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Sub-pixel peak point extracting algorithm based on Bezier curve

A Bezier curve and peak point technology, applied in the field of geometric measurement, can solve problems such as calculation result errors, non-normal distribution of fringe images, and inability to calculate the coordinates of gray peak points, etc., to achieve accurate peak point positions and stable calculations Reliable, simple algorithm calculation effect

Active Publication Date: 2019-01-01
HEFEI UNIV OF TECH
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Problems solved by technology

For this case, the coordinates of the gray peak point cannot be calculated by using the existing algorithm;
[0005] (2) The existing algorithm approximates the gray value distribution of the laser stripe image to a normal distribution, but in actual situations, since the laser emitted by the laser transmitter is not strictly perpendicular to the measured plane, the camera lens and the phase plane and the laser stripe are located The planes are not strictly parallel, which leads to the fact that the intensity distribution of the actually collected fringe images is not a normal distribution, which easily leads to large errors in the calculation results.

Method used

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  • Sub-pixel peak point extracting algorithm based on Bezier curve
  • Sub-pixel peak point extracting algorithm based on Bezier curve
  • Sub-pixel peak point extracting algorithm based on Bezier curve

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Embodiment 1

[0033] This embodiment is to extract the peak point in a row of pixels of the structured light stripe image, including the following steps:

[0034] Step (1): Collect the laser stripe image and perform preprocessing such as gray scale transformation, image filtering and image segmentation;

[0035] Step (2): Traverse the preprocessed image line by line, compare the gray value of each point, and determine the four control vertices of the Bezier curve.

[0036] (2a) Suppose a point p in the i-th row of the image j =(x j ,y i ,) (i=0,...,n) gray value z j , traverse the pixel gray value line by line from left to right to find the first maximum gray value point p of each line m =(x m ,y i );

[0037] (2b) vs z m ,z m+1 and z m+2 , if z m =z m+1 =z m+2 , at this time there is saturation in the image, at this time from left to right from p m Point to start traversing the pixel gray value of the row, find the first one that satisfies z w m point p w=(x w ,y i ), at ...

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Abstract

The invention discloses a method for extracting the edge points of a weld seam after welding based on line scanning data. Firstly, a laser fringe image is collected by a camera and input to a computer, and the image is preprocessed; secondly, the preprocessed image is traversed line by line, and the gray values of the points are compared to determine the four control vertexes of a Bezier curve; and the four control vertexes are substituted into a cubic Bezier curve parameter equation to calculate the coordinates of a sub-pixel peak point. The invention provides a universal, fast and accurate sub-pixel accuracy peak point calculation method for the laser line scanning measurement technology, and the calculation result is reliable.

Description

technical field [0001] The invention relates to the field of geometric quantity measurement, in particular to a Bezier curve-based sub-pixel peak point extraction algorithm in laser line scanning measurement technology. Background technique [0002] In industrial production, in order to ensure the manufacturing accuracy of products, it is often necessary to carry out accurate three-dimensional measurement of the geometric dimensions of products. In practical applications, for products or parts with complex geometric dimensions and high precision requirements, the traditional manual measurement or contact measurement currently used has problems such as low efficiency and sparse sampling points, which cannot meet the efficiency and precision requirements of industrial production. Using laser line scanning or other methods of non-contact measurement is an effective way to solve the above problems, and is currently a common technical means for the detection of complex shape part...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/25
CPCG01B11/2518
Inventor 李维诗刘家辰于连栋夏豪杰何佳敏
Owner HEFEI UNIV OF TECH