CN1995954A - Visual measuring system and method for performance parameter of water-saving toilet bowl - Google Patents

Abstract

The invention relates to single camera water saving toilet performance parameter visual inspection system and method. It comprises camera with orthostigmat, adjusting device, working platform, computer, image sampling card, calibration target, steel rule and ink drawing device. The orthostigmat camera takes the picture of the residue ink line, extracting its image coordinate, calculating the projection coordinate based on the camera model, getting the space measuring coordinate of the residue ink line through the project coordinate based on the math model of the measurement system, and getting the real length of the ink line through the space measuring coordinate. It realizes non-contact automatic measurement with simple operation and high efficiency.

Description

Performance parameter of water-saving toilet bowl vision measurement system and measuring method

Technical field

The invention belongs to field of measuring technique, relate to a kind of performance parameter of water-saving toilet bowl vision measurement system and measuring method based on single camera.

Background technology

Protection, rational utilization of water resources are avoided water loss and waste, are the grand strategy problems that guarantees Chinese national economy and social development.At present, the ceramic-like closet is a kind of important cleaners and polishes that generally use, so the quality of the water-saving performance of ceramic-like closet directly has influence on the state that utilizes of water resource.The amount of flush water that reduces the ceramic-like closet is a kind of effective using water wisely approach, and water consumption is the main product that 6 liters water-saving toilet bowl becomes the closet sanitary equipment gradually.But the water-saving performance of 6 liters of water-saving toilet bowls does not have real authority's mechanism or equipment to test, so the criterion problem in water-saving toilet bowl market needs to be resolved hurrily.

According to the regulation of the city-building industry standard CJ164-2002 of the People's Republic of China (PRC) about " water-saving life appliance standard ", one of method of the washing capacity of detection closet is a line of ink marker test method(s), after requiring each flushing, adopt line of ink marker method, accumulate residual black vestige length overall and be not more than 50mm.Concrete method is: washable surface is dried, and a circle ink line is drawn along washable surface by 25mm place below the closet circle with soft pen, bath immediately, and survey record remains in the line of ink marker length on the washable surface.Hence one can see that, and the accurate measurement of residual line of ink marker length is the key issue of line of ink marker test method(s).Line of ink marker linear measure longimetry at present is by manually operating with observation by rule of thumb, use soft ruler that residual line of ink marker length is measured, because the vestige after the line of ink marker is rinsed is irregular, the mode difference that different checkers detects, measurement result has very big difference, also influenced the accuracy that detects, and efficiency of measurement is low.

Computer vision and Flame Image Process are a kind of important means of free curve linear measure longimetry, have the efficiency of measurement height, and equipment cost is low, and the automaticity advantages of higher is widely used in article geometrical size and measures.Existing article geometrical size based on computer vision is measured and is mainly measured on three dimensions based on the stereovision technique means, and the video camera that requires to be positioned at different angles can observe measurand; Measure mainly based on two-dimensional measurement based on the article geometrical size of Flame Image Process, adopt the single camera measurement to be positioned at article geometrical size on the specific plane, therefore require on measurement plane, to put target, carry out the calibration of picture size and bulk scale factor.The main difficult point of residual line of ink marker linear measure longimetry is, the line of ink marker is a free shape, irregular, the line of ink marker is the 25mm place under the closet circle, being subjected to closet circle edge easily blocks, be difficult to observe from different perspectives whole residual lines of ink marker, be difficult to place the calibration target in addition on line of ink marker plane of living in, and must adopt wide-angle lens.Based on the technological means of three-dimensional measurement, the cost height and the line of ink marker can be observed from different perspectives simultaneously by a plurality of video cameras, so the three-dimensional measurement technological means is difficult to realize the measurement of the residual line of ink marker.Line of ink marker linear measure longimetry based on single camera, must consider the wide-angle lens distortion, and calibration plane and measurement plane are difficult to be in same position, because the driving frequency of the CCD chip of general video camera, the lateral dimension of pixel and vertical dimension is inconsistent and factor such as image acquisition frequency, space object is in imaging process, image is an equivalent not at horizontal, longitudinal direction, in measuring process, must be calibrated.

Summary of the invention

Technical matters to be solved by this invention is: a kind of single camera performance parameter of water-saving toilet bowl vision measurement system and measuring method are provided.Residual line of ink marker length in the performance parameter finger writing or painting thread test of the said water-saving toilet bowl of the present invention, single camera performance parameter of water-saving toilet bowl vision measurement system is made of video camera, adjusting mechanism, worktable, computing machine, image pick-up card, calibration target, Steel Ruler and the line of ink marker drawing apparatus of a band wide-angle lens.According to the mathematical model of single camera performance parameter of water-saving toilet bowl vision measurement system, by the image coordinate of the residual line of ink marker, calculate the volume coordinate of the residual line of ink marker, utilize spatial coordinates calculation to go out the physical length of the residual line of ink marker.With simplified measurement system calibration process, raising calibration accuracy, improve the automaticity of efficiency of measurement and measuring system, improve operability and convenience that its through engineering approaches is used.

Technical solution of the present invention is: a kind of single camera performance parameter of water-saving toilet bowl vision measurement system, it is characterized in that,

1, it is made up of video camera 1, adjusting mechanism, worktable 9, computing machine, image pick-up card, calibration target 10, Steel Ruler 8 and the line of ink marker drawing apparatus of band wide-angle lens 2.Adjusting mechanism is made up of video camera fixed support 3, vertical supports 4, horizontal adjusting lever 5 and turning axle 6.Image pick-up card is installed in the calculating.Video camera is fixed on the vertical supports 4 by video camera fixed support 3.Vertical supports 4 is fixed on the horizontal adjusting lever 5, can move along horizontal adjusting lever direction, and can be around horizontal adjusting lever rotation.Laterally adjusting lever 5 is fixed on the turning axle 6, and can rotate around turning axle 6.Turning axle 6 is fixed on the worktable 9, and water-saving toilet bowl is placed on the worktable 9;

2, the upper surface of choosing video camera fixed support 3 is the reference position, and the scope of installing and measuring is the Steel Ruler 8 of 50cm on video camera fixed support 3, by screw retention, unclamp screw, Steel Ruler 8 can move up and down, and is used for measuring system calibration plane and the measurement plane height parameter to the reference position;

3, said calibration target 10 is a two dimensional surface, the unique point that sets in advance is arranged on the target, arrange chequered with black and white gridiron pattern on the target plane, the length of side of black and white square is 5～50mm, its length of side precision is 0.01mm～0.1mm, and the publicly-owned summit of black box and white square is called lattice point.Choose that lattice point is a unique point on the target surface, unique point quantity is 16～400;

4, said line of ink marker drawing apparatus is made up of slip rail 11, last location-plate 12, following location-plate 13 and soft pen 14, last location-plate 12, following location-plate 13 and soft pen 14 all are screwed on slip rail 11, after unclamping screw, can move along slip rail direction, also can adjust in the horizontal direction simultaneously.When drawing the line of ink marker, actual conditions according to closet, the upper surface of last location-plate 12 being close to closet circle 7, following location-plate 13 is close to the interior lower surface of closet circle 7, tighten up the screw on location-plate 12 and the following location-plate 13, adjust soft pen 14, guarantee that soft pen 11 distances to last location-plate 12 are 25mm along slip rail 11, move line of ink marker drawing apparatus one circle along the closet circle then, just can draw out the line of ink marker in the closet inner wall surface;

Use performance parameter of water-saving toilet bowl vision measurement system as described above to carry out the method that performance parameter of water-saving toilet bowl is measured, it is characterized in that, measuring process is divided into calibration phase and measuring phases, but carries out continuous coverage behind the primary calibration, and concrete steps are as follows:

1, calibration phase:

1.1, water-saving toilet bowl is placed on the worktable, adjust and to install video camera.Use line of ink marker drawing apparatus 25mm place under the closet circle to draw a circle line of ink marker along the closet inner wall surface, line of ink marker width is 3～6mm.By adjusting mechanism, make video camera can observe all lines of ink marker, adjust the lens focus and the aperture of video camera, guarantee that image is comparatively clear.Vertical supports 4, video camera 1 and wide-angle lens 2 are tightened up, and laterally adjusting lever 5 can rotate around turning axle 6;

1.2, the inner parameter of calibration camera 1.Concrete steps are as follows:

The first step, in the field range of video camera, a position is whenever moved in free, 10 at least 3 positions of non-parallel ground moving target mark, takes piece image, is called the camera calibration image, and unique points all on the target should be included in the photographic images;

Second goes on foot, and extracts the image coordinate of the unique point of all camera calibration images, and corresponding with the world coordinates of unique point;

The 3rd step, utilize the image coordinate and the corresponding world coordinate of all unique points of second step extraction to come the calibration camera inner parameter, comprise video camera effective focal length, principal point and distortion factor;

1.3, obtain the video camera external parameter of target in the system calibration planimetric position.Concrete steps are as follows:

The first step is placed target 10 on closet circle 7, choosing the target plane is the system calibration plane, with the vertical height L of Steel Ruler 9 measuring system calibration plane to the reference position _cTake the image of a width of cloth target with video camera, be called the system calibration image, the unique point on the target is called the system calibration unique point, and all system calibration unique points should be included in the photographic images;

Second step, the image coordinate of the system calibration unique point of extraction system calibration image, according to camera model, the projection coordinate of calculated characteristics point, and corresponding with the target coordinate of unique point;

The 3rd step, utilize second to go on foot the projection coordinate of the system calibration unique point of extracting and the external parameter that corresponding target coordinate is estimated video camera, comprise rotation matrix and translation vector;

1.4, remove the water-saving toilet bowl on the worktable, will calibration good intrinsic parameters of the camera, target are at the video camera external parameter of system calibration planimetric position, the calibration plane vertical height L to the reference position _cAnd the target coordinate of system calibration unique point is saved in the systems parameters document, calls in order to measuring phases;

2, measuring phases:

2.1, the water-saving toilet bowl that will measure is placed on the worktable, uses line of ink marker drawing apparatus 25mm place under the closet circle to draw one along the closet inner wall surface and encloses the line of ink marker, line of ink marker width is 3～6mm.By rotating horizontal adjusting lever or moving up and down vertical supports 4, guarantee that video camera can observe all lines of ink marker.Measure the vertical range L of plane, line of ink marker place with Steel Ruler to the reference position _m, calculate the distance L=L of calibration plane to measurement plane _m-L _c

2.2, press the flush valve of closet, the flushing device for toilet that discharges water, treat that bath finishes after, take the image of a residual line of ink marker with video camera, be called line of ink marker measurement image;

2.3, calculate the physical length of the residual line of ink marker, concrete steps are:

The first step is utilized the conversion of target point and projection plane on the target coordinate Calculation measurement plane of the video camera external parameter of system calibration planimetric position and system calibration unique point;

Second step, extract the image coordinate of all residual lines of ink marker of line of ink marker measurement image, the residual line of ink marker is by forming, and the line of ink marker that all consecutive point are formed is labeled as a line of ink marker, and the non-adjacent line of ink marker is labeled as the different lines of ink marker.According to camera model, calculate the projection coordinate of all residual lines of ink marker;

In the 3rd step,,, calculate the measurement coordinate of the residual line of ink marker by the projection coordinate of the residual line of ink marker according to the systematic survey model;

The 4th step, calculates the distance between the adjacent line of ink marker point on same the line of ink marker, and with distance with as the length of this line of ink marker, the length of calculating all residual lines of ink marker with, as final residual line of ink marker linear measure longimetry result;

2.4, remove the water-saving toilet bowl on the worktable, preserve residual line of ink marker linear measure longimetry result;

2.5, repeating step 2.1～2.4, carry out new performance parameter of water-saving toilet bowl and measure.

Advantage of the present invention is:

The first, the present invention has realized the automatic non-cpntact measurement based on the residual line of ink marker length of single camera for the free curve linear measure longimetry provides a kind of high precision non-contact measurement new method;

The second, the present invention has set up calibration plane when parallel with measurement plane, the mathematical model of single camera vision measurement, solved the measurement of closet performance parameter and be difficult to place an alignment target target difficult problem in measurement plane location, the measuring system calibration steps of invention, auxiliary adjustment equipment simple to operate, as to need not complexity;

Three, the single camera dimension measurement method of the present invention's proposition has been realized the pixel size of unique point and the Nonlinear Mapping of space physical size, has reduced the error of bringing according to single scale factor calculation real space size;

Four, Fa Ming line of ink marker drawing apparatus can be drawn out the uniform line of ink marker, and is easy to operate simple;

Five, measuring system is simple to operate, efficiency of measurement is high, and measuring accuracy is higher, the automaticity height;

Description of drawings

Fig. 1 is a single camera performance parameter of water-saving toilet bowl vision measurement system synoptic diagram.Among Fig. 1, the 1st, video camera, the 2nd, wide-angle lens, the 3rd, video camera fixed support, the 4th, vertical supports, the 5th, horizontal adjusting lever, the 6th, turning axle, the 7th, closet circle, the 8th, Steel Ruler, the 9th, worktable.

Fig. 2 is a two dimensional surface target synoptic diagram.Among Fig. 2, the 10th, the target body.

Fig. 3 is a line of ink marker drawing apparatus synoptic diagram.Among Fig. 3, the 11st, slip rail, the 12nd, last location-plate, the 13rd, following location-plate, the 14th, soft pen.

Fig. 4 is the mathematical model synoptic diagram of single camera performance parameter of water-saving toilet bowl vision measurement system.

Embodiment

Below the present invention is described in further details.The present invention is based on computer vision and image processing techniques, use single camera to realize that the on-the-spot of residual line of ink marker length measured automatically in the performance parameter of water-saving toilet bowl measurement.

Performance parameter of water-saving toilet bowl vision measurement system ultimate principle of the present invention as shown in Figure 1, it by the band wide-angle lens 2 video camera 1, adjusting mechanism, worktable 9, computing machine, image pick-up card, calibration target 10, Steel Ruler 8 and line of ink marker drawing apparatus form.Adjusting mechanism is made up of video camera fixed support 3, vertical supports 4, horizontal adjusting lever 5 and turning axle 6.Image pick-up card is installed in the calculating.Video camera is fixed on the vertical supports 4 by video camera fixed support 3.Vertical supports 4 is fixed on the horizontal adjusting lever 5, can move along horizontal adjusting lever direction, and can be around horizontal adjusting lever rotation.Laterally adjusting lever 5 is fixed on the turning axle 6, and can rotate around turning axle 6.Turning axle 6 is fixed on the worktable 9, and water-saving toilet bowl is placed on the worktable 9.

The upper surface of choosing video camera fixed support 3 is the reference position, and the scope of installing and measuring is the Steel Ruler 8 of 50cm on video camera fixed support 3, by screw retention, unclamps screw, Steel Ruler 8 can move up and down, and is used for measuring system calibration plane and the measurement plane height parameter to the reference position.

As shown in Figure 2, said calibration target 10 is a two dimensional surface, the unique point that sets in advance is arranged on the target, on the target plane, arrange chequered with black and white gridiron pattern, the length of side of black and white square is 5～50mm, its length of side precision is 0.01mm～0.1mm, and the publicly-owned summit of black box and white square is called lattice point.Choose that lattice point is a unique point on the target surface, unique point quantity is 16～400.

As shown in Figure 3, said line of ink marker drawing apparatus is made up of slip rail 11, last location-plate 12, following location-plate 13 and soft pen 14, last location-plate 12, following location-plate 13 and soft pen 14 all are screwed on slip rail 11, after unclamping screw, can move along slip rail direction, also can adjust in the horizontal direction simultaneously.When drawing the line of ink marker, actual conditions according to closet, the upper surface of last location-plate 12 being close to closet circle 7, following location-plate 13 is close to the interior lower surface of closet circle 7, tighten up the screw on location-plate 12 and the following location-plate 13, adjust soft pen 14, guarantee that soft pen 11 distances to last location-plate 12 are 25mm along slip rail 11, move line of ink marker drawing apparatus one circle along the closet circle then, just can draw out the line of ink marker in the closet inner wall surface.

The principle of work of residual line of ink marker length vision measurement is: the image of being taken the residual line of ink marker by the video camera of band wide-angle lens, extract the image coordinate of the residual line of ink marker by Flame Image Process, according to camera model, calculate the projection coordinate of the residual line of ink marker, mathematical model according to measuring system, calculate the space measurement coordinate of the residual line of ink marker by the projection coordinate of the residual line of ink marker, by the physical length of the space measurement coordinate Calculation line of ink marker.

The mathematical model of single camera performance parameter of water-saving toilet bowl vision measurement system:

As shown in Figure 4, o _t-x _ty _tz _tBe three-dimensional target coordinate system, o _c-x _cy _cz _cBe three-dimensional camera coordinate system, o _s-x _my _mz _mBe three-dimensional measurement coordinate system, o _u-x _uy _uBe two-dimensional ideal image coordinate system, o _n-x _ny _nBe two-dimensional projection's coordinate system.π _uBe ideal image plane, π _nBe projection plane, π _tBe target plane, o _cBe the projection centre of video camera, o _pBe principal point, o _cTo π _nDistance be 1.Definition o _cx _c//o _ux _u//o _nx _n, o _cy _c//o _uy _u//o _ny _n, o _cz _c π _uAnd π _u// π _nQ _tBe the unique point on the target plane, Q _mBe character pair point on the measurement plane, Q _tQ _m//o _to _m, straight line

Respectively with plane π _nAnd π _uIntersect at a q _nAnd q _u

If π _t// π _m, and π _tWith π _mDistance between the plane is L, then o _mAt o _t-x _ty _tz _tIn coordinate be T _t ^m=[o o L] ^TQ sets up an office _tThree-dimensional target coordinate be X _t=[x _ty _tz _t] ^T, the corresponding three-dimensional camera coordinates is X _c=[x _cy _cz _c] ^T, some Q _mThe three-dimensional measurement coordinate be X _m=[x _my _mz _m] ^T, z wherein _m=0.Then have:

$X_t=I.X_m+T_t^m---\left[1\right]$

$X_c=R_c^t{X}_t+T_c^t---\left[2\right]$

Wherein 1 is 3 * 3 unit matrix, R _c ^tAnd T _c ^tBe o _t-x _ty _tz _tTo o _c-x _cy _cz _cConversion, represent 3 * 3 rotation matrix and 3 * 1 translation vector respectively.

Q sets up an office _nProjection coordinate be X _n=[x _ny _n] ^T, then the desirable perspective projection transformation of video camera is:

$\left\{\begin{array}{c}{x}_n=x_c/z_c\\ y_n=y_c/z_c\end{array}\right.---\left[3\right]$

Q sets up an office _uThe ideal image coordinate be X _u=[x _uy _u] ^TThen projection coordinate to the ideal image transformation of coordinates is:

$\left\{\begin{array}{c}{x}_u=f_x{x}_n+u_0\\ y_u=f_y{y}_n+v_0\end{array}\right.---\left[4\right]$

F wherein _xAnd f _yBe respectively the effective focal length of video camera on x, y direction, unit is a pixel, (u ₀, v ₀) be the principal point coordinate of video camera, unit is a pixel.Consider the distortion of camera lens, q sets up an office _uCorresponding real image coordinate is X _d=[x _dy _d] ^T, then the ideal image coordinate is to the real image transformation of coordinates, and promptly the distortion model of camera lens is:

$\left\{\begin{array}{c}{x}_d=x_u+r^2(k_1+k_2{r}^2)x_u+2p_1{x}_u{y}_u+p_2({\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+2x_u^2)\\ y_d=y_u+r^2(k_1+k_2{r}^2)y_u+p_1({\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">r</figure-callout>}}^2+2y_u^2)+2p_2{x}_u{y}_u\end{array}---\left[5\right]\right.$

Wherein ${\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">r</figure-callout>}}^2=x_{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">u</figure-callout>}}^2+x_{\mathrm{<figure-callout\; id="2"\; label="u"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">u</figure-callout>}}^2,$ k ₁And k ₂Be respectively once and secondary coefficient of radial distortion, p ₁And p ₂Be respectively once and secondary tangential distortion coefficient.

The projection model of video camera has intactly been described in formula [2]～[5], and only image projection point can be determined in the arbitrfary point, space.

Can obtain by formula [1]～[3] that the transformation relation of arbitrfary point and projection plane is on the measurement plane:

$\mathrm{\&rho;}{\tilde{X}}_n=H{\tilde{X}}_m---\left[6\right]$

Wherein p is not equal to 0 scale factor, ${\tilde{X}}_n={\left[x_n{y}_{n}1\right]}^T,$ ${\tilde{X}}_m=[x_m{y}_{m}1{]}^T,$

$H=\left[\begin{array}{ccc}{h}_1& h_2& h_3\\ h_4& h_5& h_6\\ h_7& h_8& {\mathrm{<figure-callout\; id="9"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_9\end{array}\right],$ The expression measurement plane satisfies constraint condition to 3 * 3 transformation matrixs of projection plane:

$\left\{\begin{array}{c}{h}_1^2+{\mathrm{<figure-callout\; id="4"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_4^2+{\mathrm{<figure-callout\; id="7"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_7^2=1\\ {\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_2^2+h_5^2+{\mathrm{<figure-callout\; id="8"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_8^2=1\\ h_1.{\mathrm{<figure-callout\; id="2"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_2+{\mathrm{<figure-callout\; id="4"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_4.h_5+{\mathrm{<figure-callout\; id="7"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_7.{\mathrm{<figure-callout\; id="8"\; label="h"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">h</figure-callout>}}_8=0\end{array}\right.---\left[7\right]$

If video camera and measuring system are through demarcation, then f _x, f _y, (u ₀, v ₀), k ₁, k ₂, p ₁, p ₂Known with matrix H, therefore obtain the image coordinate of unique point on the measurement plane by Flame Image Process, calculate the projection coordinate of unique point by formula [4] and [5], the mathematical model according to formula [6] expression calculates the two-dimensional measurement coordinate of unique point on measurement plane.

Summarize describedly, the model parameter that comprises based on single camera performance parameter of water-saving toilet bowl vision measurement system is: video camera effective focal length f _xAnd f _y, principal point coordinate (u ₀, v ₀), the lens distortion coefficient k ₁, k ₂, p ₁, p ₂Transformation matrix H with measurement plane and projection plane.

According to the mathematical model and the measuring principle of the present invention of performance parameter of water-saving toilet bowl vision measurement system, the vision measurement of residual line of ink marker length is divided into the Measuring System Models parametric calibration and measures two stages according to model.

The concrete steps of Measuring System Models parametric calibration of the present invention are as follows:

1, water-saving toilet bowl is placed on the worktable, adjusts and install video camera.Use line of ink marker drawing apparatus 25mm place under the closet circle to draw a circle line of ink marker along the closet inner wall surface, line of ink marker width is 3～6mm.By adjusting mechanism, make video camera can observe all lines of ink marker, adjust the lens focus and the aperture of video camera, guarantee that image is comparatively clear.Vertical supports 4, video camera 1 and wide-angle lens 2 are tightened up, and laterally adjusting lever 5 can rotate around turning axle 6.

2, the inner parameter of calibration camera 1.Concrete steps are as follows:

The first step, in the field range of video camera, a position is whenever moved in free, 10 at least 3 positions of non-parallel ground moving target mark, takes piece image, is called the camera calibration image, and unique points all on the target should be included in the photographic images.

Second step, extract the image coordinate of the unique point of all camera calibration images, the automatic extraction algorithm of unique point image coordinate is referring to Zhou Fuqiang work " the gordian technique research that binocular stereo vision detects ", BJ University of Aeronautics ﹠ Astronautics's post-doctoral research work report, 2002.

On the target plane, set up world coordinate system, use o _w-x _wy _wz _wExpression, initial point is in the upper left corner, x _w, y _wAxle is parallel with the target square respectively, x _wAxle horizontal to the right, y _wThe axle straight down, z _wAxle determines that by right-hand rule world coordinate system is equivalent to the target coordinate system herein.The image coordinate of unique point is corresponding with world coordinates.

The 3rd step, utilize the image coordinate and the corresponding world coordinate of all unique points of second step extraction to come the calibration camera inner parameter, comprise video camera effective focal length, principal point and distortion factor.

According to formula [2]～[5], utilize the world coordinates X of unique point _Wi, obtain the computed image coordinate X ' of unique point _Di=[x ' _DiY ' _Di] ^T, the real image coordinate of unique point is X _Di, then have:

$f(f_x,f_y,u_0,v_0,k_1,{\mathrm{<figure-callout\; id="2"\; label="k"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">k</figure-callout>}}_2,p_1,{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20071000017300161.png"\; state="\{\{state\}\}">p</figure-callout>}}_2,R_c^w,T_c^w)={\mathrm{\&Sigma;}}_{i=1}^N{d}^2\left({X^{,}}_{\mathrm{di},}{X}_{\mathrm{di}}\right)---\left[8\right]$

Wherein N is a unique point quantity, d (X ' _Di, X _Di) represent that the calculating subpoint arrives the distance of actual subpoint.

According to formula [8], adopt the Levenberg-Marquardt nonlinear optimization method can estimate whole intrinsic parameters of the camera, comprise focal length of camera f _xAnd f _y, principal point coordinate (u ₀, v ₀), the lens distortion coefficient k ₁, k ₂, p ₁, p ₂The initial value of camera parameters is estimated referring to Zhou Fuqiang work " the gordian technique research that binocular stereo vision detects ", BJ University of Aeronautics ﹠ Astronautics's post-doctoral research work report, 2002.The Levenberg-Marquardt algorithm is referring to " Optimum Theory and method ", (Yuan Yaxiang, Sun Wenyu work, Science Press, 1999).

3, obtain the video camera external parameter R of target in the system calibration planimetric position _c ^tAnd T _c ^tConcrete steps are as follows:

The first step is placed target 10 on closet circle 7, choosing the target plane is the system calibration plane, with the vertical height L of Steel Ruler 9 measuring system calibration plane to the reference position _cTake the image of a width of cloth target with video camera, be called the system calibration image, all unique points are called the system calibration unique point on the target, and the system calibration unique point should be included in the photographic images.

Second step, the image coordinate of the unique point of extraction system calibration image, the automatic extraction algorithm of unique point image coordinate is referring to Zhou Fuqiang work " the gordian technique research that binocular stereo vision detects ", BJ University of Aeronautics ﹠ Astronautics's post-doctoral research work report, 2002.

According to formula [4] and [5], utilize its corresponding projection coordinate of real image coordinate Calculation of system calibration unique point.

On the target plane, set up the target coordinate system, use o _t-x _ty _tz _tExpression, initial point is in the upper left corner, x _t, y _tAxle is parallel with the target square respectively, x _tAxle horizontal to the right, y _tThe axle straight down, z _tAxle is determined by right-hand rule, and the projection coordinate of system calibration unique point is corresponding with the target coordinate.

The 3rd step, utilize second to go on foot the projection coordinate of the system calibration unique point of extracting and the external parameter that corresponding target coordinate is estimated video camera, comprise rotation matrix R _c ^tWith translation vector T _c ^t

Intrinsic parameters of the camera is known, according to formula [8], adopts the external parameter R that the Levenberg-Marquardt nonlinear optimization method can the direct estimation video camera _c ^tAnd T _c ^t

4, remove water-saving toilet bowl on the worktable, will the good intrinsic parameters of the camera focal length of camera f of calibration _xAnd f _y, principal point coordinate (u ₀, v ₀) and the lens distortion coefficient k ₁, k ₂, p ₁, p ₂, target is at the video camera external parameter R of system calibration planimetric position _c ^tAnd T _c ^t, calibration plane is to the vertical height L of reference position _cAnd the target coordinate of system calibration unique point is saved in the systems parameters document, calls in order to measuring phases.

After the measuring system parameter is carried out primary calibration, just can carry out continuous coverage, the concrete steps of line of ink marker linear measure longimetry are as follows:

5, the water-saving toilet bowl that will measure is placed on the worktable, uses line of ink marker drawing apparatus 25mm place under the closet circle to draw a circle line of ink marker along the closet inner wall surface, and line of ink marker width is 3～6mm.By rotating horizontal adjusting lever or moving up and down vertical supports 4, guarantee that video camera can observe all lines of ink marker.Measure the vertical range L of plane, line of ink marker place with Steel Ruler to the reference position _m, calculate the distance L=L of calibration plane to measurement plane _m-L _c

7, press the flush valve of closet, the flushing device for toilet that discharges water, treat that bath finishes after, take the image of a residual line of ink marker with video camera, be called line of ink marker measurement image.

8, calculate the physical length of the residual line of ink marker, concrete steps are:

The first step is utilized the transformation matrix H of target point and projection plane on the target coordinate Calculation measurement plane of the video camera external parameter of system calibration planimetric position and system calibration unique point.

Set up the three-dimensional measurement coordinate system, use o _m-x _my _mz _mExpression, x _m, y _mAxle is parallel to x respectively _tAnd y _tAxle, z _wAxle and z _tAxle is consistent, and initial point om is at o _t-x _ty _tz _tIn coordinate be $T_t^m=[00L{]}^T.$

According to formula [1] and [2], measurement coordinate by the target coordinate Calculation system calibration unique point correspondence of system calibration unique point, measurement coordinate by the system calibration unique point, according to formula [3], recomputate the projection coordinate of system calibration unique point, be called the new projection coordinate of system calibration unique point.The new projection coordinate of system calibration unique point is corresponding with its target coordinate.

According to formula [6] and [7], new projection coordinate and corresponding target coordinate by the system calibration unique point, calculate the transformation matrix H of projection plane to measurement plane, specific algorithm is referring to Zhou Fuqiang work " the gordian technique research that binocular stereo vision detects ", BJ University of Aeronautics ﹠ Astronautics's post-doctoral research work report, 2002.

Second step, extract the image coordinate of all residual lines of ink marker of line of ink marker measurement image, the residual line of ink marker is by forming, and the line of ink marker that all consecutive point are formed is labeled as a line of ink marker, and the non-adjacent line of ink marker is labeled as the different lines of ink marker.

Line of ink marker image coordinate extraction algorithm is divided into automatic and manual dual mode.

The automatic extraction of the line of ink marker and labeling algorithm are referring to the article " a kind of symmetrical curve structure detector " [An Unbiased Detector of Curvilinear Structures] of Carsten Steger, IEEE periodical " pattern analysis and machine intelligence ", the 20th the 2nd phase of volume, the 113rd～125 page, 1998 years.[IEEE?Transactions?on?PatternAnalysis?and?Machine?Intelligence，Vol.20，No.2，1998]。

The manual extraction of the line of ink marker adopts the mouse tracing mode, with the actual residual line of ink marker of artificial affirmation mark, the concrete operations step is: carry out and manually to choose line of ink marker order, mouse is entered the image display area of systematic survey software after, the mouse shape will be changed into " cross " from " arrow ".At the active position of the line of ink marker, press left mouse button after, unclamp mouse, and move to new active position, press mouse once more, then two of selection name a person for a particular job from being dynamically connected, after the same method, select new effective line of ink marker feature,, will finish current selection up to pressing right mouse button.When the current line of ink marker of end is selected, select the line of ink marker to show, and eject " current line of ink marker selection acknowledgement window " dialog box with green.Select " not (N) " expression, the present line of ink marker is selected incorrect, need reselect, and the step of selection as previously mentioned.If select " being (Y) ", the line of ink marker that expression is selected at present is correct, and current selected effective line of ink marker is labeled as a line of ink marker, and ejects " line of ink marker selects to finish acknowledgement window " prompted dialog frame.If select " not (N) ", then continue to select new effective line of ink marker by step noted earlier.If select " being (Y) ", then all effective lines of ink marker show that with red display manual selection of the line of ink marker finishes.

According to formula [4] and [5], by the projection coordinate of all residual lines of ink marker of real image coordinate Calculation of the line of ink marker.

In the 3rd step,,, calculate the measurement coordinate of the residual line of ink marker by the projection coordinate of the residual line of ink marker according to formula [6].

The 4th step, calculates the distance between the adjacent line of ink marker point on same the line of ink marker, and with distance with as the length of this line of ink marker, the length of calculating all residual lines of ink marker with, as final residual line of ink marker linear measure longimetry result.

9, remove water-saving toilet bowl on the worktable, preserve residual line of ink marker linear measure longimetry result.

10, repeating step 5～9, carry out new performance parameter of water-saving toilet bowl and measure.

Embodiment

" the Meter-II image pick-up card that CCD colour TV camera WAT-250D video camera, Computar T2z1816cs wide-angle lens and Canadian Matrox company produce etc. is formed the performance parameter of water-saving toilet bowl vision measurement system to the colored low-illuminance cameras 1/3 that adopts Japanese Watec company to produce.Image resolution ratio is 768 * 576 pixels, and the camera lens technical indicator is: 1/3 inch CS interface, and focusing range 1.8～3.6mm, aperture F1.6, field angle is 144.2 degree.

Adopt two dimensional surface entity target 10 as shown in Figure 2, the parameter of single camera performance parameter of water-saving toilet bowl vision system is calibrated.The square quantity of target is 10 * 10, and square is of a size of 9 * 9mm, adopts the high-resolution laser printer of 1200dpi to print and obtains.

Intrinsic parameters of the camera after the calibration is as follows:

f _x=320.769 pixels, f _y=320.899 pixels

u ₀=387.008 pixels, v ₀=316.596 pixels

k ₁＝-2.567×10 ^-1，k ₂＝5.632×10 ^-2

p ₁＝-1.838×10 ^-4，p ₂＝1.003×10 ^-3

Calibration plane to the distance of reference position is: L _c=180mm

Target is when the calibration plane position, and the external parameter of video camera is:

$R_t^c=\left[\begin{array}{ccc}9.863\&times;{10}^{-1}& 1.602\&times;{10}^{-1}& 3.962\&times;{10}^{-2}\\ -1.603\&times;{10}^{-1}& 9.870\&times;{10}^{-1}& 3.559\&times;{10}^{-4}\\ -3.905\&times;{10}^{-2}& -6.706\&times;{10}^{-3}& 9.992\&times;{10}^{-1}\end{array}\right]$

$T_t^c={\left[\begin{array}{ccc}-5.547\&times;{10}^2& -5.865\&times;{10}^2& 7.354\&times;{10}^2\end{array}\right]}^T$

In order to assess the measuring accuracy of measuring system, utilize the good measuring system of calibration, to radius is that the girth of the standard round of 70mm is measured, measurement plane distance reference position 160mm, therefore measurement plane to the distance of calibration plane is-20mm, and standard round is placed on diverse location on the measurement plane, has carried out 20 times and has measured, the RMS error that obtains is 1.8mm, has satisfied the accuracy requirement that the line of ink marker is measured.

Claims (2)

1, a kind of single camera performance parameter of water-saving toilet bowl vision measurement system is characterized in that,

1.1, it by the band wide-angle lens [2] video camera [1], adjusting mechanism, worktable [9], computing machine, image pick-up card, calibration target [10], Steel Ruler [8] and line of ink marker drawing apparatus form.Adjusting mechanism is made up of video camera fixed support [3], vertical supports [4], horizontal adjusting lever [5] and turning axle [6].Image pick-up card is installed in the calculating.Video camera is fixed on the vertical supports [4] by video camera fixed support [3].Vertical supports [4] is fixed on the horizontal adjusting lever [5], can move along horizontal adjusting lever direction, and can be around horizontal adjusting lever rotation.Laterally adjusting lever [5] is fixed on the turning axle [6], and can center on turning axle [6] rotation.Turning axle [6] is fixed on the worktable [9], and water-saving toilet bowl is placed on the worktable [9];

1.2, the upper surface of choosing video camera fixed support [3] is the reference position, and the scope of installing and measuring is the Steel Ruler [8] of 50cm on video camera fixed support [3], by screw retention, unclamps screw, Steel Ruler [8] can move up and down;

1.3, said calibration target [10] is a two dimensional surface, the unique point that sets in advance is arranged on the target, on the target plane, arrange chequered with black and white gridiron pattern, the length of side of black and white square is 5～50mm, its length of side precision is 0.01mm～0.1mm, and the publicly-owned summit of black box and white square is called lattice point.Choose that lattice point is a unique point on the target surface, unique point quantity is 16～400;

1.4, said line of ink marker drawing apparatus by slip rail [11], go up location-plate [12], location-plate [13] and soft [14] are formed down, last location-plate [12], following location-plate [13] and soft pen [14] all are screwed on slip rail [11], after unclamping screw, can move along slip rail direction, also can adjust in the horizontal direction simultaneously.When drawing the line of ink marker, actual conditions according to closet, to go up location-plate [12] and be close to the upper surface of closet circle [7], following location-plate [13] is close to the interior lower surface of closet circle [7], tighten up the screw on location-plate [12] and the following location-plate [13], adjust soft pen [14], guarantee that soft pen [11] is 25mm to the distance of last location-plate [12] along slip rail [11], move line of ink marker drawing apparatus one circle along the closet circle then, just can draw out the line of ink marker in the closet inner wall surface;

2, use performance parameter of water-saving toilet bowl vision measurement system as claimed in claim 1 to carry out the method that performance parameter of water-saving toilet bowl is measured, it is characterized in that, measuring process is divided into calibration phase and measuring phases, but carries out continuous coverage behind the primary calibration, and concrete steps are as follows:

2.1, calibration phase:

2.1.1, water-saving toilet bowl is placed on the worktable, adjust and to install video camera.Use line of ink marker drawing apparatus 25mm place under the closet circle to draw a circle line of ink marker along the closet inner wall surface, line of ink marker width is 3～6mm.By adjusting mechanism, make video camera can observe all lines of ink marker, adjust the lens focus and the aperture of video camera, guarantee that image is comparatively clear.Vertical supports [4], video camera [1] and wide-angle lens [2] are tightened up, and laterally adjusting lever [5] can rotate around turning axle [6];

2.1.2, the inner parameter of calibration camera [1].Concrete steps are as follows:

The first step, in the field range of video camera, a position is whenever moved in free, [10] at least 3 positions of non-parallel ground moving target mark, takes piece image, is called the camera calibration image, and unique points all on the target should be included in the photographic images;

Second goes on foot, and extracts the image coordinate of the unique point of all camera calibration images, and corresponding with the world coordinates of unique point;

The 3rd step, utilize the image coordinate and the corresponding world coordinate of all unique points of second step extraction to come the calibration camera inner parameter, comprise video camera effective focal length, principal point and distortion factor;

2.1.3, obtain the video camera external parameter of target in the system calibration planimetric position.Concrete steps are as follows:

The first step goes up placement target [10] at closet circle [7], and choosing the target plane is the system calibration plane, with the vertical height L of Steel Ruler [9] measuring system calibration plane to the reference position _cTake the image of a width of cloth target with video camera, be called the system calibration image, the unique point on the target is called the system calibration unique point, and all system calibration unique points should be included in the photographic images;

Second step, the image coordinate of the system calibration unique point of extraction system calibration image, according to camera model, the projection coordinate of calculated characteristics point, and corresponding with the target coordinate of unique point;

The 3rd step, utilize second to go on foot the projection coordinate of the system calibration unique point of extracting and the external parameter that corresponding target coordinate is estimated video camera, comprise rotation matrix and translation vector;

2.1.4, remove the water-saving toilet bowl on the worktable, will calibration good intrinsic parameters of the camera, target are at the video camera external parameter of system calibration planimetric position, the calibration plane vertical height L to the reference position _cThe target coordinate that reaches the system calibration unique point is saved in the systems parameters document, calls in order to measuring phases;

2.2, measuring phases:

2.2.1, the water-saving toilet bowl that will measure is placed on the worktable, uses line of ink marker drawing apparatus 25mm place under the closet circle to draw one along the closet inner wall surface and encloses the line of ink marker, line of ink marker width is 3～6mm.By rotating horizontal adjusting lever or moving up and down vertical supports [4], guarantee that video camera can observe all lines of ink marker.Measure the vertical range L of plane, line of ink marker place with Steel Ruler to the reference position _m, calculate the distance L=L of calibration plane to measurement plane _m-L _c

2.2.2, press the flush valve of closet, the flushing device for toilet that discharges water, treat that bath finishes after, take the image of a residual line of ink marker with video camera, be called line of ink marker measurement image;

2.2.3, calculate the physical length of the residual line of ink marker, concrete steps are:

The first step is utilized the conversion of target point and projection plane on the target coordinate Calculation measurement plane of the video camera external parameter of system calibration planimetric position and system calibration unique point;

Second step, extract the image coordinate of all residual lines of ink marker of line of ink marker measurement image, the residual line of ink marker is by forming, and the line of ink marker that all consecutive point are formed is labeled as a line of ink marker, and the non-adjacent line of ink marker is labeled as the different lines of ink marker.According to camera model, calculate the projection coordinate of all residual lines of ink marker;

In the 3rd step,,, calculate the measurement coordinate of the residual line of ink marker by the projection coordinate of the residual line of ink marker according to the systematic survey model;

The 4th step, calculates the distance between the adjacent line of ink marker point on same the line of ink marker, and with distance with as the length of this line of ink marker, the length of calculating all residual lines of ink marker with, as final residual line of ink marker linear measure longimetry result;

2.2.4, remove the water-saving toilet bowl on the worktable, preserve residual line of ink marker linear measure longimetry result;

2.2.5, repeating step 2.2.1～2.2.4, carry out new performance parameter of water-saving toilet bowl and measure.

Images