CN103697834A - Automatic identification and elimination method for invalid points in dynamic scene during real-time optical three-dimensional measurement - Google Patents

Abstract

The invention provides an automatic identification and elimination method for invalid points in a dynamic scene during real-time optical three-dimensional measurement. According to the invention, a phase shift figure, a raster stripe and a phase modulation figure which are worked out by utilizing an N step phase-shift method and a dual-frequency time phase method, and a Gaussian filter are adopted to detect invalid points. The elimination method provided by the invention efficiently eliminates invalid points caused by movement of objects and unstable measurement environment, thereby remarkably improving the precision of the measuring result.

Description

Automatic identification and the method for removing of dynamic scene Null Spot in real-time optical three-dimensional measurement

Technical field

The invention belongs to field of optical measuring technologies, be specifically related to automatic identification and the method for removing of dynamic scene Null Spot in a kind of real-time optical three-dimensional measurement.

Background technology

In recent years along with the developing rapidly of digital projection device, utilize the projector of processing (DPL) technology based on digital light to generate and control grating fringe and become more and more convenient.Therefore, have high resolving power, low cost, the fireballing real-time three-dimensional measuring system based on digital raster fringe projection of projection the numerous areas such as industrial detection, Rapid Reverse Engineering, biomedicine, amusement have huge development space.

Yet utilize digital raster fringe projection to realize real-time optical three-dimensional measurement and be still faced with many problems and challenge.First, although measuring speed is very fast, because the scene of measuring is dynamic all the time, violate to a certain extent the basic assumption of phase-shift method, caused object edge can produce a large amount of Null Spots.The second, measuring process is easy to be subject to the impact of video camera or projector self-noise and unstable measurement environment, causes measuring error to increase, and produces Null Spot.Final these Null Spots that produce, have reduced the precision of measuring greatly.So in order to improve the precision of real-time three-dimensional optical measurement, the eliminating of Null Spot is very necessary.

Current existing Null Spot method for removing mainly all proposes for non real-time static scene, and during the Null Spot producing in need to processing real-time dynamic scene, the method of using is that the phase diagram to obtaining directly carries out gaussian filtering, although this method filtering partial invalidity point, but also destroyed to a certain extent measurement result simultaneously, reduced accuracy and the precision measured.So the Null Spot method for removing that can be applicable to real-time dynamic scene harmless, system still comparatively lacks.

Summary of the invention

The invention solves while measuring dynamic scene, in measurement result, exist Null Spot to affect the difficult problem of measuring accuracy, and the method can not damage to measurement result itself.

In order to solve the problems of the technologies described above, the present invention proposes automatic identification and the method for removing of dynamic scene Null Spot in a kind of real-time optical three-dimensional measurement, comprises the following steps:

Step 1: utilize projector to determinand surface one group of high frequency sinusoidal grating striped of each projection and one group of low frequency sinusoidal grating striped, two groups of sinusoidal grating stripeds all comprise the sinusoidal grating striped that the phase shift of N width is 2 π n/N, the high frequency sinusoidal grating striped and the low frequency sinusoidal grating striped that use camera acquisition to comprise determinand surface information; In high frequency sinusoidal grating striped and low frequency sinusoidal grating striped, use respectively N step phase shift algorithm to calculate and obtain the determinand surface wrapped high frequency phase value of pixel φ (x corresponding to each measured point, y) and low-frequency phase place value φ ' (x, y), then using double frequency to remove to wrap up algorithm time phase calculates to obtain and removes to wrap up later phase value Φ ₁(x, y); Calculate the phase-modulation degree value B that the high frequency sinusoidal grating striped of same measured point, determinand surface corresponding pixel points comprises simultaneously _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _low(x, y); Wherein (x, y) is camera review pixel coordinate;

Step 2: each pixel is removed to wrap up later phase value Φ ₁(x, y) substitution formula (1), whether judgment formula (1) is set up, if formula (1) is false, corresponding pixel points is Null Spot, is got rid of; If formula (1) is set up, corresponding pixel points is retained,

$E>\sqrt{\frac{{\mathrm{\Σ}}_n^N{(K_n^{\′\′}-K_n^{\′})}^2}{N}}---\left(1\right)$

In formula (1), n value is followed successively by 1,2,3 ... N, total phase shift step number that N is phase shift algorithm, E is the judgment threshold of formula (6), span is between 0 to 1;

In formula (1), intermediate quantity K _n'=cos[Φ ₁(x, y)+2 π n/N];

In formula (1), intermediate quantity

wherein, (x, y) is camera review pixel coordinate, and A (x, y) is the average intensity of camera acquisition image, and B (x, y) is the phase-modulation degree value of camera acquisition image, and $B(x,y)=\frac{2}{N}\sqrt{{\left[{\mathrm{\Σ}}_{n=1}^N{I}_n^c(x,y)\sin (2\mathrm{\πn}/N)\right]}^2+{\left[{\mathrm{\Σ}}_{n=1}^N{I}_n^c(x,y)\cos (2\mathrm{\πn}/N)\right]}^2};$

Step 3: the phase-modulation degree value B that the high frequency sinusoidal grating striped of each pixel is comprised _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _low(x, y) substitution formula (2), whether judgment formula (2) is set up, if formula (2) is false, corresponding pixel points is Null Spot, is got rid of; If formula (2) is set up, corresponding pixel points is retained,

$\frac{\mathrm{abs}[B_{\mathrm{High}}(x,y)-B_{\mathrm{Low}}(x,y)]}{0.5\&times;[B_{\mathrm{High}}(x,y)+B_{\mathrm{Low}}(x,y)]}<\mathrm{\&sigma;}---\left(2\right)$

In formula (2), abs is for asking for signed magnitude arithmetic(al) symbol, and σ is the judgment threshold of formula (2), and span is between 0 to 1;

Step 4: by each pixel (x, y) with and the phase value Φ of right pixel point (x+1, y) ₁(x, y) and Φ ₁(x+1, y) substitution formula (3), whether judgment formula (3) is set up, if formula (3) is false, corresponding pixel points is Null Spot, is got rid of; If formula (3) is set up, corresponding pixel points is retained,

Δ ₁＜Φ ₁(x+1,y)-Φ ₁(x,y)＜Δ ₂ （3）

In formula (3), Δ ₁and Δ ₂be the judgment threshold of formula (3), Δ ₁with Δ ₂span between-π to π;

Step 5: the phase value Φ with Gaussian filter to each pixel ₁(x, y) does gaussian filtering and obtains filtered phase value

by the phase value Φ of each pixel ₁phase value after (x, y) and filtering

substitution formula (4), whether judgment formula (4) is set up, if formula (4) is false, corresponding pixel points is Null Spot, is got rid of; If formula (4) is set up, corresponding pixel points is retained,

$\mathrm{abs}({\mathrm{\&Phi;}}_1(x,y)-\widetilde{\mathrm{\&Phi;}}(x,y))<V---\left(4\right)$

In formula (4), the judgment threshold of V formula (4), span is between 0 to 1.

The present invention compared with prior art, its remarkable advantage is, the present invention utilizes N step phase-shift method and double frequency method is obtained time phase phase shift figure, grating fringe, phase-modulation degree figure and Gaussian filter to scout Null Spot, got rid of efficiently due to object of which movement and Null Spot that unsettled measurement environment has produced, significantly improved the precision of measurement result; And owing to the present invention is based on widely used N step phase shift algorithm, all have a blanket characteristic, portable strong, has very high practical value.

Accompanying drawing explanation

Fig. 1 is automatic identification and the method for removing implementing procedure figure of dynamic scene Null Spot in real-time optical three-dimensional measurement of the present invention.

While measuring the palm of motion in optical three-dimensional measurement when Fig. 2 is, do not use any Null Spot to get rid of algorithm, the three-dimensional measuring result figure of original acquisition.

Fig. 3 is for being used the inventive method step 2 to process the three-dimensional measuring result figure obtaining after Fig. 2.

Fig. 4 is for being used the inventive method step 3 to process the three-dimensional measuring result figure obtaining after Fig. 3.

Fig. 5 is for being used the inventive method step 4 to process the three-dimensional measuring result figure obtaining after Fig. 4.

Fig. 6 is for being used the inventive method step 5 to process the three-dimensional measuring result figure obtaining after Fig. 4.

Embodiment

As shown in Figure 1, automatic identification and the method for removing of dynamic scene Null Spot in real-time optical three-dimensional measurement of the present invention, step is as follows:

Step 1: utilize projector to determinand surface one group of high frequency sinusoidal grating striped of each projection and one group of low frequency sinusoidal grating striped, two groups of sinusoidal grating stripeds all comprise the sinusoidal grating striped that the phase shift of N width is 2 π n/N, the high frequency sinusoidal grating striped and the low frequency sinusoidal grating striped that use camera acquisition to comprise determinand surface information; In high frequency sinusoidal grating striped and low frequency sinusoidal grating striped, use respectively N step phase shift algorithm to calculate and obtain the determinand surface wrapped high frequency phase value of pixel φ (x corresponding to each measured point, y) and low-frequency phase place value φ ' (x, y), then using double frequency to remove to wrap up algorithm time phase calculates to obtain and removes to wrap up later phase value Φ ₁(x, y); Calculate the phase-modulation degree value B that the high frequency sinusoidal grating striped of same measured point, determinand surface corresponding pixel points comprises simultaneously _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _low(x, y).

Described high frequency sinusoidal grating striped is that, when the vertical sinusoidal grating striped of projection, the cycle of sinusoidal grating striped is less than projector lateral resolution; Described low frequency sinusoidal grating striped is that, when the vertical sinusoidal grating striped of projection, the cycle of sinusoidal grating striped equals projector lateral resolution;

The account form of described wrapped high frequency phase value φ (x, y) and low-frequency phase place value φ ' (x, y) enters shown in formula (1) and (2),

$\mathrm{\&phi;}(x,y)={\tan }^{-1}\frac{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^C(x,y)\sin (2\mathrm{\&pi;n}/N)}{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^C(x,y)\cos (2\mathrm{\&pi;n}/N)}---\left(1\right)$

${\mathrm{\&phi;}}^{\&prime;}(x,y)={\tan }^{-1}\frac{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{C^{\&prime;}}(x,y)\sin (2\mathrm{\&pi;n}/N)}{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{C^{\&prime;}}(x,y)\cos (2\mathrm{\&pi;n}/N)}---\left(2\right)$

In formula (1) and (2), (x, y) is camera review pixel coordinate,

for the image intensity of the high frequency sinusoidal grating striped of camera acquisition, for the image intensity of the low frequency sinusoidal grating striped of camera acquisition, n value is followed successively by 1,2,3 ... N, total phase shift step number that N is phase shift algorithm;

Describedly remove to wrap up later phase value Φ ₁the account form of (x, y) as shown in Equation (3),

${\mathrm{\&Phi;}}_1(x,y)=\mathrm{\&phi;}(x,y)+2\mathrm{\&pi;}\&times;\mathrm{Round}\left[\frac{k{\mathrm{\&phi;}}^{\&prime;}(x,y)-\mathrm{\&phi;}(x,y)}{2\mathrm{\&pi;}}\right]---\left(3\right)$

In formula (3), k is the ratio in cycle with the cycle of high frequency sinusoidal grating striped of low frequency sinusoidal grating striped, and Round is for getting nearest integer arithmetic symbol;

The phase-modulation degree value B that described high frequency sinusoidal grating striped comprises _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _lowthe account form of (x, y) as shown in formula (4) and (5),

$B_{\mathrm{High}}(x,y)=\frac{2}{N}\sqrt{{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\sin (2\mathrm{\&pi;n}/N)\right]}^2+{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\cos (2\mathrm{\&pi;n}/N)\right]}^2}---\left(4\right)$

$B_{\mathrm{Low}}(x,y)=\frac{2}{N}\sqrt{{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{c^{\&prime;}}(x,y)\sin (2\mathrm{\&pi;n}/N)\right]}^2+{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{c^{\&prime;}}(x,y)\cos (2\mathrm{\&pi;n}/N)\right]}^2}---\left(5\right)$

Step 2: each pixel is removed to wrap up later phase value Φ ₁(x, y) substitution formula (6), whether judgment formula (6) is set up, if formula (6) is false, corresponding pixel points is Null Spot, is got rid of; If formula (6) is set up, corresponding pixel points is retained,

$E>\sqrt{\frac{{\mathrm{\&Sigma;}}_n^N{(K_n^{\&prime;\&prime;}-K_n^{\&prime;})}^2}{N}}---\left(6\right)$

In formula (6), E is the judgment threshold of formula (6), span generally between 0 to 1,

In formula (6), intermediate quantity K _n'=cos[Φ ₁(x, y)+2 π n/N],

In formula (6), intermediate quantity

wherein, (x, y) is camera review pixel coordinate, and A (x, y) is the average intensity of camera acquisition image, and B (x, y) is the phase-modulation degree value of camera acquisition image, and $B(x,y)=\frac{2}{N}\sqrt{{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\sin (2\mathrm{\&pi;n}/N)\right]}^2+{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\cos (2\mathrm{\&pi;n}/N)\right]}^2}$

Step 3: the phase-modulation degree value B that the high frequency sinusoidal grating striped of each pixel is comprised _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _low(x, y) substitution formula (7), whether judgment formula (7) is set up, if formula (7) is false, corresponding pixel points is Null Spot, is got rid of; If formula (7) is set up, corresponding pixel points is retained,

$\frac{\mathrm{abs}[B_{\mathrm{High}}(x,y)-B_{\mathrm{Low}}(x,y)]}{0.5\&times;[B_{\mathrm{High}}(x,y)+B_{\mathrm{Low}}(x,y)]}<\mathrm{\&sigma;}---\left(7\right)$

In formula (7), abs is for asking for signed magnitude arithmetic(al) symbol, and σ is the judgment threshold of formula (7), span generally between 0 to 1,

Step 4: by each pixel (x, y) with and the phase value Φ of right pixel point (x+1, y) ₁(x, y) and Φ ₁(x+1, y) substitution formula (8), whether judgment formula (8) is set up, if formula (8) is false, corresponding pixel points is Null Spot, is got rid of; If formula (8) is set up, corresponding pixel points is retained,

Δ ₁＜Φ ₁(x+1,y)-Φ ₁(x,y)＜Δ ₂ （8）

In formula (8), Δ ₁and Δ ₂be the judgment threshold of formula (8), Δ ₁with Δ ₂span between-π to π,

Step 5: the phase value Φ with Gaussian filter to each pixel ₁(x, y) does gaussian filtering and obtains filtered phase value by the phase value Φ of each pixel ₁phase value after (x, y) and filtering

substitution formula (9), whether judgment formula (9) is set up, if formula (9) is false, corresponding pixel points is Null Spot, is got rid of; If formula (9) is set up, corresponding pixel points is retained,

$\mathrm{abs}({\mathrm{\&Phi;}}_1(x,y)-\widetilde{\mathrm{\&Phi;}}(x,y))<V---\left(9\right)$

In formula (9), the judgment threshold of V formula (9), span is generally between 0 to 1.

Embodiment

While first adopting, optical three-dimensional measuring method is measured the palm of motion, and measuring system comprises DLP projector (ACER X1161PA), industrial CCD (AVT GE680), FPGA development board and a computing machine.During measurement, palm swings up and down with the speed of 0.6 meter per second.When not adopting any Null Spot removal method, measurement result is shown in Fig. 2.Concrete measuring method list of references < < Novel method for structured light system > >, author Song Zhang and the Peisen S.Huang using.

From Fig. 2, can find at the edge of finger contours, there are the lines of a lot of projections, what these lines represented is exactly the Null Spot producing in measuring process.As shown in Figure 3, in the present embodiment step 2, E value is 0.234 to the three-dimensional measuring result obtaining after use the inventive method step 2 processing Fig. 2, and the quantity of Null Spot reduces as can be seen from Figure 3, such as that the longest line that represents Null Spot disappears.As shown in Figure 4, in the present embodiment step 3, σ value is 0.25 to the three-dimensional measuring result obtaining after use the inventive method step 3 processing Fig. 3.The three-dimensional measuring result of using the inventive method step 4 to process to obtain after Fig. 4 as shown in Figure 5, Δ in the present embodiment step 4 ₁be set as

Δ ₂be set as

as can be seen from Figure 4 and Figure 5, the quantity of Null Spot is reducing.Finally, the three-dimensional measuring result obtaining after use the inventive method step 5 processing Fig. 5 as shown in Figure 6, the Gaussian filter that adopt in the present embodiment step 5 and be of a size of 3 * 3, standard deviation is 0.3, V value 0.14, the Null Spot at finger contours edge is all successfully got rid of as can be seen from Figure 6.

Claims (5)

1. automatic identification and the method for removing of dynamic scene Null Spot in real-time optical three-dimensional measurement, is characterized in that, comprises the following steps:

Step 1: utilize projector to determinand surface one group of high frequency sinusoidal grating striped of each projection and one group of low frequency sinusoidal grating striped, two groups of sinusoidal grating stripeds all comprise the sinusoidal grating striped that the phase shift of N width is 2 π n/N, the high frequency sinusoidal grating striped and the low frequency sinusoidal grating striped that use camera acquisition to comprise determinand surface information; In high frequency sinusoidal grating striped and low frequency sinusoidal grating striped, use respectively N step phase shift algorithm to calculate and obtain the determinand surface wrapped high frequency phase value of pixel φ (x corresponding to each measured point, y) and low-frequency phase place value φ ' (x, y), then using double frequency to remove to wrap up algorithm time phase calculates to obtain and removes to wrap up later phase value Φ ₁(x, y); Calculate the phase-modulation degree value B that the high frequency sinusoidal grating striped of same measured point, determinand surface corresponding pixel points comprises simultaneously _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _low(x, y); Wherein (x, y) is camera review pixel coordinate;

Step 2: each pixel is removed to wrap up later phase value Φ ₁(x, y) substitution formula (1), whether judgment formula (1) is set up, if formula (1) is false, corresponding pixel points is Null Spot, is got rid of; If formula (1) is set up, corresponding pixel points is retained,

$E>\sqrt{\frac{{\mathrm{\&Sigma;}}_n^N{(K_n^{\&prime;\&prime;}-K_n^{\&prime;})}^2}{N}}---\left(1\right)$

In formula (1), n value is followed successively by 1,2,3 ... N, total phase shift step number that N is phase shift algorithm, E is the judgment threshold of formula (6), span is between 0 to 1;

In formula (1), intermediate quantity K _n'=cos[Φ ₁(x, y)+2 π n/N];

In formula (1), intermediate quantity

wherein, (x, y) is camera review pixel coordinate, and A (x, y) is the average intensity of camera acquisition image, and B (x, y) is the phase-modulation degree value of camera acquisition image, and $B(x,y)=\frac{2}{N}\sqrt{{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\sin (2\mathrm{\&pi;n}/N)\right]}^2+{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\cos (2\mathrm{\&pi;n}/N)\right]}^2};$

Step 3: the phase-modulation degree value B that the high frequency sinusoidal grating striped of each pixel is comprised _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _low(x, y) substitution formula (2), whether judgment formula (2) is set up, if formula (2) is false, corresponding pixel points is Null Spot, is got rid of; If formula (2) is set up, corresponding pixel points is retained,

$\frac{\mathrm{abs}[B_{\mathrm{High}}(x,y)-B_{\mathrm{Low}}(x,y)]}{0.5\&times;[B_{\mathrm{High}}(x,y)+B_{\mathrm{Low}}(x,y)]}<\mathrm{\&sigma;}---\left(2\right)$

In formula (2), abs is for asking for signed magnitude arithmetic(al) symbol, and σ is the judgment threshold of formula (2), and span is between 0 to 1;

Step 4: by each pixel (x, y) with and the phase value Φ of right pixel point (x+1, y) ₁(x, y) and Φ ₁(x+1, y) substitution formula (3), whether judgment formula (3) is set up, if formula (3) is false, corresponding pixel points is Null Spot, is got rid of; If formula (3) is set up, corresponding pixel points is retained,

Δ ₁＜Φ ₁(x+1,y)-Φ ₁(x,y)＜Δ ₂ （3）

In formula (3), Δ ₁and Δ ₂be the judgment threshold of formula (3), Δ ₁with Δ ₂span between-π to π;

Step 5: the phase value Φ with Gaussian filter to each pixel ₁(x, y) does gaussian filtering and obtains filtered phase value

by the phase value Φ of each pixel ₁phase value after (x, y) and filtering substitution formula (4), whether judgment formula (4) is set up, if formula (4) is false, corresponding pixel points is Null Spot, is got rid of; If formula (4) is set up, corresponding pixel points is retained,

$\mathrm{abs}({\mathrm{\&Phi;}}_1(x,y)-\widetilde{\mathrm{\&Phi;}}(x,y))<V---\left(4\right)$

In formula (4), the judgment threshold of V formula (4), span is between 0 to 1.

2. automatic identification and the method for removing of dynamic scene Null Spot in real-time optical three-dimensional measurement as claimed in claim 1, it is characterized in that, described high frequency sinusoidal grating striped is that, when the vertical sinusoidal grating striped of projection, the cycle of sinusoidal grating striped is less than projector lateral resolution; Described low frequency sinusoidal grating striped is that, when the vertical sinusoidal grating striped of projection, the cycle of sinusoidal grating striped equals projector lateral resolution.

3. automatic identification and the method for removing of dynamic scene Null Spot in real-time optical three-dimensional measurement as claimed in claim 1, it is characterized in that described wrapped high frequency phase value φ (x, y) and low-frequency phase place value φ ' (x, y) account form enters shown in formula (5) and (6)

$\mathrm{\&phi;}(x,y)={\tan }^{-1}\frac{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^C(x,y)\sin (2\mathrm{\&pi;n}/N)}{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^C(x,y)\cos (2\mathrm{\&pi;n}/N)}---\left(5\right)$

${\mathrm{\&phi;}}^{\&prime;}(x,y)={\tan }^{-1}\frac{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{C^{\&prime;}}(x,y)\sin (2\mathrm{\&pi;n}/N)}{{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{C^{\&prime;}}(x,y)\cos (2\mathrm{\&pi;n}/N)}---\left(6\right)$

In formula (5) and (6), (x, y) is camera review pixel coordinate, for the image intensity of the high frequency sinusoidal grating striped of camera acquisition,

for the image intensity of the low frequency sinusoidal grating striped of camera acquisition, n value is followed successively by 1,2,3 ... N, total phase shift step number that N is phase shift algorithm.

4. automatic identification and the method for removing of dynamic scene Null Spot in real-time optical three-dimensional measurement as claimed in claim 1, is characterized in that, described in remove to wrap up later phase value Φ ₁the account form of (x, y) as shown in Equation (7),

${\mathrm{\&Phi;}}_1(x,y)=\mathrm{\&phi;}(x,y)+2\mathrm{\&pi;}\&times;\mathrm{Round}\left[\frac{k{\mathrm{\&phi;}}^{\&prime;}(x,y)-\mathrm{\&phi;}(x,y)}{2\mathrm{\&pi;}}\right]---\left(7\right)$

In formula (7), k is the ratio in cycle with the cycle of high frequency sinusoidal grating striped of low frequency sinusoidal grating striped, and Round is for getting nearest integer arithmetic symbol.

5. automatic identification and the method for removing of dynamic scene Null Spot in real-time optical three-dimensional measurement as claimed in claim 1, is characterized in that, the phase-modulation degree value B that described high frequency sinusoidal grating striped comprises _highthe phase-modulation degree value B that (x, y) and low frequency sinusoidal grating striped comprise _lowthe account form of (x, y) as shown in formula (8) and (9),

$B_{\mathrm{High}}(x,y)=\frac{2}{N}\sqrt{{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\sin (2\mathrm{\&pi;n}/N)\right]}^2+{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^c(x,y)\cos (2\mathrm{\&pi;n}/N)\right]}^2}---\left(8\right)$

$B_{\mathrm{Low}}(x,y)=\frac{2}{N}\sqrt{{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{c^{\&prime;}}(x,y)\sin (2\mathrm{\&pi;n}/N)\right]}^2+{\left[{\mathrm{\&Sigma;}}_{n=1}^N{I}_n^{c^{\&prime;}}(x,y)\cos (2\mathrm{\&pi;n}/N)\right]}^2}---\left(9\right).$

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