KR20060018910A - Static movement measuring system for structure based on image processing for diagnosing and monitoring construction - Google Patents

Abstract

The present invention is a system for measuring biaxial coordinates and member length of a structure using a high resolution digital camera. The present invention is a method of measuring the shape change of the structure and the change in the length of the member using a simple digital camera in place of the conventional technology to measure the displacement and shape of the structure by a dial gauge, displacement sensor (LVDT) or surveying.

Static image displacement measurement system, target site, camera system, telephoto lens, image acquisition camera based on image processing

Description

Static Movement Measuring System for Structure Based on Image Processing for Diagnosing and Monitoring Construction}

1 is a configuration diagram of a camera system for static image displacement measurement

2 is developed in the present invention to calculate the displacement by processing the collected image

Computer systems with built-in programs

3 is a block diagram of a system for static image displacement measurement

4 is a reference coordinate input photo for static image displacement measurement

5 is a position input picture to calculate the shape of the structure and the length of the member

Figure 6 is a photograph of the result of calculating the shape of the structure and the length of the member

7 is a flowchart of execution of a static image measuring system;

■ Explanation of symbols for main parts of drawing ■

20: camera system 30: telephoto lens

40: image acquisition camera 50: computer

60: Pan / Tilt 70: Tripod

The present invention is a system for measuring biaxial coordinates and member length of a structure using a high resolution digital camera. The present invention is a method of measuring the shape change of the structure and the change in the length of the member using a simple digital camera in place of the conventional technology to measure the displacement and shape of the structure by a dial gauge, displacement sensor (LVDT) or surveying.

In general, facilities such as bridges, dams and chartered and embankment slopes have a significant social and economic impact when deformed or collapsed, as well as deaths. Therefore, continuous and long term safety management of the structure is very important. In particular, bridges are subjected to irregular loads and shocks caused by vehicles traveling at high speeds, and in Korea, the daily crossovers are very large, and sudden stimuli such as cold waves and typhoons are given. As described above, the structure causes long-term deformation such as deflection and torsion by changing the mechanical properties of the materials forming the structure, as well as external shocks and stimuli. Therefore, structures with repeated moving loads such as bridges need to be managed by continuous monitoring of long-term deformation and short-term vibration, while facilities such as dams and slopes need to be managed by continuous monitoring of long-term deformation. .

Conventionally, in order to measure the deformation and position change of a long-term structure, it is necessary to always install a contact displacement meter or a laser sensor for measurement, or to perform a precise survey using a high-performance light wave measuring instrument by a professional technician. When the displacement meter is installed to measure the long-term displacement of the structure, the installation cost is expensive, and when the survey is carried out, there is a problem in that expensive expenses as well as errors caused by the technician performing the survey are incurred.

In addition, in the case of a large slope or a large soil slope, in order to measure the displacement of a slope, a contact displacement meter was installed or a local displacement measurement was performed using a ground displacement gauge. A method for measuring displacement using a GPS system has been studied.

Therefore, in the present invention, the measurement system using the conventional contact sensor invented the static displacement measurement system of the structure using the image processing technology to solve the disadvantages of expensive installation cost and expense.

The technical problem to be achieved by the present invention is to form a reference coordinate system of the structure based on the image collected using a digital camera and to calculate the coordinate value of each point formed by the member based on this and to connect each point By estimating the length of the member, the displacement change and the shape change of the structure over time can be estimated.

In order to achieve the objective of static measurement that periodically measures the long-term displacement of the structure, even if it is not a technical expert, the present invention provides a camera system that collects aspects of the structure as an object and software for processing the collected images. It consists of a built-in computer system.

The static image displacement measurement system is composed of a camera system 20 for collecting images and a computer system 50 for measuring coordinates and lengths of respective positions using the collected images.

In FIG. 1, the camera system 20 includes a digital camera 40, a USB Connect 41 capable of transferring a profile from the camera 40 to a computer 50, and a telephoto lens 30 having sufficient performance to observe a long-range object. Pan / Tilt (60) which can be adjusted to finely rotate the camera 40 up, down, left and right so that the measurement target 10 is positioned within the image of the camera 40. , The pan / tilt 60 is composed of a tripod 70 that can be fixed so as not to move.

In FIG. 2, the computer system 50 is composed of a computer in which a program developed in the present invention is embedded so as to calculate the displacement by processing the collected image.

FIG. 4 shows a system installed for measuring displacement using a static image displacement measurement system according to the present invention. After the tripod 70 is installed in a stable place, the pan / tilt 60 is sufficiently fixed to the tripod 70 by using a fixing screw. The CCD camera 40 and the telephoto lens 30 are coupled to each other and then fixed to the pan / tilt 60 using fixing screws. The computer system 50 is installed adjacent to the camera system 20, and the CCD camera 40 is installed using the USB Connect 41 to transfer the image data collected by the CCD camera 40 to the computer system 50. And computer system 50 are connected.

Next, static measurement involves the following process.

Figure 4 shows the distance between the four points that can be compared and contrasted to designate the reference coordinates by transmitting the computer developed by the present invention to calculate the displacement after taking the bridge to be measured with a digital camera When a direct input is made using the drawings, the process of automatically calculating both the distortion and the actual dimension of the image based on these four values is shown as a photograph.

In FIG. 5, when the reference point is input, when the user drags the mouse pointer to a desired position, the actual dimension is continuously shown, and thus the distance and the position of the image can be easily known.

6 is a picture that can measure the designated markers in the actual bridge.

Next, the process of measuring the coordinates and the length of the structure through the image processing technology with the static image displacement measurement system will be described with reference to FIG.

S301 is an initialization step of the image acquisition camera converting the first digital signal.

S302 is a step of obtaining an image from an image acquisition camera.

S303 is a step of converting the image obtained in color to black and white.

Since the present invention is a system for measuring the movement of an object, color values are not necessary. Therefore, we use (Equation 1) to convert to grayscale as a process of reducing data for speeding up the process.

(식1)

(Eq. 1)

Here, R, G, and B are referred to as color image values composed of red, green, and blue, or RGB24 images.

I: Consisting of the image contrast, it is called gray image or Y8 image.

(s304) obtains a definite outline of the target through the thresholding process of the obtained monochromatic binary image. The demarcation process must consider the element of execution that contains the function T in (2).

(식2)

(Eq. 2)

는 점

의 명암을 나타내고,

는 점들의 궤적을 표시한다. 또한, 경계화(Threshoding)된 영상

는 (식3)으로 정의된다.At this time,

Point

Indicates the contrast of

Indicates the trajectory of the points. In addition, the thresholded image

Is defined by (3).

(식3)

(Eq. 3)

5 shows the actual captured image and the result of the boundary operation when the function T is 92.

(s305) finds a point to watch in the bordered image. In this case, draw a rectangular box indicating that the target is recognized on the circular target by selecting the minimum pixel in coordinates in FIG. Obtain and find the required viewpoint.

In s (305), since the center coordinates of the target obtained above are coordinates on a computer monitor, not actual coordinates, center calculation is performed to convert the actual coordinates into actual coordinates in order to measure the actual movement amount. Center calculation is described in detail below. First, Equation 4 is used to convert the image coordinates of the distorted image acquisition camera.

(식4)

(Eq. 4)

를 변형되지 않은 절대좌표

로 변환한다. 실제 좌표인

와

를 (식5)를 이용하여 구한다.Transformed coordinates

Unmodified world coordinates

Convert to The actual coordinates

Wow

Is obtained using (Eq. 5).

(Eq. 5)

In (s306), the position is obtained from the coordinate axis.

The final result is shown in FIG.

Most existing measurement systems only saw the bridge's up and down movement. This is because expensive sensors must be added by installing contact displacement meters in two axes, and installation is difficult. However, the dynamic image displacement measurement system can measure the biaxial displacement of the structure at once. It is also an advantage to be able to measure at a desired time from a distance with a simple target installation.

As described in detail above, the measurement by the static displacement measurement system of the structure according to the present invention has the feature that it is possible to measure the shape of the structure with a minimum image taken by a high-resolution camera, so that economic measurement is possible. It is easy to use.

Claims (3)

Telephoto lens 30 with sufficient performance to collect clear images, An image acquisition high resolution camera 40 which receives an image acquired through the telephoto lens and converts the input image information into a digital image, and inputs a reference coordinate system to the collected image, and then coordinate values of desired points based on the image. A static image displacement measurement system of a structure based on image processing for structure monitoring and diagnosis, which can measure the shape of the structure and change the length of members by calculating the distance between each point and each point. The method of claim 1; Since images captured by digital cameras are coordinates on a computer monitor, not actual coordinates, the structure monitoring and diagnosis is performed by inputting the reference coordinate system to convert the coordinate system on the monitor into the actual coordinate system to obtain the actual coordinate system of the structure. Static Image Displacement Measurement System of Structures Based on Image Processing. Initializing the image acquisition camera; Obtaining an image from the image acquisition camera; A system for static image displacement measurement based on image processing for monitoring and diagnosing a structure, comprising: converting transformed coordinates from absolute coordinates into unmodified absolute coordinates.

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