CN106840039B - A kind of quick three-dimensional measurement method based on composite grating projection - Google Patents

A kind of quick three-dimensional measurement method based on composite grating projection Download PDF

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CN106840039B
CN106840039B CN201710141583.3A CN201710141583A CN106840039B CN 106840039 B CN106840039 B CN 106840039B CN 201710141583 A CN201710141583 A CN 201710141583A CN 106840039 B CN106840039 B CN 106840039B
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phase
grating
echelon
wrapped
composite grating
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CN106840039A (en
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马孟超
姚鹏程
邓华夏
张进
于连栋
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Hefei University of Technology
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Hefei University of Technology
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    • G—PHYSICS
    • 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
    • G01B11/25—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures by projecting a pattern, e.g. one or more lines, moiré fringes on the object
    • G01B11/254—Projection of a pattern, viewing through a pattern, e.g. moiré

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  • Computer Vision & Pattern Recognition (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The present invention relates to the quick three-dimensional measurement methods projected based on composite grating, comprising: builds measuring system；The generation of composite grating is carried out, and is burned onto optical projection system；Composite grating projects measured object surface, and modulation generates the composite grating of new shape；New shape composite grating is acquired, and is transmitted in computer processing system；By five step phase shift method solution phases, cosine grating wrapped phase and echelon wrapped phase are obtained respectively；Echelon wrapped phase is subjected to rounding processing, and combines cosine grating wrapped phase that wrapped phase is launched into absolute phase；The reconstruction of object dimensional information is carried out by absolute phase non-linear relation corresponding with measured object depth.The present invention only needs to carry out the projection and acquisition of one group of five amplitude grating picture, and can be carried out the expansion of object phase by a five step phase shift methods；Method proposed by the present invention reduces the use of grating picture number, improves measuring speed with identical measurement accuracy.

Description

A kind of quick three-dimensional measurement method based on composite grating projection
Technical field
The present invention relates to quick three-dimensional field of measuring technique, especially a kind of quick three-dimensional based on composite grating projection is surveyed Amount method.
Background technique
In recent years, optical three-dimensional measurement technology because it has high-precision, with testee non-contacting advantage due to obtain it is fast The development of speed, with the development of computer technology, information technology and digitizing technique, by optical projection system, industrial camera and calculating The projecting structural optical three-dimension measuring system of machine processing system composition comes into being.
Projection measurement method based on Gray code is produced, based on the decoded throwing of neighborhood by many years research of numerous scholars Image measuring method, digital projection technique method based on phase etc..Wherein, based on the digital projection technique of phase because of its measurement speed Degree is fast, is able to carry out fine and close reconstruction, relative accuracy is higher, therefore has biggish development potentiality.Because of phase and depth There are non-linear relations, so most important step is that acquisition is continuous exhausted for the digital projection technique based on phase To phase.The different digital rasters with phase information is projeced on testee first in terms of realization, is then passed through Camera carries out data acquisition to the phase grating of projection, and the absolute phase of object, Jin Erke are obtained by solving phase processor accordingly It is a kind of to have the advantages that multiple method for three-dimensional measurement to obtain the depth information of object by non-linear relation.
By the research of lot of domestic and foreign scholar, the method for obtaining absolute phase now has two major classes method substantially, a kind of Method is to carry out phase acquisition using space neighborhood information, and such methods error is excessive, can not carry out good practical application.More More research is for another kind of method, and this kind of methods are to carry out phase unwrapping using time-domain information, in camera shooting speed Under the premise of limited and guarantee measurement accuracy, present relatively good projection three-dimensional measurement method at least needs to project six amplitude gratings Picture just can be carried out the expansion of absolute phase.Less grating picture has been used there are also some, but since grating is sparse etc. Reason, so that the precision for obtaining phase method is relatively low.
Summary of the invention
The purpose of the present invention is to provide one kind under the premise of keeping precision, effectively raises the speed of three-dimensional measurement Based on composite grating projection quick three-dimensional measurement method.
To achieve the above object, the invention adopts the following technical scheme: a kind of quick three based on composite grating projection Measurement method is tieed up, this method includes the steps that following order:
(a) measuring system being made of optical projection system, industrial camera and computer processing system is put up；
(b) generation of composite grating is carried out in computer processing system, and the composite grating is passed through into computer disposal System is burned onto optical projection system；
(c) for the composite grating by projection system projects to measured object surface, composite grating is high by measured object surface Degree modulation generates the composite grating of new shape；
(d) the new shape composite grating described with industrial camera acquisition, and the composite grating of the new shape of acquisition is transmitted Into computer processing system；
(e) in computer processing system, the composite grating of the new shape by industrial camera acquisition passes through five step phase shifts Method solution phase obtains cosine grating wrapped phase and echelon wrapped phase respectively；
(f) the echelon wrapped phase that will acquire carries out rounding processing, and wraps up phase in conjunction with the cosine grating Wrapped phase is launched into absolute phase by position；
(g) weight of object dimensional information is carried out by absolute phase non-linear relation corresponding with measured object depth It builds.
In the step (a), the measuring system has synchronous Trigger Function, can acquire the light projected away moment Grid are simultaneously sent to computer processing system.
In the step (b), the composite grating is the single cosine grating and single ladder light by specific period ratio What grid were combined under single Color Channel, the calculation formula of intensity profile is as follows:
Ik(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)-r×kπ/5]+I”'(x,y)cos[φs(x,y)-s× kπ/5] (1)
Wherein, (x, y) indicates that pixel coordinate, I ' (x, y) indicate composite grating background intensity, and I " (x, y) indicates cosine light The modulate intensity of grid, I " ' (x, y) indicate the modulate intensity of echelon, φrIndicate that cosine grating wrapped phase, r indicate cosine The scale factor of grating phase-shift phase, φsIndicate that echelon wrapped phase, s indicate the scale factor of echelon phase-shift phase, Ik (x, y) expression kth width composite grating, k=0,1,2,3,4.
In the step (e), the calculation formula of the five steps phase shift method is as follows:
Wherein, (x, y) indicates pixel coordinate, φr(x, y) indicates that cosine grating wrapped phase, r indicate cosine grating phase shift The scale factor of amount, φs(x, y) indicates that echelon wrapped phase, s indicate the scale factor of echelon phase-shift phase, Ik(x, Y) expression kth width composite grating, k=0,1,2,3,4.
In the step (f), the calculation formula of the rounding processing are as follows:
K (x, y)=round [5 φs(x,y)/2π] (3)
Wherein, φsAfter (x, y) indicates that echelon wrapped phase, round indicate that rounding function, K (x, y) indicate rounding Echelon wrapped phase；
The calculation formula of the absolute phase is as follows:
Φw(x, y)=φr(x,y)+K(x,y)·2π (4)
Wherein, φr(x, y) indicates that cosine grating wrapped phase, K (x, y) indicate the echelon wrapped phase after rounding, Φw(x, y) indicates absolute phase.
As shown from the above technical solution, the present invention has the advantages that first, the present invention only needs to carry out one group of five amplitude grating The projection and acquisition of picture, and can be carried out by a five step phase shift methods expansion of object phase；Second, the present invention proposes Method compared with traditional preferable time domain unpacking method, with identical measurement accuracy, The present invention reduces light The use of grid picture number, improves measuring speed.
Detailed description of the invention
Fig. 1 is the composite grating figure that the present invention uses；
Fig. 2 (a) is the whole composite grating figure of SNR=22 interference, and Fig. 2 (b) is no SNR composite grating interfered and SNR The local contrast figure of the composite grating sum of=22 interference；
Fig. 3 is cosine wrapped phase figure；
Fig. 4 is ladder wrapped phase figure；
Fig. 5 is the rounding ladder wrapped phase figure of emulation；
Fig. 6 is the absolute phase figure of emulation；
Fig. 7 is measuring system figure；
Fig. 8 is the pictorial diagram of acquisition；
Fig. 9 is the wrapped phase figure of measured object；
Figure 10 is the absolute phase figure of measured object；
Figure 11 is measured object three-dimensional information rendering figure.
Specific embodiment
Embodiment one
The present embodiment is simulated measurement, and all processes are handled in a computer, and here is specific simulation process:
Step 1: the composite grating that the present invention is designed passes through MATLAB Software Create, the composite grating intensity profile of design It is shown below, shape is as shown in Figure 1.
I1(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)-4π/5]+I”'(x,y)cos[φs(x,y)-8π/5]
I2(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)-2π/5]+I”'(x,y)cos[φs(x,y)-4π/5]
I3(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)]+I”'(x,y)cos[φs(x,y)]
I4(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)+2π/5]+I”'(x,y)cos[φs(x,y)+4π/5]
I5(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)+4π/5]+I”'(x,y)cos[φs(x,y)+8π/5]
Wherein, (x, y) indicates pixel coordinate, I'(x, y) indicate raster back color intensity, I " (x, y) indicates cosine grating Modulate intensity, I " ' (x, y) indicate the modulate intensity of echelon, φr(x, y) indicates cosine grating wrapped phase, φs(x,y) Indicate that echelon wrapped phase, the phase-shift phase of cosine grating are 2 π/5, the phase-shift phase of echelon is 4 π/5.
Step 2: the composite grating of generation being added to the interference of SNR=22, shown in image shape such as Fig. 2 (a)；SNR= The composite grating figure comparison that 22 composite grating figure is interfered with no SNR is as shown in Fig. 2 (b).
Step 3: the composite grating being interfered being handled with MATLAB software, is carried out at five step phase shift methods first Reason, treatment process are shown below:
Wherein, φr(x, y) indicates cosine grating wrapped phase, φs(x, y) indicates echelon wrapped phase, solution Cosine grating wrapped phase is as shown in figure 3, the echelon wrapped phase solved is as shown in Figure 4.
Step 4: echelon wrapped phase is subjected to rounding, shape such as Fig. 5 institute after rounding by process described in following formula Show.
K (x, y)=round [5 φs(x,y)/2π]
Wherein, round indicates rounding function, φsAfter (x, y) indicates that echelon wrapped phase, K (x, y) indicate rounding Echelon wrapped phase.
Step 5: by the echelon wrapped phase of rounding and cosine grating wrapped phase by process described in following formula into Row combines, and ultimately forms absolute phase, shape is as shown in Figure 6, it can be seen that the absolute phase solved in the case where SNR=22 Although there is a small amount of noise spot in position, overall, the absolute phase that solves or relatively good has extremely strong anti-dry Disturb ability.
Φw(x, y)=φr(x,y)+K(x,y)·2π
Wherein, Φw(x, y) indicates absolute phase, and K (x, y) indicates the ladder wrapped phase after rounding, φr(x, y) is indicated Cosine grating wrapped phase.
Embodiment two
The present embodiment is shooting measurement in kind, this measurement distance in kind is 500mm or so, detailed process is as follows institute Show:
Step 1: as shown in fig. 7, putting up the measurement system being made of optical projection system, industrial camera, computer processing system System, optical projection system, industrial camera are connected by data line and capture card with computer processing system.In this measuring system In, the LightCrafter 4500, industrial camera model IO of projector model TI (Texas Instrument) the company exploitation of selection The 2M360CL of company includes MATLAB programming software, operation projector and the software of industrial camera etc. in computer system.
Step 2: the composite grating of design is passed through into MATLAB Software Create, the composite grating gray scale of design such as following formula institute Show, shape is as shown in Figure 1.
I1(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)-4π/5]+I”'(x,y)cos[φs(x,y)-8π/5]
I2(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)-2π/5]+I”'(x,y)cos[φs(x,y)-4π/5]
I3(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)]+I”'(x,y)cos[φs(x,y)]
I4(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)+2π/5]+I”'(x,y)cos[φs(x,y)+4π/5]
I5(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)+4π/5]+I”'(x,y)cos[φs(x,y)+8π/5]
Wherein, (x, y) indicates pixel coordinate, I'(x, y) indicate raster back color intensity, I " (x, y) indicates cosine grating Modulate intensity, I " ' (x, y) indicate the modulate intensity of echelon, φr(x, y) indicates cosine grating wrapped phase, φs(x,y) Indicate that echelon wrapped phase, the phase-shift phase of cosine grating are 2 π/5, the phase-shift phase of echelon is 4 π/5.
Step 3: the composite grating of generation is thrown into optical projection system, and to object by computer system burning It penetrates.
Step 4: being reflected by the object composite grating back with industrial camera acquisition, and synchronous transfer is to computer disposal system In system, the collected composite grating of industrial camera is as shown in Figure 8.
Step 5: in computer processing system, collected composite grating being passed through into five step phase shift methods, treatment process It is shown below:
Wherein, φr(x, y) indicates cosine grating wrapped phase, φs(x, y) indicates echelon wrapped phase, solves Cosine grating wrapped phase and echelon wrapped phase are as shown in Figure 9.
Step 6: echelon wrapped phase is subjected to rounding by process described in following formula.
K (x, y)=round [5 φs(x,y)/2π]
Wherein, Round indicates rounding function, φsAfter (x, y) indicates that echelon wrapped phase, K (x, y) indicate rounding The echelon wrapped phase.
Step 7: by the echelon wrapped phase of rounding and cosine grating wrapped phase by process described in following formula into Row combines, and ultimately forms absolute phase, shape is as shown in Figure 10.
Φw(x, y)=φr(x,y)+K(x,y)·2π
Wherein, Φw(x, y) indicates object absolute phase, and K (x, y) indicates the ladder wrapped phase after rounding, φr(x,y) Indicate cosine grating wrapped phase.
Step 8: object three is carried out by the absolute phase and the one-to-one non-linear relation of depth and calibration process The reconstruction of information is tieed up, the object dimensional pattern of reconstruction is as shown in figure 11.
In conclusion the present invention only needs to carry out the projection and acquisition of one group of five amplitude grating picture, and pass through five steps Phase shift method can be carried out the expansion of object phase；Method proposed by the present invention compared with traditional preferable time domain unpacking method, With identical measurement accuracy, The present invention reduces the uses of grating picture number, improve measuring speed.

Claims (1)

1. a kind of quick three-dimensional measurement method based on composite grating projection, this method include the steps that following order:
(a) measuring system being made of optical projection system, industrial camera and computer processing system is put up；
(b) generation of composite grating is carried out in computer processing system, and the composite grating is passed through into computer processing system It is burned onto optical projection system；
(c) composite grating passes through measured object apparent height tune by projection system projects to measured object surface, composite grating System generates the composite grating of new shape；
(d) the new shape composite grating described with industrial camera acquisition, and the composite grating of the new shape of acquisition is transmitted to meter In calculation machine processing system；
(e) in computer processing system, the composite grating of the new shape by industrial camera acquisition passes through five step phase shift method solutions Phase obtains cosine grating wrapped phase and echelon wrapped phase respectively；
(f) the echelon wrapped phase that will acquire carries out rounding processing, and will in conjunction with the cosine grating wrapped phase Wrapped phase is launched into absolute phase；
(g) reconstruction of object dimensional information is carried out by absolute phase non-linear relation corresponding with measured object depth；? In the step (a), the measuring system has synchronous Trigger Function, can acquire the grating projected away moment and be sent to Computer processing system；
In the step (b), the composite grating is existed by the single cosine grating and single echelon of specific period ratio It is combined under single Color Channel, the calculation formula of intensity profile is as follows:
Ik(x, y)=I'(x, y)+I " (x, y) cos [φr(x,y)-r×kπ/5]+I”'(x,y)cos[φs(x,y)-s×kπ/ 5] (1)
Wherein, (x, y) indicates that pixel coordinate, I ' (x, y) indicate composite grating background intensity, and I " (x, y) indicates cosine grating Modulate intensity, I " ' (x, y) indicates the modulate intensity of echelon, φrIndicate that cosine grating wrapped phase, r indicate cosine grating The scale factor of phase-shift phase, φsIndicate that echelon wrapped phase, s indicate the scale factor of echelon phase-shift phase, Ik(x,y) Expression kth width composite grating, k=0,1,2,3,4；
In the step (e), the calculation formula of the five steps phase shift method is as follows:
Wherein, (x, y) indicates pixel coordinate, φr(x, y) indicates that cosine grating wrapped phase, r indicate cosine grating phase-shift phase Scale factor, φs(x, y) indicates that echelon wrapped phase, s indicate the scale factor of echelon phase-shift phase, Ik (x, y) table Show kth width composite grating, k=0,1,2,3,4；
In the step (f), the calculation formula of the rounding processing are as follows:
K (x, y)=round [5 φs(x,y)/2π] (3)
Wherein, φs(x, y) indicates that echelon wrapped phase, round indicate that rounding function, K (x, y) indicate the ladder after rounding Grating wrapped phase；
The calculation formula of the absolute phase is as follows:
Φw(x, y)=φr(x,y)+K(x,y)·2π (4)
Wherein, φr(x, y) indicates that cosine grating wrapped phase, K (x, y) indicate the echelon wrapped phase after rounding, Φw (x, y) indicates absolute phase.
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