Anti-interference target laser ray extraction method

Abstract

The invention discloses an anti-interference target laser ray extraction method. The method comprises the following steps of S1, performing Gaussian filtering processing on an image; s2, determining possible starting and ending position points of the target laser ray: the starting and ending position points of the target laser ray are respectively b and b1, the difference value of two adjacent pixel gray values is diffval, and the determination method of b and b1 is as follows: the determination method of b: b-a < = diffval and c-b > = diffval; the determination method of b1 is as follows: b1-a1 is greater than or equal to-diffval, and b1-c1 is less than or equal to-diffval; wherein a and c are two adjacent points on the two sides of b in the width direction of the laser line respectively, and a1 and c1 are two adjacent points on the two sides of b1 in the width direction of the laser line respectively; s3, setting the line width of a target laser line; s4, extracting the center point of the target laser ray: extracting the center of the laser ray by using a gray gravity center method; s5, extracting a target laser ray; the method can be applied to the 3D laser contourgraph to extract correct laser rays under the condition of interference, and serious loss of industrial production caused by inaccurate extraction of the laser rays is avoided. According to the invention, the laser line extraction precision is improved.

Description

Technical Field

[0001] The invention relates to the technical field of laser line extraction, in particular to an interference-resistant target laser line extraction method. Background Art

[0002] 3D laser profilers are widely used in manufacturing (such as workpiece inspection), the automotive industry (such as component measurement and quality control), the construction industry (such as structural scanning), the medical field (such as volume measurement and surgical planning), and the robotics field (such as path planning and environmental perception). They are used for high-precision measurement and inspection to help improve product quality and production efficiency.

[0003] Commonly used traditional laser stripe center extraction methods include grayscale centroid method, threshold method, extreme value method and Steger algorithm. When the laser line is projected onto a conventional non-reflective workpiece, only one laser line approximately obeying the Gaussian distribution is formed. The target laser line can be extracted by any of the above methods. When the workpiece is transparent or reflective, when the laser line is projected onto the workpiece to be measured, multiple laser lines may be formed or interfering light spots and bright spots may appear due to the influence of scattered light. At this time, it is difficult to extract the target laser line by the above traditional methods. In order to solve the influence of interference, the present invention proposes an anti-interference target laser line extraction method. Summary of the invention

[0004] The object of the present invention is to provide an interference-resistant target laser line extraction method, aiming to solve the problem that it is difficult to extract the correct target laser line when the laser line is interfered.

[0005] The present invention is achieved in that:

[0006] An anti-interference target laser line extraction method comprises the following steps:

[0007] S1, perform Gaussian filtering on the image;

[0008] S2. Determine the possible starting and ending points of the target laser line: The starting and ending points of the target laser line are b and b1 respectively. The difference between the gray values ​​of two adjacent pixels is diffval. The method for determining b and b1 is as follows:

[0009] b is determined by: ba≤diffval and cb≥diffval; b1 is determined by: b1-a1≥-diffval and b1-c1≤-diffval; a and c are two adjacent points on both sides of b in the laser line width direction, and a1 and c1 are two adjacent points on both sides of b1 in the laser line width direction;

[0010] S3, setting the line width of the target laser line: according to step S2, determine the starting position point of the target laser line, calculate the line width W=b1-b at each starting and ending position, and set the possible line width range W of the target laser line min ~W max , when the line width satisfies W min ≤W≤W max It may be the target laser line;

[0011] S4. Extract the center point of the target laser line: Use the grayscale centroid method to extract the center of the laser line. The formula used is as follows:

[0012]

[0013] Where I(i,j) represents the grayscale value of the image at (i,j), bi and bj represent the pixel positions of the starting point b, and b1i and b1j represent the pixel positions of the ending point b1;

[0014] S5, extracting the target laser line, specifically comprising the following steps:

[0015] S51, the brightest laser point in the first row is selected as the target laser line;

[0016] S52, select the target laser line in the second row that is closest to the target laser line in the first row in the x direction;

[0017] S53, select the laser line in the third row that is closest to the average value of the first and second rows in the x direction;

[0018] S54, repeat steps S51-S53 until the nth row in the x direction closest to the average value of the previous n-1 rows in the x direction is the target laser line;

[0019] S55, determining the target laser line of the subsequent row.

[0020] Furthermore, in step S1, a 5*5 Gaussian filter is performed on the image.

[0021] Furthermore, in step S55, the target laser line is the one whose x-direction distance of the current row is closest to the average value of the previous n rows in the x-direction.

[0022] Furthermore, in step S55, n can be set to different sizes according to the extraction effect.

[0023] Furthermore, step S5 also includes the following steps:

[0024] S56, the current n rows are invalid values, i.e. no laser points are extracted, the n+1th row is valid values, i.e. valid points are extracted successfully, and the method for determining the target laser points in the n+1th row is the same as that in the first row.

[0025] Compared with the prior art, the invention has the following beneficial effects: the invention can be applied to extract the correct laser line in the 3D laser profiler under interference, avoiding serious losses to industrial production caused by inaccurate laser line extraction. The invention improves the accuracy of laser line extraction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but they do not constitute a limitation of the present invention. In the accompanying drawings, each element or part is not necessarily drawn according to the actual scale.

[0027] Figure 1 is the Gaussian profile of the laser line;

[0028] Figure 2 is the extracted laser spot map;

[0029] Figure 3 is the extracted target laser line map;

[0030] Figure 4 It is the target laser spot diagram determined using the present invention. DETAILED DESCRIPTION

[0031] The following drawings describe in detail the specific embodiments of the present invention. The embodiments are intended to further explain the present invention, rather than to limit the present invention.

[0032] An anti-interference target laser line extraction method comprises the following steps:

[0033] S1. Perform 5*5 Gaussian filtering on the image. The size of the filter kernel can be increased or decreased according to the actual situation.

[0034] S2. Determine the possible starting and ending points of the target laser line: the laser line is brightest in the middle, and the light intensity decreases as it extends to the periphery. This distribution rule conforms to the Gaussian distribution, such as Figure 1 shown.

[0035] The starting and ending points of the target laser line are b and b1 respectively. The difference between the gray values ​​of two adjacent pixels is diffval. The method for determining b and b1 is as follows:

[0036] The method for determining b is: ba≤diffval and cb≥diffval; the method for determining b1 is: b1-a1≥-diffval and b1-c1≤-diffval; among them, a and c are two adjacent points on both sides of b in the width direction of the laser line, and a1 and c1 are two adjacent points on both sides of b1 in the width direction of the laser line.

[0037] S3, setting the line width of the target laser line: according to step S2, determine the starting position point of the target laser line, calculate the line width W=b1-b at each starting and ending position, and set the possible line width range W of the target laser line min ~W max , when the line width satisfies W min ≤W≤W max It may be the target laser line. Some interference points can be filtered out by limiting the width of the target laser line.

[0038] S4. Extract the center point of the target laser line: Use the grayscale centroid method to extract the center of the laser line. The formula used is as follows:

[0039]

[0040] Where I(i,j) represents the grayscale value of the image at (i,j), bi and bj represent the pixel positions of the starting point b, and b1i and b1j represent the pixel positions of the ending point b1.

[0041] Set diffval=10, W min =3,W max =100, the extracted results are as follows Figure 2 As shown, the green point in the figure is the extracted possible center point of the laser line.

[0042] S5, extracting the target laser line, specifically comprising the following steps:

[0043] S51. Select the brightest laser point in the first row as the target laser line.

[0044] S52, select the second row that is closest to the target laser line in the first row in the x direction as the target laser line.

[0045] S53, select the laser line in the third row that is closest to the average value of the first and second rows in the x direction in the x direction.

[0046] S54, repeat steps S51-S53 until the target laser line is the one whose x-direction distance to the average value of the previous n-1 rows is the nth row.

[0047] S55, determining the target laser line of the subsequent row, the target laser line is the one whose x direction of the current row is closest to the average value of the x direction of the previous n rows, and n can be set to different values ​​according to the extraction effect, such as 5 or 10.

[0048] S56, the current n rows are invalid values, i.e. no laser points are extracted, the n+1th row is valid values, i.e. valid points are extracted successfully, and the method for determining the target laser points in the n+1th row is the same as that in the first row.

[0049] The extracted target laser line image and the target laser point determined by the method of extracting the target laser line are respectively Figure 3 and Figure 4 shown. Figure 3 In the figure, the red dot is the center point of the extracted target laser line. Figure 4 The red dot in the middle is the target laser point determined according to the above method for extracting the target laser line.

[0050] The present invention can be applied to extract the correct laser line in a 3D laser profiler under interference conditions, thereby avoiding serious losses to industrial production caused by inaccurate laser line extraction. In addition, the present invention improves the accuracy of laser line extraction.

[0051] Although the present invention has been described in detail according to the previous embodiments, those skilled in the art should understand that they can still modify the technical solutions in the described embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements will not change the essence of the relevant technical solutions and make them exceed the technical scope defined by the various embodiments of the present invention. Except for the technical features described in the specification, all other technical features are known to those skilled in the art.

Claims

1. A method for extracting target laser lines with anti-interference, characterized in that: The following steps are involved: S1, perform Gaussian filtering on the image; S2. Determine the possible starting and ending points of the target laser line: The starting and ending points of the target laser line are b and b1 respectively. The difference between the gray values ​​of two adjacent pixels is diffval. The method for determining b and b1 is as follows: b is determined by: ba≤diffval and cb≥diffval; b1 is determined by: b1-a1≥-diffval and b1-c1≤-diffval; a and c are two adjacent points on both sides of b in the laser line width direction, and a1 and c1 are two adjacent points on both sides of b1 in the laser line width direction; S3, setting the line width of the target laser line: according to step S2, determine the starting position point of the target laser line, calculate the line width W=b1-b at each starting and ending position, and set the possible line width range W of the target laser line min ~W max , when the line width satisfies W min ≤W≤W max It may be the target laser line; S4. Extract the center point of the target laser line: Use the grayscale centroid method to extract the center of the laser line. The formula used is as follows: Where I(i,j) represents the grayscale value of the image at (i,j), bi and bj represent the pixel positions of the starting point b, and b1i and b1j represent the pixel positions of the ending point b1; S5, extracting the target laser line, specifically comprising the following steps: S51, the brightest laser point in the first row is selected as the target laser line; S52, select the target laser line in the second row that is closest to the target laser line in the first row in the x direction; S53, select the laser line in the third row that is closest to the average value of the x direction of the first row and the second row; S54, repeat steps S51-S53 until the nth row in the x direction closest to the average value of the previous n-1 rows in the x direction is the target laser line; S55, determining the target laser line of the subsequent row.

2. The method for extracting target laser lines with anti-interference according to claim 1, characterized in that: In the step S1, a 5*5 Gaussian filter is performed on the image.

3. The method for extracting target laser lines with anti-interference according to claim 1, characterized in that: In step S55, the target laser line is the one whose x-direction distance of the current line is closest to the average value of the previous n lines in the x-direction.

4. The method for extracting target laser lines with anti-interference according to claim 3, characterized in that: In step S55, n can be set to different sizes according to the extraction effect.

5. The method for extracting target laser lines with anti-interference according to claim 3, characterized in that: Step S5 also includes the following steps: S56, the current n rows are invalid values, i.e. no laser points are extracted, the n+1th row is valid values, i.e. valid points are extracted successfully, and the method for determining the target laser points in the n+1th row is the same as that in the first row.

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