JP3934873B2 - Pattern sheet for camera adjustment, camera adjustment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera adjustment pattern sheet and a camera adjustment method, and more particularly to a technique suitable for use in detecting a surface flaw of a thin steel plate based on a signal generated by photographing the surface of the thin steel plate.
[0002]
[Prior art]
Conventionally, in order to detect surface flaws of a thin steel plate, light is irradiated on the surface of the thin steel plate, and the reflected light is photographed to generate an image signal, which is generated on the surface of the thin steel plate based on the image signal. I'm trying to detect the wrinkles I'm doing.
[0003]
In order to adjust the optical system of the camera that photographs the thin steel sheet, it is necessary to adjust the camera viewpoint, adjust the focus, adjust the camera field of view, and the like. Further, when using a plurality of cameras, it is necessary to further adjust the steps of adjacent cameras after performing the above-described adjustments for each camera. These adjustments are fundamental and important elements for improving the accuracy of the inspection of the thin steel plate, and must be performed accurately.
[0004]
[Problems to be solved by the invention]
However, since the above-mentioned camera adjustment is performed by trial and error, a great amount of time is required. In addition, since the camera adjustment cannot be performed with high accuracy unless it is a certain level of skill, there has been a problem that, in the event of a sudden problem, it may not be possible to respond quickly.
[0005]
The present invention has been made in view of the above-described problems, and it is an object of the present invention to be able to perform camera adjustment accurately in a short time even if it is not a skilled adjuster.
[0006]
[Means for Solving the Problems]
The pattern sheet for camera adjustment of the present invention uses a thin steel plate as a material to be inspected , and includes a plurality of line sensors arranged in the width direction of the material to be inspected for detecting wrinkles generated on the surface of the material to be inspected . the camera, a camera adjustment pattern sheet used to adjust, to adjust the perspective of the plurality of cameras, and the lateral line is labeled along the transverse direction of the pattern sheet center, said plurality of cameras in both end portions in the plurality of imaging regions corresponding to each field of view, and a plurality of vertical lines is labeled by overlapping imaging areas of adjacent cameras, the boundary of the imaging area of each camera with respect to said horizontal line The horizontal line, the plurality of vertical lines, and the thickness of the diagonal line are set based on the horizontal or vertical resolution of the camera. The It is the butterflies.
Also, when the other features of the present invention, the oblique line is characterized in that it is subject at an angle of 15 degrees to 45 degrees relative to the horizontal line.
[0007]
The camera adjustment method of the present invention is a camera adjustment method in which the above-described camera adjustment pattern sheet is attached to a calibration roll, and the calibration roll is rotated and photographed. a first step of adjusting the camera viewpoint swung longitudinally by capturing the horizontal line, by operating the focus adjusting mechanism of the camera, the focus of the camera as described above a plurality of vertical lines appears to be clear a second step of adjusting a third step of adjusting the camera field of view as described above a plurality of vertical lines located at both ends of the field of view for each imaging area of each camera, with respect to the horizontal line the diagonal line is labeled at a predetermined angle taken by a plurality of cameras, the diagonal line taken by adjacent cameras have a fourth step of adjusting waving camera line of sight in the vertical direction so that the straight line , Camera resolution It is characterized in that it has adjustable with high accuracy commensurate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a camera adjustment pattern sheet and a camera adjustment method of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view showing the configuration of the camera adjustment pattern sheet of the present embodiment. In FIG. 1, reference numeral 10 denotes a camera adjustment pattern sheet. As shown in FIG. 1, a horizontal line 12 is marked along the horizontal direction of the center of the camera adjustment pattern sheet 10.
[0009]
The camera adjustment pattern sheet 10 of the present embodiment is photographed by three cameras 1 to 3, and the camera viewpoint, focus, camera field of view, and steps of adjacent cameras can be adjusted by signals output from the cameras. .
[0010]
In order to perform the above-described adjustments, three vertical lines 11 are marked on the camera adjustment pattern sheet 10 of the present embodiment along the vertical direction of both end portions in the field of view of each camera. In the present embodiment, a line sensor camera that averages and outputs the luminance of one column is used.
[0011]
The three vertical lines 11 are marked in an overlapping manner in the shooting areas of adjacent cameras. Specifically, the three vertical lines 11 marked at the right end in the visual field A of the first camera 1 are the three vertical lines 11 marked at the left end in the visual field B of the second camera 2. Are overlapping. In other words, the right end in the field of view A of the first camera 1 and the left end of the field of view B of the second camera 2 overlap, and three vertical lines 11 are marked in the overlapping portion. ing.
[0012]
In addition, the three vertical lines 11 marked at the right end in the field of view B of the second camera 2 and the three vertical lines 11 marked at the left end of the field of view C of the third camera 3 overlap. is doing.
[0013]
Further, in the camera adjustment pattern sheet 10 of the present embodiment, an oblique line 13 marked at a predetermined angle with respect to the horizontal line 12 is marked for each boundary of the photographing area of each camera. The diagonal line 13 is marked at a predetermined angle θ with respect to the horizontal line 12. The angle θ is preferably 15 to 45 degrees, and is set to 30 degrees in the present embodiment.
[0014]
The camera adjustment pattern sheet 10 of the present embodiment configured as described above has three features.
That is, the first feature is that the thickness of the central horizontal line 12 used for matching the viewpoint of the camera is set to about the camera resolution in the vertical direction. The reason why the thickness of the horizontal line 12 is set to about the vertical resolution of the camera is to realize the adjustment with the limit of feasibility (accuracy about the vertical resolution of the camera).
[0015]
The second feature is that the thickness of the three vertical lines 11 used for adjusting the field of view and focus of the camera and the slanted line 13 are set to about the horizontal camera resolution. The reason why the thickness of the three vertical lines 11 is set to about the horizontal resolution of the camera is to realize the adjustment with the limit of feasibility (accuracy about the horizontal resolution of the camera).
[0016]
The third feature is that the inclination of the oblique line 13 used for matching the steps of adjacent cameras is 30 degrees (15 to 45 degrees). As the angle of the oblique line 13 is steep, the step difference is easily detected. However, if the angle θ is too small, the image changes immediately when the roll is rotated, making it difficult to match. Therefore, in the present embodiment, the angle θ of the oblique line 13 is set to 15 to 45 degrees, preferably 30 degrees.
[0017]
As described above, by performing the adjustment using the camera adjustment pattern sheet 10 shown in FIG. 1, it is possible to perform the camera installation adjustment in a short time without being an expert adjuster. Hereinafter, an embodiment in which the camera installation adjustment is performed using the camera adjustment pattern sheet 10 of the present embodiment will be described.
[0018]
FIG. 2 is a diagram showing a state in which the camera adjustment pattern sheet 10 of the present embodiment is attached to the surface of the roll 20 and is photographed by the three cameras 1 to 3. As shown in FIG. 2, the first camera 1 shoots the first shooting area A, the second camera 2 shoots the second shooting area B, and the third camera 3 takes the third shooting. Image area C.
[0019]
When photographing the camera adjustment pattern sheet 10 affixed to the surface of the roll 20 as described above, as shown in FIG. 3, the surface of the camera adjustment pattern sheet 10 is irradiated with illumination 30, and the camera The reflected light from the adjustment pattern sheet 10 is photographed.
[0020]
FIG. 4 is a diagram schematically showing the moving direction of the camera 1 (2, 3). Here, reference numeral 40 denotes a camera lens, which has a volume for focusing.
4A shows how the camera is moved in the vertical direction, FIG. 4B shows how the camera is rotated, and FIG. 4C shows how the camera is moved in the horizontal direction. Yes. FIG. 5 is a diagram schematically showing a waveform displayed on an oscilloscope when the camera viewpoint is adjusted. FIG. 6 is a diagram schematically showing an enlarged view of the three lines when focusing, and FIG. 7 is a flowchart for explaining the adjustment procedure of the camera.
[0021]
Next, the camera viewpoint adjustment (step S71 in FIG. 7) will be described with reference to FIG.
FIG. 5A shows a state in which the camera viewpoint is completely deviated, and the viewpoint adjustment is usually started from this state.
[0022]
In the first operation, when the camera is shaken in the vertical direction (see FIG. 4A), the horizontal line 12 is found in the camera field of view, and when the horizontal line 12 barely enters the camera field of view, it is shown in FIG. In this way, a portion encircled by a square wave on the oscilloscope appears.
[0023]
Therefore, the camera is rotated from right to left (see FIG. 4B), and as shown in FIG. 5C, the direction in which the beaten portion becomes larger is found, and the direction (hereinafter referred to as “rotation”) is gradually found. Rotate the camera in the “Direction”). As a result, the beaten portion as shown in FIG. 5D, FIG. 5E, and FIG.
[0024]
Then, as shown in FIG. 5 (g), when all the square wave portions disappear and the black level is reached, the adjustment of the camera viewpoint is completed. Therefore, if it is confirmed that the signal level slightly increases as shown in FIG. 5 (h) when the camera is shaken up or down, it can be confirmed that there is no mistake in the adjustment so far. Therefore, the confirmation operation is completed when the camera is again swung upward or downward and returned to FIG. 5 (i).
[0025]
Next, the focus adjustment operation (step S72 in FIG. 7) will be described.
FIG. 6 is a diagram schematically showing an enlarged view of the three lines when focusing. While observing the three lines marked on the camera adjustment pattern sheet 10 of FIG. 1 with an oscilloscope, the focus adjustment portion of the camera is turned so that the three lines can be seen most clearly.
[0026]
For example, as shown in FIG. 6, when the focus adjustment portion of the camera is turned, it becomes clear, sharp, and long in the order of FIGS. 6 (a), 6 (b), and 6 (c). . As shown in FIG. 6C, if it looks sharp and long, the focus is achieved, and the focus adjustment is completed.
[0027]
Next, the camera visual field adjustment (step S73 in FIG. 7) will be described. The camera field of view is adjusted by looking at the image, not the camera signal. In the case of the present embodiment, the adjustment of the camera field of view is completed by aligning the three lines 11 for each of the first camera 1, the second camera 2, and the third camera 3 as shown in FIG.
[0028]
Next, step adjustment (step S74 in FIG. 7) between adjacent cameras will be described.
When the images of the adjacent cameras are viewed and the oblique line 13 is cut and can be observed, the step cannot be adjusted between the adjacent cameras. In this case, the step adjustment between the adjacent cameras can be completed by slightly shaking the camera up and down so that there is no place where the oblique line 13 appears to be cut off.
[0029]
In the above-described embodiment, the case where the camera adjustment pattern sheet 10 corresponding to the field of view of the three cameras is configured and the flaw inspection of the thin steel plate is performed using the three cameras has been described. The present invention can be used well when adjusting one camera.
[0030]
When the number of cameras is one as described above, the diagonal line 13 in FIG. 1 is not necessary, and the step adjustment of the adjacent cameras in step S74 is not necessary, and only the viewpoint adjustment, the focus adjustment, and the visual field adjustment are performed. It will be better.
[0031]
【The invention's effect】
As described above, according to the present invention, according to the present invention, a horizontal line is marked at the center of the camera adjustment pattern sheet used to adjust the camera for detecting wrinkles generated on the surface of the material to be inspected. The camera's viewpoint can be easily adjusted, and it has become easier to perform focus adjustment and visual field adjustment by marking multiple vertical lines along the vertical direction of both ends in the visual field of the camera. Even if you are not an adjuster, you can adjust the camera accurately in a short time.
According to another feature of the present invention, a diagonal line marked at a predetermined angle with respect to the horizontal line is marked on the boundary of the shooting area of the camera. Adjustment necessary when detecting wrinkles generated on the surface can be simplified.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment of a camera adjustment pattern sheet of the present invention.
FIG. 2 is a diagram illustrating a state in which the camera adjustment pattern sheet according to the embodiment is attached to a roll and is photographed by a plurality of cameras.
FIG. 3 is a diagram illustrating a state in which a camera adjustment pattern sheet attached on a roll is illuminated and reflected light is captured by a camera.
FIG. 4 is a diagram illustrating an arrangement state of a camera and a calibration roll, and a diagram schematically illustrating a moving direction of the camera.
FIG. 5 is a diagram schematically showing a waveform displayed on an oscilloscope when the camera viewpoint is adjusted.
FIG. 6 is a diagram schematically showing an enlarged view of three lines when focusing.
FIG. 7 is a flowchart for explaining a camera adjustment procedure;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st camera 2 2nd camera 3 3rd camera 10 Pattern sheet 11 for camera adjustment 3 vertical line 12 Horizontal line 20 Calibration roll 30 Illumination 40 Focusing 13 in camera part Diagonal line A 1st Camera view B Second camera view C Third camera view

Claims (3)

Camera adjustment used to adjust a plurality of cameras composed of line sensors arranged in the width direction of the inspection material in order to detect wrinkles generated on the surface of the inspection material using a thin steel plate as the inspection material Pattern sheet for
In order to adjust the viewpoints of the plurality of cameras, a horizontal line marked along the horizontal direction of the center of the pattern sheet;
In both end portions in the plurality of imaging regions corresponding to each view of the plurality of cameras, a plurality of vertical lines is labeled by overlapping imaging areas of adjacent cameras,
The boundary of the imaging area of each camera, and a diagonal line is labeled at a predetermined angle with respect to the horizontal line,
The camera adjustment pattern sheet , wherein the horizontal line, the plurality of vertical lines, and the thickness of the diagonal line are set based on the horizontal or vertical resolution of the camera. 2. The camera adjustment pattern sheet according to claim 1 , wherein the diagonal line is marked at an angle of 15 to 45 degrees with respect to the horizontal line. A camera adjustment method performed by attaching the pattern sheet for camera adjustment according to claim 1 or 2 to a calibration roll and rotating the calibration roll while photographing.
A first step of adjusting the camera viewpoint by photographing the horizontal shaking the camera line of sight in the vertical direction,
By operating the focus adjusting mechanism of the camera, a second step of the plurality of vertical lines to adjust the focus of the camera to look like clear,
A third step of adjusting the camera field of view so that the plurality of vertical lines are positioned at both ends of the field of view ;
For each shooting area of each camera, diagonal lines marked at a predetermined angle with respect to the horizontal line are shot with a plurality of cameras, and the camera line of sight is vertically aligned so that the diagonal lines shot with adjacent cameras are in a straight line. shaken to have a fourth step of adjusting,
A camera adjustment method characterized in that it can be adjusted with high accuracy corresponding to the camera resolution .

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