CN107462184A - The parameter recalibration method and its equipment of a kind of structured light three-dimensional measurement system - Google Patents

The parameter recalibration method and its equipment of a kind of structured light three-dimensional measurement system Download PDF

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CN107462184A
CN107462184A CN201710695449.8A CN201710695449A CN107462184A CN 107462184 A CN107462184 A CN 107462184A CN 201710695449 A CN201710695449 A CN 201710695449A CN 107462184 A CN107462184 A CN 107462184A
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projecting apparatus
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周平
于云雷
何思渊
蔡国超
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Southeast University
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    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G01B11/2433—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures for measuring outlines by shadow casting

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Abstract

The parameter recalibration method and its equipment of a kind of structured light three-dimensional measurement system, increase auxiliary camera in the system with a camera and a projecting apparatus to projecting apparatus intrinsic parameter progress recalibration.Place high-precision white plate, projector projects structured light patterns, original system camera and auxiliary camera collection white plate pattern.Double camera is demarcated first, obtains auxiliary camera parameter；Secondly white plate is rebuild according to principle of stereoscopic vision using the photo of shooting, on the Dian Yun back projections of reconstruction to projector are practised physiognomy again, calculate corresponding projected phase, and make the difference to obtain phase residual error value with its actual phase, the error amount of projecting apparatus transverse direction equivalent focal length and horizontal photocentre is finally calculated using the principle of least square, the recalibration of projecting apparatus intrinsic parameter is completed, improves the stated accuracy of structured light three-dimensional measurement system.

Description

The parameter recalibration method and its equipment of a kind of structured light three-dimensional measurement system
Technical field
The present invention relates to a kind of projecting apparatus intrinsic parameter recalibration method in structured light three-dimensional measurement system and its equipment, category In technical field of computer vision.
Background technology
Structured light three-dimensional measurement system is a kind of important three-dimension measuring system in computer vision field, have it is quick, Assemble simple, high-precision feature.And the precision of systematic parameter then directly determines the measurement accuracy of system.
The parameter of structured light three-dimensional measurement system is obtained by demarcating, and the quality of scaling method, which directly determines, to be obtained Systematic parameter precision.The demarcation of system at present mainly includes two parts, respectively camera calibration and projector calibrating.Phase The research of machine demarcation is long-standing, and classical method has Method of Direct Liner Transformation, Tsai two-stage calibration method, Zhang Zhengyou plane Standardization and self-calibrating method etc..It is the most commonly used and ripe with Zhang Zhengyou plane reference method at present, form different languages Say tool box.Projector calibrating is completed based on the scaling method of camera, and it is different that different researchers are that projecting apparatus establishes Mathematical modeling simultaneously gives corresponding scaling method, wherein it is more conventional it is a kind of be that projecting apparatus is considered as a reverse phase Machine, projecting apparatus " is shot " photo by the method for structure light, then projecting apparatus is demarcated.The mark of projecting apparatus at present Fixed still immature, the proj ector parameters error that the above method is obtained is often the several times of camera parameter error, and this is also current Structured light three-dimensional measurement system, the measurement accuracy for the measuring system being particularly made up of a camera and a projecting apparatus be not high Main cause.
The content of the invention
The problem of existing for existing projector calibrating technology, the present invention proposes a kind of structured light three-dimensional measurement system The recalibration method and apparatus of middle projecting apparatus intrinsic parameter, technical scheme are as follows：
A kind of parameter recalibration method of structured light three-dimensional measurement system, structured light three-dimensional measurement system include a camera With a projecting apparatus, it is characterised in that：The proj ector parameters in structured light three-dimensional measurement system are demarcated for the first time first, so An auxiliary camera is set up in structured light three-dimensional measurement system afterwards, based on to intrinsic parameter in the first calibration process of proj ector parameters The analysis of error, parameter error is attributed to the error of horizontal principal point and horizontal equivalent focal length in projecting apparatus intrinsic parameter, then divided The specific influence of horizontal principal point and horizontal equivalent focal length both intrinsic parameter errors for system is separated out, is marked again by auxiliary camera The intrinsic parameter of projecting apparatus is determined, to improve the stated accuracy of structured light three-dimensional measurement system；Comprise the following steps：
1) camera and projecting apparatus are built into structured light three-dimensional measurement system, just deutero-albumose is carried out to the parameter of projecting apparatus Fixed, projecting apparatus is that scaling board projects one group of grating to testee, using phase measuring profilometer method, is obtained through testee I.e. scaling board case depth modulation phase, accordingly direct reverse obtain world coordinates：
Wherein, fcx,fcy,fpxRepresent respectively the horizontal equivalent focal length of camera, longitudinal equivalent focal length and projecting apparatus laterally etc. Imitate focal length；cccx,cccy,ccpxThe horizontal principal point of the horizontal principal point of camera, longitudinal principal point and projecting apparatus is represented respectively；Xw,Yw,Zw Represent coordinate value of the certain point under world coordinate system in space；Due to fpxWith ccpxRespectively include error delta f and Δ cc, Δ F=fT-fpx,fTFor fpxTrue value, Δ cc=ccT-ccpx, ccTFor ccpxTrue value, therefore the weight obtained by formula (1)~(3) Cloud of laying foundations also includes error；R in formula (1)~(3)i,mj,tkBy Rc,Tc,Rp,TpObtain, wherein ri=r1~r9, mj=m1 ~m9, tk=t1~t6, Rc,TcRepresent the spin matrix and translation vector of camera, Rp,TpRepresent the spin matrix peace of projecting apparatus The amount of shifting to, concrete form are as follows：
2) auxiliary camera, the position of setting are set up in the structured light three-dimensional measurement system that a camera and projecting apparatus are formed Basic demand is that auxiliary camera photographs scaling board simultaneously with original camera, and scaling board is placed in into auxiliary camera and original camera In tested region, combined calibrating is carried out to the dual camera systems being made up of auxiliary camera and former camera, obtains the interior of auxiliary camera Outer parameter matrix between parameter matrix and two cameras；
3) scaling board is measured and rebuild, start projector projects grating pattern, two cameras gather demarcation respectively Plate image, based on principle of stereoscopic vision, scaling board is carried out using the image of two cameras to rebuild acquisition three dimensional point cloud PA；
4) the three dimensional point cloud PA of acquisition is calculated according to projection equation and projected in the projection plane of projecting apparatus, obtained uFAnd Xn, wherein uFThe row coordinate projected to for the proj ector parameters of the included errors of three dimensional point cloud PA after projection plane, Xn Normalization projector coordinates are represented, are defined as Xn=(Xp/Zp)；According further to projector projects pattern phase and projection plane One-to-one relationship directly obtains up, upFor the row coordinate of the projector projects plane directly calculated by phase, consider to sit in the world An arbitrfary point C in given space under mark systemw, remember Cw=[Xw Yw Zw] represent coordinate of this under world coordinate system, then its Corresponding point C in projector coordinates systempCoordinate be just denoted as Cw=[Xp Yp Zp]；Projection equation is as follows：
Cp=RpCw+Tp (4)
It is hereby achieved that：
uF=fpxXn+ccpx (6)
up=(fpx+Δf)Xn+ccpx+Δcc (7)
Because projecting apparatus intrinsic parameter includes error, therefore the projection row coordinate u of gainedFWith error, and upPass through phase Directly it is calculated, not comprising projecting apparatus intrinsic parameter error, re-projection row coordinate u is calculatedFWith true row coordinate up, counterweight Project row coordinate uFWith true row coordinate upMake the difference, obtain phase residual error；
5) institute in the three dimensional point cloud PA of acquisition is a little handled according to step 4) is described, obtained by row coordinate uFWith upThe residual error set of composition, u can be directly obtained from phasep, u is obtained further according to a cloud PA re-projectionFAnd XnAfterwards using most A young waiter in a wineshop or an inn multiplies principle and obtains the error amount of the corrected value of projecting apparatus intrinsic parameter, i.e., horizontal equivalent focal length correction value delta f and horizontal photocentre Δ cc, according to the derivation in step 4), obtain following formula
up-uF=(Δ f) Xn+(Δcc) (8)
6) projecting apparatus intrinsic parameter is directly corrected according to correction value delta f and Δ cc, that is, obtains the mark again of projecting apparatus intrinsic parameter Definite value.
Equipment used in the parameter recalibration method of said structure light three-dimension measuring system, is characterised by：Including white Scaling board, two industrial cameras, a Digital light projector, a computer and data transmission link and control circuit, will One camera and projecting apparatus point or so are fixed on support, and camera is hit exactly in support one end, projecting apparatus in support, adjusts optical axis Angle less parallel, structured light three-dimensional measurement system is formed, then this structured light three-dimensional measurement system is demarcated for the first time, just After the completion of secondary demarcation, another auxiliary camera is placed in the support other end, adjusts the camera focus, focused to tested plane, two Platform camera and projecting apparatus are connected by data transmission link and control circuit with computer, and it is unglazed that whole system is placed in into one In darkroom, white calibration plate is placed in focal distance front and back position on projector projects direction, projected image is clearly shown In tested flat area, two phase functions photograph demarcation plate pattern simultaneously, start computer-controlled program control projecting apparatus to Scaling board projects digital raster image, and gathers the lithograph picture after being projected in real time by the camera of left and right two, completes collection Afterwards, the image of collection is handled according to recalibration method, by be calculated projecting apparatus intrinsic parameter recalibration result and Systematic parameter after recalibration.
Advantages of the present invention and remarkable result：Stated accuracy is evaluated by the way of re-projection at present, but in projecting apparatus The calibrated error of parameter has no idea to find by re-projection, therefore is difficult to the stated accuracy for further improving projecting apparatus intrinsic parameter. The present invention increases auxiliary camera in the system with a camera and a projecting apparatus and carries out recalibration to projecting apparatus intrinsic parameter. Place high-precision white plate, projector projects structured light patterns, original system camera and auxiliary camera collection white plate figure Case.Double camera is demarcated first, obtains auxiliary camera parameter；Secondly using the photo of shooting according to principle of stereoscopic vision weight Build white plate, the Dian Yun back projections of reconstruction to projector are practised physiognomy again on, calculate corresponding projected phase, and with Its actual phase makes the difference to obtain phase residual error value, finally using the principle of least square be calculated projecting apparatus transverse direction equivalent focal length and The error amount of horizontal photocentre, the projecting apparatus intrinsic parameter of structured light three-dimensional measurement system is corrected, completes projecting apparatus intrinsic parameter Recalibration, further improve its three-dimensional stated accuracy or even measurement accuracy.System reconstructing result and recalibration after recalibration Before compared to having clear improvement, its absolute spatial position and relative accuracy are all improved.
Brief description of the drawings
Fig. 1 is impact analysis of the horizontal principal point error for system；
Fig. 2 is the influence result signal of horizontal principal point error；
Fig. 3 is impact analysis of the horizontal equivalent focal length error for system；
Fig. 4 is the influence result signal of horizontal equivalent focal length error pair；
Fig. 5 is to use equipment structure chart used in the inventive method.
Embodiment
A kind of projecting apparatus intrinsic parameter recalibration method of structured light three-dimensional measurement system of the present invention, specific to one The measuring system of camera and a projecting apparatus, improve system calibrating precision.Specifically increase auxiliary camera on original system, place High-precision white plate (scaling board), projector projects structured light patterns, original system camera and auxiliary camera collection white are flat Plate pattern.Double camera is demarcated first, obtains auxiliary camera parameter；Secondly it is former according to stereoscopic vision using the photo of shooting Reason rebuilds white plate, the Dian Yun back projections of reconstruction to projector are practised physiognomy again on, calculate corresponding projected phase, And make the difference to obtain phase residual error value with its actual phase；Projecting apparatus laterally equivalent Jiao finally is calculated using the principle of least square Away from the error amount with horizontal photocentre, the recalibration of completion projecting apparatus intrinsic parameter, the demarcation for improving structured light three-dimensional measurement system is smart Degree.
If the horizontal principal point in projecting apparatus intrinsic parameter is ccpx, true value ccT, influence of its error for system such as Fig. 1 institutes Show.MlMrRepresent in space 2 points on physical plane of line, Ml'Mr' represent the M after three-dimensional reconstructionlMr.Each coordinate in Fig. 1 System is defined as follows：Ow:{Xw Yw ZwRepresent world coordinate system, corresponding [Xw Yw Zw] certain point is represented in space in world coordinates Coordinate value under system；Define Op:{Xp Yp ZpRepresent projector coordinates system, corresponding [Xp Yp Zp] represent certain point in space and exist Coordinate value under projector coordinates system；Define Oc:{Xc Yc ZcRepresent camera coordinates system, corresponding [Xc Yc Zc] represent in space Coordinate value of the certain point under camera coordinates system；Define { uc vcRepresent the pixel coordinate system of camera imaging front, corresponding ucWith vcThe row coordinate and row coordinate of certain point on camera imaging front are represented respectively, and unit is pixel；Define { up vpRepresent projection Instrument projects the pixel coordinate system of front, corresponding upWith vpThe row coordinate and row for representing certain point on projector projects front respectively are sat Mark, unit is pixel.Remember horizontal principal point ccpxComprising error be Δ cc, can be expressed as
Δ cc=ccT-ccpx
As seen from Figure 1, actual object MlMrError be more than the translation of position, but including certain rotation and Deformation.Point cloud area after reconstruction is slightly larger than original objects, and not parallel with original objects.This means the point cloud after reconstruction is deposited In certain linear deformation, and error can't be reacted directly into the result of re-projection as caused by principal point offset.Fig. 1 institutes Corresponding plane emulation signal is as shown in Figure 2.
If the horizontal equivalent focal length in projecting apparatus intrinsic parameter is fpx, true value fT, influence of its error for system such as Fig. 3 It is shown.As can be seen that the error of horizontal equivalent focal length can't cause the obvious inclined of a cloud position as horizontal principal point error Difference.Point cloud after reconstruction is equipped with a kind of " tendency " of rotation compared to raw bits, and rotary middle point is denoted as M.And it can be seen that rotation During turning, point M does not have the skew for producing position.Remember fpxError be Δ f, can be expressed as：
Δ f=fT-fpx
Wherein fTIt is the true value after correction, for example, in figure 3, Δ f ＜ 0.Plane emulation signal such as Fig. 4 corresponding to Fig. 3 It is shown.
Structured-light system is typically made up of a projecting apparatus and a camera, and its specific three-dimensional measurement scheme is as follows：
Projecting apparatus to testee project one group of grating, using the certain methods in phase measuring profilometer can obtain through The phase that object surface depth is modulated, accordingly can directly reverse obtain world coordinates.Formula is as follows：
Wherein fcx,fcy,fpxThe transverse direction of the horizontal equivalent focal length of camera, longitudinal equivalent focal length and projecting apparatus is represented respectively Equivalent focal length.cccx,cccy,ccpxThe horizontal principal point of the horizontal principal point of camera, longitudinal principal point and projecting apparatus, X are represented respectivelyw, Yw,ZwRepresent coordinate value of the certain point under world coordinate system in space.Due to fpxWith ccpxError is included, therefore by above formula Obtained reconstruction point cloud also includes error.ri,mj,tkBy Rc,Tc,Rp,TpObtain, wherein ri=r1~r9, mj=m1~m9, tk= t1~t6, Rc,TcRepresent the spin matrix and translation vector of camera, Rp,TpRepresent the spin matrix and translation vector of projecting apparatus.It is fixed Justice is as follows：
Said system parameter can be obtained by the first demarcation to systematic parameter.
The bearing calibration of projecting apparatus intrinsic parameter is specific as follows：
It is assumed that an arbitrfary point C in space is given under world coordinate systemw, remember Cw=[Xw Yw Zw] represent that the point is sat in the world The coordinate under system is marked, then its corresponding point C in projector coordinates systempCoordinate be denoted as Cp=[Xp Yp Zp].Projection equation is such as Under：
Cp=RpCw+Tp (4)
In practice, it is necessary to use normalized projector coordinates, X is defined asn=(Xp/Zp)。
Further assume that uFObtained for projection, contain intrinsic parameter error；And upDirectly it is calculated for phase, not comprising interior Parameter error.It can then obtain：
uF=fpxXn+ccpx (6)
up=(fpx+Δf)Xn+ccpx+Δcc (7)
It is possible thereby to export
up-uF=(Δ f) Xn+(Δcc) (8)
It can be seen from the three-dimensional reconstruction formula of structure light, u can be directly obtained from phasep, further according to the throwing again of true point cloud Shadow obtains uFAnd XnAfterwards, you can correction value delta f and Δ cc are obtained according to the principle of least square.
Such as Fig. 5, equipment used in the parameter recalibration method of structured light three-dimensional measurement system includes white calibration plate, two Platform industrial camera, a Digital light projector, a computer and data transmission link and control circuit, by a camera and Projecting apparatus point or so is fixed on support, and camera is hit exactly in support one end, projecting apparatus in support, forms structural light three-dimensional measurement System, then this structured light three-dimensional measurement system is demarcated for the first time, after the completion of first demarcation, another auxiliary camera put In the support other end, the camera focus is adjusted, focuses and passes through data transmission link to tested plane, two cameras and projecting apparatus It is connected with control circuit with computer, whole system is placed in a unglazed darkroom, white calibration plate is placed in into projecting apparatus throws Focal distance front and back position on direction is penetrated, projected image is clearly shown in tested flat area, one is placed after master plate Open and photograph demarcation plate pattern simultaneously with black dossal, two phase functions, start computer-controlled program and control projecting apparatus to mark Fixed board projects digital raster image, and gathers the lithograph picture after being projected in real time by the camera of left and right two, after completing collection, The image of collection is input in supporting computer program, by the recalibration result and again that projecting apparatus intrinsic parameter is calculated Calibrated systematic parameter.
1) as shown in figure 5, building the structured light three-dimensional measurement system being made up of a camera and a projecting apparatus first, and System is demarcated.
2) as shown in figure 5, increasing auxiliary camera in original system structure, and one piece of high-precision white plate is placed in tested In region, adjustment auxiliary camera is focused to focal plane.
3) auxiliary camera is demarcated, and on the basis of original structure light three-dimension measuring system, dual camera systems carried out Combined calibrating.
4) projector projects grating pattern is started, two cameras gather flat board pattern in real time simultaneously respectively.
5) photo collected according to two cameras, point cloud registering and three-dimensional reconstruction are carried out according to principle of stereoscopic vision, Obtain the three-dimensional point cloud of white plate.
7) three-dimensional point cloud of acquisition is projected on the plane of departure of projecting apparatus according to proj ector parameters, i.e., according to the cloud Re-projection obtain uFAnd Xn.U is obtained according further to phase calculationp, to uFAnd upMake the difference, obtain phase residual error.
8) according to phase residual error, using the principle of least square, the corrected value of projecting apparatus intrinsic parameter is calculated, completes system The recalibration of parameter.

Claims (2)

1. a kind of parameter recalibration method of structured light three-dimensional measurement system, structured light three-dimensional measurement system include a camera and One projecting apparatus, it is characterised in that：The proj ector parameters in structured light three-dimensional measurement system are demarcated for the first time first, then An auxiliary camera is set up in structured light three-dimensional measurement system, based on being missed to intrinsic parameter in the first calibration process of proj ector parameters The analysis of difference, parameter error is attributed to the error of horizontal principal point and horizontal equivalent focal length in projecting apparatus intrinsic parameter, and post analysis Go out the specific influence of horizontal principal point and horizontal equivalent focal length both intrinsic parameter errors for system, by auxiliary camera recalibration The intrinsic parameter of projecting apparatus, to improve the stated accuracy of structured light three-dimensional measurement system；Comprise the following steps：
1) camera and projecting apparatus are built into structured light three-dimensional measurement system, the parameter of projecting apparatus are demarcated for the first time, Projecting apparatus is that scaling board projects one group of grating to testee, using phase measuring profilometer method, is obtained through testee i.e. Scaling board case depth modulation phase, accordingly direct reverse obtain world coordinates：
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Wherein, fcx,fcy,fpxHorizontal equivalent focal length, equivalent Jiao of the transverse direction of longitudinal equivalent focal length and projecting apparatus of camera are represented respectively Away from；cccx,cccy,ccpxThe horizontal principal point of the horizontal principal point of camera, longitudinal principal point and projecting apparatus is represented respectively；Xw,Yw,ZwRepresent Coordinate value of the certain point under world coordinate system in space；Due to fpxWith ccpxRespectively include error delta f and Δ cc, Δ f= fT-fpx,fTFor fpxTrue value, Δ cc=ccT-ccpx, ccTFor ccpxTrue value, therefore the reconstruction obtained by formula (1)~(3) Point cloud also includes error；R in formula (1)~(3)i,mj,tkBy Rc,Tc,Rp,TpObtain, wherein ri=r1~r9, mj=m1~ m9, tk=t1~t6, Rc,TcRepresent the spin matrix and translation vector of camera, Rp,TpRepresent spin matrix and the translation of projecting apparatus Vector, concrete form are as follows：
<mfenced open = "" close = ""> <mtable> <mtr> <mtd> <mrow> <msub> <mi>R</mi> <mi>c</mi> </msub> <mo>=</mo> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <msub> <mi>r</mi> <mn>1</mn> </msub> </mtd> <mtd> <msub> <mi>r</mi> <mn>2</mn> </msub> </mtd> <mtd> <msub> <mi>r</mi> <mn>3</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>r</mi> <mn>4</mn> </msub> </mtd> <mtd> <msub> <mi>r</mi> <mn>5</mn> </msub> </mtd> <mtd> <msub> <mi>r</mi> <mn>6</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>r</mi> <mn>7</mn> </msub> </mtd> <mtd> <msub> <mi>r</mi> <mn>8</mn> </msub> </mtd> <mtd> <msub> <mi>r</mi> <mn>9</mn> </msub> </mtd> </mtr> </mtable> </mfenced> </mrow> </mtd> <mtd> <mrow> <mi>a</mi> <mi>n</mi> <mi>d</mi> </mrow> </mtd> <mtd> <mrow> <msub> <mi>T</mi> <mi>c</mi> </msub> <mo>=</mo> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <msub> <mi>t</mi> <mn>1</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>t</mi> <mn>2</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>t</mi> <mn>3</mn> </msub> </mtd> </mtr> </mtable> </mfenced> </mrow> </mtd> </mtr> </mtable> </mfenced>
<mfenced open = "" close = ""> <mtable> <mtr> <mtd> <mrow> <msub> <mi>R</mi> <mi>p</mi> </msub> <mo>=</mo> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <msub> <mi>m</mi> <mn>1</mn> </msub> </mtd> <mtd> <msub> <mi>m</mi> <mn>2</mn> </msub> </mtd> <mtd> <msub> <mi>m</mi> <mn>3</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>m</mi> <mn>4</mn> </msub> </mtd> <mtd> <msub> <mi>m</mi> <mn>5</mn> </msub> </mtd> <mtd> <msub> <mi>m</mi> <mn>6</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>m</mi> <mn>7</mn> </msub> </mtd> <mtd> <msub> <mi>m</mi> <mn>8</mn> </msub> </mtd> <mtd> <msub> <mi>m</mi> <mn>9</mn> </msub> </mtd> </mtr> </mtable> </mfenced> </mrow> </mtd> <mtd> <mrow> <mi>a</mi> <mi>n</mi> <mi>d</mi> </mrow> </mtd> <mtd> <mrow> <msub> <mi>T</mi> <mi>p</mi> </msub> <mo>=</mo> <mfenced open = "[" close = "]"> <mtable> <mtr> <mtd> <msub> <mi>t</mi> <mn>4</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>t</mi> <mn>5</mn> </msub> </mtd> </mtr> <mtr> <mtd> <msub> <mi>t</mi> <mn>6</mn> </msub> </mtd> </mtr> </mtable> </mfenced> </mrow> </mtd> </mtr> </mtable> </mfenced>
2) auxiliary camera is set up in the structured light three-dimensional measurement system that a camera and projecting apparatus are formed, the position of setting is basic It is required that photograph scaling board simultaneously for auxiliary camera and original camera, scaling board is placed in the tested of auxiliary camera and original camera In region, combined calibrating is carried out to the dual camera systems being made up of auxiliary camera and former camera, obtains the intrinsic parameter of auxiliary camera Outer parameter matrix between matrix and two cameras；
3) scaling board is measured and rebuild, start projector projects grating pattern, two cameras gather scaling board figure respectively Picture, based on principle of stereoscopic vision, scaling board is carried out using the image of two cameras to rebuild acquisition three dimensional point cloud PA；
4) the three dimensional point cloud PA of acquisition is calculated according to projection equation and projected in the projection plane of projecting apparatus, obtain uFWith Xn, wherein uFThe row coordinate projected to for the proj ector parameters of the included errors of three dimensional point cloud PA after projection plane, XnRepresent Projector coordinates are normalized, are defined as Xn=(Xp/Zp)；According further to projector projects pattern phase and projection plane one by one Corresponding relation directly obtains up, upFor the row coordinate of the projector projects plane directly calculated by phase, consider in world coordinate system An arbitrfary point C in given space downw, remember Cw=[Xw Yw Zw] representing coordinate of this under world coordinate system, then it is being projected Corresponding point C in instrument coordinate systempCoordinate be just denoted as Cp=[Xp Yp Zp]；Projection equation is as follows：
Cp=RpCw+Tp (4)
It is hereby achieved that：
<mrow> <msub> <mi>X</mi> <mi>n</mi> </msub> <mo>=</mo> <mfrac> <msub> <mi>X</mi> <mi>p</mi> </msub> <msub> <mi>Z</mi> <mi>p</mi> </msub> </mfrac> <mo>=</mo> <mfrac> <mrow> <msub> <mi>m</mi> <mn>1</mn> </msub> <msub> <mi>X</mi> <mi>w</mi> </msub> <mo>+</mo> <msub> <mi>m</mi> <mn>2</mn> </msub> <msub> <mi>Y</mi> <mi>w</mi> </msub> <mo>+</mo> <msub> <mi>m</mi> <mn>3</mn> </msub> <msub> <mi>Z</mi> <mi>w</mi> </msub> <mo>+</mo> <msub> <mi>t</mi> <mn>4</mn> </msub> </mrow> <mrow> <msub> <mi>m</mi> <mn>7</mn> </msub> <msub> <mi>X</mi> <mi>w</mi> </msub> <mo>+</mo> <msub> <mi>m</mi> <mn>8</mn> </msub> <msub> <mi>Y</mi> <mi>w</mi> </msub> <mo>+</mo> <msub> <mi>m</mi> <mn>9</mn> </msub> <msub> <mi>Z</mi> <mi>w</mi> </msub> <mo>+</mo> <msub> <mi>t</mi> <mn>6</mn> </msub> </mrow> </mfrac> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>5</mn> <mo>)</mo> </mrow> </mrow>
uF=fpxXn+ccpx (6)
up=(fpx+Δf)Xn+ccpx+Δcc (7)
Because projecting apparatus intrinsic parameter includes error, therefore the projection row coordinate u of gainedFWith error, and upIt is direct by phase It is calculated, not comprising projecting apparatus intrinsic parameter error, re-projection row coordinate u is calculatedFWith true row coordinate up, to re-projection Row coordinate uFWith true row coordinate upMake the difference, obtain phase residual error；
5) institute in the three dimensional point cloud PA of acquisition is a little handled according to step 4) is described, obtained by row coordinate uFWith upThe residual error set of composition, u can be directly obtained from phasep, u is obtained further according to a cloud PA re-projectionFAnd XnA most young waiter in a wineshop or an inn is utilized afterwards Multiply principle and obtain the error amount Δ cc of the corrected value of projecting apparatus intrinsic parameter, i.e., horizontal equivalent focal length correction value delta f and horizontal photocentre, According to the derivation in step 4), following formula is obtained
up-uF=(Δ f) Xn+(Δcc) (8)
6) projecting apparatus intrinsic parameter is directly corrected according to correction value delta f and Δ cc, that is, obtains the recalibration value of projecting apparatus intrinsic parameter.
2. equipment used in the parameter recalibration method of structured light three-dimensional measurement system according to claim 1, feature It is：Including white calibration plate, two industrial cameras, a Digital light projector, a computer and data transmission link And control circuit, a camera and projecting apparatus point or so are fixed on support, by camera in support one end, projecting apparatus is in support Center, optical axis angle less parallel is adjusted, form structured light three-dimensional measurement system, then this structured light three-dimensional measurement system is entered The first demarcation of row, after the completion of first demarcation, is placed in the support other end by another auxiliary camera, adjusts the camera focus, focus To tested plane, two cameras and projecting apparatus are connected by data transmission link and control circuit with computer, will be entirely System is placed in a unglazed darkroom, and white calibration plate is placed in into focal distance front and back position on projector projects direction, makes projection Image can clearly be shown in tested flat area, and two phase functions photograph demarcation plate pattern simultaneously, start computer control journey Sequence controls projecting apparatus to project digital raster image to scaling board, and gathers the flat board after being projected in real time by the camera of left and right two Image, after completing collection, the image of collection is handled according to recalibration method, by the way that projecting apparatus intrinsic parameter is calculated Systematic parameter after recalibration result and recalibration.
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