JP3536097B2  Method and apparatus for measuring grating projection shape using frequency modulation grating  Google Patents
Method and apparatus for measuring grating projection shape using frequency modulation gratingInfo
 Publication number
 JP3536097B2 JP3536097B2 JP2002057776A JP2002057776A JP3536097B2 JP 3536097 B2 JP3536097 B2 JP 3536097B2 JP 2002057776 A JP2002057776 A JP 2002057776A JP 2002057776 A JP2002057776 A JP 2002057776A JP 3536097 B2 JP3536097 B2 JP 3536097B2
 Authority
 JP
 Japan
 Prior art keywords
 phase
 frequency
 distribution
 θ
 grating
 Prior art date
 Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
 Active
Links
 230000000051 modifying Effects 0.000 title claims description 23
 230000000875 corresponding Effects 0.000 claims 2
 238000004364 calculation methods Methods 0.000 description 4
 235000019571 color Nutrition 0.000 description 3
 238000004519 manufacturing process Methods 0.000 description 1
 239000000203 mixtures Substances 0.000 description 1
Description
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring method and apparatus, and more particularly to a method and apparatus for measuring shape from an image of an object on which a grid is projected.
[0002]
2. Description of the Related Art In a conventional shape measuring method, a phase distribution obtained by phase analysis of a lattice has a discontinuous value of 0 to 2π, and in order to obtain a unique value for a position, a resolution is required. It was necessary to drop the grating to project a grating with a large pitch, or to make the phase distribution of the grating continuous (phase connection). By making the phase distribution of the grating continuous, the phase value and the height of the object can be associated onetoone, and the height of the object can be estimated from the phase value. In the conventional phase connection method, the height cannot be obtained when the object has a sharp step by using only one type of grating. In order to overcome this drawback, there is a method of using a plurality of grids having different pitches, but it has a drawback that the structure of the measuring device becomes complicated and it is not suitable for continuous analysis.
As a method of making the phase distribution of the grating continuous,
Yoshiharu Morimoto, Yasuyuki Seguchi, Toshihiko Azuma, "Strain Analysis by Moire Method Using Fourier Transform," Proceedings of the Japan Society of Mechanical Engineers, 54 (24), 15461552, (19).
98), there is a method of referring to the phase values of surrounding pixels. In this method, the phase values of two adjacent pixels are compared, and the point where a sudden change is judged to be a phase change is made continuous, but it is susceptible to noise, and the shape of an object with a sharp step is changed. Has the drawback that it cannot measure.
On the other hand, “Shape measurement using an active liquid crystal light source” by Satoshi Kakuuchi, Kunihiro Nakamoto, Toru Sakamoto and Koichi Iwata is a method that is not easily affected by noise and can perform phase connection accurately even when there is a sharp step. , Proceedings of the Japan Society of Mechanical Engineers, 54 (2
4), pp. 15461552 (1995), there is a method of using a plurality of gratings having different pitches. Since this method performs phase connection for each pixel while referencing a plurality of phase distributions having different pitches from each other, it is not affected by surrounding pixels, but a plurality of gratings must be projected. Becomes complicated. The inventors of the present invention, in Japanese Patent Application No. 2000279457, entitled "Realtime Shape Deformation Measuring Method by Color Rectangular Wave Grating Projection", simultaneously project two types of gratings having different pitches using a color film, and perform color separation after photographing. So I disclosed a method to perform phase connection in real time, but a special camera is required,
It has the drawback that it is difficult to measure dark objects. Further, the inventors of the present invention, in Japanese Patent Application No. 2001315178 "Shape Measuring Method and Shape Measuring Device Using Monochromatic Rectangular Wave Grating", use a gray grating that combines two kinds of rectangular waves with different pitches in real time. However, there is a drawback that the contrast of the grating is deteriorated in addition to the necessity of photographing at least 12 times.
[0004]
SUMMARY OF THE INVENTION In view of the above,
An object of the present invention is to provide a shape measuring method and device capable of performing phase connection with a device having a simple structure.
[0005]
According to a first aspect of the present invention, in a shape measuring method for obtaining a height distribution of an object, a frequency modulation grating in which frequency and luminance are cyclically changed depending on a position is provided. A step of projecting onto the measurement target object while moving at a speed; a step of continuously photographing the measurement target object onto which the grating is projected; a phase distribution relating to frequency and luminance relating to luminance from the photographed image; A step of obtaining a phase distribution, a step of phaseconnecting using the phase distribution regarding the frequency, and a phase distribution regarding luminance, and a step of making the phaseconnected phase distribution correspond to the height distribution of the measurement target object. It is characterized by including and.
According to a second aspect of the present invention, in the shape measuring method according to the first aspect, the frequency modulation grating is at coordinates (x, y) in the image of the measurement target object onto which the frequency modulation grating is projected. The luminance I is A, the amplitude of the frequency change, θ _{1} (x, y) is the initial phase of the phase change component, and θ _{2}
(X, y) is the initial phase of the frequency change component, α is the lattice shift
When the moving distance , P _{1} is the period of the phase change component, and P _{2} is the period of the frequency change component, the following equation (1) is used.
[Equation 2]
According to a third aspect of the present invention, in a shape measuring apparatus for obtaining a height distribution of an object, a grating slide having an image of a frequency modulation grating in which frequency and luminance are cyclically changed depending on a position, and Moving means for moving the lattice slide at a predetermined speed, projection means for projecting the image of the lattice of the lattice slide on the measurement target object, and photographing for continuously capturing the measurement target object on which the grid is projected at constant intervals. Means, means for respectively obtaining a phase distribution regarding frequency and a phase distribution regarding luminance from the captured image, means for performing phase connection using the phase distribution regarding the frequency and the phase distribution regarding luminance, and And a means for associating the phase distribution connected in phase with the height distribution of the object to be measured.
[0008]
According to the first aspect of the present invention, a grid pattern (hereinafter referred to as a frequency modulation grid) in which the pitch periodically changes depending on the position is projected on the object, and the surface shape is noncontact, high speed, and high accuracy. measure. In the frequency modulation grating, two types of components, a brightness change component and a frequency change component, are incorporated in a monochromatic grating. Analyzing the phase distribution of these two components,
By performing phase connection, it is possible to accurately measure the shape of an object having a large step or a discontinuous shape. Also, 1
Since the grids of various types are projected by shifting at regular intervals,
It can be realized with a device having a simple structure.
According to the second aspect of the present invention, the frequency modulated wave grating incorporating the two kinds of components of the luminance change component and the frequency change component can be realized by making the equation (1) hold.
[0010]
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a general configuration for executing the shape measuring method according to the present invention. In this example, the shape of the object 10 is measured. A reference grating slide 1 on which a frequency modulation grating is printed is attached to a moving table 2, and the moving table 2 can be finely moved in the xaxis direction by a stepping motor 3 under the control of a controller 6. A projection lens 5 is arranged on the front surface of the reference grid slide 1, and a light source 4 is arranged on the back surface thereof so that the grid is projected onto the measurement object 10. The light source 4 faces the object 10 to be measured, and the projection lens 5 and the surface of the reference grating slide 1 are parallel to each other. CC
The D camera 8 photographs the measurement target object on which the lattice is projected, and supplies the photographed lattice image to the phase calculation computer 7. The phase calculation computer 7 is a controller 6
In accordance with the instruction, the phase difference distribution output image is obtained from the lattice image taken by the CCD camera 8 while moving the reference lattice slide 1, and is supplied to the display device 9. The display device 9 displays the phase difference distribution output image.
The shape measuring method according to the present invention using the above configuration will be described below. 1 pixel (x,
The luminance I of the frequency modulation grating photographed in y) is expressed by the following equation.
[Equation 3] In Expression (1), α represents the moving distance of the lattice. Also,
θ _{1} (x, y) is the initial phase of the phase change component, θ _{2} (x, y
y) is the initial phase of the frequency change component, and A represents the amplitude of the frequency change. P _{1} and P _{2} are the periods of the phase change component and the frequency change component, respectively, and in the case of the present embodiment,
P _{1} : P _{2} = 3: 3n + 1 (n is a natural number) is satisfied. a and b represent a brightness amplitude (contrast) component and a bias component, respectively. The underlined portion shows the frequency change component. The luminance I when the shot nine times by changing each P _{2/3} α I _{0.} ． ． I _{8}
[Equation 4] Becomes I obtained when P _{1} : P _{2} = 3: 22
Images of _{0 to} I _{8} are shown in FIGS. 2 (a) to 2 (i), respectively.
Here, the following expression is established from P _{1} : P _{2} = 3: 3n + 1.
[Equation 5] Therefore, I _{0 to} I _{8} in the equation (2) can be rewritten as follows.
[Equation 6] Focusing on the luminances I _{0} , I _{3} , and I _{6} , they have the same frequency change component, and each phase change component is 2π /.
You can see that they differ by 3. Therefore, by applying the phase shift method, the initial phase of the grating including the frequency change component can be obtained. If the initial phase including this frequency change component is defined as Θ _{0} , Θ _{0} is expressed by the following equation.
[Equation 7] However, in Expression (5), arg is an operator for phase calculation, and the definition is shown in the following table. definition of arg (x, y)
[Table 1] The same applies to I _{1} , I _{4} , I _{7,} and I _{2} , I _{5} , I _{8} , and Θ _{1} and Θ _{2} are defined as shown in the following equations.
[Equation 8]
[Equation 9] Images of Θ _{0} , Θ _{1} , and Θ _{2} thus obtained are shown in FIGS. 3a, 3b, and 3c, respectively. Furthermore, equation (5)
Using (7), the initial phase θ _{2} of the frequency change component can be calculated as follows.
[Equation 10] Since the initial phase θ _{2} of the frequency change component is obtained from the equation (8), the phase θ _{1} of the phase change component can be obtained from the following equation. Finally, by performing phase connection using the two types of initial phases θ _{1} and θ _{2} obtained by the equations (8) and (9), a phase distribution with high resolution can be obtained for each pixel.
The distributions of the initial phases θ _{1} , θ _{2} and the initial phase after the continuation are shown in FIGS. 3d, 3e, and 3f, respectively.
A phase connection method using two types of phase distribution will be described. The two types of initial phases θ _{1} and θ _{2} obtained above are
Both are repeated discontinuous values of 0 to 2π, and it is necessary to make the phase distribution continuous (phase connection) in order to obtain a unique value for the position. A method using a phase distribution of a plurality of pitches is often used as a method of performing phase connection, and in the present invention, phase connection is performed by using two types of initial phases θ _{1} and θ _{2} having different pitches. Two
Regarding the initial phases θ _{1} and θ _{2} of the types, the lattice numbers are k _{1} and k _{2,} and the values after phase connection are φ 1 and φ, respectively.
If the value is 2, the initial phase before and after the phase connection is expressed by the following relationship. φ _{1} = θ _{1} + 2πk _{1} φ _{2} = θ _{2} + 2πk _{2} (10) Further, φ1 and φ2 have a relationship shown by the following two expressions. _{φ 1 nφ 2 = θ 1 Mod} (nθ 2, 2π) + 2π (k 1 nk 2) (11)
[Equation 11]
Here, Mod (α, 2π) is the remainder obtained by dividing α by 2π.
And Mod (α, 2π) = α2π [α / 2π]
Define. ([] Indicates Gaussian symbol). Also, P_{1}:
P_{Two}= 3: 3n + 1, so n = [P_{Two}/ P_{1}]
It In Fig. 4, the phase distribution φ_{1}, Nφ_{Two}And θ_{1}, Mod
(Nθ_{Two}, 2π). From Fig. 4, θ_{ } _{1}And Mo
d (nθ_{Two}, 2π) changes depending on the position x
Therefore, from the relationships shown in equations (11) and (12), 0 ≦ φ
_{1}<6πP_{Two}/ P_{1}In the range of, φ1 is calculated by the following formula.
Can be turned on.
[Equation 12]
Realtime processing by dedicated hardware will be described. FIG. 5 is a diagram showing a hardware configuration for performing the shape measuring method according to the present invention at high speed. Reference grid slide 11, moving table 12, stepping motor 1
3, the projection lens 15, the CCD camera 18, the display device 19, and the measurement target object 20 are the reference grid slide 1, the moving table 2, the stepping motor 3, the projection lens 5, the CCD camera 8, the display device 9, and the measurement device in FIG. It is similar to the target object 10. The timing controller 16 changes the moving speed of the reference grid slide to the CCD
Adjusted to move by P _{2/3} for each frame rate of the camera 18, in synchronization with the photographing by the CCD camera 18 to emit strobe light source 14. In this way, it is possible to capture an image without blurring due to the movement of the grid.
FIG. 6 shows a frequency modulation grating phase analysis circuit 17
3 is a block diagram showing the configuration of FIG. The lattice image input from the CCD camera 18 is A / D converted by the A / D conversion unit 21, and then the switching unit 22 operates the frame memories I _{0 to} I _{8} according to the frame synchronization signal from the timing controller 16. Are sequentially stored in. By taking every three of these images and passing through the threedimensional phase calculation table T1, the initial phases Θ _{0} , Θ _{1} , and Θ _{2} including frequency changes can be immediately obtained. Further, by passing these through the threedimensional phase connection table T _{2} , the initial phase θ _{1} after continuation can be obtained immediately. Since one of the frame memories I _{0 to} I _{8} is updated every time an image of one frame is input, the phase image output from the table is also updated every frame.
The relationship between the input and output of the threedimensional phase table T _{1} is shown in the following formula.
[Equation 10] Formula (13) is calculated in advance for all combinations of inputs. Further, the threedimensional phase connection table T _{2} receives Θ _{0} , Θ _{1} , Θ _{2} obtained using the table T _{2} as an input and outputs the phase distribution φ _{1} after the continuation. A method of displaying a phase difference image will be described. In this method, the height distribution of the object is obtained by calculating the difference from the phase distribution on the reference plane. First, the switch S is turned on to store the phase distribution φ _{0} on the reference plane in the frame memory 23. Next, the switch S is turned off and the measurement target object 20 is photographed, so that the phase difference distribution image can be output in real time.
The shape measuring method according to the present invention operates correctly.
This is confirmed by the simulation described above.
It is clear from FIGS. 2 and 3 which are graphs showing the image and its distribution.
It's mild. Fig. 2 shows when P1: P2 = 3: 22.
Is an image of the frequency modulation grating projected onto the object of
Are respectively α = 0 and P_{Two}/ 3, 2P_{Two}/ 3, P_{Two},
4P_{Two}/ 3, 5P_{Two}/ 3, 2P_{Two}, 7P_{Two}/ 3, 8P_{Two}
It is an image at / 3. 3a, 3b, 3c
Is the phase distribution Θ containing the frequency change component, respectively._{ } _{0}, Θ
_{1}, Θ_{Two}Is. Figures 3d and 3e are derived from these
Two types of phase distribution θ_{1}, Θ_{Two}Is. Figure 3f
Phase distribution θ_{1}, Θ_{Two}With the phase distribution after continuation obtained using
is there. From these images, the 2 contained in the frequency modulation grating
Analyze the phase distributions of various types,
You can see that
FIG. 7 shows a frequency modulation grating projected on an actual object.
This is the result of measuring the shape of the object by casting a shadow. Figure 7a
This is the result of projecting the frequency modulation grating on the plaster image. Figure 7
b, 7c, and 7d are two types of phase distribution θ_{1},
θ_{Two}And the phase distribution φ after continuation_{ } _{1}Is. Figure 7e shows
Phase distribution of the reference plane (flat plate) obtained by the same method
φ_{1}'(After serialization). FIG. 7f shows the image of FIG.
And the phase difference distribution obtained from the image of FIG. 7e. This image
The height distribution of the object without phase wrapping
You can see that
FIG. 1 is a diagram showing a general configuration for executing a shape measuring method according to the present invention.
2A to 2I are images of a frequency modulation grating projected on a plane by simulation.
FIG. 3 is a phase distribution of a frequency modulation grating projected on a plane by simulation, a, b, and c are phase distributions of the frequency modulation grating, d is a phase distribution excluding a frequency change component, and e is a frequency. Is the initial phase of the change component,
f is the phase distribution after continuation.
FIG. 4 is a graph showing a phase distribution before and after phase connection.
FIG. 5 is a diagram showing a hardware configuration for performing the shape measuring method according to the present invention at high speed.
6 is a block diagram showing a configuration of a frequency modulation grating phase analysis circuit in FIG.
FIG. 7a is an image obtained by projecting a frequency modulation grating on a plaster image, which is the result of measuring the shape of an object.
FIG. 7b is a diagram showing two types of phase distributions, which are the results of shape measurement of an object.
FIG. 7c is a diagram showing two types of phase distributions, which are results of shape measurement of an object.
FIG. 7d is a diagram showing a phase distribution after continuation, which is a result of shape measurement of an object.
FIG. 7e is a diagram showing a phase distribution after the reference surface is made continuous, which is a result of shape measurement of an object.
FIG. 7f shows the resulting phase difference distribution.
─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 200383730 (JP, A) JP 2000105109 (JP, A) JP 11257930 (JP, A) JP 10122834 ( JP, A) JP 2003121124 (JP, A) JP 200290126 (JP, A) (58) Fields investigated (Int.Cl. ^{7} , DB name) G01B 11/24 G01B 11/25
Claims (3)
Steps of respectively obtaining a phase distribution relating to luminance, a phase distribution relating to the frequency, and a phase connection using a phase distribution relating to luminance, and the phaseconnected phase distribution corresponding to the height distribution of the measurement target object. A shape measuring method, comprising:
y) is the initial phase of the phase change component, θ _{2} (x, y) is the initial phase of the frequency change component, α is the moving distance of the lattice , P _{1} is the period of the phase change component, and P _{2} is the period of the frequency change component. In this case, the shape measuring method is characterized in that the following expression (1) is satisfied. [Equation 1]
Means for obtaining a phase distribution regarding brightness, a phase connection for using the phase distribution for the frequency, and a phase distribution for brightness, and the phase connection for the phase connection corresponding to the height distribution of the measurement target object A shape meter characterized by comprising:
Measuring device .
Priority Applications (1)
Application Number  Priority Date  Filing Date  Title 

JP2002057776A JP3536097B2 (en)  20020304  20020304  Method and apparatus for measuring grating projection shape using frequency modulation grating 
Applications Claiming Priority (1)
Application Number  Priority Date  Filing Date  Title 

JP2002057776A JP3536097B2 (en)  20020304  20020304  Method and apparatus for measuring grating projection shape using frequency modulation grating 
Publications (2)
Publication Number  Publication Date 

JP2003254732A JP2003254732A (en)  20030910 
JP3536097B2 true JP3536097B2 (en)  20040607 
Family
ID=28667962
Family Applications (1)
Application Number  Title  Priority Date  Filing Date 

JP2002057776A Active JP3536097B2 (en)  20020304  20020304  Method and apparatus for measuring grating projection shape using frequency modulation grating 
Country Status (1)
Country  Link 

JP (1)  JP3536097B2 (en) 
Cited By (1)
Publication number  Priority date  Publication date  Assignee  Title 

WO2013187203A1 (en)  20120612  20131219  株式会社島精機製作所  Threedimensional measurement apparatus, and threedimensional measurement method 
Families Citing this family (10)
Publication number  Priority date  Publication date  Assignee  Title 

JP2005147394A (en)  20031023  20050609  Sankyo Seiki Mfg Co Ltd  Dynamicpressure bearing device and disc driving device 
US20060072122A1 (en) *  20040930  20060406  Qingying Hu  Method and apparatus for measuring shape of an object 
JP2006170744A (en) *  20041215  20060629  Tohoku Techno Arch Co Ltd  Threedimensional distance measuring instrument 
KR100722245B1 (en)  20060323  20070529  주식회사 고영테크놀러지  Apparatus for inspecting for three dimension shape 
JP5137033B2 (en)  20070131  20130206  国立大学法人浜松医科大学  Surgery support information display device, surgery support information display method, and surgery support information display program 
DE102007034689B4 (en) *  20070712  20090610  Carl Zeiss Ag  Method and device for optically inspecting a surface on an object 
JP5561458B2 (en)  20080318  20140730  国立大学法人浜松医科大学  Surgery support system 
CN101451826B (en) *  20081217  20100609  中国科学院上海光学精密机械研究所  Object threedimensional contour outline measuring set and measuring method 
JP5569711B2 (en)  20090301  20140813  国立大学法人浜松医科大学  Surgery support system 
JP5243996B2 (en) *  20090302  20130724  スタンレー電気株式会社  Object detection device 

2002
 20020304 JP JP2002057776A patent/JP3536097B2/en active Active
Cited By (1)
Publication number  Priority date  Publication date  Assignee  Title 

WO2013187203A1 (en)  20120612  20131219  株式会社島精機製作所  Threedimensional measurement apparatus, and threedimensional measurement method 
Also Published As
Publication number  Publication date 

JP2003254732A (en)  20030910 
Similar Documents
Publication  Publication Date  Title 

Heide et al.  Diffuse mirrors: 3D reconstruction from diffuse indirect illumination using inexpensive timeofflight sensors  
EP2849149B1 (en)  Projection system, image processing device, and projection method  
JP3885458B2 (en)  Projected image calibration method and apparatus, and machinereadable medium  
JP3509652B2 (en)  Projector device  
DE102010029091B4 (en)  Form measuring device and method  
JP3961729B2 (en)  Allfocus imaging device  
US7630539B2 (en)  Image processing apparatus  
KR101152842B1 (en)  Threedimensional measurement device and board inspecting machine  
JP5643645B2 (en)  System and method for threedimensional measurement of the shape of a tangible object  
US7260270B2 (en)  Image creating device and image creating method  
DE3829925C2 (en)  Device for the optical measurement of teeth in the oral cavity  
JP4831703B2 (en)  Object displacement measurement method  
US9063283B2 (en)  Pattern generation using a diffraction pattern that is a spatial fourier transform of a random pattern  
JP4744610B2 (en)  3D measuring device  
US9322643B2 (en)  Apparatus and method for 3D surface measurement  
JP2014102246A (en)  Position attitude detection system  
CN105026997B (en)  Optical projection system, semiconductor integrated circuit and image correcting method  
US8115830B2 (en)  Image processing apparatus  
DE102015000386A1 (en)  Apparatus and method for measuring a threedimensional shape and nontransitory computerreadable storage medium  
US7454054B2 (en)  Threedimensional shape input device  
JP5576726B2 (en)  Threedimensional measuring apparatus, threedimensional measuring method, and program  
US7911505B2 (en)  Detecting illuminant flicker  
KR100835759B1 (en)  Image projector, inclination angle detection method, and projection image correction method  
JP4917351B2 (en)  Calibration method in threedimensional shape measuring apparatus  
US9692958B2 (en)  Focus assist system and method 
Legal Events
Date  Code  Title  Description 

A521  Written amendment 
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20040106 

TRDD  Decision of grant or rejection written  
A01  Written decision to grant a patent or to grant a registration (utility model) 
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20040217 

R150  Certificate of patent or registration of utility model 
Free format text: JAPANESE INTERMEDIATE CODE: R150 

S111  Request for change of ownership or part of ownership 
Free format text: JAPANESE INTERMEDIATE CODE: R313111 

R350  Written notification of registration of transfer 
Free format text: JAPANESE INTERMEDIATE CODE: R350 