JP3067652B2 - Concrete crack measuring method and measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the distribution and width of cracks in concrete such as walls of a building, and a measuring device used for the method.

[0002]

2. Description of the Related Art The surface of a concrete building deteriorates with time, and among these surface deteriorations, "cracks" are important inspection items for diagnosing soundness. Therefore,
It is important to accurately measure the distribution range and width and to grasp the state change over time.

Conventionally, as means for measuring the distribution range and width of a crack, an operator sketches a concrete surface and directly applies a crack scale to the crack to measure the width of the crack.

However, according to this method, a high level of skill is required for the observer, and it is difficult to accurately sketch the position and width of the crack without individual differences. In addition, workability is not good because it takes a long time to work on site. Further, depending on the location of the concrete building to be measured, work facilities such as large-scale scaffold erection are required, and work is dangerous particularly at high places.

Therefore, in recent years, proposals have been made to take a photograph of the surface to be inspected once, and to examine the state of the crack by applying image processing, analysis, and the like to the photograph, and practical use thereof has been studied.

[0006]

Since the size of the actual inspected surface is different from the size of the inspected surface shown in the photograph, a scale (ruler) or the like is photographed together at the time of photographing, and the photograph is taken from the photographed scale. Is calculated, and numerical values such as length and width are calculated based on the scale. Therefore, it is necessary to attach a standard length of scale or the like to the surface to be surveyed. If the surface to be surveyed is at a high place, a scaffold stand is still required, and workability has been greatly improved. Absent.

Further, if a photograph is taken obliquely from the surface to be inspected, the distribution and width of the cracks cannot be known accurately, so that it is necessary to take the image directly in front of the surface to be inspected. However, it is difficult to take a picture directly from the front, and the measurement error tends to increase. Also, in some places, it is difficult to take a picture directly in front of the user.

Therefore, in a method of measuring cracks in concrete by photographing, there is a need for a method and an apparatus therefor that do not have to go to the surface to be inspected and can accurately measure without directly facing the surface to be inspected. ing.

[0009]

According to the method for measuring cracks in concrete of the present invention, at least three measurement points (S1), (S2) and (S3) on the surface to be inspected (A) are measured from a camera (1). The distance to each measurement point, the horizontal angle and the vertical angle are measured and calculated to calculate the inclination angle of the surveyed surface (A) with respect to the optical axis of the camera (1). Multiple inspected surfaces including
The photograph of (A) is taken, the information of the photograph is taken into the arithmetic unit (12), and the distribution of the cracks is corrected by an arithmetic processing so that the surface to be inspected (A) is a continuous image viewed directly from the front. together determine the state, a distance on the predetermined distance and the actual surveyed surface corresponding to that of the corrected image (a) above
Distance from camera (1) to each measurement point (S1), (S2), (S3) and
Obtain the scale width from the distance calculated based on the inclination angle of the surveyed surface (A), calculate the width of the crack, and display the distribution state and the width of the crack on the surveyed surface (A). Features.

[0010] Alternatively, three measurement points (S1) on the surveyed surface (A),
Measurement points (S1), (S2), (S2), (S3) from camera (1)
The distance to (S3), the horizontal angle and the vertical angle are measured and calculated, and the inclination angle of the inspection target surface (A) with respect to the optical axis of the camera (1) is obtained.
The photographing center (S1) of one photograph is determined, the distance from the camera (1), the horizontal angle and the vertical angle with respect to the optical axis of the camera are obtained, and the photographing centers (P2), (P3), (P Calculate the horizontal angle and vertical angle of (P4), and take a picture by pointing the camera (1) according to the calculation result.A plurality of surveyed surfaces (A) including overlapping parts (C) Photos (B1), (B2),
The images of (B3) and (B4) are taken, and the information of the photograph is taken into the arithmetic unit (12), and the distribution of cracks is corrected by an arithmetic process so that the inspected surface is a continuous image viewed directly from the front. The state is calculated, and the distance between adjacent photo centers on the corrected image and the corresponding distance on the actual surveyed surface (A)
The distance from the camera to each measurement point and the survey
Calculate the scale from the distance calculated based on the inclination angle of the surface to determine the width of the crack, and use the output device to
It is characterized in that a phase diagram showing the distribution state of cracks and the width of cracks in (A) is output.

Alternatively, three measurement points (S1) on the surveyed surface (A),
For each of (S2) and (S3), an optical distance meter (5) having an optical axis parallel to the optical axis of the camera (1) is used to measure each point from the optical distance meter (5).
Measure the distance to (S1), (S2), (S3) and the horizontal and vertical angles,
The measurement result is calculated using a trigonometric function by a calculation device (12) to determine the inclination angle of the surveyed surface (A) with respect to the optical axis of the camera (1), and the photographing center (P1) of one photograph is determined. , The distance from the camera (1), the horizontal angle and the vertical angle with respect to the optical axis of the camera (1) are obtained, and the photographing centers (P2), (P
Calculate the horizontal angle and vertical angle of (3), (P4), and calculate each shooting center (P1), (P
2), (P3), (P4) Point the camera (1) at the camera and take a picture. The obtained information is introduced into the arithmetic unit (12), and the arithmetic processing is performed to correct the image to be a continuous image viewed directly from the front of the inspected surface, to obtain the distribution state of the cracks, and to determine the adjacent state on the corrected image. The distance between the center of the photograph to be measured and the corresponding distance on the surveyed surface (A), and each measurement point (S
1), (S2), (S3) and the inclination angle of the surveyed surface
The scale width is calculated from the distance calculated from the distance, and the width of the crack at the specified position is obtained.
It is characterized in that a state diagram showing the distribution state of the cracks and the width of the cracks at the designated location in (A) is output.

The concrete crack measuring apparatus according to the present invention comprises a camera (1) and an optical distance arranged at a fixed distance from the camera (1) so as to have an optical axis always parallel to the optical axis of the camera (1). Encoder (5) and encoder that measures the rotation angle of camera (1)
(3), (4), encoders (6), (7) for measuring the rotation angle of the optical rangefinder (5), and an arithmetic unit (12) for information taken by the camera (1)
Reading device (13) and optical distance meter (5)
And the encoder (3), (4), (6), on the basis of the information read by the information obtained from (7) reader (13)
The distance between the camera (1) and the surveyed surface (A) and the tilt of the surveyed surface (A)
An arithmetic unit (12) capable of calculating an oblique angle and calculating a scale factor based on the calculated value is provided.

A camera (1), an optical distance meter (5) arranged at a fixed distance from the camera (1) so as to always have an optical axis parallel to the optical axis of the camera (1), and a camera (1); Encoders (3) and (4) for measuring the rotation angle of (), encoders (6) and (7) for measuring the rotation angle of the optical distance meter (5), and the optical distance meter (5) and the encoder
(3), (4), (6) , a computing device (12) for processing the information obtained from (7), and a reading device for reading information taken by the camera (1) to the computing device An arithmetic unit capable of arithmetically processing information read by the reading unit ,
(1) Distance between the surveyed surface (A) and the inclination angle of the surveyed surface (A)
Is calculated, and the scale factor is calculated based on the calculated value .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to preferred embodiments. [Measurement of Distance to Investigated Surface and Inclination of Investigated Surface] FIG. 1 is a diagram showing how the distance to the inspected surface and the inclination of the inspected surface are measured. In the figure, (A) is a surface to be inspected, (1) is a camera, and (2) is a mechanism for rotating the camera (although illustrated in a simplified manner in the figure). The camera is usually installed horizontally.

[0015] An optical distance meter mounted adjacent to the camera (1) and having an optical axis parallel to the optical axis of the camera.
The distance between (1) and any three points (S1), (S2), and (S3) on the surface to be inspected is measured. Since three points are measured, the tilt angle of the surveyed surface (A), that is, the surveyed surface (A) with respect to the optical axis of the camera (1)
Can be measured in the horizontal direction and the vertical angle (elevation angle or depression angle with respect to the horizontal plane).

FIG. 3 is a diagram showing an outline of the configuration of the measuring device. (1) is a camera that takes pictures, (3) is a vertical rotary index that rotates the camera in the vertical direction,
(4) is a horizontal rotary index for rotating the camera in the horizontal direction. (5) is an optical range finder, which is used to determine the distance from the camera to the surface to be inspected. (6)
Is a rotary encoder that measures the number of rotations of the gear of the rotary index when the camera is rotated. (7) is a mirror rotation angle encoder, which is used to measure the mirror angle of the optical distance meter (5). (8) is a connector box, and (9) is a 3-axis 24-bit counter for converting signals sent from each encoder into data for processing by a personal computer. (11) is a power storage area serving as a power supply, and (10) is a DA converter. (12) is a personal computer as an arithmetic device for performing various calculations. (13) is a reading device such as a scanner, and (14) is an output device such as a printer and a plotter.

In FIG. 1, for convenience of explanation, the distance between the camera and the measurement point (S1), (S2), (S3) on the surface to be inspected is directly measured. (5) and camera (1)
Are located slightly apart and the rotation axis of the measuring device is
Since this is different from the point where the image on the film surface is formed in (1), the distance and angle from the camera (1) cannot be accurately obtained as it is. Since the distance between the optical rangefinder (5) and the camera (1) is always constant, and the optical axes of both are always parallel, the encoder
A camera (12) based on the angle data obtained from (6) and (7) and the distance data obtained from the optical distance meter (5), which is corrected using a trigonometric function on a personal computer (12).
A measurement value based on (1) can be obtained. As a result, the distance between the three measurement points (S1), (S2), (S3) on the inspected surface (A) and the image connecting the camera (1) on the film and the optical axis of the camera The horizontal angle and the vertical angle of the plane (A) can be obtained.

[Specifying the Center Point of a Photo] FIG. 2 is a view showing a state at the time of photographing, and FIG. An arbitrary point (P ₁ ) is determined as the photographing center of one photograph (B1) serving as a reference, the distance, the horizontal angle and the vertical angle are measured, and the other three points are determined by the personal computer (12) based on the data. Photos (B2), (B3), (B
A horizontal angle and a vertical angle for directing the camera to the photographing center (P ₂ , P ₃ , P ₄ ) in ₄ ) are calculated. In this embodiment, the photographing center (P) is set such that four photographs are photographed in a “field-shaped” (two vertically and horizontally arranged) slightly overlapping each other.
₂ , P ₃ , P ₄ ).

Then, based on the calculation result, the camera (1) is directed in each direction to photograph each photograph (a total of four photographs).
Defining an imaging center of each photo _{(P 1, P 2, P} 3, P 4), if we lined by photographing as the point becomes the actual imaging center,
You can get a rice-shaped photo with some overlap. (C) in the figure is an overlap portion where the pictures overlap.

Here, the photographs are taken so as to overlap each other in order to determine the scale of the photographs in the subsequent process and to prevent the occurrence of “missing” parts that cannot be investigated between the photographs. Therefore, the overlapping part
The center point (P ₂ , P ₃ , P ₄ ) of the photograph is calculated so that a large area photograph can be efficiently taken by minimizing (C).

[Reading and Correction] Each photograph is taken into a personal computer (12) by a reading device (13) such as a scanner, joined on a screen, and arranged in a continuous “field” shape. Note that the photos may be connected in the form of a "field" before being imported to the personal computer (12).

The photograph taken is oblique (other than directly in front)
If the photograph is taken from above, the position and width of the crack will be inaccurate due to the perspective of the photograph. Therefore, by performing an arithmetic process using the software of the personal computer (12) in a manner similar to that taken from the front, the state of the surveyed surface (A) viewed from the front is displayed on the screen of the personal computer (12). To do.

[Reading and Drawing] A cracked portion is read from the corrected screen. At this time, the darkened part was recognized as cracks by binarization processing, etc., but if the joints or dirt on the surface of the concrete were erroneously recognized as cracks, it was displayed on the screen. And conversely, it is also possible to correct a part which is not recognized even though it is actually a crack.

Further, when it is difficult to automatically recognize the crack from the screen because the contrast between the surface of the surface to be inspected and the crack is abnormally small, etc., it is preferable to trace the screen with a mouse or a pen input device. To enter the location of the crack.

Next, the width of the crack at the designated location is displayed numerically. The distance between the centers of the photographs is set as a reference dimension, and the scale is calculated by comparing with the corresponding actual reference dimension (for example, between P _{1 and} P ₄ ) of the surface to be inspected, and the number of picture elements in the width direction of the crack portion on the screen is calculated. The actual crack width can be calculated from the scale factor. Similarly, the length of the crack may be displayed numerically.

Based on the information obtained above, an output device (14) such as a printer or plotter can output a drawing showing the distribution of cracks on the surface to be inspected and the width of the cracks at the designated location. Of course, the information can be stored in a storage medium such as an FD.

For the same crack on the surface to be inspected, the distance between the measuring device and the surface to be inspected (A) is 20 m, and the angle between the optical axis of the camera (1) and the surface to be inspected (A) is 90 ° (directly in front). And right 6
Table 1 shows measurement values obtained by processing a photograph taken from 0 ° and actual measurement values measured by a measurer using a crack scale when an operator goes to the inspected surface (A).

[0028]

[Table 1]

As is clear from Table 1, although there is a slight difference in the measurement results, considering that there is also a measurement error in the actually measured values, it can be said that the measurement was performed with very high accuracy, and the practicality was sufficiently high. I found it.

In the present embodiment, four photographs are arranged in a "field shape", but two or three photographs may be photographed so as to partially overlap each other, or a larger area may be taken. When examining a plurality of surfaces to be examined, five or more photographs may be arranged like a grid.

When the surface to be inspected is not a plane but has a step or a bend, it is advisable to inspect the surface separately.

Further, in the above-described embodiment, information is taken into the personal computer by taking a photograph using a normal camera as a camera and developing the photograph, but the information is directly taken into the personal computer by using a CCD camera as a camera. May be. In that case, the time required for developing the photograph can be eliminated.

As long as the range finder can be used, other types, such as those based on radio ranging, ultrasonic ranging, and optical ranging, may be used.

In the above embodiment, the same personal computer (12) is used as the arithmetic unit used for image processing and the arithmetic unit used for calculating the distance and the angle. However, different arithmetic units may be used.
For example, as shown in FIG. 4, a small personal computer (12), which is easy to carry, is taken to the site to take a picture, and a computing device such as a large office computer (15) for image processing, a scanner, etc. Reading devices (13) and output devices such as printers (14)
If it is placed in a company, office, or the like, the base material to be carried is small and the weight is reduced, so that the mobility is improved.

[0035]

As described above, in the method of measuring the state of cracks in concrete by photographing according to the present invention, it is not necessary to go to the surface to be inspected, and the measurement can be accurately performed without facing directly from the surface to be inspected. A possible method and an apparatus therefor have been provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state of measuring an angle and a distance of a surface to be inspected.

FIG. 2 is a view showing a state of photographing a surface to be inspected.

FIG. 3 is a diagram illustrating an outline of a configuration of a measuring apparatus according to an embodiment.

FIG. 4 is a diagram showing an outline of a configuration of a measuring apparatus according to an embodiment.

[Explanation of symbols]

 (1) Camera (3) Vertical rotary index (4) Horizontal rotary index (5) Optical rangefinder (6) Rotary encoder (7) Mirror rotation angle encoder (12) Personal computer (computing device) (13) Scanner (reading device) (15) Office computer (arithmetic unit)

Continued on the front page. (72) Inventor Tsuneo Shioya 5-14-10 Nishitenma, Kita-ku, Osaka Kinki Concrete Industry Co., Ltd. (72) Inventor Matsu ▲ Saki ▼ Ryoichi 5-14-10 Nishitenma, Kita-ku, Osaka Kinki (56) References JP-A-62-288685 (JP, A) JP-A-3-57910 (JP, A) JP-A-5-122606 (JP, A) JP-A-5-100335 (JP JP, A) JP-A-2-178646 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 102 G01N 21/88, 33/38 G06T 1 / 00

Claims (5)

(57) [Claims] At least three measurement points on a surface to be inspected are measured and calculated from a distance from a camera to each measurement point, a horizontal angle and a vertical angle, and an inclination angle of the surface to be inspected with respect to an optical axis of the camera is obtained. A plurality of photographs of the surface to be inspected including a part that partially overlaps are taken, and the information of the photograph is taken into an arithmetic unit so that a continuous image is obtained when the surface to be inspected is viewed directly from the front by arithmetic processing. In addition to calculating the distribution of cracks, the distance from the camera to each measurement point is the predetermined distance on the corrected image and the corresponding distance on the surface to be inspected.
Calculating the width of the cracks by calculating the scale from the distance of the surface and the distance calculated based on the inclination angle of the surface to be inspected, and displaying the distribution state of the cracks and the width of the cracks on the surface to be inspected. A crack measuring method for concrete characterized by the following. And measuring and calculating the distance from the camera to each of the measurement points, the horizontal angle and the vertical angle with respect to three measurement points on the inspection surface, and calculating the inclination angle of the inspection surface with respect to the optical axis of the camera. Determine the shooting center of one photo, the distance from the camera,
Calculate the horizontal angle and vertical angle with respect to the optical axis of the camera, calculate the horizontal angle and vertical angle of the shooting center of other photos based on it, and aim at the camera according to the calculation result and shoot the photo to partially overlap Takes a plurality of photographs of the inspected surface including the part to be inspected, incorporates the information of the photograph into the arithmetic unit, and performs arithmetic processing to correct the inspected surface so that it becomes a continuous image viewed directly from the front and cracks together with obtaining the distribution state, and photographs the distance between the centers of adjacent on the corrected image, or the actual a distance on the survey surface the camera corresponding thereto
From each measurement point and the inclination angle of the surveyed surface
Crack measurement, characterized by calculating the scale width from the calculated distance and calculating the width of the crack, and outputting a state diagram showing the distribution state and width of the crack on the surface to be inspected by an output device. Method. 3. The distance, horizontal angle, and vertical angle from the optical distance meter to each of the three measurement points on the surface to be inspected using an optical distance meter having an optical axis parallel to the optical axis of the camera. Is calculated by the arithmetic unit using a trigonometric function to obtain the inclination angle of the surface to be inspected with respect to the optical axis of the camera. Calculate the horizontal angle and the vertical angle with respect to the optical axis of, calculate the horizontal angle and the vertical angle of the shooting center of the other three pictures based on the horizontal and vertical angles, and shoot the picture by directing the camera to each shooting center according to the calculation result Takes four photos in a "field-shaped" array, including overlapping parts,
The information of the photograph is taken into the arithmetic unit, and the arithmetic processing is performed to correct the image to be a continuous image of the surface to be inspected as viewed directly from the front, to determine the distribution of cracks, and to determine the adjacent photo on the corrected image. a center-to-center distance, or an actual distance on the survey surface the camera corresponding thereto
From each measurement point and the inclination angle of the surveyed surface
Calculate the scale ratio from the calculated distance to calculate the width of the crack at the specified location, and output a state diagram showing the distribution of cracks on the surveyed surface and the width of the crack at the specified location using the output device. Characteristic method for measuring cracks in concrete. 4. A camera, an optical distance meter arranged at a fixed distance from the camera so as to have an optical axis always parallel to the optical axis of the camera, and an encoder for measuring a rotation angle of the camera;
An encoder for measuring the rotation angle of the optical distance meter, a reading device for reading information taken by a camera to an arithmetic device, and information obtained from the optical distance meter and the encoder and based on information read by the reading device. Camera
Calculate the distance between the object and the surveyed surface and the inclination angle of the surveyed surface.
An arithmetic device capable of performing an arithmetic process for calculating a scale factor based on the calculated value of (1) is provided. 5. A camera, an optical distance meter arranged at a fixed distance from the camera so as to have an optical axis always parallel to the optical axis of the camera, and an encoder for measuring a rotation angle of the camera.
An encoder for measuring the rotation angle of the optical distance meter, an arithmetic device for arithmetically processing information obtained from the optical distance meter and the encoder, a reading device for reading information taken by a camera into the arithmetic device, and the reading device Computation unit that computes the information read from the computer, calculates the distance between the camera and the surface to be inspected and the inclination angle of the surface to be inspected
A concrete crack measuring device, wherein a scale factor is calculated based on the calculated value .