CN111445400A - Method and device for removing absolute phase noise in presence of projection blind area and storage medium - Google Patents
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Abstract
The invention provides a method for removing absolute phase noise in the presence of a projection blind area, which comprises the following steps: acquiring absolute phase value data from the fringe pattern; acquiring an absolute phase straight line according to the absolute phase data, and dividing a corresponding effective area; determining a reference absolute phase line; acquiring a first difference value through an absolute phase straight line and a reference absolute phase straight line of the same abscissa, and acquiring a first average value; acquiring a second difference value through the absolute phase value data acquired in the effective area and a reference absolute phase straight line of the same abscissa, and comparing the second difference value with the first average value to determine a reference difference value; presetting a threshold range, comparing the reference difference value with a second difference value, and dividing noise points and non-noise points; and after eliminating the noise points, correcting the absolute phase straight line to obtain corrected absolute phase value data, and reconstructing the three-dimensional object. The denoising method disclosed by the invention is low in computational complexity and high in denoising efficiency, and can improve the accuracy of absolute phase and the reconstruction precision of the three-dimensional object.
Description
Technical Field
The invention belongs to the field of three-dimensional imaging, and particularly relates to a method and a device for removing absolute phase noise in the presence of a projection blind area, and a storage medium.
Background
The three-dimensional measuring equipment based on the structured light stripe projection has the characteristics of high measuring precision, good real-time performance, non-contact property and the like, and is widely applied to different fields of life and industry. The structured light fringe projection is to project a designed fringe pattern onto a three-dimensional object, a deformed fringe pattern can be obtained after projection, then a phase shift algorithm is utilized to calculate the deformed fringe pattern so as to obtain a wrapping phase, and then the wrapping phase is recovered so as to obtain an absolute phase, wherein the reconstruction precision of the three-dimensional object is influenced by the precision of the absolute phase. Due to various factors such as errors of measuring equipment, interference of external environment, limitation of algorithm and the like, noise is inevitably generated in the process of acquiring the absolute phase, and the reconstruction precision of the three-dimensional object is influenced by the noise. However, most of the current absolute phase noise removing methods cannot filter a large number of noise points, and have high computational complexity and large computational complexity.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a method for removing absolute phase noise with a projection blind area, which can reduce the calculation complexity, improve the noise removal efficiency and improve the reconstruction precision of a three-dimensional object.
According to an embodiment of the first aspect of the invention, a method for removing absolute phase noise in the presence of a dead projection zone comprises the following steps: acquiring absolute phase value data from the fringe pattern; acquiring absolute phase straight lines according to the absolute phase data, and dividing corresponding effective areas according to each absolute phase straight line; determining a reference absolute phase line to which each of said absolute phase lines is respectively compared; acquiring a first difference value through the absolute phase value of the absolute phase straight line of the same abscissa and a reference absolute phase value of the reference absolute phase straight line, and acquiring a first average value through the first difference value; obtaining a second difference value through the absolute phase value data obtained in the corresponding effective area and a reference absolute phase value of a reference absolute phase straight line of the same abscissa, and comparing the second difference value with the first average value to determine a reference difference value; presetting a threshold range, comparing the reference difference value with a second difference value, and dividing noise points and non-noise points of the absolute phase value data; and after the noise points are eliminated, correcting the absolute phase straight line to obtain corrected absolute phase value data, and reconstructing the three-dimensional object.
The method for removing absolute phase noise with a projection blind area according to the embodiment of the invention at least has the following beneficial effects: according to the method, the absolute phase value data is judged through the absolute phase straight line and the reference absolute phase straight line through the difference value operation, the noise points and the non-noise points of the absolute phase value data are screened out, the noise points of the absolute phase value are effectively eliminated, the calculation complexity is low, the operation is simple, the denoising efficiency is high, meanwhile, the absolute phase value of the non-noise points is corrected, the accuracy of the absolute phase value can be improved, the noise influence is avoided, and the reconstruction precision of the three-dimensional object can be improved.
According to some embodiments of the invention, acquiring absolute phase value data from the fringe pattern comprises the steps of: acquiring wrapping phase data from the fringe pattern; recovering the wrapped phase data into the absolute phase data.
According to some embodiments of the present invention, "acquiring absolute phase lines from absolute phase data and dividing an effective area according to each absolute phase line" comprises the steps of: segmenting and labeling the absolute phase value data; obtaining the segmented absolute phase straight line after segmentation; and dividing the corresponding effective area according to each absolute phase straight line.
According to some embodiments of the invention, segmenting and labeling absolute phase value data comprises the steps of: detecting valid data and invalid data in the absolute phase data; respectively marking valid data and invalid data; the absolute phase data is divided according to the valid data and the invalid data.
According to some embodiments of the invention, the valid data is an absolute phase value other than 0 and the invalid data is an absolute phase value of 0.
According to some embodiments of the invention, "determining a reference absolute phase line to which each of said absolute phase lines is compared, respectively" comprises the steps of: and determining a reference absolute phase straight line according to the number of effective data in the absolute phase data and through straight line detection.
According to some embodiments of the invention, the line detection uses hall transform line detection.
According to some embodiments of the present invention, after the noise points are eliminated, the absolute phase straight line is corrected to obtain a correct absolute phase value, and a three-dimensional object is reconstructed, the method includes the following steps: acquiring a third difference value through the absolute phase value data of the non-noise point in the effective area and the reference absolute phase value of the reference absolute phase straight line of the same abscissa, acquiring a second average value through the third difference value, and setting the second average value as a reference distance value; correcting an absolute phase straight line according to the reference distance value and the reference absolute phase straight line; and acquiring a correct absolute phase value through the corrected absolute phase straight line, and reconstructing the three-dimensional object.
A device for removing absolute phase noise in the presence of a dead zone in projection according to an embodiment of a second aspect of the present invention is characterized by comprising: at least one processor and a memory communicatively coupled to the processor; the memory stores instructions executable by the at least one processor to enable the processor to perform the method for removing absolute phase noise in the presence of shadow of projection as described above.
A computer-readable storage medium according to an embodiment of the third aspect of the present invention is characterized in that the computer-readable storage medium stores computer-executable instructions for causing a computer to execute the method for removing absolute phase noise in the presence of a dead zone of projection as described above.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
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The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flow chart of the method for removing absolute phase noise in the presence of a dead zone of projection according to the present invention.
Fig. 2 is a flow chart of the present invention for obtaining absolute phase value data from a fringe pattern.
FIG. 3 is a schematic diagram of a deformed fringe pattern according to the present invention.
FIG. 4 is a graphical illustration of the wrapped phase without a shadow region according to the present invention.
FIG. 5 is a graphical illustration of the absolute phase without dead zones for projection according to the present invention.
Fig. 6 is a flowchart of acquiring absolute phase lines according to absolute phase data and dividing corresponding effective areas according to each absolute phase line according to the present invention.
Fig. 7 is a flow chart of absolute phase value data segmentation and labeling of the present invention.
FIG. 8 is a schematic diagram of absolute phase with noise points and dead projection zones according to the present invention.
FIG. 9 is a schematic diagram of absolute phase with dead projection zone and noise point removed according to the present invention.
FIG. 10 is a schematic diagram of the absolute phase of a three-dimensional object with noise points and a dead projection zone according to the present invention.
Fig. 11 is a schematic diagram of the absolute phase of the three-dimensional object with the noise points removed and the dead projection zone.
FIG. 12 is a flow chart of the modified absolute phase line equation of the present invention.
Fig. 13 is a schematic structural diagram of the device for removing absolute phase noise with dead projection zone according to the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, outer, inner, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
In order to more clearly understand the technical features, objects and effects of the present invention, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1, the present invention provides a method for removing absolute phase noise in the presence of a dead projection zone, comprising the following steps:
step S100, acquiring absolute phase value data from the fringe pattern;
step S200, acquiring absolute phase straight lines according to absolute phase data, and dividing corresponding effective areas according to each absolute phase straight line;
step S300, determining a reference absolute phase straight line which is respectively compared with each absolute phase straight line;
step S400, obtaining a first difference value through the absolute phase value of the absolute phase straight line of the same abscissa and the reference absolute phase value of the reference absolute phase straight line, and obtaining a first average value through the first difference value;
step S500, acquiring a second difference value through the absolute phase value data acquired in the corresponding effective area and a reference absolute phase value of a reference absolute phase straight line of the same abscissa, and comparing the second difference value with the first average value to determine a reference difference value;
step S600, presetting a threshold range, comparing the reference difference value with a second difference value, and dividing noise points and non-noise points of absolute phase value data;
and S700, after the noise points are eliminated, correcting the absolute phase straight line to obtain corrected absolute phase value data, and reconstructing the three-dimensional object.
According to the method, the absolute phase value data is judged through the absolute phase straight line and the reference absolute phase straight line through the difference value operation, the noise points and the non-noise points of the absolute phase value data are screened out, the noise points of the absolute phase value are effectively eliminated, the calculation complexity is low, the operation is simple, the denoising efficiency is high, meanwhile, the absolute phase value of the non-noise points is corrected, the accuracy of the absolute phase value can be improved, the noise influence is avoided, and the reconstruction precision of the three-dimensional object can be improved.
Referring to fig. 2, in some embodiments of the present invention, step S100 obtains absolute phase value data from the fringe pattern. Specifically, the method further comprises the following steps:
step S110, acquiring wrapping phase data from the fringe pattern;
step S120, the wrapped phase data is restored to absolute phase data.
Wherein, the fringe pattern is a pattern with amplitude range of longitudinal sinusoidal variation of 0-1 and is composed of a plurality of cycles. In the process of reconstructing the three-dimensional object, a plurality of fringe patterns are adopted, and the fringe patterns are two sinusoidal variation patterns with different wavelengths and different phase shifts. Referring to fig. 3, in this embodiment, the three-dimensional object is a stepped step model, and when the fringe pattern is projected onto the step model, a deformed fringe pattern as shown in fig. 3 is obtained, where the dead zone of projection is shown by an arrow a in fig. 3. Calculating the deformed fringe pattern through a phase shift algorithm to obtain a wrapping phase; and then, the wrapped phase data is unwrapped by using a dual-wavelength phase unwrapping algorithm to recover the absolute phase data. The three-dimensional object can be reconstructed from the absolute phase data.
Specifically, the acquisition process of the wrapped phase value data is as follows: for example, 6 fringe patterns with different phase differences under the same wavelength are adopted, then the fringe patterns are projected onto a three-dimensional object, and the obtained six deformed fringe patterns are used for solving through a phase shift algorithm.
The projected fringe pattern sine variation law is as follows:
the change rule of the points corresponding to the deformed fringe pattern is as follows:
the two equations are substituted to obtain the wrapped phase value:
wherein, IpiAnd IciIs a pixel value, IcIs the average gray value, I'cIs a modulation value of phip(xpP) and phic(xcAnd c) is a phase value. More specifically, IpiIs the pixel value of the fringe pattern, and IciIs the pixel value of the deformed fringe pattern.
The wrapped phase value can be calculated according to the algorithm. After the above calculation, a graph of the parcel phase can be obtained as shown in fig. 4, where the ordinate is the parcel phase value and the abscissa is the row coordinate in fig. 4. In fig. 4, which is a schematic diagram of the wrapping phase without the dead zone of projection, the graph shown in fig. 4 can be obtained through the above calculation, and the graph of the wrapping phase is jagged. When the dead zone exists, the graph of the wrapping phase obtained by the calculation is also jagged, but the graph of the wrapping phase has segments.
After the wrapped phase value is calculated, the wrapped phase value needs to be unwrapped to restore the wrapped phase value to an absolute phase value.
Specifically, the acquisition process of the absolute phase value data is: the solution is carried out by a table look-up through a dual-wavelength phase unwrapping algorithm, namely, by using the difference value of wrapping phases of two wavelengths.
Solving for the absolute phase data by the following equation:
wherein, T1，T2At two wavelengths, k1，k2I.e. the K value of the absolute phase of the corresponding wavelength (i.e. the fringe order). Phi is ac1(cC) and phic2(xcAnd c) wrapped phase values for different wavelengths.
For example, in the present embodiment, T1，T2Taking 23 and 47 as examples, according to the above formula, two points with the same coordinate as the wrapped phase value are subtracted, the difference is rounded and matched with the third column of data in table 1, and the K value of the corresponding wavelength is found.
TABLE 1
The absolute phase value data for each column in the image can be obtained by the algorithm described above. After the above calculation, a graph of the absolute phase can be obtained as shown in fig. 5, where the ordinate is the absolute phase value and the abscissa is the row coordinate in fig. 5. Fig. 5 is a schematic diagram showing an absolute phase without a dead zone in projection, and the graph shown in fig. 5 can be obtained by the above calculation, and the graph of the absolute phase is linear as a whole. When there is a dead zone, the absolute phase pattern obtained by the above calculation is also linear, but the absolute phase pattern has segments, and the absolute phase pattern having a dead zone is shown in fig. 8 and 9.
In the present embodiment, "column" herein refers to a column of data that matches the sinusoidal variation direction of the fringe pattern, and since the captured fringes vary vertically, in the present embodiment, "column" can also be understood as a column of pixel points in the vertical direction of the image. While a "row" in a row coordinate corresponds to a "column," it is understood that each row in the image, i.e., the row coordinate, is represented as a change in the number of rows in the image.
Referring to fig. 6, in some embodiments of the present invention, step S200 is performed to obtain absolute phase lines according to absolute phase data, and divide corresponding effective areas according to each absolute phase line. Specifically, the method further comprises the following steps:
step S210, dividing and marking absolute phase value data;
step S220, obtaining segmented absolute phase straight lines after segmentation;
step S230, dividing the corresponding effective area according to each absolute phase line.
Referring to fig. 7, in some embodiments of the present invention, step S210 segments and labels the absolute phase value data. Specifically, the method further comprises the following steps:
step S211 of detecting valid data and invalid data in the absolute phase data;
step S212, marking valid data and invalid data respectively;
in step S213, the absolute phase data is divided based on the valid data and the invalid data.
In some embodiments of the present invention, the valid data is an absolute phase value other than 0, and the invalid data is an absolute phase value of 0.
More specifically, for example, assume that o is valid data and x is invalid data. The absolute phase data of a certain column of the image is ooxxooxoo, the absolute phase of the data of the column is divided and marked as 1100220033 by detecting invalid data x, the invalid data is marked as 0, the valid data is marked as 1,2 and 3 … … (which can be used for representing the segmentation situation of the absolute phase straight line of the column), and the absolute phase straight line of the column is divided into three segments in the example.
The dead projection zone occurs because the camera, the projection and the placement position of the three-dimensional object can have a part which cannot be covered by the fringe pattern, but the part which cannot be covered by the fringe pattern is shot by the camera, so that the part which cannot be covered by the fringe pattern is called the dead projection zone, and due to the dead projection zone, the absolute phase data in the same column can be segmented. Therefore, data division and marking are required, after division, the absolute phase value data of the same column presents a segmented straight line shape, i.e., an absolute phase straight line, the absolute phase value data of the non-noise point is located on the absolute phase straight line, and the absolute phase value data of the noise point is located outside the absolute phase straight line. The slope of the absolute phase straight line of each column is the same, and the intercept is different.
In the example of the division and labeling of absolute phase value data presented above, the absolute phase line of the column is divided into three segments, whereby the absolute phase line divides the column into three valid regions, valid data of absolute phases fall within the three valid regions, respectively, while valid absolute phase data of non-noise points lie on the corresponding absolute phase line, while valid absolute phase data of noise points lie outside the corresponding absolute phase line. The division of the effective areas of the other columns in the image is as above, after the number of absolute phase straight lines of the column is determined according to the division and the marking of the effective data and the invalid data, the effective areas corresponding to the absolute phase straight lines are divided, and the absolute phase value data acquired from the fringe pattern falls into the corresponding effective areas. It is noted that in the present invention, the "effective region" is proposed to divide the data so as to make the subsequent calculation of removing noise points more clear and intuitive.
Referring to fig. 1, 6 and 7, in step S300, a reference absolute phase line is determined to be compared with each absolute phase line. Specifically, the method comprises the following steps: a reference absolute phase straight line is determined by straight line detection based on the number of valid data in the absolute phase value data.
More specifically, the process of determining the reference absolute phase line is as follows: the column with the most effective data in the absolute phase value data is searched in each column, the column with the most effective absolute phase value data is selected, the probability of extracting the data with the maximum data continuity is high, the accuracy of a noise point can be improved, and therefore the accuracy of the absolute phase is improved. After a column with the most effective absolute phase value data is screened out, the longest absolute phase straight line in the column is subjected to straight line detection, and end point coordinates (x) at two sides of the longest absolute phase straight line are detected1,y1) And (x)2,y2) The linear equation is solved through two end points,
a reference absolute phase linear equation y can be obtainedn＝k×xn+ b, wherein ynIs a reference phase value, xnIs the row coordinate corresponding to the reference phase value. Accordingly, a reference absolute phase line is determined, and a reference absolute phase line equation is obtained.
Since the slopes of the absolute phase lines are the same and the intercepts are different, the absolute phase line equation can be set as: y ismn＝k×xn+bmWherein y ismnIs the absolute phase value of the segment, xnThe slope k of the absolute phase line is the same as the slope k of the reference absolute phase line, and the intercepts are different, and the intercept b is the same as the intercept k of the reference absolute phase line for the row coordinate corresponding to the reference phase valuemIs equal to the wrapped phase value phi and the fringeSum of the order K values.
In some embodiments of the present invention, the line detection is performed by using a hall transform line detection, which is capable of detecting all points on a line, and thus, a column with the most absolute phase data can be detected by using the hall transform line detection, and end point coordinates of both ends of the longest line can be detected.
Referring to fig. 1, in step S400, a first difference is obtained by the absolute phase value of the absolute phase line on the same abscissa and the reference absolute phase value of the reference absolute phase line, and a first average value is obtained by the first difference. The method specifically comprises the following steps: firstly, a section of absolute phase straight line in a certain column is selected, the section of absolute phase straight line corresponds to an effective area, and the absolute phase straight line is processed through an absolute phase straight line equation ymn＝k×xn+bmAnd reference absolute phase linear equation yn＝k×xn+ b calculating the first difference corresponding to the abscissa, i.e. the first difference is dn＝ymn-yn(n is 1,2,3 … …) and a first average value is taken of the first difference, i.e. the first average value is dmean＝(d1+d2+…+dn) And/s, wherein s is the number of difference values, and the number of s is also the same as the number of valid data of the absolute phase value in the valid area.
Referring to fig. 1, in step S500, a second difference value is obtained by using the absolute phase value data obtained in the corresponding effective region and the reference absolute phase value of the reference absolute phase line of the same abscissa, and the second difference value is compared with the first average value to determine a reference differenceThe value is obtained. The method specifically comprises the following steps: in the effective region corresponding to the absolute phase straight line selected in step S400, there are a plurality of effective absolute phase value data, and the obtained absolute phase value data in the effective region and the reference absolute phase value y of the reference absolute phase straight line of the same abscissa are comparednMaking a difference value which is a second difference value RnEvery second difference RnAnd a first average value dmeanCompared from the second difference RnFind the closest first average value dmeanSecond difference value RnAnd by the second difference RnAs a reference difference. Since the number of absolute phase value data of the non-noise point is generally much larger than that of the noise point, the first average value d is obtainedmeanCan be regarded as the difference between the absolute phase value of a non-noise point and the reference absolute phase value, and then the closest first average value d is foundmeanSecond difference value RnAs the reference difference, the absolute phase value data corresponding to the reference difference may be regarded as non-noise data.
Referring to fig. 1, in step S600, a threshold range is preset, the reference difference is compared with the second difference, and the noise point and the non-noise point of the absolute phase value data are divided. Assuming that the second difference comprises R1，R2，R3，R4，R5Wherein the closest first average value dmeanA second difference of R3Then the second difference is R3Set as the reference difference. The reference difference value is compared with the second difference value, and a noise point and a non-noise point of the absolute phase value data are divided according to a preset threshold range. In this embodiment, the absolute phase value data corresponding to the second difference value whose threshold range is such that the absolute value of the difference between the reference difference value and the second difference value is smaller than 1 is a non-noise point, and the absolute phase value data corresponding to the second difference value whose threshold range is such that the absolute value of the difference between the reference difference value and the second difference value is larger than 1 is a noise point. For example, | R1-3|<1, i.e. the second difference R1The corresponding absolute phase value data is a non-noise point; | R4-3|>1, i.e. the second difference R4Corresponding absolute phaseThe value data is a noise point. Therefore, the absolute phase value data of the acquired absolute phase value data can be divided into which the noise points are and which are non-noise points, and the absolute phase value data of the noise points are removed after the division. The method for removing the absolute phase noise of the projection blind area separately compares the absolute phase straight line of each segment with a reference absolute phase straight line, divides the noise point and the non-noise point of the absolute phase straight line of each segment, and corrects the absolute phase straight line of each segment.
Referring to fig. 8 and 9, wherein fig. 8 is a diagram of a certain column of absolute phases before denoising, it can be seen that due to the existence of a shadow projection zone, the absolute phase straight line is segmented, wherein the slopes of the absolute phase straight lines are the same and the intercepts are different, meanwhile, the absolute phase value data of the noise point is shown on the graph, and one continuous straight line shown in fig. 8 is a reference absolute phase straight line. Fig. 9 is a schematic diagram of the absolute phase of fig. 8 after removing noise by the method for removing absolute phase noise with dead projection zone according to the present invention, and similarly, a continuous straight line shown in fig. 9 is a reference absolute phase straight line. As can be seen from the denoising results shown in fig. 8 and 9, the method for removing absolute phase noise in the presence of a projection blind area of the present invention can effectively remove noise points, improve the accuracy of absolute phase value data, and then improve the precision of three-dimensional reconstruction.
Referring to fig. 10 and 11, in this embodiment, taking a staircase model as an example, fig. 10 is an absolute phase image of a whole three-dimensional object before denoising, where the gray values of some pixel points are different from the gray values of the pixel points near the pixel points under the condition of noise, and fig. 11 is an absolute phase image of a whole three-dimensional object after denoising, where the gray values of the pixel points are the same as the gray values of the pixel points near the pixel points after denoising, that is, noise is effectively removed after the method for removing absolute phase noise by using a shadow area.
Referring to fig. 12, in some embodiments of the invention, in step S700, after the noise points are eliminated, the absolute phase straight line is corrected to obtain a correct absolute phase value, and the three-dimensional object is reconstructed. Specifically, the method comprises the following steps:
step S710, obtaining a third difference value through the absolute phase value data of the non-noise point in the effective area and the reference absolute phase value of the reference absolute phase straight line of the same abscissa, obtaining a second average value through the third difference value, and setting the second average value as a reference distance value;
step S720, correcting the absolute phase straight line according to the reference distance value and the reference absolute phase straight line;
and step S730, acquiring a correct absolute phase value through the corrected absolute phase straight line, and reconstructing the three-dimensional object.
More specifically, after the absolute phase value data of the noise point in the effective region is eliminated, the third difference S between the absolute phase value data of the remaining non-noise point and the reference absolute phase value of the reference absolute phase straight line of the same abscissa is calculatednAnd calculating a second average value of the third difference value, i.e. a second average value dc＝(S1+S2+…+Sn) And/m, wherein m is the number of absolute phase value data of the non-noise point. Setting the second average value as dcCorrecting the absolute phase straight line by the reference distance value and the reference absolute phase straight line for the reference distance value, and calculating the intercept b of the corrected absolute phase straight linem'，bm'＝b+dcWhere b is the intercept of the reference absolute phase line, dcIs a reference distance value; the corrected absolute phase linear equation is ymn'＝k×xn+bmAnd finally, the correct absolute phase value data is recalculated by the corrected absolute phase linear equation.
The reference distance value d is taken because the absolute phase value has a certain error in the presence of noise beforecCorrecting the absolute phase straight line to obtain a reference distance value dcThe average value of the difference value between the non-noise absolute phase of the section of the row and the reference phase value corresponding to the abscissa is used, the average value can enable the difference value to be closer to a correct value, and the accuracy of absolute phase straight line correction can be improved.
The absolute phase obtained in the process is the absolute phase with noise, the method for removing the absolute phase noise by the existence of the projection blind area is required to remove noise before the three-dimensional object is reconstructed, the absolute phase is corrected after the noise is removed to obtain the correct absolute phase, and then the three-dimensional object is reconstructed by the corrected absolute phase value data, so that the accuracy of the three-dimensional object reconstruction can be effectively improved.
Referring to fig. 13, an embodiment of the present invention further provides a device for removing absolute phase noise with a shadow area, where the device for removing absolute phase noise with a shadow area can be any type of intelligent terminal, such as a mobile phone, a tablet computer, a personal computer, and the like.
Further, the apparatus for removing absolute phase noise in the presence of a dead zone of projection includes: one or more processors and memory for communicative coupling with the processors. In which one processor is taken as an example in fig. 13. The processor and memory may be connected by a bus or other means, with fig. 13 taking the example of a connection by a bus.
The memory, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs and non-transitory computer executable programs, such as program instructions corresponding to the apparatus for removing absolute phase noise by dead zone projection. The processor implements the above method for removing absolute phase noise in the presence of dead zones by running a non-transitory software program and instructions stored in the memory.
The memory may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area can store the related data of the method for removing absolute phase noise in the dead projection area, and the like. Further, the memory may include high speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory optionally includes memory remotely located from the processor, and the remote memory may be connected to the shadow presence elimination absolute phase noise device via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
In a third aspect of the present invention, a computer-readable storage medium is provided, which stores computer-executable instructions, which when executed by one or more processors, for example, by a processor, cause the one or more processors to perform the above method for removing absolute phase noise in presence of dead zones of projection.
The above-described embodiments of the apparatus are merely illustrative, wherein the units illustrated as separate components may or may not be physically separate, i.e. may be located in one place, or may also be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
One of ordinary skill in the art will appreciate that all or some of the steps, systems, and methods disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Claims (10)
1. A method for removing absolute phase noise in the presence of a projection blind area is characterized by comprising the following steps:
acquiring absolute phase value data from the fringe pattern;
acquiring absolute phase straight lines according to the absolute phase data, and dividing corresponding effective areas according to each absolute phase straight line;
determining a reference absolute phase line to which each of said absolute phase lines is respectively compared;
acquiring a first difference value through the absolute phase value of the absolute phase straight line of the same abscissa and a reference absolute phase value of the reference absolute phase straight line, and acquiring a first average value through the first difference value;
acquiring a second difference value through the absolute phase value data acquired in the corresponding effective area and a reference absolute phase value of a reference absolute phase straight line of the same abscissa, and comparing the second difference value with the first average value to determine a reference difference value;
presetting a threshold range, comparing the reference difference value with a second difference value, and dividing noise points and non-noise points of the absolute phase value data;
and after the noise points are eliminated, correcting the absolute phase straight line to obtain corrected absolute phase value data, and reconstructing the three-dimensional object.
2. The method for removing absolute phase noise in the presence of dead zones of projection according to claim 1, wherein the step of obtaining absolute phase value data from the fringe pattern comprises the steps of:
acquiring wrapping phase data from the fringe pattern;
recovering the wrapped phase data into the absolute phase data.
3. The method for removing absolute phase noise in the presence of dead zones of projection according to claim 1, wherein the step of obtaining absolute phase lines from the absolute phase data and dividing the effective area according to each absolute phase line comprises the steps of:
segmenting and labeling the absolute phase value data;
obtaining the segmented absolute phase straight line after segmentation;
and dividing the corresponding effective area according to each absolute phase straight line.
4. The method for removing absolute phase noise in the presence of a dead zone of projection according to claim 3, wherein the step of segmenting and labeling the absolute phase value data comprises the steps of:
detecting valid data and invalid data in the absolute phase data;
respectively marking valid data and invalid data;
the absolute phase data is divided according to the valid data and the invalid data.
5. The method as claimed in claim 4, wherein the valid data is an absolute phase value other than 0, and the invalid data is an absolute phase value of 0.
6. The method for removing absolute phase noise in the presence of dead zone projection according to claim 1, wherein determining the reference absolute phase line to be compared with each of the absolute phase lines respectively comprises the steps of: a reference absolute phase straight line is determined by straight line detection based on the number of valid data in the absolute phase value data.
7. The method for removing absolute phase noise with a dead zone of projection as claimed in claim 6, wherein the line detection is Hall transformation line detection.
8. The method for removing absolute phase noise in the existence of the dead zone of projection according to claim 1, wherein the step of eliminating the noise points, correcting the absolute phase straight line to obtain the correct absolute phase value and reconstructing the three-dimensional object comprises the following steps:
acquiring a third difference value through the absolute phase value data of the non-noise point in the effective area and the reference absolute phase value of the reference absolute phase straight line of the same abscissa, acquiring a second average value through the third difference value, and setting the second average value as a reference distance value;
correcting an absolute phase straight line according to the reference distance value and the reference absolute phase straight line;
and acquiring a correct absolute phase value through the corrected absolute phase straight line, and reconstructing the three-dimensional object.
9. An apparatus for removing absolute phase noise in the presence of a dead zone of projection, comprising:
at least one processor and a memory communicatively coupled to the processor; the memory stores instructions executable by the at least one processor to enable the processor to perform the method of any one of claims 1-8 for dead zone elimination of absolute phase noise.
10. A computer-readable storage medium storing computer-executable instructions for causing a computer to perform the method for removing absolute phase noise in the presence of a dead zone of projection as claimed in any one of claims 1 to 8.
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