CN106802137B - A kind of phase developing method and system - Google Patents

Abstract

Embodiments of the present invention provide a phase unwrapping method and system, the method comprising: obtaining a truncated phase of the measured object according to structured light projected on the surface of the measured object; obtaining a reference plane by photographing and obtaining the reference plane unwrapping phase, Perform the unwrapping operation according to the truncated phase and the unwrapped phase of the reference plane to obtain a first phase distribution result; construct a virtual plane continuous phase, and perform the unwrapping operation according to the truncated phase and the virtual plane continuous phase to obtain a second phase distribution Result: The first phase distribution result and the second phase distribution result are fused in the phase region to obtain the unwrapped phase and height distribution results of the measured object. The present invention assists phase unwrapping by adding virtual plane continuous phases, and after performing multiple stages of phase unwrapping, a final correct unwrapping phase is obtained by combining multiple unwrapping phases, the unwrapping speed is fast, and error transmission spread and diffusion are not easy to occur.

Description

A phase unwrapping method and system

technical field

The invention relates to the field of computer measurement and calculation, in particular, to a phase unwrapping method and system.

Background technique

In recent years, with the rapid development of computer technology, optics and optoelectronic technology, the three-dimensional surface measurement of objects is of great significance. Optical three-dimensional surface measurement methods based on phase analysis have been deeply studied and widely used because of their advantages of non-contact, fast measurement speed and high precision. This kind of method modulates the height distribution of the measured surface shape into the phase change of the projected light field, analyzes the obtained deformed fringe pattern, and calculates the corresponding phase distribution to reconstruct the three-dimensional surface shape distribution of the measured object. Since the phase distribution is obtained by the arctangent function, the calculated phase value is truncated within the main value range of the function (-π, π], showing a sawtooth-shaped discontinuous distribution, which is usually called phase truncated. Therefore, Before reconstructing the height distribution of the measured object, the truncated phase must be restored to the original continuous phase, which needs to be corrected by adding or subtracting 2nπ at the phase discontinuity point. This process is phase unwrapping.

The traditional spatial phase unwrapping method is to search and locate the truncation point point by point in the truncated phase two-dimensional space for phase unwrapping. The unwrapping method can avoid such errors, but it needs to project and acquire multiple images with different fringe periods or mark each fringe period in order, and use the relationship between the periods or the coding order to perform phase unwrapping on the time axis. Class methods bring time and complexity to both measurement and reconstruction.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a phase unwrapping method and system to improve the above problems.

An embodiment of the present invention provides a phase unwrapping method, which is applied to a virtual phase plane unwrapping device, and the method includes:

Obtain the truncation phase of the measured object according to the structured light projected on the surface of the measured object;

Obtain the reference plane by shooting and obtain the unwrapped phase of the reference plane, and perform unwrapping operation according to the truncated phase and the unwrapped phase of the reference plane, to obtain a first phase distribution result;

constructing a virtual plane continuous phase, and performing an expansion operation according to the truncated phase and the virtual plane continuous phase to obtain a second phase distribution result;

Phase region fusion is performed on the first phase distribution result and the second phase distribution result to obtain the unwrapped phase and height distribution results of the measured object.

Another embodiment of the present invention provides a phase unwrapping system, applied to a multi-plane phase unwrapping device, the system includes a truncated phase acquisition module, a first unwrapping module, a second unwrapping module, and a fusion module;

The truncated phase acquisition module is used to obtain the truncated phase of the measured object according to the structured light projected on the surface of the measured object;

The first unwrapping module is used to obtain the reference plane by shooting and obtain the unwrapped phase of the reference plane, and perform unwrapping operation according to the truncated phase and the unwrapped phase of the reference plane to obtain a first phase distribution result;

The second expansion module is used to construct a virtual plane continuous phase, and an expansion operation is performed according to the truncated phase and the virtual plane continuous phase to obtain a second phase distribution result;

The fusion module is configured to perform a phase region fusion operation on the first phase distribution result and the second phase distribution result to obtain the unwrapped phase and height distribution results of the measured object.

The phase unwrapping method and system provided by the embodiments of the present invention assist the phase unwrapping of the surface of the object to be measured by constructing a virtual plane continuous phase on the basis of the reference plane unwrapping phase, perform multiple hierarchical phase unwrapping, and combine multiple unwrapped phase results to obtain Get the final correct unwrapped phase. The phase unwrapping method provided by the present invention does not need marking and coding, and the unwrapping speed is fast, and it does not need to perform point-by-point spatial phase unwrapping in a two-dimensional plane, and does not generate error transmission spread and diffusion.

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

FIG. 1 is a schematic block diagram of a virtual phase plane unwrapping apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart of a phase unwrapping method provided by an embodiment of the present invention.

FIG. 3 is a flowchart of sub-steps of step S103 in FIG. 2 .

FIG. 4 is a schematic diagram of a phase unwrapping provided by an embodiment of the present invention.

FIG. 5 is a flowchart of sub-steps of step S105 in FIG. 2 .

FIG. 6 is a flowchart of sub-steps of step S107 in FIG. 2 .

FIG. 7 is a distribution diagram of phase unwrapping results provided by an embodiment of the present invention.

FIG. 8 is a schematic diagram of the phase unwrapping process on the marked line in FIG. 7 .

FIG. 9 is a diagram of a reconstruction height distribution result provided by an embodiment of the present invention.

FIG. 10 is a schematic structural block diagram of a phase unwrapping system provided by an embodiment of the present invention.

FIG. 11 is a schematic structural block diagram of a first expansion module provided by an embodiment of the present invention.

FIG. 12 is a schematic structural block diagram of a second expansion module provided by an embodiment of the present invention.

FIG. 13 is a schematic structural block diagram of a fusion module provided by an embodiment of the present invention.

FIG. 14 is a phase unwrapping result of the first case provided by the embodiment of the present invention.

FIG. 15 is a phase unwrapping result of the second case provided by the embodiment of the present invention.

Icons: 100-virtual phase plane unwrapping device; 110-phase unwrapping system; 111-truncated phase acquisition module; 112-first unwrapping module; 1121-first phase order acquisition sub-module; 1122-first unwrapped phase acquisition sub-module 1123-the first phase distribution acquisition submodule; 113-the second expansion module; 1131-the second phase order acquisition submodule; 1132-the second expansion phase acquisition submodule; 1133-the second phase distribution acquisition submodule; 114 - Fusion module; 1141 - Phase area fusion sub-module; 1142 - Subtraction sub-module; 1143 - Reconstruction sub-module; 120 - Processor; 130 - Memory.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present invention.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

Please refer to FIG. 1 , which is a schematic block diagram of a virtual phase plane unwrapping apparatus 100 according to an embodiment of the present invention. In this embodiment, the virtual phase plane unwrapping apparatus 100 includes a phase unwrapping system 110 , a processor 120 and a memory 130 . Wherein, the memory 130 and the processor 120 are directly or indirectly electrically connected to realize data transmission or interaction. The phase unwrapping system 110 includes at least one software function module that can be stored in the memory 130 in the form of software or firmware or fixed in the operating system of the virtual phase plane unwrapping apparatus 100 . The processor 120 is configured to execute executable modules stored in the memory 130, such as software function modules or computer programs included in the phase unwrapping system 110, so as to perform unwrapping operations on multi-plane truncated phases.

In this embodiment, the virtual phase plane unwrapping apparatus 100 may be, but not limited to, a network server, a database server, or a data processing apparatus installed in the server, and the like.

As shown in FIG. 2 , it is a schematic flowchart of a phase unwrapping method applied to the multi-plane phase unwrapping apparatus 100 shown in FIG. 1 according to an embodiment of the present invention. It should be noted that the method provided in this embodiment is not limited to the sequence described in FIG. 2 and the following. The specific flow shown in FIG. 2 will be described in detail below.

Step S101 , obtaining the cut-off phase of the measured object according to the structured light projected onto the surface of the measured object.

In this embodiment, when the structured light is projected onto the surface of the measured object through the cosine grating, the deformed fringe pattern of the measured object can be obtained. Optionally, a projector or other equipment is generally used for structured light projection. Depending on the coded grating image, a slide projector, a digital projector, a laser that emits a ray beam, or a laser that emits a spot, etc. can be used. Then, an electrical coupling device, a CMOS camera, or other photoelectric sensor arrays can be used to collect images, and the collected images can be transmitted to the virtual phase plane unwrapping apparatus 100, where image processing is performed. Among them, the fringe pattern can be represented by the following formula:

where a(x, y) is the background light intensity, b(x, y) is the fringe contrast, f ₀ is the frequency of the projected grating, is the phase modulation caused by the height distribution.

In order to obtain the relative height distribution of the measured object and eliminate the error of the phase unwrapping system 110, a reference plane can be measured, and the reference deformation fringes of the measured object height distribution h(x, y) can be expressed as:

Transform and analyze the fringe image in the space domain and the time domain to obtain the truncated phase of the measured object.

Optionally, two-dimensional Fourier transform can be performed on the fringe patterns obtained by formula (1) and formula (2), and a suitable filter window is used to filter out the fundamental frequency, and then after two-dimensional inverse Fourier transform can be performed. The complex distribution expressed in exponential form is obtained as follows:

where w(x,y) is the Fourier spectral distribution of b(x,y). Similarly, do the same transformation for the reference stripes, and get the following representation:

Optionally, the complex distributions of equations (3) and (4) can be calculated to obtain their phase differences:

Among them, arctan{} represents the arc tangent function, imag[] represents the complex imaginary part, and real[] represents the complex real part.

It should be noted that, in this embodiment, the method of Fourier transform profilometry is used to obtain the truncated phase. Optionally, the truncated phase can also be obtained by other methods, for example, cosine transform, wavelet transform and S transform in the space domain, fringe phase shift in the time domain, etc., as long as the truncated phase can be obtained, in this embodiment. There are no specific restrictions.

In step S103, a reference plane is obtained by photographing and a reference plane unwrapped phase is acquired, and an unwrapping operation is performed according to the truncated phase and the reference plane unwrapped phase to obtain a first phase distribution result.

Optionally, in this embodiment, the reference plane may be obtained by taking pictures with a camera or obtained by calibration, and the specific implementation manner is not limited in this embodiment.

Specifically, referring to FIG. 3 , step S103 may include three sub-steps of step S1031 , step S1033 and step S1035 .

Step S1031, perform a difference process between the truncated phase and the reference plane unwrapped phase, and compare the difference with 2π to obtain a first phase order.

Optionally, after analyzing the stripes of the measured object to obtain corresponding phase information, the phase of the measured object is usually truncated and distributed within (-π, π]. Without loss of generality, the constructed reference plane has The truncated phase is relatively easy to expand, and the reference plane unwrapped phase φ _o is obtained after a simple spatial row-column expansion. The first phase order K can be obtained by comparing the difference between the two unwrapped phases φ _o with the reference plane and 2π, where K is a positive integer. The first phase order K can guide the unfolding of the truncated phase, and the specific expression can be as follows:

Among them, the corresponding first phase order K can be expressed as:

Among them, the floor function is a round-down function.

Step S1033, obtaining a first unwrapped phase of the measured object according to the first phase order and the unwrapped phase of the reference plane.

After obtaining the correct first phase order K, the unwrapped phase φ ₁ of the measured surface of the measured object can be obtained, which can be used for subsequent phase fusion:

Step S1035 , performing difference processing between the first unwrapped phase and the reference plane unwrapped phase to obtain the first phase distribution result.

Optionally, the process and principle of the phase unwrapping is described by taking a line in the truncated phase distribution of the measured object (peaks function of 256*256 pixels, fringe period p=21 pixels) as an example. As shown in Figure 4, Figure 4(a) is the unwrapped phase distribution of the row on the reference plane, Figure 4(b) is the truncated phase of the row on the measured object, and Figure 4(c) is Figure 4(a) and Figure 4(c). 4(b) The first phase order value K obtained by comparing the difference between the two phase distributions with 2π. Fig. 4(d) is the unwrapped phase corresponding to Fig. 4(b), and Fig. 4(e) is the phase distribution of the unwrapped phase of the measured object and the phase of the reference plane deducted, that is, the phase change caused by the height of the measured object, which can be used to reconstruct the measured object. The measured object corresponds to the height distribution. Among them, the horizontal axis represents the change of the pixel (Pixel) at the X position, and the vertical axis represents the change of the phase (Phase), and the unit is radian (Rad).

Step S105 , constructing a virtual plane continuous phase, and performing an expansion operation according to the truncated phase and the virtual plane continuous phase to obtain a second phase distribution result.

Optionally, in this embodiment, when the surface shape of the measured object is relatively complex or the number of phase truncations is large, a new virtual plane needs to be virtualized on the basis of the reference plane to assist the phase unwrapping of the measured surface.

Optionally, a virtual plane phase needs to be constructed. It should be noted that, in this embodiment, the constructed virtual plane may be one or multiple. Optionally, the following relationship is satisfied between the continuous phase φ _s of the virtual plane and the unwrapped phase φ _o of the reference plane:

(φ _o -2nπ)<φ _s <(φ _o +2nπ)

where n is a positive integer (1,2,3,...,n). That is, the virtual plane continuous phase φ _s should be slightly smaller than φ _o +2nπ or slightly larger than φ _o −2nπ, so that the phase truncation order can be accurately determined.

Specifically, referring to FIG. 5 , step S105 may include three sub-steps of step S1051 , step S1053 and step S1055 .

Step S1051, performing a difference process between the truncated phase and the continuous phase of the virtual plane, and comparing the difference with 2π to obtain a second phase order.

Step S1053: Obtain a second unwrapped phase of the measured object according to the second phase order and the virtual plane continuous phase.

Step S1055 , performing difference processing between the second unwrapped phase and the unwrapped phase of the reference reference plane to obtain the second phase distribution result.

Optionally, the general steps of obtaining the second phase distribution result are similar to the steps of obtaining the first phase distribution result, and details are not described here.

That is, after obtaining the continuous phase of the virtual plane, the unwrapping operation is performed according to the above formulas (6) to (8) to obtain the unwrapped phase of the measured object, and the subsequent phase fusion can be performed by combining the unwrapped phase and the unwrapped phase obtained based on the reference plane.

Step S107: Perform phase region fusion on the first phase distribution result and the second phase distribution result to obtain the unwrapped phase and height distribution results of the measured object.

Specifically, referring to FIG. 6 , step S107 may include three sub-steps of step S1071 , step S1073 and step S1075 .

Step S1071, perform phase region fusion on the first phase distribution result and the second phase distribution result.

Step S1073, deducting the phase order introduced when constructing the continuous phase of the virtual plane to obtain the phase distribution of the measured object.

Without loss of generality, when the virtual plane is used for truncated phase unwrapping, the phase order changes will be artificially caused, so it is necessary to eliminate the artificially introduced phase order changes when multiple unwrapped phase regions are fused.

Step S1075, reconstruct the height distribution of the measured object according to the relationship between the unfolded phase and the height of the measured object.

In the specific implementation, select the measured object (6.3*peaks function of 256*256 pixels, fringe period p=21 pixels), after obtaining the reference plane unwrapping phase φ _o by the row-column phase unwrapping method, the obtained reference plane unwrapping the phase φ _o Perform the first unwrapping operation according to formulas (6) to (8) and deduct the unwrapped phase of the reference plane to obtain the first phase distribution result, as shown in Figure 7(a), where the image on the X-axis (Position X) The unit is pixel (Pixel), and the image unit on the Y axis (Position Y) is pixel (Pixel).

According to the construction requirements of the virtual plane, the continuous phases φ _s1 and φ _s2 of the virtual plane are obtained, where φ _s1 =φ _o -2π+1, and φ _s2 =φ _o +2π-1. Perform the second and third unwrapping operations on the obtained virtual plane continuous phases φ _s1 and φ _s2 according to formulas (6) to (8) and deduct the reference plane unwrapping phase to obtain the second phase distribution result and the third phase distribution result. , as shown in Fig. 7(b) and Fig. 7(c), respectively.

Selecting the column of dotted lines in Fig. 7(a), Fig. 7(b) and Fig. 7(c), the corresponding phase distribution obtained is shown in Fig. 8(a), where Fig. 8(a) represents Fig. 7( a) The dashed curve expands the wrong part, which can be merged with the curve representing the dashed line in Fig. 7(b), then in Fig. 7(a) area 1 and area 2 are shown in Fig. 7(b). The second unwrapping operation is continuous, so the phase distributions of the two unwrappings can be fused to obtain the correct phase for region 1 and region 2.

If the solid line column in Figure 7(a), Figure 7(b) and Figure 7(c) is selected, the corresponding phase distribution obtained is shown in Figure 8(b). In Fig. 8(b), the truncated part of the curve showing the solid line in Fig. 7(a) has been fused into the correct phase in region 2 by Fig. 7(b) (Fig. 8(a)), and the undeveloped part behind the curve can be The fusion is performed using the curve in Fig. 8(b) representing the solid line portion of Fig. 7(c). In Fig. 7(a), the region 3 is continuous after the second unwrapping operation shown in Fig. 7(c), so the correct phase of the region 3 can be obtained by using the phase distribution of the two unwrapping. Finally, the correct unwrapped phase of the measured object is obtained, as shown in Figure 7(d). Furthermore, the reconstructed height distribution of the measured object is obtained, as shown in Figure 9, where the three-dimensional image of the measured object is represented by pixels at the X position, the Y position, and the height position, and the unit of height is millimeters (mm).

As shown in FIG. 10 , it is a functional module block diagram of a phase unwrapping system 110 provided by an embodiment of the present invention. The phase unwrapping system 110 includes a truncated phase acquisition module 111 , a first unwrapping module 112 , a second unwrapping module 113 and a fusion module 114 . Each functional module shown in FIG. 10 will be described in detail below.

The truncation phase obtaining module 111 is configured to obtain the truncation phase of the object to be measured according to the structured light projected onto the surface of the object to be measured. This module can be used to perform step S101 shown in FIG. 2 .

The first unwrapping module 112 is configured to obtain a reference plane by photographing and obtain the unwrapped phase of the reference plane, and perform unwrapping operations according to the truncation phase and the unwrapped phase of the reference plane, to obtain a first phase distribution result. This module can be used to perform step S103 shown in FIG. 2 .

The second unwrapping module 113 is configured to construct a virtual plane continuous phase, and perform unwrapping operations according to the truncation phase and the virtual plane continuous phase to obtain a second phase distribution result. This module can be used to perform step S105 shown in FIG. 2 .

The fusion module 114 is configured to perform phase region fusion of the first phase distribution result and the second phase distribution result to obtain the unwrapped phase and height distribution results of the measured object. This module can be used to perform step S107 shown in FIG. 2 .

Specifically, referring to FIG. 11 , the first unwrapping module 112 includes a first phase order obtaining sub-module 1121 , a first unwrapping phase obtaining sub-module 1122 and a first phase distribution obtaining sub-module 1123 .

The first phase order obtaining sub-module 1121 is configured to perform difference processing between the truncated phase and the reference plane unwrapped phase, and compare the difference with 2π to obtain the first phase order. This module can be used to perform step S1031 shown in FIG. 3 .

The first unwrapped phase acquisition sub-module 1122 is configured to obtain the first unwrapped phase of the measured object according to the first phase order and the unwrapped phase of the reference plane. This module can be used to perform step S1033 shown in FIG. 3 .

The first phase distribution obtaining sub-module 1123 is configured to perform difference processing between the first unwrapped phase and the unwrapped phase of the reference plane to obtain a first phase distribution result. This module can be used to perform step S1035 shown in FIG. 3 .

Specifically, please refer to FIG. 12 , the second unwrapping module 113 includes a second phase order obtaining sub-module 1131 , a second unwrapping phase obtaining sub-module 1132 and a second phase distribution obtaining sub-module 1133 .

The second phase order obtaining sub-module 1131 is configured to perform difference processing between the truncated phase and the virtual plane continuous phase, and compare the difference with 2π to obtain the second phase order. This module can be used to perform step S1051 shown in FIG. 5 .

The second unwrapped phase acquisition sub-module 1132 is configured to obtain the second unwrapped phase of the measured object according to the second phase order and the virtual plane continuous phase. This module can be used to perform step S1053 shown in FIG. 5 .

The second phase distribution acquisition sub-module 1133 is configured to perform difference processing between the second unwrapped phase and the reference plane unwrapped phase to obtain the second phase distribution result. This module can be used to perform step S1055 shown in FIG. 5 .

Specifically, please refer to FIG. 13 , the fusion module 114 includes a phase region fusion sub-module 1141 , a subtraction sub-module 1142 and a reconstruction sub-module 1143 .

The phase region fusion sub-module 1141 is configured to perform phase region fusion on the first phase distribution result and the second phase distribution result. This module can be used to perform step S1071 shown in FIG. 6 .

The first subtraction sub-module 1142 is used to subtract the phase order introduced when constructing the continuous phase of the virtual plane to obtain the phase distribution of the measured object. This module can be used to perform step S1073 shown in FIG. 6 .

The reconstruction sub-module 1143 is configured to reconstruct the height distribution of the measured object according to the relationship between the unwrapped phase and the height of the measured object. This module can be used to perform step S1075 shown in FIG. 6 .

For the specific operation process of each functional module provided in this embodiment, reference may be made to the description of the corresponding steps in the flow chart of the above method.

In order to illustrate the phase unwrapping method provided by this embodiment more clearly, two specific test cases of the method are exemplarily given below.

first case

In this case, the measured object is a model of a cat face, as shown in Figure 14(a), and the obtained truncated phase of the measured object is shown in Figure 14(b). as follows:

a. The reference plane unwrapped phase φ _o of the reference plane is obtained by the spatial row and column phase unwrapping method.

b. Perform the first phase unwrapping operation on the obtained reference plane unwrapped phase φ _o according to formulas (6) to (8) and deduct the reference plane unwrapped phase to obtain the first phase distribution result, as shown in Figure 14(c). According to the construction requirements of the virtual plane, the continuous phase of the virtual plane is obtained as φ _s1 =φ _o -2π+1. Based on the continuous phase of the virtual plane, the second phase unwrapping operation is performed according to the above formula and the unwrapped phase of the reference plane is deducted to obtain The second phase distribution result is shown in Fig. 14(d).

c. The phase of the unexpanded region in the first unwrapping operation (Fig. 14(c)) is continuous after the second phase unwrapping operation (Fig. 14(d)), as shown in Fig. 14(e), the fusion The phase distribution of the twice unwrapping is used to obtain the final phase unwrapping distribution of the measured object, as shown in Figure 14(f).

Second case

In this case, the measured object is a three-layered tower-shaped object, as shown in Figure 15(a), and the obtained truncated phase of the measured object is shown in Figure 15(b). The decomposition steps of phase unwrapping are as follows:

a. The reference plane unwrapped phase φ _o of the reference plane is obtained by the spatial row and column phase unwrapping method.

b. Perform the first phase unwrapping operation on the obtained reference plane unwrapped phase φ _o according to formulas (6) to (8) and deduct the reference plane unwrapped phase to obtain the first phase distribution result, as shown in Figure 15(c). According to the construction requirements of the virtual plane, the continuous phase of the virtual plane is obtained as φ _s1 =φ _o -2π+1. Based on the continuous phase of the virtual plane, the second phase unwrapping operation is performed according to the above formula and the unwrapped phase of the reference plane is deducted to obtain The second phase distribution result.

c. The phase of the unexpanded region in the above-mentioned first unwrapping operation is continuous after the second phase unwrapping operation, as shown in Figure 15(c), fuse the phase distributions of the two unwrapping to obtain the final phase of the measured object Expand the distribution, as shown in Figure 15(d).

To sum up, the phase unwrapping method and system provided by the present invention assists the phase unwrapping of the measured surface by constructing a virtual plane continuous phase on the basis of the reference plane unwrapping phase, performing multiple hierarchical phase unwrapping, and combining multiple unwrapping phases. result to get the final correct unwrapped phase. The phase unwrapping method provided by the present invention does not need marking and coding, and the unwrapping speed is fast, and it does not need to perform point-by-point spatial phase unwrapping in a two-dimensional plane, and does not generate error transmission spread and diffusion.

In the embodiments provided in this application, it should be understood that the disclosed apparatus and method may also be implemented in other manners. The apparatus embodiments described above are merely illustrative, eg, the flowcharts and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatuses, methods and computer program products according to embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code that contains one or more functions for implementing the specified logical function(s) executable instructions. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It is also noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented in dedicated hardware-based systems that perform the specified functions or actions , or can be implemented in a combination of dedicated hardware and computer instructions.

In addition, each functional module in each embodiment of the present invention may be integrated to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present invention can be embodied in the form of a software product in essence, or the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: a U disk, a removable hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk and other media that can store program codes.

It should be noted that, herein, the terms "comprising", "comprising" or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements, It also includes other elements not expressly listed or inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention. It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

Claims (8)

1. A phase unwrapping method applied to a virtual phase plane unwrapping device, the method comprising:

obtaining a truncation phase of the measured object according to the structured light projected to the surface of the measured object;

obtaining a reference plane through shooting, obtaining a reference plane unfolding phase, and carrying out unfolding operation according to the truncation phase and the reference plane unfolding phase to obtain a first phase distribution result;

constructing a virtual plane continuous phase, and performing unfolding operation according to the truncation phase and the virtual plane continuous phase to obtain a second phase distribution result;

performing phase region fusion on the first phase distribution result and the second phase distribution result to obtain an expansion phase and height distribution result of the measured object;

the step of performing an unwrapping operation according to the truncated phase and the reference plane unwrapped phase to obtain a first phase distribution result includes:

and performing difference processing on the truncated phase and the reference plane unwrapped phase, comparing the difference with 2 pi, and obtaining a first phase level according to the following formula:

wherein,is the truncated phase of the object to be measured, phi_oExpanding the phase for the reference plane, wherein K is the first phase order, and the floor function is a down-rounding function;

and calculating to obtain a first unwrapped phase of the measured object according to the first phase order and the reference plane unwrapped phase and according to the following formula:

wherein phi is₁A first unwrapped phase for the object under test;

and performing difference processing on the first unwrapped phase and the reference plane unwrapped phase to obtain a first phase distribution result.

2. The phase unwrapping method according to claim 1, wherein the virtual-plane continuous phase and the reference-plane unwrapped phase satisfy the following relationship:

(φ_o-2nπ)<φ_s<(φ_o+2nπ)

wherein phi is_sFor the virtual plane continuous phase, phi_oThe phases are unwrapped for the reference plane, n being a positive integer (1,2,3, …, n).

3. The phase unwrapping method according to claim 2, wherein the step of performing an unwrapping operation based on the truncated phase and the virtual-plane continuous phase to obtain a second phase-distribution result includes:

carrying out difference processing on the truncation phase and the virtual plane continuous phase, and comparing the difference with 2 pi to obtain a second phase level;

obtaining a second expansion phase of the measured object according to the second phase level and the virtual plane continuous phase;

and carrying out difference processing on the second unwrapped phase and the reference plane unwrapped phase to obtain a second phase distribution result.

4. The phase unwrapping method according to claim 1, wherein the step of performing phase region fusion on the first phase distribution result and the second phase distribution result to obtain an unwrapped phase and height distribution result of the object to be measured includes:

performing phase region fusion on the first phase distribution result and the second phase distribution result;

deducting the phase order introduced when the virtual plane continuous phase is constructed to obtain the phase distribution of the measured object;

and reconstructing the height distribution of the measured object according to the relationship between the expansion phase and the height of the measured object.

5. A phase unfolding system is applied to a virtual phase plane unfolding device and is characterized by comprising a truncated phase acquisition module, a first unfolding module, a second unfolding module and a fusion module;

the truncation phase acquisition module is used for acquiring the truncation phase of the measured object according to the structured light projected to the surface of the measured object;

the first unfolding module is used for obtaining a reference plane through shooting, obtaining a reference plane unfolding phase, and carrying out unfolding operation according to the truncation phase and the reference plane unfolding phase to obtain a first phase distribution result;

the second unfolding module is used for constructing a virtual plane continuous phase, and carrying out unfolding operation according to the truncation phase and the virtual plane continuous phase to obtain a second phase distribution result;

the fusion module is used for carrying out phase region fusion operation on the first phase distribution result and the second phase distribution result to obtain an expansion phase and height distribution result of the object to be measured;

the first unfolding module comprises a first phase level acquisition submodule, a first unfolding phase acquisition submodule and a first phase distribution acquisition submodule;

the first phase level acquisition submodule is used for carrying out difference processing on the truncated phase and the reference plane unwrapped phase, comparing the difference with 2 pi, and obtaining a first phase level according to the following formula:

wherein,is the truncated phase of the object to be measured, phi_oUnwrapping phase for reference plane, K beingIn the first phase order, the floor function is a down-rounding function;

the first unwrapped phase acquisition submodule is used for calculating a first unwrapped phase of the measured object according to the first phase order and the reference plane unwrapped phase and according to the following formula:

wherein phi is₁A first unwrapped phase for the object under test;

the first phase distribution obtaining submodule is used for carrying out difference processing on the first unwrapped phase and the reference plane unwrapped phase to obtain a first phase distribution result.

6. The phase unwrapping system according to claim 5, wherein the virtual-plane continuous phase and the reference-plane unwrapped phase satisfy the following relationship:

(φ_o-2nπ)<φ_s<(φ_o+2nπ)

wherein phi is_sFor the virtual plane continuous phase, phi_oThe phases are unwrapped for the reference plane, n being a positive integer (1,2,3, …, n).

7. The phase unwrapping system of claim 5, wherein the second unwrapping module includes a second phase level acquisition sub-module, a second unwrapped phase acquisition sub-module, and a second phase distribution acquisition sub-module;

the second phase level obtaining submodule is used for carrying out difference processing on the truncated phase and the virtual plane continuous phase and comparing the difference with 2 pi to obtain a second phase level;

the second unwrapped phase acquisition submodule is used for acquiring a second unwrapped phase of the measured object according to the second phase level and the virtual plane continuous phase;

and the second phase distribution acquisition submodule is used for carrying out difference processing on the second unwrapped phase and the reference plane unwrapped phase to obtain a second phase distribution result.

8. The phase unwrapping system according to claim 5, wherein the fusion module includes a phase region fusion sub-module, a subtraction sub-module, and a reconstruction sub-module;

the phase region fusion submodule is used for performing phase region fusion on the first phase distribution result and the second phase distribution result;

the deduction submodule is used for deducting the phase order introduced when the virtual plane continuous phase is constructed to obtain the phase distribution of the measured object;

and the reconstruction submodule is used for reconstructing the height distribution of the measured object according to the relationship between the expansion phase and the height of the measured object.