KR20200089467A - Algorithm and tool development for deformation detection of structures through profile - Google Patents

Abstract

The present invention relates to a method for developing an algorithm and a tool for detecting structure deformation through profile analysis of three-dimensional (3D) point cloud data to semi-automatically analyze deformation of a structure based on a profile. According to the present invention, the method comprises the following steps of: receiving 3D point cloud data of a deformed area; selecting top coordinates and bottom coordinates having a height difference in a profile from the 3D point cloud data of the deformed area; using the top coordinates and the bottom coordinates to calculate a directional vector of the profile; generating a unit normal vector perpendicular to a segment connecting the top coordinates and the bottom coordinates of the profile; using the unit normal vector to calculate a plane equation forming the profile; selecting the length of the unit normal vector perpendicular to the directional vector of the profile; calculating the size of a normal vector direction by product of the unit normal vector and the length; using the top coordinates, the bottom coordinates, and a range of the normal vector direction to generate a 3D profile analysis area; performing projection or rotation conversion to match a basic axis of the 3D profile analysis area with an axis in a 3D space wherein the profile is expressed; and displaying the 3D profile analysis area converted to match the basic axis of the 3D profile analysis area with the axis in the 3D space.

Description

Development of structure deformation detection algorithm and tool through cross-section analysis of 3D point cloud data{ALGORITHM AND TOOL DEVELOPMENT FOR DEFORMATION DETECTION OF STRUCTURES THROUGH PROFILE}

The following embodiments are used to develop cross-section-based algorithms and element technologies and tools including overall work procedures to effectively detect and analyze deformations of structures such as retaining walls and embankments from 3D point cloud data obtained by image registration or LIDAR surveying. It is about.

Dimensional point cloud data can be obtained through LIDAR (Light Detection and Ranging) survey or aerial image matching, and 3D point cloud data can be acquired through the development of optical sensors, image matching technology and LIDAR survey technology. Research has been continued to detect changes in structures or facilities by using them.

Recently, with the explosive growth of the unmanned aerial vehicle (UAV) or drone market, aerial images photographed using UAV are used in various fields. UAV video and UAV video are more widely used because they have a great advantage over conventional aviation video in terms of low cost, speed, and high resolution. Research to utilize point cloud data generated by UAV images in the field of disaster prevention is in the spotlight.

The technology for generating 3D point cloud data through LIDAR surveying or image matching can be considered established through research and technology development, and there are various commercial programs for this. However, there is no established method or software for detecting the deformation of a structure in 3D point cloud data, and since the operator sees and observes the shape of the data on the 3D point cloud data, the result depends on the skill of the operator. There is a problem that changes.

Accordingly, the present invention has an object to develop a tool and a semi-automatic algorithm based on a cross-section analysis that can detect deformation of a structure in 3D point cloud data.

The present invention was derived to improve the problem of the existing structure deformation information detection method in which the operator sees and observes the data type on the 3D point cloud data, and receives the cross-section direction and the reference plane as inputs to cross-section the structure. The goal is to develop algorithms and tools for semi-automatic analysis.

In order to achieve the above object, a method for detecting deformation of a structure through a cross-sectional analysis of 3D point cloud data according to an embodiment of the present invention includes: receiving 3D point cloud data of a deformation region; Selecting an upper coordinate and a lower coordinate in which a height difference of a cross section occurs in the 3D point cloud data of the deformation region; Calculating a direction vector of a cross section using the upper coordinate and the lower coordinate; Generating a unit normal vector perpendicular to a line segment connecting the upper and lower coordinates of the cross section; Calculating a plane equation constituting the cross section using the unit normal vector; Selecting a length of the unit normal vector perpendicular to the direction vector of the cross section, and calculating a size of the normal vector direction by multiplying the unit normal vector and the length; Generating a 3D cross-section analysis area using the upper coordinates, the lower coordinates, and coordinates that set a range of normal vector directions; Performing projection transformation or rotation transformation such that the basic axis of the 3D section analysis region and the axis in 3D space in which the section is exposed are the same; And displaying the 3D cross-section analysis area transformed such that axes in 3D space are the same.

At this time, the structure deformation detection method through the cross-section analysis of the three-dimensional point cloud data, may further include the step of automatically measuring the damaged portion using the measurement function of the cross-section analysis.

At this time, the structure deformation detection method through the cross-section analysis of the three-dimensional point cloud data, through the graph view function of the cross-section analysis screen to convert the three-dimensional section analysis area converted to the same axis in the three-dimensional space into a two-dimensional graph It may further include the step of outputting.

At this time, the step of converting and outputting the graph in 2D may include dividing point group data corresponding to the 3D section analysis area converted to have the same axis in 3D space into a predetermined distance; Calculating a maximum height value, a minimum height value, and an average height value of each divided class; And displaying a graph of the maximum height value of each divided grade, a graph of the minimum height value of each divided grade, and a graph of the average height value of each divided grade.

The present invention is an algorithm and tool for detecting deformation of a structure through cross-section-based analysis using 3D point cloud data generated by LIDAR surveying or image registration, and when a user inputs information about the cross-section direction and the reference plane of the damaged area Based on this, the target area is shown based on the cross-section direction, and the point where the structure is most deformed is detected based on the reference plane. Therefore, the present invention is expected to greatly improve the current working method of visually observing deformations of structures on 3D point cloud data through the present invention.

1 is a view showing an example of a three-dimensional section display method screen of damage analysis information according to an embodiment of the present invention.
2 is a diagram illustrating an example of a method for displaying a 2D cross-section of damage analysis information according to an embodiment of the present invention.
3 is a view showing an example of setting the cross-section direction of the deformation area according to an embodiment of the present invention.
4 is a view showing an example of setting the normal length in the cross-section in accordance with an embodiment of the present invention.
5 is a diagram illustrating an example of generating a section analysis area according to an embodiment of the present invention.
6 is a view showing a transformation of a coordinate system when performing rotation transformation of a cross-section analysis area according to an embodiment of the present invention.
7 is a diagram illustrating an example in which a 3D cross-section analysis result screen according to an embodiment of the present invention is expressed in real color.
FIG. 8 is a diagram illustrating an example in which a screen of a 3D cross-section analysis according to an embodiment of the present invention is expressed as a living image according to height.
9 is a diagram illustrating an example of a result of measuring the swelling phenomenon of a 3D cross-section analysis according to an embodiment of the present invention.
10 is a view showing an example of the settlement amount measurement result of the three-dimensional cross-section analysis according to an embodiment of the present invention.
11 is a view showing an example of the length measurement result of the three-dimensional cross-section analysis according to an embodiment of the present invention.
12 is a view showing an example of the area measurement result of the three-dimensional cross-section analysis according to an embodiment of the present invention.
13 is a diagram illustrating an example of a 2D cross-sectional analysis result when the section division is 30 according to an embodiment of the present invention.
14 is a diagram illustrating an example of a 2D cross-sectional analysis result when section division is 10 according to an embodiment of the present invention.
15 is a diagram illustrating an example of a result of applying a 2D cross-section analysis bar graph according to an embodiment of the present invention.
16 is a diagram showing an example of a result of applying a 2D cross-section analysis curve graph according to an embodiment of the present invention.
17 is a diagram illustrating an example of a 2D cross-sectional analysis result when a maximum height is applied according to an embodiment of the present invention.
18 is a diagram illustrating an example of a 2D cross-sectional analysis result when a minimum height is applied according to an embodiment of the present invention.

Specific structural or functional descriptions of the embodiments according to the concept of the present invention disclosed in this specification are exemplified only for the purpose of explaining the embodiments according to the concept of the present invention, and the embodiments according to the concept of the present invention It can be implemented in various forms and is not limited to the embodiments described herein.

Embodiments according to the concept of the present invention can be applied to various changes and can have various forms, so the embodiments will be illustrated in the drawings and described in detail herein. However, this is not intended to limit the embodiments according to the concept of the present invention to specific disclosure forms, and includes modifications, equivalents, or substitutes included in the spirit and scope of the present invention.

Terms such as first or second may be used to describe various components, but the components should not be limited by the terms. The above terms are only for the purpose of distinguishing one component from other components, for example, without departing from the scope of rights according to the concept of the present invention, the first component may be referred to as the second component, Similarly, the second component may also be referred to as the first component.

When an element is said to be "connected" or "connected" to another component, it is understood that other components may be directly connected to or connected to the other component, but there may be other components in between. It should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that no other component exists in the middle. Expressions describing the relationship between the components, for example, "between" and "immediately between" or "directly adjacent to" should be interpreted similarly.

The terminology used herein is only used to describe specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, the terms "include" or "have" are intended to designate the presence of a feature, number, step, action, component, part, or combination thereof implemented, one or more other features or numbers, It should be understood that the presence or addition possibilities of steps, actions, components, parts or combinations thereof are not excluded in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person skilled in the art to which the present invention pertains. Terms such as those defined in a commonly used dictionary should be interpreted as having meanings consistent with meanings in the context of related technologies, and should not be interpreted as ideal or excessively formal meanings unless explicitly defined herein. Does not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these embodiments. The same reference numerals in each drawing denote the same members.

Hereinafter, a method for developing a structure deformation detection algorithm and tools through cross-sectional analysis of 3D point cloud data according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 18.

Screen Layout

The present invention shows a cross-section and performs analysis based on point cloud data resulting from LIDAR surveying or image registration. As shown in <Table 1> below, the method of expressing the cross section was developed to be shown on separate screens using 3D section analysis and 2D section analysis.

Method of expression Explanation main function 3D section analysis Visualize the point cloud data in three dimensions with respect to the cross-section of the point cloud data resulting from multi-image matching -3D point cloud data city
-Change color of point cloud data (by height, due diligence)
-Change the size of point cloud data
-Damage information measurement function (length, area)
-Screen operation (enlarge, reduce, move, rotate, etc.) Two-dimensional section analysis (graph) Visualize in two dimensions by graphing the point cloud data on the cross section of the point cloud data resulting from multi-image matching -Change the graph height value (max, min, average)
-Type change (straight line, curved line, bar type)
-Shape change (circle, square, rhombus, triangle)
-Transparency change (transparency of graph area)

The 3D section analysis consists of basic screen manipulation functions, color and size changes of point groups, and measurement functions. The main screen of the section analysis is three-dimensional, and the point group data and the section area included in the section analysis area are shown.

The 2D section analysis is expressed as a simplified graph of 3D point cloud data, and is composed of menus that can change the height value, type, shape, and transparency of the graph. The main screen of the section analysis was set to 2D, and the X axis was set to the distance and the Y axis was set to height.

Next, FIG. 1 and FIG. 2 are screens showing a cross section of a location where damage has occurred in a target area in a three-dimensional graph on a point cloud and a two-dimensional graph.

1 is a view showing an example of a three-dimensional section display method screen of damage analysis information according to an embodiment of the present invention.

2 is a diagram illustrating an example of a method for displaying a 2D cross-section of damage analysis information according to an embodiment of the present invention.

Deformation area section direction setting

와 하단좌표

를 선택한다. 선택한 상/하단의 좌표의 높이차

가 단면분석 영역의 높이가 되며, 두 좌표를 이용하여 단면의 방향벡터

를 계산한다. 단면의 방향벡터

는 점군데이터 회전변환의 회전축에 결정에 이용된다.Upper coordinate where the height difference of the cross section occurs in the 3D point cloud data of the deformed area

And bottom coordinates

Choose Height difference of the selected top/bottom coordinates

Is the height of the section analysis area, and the direction vector of the section using two coordinates.

To calculate. Section direction vector

Is used to determine the rotation axis of the point group data rotation transformation.

3 is a view showing an example of setting the cross-section direction of the deformation area according to an embodiment of the present invention.

For setting the cross section direction of the deformed area, refer to the following <Equation 1>.

[Equation 1]

Create section normal vectors

과 수직인 단위 법선벡터

를 생성한다. 또한 수직인 법선벡터를 이용하여 단면을 구성하는 평면방정식이 계산된다.A line segment that connects the upper and lower coordinates of the section

Unit normal vector perpendicular to

Produces In addition, the plane equation that composes the cross section is calculated using the vertical normal vector.

For the normal vector, we can refer to the following <Equation 2>.

[Equation 2]

Deformation area section normal length setting

와 수직인 단위 법선벡터

의 길이(d)를 선택한다. 단위 법선벡터와 길이(d)의 곱으로 법선벡터방향의 크기

를 계산한다. Section direction vector

Normal to the unit normal vector

Select the length (d) of. Size of normal vector direction by multiplying unit normal vector and length (d)

To calculate.

4 is a view showing an example of setting the normal length in the cross-section in accordance with an embodiment of the present invention.

The size of the normal vector direction can be referred to the following <Equation 3>.

[Equation 3]

Create section analysis area

를 이용하여 3차원 단면분석 영역을 생성한다. The coordinates that set the range of the top/bottom coordinates (A, B) and normal vector direction of the section area

Create a 3D section analysis area using.

5 is a diagram illustrating an example of generating a section analysis area according to an embodiment of the present invention.

5, the coordinates of the short-lived analysis area are as follows.

, 단면분석 우측 상단 좌표

, Cross-section analysis upper right coordinate

, 단면분석 좌측 상단 좌표

, Cross-section analysis top left coordinates

, 단면분석 우측 하단 좌표

, Cross-section analysis, bottom right coordinate

, 단면분석 좌측 하단 좌표

, Cross-section analysis bottom left coordinates

Rotational transformation of section analysis area

In order to display the 3D point cloud data included in the section analysis area as a section and perform functions such as screen manipulation and measurement, projection transformation is performed so that the basic axis of the generated section area and the axis in the 3D space where the section is displayed are the same. A rotation conversion process is required. When the coordinate system in space is rotated by a certain angle with respect to each axis, the new coordinate system generated through rotation transformation can be expressed as the product of the rotation matrix and the original coordinate system as follows.

6 is a view showing a transformation of a coordinate system when performing rotation transformation of a cross-section analysis area according to an embodiment of the present invention.

The correlation between the transformed coordinates can be expressed as <Equation 4>.

[Equation 4]

And if it is expressed as a matrix, it can be expressed as <Equation 5>.

[Equation 5]

By setting the cross-section direction of the generated cross-section area as the X-axis, the height as the Y-axis, and the center of the cross-section as the origin, the rotation amount is calculated based on the Z-axis representing the height of the data for 3D point cloud data included in the cross-section. Rotational transformation was applied.

The rotation amount based on the Z axis can be referred to the following <Equation 6>.

[Equation 6]

Sectional city

When rotation transformation is applied to the coordinates of the 3D point group and the section area through the rotation conversion process, the point group data and the section area are displayed on the section display screen, and the screen can be switched to the 2D graph through the [Graph view] function. . Next, FIGS. 7 and 8 are the results of changing the point cloud color of the damaged area data through 3D cross-sectional analysis.

7 is a diagram illustrating an example in which a 3D cross-section analysis result screen according to an embodiment of the present invention is expressed in real color.

FIG. 8 is a diagram illustrating an example in which a screen of a 3D cross-section analysis according to an embodiment of the present invention is expressed as a living image according to height.

Automatic measurement

Using the measurement function of the cross-section analysis, it is possible to automatically measure the swelling of the retaining wall or the amount of settlement on the slope.

When the user creates a virtual section (line segment) representing the reference plane in the section analysis screen of the retaining wall or slope, the plane equation of the reference plane is calculated by combining with the previously calculated section normal vector, and the vertical plane is damaged from the reference plane. Measure the point with the largest amount of change and the amount of change.

-Create a reference plane -> Search for the data farthest away from the reference plane -> Measure the amount of change

The distance can be calculated by referring to <Equation 7> below.

[Equation 7]

9 and 10 below are the results of measuring the fullness and deflection of the mock damage for the slope area, the fullness was measured to be 0.32m, and the deflection was 0.21m.

9 is a diagram illustrating an example of a result of measuring the swelling phenomenon of a 3D cross-section analysis according to an embodiment of the present invention.

10 is a view showing an example of the settlement amount measurement result of the three-dimensional cross-section analysis according to an embodiment of the present invention.

Manual measurement

The distance and area of the damaged area can be measured through the measurement function of 3D section analysis. For accurate measurement results, measurement coordinates measured by the user are projected on a two-dimensional plane.

-Coordinates in 3D -> Projection on 2D plane -> Measurement of length or area

In the distance measurement, the distance and total distance of each line segment are measured by generating a line segment for a 3D point group. Area measurement calculates the area by generating polygons for point clusters in the damaged area, and the measured information is listed in the measurement list. 11 and 12 below, as a result of measuring the length of the slope and the damage area for the slope area, the length of the slope was 2.75m and the area of the simulated damage was 0.23㎡.

11 is a view showing an example of the length measurement result of the three-dimensional cross-section analysis according to an embodiment of the present invention.

12 is a view showing an example of the area measurement result of the three-dimensional cross-section analysis according to an embodiment of the present invention.

2D graph city function

You can switch the screen to a 2D graph through the [Graph view] function of the section analysis screen. In order to show the point group data of the 3D section in a graph on the 2D, the point group data was divided into a certain distance, and the maximum, minimum, and average height values of each grade were calculated. 13 and 14 below are the results of a two-dimensional cross-sectional analysis graph showing by changing the number of section divisions.

13 is a diagram illustrating an example of a 2D cross-sectional analysis result when the section division is 30 according to an embodiment of the present invention.

14 is a diagram illustrating an example of a 2D cross-sectional analysis result when section division is 10 according to an embodiment of the present invention.

In the 2D cross-section analysis, the maximum, minimum, and average heights of point cloud data were calculated, and the data were plotted by color, and the height values of each section were displayed on a label. It was developed to change the number of divisions, select the maximum, minimum, and average data of the height values individually to display the graph, and to show the shape of the graph as a linear or curved line. In addition, the symbol representing the representative value of each grade can be changed into various shapes, and the transparency of the graph area can be adjusted.

15 and 16 below are result screens showing the shape of the graph in a bar shape and a curve shape.

15 is a diagram illustrating an example of a result of applying a 2D cross-section analysis bar graph according to an embodiment of the present invention.

16 is a diagram showing an example of a result of applying a 2D cross-section analysis curve graph according to an embodiment of the present invention.

17 and 18 below are the results of comparing and showing the data of the graph by applying the maximum/minimum height in the 2D cross-section analysis to confirm the cross-section of the damaged shape of the embankment slope area. As a result of applying the maximum/minimum height, it is possible to check the damage shape with a width of 1 m or more.

17 is a diagram illustrating an example of a 2D cross-sectional analysis result when a maximum height is applied according to an embodiment of the present invention.

18 is a diagram illustrating an example of a 2D cross-sectional analysis result when a minimum height is applied according to an embodiment of the present invention.

The invention described above may be implemented with hardware components, software components, and/or combinations of hardware components and software components. The devices and components described in the embodiments include, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor (micro signal processor), a microcomputer, a field programmable gate array (FPGA), and programmable logic (PLU). unit), a microprocessor, or any other device capable of executing and responding to instructions, may be implemented using one or more general purpose computers or special purpose computers. The processing device may run an operating system (OS) and one or more software applications running on the operating system. In addition, the processing device may access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of understanding, a processing device may be described as one being used, but a person having ordinary skill in the art, the processing device may include a plurality of processing elements and/or a plurality of types of processing elements. It can be seen that may include. For example, the processing device may include a plurality of processors or a processor and a controller. In addition, other processing configurations, such as parallel processors, are possible.

The software may include a computer program, code, instruction, or a combination of one or more of these, and configure the processing device to operate as desired, or process independently or collectively You can command the device. Software and/or data may be interpreted by a processing device or to provide instructions or data to a processing device, of any type of machine, component, physical device, virtual equipment, computer storage medium or device. , Or may be permanently or temporarily embodied in the transmitted signal wave. The software may be distributed on networked computer systems, and stored or executed in a distributed manner. Software and data may be stored in one or more computer-readable recording media.

The method according to the embodiment is implemented in the form of program instructions that can be executed through various computer means and can be recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, or the like alone or in combination. The program instructions recorded on the medium may be specially designed and configured for an embodiment or may be known and available to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs, DVDs, and magnetic media such as floptical disks. -Hardware devices specially configured to store and execute program instructions such as magneto-optical media, and ROM, RAM, flash memory, and the like. Examples of program instructions include high-level language code that can be executed by a computer using an interpreter, etc., as well as machine language codes produced by a compiler. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

As described above, although the embodiments have been described by a limited embodiment and drawings, those skilled in the art can make various modifications and variations from the above description. For example, the described techniques are performed in a different order than the described method, and/or the components of the described system, structure, device, circuit, etc. are combined or combined in a different form from the described method, or other components Alternatively, even if replaced or substituted by equivalents, appropriate results can be achieved.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (5)

Receiving 3D point cloud data of the deformed region;
Selecting an upper coordinate and a lower coordinate in which a height difference of a cross section occurs in the 3D point cloud data of the deformation region;
Calculating a direction vector of a cross section using the upper coordinate and the lower coordinate;
Generating a unit normal vector perpendicular to a line segment connecting the upper and lower coordinates of the cross section;
Calculating a plane equation constituting the cross section using the unit normal vector;
Selecting a length of the unit normal vector perpendicular to the direction vector of the cross section, and calculating a size of the normal vector direction by multiplying the unit normal vector and the length;
Generating a 3D cross-section analysis area using the upper coordinates, the lower coordinates, and coordinates that set a range of normal vector directions;
Performing projection transformation or rotation transformation such that the basic axis of the 3D section analysis region and the axis in 3D space in which the section is exposed are the same; And
Displaying the 3D section analysis area converted so that the axes in 3D space are the same.
Structural deformation detection method through cross-sectional analysis of 3D point cloud data including a.
According to claim 1,
Step to automatically measure the area where damage occurred using the measurement function of the section analysis
Structural deformation detection method through cross-sectional analysis of 3D point cloud data further comprising a.
According to claim 1,
Converting and outputting the 3D section analysis area converted to the same axis in the 3D space through the graph view function of the section analysis screen into a 2D graph.
Structural deformation detection method through cross-sectional analysis of 3D point cloud data further comprising a.
According to claim 3,
The step of converting and outputting the graph on the two-dimensional,
Dividing point group data corresponding to the 3D cross-section analysis area converted to have the same axis in the 3D space into a predetermined distance;
Calculating a maximum height value, a minimum height value, and an average height value of each divided class; And
Displaying a graph of the maximum height value of each divided grade, a graph of the minimum height value of each divided grade, and a graph of the average height value of each divided grade.
Structural deformation detection method through cross-sectional analysis of 3D point cloud data including a.
A computer-readable recording medium, characterized in that a program for executing the method of any one of claims 1 to 4 is recorded.

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