CN113379846B - Method for calibrating rotating shaft of rotary table based on direction indication mark point calibration template - Google Patents
Method for calibrating rotating shaft of rotary table based on direction indication mark point calibration template Download PDFInfo
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- CN113379846B CN113379846B CN202110591203.2A CN202110591203A CN113379846B CN 113379846 B CN113379846 B CN 113379846B CN 202110591203 A CN202110591203 A CN 202110591203A CN 113379846 B CN113379846 B CN 113379846B
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- 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
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/60—Analysis of geometric attributes
- G06T7/62—Analysis of geometric attributes of area, perimeter, diameter or volume
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- 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
- G06T2207/10—Image acquisition modality
- G06T2207/10004—Still image; Photographic image
- G06T2207/10012—Stereo images
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Abstract
The invention relates to the technical field of image processing and pattern recognition, and discloses a method for calibrating a rotating shaft of a rotary table based on a direction indication mark point calibration template, which comprises the following steps: shooting a multi-angle image; extracting a matrix; constructing a calibration template coordinate system; resolving a camera coordinate system; fitting the circle center of the rotary table; fitting a turntable plane; constructing a coordinate system of the rotary table; a transformation matrix is calculated. The invention can finish the calibration of the rotary table rotary shaft by using a simple calibration template.
Description
Technical Field
The invention relates to the technical field of image processing and pattern recognition, in particular to a method for calibrating a rotary table rotating shaft based on a direction indication mark point calibration template.
Background
Modelling object shots by means of cameras, whether line laser cameras or area laser cameras, by means of
And combining the data of all angles of the scanned object to complete three-dimensional modeling. The object is rotated on the turntable, and the data of all angles are combined into three-dimensional data. The calibration of the rotating shaft of the rotary table is particularly important in the image recognition modeling process.
The existing turntable rotating shaft calibration process is realized by standard three-dimensional objects such as a cube, a sphere and a cylinder, the standard three-dimensional objects are rotated on a turntable and scanned by a camera, and an image after modeling is compared with the standard image and analyzed. The standard three-dimensional object needs to measure errors regularly, and has the defects of complex operation, large calculation amount and easy deviation, thereby causing identification errors.
Disclosure of Invention
The invention aims to solve the problems and provides a turntable rotating shaft calibration method based on a direction indication mark point calibration template, which can finish the calibration of the turntable rotating shaft by using a simple calibration template.
The technical scheme adopted by the invention is as follows:
a method for calibrating a rotating shaft of a rotary table based on a direction indicating mark point calibration template is characterized by comprising the following steps: the method for calibrating the rotating shaft of the rotary table comprises the following steps of:
(1) placing the calibration template in the central area of the rotary table;
(2) presetting the time interval between the rotating speed of the turntable and the time interval of camera acquisition;
(3) starting the rotary table to rotate for 360 degrees to obtain an image sequence of a calibration template acquired by the camera;
(4) extracting a mark point matrix in each calibration template image;
(5) extracting direction mark points in each calibration template image;
(6) determining the central point of the mark point matrix in each calibration template image;
(7) determining the X-axis direction and the Y-axis direction of each calibration template coordinate system according to the central mark point and the direction mark point;
(8) identifying the calibration template according to the constructed calibration template coordinate system and the central marker point to obtain object point coordinates of the marker point;
(9) resolving and acquiring the camera attitude of the position of each calibration template image according to the pixel coordinates and the object point coordinates of the mark points;
(10) calculating the three-dimensional coordinates of the mark points under the camera coordinate system according to the camera attitude and the pixel coordinates of the mark points;
(11) matching the mark point matrixes in all the calibration template images according to the object point coordinates of the mark points;
(12) calculating the circle center of a circle formed by rotating the matched mark points in all the images for 360 degrees through circle fitting;
(13) searching an optimal solution from a plurality of centers of circles by using a MeanShift algorithm to obtain a rotation center of the turntable;
(14) fitting the turntable plane by using all the mark point matrixes three-dimensional points;
(15) constructing a turntable coordinate system by using the rotation center and the normal of the turntable plane;
(16) and calculating to obtain a transformation matrix transformed from the camera coordinate system to the turntable coordinate system.
Further, in the step (7), the X-axis direction of the calibration template coordinate system is determined by the left-hand rule.
Further, the mark point matrix is an odd-numbered row-column matrix, and the central point in the step (6) is a central mark point of the mark point matrix.
The invention has the beneficial effects that:
(1) the flat calibration template is applied, so that the use and the replacement are easier;
(2) the calculation precision is high, and the identification stability is high.
Drawings
FIG. 1 is a schematic plan view of a calibration template;
FIG. 2 is a schematic view of the position of the camera system and the turntable;
FIG. 3 is a flow diagram of the present invention;
FIG. 4 is the object point coordinates of the index points in the calibration template plane coordinate system.
Detailed Description
The following describes in detail a specific embodiment of the method for calibrating a rotating shaft of a turntable based on a direction indication mark point calibration template in accordance with the present invention with reference to the accompanying drawings.
Referring to fig. 1, the calibration template includes a landmark matrix and a direction indicating landmark outside the landmark matrix, and the direction indicating landmark is located on a perpendicular bisector of a rectangular side of the landmark matrix.
Referring to fig. 2, the calibration template is placed on the turntable 1, and the calibration template at different rotation positions on the turntable 1 is photographed by the camera system 2 when the turntable 1 rotates.
Referring to fig. 3, the steps of the method for calibrating the rotating shaft of the turntable are as follows:
1. and placing the calibration template in the middle area of the rotary table.
2. The time interval between the rotating speed of the rotary table and the acquisition of the camera is input.
3. And starting the rotary table to rotate for 360 degrees to obtain an image sequence acquired by the camera.
4. And extracting a mark point matrix in the calibration template image.
5. The direction mark points in the calibration template image are detected.
6. Detecting a central mark point in the mark point matrix, wherein the rows and the columns of the general mark point matrix are odd numbers, and the central mark point is the most middle mark point in the mark point matrix.
7. Determining the X-axis direction of the calibration template coordinate system according to the central mark point and the direction mark point
8. And determining the Y-axis direction of the coordinate system of the calibration template according to the left-hand rule.
9. And identifying the calibration template according to the constructed calibration template coordinate system and the central mark point to obtain the object point coordinates of the mark point (see figure 4).
10. And resolving the camera attitude when each calibration template image is acquired according to the pixel coordinates and the object point coordinates of the mark points.
11. And calculating the three-dimensional coordinates of the mark points in the camera coordinate system according to the camera attitude and the pixel coordinates of the mark points.
12. And matching the mark point matrixes in all the calibration template images according to the object point coordinates.
13. And calculating the circle center of the circle formed by rotating the matched mark points in all the images for 360 degrees through circle fitting.
14. And finding the optimal rotation center of the turntable from a plurality of circular centers by using a MeanShift algorithm. The MeanShift algorithm is a hill-climbing algorithm based on kernel density estimation, and can be used for clustering, image segmentation, tracking and the like. See the chinese patents: cn201711318892.x, a visual tracking algorithm improved based on the MeanShift principle.
15. And fitting the three-dimensional points of the matrix of all the mark points to the plane of the turntable.
16. The turntable coordinate system is constructed with the rotation center and the normal to the turntable plane.
17. A transformation matrix is calculated for transforming from the camera coordinate system to the turret coordinate system.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (3)
1. A method for calibrating a rotating shaft of a rotary table based on a direction indicating mark point calibration template is characterized by comprising the following steps: the method for calibrating the rotating shaft of the rotary table comprises the following steps of:
firstly, placing the calibration template in the central area of a turntable;
step two, presetting the time interval between the rotating speed of the rotary table and the time interval of camera acquisition;
step three, starting the rotary table to rotate for 360 degrees to obtain an image sequence of the calibration template acquired by the camera;
extracting a mark point matrix in each calibration template image;
step five, extracting direction mark points in each calibration template image;
sixthly, determining the central point of the mark point matrix in each calibration template image;
step seven, determining the X-axis direction and the Y-axis direction of each calibration template coordinate system according to the central mark point and the direction mark point;
identifying the calibration template according to the constructed calibration template coordinate system and the central marker point to obtain object point coordinates of the marker point;
calculating and acquiring the camera attitude of each calibration template image at the position according to the pixel coordinates and the object point coordinates of the mark points;
step ten, calculating the three-dimensional coordinates of the mark points under the camera coordinate system according to the camera attitude and the pixel coordinates of the mark points;
step eleven, matching the mark point matrixes in all the calibration template images according to the object point coordinates of the mark points;
step twelve, calculating the circle center of the circle formed by rotating the matched mark points in all the images for 360 degrees through circle fitting;
step thirteen, searching an optimal solution from a plurality of centers of circles by adopting a MeanShift algorithm to obtain a rotation center of the turntable;
fourteen, fitting a turntable plane by using all the mark point matrix three-dimensional points;
fifthly, constructing a turntable coordinate system by using the rotation center and the normal of the turntable plane;
sixthly, calculating to obtain a transformation matrix transformed from the camera coordinate system to the turntable coordinate system.
2. The method for calibrating a rotating shaft of a rotary table based on the direction indicating mark point calibration template according to claim 1, wherein: and seventhly, determining the X-axis direction of the calibration template coordinate system by a left-hand rule.
3. The method for calibrating a rotating shaft of a rotary table based on the direction indicating mark point calibration template according to claim 1, wherein: the mark point matrix is an odd-number row-column matrix, and the central point in the sixth step is a central mark point of the mark point matrix.
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Denomination of invention: A Method for Calibrating the Rotating Axis of a Turntable Based on the Calibration Template of Direction Indication Marker Points Effective date of registration: 20230817 Granted publication date: 20220809 Pledgee: Bank of Communications Ltd. Shanghai Minhang branch Pledgor: SHANGHAI X-IMAGING INFO. & TECH. Co.,Ltd. Registration number: Y2023310000474 |
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