阅读说明：本技术 一种利用二维码和特征点匹配技术监测裂缝变化的方法 (Method for monitoring crack change by using two-dimensional code and characteristic point matching technology ) 是由 丁勇 王舒林 唐汉宸 于 2020-05-13 设计创作，主要内容包括：本发明涉及一种利用二维码和特征点匹配技术监测裂缝变化的方法,该方法利用相机拍摄裂缝墙体,可以实时监测到裂缝的变化做出准确及时的预警；该方法成本较低,只需要标识二维码和一个摄像头就可以实施裂缝的监测；相比较于人工方法的耗时耗力,该监测方法更省时方便；该方法可以监测墙体上复杂裂缝或多条裂缝的变化,相较于常规方法只能监测单条裂缝的变化；该方法的应用场景也很广泛,不仅适用于建筑裂缝的监测,也适用于大坝、边坡变形的监测。(The invention relates to a method for monitoring crack changes by utilizing a two-dimensional code and characteristic point matching technology, wherein a camera is utilized to shoot a crack wall body, so that the crack changes can be monitored in real time to make accurate and timely early warning; the method is low in cost, and the crack can be monitored only by identifying the two-dimensional code and one camera; compared with the time and labor consumption of a manual method, the monitoring method is more time-saving and convenient; the method can monitor the change of a complex crack or a plurality of cracks on the wall body, and compared with the conventional method, the method can only monitor the change of a single crack; the method has wide application scenes, is suitable for monitoring the cracks of the building, and is also suitable for monitoring the deformation of the dam and the side slope.)

1. A method for monitoring crack change by utilizing two-dimensional code and characteristic point matching technology is characterized in that: comprises that

Step 1: setting a camera: when the crack reaches the area with cracks on the building wall, opening the camera to enable the lens of the camera to be perpendicular to the crack wall surface and enable the camera picture to cover the cracks, and starting a reference line in the camera picture;

step 2: editing a reference line: the camera picture comprises four reference lines, wherein a longitudinal upper reference line is a No. 1 line, a longitudinal lower reference line is a No. 2 line, a transverse left reference line is a No. 3 line, a right reference line is a No. 4 line, and the four reference lines divide a shot wall into nine areas;

and step 3: pasting a two-dimensional code: pasting a two-dimensional code on a wall surface corresponding to the intersection point of the reference line, pasting a two-dimensional code 1 on the intersection point of the No. 1 line and the No. 4 line, and pasting a two-dimensional code 2 on the intersection point of the No. 2 line and the No. 3 line;

and 4, step 4: taking a picture: shoot t respectively₀、t_nPhotos of the crack wall at two moments;

and 5: calibration photograph: calibrating the two pictures to be at the same shooting angle;

step 6: image processing: performing difference on the two pictures to obtain the length and width change of the crack area;

and 7: analyzing the crack change region by using a K-means clustering algorithm to obtain t_nTime of day comparison t₀The portion of the crack length that changes at that time;

and 8: calculating the length: and calculating the proportional relation between the two-dimension code and the actual two-dimension code in the image, acquiring the coordinates of two points of the newly increased crack length part, calculating the newly increased crack length in the image, and combining the proportional relation to obtain the newly increased actual crack length.

2. The method for monitoring crack changes by using two-dimensional code and feature point matching technology according to claim 1, wherein the method comprises the following steps: the center of the two-dimensional code coincides with the intersection point of the reference line.

3. The method for monitoring crack changes by using two-dimensional code and feature point matching technology according to claim 1, wherein the method comprises the following steps: the angular points of the three position detection areas of the two-dimensional code form an isosceles right triangle, and the vertex of the isosceles right triangle is vertically upward.

4. The method for monitoring crack changes by using two-dimensional code and feature point matching technology according to claim 1, wherein the method comprises the following steps: in the step 5, the two photos at different moments are registered by using the characteristic points of the two-dimensional code; the characteristic points are black and white pixel blocks which are obviously different from surrounding pixel points in the two-dimensional code.

Technical Field

The invention relates to a method for monitoring crack change by using a two-dimensional code and characteristic point matching technology, and belongs to the technical field of image recognition.

Background

After cracks appear on the building, the development conditions of the cracks can be known, so that a safety assessment can be made on the whole building, safety accidents can be avoided, and unnecessary economic loss is reduced. The method comprises the steps of pasting a two-dimensional code on a building wall body with cracks, shooting pictures of the crack wall body at different moments by using a camera, analyzing crack change conditions of the pictures of the crack wall body at different moments, and making safety assessment on the building according to the crack change conditions. Therefore, a method for monitoring crack changes by using two-dimensional codes and a feature point matching technology is needed.

Disclosure of Invention

In order to solve the technical problem, the invention provides a method for monitoring crack change by using two-dimension code and characteristic point matching technology, which comprises the following steps

Step 1: setting a camera: when the crack area on the building wall is reached, opening a camera to enable a lens of the camera to be perpendicular to the crack wall surface and enable a picture of the camera to cover the crack on the wall surface, and setting an opening reference line in the camera;

step 2: editing a reference line: the method comprises the steps that a camera picture comprises four reference lines, the number of the four reference lines is determined, the longitudinal upper reference line is the No. 1 line, the longitudinal lower reference line is the No. 2 line, the transverse left reference line is the No. 3 line, the right reference line is the No. 4 line, and the four reference lines divide a shot wall into nine areas;

and step 3: pasting a two-dimensional code: pasting a two-dimensional code on the wall surface corresponding to the intersection point of the reference line, pasting a two-dimensional code 1 on the intersection point of the No. 1 line and the No. 4 line, and pasting a two-dimensional code 2 on the intersection point of the No. 2 line and the No. 3 line;

and 4, step 4: taking a picture: respectively shooting the pictures of the crack wall at different times;

and 5: calibration photograph: calibrating the two pictures to be at the same shooting angle;

step 6: image processing: and performing subtraction on the two pictures to obtain detection of one change of the crack area.

And 7: analyzing the crack change region by using a K-means clustering algorithm to obtain a part of the change of the crack length at the time tn compared with the time t 0;

and 8: calculating the length: and calculating the proportional relation between the two-dimension code and the actual two-dimension code in the image, acquiring the coordinates of two points of the newly increased crack length part, calculating the newly increased crack length in the image, and solving the newly increased actual crack length by combining the proportional relation.

Furthermore, the center of the two-dimensional code coincides with the intersection point of the reference line. The superposition is to paste the two-dimensional code identification for the standard and prepare for the registration of the following pictures.

Further, in the step 5, the two photos at different times are registered by using the feature points of the two-dimensional code; the characteristic points are black and white pixel blocks which are obviously different from surrounding pixel points in the two-dimensional code.

The invention has the beneficial effects that:

the present invention provides a new method for monitoring fracture changes, which can monitor the width and length changes of the fracture. The novel method for monitoring the cracks has the following advantages: according to the method, the crack wall is shot by using the camera, so that the change of the crack can be monitored in real time to make accurate and timely early warning; the method is low in cost, and the crack can be monitored only by identifying the two-dimensional code and one camera; compared with the time and labor consumption of a manual method, the monitoring method is more time-saving and convenient; the method can monitor the change of a complex crack or a plurality of cracks on the wall body, and compared with the conventional method, the method can only monitor the change of a single crack; the method has wide application scenes, is suitable for monitoring the cracks of the building, and is also suitable for monitoring the deformation of the dam and the side slope.

Drawings

Figure 1 is a schematic view of the structure of the present invention,

figure 2 is a schematic diagram of the structure of four reference lines in the camera view of the present invention,

figure 3 is a schematic diagram of the position structure of the two-dimensional code of the present invention,

figure 4 is a photograph of a crack taken at various times in accordance with the present invention,

figure 5 is a schematic view of the registration of two photographs of the invention,

FIG. 6 is an analysis structure diagram of the present invention using the K-means clustering algorithm.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic views illustrating only the basic structure of the present invention in a schematic manner, and thus show only the constitution related to the present invention.

The method for monitoring the crack change by utilizing the two-dimension code and characteristic point matching technology comprises the following specific operation steps:

the method comprises the following steps: finding the crack area on the building wall, opening the camera, making the lens of the camera perpendicular to the crack wall and covering all crack information on the wall as much as possible with the camera picture, as shown in fig. 1. And an opening reference line is set in the camera.

Step two: reference line numbers in the camera are determined, a longitudinal upper reference line is a line No. 1, a longitudinal lower reference line is a line No. 2, a transverse left reference line is a line No. 3, a right reference line is a line No. 4, and four reference lines equally divide a shot wall into nine areas as shown in FIG. 2.

Step three: paste the two-dimensional code on the wall that the nodical corresponds, paste two-dimensional code 1 in the nodical department of No. 1 line and No. 4 lines, paste two-dimensional code 2 in the nodical department of No. 2 lines and No. 3 lines, the center of two-dimensional code coincides with the nodical of reference line. The angular points of the three position detection areas of the two-dimensional code form an isosceles right triangle, and the vertex of the isosceles right triangle is vertically upward. When shooting with a camera, there are two shooting modes, namely horizontal shooting and vertical shooting, and the direction of the vertex of the two-dimensional code indicates that the camera is the shooting mode of vertical shooting, as shown in fig. 3.

Step four: shoot t respectively₀、t_nThe photos of the crack wall at different moments are shot according to the pointing direction of the vertex of the two-dimensional code, as shown in fig. 3.

Step five: in consideration of the influences of subjective factors and external factors such as shooting angles and the like when the photos are shot, the crack photos shot at different moments are not shot at the same angle, so that the two photos at different moments are registered by using the characteristic points of the two-dimensional code, and the two photos are calibrated to be at the same shooting angle. The characteristic points are points with obvious difference with surrounding pixel points in the image, and the two-dimensional code is reflected in the image and consists of different black and white pixel blocks, so that the registration is performed by utilizing the characteristic points of the two-dimensional code, the registration is faster and more accurate, and the image is a registration schematic diagram of two photos at different moments.

Step six: and performing difference on the two pictures to obtain detection of one change of the crack area.

Step seven: analyzing the crack change region by using a K-means clustering algorithm, wherein the broken line part of the crack is t as shown in the figure_nTime of day comparison t₀At that moment, the portion of the crack length changes.

The two-dimensional code is simultaneously used as a scale for measuring the length change of the crack, the actual size of the two-dimensional code is known, the size of the two-dimensional code in an image can be measured by using an image processing technology, and the newly added length of the crack can be obtained only by acquiring the coordinates of two points of the newly added length part of the crack by using the proportional relation between the image size and the actual size.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The meaning of "and/or" as used herein is intended to include both the individual components or both.

The term "connected" as used herein may mean either a direct connection between components or an indirect connection between components via other components.

In light of the foregoing description of the preferred embodiment of the present invention, many modifications and variations will be apparent to those skilled in the art without departing from the spirit and scope of the invention. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.