JPH0718696B2 - Automatic crack measuring device - Google Patents

Description

The present invention relates to a crack automatic measuring device suitable for use in diagnosing deterioration of concrete structures in the field of civil engineering and construction.

[Conventional technology]

The crack investigation is a basic investigation item in the deterioration diagnosis of concrete structures.

Conventionally, this crack inspection has been carried out by a human being sufficiently close to the inspection position and visually observing, and marking and sketching the crack or taking a photograph.

[Problems to be solved by the invention]

However, in the conventional crack investigation as described above, it takes a considerable time from the investigation plan to the report, and especially when the investigation object is at a high place, materials such as work scaffolds are required, which requires a great deal of research labor. Will be required. Furthermore, because the accuracy of measuring the distribution and width of cracks, the number of measuring points and the number of them differ depending on the level of skill and individual differences among investigators, the method of saving data for crack investigations could not be unified, and data saving was incomplete. Comparison with the results of the crack investigation conducted in
It is difficult to examine the time series. In addition, current image input
The processing / recording device has a problem that the storage capacity required for data recording is enormous and it cannot be put to practical use.

The present invention solves the above problems, and an object thereof is to provide an automatic crack measuring device capable of performing crack inspection with a simple operation and obtaining survey data with constant accuracy without individual differences. .

[Means for solving problems]

Therefore, the present invention is a crack automatic measuring device for measuring cracks by processing image data obtained by photographing a structure, and a binarizing means for binarizing the image data by setting a threshold value, Thinning processing means for obtaining a centerline of an image group in which binarized data are connected, vectorization means for vectorizing the centerline, and differentiation of image data with respect to a direction perpendicular to the vectorized centerline. It is characterized in that a crack detecting means for detecting crack information of the structure by comparison with the take threshold value is provided.

[Action]

In the automatic crack measuring device of the present invention, the light and dark image data obtained by imaging the structure is binarized, and the center of the cracked portion is found by finding the center of the connected pixel group by the thinning processing means. To be Then, the vectorizing means vectorizes the center line of the cracked portion, and the crack detecting means detects the crack width and other crack information in vector units.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of one embodiment of an automatic crack measuring device of the present invention, FIG. 2 is a diagram showing a specific functional configuration example of an image data processing device, and FIG. 3 is a diagram showing an example of image data. FIG. 4 is a diagram showing an example of analysis data by the image data processing device. In the figure, 1 is an imaging unit, 2 is an input image control unit, 3
CRT, 4 data processor, 5 magnetic tape, 6 floppy disk, 7 printer, 8 magnetic disk,
Reference numeral 11 is a binarization processing unit, 12 is a thinning processing unit, 13 is a vectorization processing unit, 14 is a crack width detection unit, 15 is a vector length / width correction unit, and 16 is a crack image data output unit.

In FIG. 1, the image pickup unit 1 picks up an image of a crack such as a concrete structure in place of human eyes, for example, a CCD (C
harged Coupled Device) such as cameras and television cameras. The input image control unit 2 captures the image obtained by the image capturing unit 1 into the data processing device 4 and the CRT 3
It controls the image pickup unit 1 and the CRT 3 for monitor for display on the screen. Although not shown, the position movement for imaging is performed by a position movement device according to the shape of the survey target, and image position data information is input from the position movement device. In order to assist the normal operation of the position moving device and the image pickup unit 1, one operator may be arranged. Data processing device 4
Is composed of a personal computer or a dedicated processor, and when image data is input from the image pickup unit 1 through the input image control unit 4, the crack information such as the position of the crack and the width of the crack is extracted from the image data. It is a thing. The external storage device that stores the crack information extracted by the data processing device 4 together with the image position data information is the magnetic tape 5, the floppy disk 6, or the magnetic disk 8, and the printer 7 prints out. The crack information and the image position data information may be transmitted to a large computer by using a dedicated line or a telephone line (not shown).

Next, crack measurement by the automatic crack measurement device shown in FIG. 1 will be described. First, the image information of the subject is acquired by the image pickup unit 1.
The image is captured as a digital image signal by the CRT 3, the captured image is visually confirmed by the CRT 3, and the digital image signal is input to the data processing device 4. When a CCD camera is used as the image pickup unit 1, a two-dimensional or three-dimensional subject is photoelectrically converted by a CCD sensor in the photosensitive unit through an optical lens to output subject image information as a digital signal (luminance gradation). Will be done.

For example, a CCD with 2048 charge-coupled devices arranged horizontally
When a CCD camera of the type in which a line image type solid-state image sensor is mechanically driven in the vertical direction by 3000 steps is used, a 2000 / horizontal 3000 image division can capture a subject image. Then, in each pixel, the image information is decomposed into brightness gradations of 256 gradations (8 bits) by color gradation (black and white), converted into digital signals, and sequentially processed by the data processing device 4.
To enter.

In the data processing device 4, after setting a certain threshold value for each pixel of the image data converted into a digital signal and binarizing it, thinning is performed to obtain a crack center line. Then, vectorization is performed by line tracing, and crack information such as the position of the crack and the width of the crack is extracted. The data obtained by such image processing is recorded in a storage device or transmitted to a large-sized computer using a dedicated line or a telephone line. Then, a large computer is constructed from the recorded or transmitted data to construct an entire image, which is compared with the design information to perform crack analysis.

Next, an example of the processing of image data by the data processing device 4 will be described with reference to FIGS. When image data as shown in FIG. 3 (a) is input to the data processing apparatus, first, the binarization processing unit 11 outputs image data digitized to a density of 256 gradations (0 to 255). The threshold value is classified into two categories, "1" (black) and "0" (white).

Subsequently, the thinning processing unit 12 identifies the removable points while retaining the end point storage conditions and the number of connections, and degenerates the final point into a series of 8 connected points. In this process, isolated points (noise) such as non-linear stains degenerate into points. Next, the center line of the cracked portion is obtained and thinning is performed. Although various methods are already known for such a thinning process, the present invention is not limited to the specific contents of the thinning process, and a conventional method is appropriately selected and applied. Of course, it is okay.

After that, the vectorization processing unit 13 detects the bifurcation and the end point while line tracing the line of the central portion of the thinned crack, and determines the virtual vector end point where the virtual vector is within n pixels from the trace line. By obtaining and repeating this, the center of the crack is represented by a vector group (polygonal line) with the coordinates of the starting point (X1, Y1) and the coordinates of the ending point (X2, Y2). This makes it possible to obtain direction information that can be understood by a machine (computer) or a human being in a crack image that has no direction information as a pattern.
Note that needle-shaped noise can be further removed by removing the short vector having no connecting point.

When the vector data is obtained, the crack width detection unit 14 finds the crack width W by comparing the vector data with the input image (raw data) shown in FIG. This crack width can be detected by taking the differential of the input image with respect to the direction perpendicular to each vector and comparing the value with a threshold value.

The vector length / width correction unit 15 compares the vectors, correlates with the raw data, corrects the missing portion in the binarization stage, and joins the cut vectors. For example, the value of the raw data on the extension line of the vector in the middle of the cut vector is traced to join the cut vectors.

The crack image data output unit 16 draws a line from the vector data, converts it into a crack image as shown in FIG. 4 (b), and outputs it.

FIG. 4 is a diagram showing an output example of analysis data of crack information, FIG. 4 (a) is an output example of a crack image based on vector data, and FIG. 4 (b) is a statistics of crack length with respect to crack width. A display example processed and graphed, FIG. 4 (c) is an output example in which a crack length for an angle formed by an arbitrary coordinate axis and a crack is statistically processed and graphed, and FIG. 4 (d) is for position coordinate in the longitudinal direction. It is an output example in which the crack length is statistically processed and graphed. It is appropriate to perform such statistical processing and display by a large-scale computer because it is necessary to input data of the structure to be surveyed, but it is also possible to display each image by the image data processing device.

FIG. 5 is a diagram showing a state of use of the automatic crack measuring device according to the present invention when measuring cracks in an underground line, and FIG. 6 is an automatic crack measurement according to the present invention when measuring cracks in a bridge. It is a figure which shows the mode of the usage state of an apparatus. In the figure, 21 indicates an image input device (imaging unit), 22 indicates a main body device, and the main body device 22 is an input image control unit, a CRR 3 for a monitor, a data processing device (computer) in FIG.
4, a storage device such as a magnetic tape 5, a floppy disk 6, a magnetic disk 8 and the like, and a printer 7 are incorporated, and they are mounted on a trolley having wheels so that they can be easily moved. The image input device 22 is extendable and retractable.
Image of the wall surface etc.
Send to. Therefore, the desired concrete structure wall surface can be imaged by the image input device 22 while moving the carriage,
The image data is sent to the main body device 21 and the above-described processing is performed to extract the crack information.

The present invention can be modified in various ways and is not limited to the above-mentioned embodiments.

〔The invention's effect〕

As is clear from the above description, according to the present invention, an image of a portion to be investigated is obtained by using the image input device, and a predetermined process is performed from this image by the image data processing device to obtain necessary crack information. Since it is extracted, a consistent crack distribution and width measurement accuracy can be secured, and differences among investigators are eliminated. Moreover, only one operator is required, which can reduce the research labor and the research period. Also,
Although a position moving device according to the survey target is required, materials such as scaffolding are unnecessary, and it is free from the danger of working at height. Further, a magnetic tape, a laser disk, or the like can be used for data storage, and a storage capacity can be secured as needed in a unified manner.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of one embodiment of an automatic crack measuring device of the present invention, FIG. 2 is a diagram showing a specific functional configuration example of an image data processing device, and FIG. 3 is a diagram showing an example of image data. FIG. 4 is a diagram showing an example of analysis data by an image data processing device, and FIG. 5 is a diagram showing a state of use of an automatic crack measuring device according to the present invention when measuring a crack in an underground line, FIG. FIG. 6 is a diagram showing a state of use of the automatic crack measuring device according to the present invention when measuring cracks in a bridge. 1 ... Imaging unit, 2 ... Input image control unit, 3 ... CRT, 4 ... Data processing device (computer), 5 ... Magnetic tape, 6 ... Floppy disk, 7 ... Printer, 8 ... Magnetic disk,
11 ... Binarization processing unit, 12 ... Thinning processing unit, 13 ... Vectorization processing unit, 14 ... Crack width detection unit, 15 ... Vector length / width correction unit, 16 ... Crack image data output unit.

Claims (1)

[Claims] 1. A crack automatic measuring device for measuring cracks by processing image data obtained by photographing a structure, which comprises binarizing means for binarizing the image data by setting a threshold value, and 2. Thinning processing means for obtaining the center line of the pixel group connected with the binarized data, vectorization means for vectorizing the center line, and differentiating the image data with respect to a direction perpendicular to the vectorized center line. An automatic crack measuring device comprising a crack detecting means for detecting crack information of a structure by comparison with a threshold value.