JPH01182714A - Automatic measuring apparatus of crack - Google Patents

Abstract

PURPOSE:To secure the measuring accuracy of the distribution and the widths of cracks constantly all the time and to avoid difference in accuracy due to individual inspectors, by performing specified processing for image of a part to be inspected, and obtaining the required crack data. CONSTITUTION:The image data of an object are obtained as a digital image signal with an image sensing part 1 and an input image control part 2. The image is visually recognized with CRT 3. The signal is inputted into a data processing device 4. A threshold value is set for each picture element of the digitized image data, and binary coding is performed. This lines are provided and the central line of cracks is obtained. Vector is obtained by the tracing of the line. Thus the data such as the positions and the widths of the cracks are obtained. The data, which are obtained by processing the image in this way, are stored in a memory device or transmitted to a large electronic computer through a leased circuit or a telephone circuit. The entire image is constituted with the data and compared with design data. Thus the cracks are analyzed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic crack measuring device suitable for use in diagnosing deterioration of concrete structures in the field of civil engineering and construction.

[Conventional technology]

Crack investigation is a basic investigation item in deterioration diagnosis of concrete structures.

Conventionally, this crack investigation has been carried out by a person getting close enough to the investigation location, visually observing it, and marking and sketching or photographing the crack.

[Problem to be solved by the invention]

However, in the conventional crack investigation as described above, it takes a considerable amount of time from the investigation plan to the report, and especially when the investigation target is at a high place, materials such as work scaffolding are required, and a large amount of investigation labor is required. is required. Furthermore, because the accuracy of measuring the distribution and width of cracks, as well as the number and locations of measurements, differ depending on the skill level of the surveyor and individual differences, the data storage method for crack survey results cannot be unified, and data storage is incomplete and Comparison with the crack investigation results conducted in
It is difficult to examine chronologically. In addition, the current image input
Processing/recording devices have problems such as the enormous storage capacity required for data recording, which makes them impractical.

The present invention solves the above-mentioned problems, and aims to provide an automatic crack measuring device that can investigate cracks with simple operations and can obtain survey data with constant accuracy without individual differences. .

[Means to solve the problem]

To this end, the automatic crack measuring device of the present invention is an automatic crack measuring device that measures cracks by processing image data obtained by imaging a structure, and binarizes the image data by setting a darkness value. binarization means for degenerating each figure of the binarized data toward the center point; and noise removal for determining and removing noise by superimposing the figure on the center point determined by the degeneracy processing means. means, thinning processing means for determining a center line of a connected pixel group of binarized data after noise removal, vectorization means for vectorizing the center line, and crack information from the vectorized center line and image data. The present invention is characterized in that it includes a crack detection means for detecting cracks.

[Effect]

The automatic crack measurement device of the present invention binarizes the bright and dark image data obtained by imaging a structure, and degenerates the figure to find the center point of the figure, so the size of the figure from this center point can be calculated. By examining the point-like noise, it is possible to determine and remove it using a simple algorithm. Then, the center line of the cracked portion is determined by determining the center line with a line width of 1 using the thinning processing means from the binary image after noise removal. This center line is vectorized by the vectorization means, and the crack width and other crack information in vector units are detected by the crack detection means.

〔Example〕

Examples will be described below with reference to the drawings.

Fig. 1 is a diagram showing the configuration of an embodiment of the automatic crack measuring device of the present invention, Fig. 2 is a diagram showing a specific functional configuration example of the 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, l is an imaging unit, 2 is an input image control unit, and 3
is a CRT, 4 is a data processing device, 5 is a magnetic tape, 6 is a floppy disk, 7 is a printer, 8 is a magnetic disk, 11 is a binarization processing section, 12 is a degeneration processing section, 13 is a noise removal processing section, 14 15 is a line thinning processing unit, 15 is a vectorization processing unit, 16 is a crack width detection unit, and 17 is a vector length/
A width correction section 18 indicates a crack image data output section.

In FIG. 1, an imaging unit 1 is, for example, a television camera that takes images of cracks in concrete structures in place of the human eye. The input image control unit 2 inputs the image obtained by the imaging unit 1 into the data processing device 4 and performs CR processing.
It controls the imaging unit 1 and the CRT 3 for monitor for display on T3. The position movement for the first image is performed by a position movement device (not shown) according to the shape of the object to be investigated, and image position data information is input from the position movement device. One operator may be assigned to assist in the normal operation of the position moving device and the imaging section l. The data processing device 4 is composed of a personal computer or a dedicated professional sensor, and when image data is inputted from the imaging section 1 through the input image control section 4, the data processing device 4 calculates the position of the crack, the width of the crack, etc. from the image data. This is to extract crack information. The external storage devices that store both the crack information and image position data extracted by the data processing device 4 are the magnetic tape 5, the floppy disk 6, and the magnetic disk 8, and the printer 7 prints out the data. Although not shown, the crack information and image position data information may be transmitted to a large computer using a dedicated line or telephone line.

Next, crack measurement using the automatic crack measurement device shown in FIG. 1 will be explained. First, the image information of the subject is sent to the imaging unit l.
The input image control unit 2 captures the captured image as a digital image signal, the CRT 3 visually confirms the captured image, and the digital image signal is input to the data processing device 4 .

The data processing device 4 sets a darkness value for each pixel of the image data converted into a digital signal, binarizes the data, and then performs thinning to obtain a crack center line. Vectorization is then performed using line tracing to extract crack information such as the crack position and crack width. The data obtained through such image processing may be recorded in a storage device, or may be transmitted to a large computer using a dedicated line or telephone line.

Then, an overall image is constructed from the recorded or transmitted data, compared with design information, and crack analysis is performed.

Next, an example of image data processing by the data processing device 4 will be described with reference to FIGS. 2 and 3. In the data processing device, when image data as shown in FIG.
The image data digitized to the density of 255) is classified into two categories "1" (black) and rOJ (white) based on the darkness value.

Subsequently, the degeneration processing unit 12 degenerates each figure to a central point. In this process, for example, the center point (reduction point) is obtained by uniformly shrinking the figure from its boundary to the inside. Once the degeneracy point is determined, binary image data is again superimposed on this degeneracy point. and,
The noise removal processing unit 13 draws a circle with a constant radius centered on this degeneracy point, and if a figure falls within this circle, that figure is removed as noise.

The thinning processing unit 14 identifies removable points while maintaining the end point preservation conditions and the number of connections, and thins the line into a continuous point sequence of 8 connections at the final point. Although various methods for such thinning processing are already known, the present invention is not limited to the specific content of the thinning processing, and conventional methods may be selected and applied as appropriate. Of course, this is a good thing.

Thereafter, the vectorization processing unit 15 detects branch points and end points while line tracing ('fIA tracing) the center of the thinned crack, and determines the virtual vector end point where the virtual vector falls within n pixels from the trace line. By calculating and manipulating this, the center of the crack can be set to the starting point coordinates (Xl, Yl) and the ending point coordinates (X2, Yl).
2) is expressed as a vector group (broken line). As a result, directional information that can be understood by machines (computers) and humans can be obtained from crack images that do not have directional information as patterns. Note that by removing short vectors that do not have connection points, the needle noise can be further removed.

Once the vector data is obtained, the crack width detection section 16 finds the crack width W by comparing the vector data with the input image (raw data) shown in FIG. 3(a).

The width of this crack can be detected by taking the differentiation of the input image in the direction perpendicular to each vector and comparing that value with the darkness value.

The vector length/width correction unit 17 compares the vectors,
Correlation with the raw data is taken to correct the missing parts during the binarization stage, and the broken vectors are joined together. For example, the raw data values on the extension line of the vector in the middle of the cut vectors are tracked and the cut vectors are joined together.

The crack image data output unit 18 plots lines from vector data, converts it into an image of a crack as shown in FIG. 3 (bl), and outputs the image.

Fig. 4 is a diagram showing an example of output of analysis data of crack information, Fig. 4 fal is an output example of a crack image based on vector data, Fig. 4 (bl is a statistical processing of crack length with respect to crack width) An example of a graphical display, Figure 4 (
C1 is an output example of the statistical processing of the crack length against the angle between the arbitrary coordinate axes and the crack, and is graphed in Figure 4 (dl
is an output example of a graph obtained by statistically processing the crack length against the longitudinal position coordinate. Although it is appropriate to perform such statistical processing and display on a large-sized computer since it is necessary to input data of the structure to be investigated, it is also possible to display each image on an image data processing device.

Figure 5 is a diagram showing how the automatic crack measuring device according to the present invention is used when measuring cracks in underground cables, and Figure 6 is the automatic crack measuring device according to the present invention when measuring cracks in bridges. FIG. 3 is a diagram showing how the device is used. In the figure, 21 is an image input device (imaging unit);
Reference numeral 2 indicates a main unit, and the main unit 22 includes an input image control unit, a CRT 3 for a monitor, and a data processing device (
It incorporates a computer 4, a storage device such as a magnetic tape 5, a floppy disk 6, and a magnetic disk 8, and a printer 7, and is placed on a cart with wheels so that it can be easily moved.

The image input device 21 is extendably connected to the main device 22, captures an image of a wall surface, etc., and transmits image data to the main device 22. Therefore, while moving the cart, an image of the wall surface of a desired concrete structure can be captured by the image input device 21, and the image data is sent to the main device 22 where it is processed as described above and crack information is extracted.

Note that the present invention can be modified in various ways and is not limited to the above embodiments. For example, in the above example,
Although a TV camera was used for the imaging unit, COD (Cha
Other imaging means may also be used.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, an image of a part to be investigated is obtained using an image input device, and the image data processing device performs predetermined processing on this image to obtain necessary crack information. Since it is extracted, it is possible to always ensure a constant measurement accuracy of crack distribution and width, and there are no differences among surveyors.

In addition, only one operator is required, and the investigation labor and investigation period can be shortened. In addition, although a positioning device is required depending on the object of investigation, materials such as scaffolding are no longer required, and the dangers of working at heights can be avoided. Furthermore, general recording media such as magnetic tape can be used for data storage, and the required storage capacity can be secured in a unified format.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of one embodiment of the automatic crack measuring device of the present invention, FIG. 2 is a diagram showing a specific functional configuration example of the 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 how the automatic crack measuring device according to the present invention is used when measuring cracks in underground cables. FIG. 6 is a diagram showing how the automatic crack measuring device according to the present invention is used when measuring cracks in a bridge. l...imaging section, 2...input image control section, 3...C
RT, 4... data processing device (computer), 5.
...magnetic tape, 6...floppy disk, 7...
- Printer, 8... Magnetic disk, 11... Binarization processing section, 12... Degeneration processing section, 13... Noise removal processing section, 14... Thinning processing section, 15... Vectorization processing section, 16... Crack width detection section, 17... Vector length/width correction section, 18... Crack image data output section. Applicant: Tokyo Electric Power Company, Inc. (1 other person) agent
Patent attorney Ryukichi Abe (4 others) Figure 2 (α) (b)

Claims (5)

[Claims] (1) An automatic crack measurement device that measures cracks by processing image data obtained by imaging a structure, and includes a binarization means that binarizes the image data by setting a threshold. a degeneracy processing means that degenerates each figure of the obtained data toward the center point; a noise removal means that determines and removes noise by superimposing the figure on the center point obtained by the degeneracy processing means; The present invention further comprises: a thinning processing means for determining a center line of a group of connected pixels of connected data, a vectorization means for vectorizing the center line, and a crack detection means for detecting crack information from the vectorized center line and image data. An automatic crack measuring device featuring: (2) The automatic crack measuring device according to claim 1, wherein the noise removing means determines and removes noise based on whether or not the figure falls within a circle with a constant radius from the center point determined by the degeneracy processing means. . (3) The automatic crack measuring device according to claim 1, wherein the thinning processing means determines the center line of the connected pixel group and removes isolated points that are not linear. (4) The automatic crack measuring device according to claim 1, wherein the vectorization means vectorizes the center line and removes short vectors. (5) The automatic crack measuring device according to claim 1, wherein the crack detection means calculates the crack width by differentiating the image data with respect to a direction perpendicular to each vector.