CN101975556B - Method for measuring distortion of tall chimney based on outline - Google Patents

Abstract

The invention discloses a method for measuring distortion of a tall chimney based on an outline, which comprises the following steps of: (A) capturing the outline of the chimney by using a total station with a digital camera, and ensuring overlapping of two adjacently captured photos for the same outline of the chimney in a vertical direction; (B) quickly extracting the chimney outline in an image; (C) calculating an initial value of a chimney center; (D) selecting the most appropriate photo projected by a space section circle of a given height according to the initial value of the chimney center and known station coordinates; and (E) acquiring the initial value of iterative computation and carrying out the iterative computation on coordinates of the center of a circle and a radius of the space section circle. By the method, horizontal displacement monitoring for the chimney can be quickly realized, the precision is high, and the condition whether the method satisfies requirements or not can be judged through the circumstance whether the coordinates of the center of the circle and the radius of each section circle of the chimney can be quickly measured or not.

Description

Chimney stalk deformation measurement method based on outline line

Technical field

The invention belongs to the engineering survey field, relate to a kind of precise monitoring chimney deformation method.

Background technology

Along with the development of China's cause of modernization, increasing high-rise rises.And chimney has great significance to commercial production as one of representative of high-rise.Skyscraper is that modernization construction is produced when serving, and also exists security risk, in case meet accident, will cause an immeasurable loss to people's life and national wealth.Engineering project deformation observation is the assurance of high-rise building safe reliability service, so the superelevation chimney must regularly carry out safety monitoring.Electric power is the basic need of China's productive life, and at present the electric power of China 80% is from thermoelectricity, and the chimney requisite buildings that is thermal power station.For guaranteeing the safety in production of thermal power plant, guarantee the regular supply of electric power, what a whole set of system must be arranged is out of shape the method and the flow process of carrying out periodic monitoring to chimney accurately.

Compare with common high-rise, chimney has certain singularity, has strengthened the difficulty of deformation observation.Characteristics have: 1, can't directly measure the chimney center.The distortion of monitoring chimney mainly is the horizontal shift of monitoring chimney center line, and center line is not visual, can only measure indirectly.2, rough surface, a little less than the reflection echo, can't be directly with total station survey surface point coordinate.3, texture information lacks, the no marks point.General high-rise can obtain the volume coordinate of monumented point through intersection, judges the horizontal shift of buildings through the level in-migration of monumented point.

At present in the engineering survey, the deformation monitoring of chimney still not being had comparatively perfect method, generally all is the circle that each horizontal section of supposition chimney is a rule, adopts the method intersection space central coordinate of circle of observation chimney outline line.As shown in Figure 1; Observe the profile of the same sectional layer of chimney simultaneously through a plurality of websites, each time observation is regarded as one looks, three stations have six and look among Fig. 1; By the straight-line equation that horizontal angle and website coordinate can be calculated each bar sight line, this straight line is round tangent line.Repeatedly observation, many sight lines can be determined an incircle, and the center of circle i.e. the centre coordinate of section chimney for this reason.Conventional method is tight in theory, can in actual chimney is measured, be difficult to operation.Because the complicacy on chimney surface, can't accomplish that each looks being seen chimney profile all on same sectional layer, be imprecise so adopt this kind method in the actual job.Another drawback that the tradition chimney is measured is that the monitoring amount and the required section number of plies of obtaining are directly proportional, and when obtaining the coordinate of putting on the chimney center line, so that during Accurate Analysis center line deformation trend, workload is huge with needing comparatively dense.

To the limitation of classic method,, a kind of chimney stalk deformation measurement method based on outline line is proposed at present in conjunction with photogrammetric Theory and computer vision technique.This method can solve problem in the chimney measurement preferably.This method still with chimney abstract be one by one section circle, with section circular projection to image, with the ellipse that obtains a rule; Extract the outline line of the chimney on the image, with obtaining one section smooth continuous curve; According to the photography geometrical principle, the point of contact of sight line and space circle must be positioned on the outline line in the projection on the image, constitutes the constraint to space circle thus.Same position can take chimney about two outline lines, change camera positions, can constitute more constraint.A given space section circle elevation can obtain round home position and the radius of this section in the chimney.Different elevation in the given chimney can obtain space section circles different in the chimney, and section circle in numerous space constitutes the surface model of chimney.

Summary of the invention

In the chimney stalk deformation measurement method based on outline line proposed by the invention, the measuring principle basic thought is following:

Adopt the total powerstation of band digital camera based on the chimney stalk deformation measurement method of outline line, open up TOPCON Image Station (being called for short IS) the 201 image total powerstations of general Kanggong department production like Japan and measure.IS can realize photographing and obtain the s internal and external orientation of image simultaneously with digital camera and total powerstation organic integration together.Ultimate principle be with space section circular projection to image, will obtain the ellipse of a rule, and according to the photography geometric knowledge, the point of contact that sight line and space section are justified must be arranged in the outline line of chimney on the image in the projection on the image.Guarantee the subpoint of point of contact on image and the distance minimum of image chimney outline line; At least three observations (i.e. three sight lines) can be made the centre coordinate of space circle, and (X Y) and radius R, generally has redundant observation; Look left and right sides least square for eight, promptly can accurately make the centre coordinate of space circle.

As shown in Figure 2, to establish chimney space section circle and be circle O, space survey station point is S, SZ is direction straight up.Plane, circle O place is a surface level, and obviously along the Z negative direction, it establishes its projection circle for circle O ' just round through being projected as on the surface level of website S, establishes SL ' ₁Be the tangent line of circle O ', the point of contact is A ', and O ' A ' ⊥ SL ' is then arranged ₁If A is a point before A ' projection, then have AA ' //SZ, so some A on the plane L ₁' SZ is last.By AA ' //OO ' can get AA ' OO ' coplane.SL ' ₁⊥ O ' A ', SL ' ₁⊥ OO ' can get SL ' ₁Perpendicular to plane AA ' OO ', so SL ' ₁⊥ OA can draw OA plane L by OA ⊥ SZ again ₁' SZ.Point on the outline line that so OA ⊥ SA, A point are on the image to be seen, all A point projections on image promptly constitute outline line.So sight line SL ₁Be equivalent to by the tangent line SL ' that belongs to the projection circle O ' of surface level through website S to space circle O straight down at website S with " point of contact " A (accurately saying so) planimetric coordinates of space circle through vertical guide and the tangent point of contact of space section circle of website S ₁Planimetric coordinates with the point of contact A ' that justifies O '.

Calculate for convenient, like Fig. 3, we select website S is vertically projected to the mode on plane, section circle place, space; If the space circle center of circle is O, S is a photo centre, and D is the projection of S on plane, space circle place; A, 2 of C are sight line and round point of contact, on image, show as the profile of chimney.The profile of chimney is the set of A point projection on image on the image.In Fig. 3, establishing the O point coordinate is (X ₀, Y ₀, Z ₀), then A, C two point coordinate can be expressed as

A：(X ₀+Rcosθ ₁，Y ₀+Rsinθ ₁，Z ₀) ①

C：(X ₀+Rcosθ ₂，Y ₀+Rsinθ ₂，Z ₀)

Straight line AO is vertical with AD; Then there is

straight line CO vertical, then arranged promptly with CD

$\left[\begin{array}{ccc}{R\cos \mathrm{\θ}}_1& R{\sin \mathrm{\θ}}_1& 0\end{array}\right]\left[\begin{array}{c}{X}_0+R\cos {\mathrm{\θ}}_1-X_s\\ Y_0+R\sin {\mathrm{\θ}}_1-Y_s\\ 0\end{array}\right]=0$ ②

$\left[\begin{array}{ccc}{R\cos \mathrm{\θ}}_2& R{\sin \mathrm{\θ}}_2& 0\end{array}\right]\left[\begin{array}{c}{X}_0+R\cos {\mathrm{\θ}}_2-X_s\\ Y_0+R\sin {\mathrm{\θ}}_2-Y_s\\ 0\end{array}\right]=0$

2. can get by formula, work as X _s＞=X ₀The time:

θ ₁＝b-(π/2-a) ③

θ ₂＝b+(π/2-a)

Work as X _s＜X ₀The time

θ ₁＝π+b-(π/2-a) ④

θ ₂＝π+b+(π/2-a)

Wherein

$a=\arcsin (R/\sqrt{{(X_0-X_s)}^2+{(Y_0+Y_s)}^2})$ ⑤

b＝arctan((Y _s-Y ₀)/(X _s-X ₀))

1. 2. 3. 4. 5. can know by formula, if the position (X of known spatial circle ₀, Y ₀, Z ₀) and radius R, the position (X of photo centre _s, Y _s, Z _s), can obtain θ ₁And θ ₂, and then obtain the volume coordinate of A, C.

Photogrammetric collinearity equation expression formula is following:

$x-x_0=-f\frac{a_1(X-X_s)+b_1(Y-Y_s)+c_1(Z-Z_s)}{a_3\left({X-X}_s\right)+b_3(Y-Y_s)+c_3(Z-Z_s)}$

$y-y_0=-f\frac{a_2(X-X_s)+b_2(Y-Y_s)+c_2(Z-Z_s)}{a_3\left({X-X}_s\right)+b_3(Y-Y_s)+c_3(Z-Z_s)}$

Can be to image according to collinearity equation with A, C two spot projections.

$x_A=-f\frac{U}{W}+x_0$

$y_A=-f\frac{U}{W}+y_0$

$x_C=-f\frac{L}{N}+x_0$

$y_C=-f\frac{M}{N}+y_0$

Wherein

U＝a ₁(X ₀+Rcosθ ₁-X _s)+b ₁(Y ₀+Rsinθ ₁-T _s)+c ₁(Z ₀-Z _s)

V＝a ₂(X ₀+Rcosθ ₁-X _s)+b ₂(Y ₀+Rsinθ ₁-Y _s)+c ₂(Z ₀-Z _s)

W＝a ₃(X ₀+Rcosθ ₁-X _s)+b ₃(Y ₀+Rsinθ ₁-Y _s)+c ₃(Z ₀-Z _s) ⑧

L＝a ₁(X ₀+Rcosθ ₂-X _s)+b ₁(Y ₀+Rsinθ ₂-Y _s)+c ₁(Z ₀-Z _s)

M＝a ₂(X ₀+Rcosθ ₂-X _s)+b ₂(Y ₀+Rsinθ ₂-Y _s)+c ₂(Z ₀-Z _s)

N＝a ₃(X ₀+Rcosθ ₂-X _s)+b ₃(Y ₀+Rsinθ ₂-Y _s)+c ₃(Z ₀-Z _s)

(x _A, y _A) and (x _C, y _C) be observed reading, X ₀, Y ₀Be unknown number to be asked with R.Given X ₀, Y ₀With the initial value of R, can calculate A, 2 coordinate (x on image of C _A, y _A) and (x _C, y _C), think distance (x on the outline line _A, y _A) and (x _C, y _C) nearest point is 2 true coordinate on image, with its relatively and find the solution, can obtain X ₀, Y ₀With the reduction of R, thereby iteration is obtained the actual position and the radius of space circle according to this.

7. formula linearization is got error equation

V＝AX-L ⑨

Wherein

$V={\left[\begin{array}{cccc}{V}_{x_A}& V_{y_A}& V_{x_c}& V_{x_c}\end{array}\right]}^T$

$A=\left[\begin{array}{ccc}F(a_{3}U-a_{1}W)& F(b_{3}U-b_{1}W)& F((a_{3}U-a_{1}W)\cos {\mathrm{\θ}}_1+(b_{3}U-b_{1}W)\sin {\mathrm{\θ}}_1)\\ F(a_{3}V-a_{2}W)& F(b_{3}V-b_{2}W)& F((a_{3}V-a_{2}W)\cos {\mathrm{\θ}}_1+(b_{3}V-b_{2}W)\sin {\mathrm{\θ}}_1)\\ T(a_{3}L-a_{1}N)& T(b_{3}L-b_{1}N)& T((a_{3}L-a_{1}N)\cos {\mathrm{\θ}}_2+(b_{3}L-b_{1}N)\sin {\mathrm{\θ}}_2)\\ T(a_{3}M-a_{2}N)& T(b_{3}M-b_{2}N)& T((a_{3}M-a_{2}N)\cos {\mathrm{\θ}}_2+(b_{3}M-b_{2}N)\sin {\mathrm{\θ}}_2)\end{array}\right]$

X＝[dX ₀?dY ₀?dR] ^T

$L={\left[\begin{array}{cccc}{d}_{x_A}& d_{y_A}& d_{x_C}& d_{y_C}\end{array}\right]}^T$

$F=\frac{f}{{\mathrm{<figure-callout\; id="2"\; label="W"\; filenames="101013151040.png"\; state="\{\{state\}\}">W</figure-callout>}}^2}$

$T=\frac{\mathrm{<figure-callout\; id="2"\; label="f\; N"\; filenames="101013151040.png"\; state="\{\{state\}\}">f</figure-callout>}}{N^{}}$

10. can get based on the principle of least square by formula

X＝(A ^TA) ^-1A ^TL

In fact, each website can have two sight lines, promptly observes A point and C point.The constraint condition of every sight line has only one, and promptly the subpoint distance profile linear distance of point of contact, space on image is minimum.So each is looked and has only an observed reading.At least need 3 sight lines just can obtain the X of space circle in theory ₀, Y ₀And R.But consider the reliability of redundant observation and net form, at least three survey stations of general recommendations evenly distribute around chimney.

The present invention uses this principle, provides the complete chimney stalk deformation measurement method of a cover, comprises the steps:

A. with the total powerstation of band digital camera, take the profile of chimney, same outline line of chimney adjacent taken photograph for twice guarantee to have on the vertical direction overlapping, degree of overlapping 50% is the most suitable;

B. the rapid extraction of chimney outline line in the image;

C. the calculating of chimney center initial value;

D. according to chimney center initial value with select the only photograph at given elevation space section circular projection place with known survey station coordinate;

E. obtaining of iterative computation initial value, round heart coordinate of iterative computation space section and radius.

The rapid extraction of said chimney outline line comprises: (1) marginal point extracts; (2) RANSAC fitting a straight line; (3) outline line is confirmed.

The calculating of said chimney center initial value comprises:

1) in each survey station, calculate in the revolver profile image sequence corresponding horizontal angle median mean value in the corresponding horizontal angle median and right outline line image sequence, this value thinks that the survey station center arrives the horizontal angle at chimney center;

2) according to survey station central horizontal coordinate and corresponding horizontal angle, intersection draws chimney central horizontal coordinate initial value.

Round heart coordinate of said iterative computation space section and radius comprise: angle θ and corresponding point of contact A or C volume coordinate are confirmed in (1); (2) calculate the subpoint coordinate of point of contact on image; (3) row error equation, adjustment; (4) if the unknown number correction less than given threshold value, the unknown numerical value after the correction is as the iteration net result, iteration finishes, otherwise,, change (1) as the next iteration initial value with the unknown numerical value after correcting.

Compare with current methods, the method has theoretical tight, and method is simple; Precision can pre-estimation before surveying, and instructs and establishes the station; The achievement precision is high; Achievement is continuous; Application of result is abundant; Monitoring efficient is high; The low seven big advantages of monitoring cost.

Description of drawings

Fig. 1 tradition intersection circule method is surveyed the center of circle.

Fig. 2 space section circular projection synoptic diagram.

Section circle point of contact, Fig. 3 space synoptic diagram.

Fig. 4 chimney is measured operation process chart.

Industry flow chart of data processing figure in Fig. 5.

Fig. 6 outline line extracts process flow diagram automatically.

Fig. 7 iterative algorithm process flow diagram.

Fig. 8 field operation shooting process figure.

Convolution template during Fig. 9 chimney outline line extracts.

Embodiment

Introduce the present invention in detail below in conjunction with accompanying drawing and embodiment.

Be the concrete steps that chimney is measured below:

One, field data obtains, and step is following:

1, field operation is laid the reference mark, and the reference mark evenly distributes around chimney, and is moderate with the chimney mean distance, estimates the achievement precision, guarantees the reference mark laying rationally.Each reference mark volume coordinate is measured in control survey.

2, set up IS total powerstation and rearscope, leveling centering, orientation by backsight.Carry out the shooting of image after directed the completion, at first total powerstation is sighted chimney revolver profile, at the bottom of chimney pushes up chimney, take successively, basic demand is that adjacent twice shooting photograph guarantees on the vertical direction 50% degree of overlapping is arranged, intact continuously of sequence image.Then total powerstation is sighted the right outline line of chimney, repeat shooting process, shooting process is as shown in Figure 8.As with the difference of general total powerstation, take accomplish after, the automatic recording image of IS total powerstation and every information such as s internal and external orientation that image is corresponding, the raw data of handling as industry in follow-up.

3, select three survey stations at least, repeat 2 processes.

Two, field data engineering management, step is following:

1, imports each survey station data, in every survey station, be written into the primary data information (pdi) of IS total powerstation record, reject invalid image.

2, generate the thumbnail of effective image, be convenient to browse and check.

3, in every survey station, distinguish left and right wheels profile image and ordering.

Three, the chimney outline line extracts in the image, and step is following:

1, with mask convolution image shown in Figure 9, general n gets 21 or 25, uses recursive algorithm to improve convolution efficiency, and the maximum pixel of convolution and mould is similar to and thinks point on the outline line in the every row of image.

2, use the RANSAC algorithm in 1, to detect approximate contours line point fitting a straight line L.

3, be initial value with straight line L, use the center of gravity process of iteration to get accurate outline line point.

4, outline line is done smoothing processing, obtain final outline line point.

Four, inspection of chimney outline line and editor.The inspection outline line extracts the result, and apparent error is extracted the result, adopts human-edited's mode modified profile line.

Five, chimney center initial value is estimated, step is following:

1, in each survey station, calculate in the revolver profile image sequence corresponding horizontal angle median mean value in the corresponding horizontal angle median and right outline line image sequence, this value thinks that the survey station center arrives the horizontal angle at chimney center.

2, repeat 1 step, calculate the horizontal angle of all survey station centers to the chimney center.

3, according to survey station central horizontal coordinate and corresponding horizontal angle, intersection draws chimney central horizontal coordinate initial value.

Six, photograph is selected, and step is following:

1, according to given chimney section circle height value and chimney center initial value; In each survey station; Survey station coordinate Calculation by known goes out the near normal angle, in revolver profile image sequence, screens the immediate image of corresponding vertical angle and near normal angle; If two angle angles, think then that this image is for confirming elevation section circular projection place image less than limit poor (1/2 vertical field of view angle).Corresponding right outline line image in like manner can get.

2, repeat 1 step, select space section circle only left and right wheels profile image in each survey station.

Seven, iterative initial value is estimated, step is following:

1, according to the photograph of selecting in the step 6, confirm plane and straight line by this survey station center, photograph place and the corresponding horizontal angle of this photograph, N (N＞=3) width of cloth photograph can be confirmed N bar straight line.

2,, obtain flat coordinate of the round edema with the heart involved of space section and radius initial value by N bar lines enveloping clearancen discontinuity surface circle in 1.

Eight, round heart coordinate of iterative computation space section and radius, step is following:

1,,,, calculates angle θ if this image is a revolver profile image according to the iterative initial value in the step 7 for each width of cloth image in the step 6 ₁With point of contact A volume coordinate.If this image is right outline line image, calculate angle θ ₂With point of contact C volume coordinate.

2,, calculate the subpoint coordinate (x of point of contact A (right outline line image should be C mutually) by the corresponding s internal and external orientation of image _A, y _A).

3, because the outline line near normal in image X axle, so with the image X axis apart from the replacement (x _A, y _A) to the actual range of outline line.Interior inserting obtained corresponding y _AThe point of outline line

Order

For right outline line image, corresponding A replaces with C.

4, according to principle described in the background technology, each width of cloth image in the treatment step six is listed error equation.

5, the unknown number correction is found the solution in compensating computation.If the unknown number correction is less than given threshold value, the unknown numerical value after the correction is as the iteration net result, and iteration finishes, otherwise, as the next iteration initial value, change 1 with the unknown numerical value after correcting.

Subsequent analysis and processing.To monitoring result, do subsequent analysis and decision-making.

Claims (4)

1. the chimney stalk deformation measurement method based on outline line is characterized in that comprising the steps:

A. with the total powerstation of band digital camera, take the profile of chimney, have overlapping on the adjacent twice shooting photograph assurance vertical direction to same outline line of chimney;

B. the rapid extraction of chimney outline line in the image;

C. in every survey station, calculate in the revolver profile image sequence corresponding horizontal angle median mean value in the corresponding horizontal angle median and right outline line image sequence, this value thinks that the survey station center arrives the horizontal angle at chimney center; Obtain all survey station centers successively after the horizontal angle at chimney center, according to survey station central horizontal coordinate and corresponding horizontal angle, intersection draws chimney central horizontal coordinate initial value;

D. according to given chimney section circle height value and chimney center initial value, in each survey station, go out the near normal angle by known survey station coordinate Calculation; In this survey station left and right wheels profile image sequence, screen the immediate image of corresponding vertical angle and near normal angle respectively,, think that then this image is this section circle optimum image in the outline line image sequence if two angle angles are poor less than limit; Select this space section circle only left and right wheels profile image in each survey station successively;

E. obtaining of iterative computation initial value, round heart coordinate of iterative computation space section and radius.

2. the chimney stalk deformation measurement method based on outline line as claimed in claim 1, it is characterized in that comprising the rapid extraction of said chimney outline line: (1) marginal point extracts; (2) RANSAC fitting a straight line; (3) outline line is confirmed.

3. a kind of chimney stalk deformation measurement method based on outline line as claimed in claim 1 is characterized in that round heart coordinate of said iterative computation space section and radius, comprising: angle θ and corresponding point of contact A or C volume coordinate are confirmed in (1); (2) calculate the subpoint coordinate of point of contact on image; (3) row error equation, adjustment; (4) if the unknown number correction less than given threshold value, the unknown numerical value after the correction is as the iteration net result, iteration finishes, otherwise,, change (1) as the next iteration initial value with the unknown numerical value after correcting.

4. a kind of chimney stalk deformation measurement method as claimed in claim 1 based on outline line, it is characterized in that to same outline line of chimney adjacent take for twice have on the photograph vertical direction 50% overlapping.

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