CN102183524B - Double-CCD (Charge Coupled Device) detecting method and system for apparent defect assessment of civil engineering structure - Google Patents

Abstract

The invention provides a double-CCD (Charge Coupled Device) detecting method and equipment for apparent defect assessment of a civil engineering structure. The method comprises the following methods: a structure configuration method of the apparent defect double-CCD detecting system, a space coordinate calculating method of characteristic points of the double-CCD detecting method, a matching method of the image characteristic points of the structure apparent defect and an assessing method of the size of the structure apparent defect. The detecting system is composed of a double-CCD camera, a bracket, a double-path image collecting card, a computer and apparent defect detection assessing software, wherein the double-CCD camera is installed on the bracket and the double-CCD camera is connected to the double-path image collecting card through a lead wire; the double-path image collecting card is installed on the computer and the assessing software is used for controlling the system to realize collection, processing and assessment of the structure apparent defect images. In the invention, the system has the functions of carrying out synchronous collection by double-CCD, displaying and storing images, matching characteristics, assessing defects and damages and providing a detection report. The system provided by the invention also has the advantages of real-time property of collection and rapidness in processing so that the system is suitable for the field measurement of the civil engineering structures.

Description

The two CCD detection methods and the system that are used for the evaluation of civil engineering structure visual defects

Technical field

What the present invention relates to is a kind of civil engineering structure defect detecting technique field, specifically a kind of two CCD detection methods and system for the evaluation of civil engineering structure visual defects.

Background technology

Because the variation of external environment condition and the influence of human error, civil engineering structure various damages in various degree can occur in the process under arms, and the defective of xoncrete structure originates from or is revealed in body structure surface mostly, as crack, hole, etch pit, groove etc., but integrally-built security, integrality and causativity are reduced, influence the normal use of structure.The existence of these defectives is seriously threatening the safe reliability of structure, may cause structural instability or strength failure, and is serious even influence the normal operation of engineering and the performance of benefit.In order to guarantee safety in production, therefore must regularly detect and safety assessment structure.

The traditional detection method of civil engineering structure visual defects is mainly by range estimation, carried out visual inspection or felt by the testing staff.The range of size in crack can only be probably estimated in range estimation like this, and can not obtain accurate result; And, because the restriction of self-condition makes visual method have shortcomings such as detectability is limited, detecting reliability is low, detection time is long, expense height.In order to improve detection efficiency and precision, reduce labour intensity, save testing cost, people are exploring more effective detection means and method always.

CCD detects imaging technique as a kind of important nondestructiving detecting means, have that speed is fast, noncontact, degree of precision, simple operation and other advantages, bring into play huge effect in a lot of fields, will provide a kind of new technical support for the detection of structure visual defects in field of civil engineering.And adopt two CCD detection methods not only can evaluate the face inside dimension of civil engineering structure visual defects, also can realize flaw size from the face depth survey, can satisfy the actual demand of engineering detecting better.

Summary of the invention

The object of the present invention is to provide a kind of two CCD detection methods and system thereof that is applicable to the evaluation of civil engineering structure visual defects.

A kind of two CCD detection methods for the evaluation of civil engineering structure visual defects are as follows:

(1) structure configuration method of the two CCD detection systems of visual defects:

In order to obtain the volume coordinate of the apparent defect characteristic point of structure from two dimensional image, two CCD cameras need to obtain two width of cloth images that comprise the apparent defect characteristic point of structure from diverse location; With two CCD cameras intersect from different perspectives put observation same testee, the structure configuration of two CCD detection systems at first will be determined the visual angle of single CCD camera, actual conditions of using at engineering then, design parallax range B and angle α between two CCD cameras, to obtain best public view field, for obtaining the visual angle of CCD camera in the actual detected, need make the CCD camera vertical with a plane, adjust the distance of CCD camera and body structure surface, make clear picture, and allow the optical axis of CCD camera point to cross center on the plane, and allow the optical axis of CCD camera point to cross center on the plane, on the orthogonal direction in cross center, place two scales, take pictures then, according in the image the distance of the scale that can photograph, can calculate the CCD camera in the horizontal direction with vertical direction on the visual angle, at last according to the parallax range of two CCD cameras, the angle of video camera and baseline and the visual angle of video camera just can calculate the public view field of two CCD detection systems;

(2) the unique point spatial coordinates calculation method of two CCD detection methods:

Two CCD cameras are watched body structure surface unique point P at synchronization, use left and right sides CCD camera to obtain the image that P is ordered respectively, and their image coordinate is respectively P _l=(X _l, Y _l), P _r=(X _r, Y _r), when two CCD image of camera planes on same plane, then the Y coordinate of the image coordinate of unique point P is identical, i.e. Y _Left=Y _Right=Y is obtained by the perspective transform principle:

$X_{\mathrm{left}}=f\frac{x_c}{z_c}$ $X_{\mathrm{right}}=f\frac{(x_c-B)}{z_c}$ $Y=f\frac{y_c}{z_c}$

Then the time difference is: Disparity=|X _Left-X _Right|=X _Left-X _Right

Can calculate the volume coordinate of structured surface features point under two CCD detection system coordinate systems thus is:

$\left\{\begin{array}{c}{x}_c=\frac{B\·X_l}{\mathrm{Disparity}}\\ y_c=\frac{B\·Y}{\mathrm{Disparity}}\\ z_c=\frac{B\·f}{\mathrm{Disparity}}\end{array}\right.$

As long as the match point that a bit can find correspondence arbitrarily in right CCD camera image planes therefore on the left CCD phase machine side, be that the two is the point of space same point on the CCD camera of the left and right sides, just can determine the volume coordinate of the apparent defect characteristic point of structure according to the intrinsic geometrical constraint of two CCD cameras, this kind method is point-to-point computing, as long as have a few on the image and have match point, just can participate in above-mentioned computing, thereby obtain the apparent defect characteristic point of structure volume coordinate, thereby it is higher to measure efficient.

(3) matching process of the apparent defect image unique point of structure:

The coupling of visual defects image characteristic point is the method by images match, seek out in two width of cloth images mutual corresponding relation between the unique point, thereby determine the same unique point coordinate in two width of cloth images respectively, the characteristic matching of defect image need be carried out feature extraction to two width of cloth visual defects images, can adopt Harris angle point extraction algorithm, SUSAN angle point extraction algorithm or SIFT feature point extraction algorithm;

Obtaining the coordinate time of image, can adopt two kinds of methods of interactive identification and automated characterization coupling, the advantage of interactive identification is to find same unique point exactly in two views, shortcoming is the coordinate that can not determine accurately a little, the automated characterization coupling is to utilize the extraction of unique point and matching algorithm that unique point is accurately located, but the matching result of unique point not necessarily can match the key position of defective, therefore can carry out the coupling of unique point earlier by automatic matching method, can not reach requirement as matching result, the method that re-uses interactive identification is mated

In two CCD detection methods, the coupling of character pair point mainly is the similarity degree of geometric primitive such as two width of cloth image mid points, edge or zone, projected to the image coordinate of the corresponding point that form in two width of cloth images again by same unique point respectively, just can go out the volume coordinate of unique point according to the calculated with mathematical model of two CCD detection methods;

(4) assessment method of the apparent flaw size of structure:

After the volume coordinate that gets access to the apparent defect characteristic point of structure, the length of defective just can be tried to achieve by 2 distance in the space, and the coordinate of establishing in the space at 2 is respectively P ₁(X ₁, Y ₁, Z ₁), P ₂(X ₂, Y ₂, Z ₂), then the length computation formula is:

$L=\sqrt{{(X_1-X_2)}^2+{(Y_1-Y_2)}^2+{(Z_1-Z_2)}^2}$

The depth survey of defective at first needs to set up a measuring basis face, the degree of depth of being asked is with respect to this reference field, this reference field is the space, can utilize the unique point in the three dimensions, try to achieve this space plane according to the computing formula of space plane, the coordinate of establishing three points in the space is respectively P ₁(X ₁, Y ₁, Z ₁), P ₂(X ₂, Y ₂, Z ₂), P ₃(X ₃, Y ₃, Z ₃), then the space plane equation is:

[(Y ₁Z ₂+Y ₂Z ₃+Y ₃Z ₁)-(Y ₃Z ₂+Y ₂Z ₁+Y ₁Z ₃)]X

+[(X ₁Z ₂+X ₂Z ₃+X ₃Z ₁)-(X ₂Z ₂+X ₂Z.+X ₁Z ₃)]Y

+[(X ₁Y ₂+X ₂Y ₃+X ₃Y ₁)-(X ₃Y ₁+X ₂Y ₁+X ₃Y3)]Z

+[(X ₁Y ₂Z ₃+X ₂Y ₃Z ₁+X ₃Y ₁Z ₃)-(X ₃Y ₂Z ₁+X ₂Y ₁Z ₃+X ₁Y ₃Z ₂)]＝0

(Y ₁Z ₂+Y ₂Z ₃+Y ₃Z ₁)-(Y ₃Z ₂+Y ₂Z ₁+Y ₁Z ₃)＝A

(X ₁Z ₂+X ₂Z ₃+X ₃Z ₁)-(X ₂Z ₂+X ₂Z.+X ₁Z ₃)＝B

Order

(X ₁Y ₂+X ₂Y ₃+X ₃Y ₁)-(X ₃Y ₁+X ₂Y ₁+X ₃Y ₃)＝C

(X ₁Y ₂Z ₃+X ₂Y ₃Z ₁+X ₃Y ₁Z ₃)-(X ₃Y ₂Z ₁+X ₂Y ₁Z ₃+X ₁Y ₃Z ₂)＝D

Then plane equation is AX+BY+CZ+D=0,

If coordinates of spatial points is K (X _k, Y _k, Z _k), then spatial point to the distance of space plane is:

$d=\frac{|\mathrm{Aa}+\mathrm{Bb}+\mathrm{Cc}-D|}{\sqrt{A^2+B^2+C^2}}$

Calculate length, width and the depth information of structure visual defects thus,

As long as therefore obtained the coordinate of spatial point in image, just can calculate the three-dimensional coordinate of spatial point, and then try to achieve the relative position relation of spatial point, also just finished the assessment of impairments of civil engineering structure visual defects.

The present invention also has following feature:

A kind of two CCD detection systems for the evaluation of civil engineering structure visual defects, system detects evaluation software by two CCD cameras, support, two-way image pick-up card, computing machine and visual defects and forms, it is characterized in that: two CCD cameras are rack-mount, two CCD cameras are wired on the two-way image pick-up card, the two-way image pick-up card is installed on computers, is detected the acquisition process evaluation of evaluation software control detection system implementation structure visual defects image by visual defects; Described pair of CCD camera model performance is identical, have than the control of high image resolution and automatic gain and bias light automatic compensation function, and optical lens size and ccd sensor size must mate, and interface type mates, and is mega pixel level camera lens; Described support can be installed two CCD cameras, and its symmetria bilateralis and can drawing close to the center simultaneously can realize level and the pitch rotation of each camera; Described two-way image pick-up card can be analog acquisition card or digital collection card, and interface type can be IEEE1394, PCI-Express or USB2.0; Described visual defects detects evaluation software is realized two-way picture synchronization collection, demonstration processing, characteristic matching, assessment of impairments and interactive identification by computer control function, according to the visual defects three-dimensional dimension of visual defects evaluation algorithm measurement structure, and provide structure apparent defects detection report.

The present invention has that two CCD gather synchronously, image shows storage, characteristic matching, defect damage evaluation and function that examining report is provided, and has real-time collection, fast processing, simple operation and other advantages, is suitable for the engineering structure in-site measurement.

Description of drawings

Fig. 1 is the structure configuration mode figure of two CCD camera detection.

Fig. 2 is spatial coordinates calculation schematic diagram of the present invention.

Fig. 3 is detection schematic diagram of the present invention.

Embodiment

Embodiment:

A kind of two CCD detection methods for the evaluation of civil engineering structure visual defects are as follows:

(1) structure configuration method of the two CCD detection systems of visual defects:

In order to obtain the volume coordinate of the apparent defect characteristic point of structure from two dimensional image, two CCD cameras need to obtain two width of cloth images that comprise the apparent defect characteristic point of structure from diverse location; Two CCD cameras are intersected from different perspectives put the same testee of observation, Fig. 1 be the structure configuration mode of pair CCD camera detection.

The structure configuration of two CCD detection systems at first will be determined the visual angle of single CCD camera, actual conditions of using at engineering then, design parallax range B and angle α between two CCD cameras, to obtain best public view field, for obtaining the visual angle of CCD camera in the actual detected, need make the CCD camera vertical with a plane, adjust the distance of CCD camera and body structure surface, make clear picture, and allow the optical axis of CCD camera point to cross center on the plane, and allow the optical axis of CCD camera point to cross center on the plane, on the orthogonal direction in cross center, place two scales, take pictures then, according in the image the distance of the scale that can photograph, can calculate the CCD camera in the horizontal direction with vertical direction on the visual angle, last parallax range according to two CCD cameras, the angle of video camera and baseline and the visual angle of video camera just can calculate the public view field of two CCD detection systems;

(2) the unique point spatial coordinates calculation method of two CCD detection methods:

As shown in Figure 2, two CCD cameras are watched body structure surface unique point P at synchronization, use left and right sides CCD camera to obtain the image that P is ordered respectively, and their image coordinate is respectively P _l=(X _l, Y _l), P _r=(X _r, Y _r), when two CCD image of camera planes on same plane, then the Y coordinate of the image coordinate of unique point P is identical, i.e. Y _Left=Y _Right=Y is obtained by the perspective transform principle:

$X_{\mathrm{left}}=f\frac{x_c}{z_c}$ $X_{\mathrm{right}}=f\frac{(x_c-B)}{z_c}$ $Y=f\frac{y_c}{z_c}$

Then the time difference is: Disparity=|X _Left-X _Right|=X _Left-X _Right

Can calculate the volume coordinate of structured surface features point under two CCD detection system coordinate systems thus is:

$\left\{\begin{array}{c}{x}_c=\frac{B\·X_l}{\mathrm{Disparity}}\\ y_c=\frac{B\·Y}{\mathrm{Disparity}}\\ z_c=\frac{B\·f}{\mathrm{Disparity}}\end{array}\right.$

As long as the match point that a bit can find correspondence arbitrarily in right CCD camera image planes therefore on the left CCD phase machine side, be that the two is the point of space same point on the CCD camera of the left and right sides, just can determine the volume coordinate of the apparent defect characteristic point of structure according to the intrinsic geometrical constraint of two CCD cameras, this kind method is point-to-point computing, as long as have a few on the image and have match point, just can participate in above-mentioned computing, thereby obtain the apparent defect characteristic point of structure volume coordinate, thereby it is higher to measure efficient.

(3) matching process of the apparent defect image unique point of structure:

The coupling of visual defects image characteristic point is the method by images match, seek out in two width of cloth images mutual corresponding relation between the unique point, thereby determine the same unique point coordinate in two width of cloth images respectively, the characteristic matching of defect image need be carried out feature extraction to two width of cloth visual defects images, can adopt Harris angle point extraction algorithm, SUSAN angle point extraction algorithm or SIFT feature point extraction algorithm;

Obtaining the coordinate time of image, can adopt two kinds of methods of interactive identification and automated characterization coupling, the advantage of interactive identification is to find same unique point exactly in two views, shortcoming is the coordinate that can not determine accurately a little, the automated characterization coupling is to utilize the extraction of unique point and matching algorithm that unique point is accurately located, but the matching result of unique point not necessarily can match the key position of defective, therefore can carry out the coupling of unique point earlier by automatic matching method, can not reach requirement as matching result, the method that re-uses interactive identification is mated

In two CCD detection methods, the coupling of character pair point mainly is the similarity degree of geometric primitive such as two width of cloth image mid points, edge or zone, projected to the image coordinate of the corresponding point that form in two width of cloth images again by same unique point respectively, just can go out the volume coordinate of unique point according to the calculated with mathematical model of two CCD detection methods;

(4) assessment method of the apparent flaw size of structure:

After the volume coordinate that gets access to the apparent defect characteristic point of structure, the length of defective just can be tried to achieve by 2 distance in the space, and the coordinate of establishing in the space at 2 is respectively P ₁(X ₁, Y ₁, Z ₁), P ₂(X ₂, Y ₂, Z ₂), then the length computation formula is:

$L=\sqrt{{(X_1-X_2)}^2+{(Y_1-Y_2)}^2+{(Z_1-Z_2)}^2}$

The depth survey of defective at first needs to set up a measuring basis face, the degree of depth of being asked is with respect to this reference field, this reference field is the space, can utilize the unique point in the three dimensions, try to achieve this space plane according to the computing formula of space plane, the coordinate of establishing three points in the space is respectively P ₁(X ₁, Y ₁, Z ₁), P ₂(X ₂, Y ₂, Z ₂), P ₃(X ₃, Y ₃, Z ₃), then the space plane equation is:

[(Y ₁Z ₂+Y ₂Z ₃+Y ₃Z ₁)-(Y ₃Z ₂+Y ₂Z ₁+Y ₁Z ₃)]X

+[(X ₁Z ₂+X ₂Z ₃+X ₃Z ₁)-(X ₂Z ₂+X ₂Z.+X ₁Z ₃)]Y

+[(X ₁Y ₂+X ₂Y ₃+X ₃Y ₁)-(X ₃Y ₁+X ₂Y ₁+X ₃Y3)]Z

+[(X ₁Y ₂Z ₃+X ₂Y ₃Z ₁+X ₃Y ₁Z ₃)-(X ₃Y ₂Z ₁+X ₂Y ₁Z ₃+X ₁Y ₃Z ₂)]＝0

(Y ₁Z ₂+Y ₂Z ₃+Y ₃Z ₁)-(Y ₃Z ₂+Y ₂Z ₁+Y ₁Z ₃)＝A

(X ₁Z ₂+X ₂Z ₃+X ₃Z ₁)-(X ₂Z ₂+X ₂Z.+X ₁Z ₃)＝B

Order

(X ₁Y ₂+X ₂Y ₃+X ₃Y ₁)-(X ₃Y ₁+X ₂Y ₁+X ₃Y ₃)＝C

(X ₁Y ₂Z ₃+X ₂Y ₃Z ₁+X ₃Y ₁Z ₃)-(X ₃Y ₂Z ₁+X ₂Y ₁Z ₃+X ₁Y ₃Z ₂)＝D

Then plane equation is AX+BY+CZ+D=0,

If coordinates of spatial points is K (X _k, Y _k, Z _k), then spatial point to the distance of space plane is:

$d=\frac{|\mathrm{Aa}+\mathrm{Bb}+\mathrm{Cc}-D|}{\sqrt{A^2+B^2+C^2}}$

Calculate length, width and the depth information of structure visual defects thus,

As long as therefore obtained spatial point coordinate in image, just can calculate the three-dimensional coordinate of spatial point, and then try to achieve the relative position relation of spatial point, also just finished the assessment of impairments of civil engineering structure visual defects.

A kind of two CCD detection systems for the evaluation of civil engineering structure visual defects detect evaluation software by two CCD cameras, support, two-way image pick-up card, computing machine and visual defects and form, wherein two CCD cameras are rack-mount, two CCD cameras are wired on the two-way image pick-up card, the two-way image pick-up card is installed on computers, is detected the acquisition process evaluation of evaluation software control detection system implementation structure visual defects image by visual defects; Described pair of CCD camera model performance is identical, have than the control of high image resolution and automatic gain and bias light automatic compensation function, and optical lens size and ccd sensor size must mate, and interface type mates, and is mega pixel level camera lens; Described support can be installed two CCD cameras, and symmetria bilateralis and can drawing close to the center simultaneously can realize level and the pitch rotation of each camera; Described two-way image pick-up card can be analog acquisition card or digital collection card, and interface type can be IEEE1394, PCI-Express or USB2.0.Visual defects of the present invention detects evaluation software is realized two-way picture synchronization collection, demonstration processing, characteristic matching, assessment of impairments and interactive identification by computer control function, according to the visual defects three-dimensional dimension of visual defects evaluation algorithm measurement structure, and provide structure apparent defects detection report.

In this enforcement, in conjunction with Fig. 3, according to structure actual detected demand, adjust the distance between two CCD camera supports and the tested body structure surface, the rotary optical camera lens makes two CCD phase functions demonstrate the picture rich in detail of the tested defective of body structure surface simultaneously.Computing machine detects evaluation software two-way by visual defects and gathers the apparent defect image of tested structure synchronously, and reading images conversion storage shows, is handled feature point extraction and the coupling that realizes two CCD defect images by the defect image matching algorithm; Calculate the 3 d space coordinate of defect image unique point according to two CCD detection algorithms, and evaluate the size of structure visual defects by geometric relationship.For the apparent crack defect of structure, can evaluate algorithm measurement crackle width by defect damage, evaluation crackle straight length or length of curve; For the apparent planar defective of structure, except length, width and the degree of depth three-dimensional dimension of measuring defective, also can evaluate the defect geometry area, and the examining report of measurand visual defects is provided automatically.

Claims (1)

1. one kind is used for two CCD detection methods that the civil engineering structure visual defects is evaluated, and it is characterized in that method is as follows:

(1) structure configuration method of the two CCD detection systems of visual defects:

In order to obtain the volume coordinate of the apparent defect characteristic point of structure from two dimensional image, two CCD cameras need to obtain two width of cloth images that comprise the apparent defect characteristic point of structure from diverse location; With two CCD cameras intersect from different perspectives put observation same testee, at first to determine the visual angle of single CCD camera, actual conditions of using at engineering then, design parallax range B and angle α between two CCD cameras, to obtain best public view field, for obtaining the visual angle of CCD camera in the actual detected, need make the CCD camera vertical with a plane, adjust the distance of CCD camera and body structure surface, make clear picture, and allow the optical axis of CCD camera point to cross center on the plane, on the orthogonal direction in cross center, place two scales, take pictures then, according in the image the distance of the scale that can photograph, calculate the CCD camera in the horizontal direction with vertical direction on the visual angle, last parallax range according to two CCD cameras, the visual angle of the angle of CCD camera and baseline and CCD camera just can calculate the public view field of two CCD detection systems;

(2) the unique point spatial coordinates calculation method of two CCD detection methods:

Two CCD cameras are watched body structure surface unique point P at synchronization, use left and right sides CCD camera to obtain the image that P is ordered respectively, and their image coordinate is respectively P _l=(X _l, Y _l), P _r=(X _r, Y _r), when two CCD image of camera planes on same plane, then the Y coordinate of the image coordinate of unique point P is identical, i.e. Y _Left=Y _Right=Y is obtained by the perspective transform principle:

Then parallax is: Disparity=|X _Left-X _Right|=X _Left-X _Right

Calculating the volume coordinate of structured surface features point under two CCD detection system coordinate systems thus is:

As long as the match point that a bit can find correspondence arbitrarily in right CCD camera image planes therefore on the left CCD phase machine side, be that the two is the point of space same point on the CCD camera of the left and right sides, just can determine the volume coordinate of the apparent defect characteristic point of structure according to the intrinsic geometrical constraint of two CCD cameras, this kind method is point-to-point computing, as long as have a few on the image and have match point, just can participate in above-mentioned computing, thereby obtain the apparent defect characteristic point of structure volume coordinate, thereby it is higher to measure efficient;

(3) matching process of the apparent defect image unique point of structure:

The coupling of visual defects image characteristic point is the method by images match, seek out in two width of cloth images mutual corresponding relation between the unique point, thereby determine the same unique point coordinate in two width of cloth images respectively, the characteristic matching of defect image need be carried out feature extraction to two width of cloth visual defects images, adopts Harris angle point extraction algorithm, SUSAN angle point extraction algorithm or SIFT feature point extraction algorithm;

Obtaining the coordinate time of image, adopting two kinds of methods of interactive identification and automated characterization coupling, carrying out the coupling of unique point earlier by automatic matching method, can not reach requirement as matching result, the method that re-uses interactive identification is mated,

In two CCD detection methods, the coupling of character pair point mainly is the similarity degree of the geometric primitive in two width of cloth image mid points, edge or zone, projected to the image coordinate of the corresponding point that form in two width of cloth images again by same unique point respectively, just can go out the volume coordinate of unique point according to the calculated with mathematical model of two CCD detection methods;

(4) assessment method of the apparent flaw size of structure:

After the volume coordinate that gets access to the apparent defect characteristic point of structure, the length of defective is just tried to achieve by 2 distance in the space, and the coordinate of establishing in the space at 2 is respectively P ₁(X ₁, Y ₁, Z ₁), P ₂(X ₂, Y ₂, Z ₂), then the length computation formula is:

The depth survey of defective at first needs to set up a measuring basis face, the degree of depth of being asked is with respect to this reference field, this reference field is the space, utilize the unique point in the three dimensions, try to achieve this space plane according to the computing formula of space plane, the coordinate of establishing three points in the space is respectively P ₁(X ₁, Y ₁, Z ₁), P ₂(X ₂, Y ₂, Z ₂), P ₃(X ₃, Y ₃, Z ₃), then the space plane equation is:

[(Y ₁Z ₂+Y ₂Z ₃+Y ₃Z ₁)-(Y ₃Z ₂+Y ₂Z ₁+Y ₁Z ₃)]X

+[(X ₁Z ₂+X ₂Z ₃+X ₃Z ₁)-(X ₂Z ₂+X ₂Z ₁+X ₁Z ₃)]Y

+[(X ₁Y ₂+X ₂Y ₃+X ₃Y ₁)-(X ₃Y ₁+X ₂Y ₁+X ₃Y ₃)]Z

+[(X ₁Y ₂Z ₃+X ₂Y ₃Z ₁+X ₃Y ₁Z ₃)-(X ₃Y ₂Z ₁+X ₂Y ₁Z ₃+X ₁Y ₃Z ₂)]＝0

(Y ₁Z ₂+Y ₂Z ₃+Y ₃Z ₁)-(Y ₃Z ₂+Y ₂Z ₁+Y ₁Z ₃)＝A

(X ₁Z ₂+X ₂Z ₃+X ₃Z ₁)-(X ₂Z ₂+X ₂Z ₁+X ₁Z ₃)＝B

Order

(X ₁Y ₂+X ₂Y ₃+X ₃Y ₁)-(X ₃Y ₁+X ₂Y ₁+X ₃Y ₃)＝C

(X ₁Y ₂Z ₃+X ₂Y ₃Z ₁+X ₃Y ₁Z ₃)-(X ₃Y ₂Z ₁+X ₂Y ₁Z ₃+X ₁Y ₃Z ₂)＝D

Then plane equation is AX+BY+CZ+D=0,

If coordinates of spatial points is K (X _k, Y _k, Z _k), then spatial point to the distance of space plane is:

Calculate length, width and the depth information of structure visual defects thus,

As long as therefore obtained the coordinate of spatial point in image, just can calculate the three-dimensional coordinate of spatial point, and then try to achieve the relative position relation of spatial point, also just finished the assessment of impairments of civil engineering structure visual defects.

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