CN108895959A - A kind of camera calibration plate angle point calculating method based on sub-pix - Google Patents

A kind of camera calibration plate angle point calculating method based on sub-pix Download PDF

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CN108895959A
CN108895959A CN201810388946.8A CN201810388946A CN108895959A CN 108895959 A CN108895959 A CN 108895959A CN 201810388946 A CN201810388946 A CN 201810388946A CN 108895959 A CN108895959 A CN 108895959A
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sub
pix
point
pixel
angle point
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CN108895959B (en
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肖峻
邓荣钰
陈祥
刘三亚
张静
刘娟秀
倪光明
杜晓辉
郝如茜
刘霖
刘永
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University of Electronic Science and Technology of China
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/10—Segmentation; Edge detection
    • G06T7/13—Edge detection
    • 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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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Theoretical Computer Science (AREA)
  • Image Analysis (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The invention discloses a kind of camera calibration plate angle point calculating method based on sub-pix, the invention belongs to digital image processing field, the angular-point detection method being related in the calibration of one-touch measuring instrument, especially for the camera calibration angular-point detection method based on sub-pix.For based on the Corner character inaccuracy in plane template scaling method, lead to the disadvantages of larger to the error of actual object dimensional measurement, the subpixel method before the sub-pix Corner Detection replacement based on gray value model that the present invention provides a kind of greatly improves the detection accuracy of the accuracy and object of corner location.Be shown experimentally that the Sub-pixel Edge Detection based on gray value model can be by the internal ratio of 0.1 pixel of precision controlling of angle point and other sub-pix angular-point detection method precision are all in 0.2 pixel or so.It is doubled than other sub-pix angular-point detection method precision.

Description

A kind of camera calibration plate angle point calculating method based on sub-pix
Technical field
The invention belongs to digital image processing field, the angular-point detection method being related in the calibration of one-touch measuring instrument is special It is not for the camera calibration angular-point detection method based on sub-pix.
Technical background
It is higher and higher to Product Precision measurement request with the development of industry, the size of object is accurately measured to accurate electricity Son manufacture, precision machinery manufacture play an important role.And demarcate accuracy the measurement of final workpiece is played it is decisive Effect.In scaling method based on plane template, the Corner Detection Algorithm of image grayscale is only able to detect the Pixel-level of angle point Coordinate, the other Corner Detection of sub-pixel before assume that gradient vector is fixed, lead to the angle point of sub-pixel positioning It is inaccurate.There is the linear edge that the slope of a standard is 1/2 in the ideal image of one width, and the straight line is also cross certain The lower left corner of a pixel to the upper right corner of adjacent pixel, the grey scale pixel value of black portions is A, the pixel of white portion in left figure Gray value is B, and accounting coefficient is according to area by pixel value C, the D on two sides of left and right：
Assuming that mask is
Wherein α is to emphasize that then the gray value in such as figure attached drawing 1 is that the local derviation in the grid of C indicates for the weight of intermediate row/column It is as follows：
To learn that the localization method of its sub-pix is inaccurate.
Summary of the invention
For based on the Corner character inaccuracy in plane template scaling method, lead to the mistake to actual object dimensional measurement The disadvantages of difference is larger, the sub-pix side before the sub-pix Corner Detection replacement based on gray value model that the present invention provides a kind of Method greatly improves the accuracy of corner location and the detection accuracy of object.
Technical solution of the present invention is a kind of camera calibration plate angle point calculating method based on sub-pix, and this method includes：
Step 1：Obtain the image of scaling board；
Step 2：Denoising is filtered to image is obtained；
Step 3：The angle point of each chessboard block of scaling board is calculated using Harris angular-point detection method；
Step 4：The sub-pix angle point for determining each angle point, is calculated as follows for each angle point；
Step 4.1：A big rectangular image is intercepted out from the image that step 2 obtains centered on angle point, big rectangle Length is between 70% to the 80% of entire gridiron pattern pixel wide；
Step 4.2：Mean filter is carried out to the big rectangular image intercepted out, calculates the vertical direction and water of each pixel Square upward gradient calculates the horizontal edge point of each chessboard block in big rectangular image according to pre-set Grads threshold；
Step 4.3：Calculate the gray value of each horizontal edge point, which is be up and down pixel flat Equal gray value；
Step 4.4：If horizontal edge is quadratic function y=a+bx+cx2；
Step 4.5：Intercepting out a pixel size for each marginal point is x=3, and the small rectangular image of y=5 calculates Left column S outL, middle column SM, right column SRThe sum of pixel value；
Wherein：
F(i,j)Indicate that image i-th arranges the gray value of j row, h indicates that the width of each pixel, L, M, R are respectively small histogram The left column as in, middle column, right column pixel is in horizontal edge y=a+bx+cx2The area of downside；
Step 4.6：Calculate horizontal edge point function；
Step 4.7：Vertical edge point function is calculated using the identical method of step 4.2~step 4.6, horizontal edge and Vertical edge crosspoint is sub-pix angle point.
Further, in the step 4.5
Further, horizontal edge is fitted into straight line, vertical edge fits straight line, the intersection of two straight lines Point is sub-pix angle point.
It is shown experimentally that the Sub-pixel Edge Detection based on gray value model can be by the precision controlling 0.1 of angle point The internal ratio of a pixel and other sub-pix angular-point detection method precision are all in 0.2 pixel or so.It is examined than other sub-pix angle points Survey method precision is doubled.
Detailed description of the invention
Fig. 1 is the scaling board schematic diagram obtained；
Fig. 2 is that big rectangle schematic diagram is intercepted in scaling board；
Fig. 3 is edge function schematic diagram in small rectangle；
Fig. 4 acquires sub-pix point comparative diagram by the specific embodiment of the invention.
Specific embodiment
Step 1：Scaling board is placed on the objective table of one-touch measuring instrument, carries out shooting in different positions and angle and obtain Take picture such as Fig. 1 of calibration；
Step 2：Gaussian filtering is carried out to captured image, obtains the calibration after the noise in removal image is denoised Image.
Step 3：Harris Corner Detection is carried out to filtered image and obtains the angular coordinate of pixel scale.
Step 4：Use 5 × 3 points around the angular coordinate of the pixel scale extracted as template, according to grayscale image As feature finds the exact position of sub-pix point.
In shown step 4 the specific steps are：
The angular coordinate for the pixel scale that step 4-1 is obtained using step 3 Harris Corner Detection is being parallel to horizontal seat Direction is marked, defines a rectangle, the width of rectangle is that 30 length in pixels are the 80% of gridiron pattern side length.As shown in Figure 2
After rectangle progress mean filter is deducted in the position of step 4-2 record rectangle in original image, each pixel is calculated Derivative vertically and horizontally and the gradient setting Grads threshold for finding out each point, according to find out before come level side The marginal point of horizontal direction is filtered out to derivative information and Grads threshold.
Step 4-3 indicates that the gray value of the column j row of image i-th can then be indicated with the gray value of neighbouring pixel with F (i, j) Calculation formula is：
Step 4-4 (a) is using each pixel dot center screened as origin, it is assumed that ideal edge be quadratic function and Use y=a+bx+cx2Indicate as shown in Figure 3；
B) the sum of the pixel value of left, center, right column in window is indicated with SL, SM and SR.It finds out in the picture and calculates its value.
(the sum of pixel value in left column)
(the sum of middle column pixel value)
(the sum of right-hand column pixel value)
H in formula is the width of each pixel, and L, M and R respectively indicate area of each column pixel on the downside of linear edge, Expression is：
(left column lower edge area)
(middle column lower edge area)
(right column lower edge area)
C) simultaneously, we can be with 3 diagonal pixel values of window come estimated strength A, the value of B；
(intensity that A is estimated with diagonal 3 pixel values of window)
(intensity that B is estimated with diagonal 3 pixel values of window)
By the above expression formula, we can be found out：
It is hereby achieved that each screening the sub-pixel location in a little.
If step 4-5 wants the detection sub-pix point number satisfaction for finding out the sub-pix point progress sub-pix point number come It asks and all sub-pix points is corrected, repeatedly result such as Fig. 4；
The position of the sub-pix point of repeated detection is averaged error all to control within 0.1 pixel.
Step 4-6 carries out the straight line fitting of horizontal direction to the sub-pix point that detected, and is found out with same step perpendicular Histogram to sub-pix point and in the vertical direction carry out straight line fitting, it is assumed that fit in the horizontal direction come straight line side Journey is y=a1+b1X, it is y=a that the linear equation come is fitted on vertical direction2+b2Two equations are formed equation by x
WhereinSo the coordinate of final angle point is

Claims (3)

1. a kind of camera calibration plate angle point calculating method based on sub-pix, this method include：
Step 1：Obtain the image of scaling board；
Step 2：Denoising is filtered to image is obtained；
Step 3：The angle point of each chessboard block of scaling board is calculated using Harris angular-point detection method；
Step 4：The sub-pix angle point for determining each angle point, is calculated as follows for each angle point；
Step 4.1：A big rectangular image, the length of big rectangle are intercepted out from the image that step 2 obtains centered on angle point It is between 70% to the 80% of entire gridiron pattern pixel wide；
Step 4.2：Mean filter is carried out to the big rectangular image intercepted out, calculates vertical direction and the level side of each pixel Upward gradient calculates the horizontal edge point of each chessboard block in big rectangular image according to pre-set Grads threshold；
Step 4.3：The gray value of each horizontal edge point is calculated, which is the average ash for being up and down pixel Angle value；
Step 4.4：If horizontal edge is quadratic function y=a+bx+cx2；
Step 4.5：Intercepting out a pixel size for each marginal point is x=3, and the small rectangular image of y=5 calculates a left side Arrange SL, middle column SM, right column SRThe sum of pixel value；
Wherein：
F(i,j)Indicate that image i-th arranges the gray value of j row, h indicates that the width of each pixel, L, M, R are respectively in small rectangular image Left column, middle column, right column pixel is in horizontal edge y=a+bx+cx2The area of downside；
Step 4.6：Calculate horizontal edge point function；
Step 4.7：Vertical edge point function is calculated using the identical method of step 4.2~step 4.6, horizontal edge and vertical Edge crossing point is sub-pix angle point.
2. a kind of camera calibration plate angle point calculating method based on sub-pix as described in claim 1, it is characterised in that described In step 4.5
3. a kind of camera calibration plate angle point calculating method based on sub-pix as described in claim 1, it is characterised in that additional Horizontal edge fits to straight line, vertical edge fits straight line, and the crosspoint of two straight lines is sub-pix angle point.
CN201810388946.8A 2018-04-27 2018-04-27 Camera calibration plate corner point calculation method based on sub-pixels Active CN108895959B (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109509200A (en) * 2018-12-26 2019-03-22 深圳市繁维医疗科技有限公司 Checkerboard angle point detection process, device and computer readable storage medium based on contours extract
CN110246187A (en) * 2019-05-09 2019-09-17 深圳市森国科科技股份有限公司 A kind of camera internal reference scaling method, device, equipment and readable storage medium storing program for executing
CN112629407A (en) * 2020-11-24 2021-04-09 西安理工大学 Deformed steel bar size measuring method based on image analysis
CN113066128A (en) * 2021-04-06 2021-07-02 北京大学 Visual detection and recovery method, device, equipment and medium for self-identification plate
CN113487594A (en) * 2021-07-22 2021-10-08 上海嘉奥信息科技发展有限公司 Sub-pixel angular point detection method, system and medium based on deep learning
CN115802005A (en) * 2022-11-08 2023-03-14 苏州迈创信息技术有限公司 Security monitoring video storage method for residential houses

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103345755A (en) * 2013-07-11 2013-10-09 北京理工大学 Chessboard angular point sub-pixel extraction method based on Harris operator
US20140078260A1 (en) * 2012-09-20 2014-03-20 Brown University Method for generating an array of 3-d points
CN103927750A (en) * 2014-04-18 2014-07-16 上海理工大学 Detection method of checkboard grid image angular point sub pixel
CN104331900A (en) * 2014-11-25 2015-02-04 湖南科技大学 Corner sub-pixel positioning method in CCD (charge coupled device) camera calibration
US20150243030A1 (en) * 2014-02-27 2015-08-27 Lavision Gmbh Method to calibrate an optical array, method to display a periodic calibration pattern and a computer program product
CN105374037A (en) * 2015-11-04 2016-03-02 西安邮电大学 Checkerboard angular point automatic screening method of corner detection
CN106097319A (en) * 2016-06-04 2016-11-09 湖北省基础地理信息中心（湖北省北斗卫星导航应用技术研究院） A kind of black and white gridiron pattern Angular Point Extracting Method for camera calibration
CN106846412A (en) * 2017-01-23 2017-06-13 上海兴芯微电子科技有限公司 A kind of checkerboard angle point detection process and device
CN107633536A (en) * 2017-08-09 2018-01-26 武汉科技大学 A kind of camera calibration method and system based on two-dimensional planar template

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140078260A1 (en) * 2012-09-20 2014-03-20 Brown University Method for generating an array of 3-d points
CN103345755A (en) * 2013-07-11 2013-10-09 北京理工大学 Chessboard angular point sub-pixel extraction method based on Harris operator
US20150243030A1 (en) * 2014-02-27 2015-08-27 Lavision Gmbh Method to calibrate an optical array, method to display a periodic calibration pattern and a computer program product
CN103927750A (en) * 2014-04-18 2014-07-16 上海理工大学 Detection method of checkboard grid image angular point sub pixel
CN104331900A (en) * 2014-11-25 2015-02-04 湖南科技大学 Corner sub-pixel positioning method in CCD (charge coupled device) camera calibration
CN105374037A (en) * 2015-11-04 2016-03-02 西安邮电大学 Checkerboard angular point automatic screening method of corner detection
CN106097319A (en) * 2016-06-04 2016-11-09 湖北省基础地理信息中心（湖北省北斗卫星导航应用技术研究院） A kind of black and white gridiron pattern Angular Point Extracting Method for camera calibration
CN106846412A (en) * 2017-01-23 2017-06-13 上海兴芯微电子科技有限公司 A kind of checkerboard angle point detection process and device
CN107633536A (en) * 2017-08-09 2018-01-26 武汉科技大学 A kind of camera calibration method and system based on two-dimensional planar template

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
OLIVIER FAUGERAS 等: "Self-Calibration of a 1D Projective Camera and Its Application to the Self-calibration of a 2D Projective Camera", 《IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE》 *
刘霖 等: "二维光电影像测量仪系统摄像机标定技术", 《中国科技信息》 *

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109509200A (en) * 2018-12-26 2019-03-22 深圳市繁维医疗科技有限公司 Checkerboard angle point detection process, device and computer readable storage medium based on contours extract
CN109509200B (en) * 2018-12-26 2023-09-29 深圳市繁维医疗科技有限公司 Checkerboard corner detection method based on contour extraction and computer readable storage medium
CN110246187A (en) * 2019-05-09 2019-09-17 深圳市森国科科技股份有限公司 A kind of camera internal reference scaling method, device, equipment and readable storage medium storing program for executing
CN112629407A (en) * 2020-11-24 2021-04-09 西安理工大学 Deformed steel bar size measuring method based on image analysis
CN112629407B (en) * 2020-11-24 2024-03-22 西安理工大学 Deformed steel bar dimension measuring method based on image analysis
CN113066128A (en) * 2021-04-06 2021-07-02 北京大学 Visual detection and recovery method, device, equipment and medium for self-identification plate
CN113066128B (en) * 2021-04-06 2023-08-08 北京大学 Visual detection and recovery method, device, equipment and medium for self-identification marking plate
CN113487594A (en) * 2021-07-22 2021-10-08 上海嘉奥信息科技发展有限公司 Sub-pixel angular point detection method, system and medium based on deep learning
CN113487594B (en) * 2021-07-22 2023-12-01 上海嘉奥信息科技发展有限公司 Sub-pixel corner detection method, system and medium based on deep learning
CN115802005A (en) * 2022-11-08 2023-03-14 苏州迈创信息技术有限公司 Security monitoring video storage method for residential houses
CN115802005B (en) * 2022-11-08 2023-09-19 苏州迈创信息技术有限公司 Security monitoring video storage method for residential building

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