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Sub-pixel based angular point calculation method of camera scaling board

A technology of camera calibration and calculation method, which is applied in calculation, image analysis, image data processing, etc., and can solve the problem of large measurement error

Active Publication Date: 2018-11-27
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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Problems solved by technology

[0009] In view of the inaccurate corner positioning in the calibration method based on the plane template, which leads to large errors in the measurement of the actual object size, the present invention provides a sub-pixel corner detection based on the gray value model to replace the previous sub-pixel method Greatly improve the accuracy of the corner position and the detection accuracy of the object

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  • Sub-pixel based angular point calculation method of camera scaling board
  • Sub-pixel based angular point calculation method of camera scaling board
  • Sub-pixel based angular point calculation method of camera scaling board

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Embodiment Construction

[0042] Step 1: Put the calibration plate on the stage of the one-button measuring instrument, take pictures at different positions and angles to obtain calibration pictures such as figure 1 ;

[0043] Step 2: Gaussian filtering is performed on the captured image to obtain a denoised calibration image obtained by removing noise in the image.

[0044] Step 3: Perform Harris corner detection on the filtered image to obtain pixel-level corner coordinates.

[0045] Step 4: Use the 5×3 points around the extracted pixel-level corner point coordinates as a template, and find the precise position of the sub-pixel point according to the grayscale image features.

[0046] The specific steps in Step 4 shown are:

[0047] Step 4-1 Use the pixel-level corner coordinates obtained in step 3 Harris corner detection to define a rectangle in the direction parallel to the abscissa. The width of the rectangle is 30 pixels and the length is 80% of the side length of the checkerboard. Such as f...

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Abstract

The invention discloses a sub-pixel based angular point calculation method of a camera scaling board, belongs to the field of digital image processing, relates to an angular point detection method inone-click measuring instrument calibration, and aims at overcoming the disadvantage that a practical object size measuring error is large due to inaccurate positioning of the angular point in a planebased template scaling method. Sub-pixel angular point detection based on a grayscale value module replaces a traditional sub pixel method, the angle point position is more accurate, the object detection precision is improved, and it is proved that a sub pixel edge detection algorithm based on the grayscale value module can control the precision of the angular point within 0.1 pixel which doublesthat of other sub pixel angular point detection methods (the angular point precision of other methods is about 0.2 pixel).

Description

technical field [0001] The invention belongs to the field of digital image processing, and relates to a corner detection method in one-button measuring instrument calibration, in particular to a sub-pixel-based camera calibration corner detection method. technical background [0002] With the development of industry, the requirements for product precision measurement are getting higher and higher. Accurately measuring the size of objects plays an important role in precision electronics manufacturing and precision machinery manufacturing. The accuracy of the calibration plays a decisive role in the measurement of the final workpiece. In the calibration method based on the planar template, the image grayscale corner detection algorithm can only detect the pixel-level coordinates of the corner points. The previous sub-pixel-level corner point detection assumes that the gradient vectors are fixed, resulting in sub-pixel positioning. The corners are not precise enough. An ideal...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/00G06T7/13G06T7/80
CPCG01B11/00G06T7/13G06T7/80
Inventor 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
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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