under eight different deflection angles, and the eight pairs of calibration image pairs can be obtained by dividing the calibration plate according to the same deflection angle.
S103, extracting a plurality of pairs of matching point pairs from each pair of calibration image pairs, and solving a relevant homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs;
the implementation process of the invention comprises the following steps:
(1) according to the schematic diagram of the mirror image in each pair of calibration image pairs shown in FIG. 2, the pixel coordinates corresponding to the matching point pair of the ith (i is more than or equal to 1 and less than or equal to 4) pair are obtained and are respectively Pi(xi，yi)、P′i(x′i,y′i)；
(2) Determining PiPoint and P'iThe relationship between points is:
(3) converting the relation to obtain:
(4) since the homography H is a homogeneous matrix (illustrating the last element H of the homography H33In fact, the value of normalization is 1), and the homography matrix H is rewritten into a vector expression mode as follows: h ═ H (H)11,H12,H13,H21,H22,H23,H31,H32,1)TFurther, the above multivariate equation set is rewritten as:
(5) and i is set as i +1 and the steps are circularly executed until four groups of constant vectors associated with four pairs of matching point pairs are obtained, and the four groups of constant vectors are combined to form a constant matrix
All matrix elements contained in vector H (i.e., H) are solved using the relationship Ah ═ 011～H32These eight element values) to obtain the homography matrix H associated with the current calibration image pair. It should be noted that, in the embodiment of the present invention, only four pairs of matching point pairs are used to solve the homography matrix H, which is set according to the fact that the homography matrix H actually includes eight unknown quantities, and no specific limitation is made on the selection of the four pairs of matching point pairs, so that only two points included in any pair of matching point pairs need to be ensured to have a mirror symmetry relationship.
And S104, performing fusion calculation by combining the plurality of homography matrixes obtained by solving to obtain all internal and external parameters of the intraoral scanner.
In the embodiment of the present invention, eight homography matrices H associated with eight pairs of calibration images can be obtained by performing the above step S103 in a cyclic manner, at this time, eight equation equations can be listed by using the relationship between each homography matrix H and all internal and external parameters of the intraoral scanner, and finally, the eight equation equations are decomposed by using a direct linear transformation solution to obtain the optimal solutions of all internal and external parameters; wherein the relationship between each homography matrix and all internal and external parameters of the intraoral scanner is as follows:
in the formula: s is a scale factor, (u)0,v0) Is the coordinate of the projection point, f, presented when the center of the optical axis is projected to the imaging plane along the direction of the z-axisxIs the physical size, f, of any pixel point in the x-axis directionyIs the physical size of any pixel point in the y-axis direction, gamma is the distortion coefficient, r1、r2For two elements in the rotation matrix R, t is the translation vector.
In the embodiment of the invention, the calibration barrel is arranged to replace the scanning head as the main equipment for the intraoral scanner to carry out the calibration process, so that the problem of multiple times of calibration caused by the situation that the scanning head is replaced at any time in the intraoral scanner can be solved, the operation workload of the system is greatly reduced, and the calibration cost is saved; two groups of image data displayed by the calibration plate under two different light paths are collected by the scanning head, and all the image data are directly analyzed by utilizing a homography conversion algorithm, so that the calibration process of the intraoral scanner is simpler and faster.
Examples
Referring to fig. 3, fig. 3 is a schematic structural diagram of an intra-oral scanner calibration apparatus according to an embodiment of the present invention.
As shown in fig. 3, an intraoral scanner calibration apparatus includes the following:
the image acquisition module 201 is used for acquiring two groups of image data of the calibration plate under two different light paths by using a scanning head based on a deflectable calibration plate arranged in the calibration cylinder;
in an embodiment of the present invention, an adjustment buckle is disposed on the calibration cylinder, and the adjustment buckle is controlled by an operating system of an intraoral scanner, and is configured to sequentially adjust a deflection angle of the calibration plate according to a set rule, and when the calibration plate is adjusted according to the set rule, a spatial position corresponding to image data acquired by the scanning head at a current angle is increased to a specific displacement compared with a spatial position corresponding to image data acquired at a previous angle, where the specific displacement is set to be 1.25mm in the embodiment of the present invention.
Specifically, with an angle of 0 ° between the plane of the calibration plate and the optical axis as a starting point, the operating system controls the adjustment buckle to rotate in place each time, which indicates that the difference between the deflection angle between the plane of the current calibration plate and the optical axis is 90 ° compared with the deflection angle between the plane of the calibration plate and the optical axis when the current calibration plate is adjusted at the last time, and therefore a set of image data presented by the calibration plate under any one optical path can be sequentially acquired, including: the image processing apparatus includes image data 1 when a deflection angle between the plane of the calibration plate and the optical axis is 0 °, image data 2 when a deflection angle between the plane of the calibration plate and the optical axis is 90 °, image data 3 when a deflection angle between the plane of the calibration plate and the optical axis is 180 °, image data 4 when a deflection angle between the plane of the calibration plate and the optical axis is 270 °, image data 5 when a deflection angle between the plane of the calibration plate and the optical axis is 360 °, image data 6 when a deflection angle between the plane of the calibration plate and the optical axis is 450 °, image data 7 when a deflection angle between the plane of the calibration plate and the optical axis is 540 °, and image data 8 when a deflection angle between the plane of the calibration plate and the optical axis is 630 °.
The image dividing module 202 is configured to divide the two sets of image data into a plurality of pairs of calibration image pairs based on the same deflection angle, where two calibration images included in each pair of calibration image pairs are in a mirror relationship with each other;
in the embodiment of the present invention, each group of image data includes eight image data corresponding to the calibration plate under eight different deflection angles, and the eight pairs of calibration image pairs can be obtained by dividing the calibration plate according to the same deflection angle.
The matrix solving module 203 is configured to extract a plurality of pairs of matching point pairs from each pair of calibration image pairs, and solve a corresponding homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs;
the implementation process of the invention comprises the following steps:
(1) according to the schematic diagram of the mirror image in each pair of calibration image pairs shown in FIG. 2, the pixel coordinates corresponding to the matching point pair of the ith (i is more than or equal to 1 and less than or equal to 4) pair are obtained and are respectively Pi(xi,yi)、P′i(x′i,y′i)；
(2) Determining PiPoint and P'iThe relationship between points is:
(3) converting the relation to obtain:
(4) since the homography H is a homogeneous matrix (illustrating the last element H of the homography H33In fact, the value of normalization is 1), and the homography matrix H is rewritten into a vector expression mode as follows: h ═ H (H)11,H12,H13,H21,H22,H23,H31,H32,1)TFurther, the above multivariate equation set is rewritten as:
(5) and i is set as i +1 and the steps are circularly executed until four groups of constant vectors associated with four pairs of matching point pairs are obtained, and the four groups of constant vectors are combined to form a constant matrix
All matrix elements contained in vector H (i.e., H) are solved using the relationship Ah ═ 011～H32These eight element values) to obtain the homography matrix H associated with the current calibration image pair. It should be noted that, in the embodiment of the present invention, only four pairs of matching point pairs are used to solve the homography matrix H, which is set according to the fact that the homography matrix H actually includes eight unknown quantities, and no specific limitation is made on the selection of the four pairs of matching point pairs, so that only two points included in any pair of matching point pairs need to be ensured to have a mirror symmetry relationship.
And the parameter acquisition module 204 is configured to perform fusion calculation by combining the plurality of homography matrices obtained through solution to obtain all internal and external parameters of the intraoral scanner.
In the embodiment of the present invention, eight homography matrices H associated with eight pairs of calibration image pairs can be obtained through the internal cyclic execution of the matrix solving module 203, at this time, eight equation equations can be listed by using the relationship between each homography matrix H and all internal and external parameters of the intraoral scanner, and finally, the eight equation equations are decomposed and operated by using a direct linear transformation solution to obtain the optimal solutions of all internal and external parameters; wherein the relationship between each homography matrix and all internal and external parameters of the intraoral scanner is as follows:
in the formula: s is a scale factor, (u)0,v0) Is the coordinate of the projection point, f, presented when the center of the optical axis is projected to the imaging plane along the direction of the z-axisxIs the physical size, f, of any pixel point in the x-axis directionyIs the physical size of any pixel point in the y-axis direction, gamma is the distortion coefficient, r1、r2For two elements in the rotation matrix R, t is the translation vector.
In the embodiment of the invention, the calibration barrel is arranged to replace the scanning head as the main equipment for the intraoral scanner to carry out the calibration process, so that the problem of multiple times of calibration caused by the situation that the scanning head is replaced at any time in the intraoral scanner can be solved, the operation workload of the system is greatly reduced, and the calibration cost is saved; two groups of image data displayed by the calibration plate under two different light paths are collected by the scanning head, and all the image data are directly analyzed by utilizing a homography conversion algorithm, so that the calibration process of the intraoral scanner is simpler and faster.
Those skilled in the art will appreciate that all or part of the steps in the methods of the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer-readable storage medium, and the storage medium may include: read Only Memory (ROM), Random Access Memory (RAM), magnetic or optical disks, and the like.
The method and the device for calibrating an intraoral scanner provided by the embodiment of the present invention are described in detail, and the specific examples are used herein to explain the principle and the embodiment of the present invention, and the description of the embodiments is only used to help understand the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (10)
1. An intraoral scanner calibration method, the method comprising:
based on a deflectable calibration plate arranged in a calibration cylinder, two groups of image data displayed by the calibration plate under two different light paths are collected by a scanning head;
dividing the two groups of image data into a plurality of pairs of calibration image pairs by taking the same deflection angle as a combination basis, wherein two calibration images contained in each pair of calibration image pairs are in a mirror image relationship with each other;
extracting a plurality of pairs of matching point pairs from each pair of calibration image pairs, and solving a relevant homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs;
and performing fusion calculation by combining the plurality of homography matrixes obtained by solving to obtain all internal and external parameters of the intraoral scanner.
2. The calibration method for the intraoral scanner according to claim 1, wherein an adjustment buckle is arranged on the calibration cylinder, and the adjustment buckle is controlled by an operating system of the intraoral scanner and is used for orderly adjusting the deflection angle of the calibration plate according to a set rule.
3. An intra-oral scanner calibration method according to claim 2, wherein when the calibration plate is adjusted in deflection angle according to a set rule, the spatial position corresponding to the image data acquired by the scanner head at the current angle is raised to a specific displacement compared to the spatial position corresponding to the image data acquired at the previous angle.
4. The intraoral scanner calibration method according to claim 1, wherein the extracting pairs of matching point pairs from each pair of calibration images and solving the associated homography matrix according to the pixel coordinates corresponding to the pairs of matching point pairs comprises:
obtaining the pixel coordinates corresponding to the ith (i is more than or equal to 1 and less than or equal to 4) pair of matching points as Pi(xi,yi)、P′i(x′i,y′i)；
Determining PiPoint and P'iThe relationship between points is:
converting the relation to obtain:
because the homography matrix H is a homogeneous matrix, the homography matrix H is rewritten into a vector expression mode as follows: h ═ H (H)11,H12,H13,H21,H22，H23,H31,H32,1)TFurther, the above multivariate equation set is rewritten as:
and (3) enabling i to be i +1, and executing the steps in a circulating manner until four groups of constant vectors associated with the four pairs of matching points are obtained, combining the four groups of constant vectors to form a constant matrix A, solving all matrix elements contained in the vector H by using a relational expression Ah to be 0, and further obtaining a homography matrix H associated with the current calibration image pair.
5. An intraoral scanner calibration method according to claim 1, characterized in that the relation between each homography matrix and all internal and external parameters of the intraoral scanner is:
wherein s is a scale factor and (u)0,v0) Is the coordinate of the projection point, f, presented when the center of the optical axis is projected to the imaging plane along the direction of the z-axisxIs the physical size, f, of any pixel point in the x-axis directionyIs the physical size of any pixel point in the y-axis direction, gamma is the distortion coefficient, r1、r2For two elements in the rotation matrix R, t is the translation vector.
6. An intraoral scanner calibration apparatus, the apparatus comprising:
the image acquisition module is used for acquiring two groups of image data of the calibration plate under two different light paths by utilizing the scanning head based on the fact that the calibration plate which can deflect is arranged in the calibration cylinder;
the image dividing module is used for dividing the two groups of image data into a plurality of pairs of calibration image pairs by taking the same deflection angle as a combination basis, and two calibration images contained in each pair of calibration image pairs are in a mirror image relationship with each other;
the matrix solving module is used for extracting a plurality of pairs of matching point pairs from each pair of calibration image pairs and solving a relevant homography matrix according to pixel coordinates corresponding to the plurality of pairs of matching point pairs;
and the parameter acquisition module is used for carrying out fusion calculation by combining the plurality of homography matrixes obtained by solving to obtain all internal and external parameters of the intraoral scanner.
7. An intraoral scanner calibration device according to claim 6, wherein the calibration cylinder is provided with an adjustment buckle, the adjustment buckle is controlled by an operating system of the intraoral scanner, and is used for orderly adjusting the deflection angle of the calibration plate according to a set rule.
8. An intra-oral scanner calibration apparatus according to claim 7, wherein when the calibration plate is adjusted in terms of the deflection angle according to the set rule, the spatial position corresponding to the image data acquired by the scanner head at the current angle is raised to a specific displacement compared to the spatial position corresponding to the image data acquired at the previous angle.
9. An intraoral scanner calibration apparatus according to claim 6, wherein the matrix solving module is further configured to obtain pixel coordinates P corresponding to the ith (1 ≦ i ≦ 4) pair of matching pointsi(xi,yi)、P′i(x′i,y′i)；
Determining PiPoint and P'iThe relationship between points is:
converting the relation to obtain:
because the homography matrix H is a homogeneous matrix, the homography matrix H is rewritten into a vector expression mode as follows: h ═ H (H)11,H12,H13,H21,H22,H23,H31,H32，1)TFurther, the above multivariate equation set is rewritten as:
and (3) enabling i to be i +1, and executing the steps in a circulating manner until four groups of constant vectors associated with the four pairs of matching points are obtained, combining the four groups of constant vectors to form a constant matrix A, solving all matrix elements contained in the vector H by using a relational expression Ah to be 0, and further obtaining a homography matrix H associated with the current calibration image pair.
10. An intraoral scanner calibration apparatus according to claim 6, wherein the relationship between each homography matrix and all internal and external parameters of the intraoral scanner is:
wherein s is a scale factor and (u)0,v0) Is the coordinate of the projection point, f, presented when the center of the optical axis is projected to the imaging plane along the direction of the z-axisxIs the physical size, f, of any pixel point in the x-axis directionyIs the physical size of any pixel point in the y-axis direction, gamma is the distortion coefficient, r1、r2For two elements in the rotation matrix R, t is the translation vector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110494766.XA CN113177989A (en) | 2021-05-07 | 2021-05-07 | Intraoral scanner calibration method and device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110494766.XA CN113177989A (en) | 2021-05-07 | 2021-05-07 | Intraoral scanner calibration method and device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113177989A true CN113177989A (en) | 2021-07-27 |
Family
ID=76928429
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110494766.XA Pending CN113177989A (en) | 2021-05-07 | 2021-05-07 | Intraoral scanner calibration method and device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113177989A (en) |
Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104835115A (en) * | 2015-05-07 | 2015-08-12 | 中国科学院长春光学精密机械与物理研究所 | Imaging method for aerial camera, and system thereof |
| CN105157602A (en) * | 2015-07-13 | 2015-12-16 | 西北农林科技大学 | Remote three-dimensional scanning system and method based on machine vision |
| US20160140713A1 (en) * | 2013-07-02 | 2016-05-19 | Guy Martin | System and method for imaging device modelling and calibration |
| CN105654502A (en) * | 2016-03-30 | 2016-06-08 | 广州市盛光微电子有限公司 | Panorama camera calibration device and method based on multiple lenses and multiple sensors |
| CN106097348A (en) * | 2016-06-13 | 2016-11-09 | 大连理工大学 | A kind of three-dimensional laser point cloud and the fusion method of two dimensional image |
| US20160379077A1 (en) * | 2015-06-29 | 2016-12-29 | International Business Machines Corporation | Pose detection using depth camera |
| CN107067441A (en) * | 2017-04-01 | 2017-08-18 | 海信集团有限公司 | Camera marking method and device |
| CN110517325A (en) * | 2019-08-29 | 2019-11-29 | 的卢技术有限公司 | The vehicle body surrounding objects localization method and system of a kind of coordinate transform and coordinate transform |
| CN111179358A (en) * | 2019-12-30 | 2020-05-19 | 浙江商汤科技开发有限公司 | Calibration method, device, equipment and storage medium |
| CN111462246A (en) * | 2020-03-09 | 2020-07-28 | 浙江未来技术研究院(嘉兴) | Equipment calibration method of structured light measurement system |
| CN111536902A (en) * | 2020-04-22 | 2020-08-14 | 西安交通大学 | Galvanometer scanning system calibration method based on double checkerboards |
-
2021
- 2021-05-07 CN CN202110494766.XA patent/CN113177989A/en active Pending
Patent Citations (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160140713A1 (en) * | 2013-07-02 | 2016-05-19 | Guy Martin | System and method for imaging device modelling and calibration |
| CN104835115A (en) * | 2015-05-07 | 2015-08-12 | 中国科学院长春光学精密机械与物理研究所 | Imaging method for aerial camera, and system thereof |
| US20160379077A1 (en) * | 2015-06-29 | 2016-12-29 | International Business Machines Corporation | Pose detection using depth camera |
| CN105157602A (en) * | 2015-07-13 | 2015-12-16 | 西北农林科技大学 | Remote three-dimensional scanning system and method based on machine vision |
| CN105654502A (en) * | 2016-03-30 | 2016-06-08 | 广州市盛光微电子有限公司 | Panorama camera calibration device and method based on multiple lenses and multiple sensors |
| CN106097348A (en) * | 2016-06-13 | 2016-11-09 | 大连理工大学 | A kind of three-dimensional laser point cloud and the fusion method of two dimensional image |
| CN107067441A (en) * | 2017-04-01 | 2017-08-18 | 海信集团有限公司 | Camera marking method and device |
| CN110517325A (en) * | 2019-08-29 | 2019-11-29 | 的卢技术有限公司 | The vehicle body surrounding objects localization method and system of a kind of coordinate transform and coordinate transform |
| CN111179358A (en) * | 2019-12-30 | 2020-05-19 | 浙江商汤科技开发有限公司 | Calibration method, device, equipment and storage medium |
| CN111462246A (en) * | 2020-03-09 | 2020-07-28 | 浙江未来技术研究院(嘉兴) | Equipment calibration method of structured light measurement system |
| CN111536902A (en) * | 2020-04-22 | 2020-08-14 | 西安交通大学 | Galvanometer scanning system calibration method based on double checkerboards |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US20220076391A1 (en) | Image Distortion Correction Method and Apparatus | |
| WO2018019282A1 (en) | Binocular panorama image obtaining method and apparatus, and storage medium | |
| EP2785045B1 (en) | Image processing apparatus and method, and image capturing apparatus | |
| JP5558973B2 (en) | Image correction apparatus, correction image generation method, correction table generation apparatus, correction table generation method, correction table generation program, and correction image generation program | |
| WO2012039043A1 (en) | Stereo image generating unit, method of generating stereo image, and stereo image generating computer program | |
| US11403739B2 (en) | Methods and apparatus for retargeting and prioritized interpolation of lens profiles | |
| CN111199528A (en) | Fisheye image distortion correction method | |
| US9652847B2 (en) | Method for calibrating a digital optical imaging system having a zoom system, method for correcting aberrations in a digital optical imaging system having a zoom system, and digital optical imaging system | |
| JP2012249070A (en) | Imaging apparatus and imaging method | |
| CN112070845A (en) | Calibration method and device of binocular camera and terminal equipment | |
| CN111340737B (en) | Image correction method, device and electronic system | |
| CN113686262B (en) | Line structure optical scanner calibration method and device and storage medium | |
| WO2014002521A1 (en) | Image processing device and image processing method | |
| JP2015015587A (en) | Imaging device, and method of controlling the same | |
| CN112470192A (en) | Dual-camera calibration method, electronic device and computer-readable storage medium | |
| CN109584312A (en) | Camera calibration method, device, electronic equipment and computer readable storage medium | |
| CN112258581B (en) | On-site calibration method for panoramic camera with multiple fish glasses heads | |
| CN107492080B (en) | Calibration-free convenient monocular head image radial distortion correction method | |
| WO2016098323A1 (en) | Information processing device, information processing method, and recording medium | |
| CN111292380B (en) | Image processing method and device | |
| CN109990756B (en) | Binocular ranging method and system | |
| CN101729739A (en) | Method for rectifying deviation of image | |
| CN109785225B (en) | Method and device for correcting image | |
| CN113177989A (en) | Intraoral scanner calibration method and device | |
| JP2006010613A (en) | Correcting method of image distortion |
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 |