CN100554869C - A kind of two dimension three based on color structured light is separated phase measuring method frequently - Google Patents

Abstract

A kind of two dimension three based on color structured light is frequently separated phase measuring method, and step is: 1. prepare the grating that three width of cloth are formed by two kinds of identical sinusoidal photoreactivation of different three primary colors of frequency; 2. projection grating utilizes two identical ccd video cameras to take to testee, obtains 24 photos; 3. the photo of taking is separated phase, obtain the directions X of each pixel on each photo and the phase value on the Y direction; 4. two phase values are mated, calculate the three-dimensional coordinate of each point.The present invention has overcome defective and the not high shortcoming of matching precision of only encoding on the direction, makes codes match more effective and accurate.Avoided in the mechanical measuring means because the caused measuring error of juxtaposition metamorphose has improved measuring accuracy; Need not to obtain three-dimensional information, improved measuring speed by two-dimensional scan; Can write down the color information of object simultaneously, make reverse engineering further extend to the counter of object color and ask from obtaining of object dimensional shape.

Description

A kind of two dimension three based on color structured light is separated phase measuring method frequently

Technical field

The invention belongs to the reverse-engineering fields of measurement, be specifically related to a kind of two dimension three and separate phase measuring method frequently based on color structured light.

Background technology

Binocular formula optical grating projection structural light measurement method is present more advanced a kind of measuring method, it combines structured light method and stereo vision method, projecting beam forms structured light by optical grating projection at body surface, the spatial information of testee becomes striated pattern through structure light coding, these deforming stripes are by two the ccd video camera records angled with the projector center, a series of projection gratings according to record are encoded to each spatial point of measurement space, process decoding and phase calculation obtain the coded message and the phase information of each spatial point, thereby determine its locus, obtain measurement space information.In the stereoscopic vision matching process, on the corresponding photo that left and right cameras is taken feature how can be clearly, the correspondence of unambiguity, be the key point of dealing with problems.Wherein coding method and phase demodulation technique play crucial effects in the data of structured light projection method are obtained, and affect measuring accuracy, speed and the reliability of system.

In optical grating projection is measured, commonly used is to adopt the Gray coding, it only can carry out limited cutting apart to the space, each bar grating pair is answered a discrete value, measurement space point also only can obtain limited space encoding value, therefore the encoded radio that can duplicate in one direction adopts the Gray code efficiency not high separately.Some adopts four step phase-shift methods of one dimension, and in the phase shifting method of projection grating, each pixel in the document image can obtain a relative phase

It is unique in cycle at a relative phase of phase shift, but should value in whole measurement space not unique, the matching result precision that this method draws be not high, and just to mating on the one dimension direction.And the coupling of two-dimensional space is difficult to be competent at.Therefore must the phase value of spatial point be launched, promptly separate phase.Promptly in traditional coding and dimension solutions phase method, about in two photos, the corresponding relation of unique point can't uniquely be determined, must retrain by other, about the corresponding relation of two photos unique points is just unique determines.

Summary of the invention

The object of the present invention is to provide a kind of two dimension three frequently to separate phase measuring method based on color structured light, this method efficient height, the precision height, and be easy to the coupling to two-dimensional space.

Two dimension three based on color structured light provided by the invention is frequently separated phase measuring method, and its step comprises:

(1) preparation three amplitude gratings, grating forms by the sinusoidal photoreactivation with same frequency on sinusoidal light on the directions X and the Y direction, and two kinds of sinusoidal light on X, the Y direction are different three primary colors, and three amplitude gratings satisfy the requirement of formula (I)

${\mathrm{\λ}}_{123}=\frac{{\mathrm{\λ}}_{12}{\mathrm{\λ}}_{23}}{{\mathrm{\λ}}_{12}-{\mathrm{\λ}}_{23}}=1---\left(I\right)$

λ ₁₂And λ ₂₃Be respectively λ ₁, λ ₂Stack and λ ₂, λ ₃More low-frequency phase function Φ that stack obtains ₁₂(x) and Φ ₂₃(x) pairing frequency, λ ₁₂₃(x) be to λ ₁₂And λ ₂₃Stack obtains more low frequency function phi ₁₂₃(x) pairing frequency, wherein λ _jBe respectively the sine wave phase function phi of three amplitude gratings ₁(x), Φ ₂(x), Φ ₃(x) frequency, and different, j=1,2,3;

(2) projection one amplitude grating forms the grating fringe that is out of shape to testee at body surface, utilizes two identical ccd video cameras to take, the angular range of two ccd video cameras is the 0-180 degree, again with the mobile respectively pi/2 of this amplitude grating, π, 3 pi/2s, and take respectively, obtain four photos; Other two amplitude grating is carried out same operation, and each grating obtains four photos respectively;

(3) 12 photos of a ccd video camera being taken according to following process are separated phase:

(3.1) from photo, isolate primaries on the two-dimensional directional, from primaries, separate a kind of single original colored light;

(3.2) adopt four step phase-shift methods to obtain the principal phase value of pixel on the photo, utilize again four the step phase-shift methods with grating on the vertical direction of grid line translation pitch 1/4, then in the light intensity expression of formula (1) phase place with mobile pi/2, equidistant translation 3 times, obtain 4 amplitude grating projected images, and calculate the relative phase of each pixel in each amplitude grating projected image

With

Wherein, I _JiBe light intensity value, i=1,2,3,4, j=1,2,3;

(3.3) be λ to frequency ₁, λ ₂Two grating fringe image additions, find the solution the phase place Φ of two kinds of stripeds ₁, Φ ₂ ¹To frequency is λ ₂, λ ₃Two grating fringe image additions, find the solution the phase place Φ of two kinds of stripeds ₂ ², Φ ₃

(3.4) to Φ ₂ ¹, Φ ₂ ²Average, obtain the whole audience phase value Φ of the second amplitude grating bar graph ₂, according to whole audience phase value Φ ₂Obtain the phase place grey level on the directions X;

(3.5) to separating another kind of single original colored light, repeating step (3.2) obtains the phase place grey level on the Y direction to (3.4);

(3.6) according to the phase place grey level of testee pictures taken on directions X and Y direction, obtain the directions X of each pixel and the phase value on the Y direction (u, v);

(4) 12 photos of another ccd video camera being taken according to step (3.1) to (3.6) are separated phase, obtain the directions X of each pixel on each photo and the phase value on the Y direction (u ', v ');

(5) (u, v), (u ', v ') mates, according to the inside and outside parameter of match point and CCD, calculates the three-dimensional coordinate of each point to the phase value of the pixel of above-mentioned two captured images of CCD.

The method of the present invention's employing binocular stereo vision and phase shift method combination is carried out the coding on the two-dimensional directional.Overcome defective and the not high shortcoming of matching precision of only encoding on the direction, made codes match more effective and accurate.And this measuring method frequently separates phase based on the two dimension three of color structured light, avoided in the mechanical measuring means because the caused measuring error of juxtaposition metamorphose has improved measuring accuracy; Compare with additive method simultaneously, need not to obtain three-dimensional information, improved measuring speed by two-dimensional scan.Can write down the color information of object simultaneously, the pattern that can only obtain object before having remedied and can not obtain the defective of the color of object makes reverse engineering further extend to the counter of object color from obtaining of object dimensional shape and asks.

Description of drawings

Fig. 1 is the schematic flow sheet of the inventive method;

The coding pattern that Fig. 2 the present invention is used;

Fig. 3 is red light and the green light pattern of separating;

Fig. 4 is four step phase-shift method schematic diagrams;

Fig. 5 is for frequently separating facies principle figure based on three of four step phase-shift methods;

Fig. 6 is the phase place sketch on u direction;

Fig. 7 is the phase place sketch on the v direction.

Fig. 8 is the schematic diagram of three-dimensional measurement.

Embodiment:

Projection forms structured light through the sinusoidal light field of the colorama of ovennodulation at body surface, is exactly the X in projection, on the Y direction, all has the different grating of three amplitude-frequency rates to carry out projection.Projection goes out colored area-structure light, and it is composited (this can change, so long as one or two kind of three kinds of Essential colour gets final product) by green glow and ruddiness, and wherein, ruddiness light intensity on directions X is Sine distribution, and green glow light intensity on the Y direction is Sine distribution.Note by left and right cameras, utilize image processing to isolate two images on the two-dimensional directional, the photo that obtains is decoded, realize accurate coupling the information of volume coordinate point in conjunction with the phase shift method.The camera interior and exterior parameter that utilization calibrates according to matching result is asked for the three-dimensional coordinate of spatial point then.This technique guarantee is understood the accuracy of phase, and does not rely on limit constraint, has guaranteed the stable of algorithm.

The present invention is further detailed explanation with example with reference to the accompanying drawings below.

As shown in Figure 1, the inventive method may further comprise the steps:

(1) preparation three amplitude gratings

Grating requires: formed by the green sinusoidal photoreactivation with same frequency on red sinusoidal light on the directions X and the Y direction, (this can change, so long as two kinds of three kinds of Essential colour get final product), prepare three amplitude gratings altogether, the coding pattern grating is as shown in Figure 2.

This three amplitude gratings sine wave phase is made as Φ ₁(x), Φ ₂(x), Φ ₃(x); λ wherein ₁, λ ₂, λ ₃Be respectively phase function Φ ₁(x), Φ ₂(x), Φ ₃(x) different frequency.To λ ₁, λ ₂And λ ₂, λ ₃Use heterodyne technology to obtain more low-frequency phase function Φ respectively respectively ₁₂(x) and Φ ₂₃(x), use heterodyne technology to obtain more low frequency function phi again ₁₂₃(x) make λ ₁₂₃(x)=1.Φ ₁₂₃(x) frequency lambda ₁₂₃Can be expressed as through calculating:

${\mathrm{\λ}}_{123}=\frac{{\mathrm{\λ}}_{12}{\mathrm{\λ}}_{23}}{{\mathrm{\λ}}_{12}-{\mathrm{\λ}}_{23}}$

Must select suitable λ ₁, λ ₂λ ₃Value makes λ ₁₂₃=1.

(2) projection grating and pictures taken

To testee, form the grating fringe of distortion by projector projection first amplitude grating at body surface.

(2.1) these deforming stripes are by two the ccd video camera records angled with the projector center.Each CCD writes down a width of cloth picture.

(2.2) this amplitude grating is moved pi/2, be transmitted to the testee surface, the CCD camera is taken once again;

(2.3) grating is moved to pi/2 successively, move 3 times altogether, each mobile CCD camera all will be taken once.

(2.4) according to three amplitude gratings of top method projection successively to body surface, every projection once, CCD will take once.Each CCD has taken 12 photos like this, and photographic intelligence stores in the computer.

(3). separate phase

Being decoded by 12 width of cloth pictures that the last step obtains, is exactly the X in projection, on the Y direction, all has the different grating of three amplitude-frequency rates to carry out projection.Our projection goes out colored area-structure light, and it is composited by green glow and ruddiness.Its detailed process is:

(3.1) from colorama, isolate red, green glow on the two-dimensional directional, as shown in Figure 3.

Isolating ruddiness earlier, is the attached value of green information 0, so just can separate ruddiness.With same method green glow is separated.Here we will decode in conjunction with four step phase-shift methods, utilize one dimension three frequency phase demodulation techniques to separate respectively mutually then respectively on the image of ruddiness and green glow and calculate.

(3.2) the red image light analysis that the first step is separated, adopt four step phase-shift methods to obtain the principal phase value of pixel. four step phase-shift methods with grating on the vertical direction of grid line translation pitch 1/4, as shown in Figure 4, then in the light intensity expression of formula (1) phase place with mobile pi/2, equidistant translation 3 times, obtain 4 width of cloth images, the light intensity function of its i width of cloth image is:

When N=4, the light intensity function that respectively goes on foot of acquisition is:

Can get by formula (3) to (6):

I wherein _i(i=1,2,3,4) are light intensity value.

We have just obtained the relative phase of each pixel in the first amplitude grating projected image like this

(3) utilize four step phase-shift methods to calculate their principal phase value to the raster image of frequency 2 and the raster image of frequency 3, obtain

With

(4) the principal phase value of three frequencies that draw according to the last step utilizes three to separate the expansion of finishing phase place mutually frequently, its principle as shown in Figure 5, its detailed process is:

(4.1) one, the grating fringe image addition of 2 two kind of frequency is found the solution the phase place Φ of two kinds of stripeds ₁, Φ ₂ ¹

(4.2) two, the grating fringe image addition of 3 two kind of frequency is found the solution the phase place Φ of two kinds of stripeds ₂ ², Φ ₃

(4.3) Φ ₂ ¹, Φ ₂ ²The whole audience phase value Φ that averages and obtain the second amplitude grating bar graph ₂

(4.4) according to whole audience phase value Φ ₂Obtain the phase place grey level on the u direction, as shown in Figure 6.

(4.5) more isolated green light is separated calculating mutually according to the step of (4.2), (4.3), (4.4) with method, obtain the phase place grey level on the v direction, as shown in Figure 7.

(4.6) obtained the directions X of each pixel on the testee pictures taken and the phase value on the Y direction by above step, promptly the two-dimensional coordinate phase value of each pixel (u, v).

(4.7) according to the order of steps of (4.1) to (4.6) photo of second CCD shooting is carried out Treatment Analysis, obtain the directions X of each pixel of second captured image of CCD and the phase value on the Y direction, (u ', v ').

(5) search matched of picture element

The phase place coordinate of the pixel of two captured images of CCD that drew by the last step (u, v), (u ', v ') mate.When the coordinate of two pixels is equal or very close, then can think the point pairing picture point under different CCD on the same object.Its detailed process is:

(5.1) on first photos, each picture point all has the encoded radio of a two dimension corresponding with it, converts decimal number to by this binary number, then obtain this zone go up unique coordinate (u, v).

(5.2) find the zone that has the same coordinate with it on the image that the another one camera is become, find and the unique point of its coupling (u ', v '), the picture point of space object on two cameras can be found out like this.

To each pixel of digital picture { f (i, j) } (i, coordinate j) (u v), investigates phase place coordinate on another image (u ', v ') respectively, the minimum value of getting the gray scale difference between these pixels and pixel as unique point operator value G (i, j).Wherein G (i j) is:

G (i, j)=min{|f (i+k, j)-f (i, j) |, k=± 3,4 ... n} gets ultimate value THg, does as judging: if G (i, j) 〉=THg, then (i j) is unique point, and G (i, j) } be the unique point image.Then can match a little.Calculate the three-dimensional coordinate of each point according to the inside and outside parameter of match point and CCD.As shown in Figure 8.

Claims (1)

1, a kind of two dimension three based on color structured light is frequently separated phase measuring method, and its step comprises:

(1) preparation three amplitude gratings, grating forms by the sinusoidal photoreactivation with same frequency on sinusoidal light on the directions X and the Y direction, and two kinds of sinusoidal light on X, the Y direction are different three primary colors, and three amplitude gratings satisfy the requirement of formula (I)

${\mathrm{\λ}}_{123}=\frac{{\mathrm{\λ}}_{12}{\mathrm{\λ}}_{23}}{{\mathrm{\λ}}_{12}-{\mathrm{\λ}}_{23}}=1---\left(I\right)$

λ ₁₂And λ ₂₃Be respectively λ ₁, λ ₂Stack and λ ₂, λ ₃More low-frequency phase function Φ that stack obtains ₁₂(x) and Φ ₂₃(x) pairing frequency, λ ₁₂₃(x) be to λ ₁₂And λ ₂₃Stack obtains more low frequency function phi ₁₂₃(x) pairing frequency, wherein λ _jBe respectively the sine wave phase function phi of three amplitude gratings ₁(x), Φ ₂(x), Φ ₃(x) frequency, and different, j=1,2,3;

(2) projection one amplitude grating forms the grating fringe that is out of shape to testee at body surface, utilizes two identical ccd video cameras to take, the angular range of two ccd video cameras is the 0-180 degree, again with the mobile respectively pi/2 of this amplitude grating, π, 3 pi/2s, and take respectively, obtain four photos; Other two amplitude grating is carried out same operation, and each grating obtains four photos respectively;

(3) 12 photos of a ccd video camera being taken according to following process are separated phase:

(3.1) from photo, isolate monochromatic light on the two-dimensional directional;

(3.2) adopt four step phase-shift methods to obtain the principal phase value of pixel on the photo: utilize four step phase-shift methods with grating on the vertical direction of grid line translation pitch 1/4, then in the light intensity expression of formula (1) phase place with mobile pi/2, equidistant translation 3 times, obtain 4 amplitude grating projected images, and calculate the relative phase of each pixel in each amplitude grating projected image

With

Wherein, I _JiBe light intensity value, i=1,2,3,4, j=1,2,3;

(3.3) be λ to frequency ₁, λ ₂Two grating fringe image additions, find the solution the phase place Φ of two kinds of stripeds ₁, Φ ₂ ¹To frequency is λ ₂, λ ₃Two grating fringe image additions, find the solution the phase place Φ of two kinds of stripeds ₂ ², Φ ₃

(3.4) to Φ ₂ ¹, Φ ₂ ²Average, obtain the whole audience phase value Φ of the second amplitude grating bar graph ₂, according to whole audience phase value Φ ₂Obtain the phase place grey level on the directions X;

(3.5) to separating another kind of single original colored light, repeating step (3.2) obtains the phase place grey level on the Y direction to (3.4);

(3.6) according to the phase place grey level of testee pictures taken on directions X and Y direction, obtain the directions X of each pixel and the phase value on the Y direction (u, v);

(4) 12 photos of another ccd video camera being taken according to step (3.1) to (3.6) are separated phase, obtain the directions X of each pixel on each photo and the phase value on the Y direction (u ', v ');

(5) (u, v), (u ', v ') mates, according to the inside and outside parameter of match point and CCD, calculates the three-dimensional coordinate of each point to the phase value of the pixel of above-mentioned two captured images of CCD.

Images