JP6412474B2 - Crack width measurement system - Google Patents

Description

  The present invention relates to a crack width measuring system that measures the width of a crack on the surface of a structure.

In recent years, social infrastructure such as bridges and roads has been required to have a longer life span and earthquake resistance measures, and infrastructure maintenance costs have increased. One form of deterioration of concrete structures is cracks, which are important indicators for confirming the stress state of structures and predicting seismic performance.
Conventionally, this crack has been measured by visual measurement using a crack scale and sketches of crack conditions, but there are problems with measurement accuracy and objectivity, and it uses a digital camera and a PC (personal computer). A system for measuring the crack width by an image processing technique has been devised (see Patent Document 1).

  Specifically, Patent Document 1 discloses an imaging means for imaging the surface of a concrete column to be inspected, and two parallels for displaying two points having a reference distance between the imaging object portion on the surface of the concrete column. A parallel beam irradiating means for irradiating a beam, the imaging means and the parallel beam irradiating means are installed on the upper part thereof, and the imaging means and the parallel beam irradiating means are moved up and down along the concrete column to be inspected. A support pole configured to be extendable, an image monitor that displays an image of the concrete pillar photographed by the photographing means, and other necessary items, and a concrete pillar image photographed by the photographing means are selected. Data storage means for storing desired image data, data specifying the concrete column, and data specifying the imaging target part, and Means and a computing device equipped with a remote control function of the support poles, in structure surface inspection imaging device of the concrete column is disclosed.

JP 2009-168752 A

In the imaging device for surface inspection in Patent Document 1, since the inspection object is irradiated with two parallel beams having a reference distance, measurement can be performed without facing the inspection object. When it is away from the object, it becomes impossible to irradiate the inspection object with two parallel beams. For this reason, in order to move the imaging means and the parallel beam irradiation means up and down, a support pole configured to be extendable and retractable is provided, so that it is possible to irradiate the inspection object at a high place and to measure the crack width. I am doing so.
However, the photographing device for concrete surface inspection disclosed in Patent Document 1 is limited to photographing concrete columns, and cannot be directly applied to the measurement of cracks on the surface of a concrete structure.
In addition, it is not assumed that the camera attached to the tip of the pole swings when the pole is shaking due to an external factor such as a wind when performing an inspection at a high place. Therefore, there is a problem that an accurate crack width cannot be measured when the pole swings.

  An object of the present invention is to provide a crack width measuring system capable of measuring an accurate crack width even when the pole is swaying due to external factors such as wind.

In order to solve the above problems, a crack width measuring system for measuring the width of a crack on a surface to be inspected according to the present invention is an image pickup unit that photographs a surface to be inspected including a structure having a rectangular frame shape from an opposite direction. And a display unit that displays a rectangular guide superimposed on a captured image of the surface to be inspected captured by the imaging unit in accordance with an operation instruction by a predetermined amount, and the imaging unit and the imaging unit capture images. A distance sensor that measures the distance between the inspection target surfaces, and the frame shape in the captured image of the inspection target surface displayed on the display unit and the side of the guide that is trapezoidally distorted by the predetermined amount are in a parallel state And a measurement image creating unit that performs image conversion for collimation angle compensation that compensates for deformation of the image due to a collimation angle that is an angle of inclination from a facing direction to the inspection target surface, and the display unit Inspection surface to be displayed Crack width crack was to measure.

  According to the present invention, even when the pole is swaying due to an external factor such as a wind, when checking the high place, the collimation angle of the inspection target surface is grasped by the camera attached to the tip of the pole. Since the collimation angle can be compensated, an accurate crack width can be measured.

It is a figure which shows schematic structure of a crack width measuring system. It is a figure explaining deformation | transformation of a picked-up image. It is a figure which shows the structure of the control part of a crack width measurement system. The setting screen of collimation angle setting displayed on a tablet part is shown. It is a figure which shows the measurement flow of a crack width. It is a figure which shows an example of a crack scale image. It is a figure explaining the superposition of a crack scale image and a crack image. It is a figure which shows the measurement flow of another crack width.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Drawing 1 is a figure showing the schematic structure of the crack width measuring system of an embodiment.

"System configuration"
The crack width measurement system according to the embodiment includes an inspection device unit 100 that images a surface to be inspected such as a concrete structure, and a tablet unit 200 that displays a captured image and gives a measurement instruction.
The inspection device unit 100 includes a camera 103, a distance sensor 104 that measures the distance between the camera 103 and the surface to be inspected, and a cloud that rotates and fixes the installation direction of the camera 103 and the distance sensor 104 in a horizontal direction or a vertical direction. A platform 102 and a pan head 102 at one end, and a telescopic pole 101 fixed to a frame such as a tripod.

  The pole 101 is configured such that a plurality of tubes having different diameters are inserted into each other in a telescopic manner so that the height of the camera 103 and the distance sensor 104 of the pan head 102 can be adjusted according to the surface to be inspected. ing. In addition, a mechanism for electrically moving up and down by a motor with a built-in pole is provided, and the inspection apparatus control unit 110 described later adjusts the expansion and contraction of the pole 101 according to the height of the inspection target surface.

Similarly, the camera platform 102 is also rotated by a motor (not shown), and the directions of the camera 103 and the distance sensor 104 are rotated in the vertical direction (102A) and the horizontal direction (102B) as shown in the figure.
As a result, the crack width at a predetermined position on the inspection target surface can be measured, and the surface distribution and width of the crack on the inspection target surface can be reduced by repeatedly rotating the pan head 102 and expanding and contracting the pole 101. It can be measured.

  The distance sensor 104 is a distance meter that irradiates a measurement point with a visible light laser and calculates the distance to the measurement point from the phase difference between the irradiation light and the reflected light. The visible light laser irradiation axis of the distance sensor 104 and the imaging axis of the camera 103 are substantially aligned with each other, and is installed on the pan head 102.

The inspection device control unit 110 controls the camera 103 and the distance sensor 104 based on an instruction from the tablet unit 200. Further, the position of the inspection target surface is controlled by controlling the pan head 102 and the pole 101.
The tablet unit 200 is a control unit that displays a captured image of the inspection target surface and measures a crack width, and will be described in detail later.

<Measurement method of crack width>
Next, a measurement method for the first crack width measurement will be described.
The crack width measurement system of the embodiment first detects a crack image by performing image processing on a digital image of the inspection target surface photographed by the camera 103. Specifically, image processing such as RGB color conversion (monochrome conversion), thinning (edge detection), and binarization is performed to obtain a crack image. Next, the number of image pixels of the crack image corresponding to the crack width is obtained. The crack width can be detected by calculating the actual size from the number of image pixels.
Note that the method for obtaining the number of image pixels of the crack image corresponding to the crack width is not particularly limited and will not be described here.

This actual size is the product of the number of image pixels of the crack image and the size of the image pixel (element size of the image sensor of the camera 103), the distance between the lens of the camera 103 and the image sensor, the lens of the camera 103, and the inspection object. Calculation is performed based on the imaging magnification of the camera 103 determined from the distance between the surfaces.
Here, the distance between the lens of the camera 103 and the surface to be inspected is measured by the distance sensor 104 installed on the camera platform 102 together with the camera 103.

<Keystone correction>
By the way, when photographing the inspection target surface with the camera 103, if the photographing is performed at an angle from the facing direction (photographing from an oblique direction), the captured image of the inspection target surface is distorted. For example, a rectangular figure on the inspection target surface is distorted in a trapezoidal shape as shown in FIG. Specifically, FIG. 2 is a view of the camera 103 in FIG. 1 as viewed from above. The camera 103B, the camera 103A, and the camera 103C in FIG. θc, θa, θb) are shown. The trapezoidal deformation amounts of the photographed image c, the photographed image a, and the photographed image b indicating the photographed image of the camera 103 increase in the order of the tilt θc>θa> θb of the camera 103. Although FIG. 2 shows an example in which the collimation direction is inclined in the horizontal direction, the collimation direction may be inclined in the vertical direction or the oblique direction. In the following description, the amount of tilt of the collimation direction of the camera 103 from the directly facing direction is referred to as a collimation angle.

The captured image of the crack is also deformed by the tilt of the collimation direction of the camera 103. For this reason, the dimension of the crack width calculated | required from the picked-up image contains the error according to the inclination (collimation angle) of a collimation direction.
Image distortion due to the tilt of the collimation direction of the camera 103 can be compensated by geometric transformation such as projective transformation. Therefore, in the measurement of the crack width, when image processing is performed on the digital image of the inspection target surface captured by the camera 103, first, the collimation angle compensation of the captured image captured by the camera 103 is performed on the captured image of the inspection target surface. Thus, the image is converted into a photographed image obtained by facing the inspection target surface.

  Since the camera 103 is fixed to a gantry such as a tripod, the collimation direction of the camera 103 described above changes depending on the shooting position on the surface to be inspected and also changes due to the influence of wind and the like. Hereinafter, the crack width measurement control method of the crack width measurement system of the embodiment will be described in more detail.

<Control unit configuration>
Drawing 3 is a figure showing the composition of the control part of the crack width measurement system of an embodiment.
The inspection device control unit 110 includes a camera control unit 111 that controls the operation of the camera 103 (see FIG. 1), a distance sensor control unit 112 that controls distance measurement between the camera 103 and the inspection target surface, and a pan head 102. (See FIG. 1) and a pan head / pole control unit 113 that controls the rotation of the pole 101 (see FIG. 1) and controls the control based on an instruction from the tablet unit 200 via the communication unit 114. Do it.
The photographed image of the camera 103 is notified to the tablet unit 200 via the camera control unit 111 and the communication unit 114, and the distance between the camera 103 and the inspection target surface measured by the distance sensor 104 (see FIG. 1). Is notified to the tablet unit 200 via the distance sensor control unit 112 and the communication unit 114.

The communication unit 201 of the tablet unit 200 is connected to the communication unit 114 of the inspection device control unit 110 by wireless or wired communication, and exchanges instruction information, captured images, and distance information.
The captured image of the camera 103 is notified to the measurement image creation unit 204 and the image acquisition unit 206 via the communication units 114 and 201, and the distance information between the camera 103 and the inspection target surface measured by the distance sensor 104 is The measurement image creation unit 204 is notified and the crack width is obtained.

  The measurement image creation unit 204 performs projective conversion on the captured image of the camera 103 to perform collimation angle compensation, performs image processing based on the converted captured image, and obtains a crack image. Then, the actual size of the crack width is calculated from the number of image pixels of the crack image based on the distance information between the camera 103 and the inspection target surface.

  The compensation condition setting unit 207 sets a compensation condition when the measurement image creation unit 204 performs collimation angle compensation of a captured image. More specifically, a projective transformation matrix is obtained from the collimation angle. This collimation angle is, for example, the tilt of the camera 103 from the directly-facing state of the collimation direction, and the camera 103 is rotated slightly in one direction, and the distances in three or more directions are measured. calculate. Although details will be described later, when the collimation angle cannot be calculated from the distance information due to the shaking by the wind, the compensation condition is manually set by the guide display method.

The image acquisition unit 206 acquires a captured image of the camera 103 and stores it in an image memory (not shown).
The measurement image synthesis unit 205 synthesizes the measurement result of the crack width of the measurement image creation unit 204 on the image memory so as to be displayed corresponding to the crack image of the captured image of the camera 103.

A display unit 203 is a display unit of the crack width measurement system of the embodiment, displays measurement conditions and operation contents, and operates in cooperation with the input unit 202 described later. Then, the measurement image composition unit 205 displays a captured image in which the measurement value of the crack width is written on a display device such as an LCD. Further, guide display for manual setting of compensation conditions is performed by the guide display control unit 2031.
The method for manually setting the compensation condition by the guide display will be described later in detail with reference to FIG.

The input unit 202 is an input unit that performs operation instructions and settings of the crack width measurement system of the embodiment. A touch panel or the like is pasted on the display unit 203, and input is performed with a finger or a stylus pen. Also, an operation with a mouse may be used.
The automatic measurement / manual setting unit 2021 of the input unit 202 determines and sets whether to calculate the collimation angle based on the distance measurement value and automatically set the compensation condition or to manually set the compensation condition. During this manual operation, guide display control is performed in cooperation with the compensation condition setting unit 207.

  The measurement image creation unit 204, the compensation condition setting unit 207, the automatic measurement / manual setting unit 2021, and the like are realized by a CPU (Central Processing Unit) included in the tablet unit 200 executing software stored in the storage unit. Can do.

《Projection transformation matrix acquisition method》
Hereinafter, a method for setting compensation conditions by guide display will be described with reference to FIG. In this method, when photographing is performed with the collimation direction of the camera 103 tilted from the directly-facing state of the surface to be inspected, an incidental structure such as a window frame having a rectangular shape on the surface to be inspected is captured in a trapezoidal shape. I use that. Specifically, a projection transformation matrix for collimating angle compensation is obtained with reference to the shape of an incidental structure such as a window frame of a captured image.

FIG. 4 shows a collimation angle setting screen displayed on the tablet unit 200. On the screen, a captured image of the surface to be inspected acquired by the image acquisition unit 206 and a guide 410 that is displayed and controlled by a guide display control unit 2031 to be described later are displayed in an overlapping manner.
A frame display 420 in FIG. 4 represents a captured image of a window frame having a rectangular shape of the inspection target surface.

  The rectangular guide 410 is displayed with a trapezoidally distorted shape like the guides 411, 412, and 413 by operating the stylus pen 400. Specifically, when the stylus pen 400 is right-dragged in the horizontal direction (the lateral direction of the paper), the trapezoidally distorted guide 411 or the guide 412 or the guide corresponding to the case where the rectangular guide 410 is photographed from an oblique direction at a predetermined collimation angle. 413 is displayed. In the following description, an angle corresponding to this collimation angle is referred to as a correction angle. The shapes of the guides 411, 412, and 413 can be geometrically determined according to the correction angle. In FIG. 4, three guides 411, 412, and 413 are shown, but actually, one guide having a different trapezoidal distortion is displayed in conjunction with the drag of the stylus pen 400. When the stylus pen 400 is dragged in the reverse direction, the guide is trapezoidally distorted in the reverse direction.

  The operator of the crack width measuring system of the embodiment adjusts the drag amount (corresponding to the correction angle) of the stylus pen 400 so that the guide 410 is equivalent to the frame display 420 imaged by trapezoidal distortion. Specifically, the drag amount (correction angle) is adjusted so that the trapezoidally distorted figure (411, 412, 413) of the guide 410 and the oblique side of the frame display 420 are in a parallel state. If the guide 412 has the same trapezoidal distortion as the frame display 420, the correction angle when the guide 412 is displayed becomes the collimation angle of the camera 103 that images the inspection target surface.

The projection transformation matrix for collimation angle compensation is obtained from the coordinate values of the four vertices of the guide 410 and the guide 412. That is, a projective transformation matrix for converting the vertex 412a to the vertex 410a, converting the vertex 412b to the vertex 410b, converting the vertex 412c to the vertex 410c, and converting the vertex 412d to the vertex 410d is obtained.
If the captured image of the inspection target surface imaged by the camera 103 is subjected to projective conversion using the obtained projective transformation matrix, it can be converted into a captured image acquired by facing the inspection object surface, and the crack width can be measured with high accuracy.

In the description of FIG. 4, the collimation angle compensation in the horizontal direction has been described. However, the collimation angle compensation in the vertical direction can be performed by dragging in the vertical direction and displaying the guide 410 with trapezoidal distortion in the vertical direction. it can.
Further, the collimating angle compensation in the oblique direction can be performed by combining the collimating angle compensation in the horizontal direction and the vertical direction. By obtaining the collimation angle in order by dragging in the horizontal direction and dragging in the vertical direction, it is possible to easily obtain the collimation angle compensation in the oblique direction.

The flow of measuring the crack width of the crack width measuring system of the embodiment will be described with reference to FIG.
In step S501, the distance from the camera 103 to the inspection target surface is measured by the distance sensor 104. And a measurement result is preserve | saved in order to calculate the average and the fluctuation | variation at the time of determining whether collimation angle setting by the guide display mentioned later is performed (S502). Thereafter, the number of times of measurement is increased by 1 (S503), and the number of times of measurement is compared with a specified value (S504).

In step S504, when the number of measurements has not reached the specified value (Yes in S504), the process returns to step S501, and the distance measurement from the camera 103 to the inspection target surface is repeated.
In step S504, if the number of measurements has reached the specified value (No in S504), the process proceeds to step 505. This distance measurement is performed continuously for a fixed time (5 times at 500 msec intervals).

In step S505, an average value and a fluctuation amount of the result of the distance measurement (S501) performed the specified number of times are calculated.
Next, the variation value of the distance measurement is compared with a predetermined threshold value (S506). Thereby, it is determined whether or not the camera 103 is swinging due to the influence of wind or the like, and it is determined whether or not the collimation angle is automatically detected by the distance sensor integrated with the camera 103.

If the variation value of the distance measurement is less than the predetermined threshold value in step S506 (Yes in S506), the process proceeds to processing (S507 to S509) for automatically detecting the next collimation angle and calculating the projective transformation matrix.
If the variation value of the distance measurement is greater than or equal to the predetermined threshold value in step S506 (No in S506), the collimation angle cannot be automatically detected, and thus the projection transformation matrix acquisition process based on the guide display described in FIG. 4 (S513 to S516). To do.

  In step S507, the distance between the inspection target surface and the camera 103 is measured at three or more points with a predetermined angle difference in one direction, and a collimation angle in that direction is calculated. If two points at both ends of the three points are equidistant, it can be seen that the camera 103 faces the inspection target surface in the measurement direction.

In step S508, it is determined whether or not the camera 103 is facing the inspection target surface.
If the collimation angle is not 0 degrees, the camera 103 is not directly facing the inspection target surface (No in S508), so that a projection transformation matrix is calculated to perform projection transformation of the captured image and collimation angle compensation is performed (S509). , S510).
If the collimation angle is 0 degree, the camera 103 is directly facing the surface to be inspected (Yes in S508), so there is no need to compensate the collimation angle of the captured image, and the crack image extraction process (S511) is performed. .

In step S509, a projective transformation matrix is calculated by geometric calculation based on the collimation angle calculated in step S507.
In step S510, collimation angle compensation is performed by performing coordinate transformation of the captured image of the inspection target surface using the projection transformation matrix calculated in step S509. Thereby, the picked-up image of the surface to be inspected corresponding to the case where the image is taken in the directly-facing state can be obtained.

In step S511, image processing such as RGB color conversion (monochrome conversion), thinning (edge detection), and binarization of the captured image of the inspection target surface is performed, and the crack image is highlighted in an easily understandable manner. Specifically, the crack image on the gray concrete is difficult to see and the image may be blurred. Therefore, the crack image is displayed in an easy-to-understand manner by performing image processing.
Next, in step S512, the number of image pixels of the crack image corresponding to the crack width is obtained, and the size of the crack image is obtained by multiplying the size of the image pixel (element size of the image sensor of the camera 103). Then, the actual size of the crack width is calculated based on the imaging magnification determined from the distance between the lens of the camera 103 and the imaging device and the distance between the lens of the camera 103 and the inspection target surface.

  Next, a process for acquiring a projective transformation matrix by guide display (S513 to S516) will be described. By performing the processing after step S510 using the projective transformation matrix obtained in this processing, the crack width of the inspection target surface can be measured even when the camera 103 is swung. Steps S513 to S516 are the processes described in FIG.

First, in step S513, a captured image of the inspection target surface on which the crack width measurement is to be performed is displayed on the screen of the tablet unit 200, and a guide 410 is superimposed on the captured image (see FIG. 4).
Next, in conjunction with the operation of the stylus pen 400, a guide (any one of the guides 411, 412, and 413) deformed into a trapezoidal distortion corresponding to the change in the collimation angle is displayed (S514). Then, step S514 is repeated (not parallel to S515) until the captured image of the window frame having the rectangular shape of the inspection target surface (hereinafter referred to as a frame) and the hypotenuse of the trapezoid of the guide are parallel to each other. When the sides of the guide and the frame are in a parallel state (parallel of S515), the process proceeds to step S516.

In step S516, a projective transformation matrix is calculated from the four vertex coordinates of the guide 410 and the four vertex coordinates of the guide (guide 412 in FIG. 4) that matches the frame in step S515.
Then, the process proceeds to step S510, and the actual size of the crack width is calculated.

  According to the above processing flow, the actual size of the crack width can be measured. However, if the number of image pixels of the crack image corresponding to the crack length is obtained instead of the image pixel of the crack width in step S512, It is also possible to measure the actual length.

  The above processing can also be applied when the collimation direction of the camera 103 is tilted in the vertical direction. For this reason, it is possible to measure the crack width of the surface to be inspected at a high place from the ground with the crack width measuring system without the pole 101.

  In addition, as shown in the above processing flow, when the fluctuation of the distance to the inspection target surface is larger than a predetermined threshold, the collimation angle cannot be automatically detected because the camera and the distance meter are greatly shaken by wind or the like. Since the collimation angle is detected and the collimation angle is detected by the guide display, the crack width can be measured without unnecessary effort.

In the first embodiment described above, an example in which the crack width is obtained from a photographed image of a crack on the surface to be inspected has been described. Next, an example in which the crack width is obtained from a photographed image and a crack scale image will be described. The present embodiment can be implemented by the configuration of the crack width measuring system shown in FIG. 1 and the configuration of the control unit shown in FIG.
First, the outline of the measurement method of the present embodiment will be described with reference to FIGS.

  The crack scale is a scale for measuring the width of cracks generated on walls, floors, etc., and a plurality of straight lines with a thickness of about 0.05 mm to 2 mm are marked in units of 0.05 mm. In the conventional crack width measurement, this crack scale is applied to the crack, a line having the same width as the crack is visually determined, and the thickness of the line written on the crack scale is read to obtain the crack width. The present embodiment is a measurement method in which this measurement operation is performed by superimposing a crack scale image on the image of the inspection target surface.

FIG. 6 is a diagram illustrating an example of a crack scale image.
On one side of the crack scale image 600, a plurality of line drawings 601 having different thicknesses corresponding to lines applied to cracks on the crack scale are provided. In addition, a “scale ruler” 602 is provided on the opposite side so that the crack length can be measured.

  The original image information of the crack scale image 600 is stored as numerical information in a vector format so that the crack scale image 600 can be generated and displayed at an arbitrary magnification and rotation angle. As will be described in detail later, a crack scale image 600 is generated by obtaining the magnification from the imaging magnification, and collimation angle compensation is performed according to the deviation of the inspection target surface from the directly facing direction. Then, the crack scale image 600 is rotated in response to an operation instruction for lining a crack on the inspection target surface, and the crack scale image 600 is superimposed and displayed on the captured image of the inspection target surface.

Next, the superposition of the crack scale image 600 and the crack image will be described with reference to FIG.
FIG. 7 shows a screen of the tablet unit 200 that displays a photographed image of the inspection target surface imaged by the camera 103. It is assumed that a crack image to be measured is displayed in multi-value on the screen. In order to measure the crack width, a crack scale image 600 drawn and generated in accordance with the size of the object on the inspection target surface is superimposed and displayed.

  The crack scale image 600 is moved or rotated within the screen so that any line of the plurality of line drawings 601 having different thicknesses of the crack scale image 600 matches the crack to be measured. The horizontal or vertical movement of the crack scale image 600 is performed by a drag operation, and the crack scale image 600 is rotated by a two-point multi-touch rotation operation. By operating the crack scale image 600 as described above, the thickness of the line that matches the crack visually becomes the crack width.

The size (enlargement / reduction ratio) of the crack scale image 600 to be displayed is the imaging magnification determined from the distance between the lens of the camera 103 and the imaging device, the distance between the lens of the camera 103 and the inspection target surface, and the size of the display area. It depends on.
When a zoom operation of a captured image is performed by a pitch-in operation or a pitch-out operation, the crack scale image 600 is enlarged or reduced in accordance with the zoom operation.

  When the collimation direction of the camera 103 is not the facing direction, image distortion such as trapezoidal distortion occurs in the captured image. In the first embodiment, the collimation angle compensation for correcting the image distortion is performed by projective transformation of the image captured by the camera 103. However, in this embodiment, the crack scale image 600 is projectively transformed to produce the collimation angle. Compensate.

  By the way, the wider the angle of view of the camera 103 and the greater the deviation (collimation angle) from the directly-facing state, the difference in distance to the inspection target surface between the central part and the side part of the screen of the tablet unit 200. Becomes larger. For this reason, the distance from the camera 103 to the inspection target surface differs depending on the display location of the dragged crack scale image 600. In order to compensate for this, perspective compensation may be performed to change the size of the crack scale image 600 to be displayed according to the position of the crack scale image 600.

  As described above, in the generation of the crack scale image 600, image processing of enlargement / reduction, rotation, and projective transformation is performed. Since the original image information of the crack scale image 600 is stored as numerical information in the vector format, when performing enlargement / reduction, rotation, projective transformation processing on the crack format image information in the vector format, The crack scale image 600 is drawn and displayed. Thereby, a display error can be reduced.

  The collimation angle is obtained in the same manner as in the first embodiment. That is, since automatic detection cannot be performed when the variation in the distance to the inspection target surface is large, the collimation angle is detected by guide display, and when the variation is small, the collimation angle is automatically detected. For this reason, collimation angle detection can be performed without taking unnecessary effort.

  In the second embodiment, since cracks are visually identified by displaying the crack scale image 600 in an overlapping manner and obtaining the crack width, crack images are not extracted by image processing. For this reason, even cracks that are difficult to extract images, such as walls with significant dirt, can be measured with a low-performance device because the crack width can be measured if the cracks can be identified visually, and the application environment is increased. It becomes possible.

  Next, a crack width measurement flow of the crack width measurement system of Example 2 will be described with reference to FIG. In FIG. 8, steps S501 to S509 and steps S513 to S516 in the measurement flow described in FIG. 5 are common. That is, the same processing as in FIG. 5 is performed until the projection transformation matrix is obtained by automatic detection or the guide display described in FIG.

Hereinafter, processing unique to the present embodiment after step S801 will be described.
In step S801, the enlargement / reduction rate of the crack scale image 600 is calculated based on the imaging magnification determined from the distance between the lens of the camera 103 and the imaging device and the distance between the lens of the camera 103 and the inspection target surface.
If the camera 103 is not directly facing the inspection target surface in step S802, projective transformation of the crack scale image 600 is performed using the projective transformation matrix obtained in step S509 or step S615.

Next, the crack scale image 600 is converted based on dragging and rotational movement operation information of the crack scale image 600. At this time, it is good to perform perspective compensation according to the display position of the screen of the tablet unit 200 of the crack scale image 600.
Then, the crack scale image 600 subjected to the above-described conversion is superimposed and displayed on the captured image on the screen of the tablet unit 200 (S804).

Steps S803 and S804 above are repeated until the scale line matches the crack (S805). The coincidence between the crack and the scale line is determined by visual observation and is instructed by a tap operation of a numerical value button of a crack width (not shown).
Then, the tapped numerical button is set as the crack width, and the process ends (S806).

  Although not shown in particular, the “scale” 602 of the crack scale image 600 in FIG. 6 is photographed by performing conversion processing of enlargement / reduction, collimation angle compensation, rotation, and perspective compensation according to a drag / rotation operation instruction. It is also possible to measure the length of the crack by overlaying the image on the image and making a visual decision.

Here, the structure of the control part which performs said process is demonstrated based on FIG.
The compensation condition setting unit 207 calculates the enlargement / reduction ratio of the scale image in step S801 and performs projective transformation in step S802. Thereafter, the measurement image creation unit 204 generates a scale image 600 in conjunction with the drag / rotation movement according to the operation information from the input unit 202, and the measurement image composition unit 205 superimposes the image on the captured image for display. The image is displayed on the screen of the tablet unit 200 by the unit 203.

  According to this embodiment, the crack scale image stored as the numerical information in the vector format is converted in accordance with the inspection target surface and displayed superimposed on the photographed image, so that the display error of the crack scale image is reduced. In addition, the change in the visibility of the inspection target surface can be reduced. This makes it possible to measure the crack width and crack length with high accuracy even on a distant inspection target surface.

  The present invention is not limited to the embodiments described above, and includes various modifications. The above-described embodiment has been described in detail for easy understanding in the present invention, and is not necessarily limited to the one having all the configurations described.

DESCRIPTION OF SYMBOLS 110 Inspection apparatus control part 111 Camera control part 112 Distance sensor control part 113 Head / pole control part 114 Communication part 200 Tablet part 201 Communication part 202 Input part 2021 Automatic measurement and manual setting part 203 Display part 2031 Guide display control part 204 Measurement Image creation unit 205 Measurement image synthesis unit 206 Image acquisition unit 207 Compensation condition setting unit

Claims (7)

A crack width measurement system for measuring the width of a crack on a surface to be inspected,
An imaging unit that shoots an inspection target surface including a structure having a rectangular frame shape by tilting from a facing direction; and
A display unit that superimposes and displays a rectangular guide with a predetermined amount of trapezoidal distortion in accordance with an operation instruction on a captured image of the inspection target surface captured by the imaging unit;
A distance sensor for measuring a distance between the imaging unit and an inspection target surface imaged by the imaging unit;
When the frame shape in the captured image of the surface to be inspected displayed on the display unit and the side of the guide that has been distorted by the predetermined amount of trapezoid are in a parallel state, the surface to be inspected is tilted from the facing direction. A measurement image creation unit that performs image conversion for collimation angle compensation that compensates for image distortion due to a certain collimation angle, and
A crack width measuring system for measuring a crack width of a crack on a surface to be inspected displayed on the display unit. In the crack width measuring system according to claim 1,
The measurement image creating unit is a vertex of the rectangular guide when the frame shape of the captured image of the structure displayed on the display unit and the side of the guide that is trapezoidally distorted by the predetermined amount are in a parallel state. A crack width measurement system characterized in that a projection transformation matrix is obtained based on coordinates and a vertex coordinate of a guide having a predetermined amount of trapezoidal distortion, and collimation angle compensation is performed by performing image transformation using the projection transformation matrix. In the crack width measuring system according to claim 1 or 2,
The display unit is characterized by changing a trapezoidal distortion amount of the rectangular guide according to an operation instruction so as to correspond to a trapezoidal distortion due to a collimation angle representing an inclination of the surface to be inspected from a facing direction. Crack width measurement system. In the crack width measuring system according to any one of claims 1 to 3,
The measurement image creation unit
When the variation in the distance between the imaging unit and the inspection target surface is equal to or greater than a predetermined threshold, the projection transformation matrix is obtained by the guide displayed by the display unit, and the collimation angle of the image is compensated.
When the variation in the distance between the imaging unit and the inspection target surface is less than a predetermined threshold, the projection transformation matrix is calculated by obtaining the collimation angle from the value of the distance between the imaging unit and the inspection target surface in at least three directions. A crack width measurement system characterized in that collimation angle compensation is performed. In the crack width measuring system according to any one of claims 1 to 4,
The measurement image creation unit compensates the collimation angle of the captured image, and obtains a converted image corresponding to the captured image in which the imaging unit captures the inspection target surface from the directly facing direction,
The display unit displays the converted image,
A crack width measuring system characterized in that the number of pixels corresponding to a crack in the converted image is obtained and the crack width is measured. In the crack width measuring system according to any one of claims 1 to 4,
The display unit superimposes and displays a photographed image of the inspection target surface photographed by the imaging unit and a crack scale image obtained by projective transformation based on crack scale information recorded in a vector format. Crack width measurement system. In the crack width measuring system according to claim 6,
Based on the crack scale information, the measurement image creation unit performs image conversion for enlargement / reduction by the imaging magnification of the imaging unit, performs projective conversion for the collimation angle compensation, and moves the crack scale image Alternatively, the crack width measurement system is characterized in that the crack scale image is generated by performing image conversion based on rotation operation information.

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