WO2021168971A1 - Double-fringe projection phase unwrapping method and apparatus based on color segmentation - Google Patents

Abstract

Disclosed in the present invention are a double-fringe projection phase unwrapping method and apparatus based on color segmentation. The method comprises: designing a projection fringe pattern and a color fringe pattern; projecting the color fringe pattern to obtain a deformed color pattern, and projecting the projection fringe pattern to obtain a deformed fringe pattern; performing color region division on the deformed color pattern to obtain corresponding deformed monochromatic regions, and segmenting the deformed fringe pattern into segmented fringe patterns according to the positions of the deformed monochromatic regions; and for each segmented fringe pattern, separately obtaining a wrapped phase map and establishing a lookup table of a corresponding region, and according to a calculation formula of an absolute phase, recovering the absolute phase of the segmented fringe pattern by means of the wrapped phase map and the lookup table, thereby recovering a three-dimensional topography of an object to be measured. According to the present invention, the measurement range and precision based on a fringe projection phase unwrapping algorithm are widened and improved, and thus, phase unwrapping can be accurately performed on the projection fringe pattern of any wavelength under any given projector resolution, and the projector resolution is fully utilized.

Description

Double fringe projection phase expansion method and device based on color segmentation Technical field

The invention relates to the technical field of three-dimensional shape measurement, in particular to a double fringe projection phase expansion method and device based on color segmentation.

Background technique

Three-dimensional measurement methods are mainly divided into two types: contact type and non-contact type. Non-contact type has become a research hotspot due to its simplicity, simplicity, and high accuracy. And the three-dimensional measurement method based on fringe projection is widely used in various fields. The three-dimensional measurement method based on fringe projection uses a projector to project one or several sets of fringe patterns onto the object to be measured, and then photograph the object to be measured with a camera The deformed fringe pattern on the above is analyzed through a series of algorithms, and the three-dimensional three-dimensional of the object to be measured is finally restored.

The existing fringe projection phase unwrapping method is mainly based on the principle of multi-frequency heterodyne, and its phase unwrapping process mainly relies on the main phase values of grating images at different frequencies. In the method based on the principle of external frequency heterodyne, because the selected fringe needs to be a combination of low-frequency and high-frequency fringes, and the expansion of low-frequency fringes must have only one fringe period in the entire image, low-frequency fringes are greatly affected by noise. The multi-fringe projection algorithm based on frequency selection improves the method based on the external frequency heterodyne principle. This method establishes the special relationship between the wrap phase and the fringe order through analysis and can also correctly restore the absolute phase, and the fringe selection limits It is greatly reduced, but it cannot satisfy that the total pixels of the projected picture must be an integer multiple of the number of pixels contained in each stripe. The multi-fringe projection algorithm based on wavelength selection is improved, and the multi-fringe projection algorithm based on frequency selection is improved, so that the fringe designed can make full use of all pixels of the projected image.

The double fringe projection phase expansion method based on wavelength selection requires that the parameters of wavelength selection must satisfy the resolution of the projector in a specific range, that is, the resolution of the projector must be less than the product of the selected wavelength, R≤λ ₁ λ ₂ . If it exceeds the limited resolution range, errors will occur during phase unwrapping, so the resolution of the projector is not fully utilized.

Summary of the invention

The purpose of the present invention is to solve at least one of the technical problems existing in the prior art, provide a double fringe projection phase unwrapping method and device based on color segmentation, and improve the measurement range and accuracy of the fringe projection phase unwrapping algorithm.

The solution to the technical problem of the present invention is:

In the first aspect, the present invention provides a double fringe projection phase unwrapping method based on color segmentation, including:

Choose two fringe wavelengths to design the projection fringe pattern, which is composed of the color fringe pattern corresponding to the projector resolution and the projection fringe pattern design, and the color fringe pattern is composed of at least two color bars with different colors arranged alternately;

Project the color fringe pattern onto the object to be measured to obtain a deformed color image, and project the projected fringe pattern onto the object to be measured to obtain a deformed fringe pattern;

Perform at least two color area divisions on the deformed color image to obtain a corresponding deformed monochrome area, and divide the deformed fringe image into at least two segmented fringe images according to the position of the deformed monochrome area;

For each segmented fringe image, obtain the wrapped phase image and establish a look-up table for the corresponding area, and restore the absolute phase of the segmented fringe image from the wrapped phase image and the look-up table according to the absolute phase calculation formula;

The three-dimensional shape of the object to be measured is recovered from the absolute phase of all the segmented fringe patterns.

Further, the color fringe pattern corresponding to the resolution of the projector and the projection fringe pattern design, the color fringe pattern consisting of at least two color bars with different colors arranged alternately includes:

The size of the color fringe pattern is the same as that of the projected fringe pattern;

The color stripe diagram is designed by the design formula, the design formula is as follows:

r ₂ =λ ₁ λ ₂ ,

r ₁ =R-(n-1)r ₂ ,

The number of color bars is n, R is the resolution of the projector, the color area of the color bar at the bottom is r ₁ , and the color area of the remaining color bars is r ₂ ,

Indicates rounding up, λ ₁ and λ ₂ are the wavelengths of the projected fringes.

Further, the step of dividing the deformed color image by color area at least twice to obtain the corresponding deformed monochrome area, and dividing the deformed fringe image into at least two segmented fringe images according to the position of the deformed monochrome area includes:

The number of divisions of the color area is the same as the number of color bars, the number of deformed monochrome areas is the same as the number of divisions of color areas, and the number of divided fringe patterns is the same as the number of deformed monochrome areas.

Further, the performing color area division on the deformed color image at least twice to obtain the corresponding deformed monochrome area includes:

Steps to divide the color area:

Set the color segmentation threshold δ, take any point a in the deformed color map, and find the approximate color D(z,a) of each point z and point a in the deformed color map. If D(z,a)≤δ, then point z Similar to the color of point a;

All the points z whose colors are similar to the point a are composed to obtain an unprocessed divided area;

Perform denoising processing on unprocessed divided areas to obtain deformed monochrome areas;

Delete the deformed monochrome area in the deformed color map and replace the original deformed color map.

Further, calculating the color approximate value D(z, a) of each point z and point a of the deformed color map includes:

The calculation formula for the approximate color value D(z,a) of point z and point a is:

The subscripts R, G, and B represent the RGB components of point z and point a, respectively.

Further, the performing denoising processing on the unprocessed divided area includes:

Fill holes in untreated divided areas;

Filter out the areas with smaller connected domains in the unprocessed divided areas.

Further, for each segmentation fringe pattern, separately acquiring the wrapped phase image and establishing a look-up table of the corresponding region, according to the absolute phase calculation formula, recovering the absolute phase of the segmentation fringe image from the wrapped phase image and the look-up table includes:

For each segmented fringe image, through fringe analysis technology, obtain the corresponding phase image that is distributed between -π and π

Then the lookup table of the corresponding area is established by solving the inequality. The header of the established lookup table includes: m ₁ , m ₂ , m ₂ λ ₂ -m ₁ λ ₁ , where m ₁ , m _{2 are required} to restore the three absolute phases. Required fringe order,

The inequality is as follows:

0≤m ₁ ＜R/λ ₁ , 0≤m ₂ ＜R/λ ₂ ,

Where λ ₁ , λ ₂ are the fringe wavelengths, m ₁ , m _{2 are the} order of the fringes,

Is the wrapped phase map, and R is the resolution of the projector;

Establish a one-to-one correspondence between the package phase image and the fringe order required for phase unwrapping according to the obtained package phase image and look-up table, and calculate

The value of [m ₂ λ ₂ -m ₁ λ ₁ ] is rounded to the nearest whole number, and the closest row is found in the corresponding lookup table, and the m ₁ and m ₂ values of the same line are recorded;

According to the calculation formula of absolute phase,

Value and the obtained m ₁ , m ₂ values are substituted into the above formula for phase expansion, and the absolute phase of the segmented fringe pattern is restored,

Absolute phase calculation formula:

Among them, φ ₁ and φ ₂ are the absolute phases to be restored.

In the second aspect, the present invention provides a dual fringe projection phase unwrapping device based on color segmentation, including:

The initialization module is used to select two fringe wavelengths to design the projection fringe pattern, which is composed of the color fringe pattern corresponding to the projector resolution and the projection fringe pattern design, and the color fringe pattern is composed of at least two color bars with different colors alternately arranged;

The projection module is used to project the color fringe pattern onto the object to be measured to obtain a deformed color image, and project the projected fringe pattern onto the object to be measured to obtain the deformed fringe pattern;

The segmentation module is used to divide the deformed color image into at least two color areas and obtain the corresponding deformed monochrome area, and divide the deformed fringe image into at least two segmented fringe images according to the position of the deformed monochrome area;

The table building operation module is used to obtain the wrapped phase image for each segmentation fringe image and establish a lookup table for the corresponding area. According to the absolute phase calculation formula, the absolute phase of the segmentation fringe image is restored from the wrapped phase image and the lookup table;

The shape restoration module is used to restore the three-dimensional shape of the object to be measured from the absolute phase of all the segmented fringe patterns.

In the third aspect, the present invention provides a dual fringe projection phase unwrapping device based on color segmentation,

It includes at least one control processor and a memory for communicating with the at least one control processor; the memory stores instructions executable by the at least one control processor, and the instructions are executed by the at least one control processor to enable the at least one control processor The double fringe projection phase expansion based on color segmentation as described above can be performed.

In a fourth aspect, the present invention provides a computer-readable storage medium, the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to make the computer execute the above-mentioned color segmentation-based double fringe projection phase unwrapping .

In a fifth aspect, the present invention also provides a computer program product, the computer program product includes a computer program stored on a computer-readable storage medium, the computer program includes program instructions, when the program instructions are executed by a computer , Let the computer perform the phase expansion of the double fringe projection based on color segmentation as described above.

One or more technical solutions provided in the embodiments of the present invention have at least the following beneficial effects: The present invention provides a double fringe projection phase unwrapping method and device based on color segmentation, and the purpose is to improve the measurement range of the fringe projection phase unwrapping algorithm. And accuracy, so that it can project fringe patterns of any wavelength under any given projector resolution to accurately perform phase expansion, make full use of the projector's resolution, and improve the measurement of the fringe projection phase expansion algorithm. Range and accuracy.

Description of the drawings

The invention will be further described below in conjunction with the drawings and embodiments;

FIG. 1 is a flowchart of a double fringe projection phase unwrapping method based on color segmentation according to a first embodiment of the present invention;

2 is a specific method flowchart of step S100 in the double fringe projection phase unwrapping method based on color segmentation according to the first embodiment of the present invention;

3 is a specific method flowchart of step S300 in the double fringe projection phase unwrapping method based on color segmentation according to the first embodiment of the present invention;

4 is a specific method flowchart of step S330 in the double fringe projection phase expansion method based on color segmentation according to the first embodiment of the present invention;

5 is a specific method flowchart of step S400 in the double fringe projection phase expansion method based on color segmentation according to the first embodiment of the present invention;

6 is a schematic structural diagram of a dual fringe projection phase unwrapping device based on color segmentation according to a second embodiment of the present invention;

7 is a schematic structural diagram of a double fringe projection phase unwrapping device based on color segmentation according to a third embodiment of the present invention;

100-Double fringe projection phase unwrapping device based on color segmentation, 110-initialization module, 120-projection module, 130-segmentation module, 140-table building operation module, 150-restoration module, 200-double fringe based on color segmentation Projection phase unwrapping equipment, 210-control processor, 220-memory.

Detailed ways

In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not used to limit the present invention.

It should be noted that if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, and all fall within the protection scope of the present invention. In addition, although the functional modules are divided in the schematic diagram of the device, and the logical sequence is shown in the flowchart, in some cases, the module division in the device may be different from the module division in the device, or the sequence shown in the flowchart may be executed. Or the steps described.

In the first embodiment of the present invention, as shown in FIG. 1, the double fringe projection phase expansion method based on color segmentation includes:

S100. Select two fringe wavelengths to design the projection fringe pattern, which is composed of the projector resolution and the color fringe pattern corresponding to the projection fringe pattern design, and the color fringe pattern is composed of at least two color bars with different colors arranged alternately;

S200. Project the color fringe pattern onto the object to be measured to obtain a deformed color image, and project the projected fringe pattern onto the object to be measured to obtain the deformed fringe pattern;

S300. Performing at least two color area divisions on the deformed color image to obtain a corresponding deformed monochrome area, and dividing the deformed fringe image into at least two segmented fringe images according to the position of the deformed monochrome area;

S400: For each segmentation fringe pattern, obtain the wrapped phase image separately and establish a lookup table for the corresponding area, and restore the absolute phase of the segmentation fringe image from the wrapped phase image and the lookup table according to the absolute phase calculation formula;

S500: Restore the three-dimensional shape of the object to be measured from the absolute phases of all the segmented fringe patterns.

In the above embodiment, taking the projector resolution R=256 as an example, the specific steps are as follows:

Choose the fringe wavelength λ ₁ =8, λ ₂ =15 to design the projection fringe pattern. According to the resolution of the projector and the projection fringe pattern, design a color fringe pattern composed of red, green and blue stripes arranged alternately; change the color fringe pattern The deformed color map is projected, and the projected fringe map is projected to obtain the deformed fringe map; the deformed color map is divided into three color regions to obtain three deformed monochrome regions, and then the deformed fringe map is divided into corresponding ones according to the position of the deformed monochrome region The three segmentation fringe patterns; for each segmentation fringe pattern, obtain its corresponding wrapped phase image, and establish its corresponding look-up table, use the corresponding wrapped phase image and look-up table, according to the absolute phase calculation formula, restore each The absolute phase of the segmented fringe pattern; the absolute phase of each segmented fringe pattern restores the three-dimensional shape of the object to be measured, and the absolute phase of all the segmented fringe patterns restores the three-dimensional shape of the object to be measured. The invention improves the measurement range and accuracy based on the fringe projection phase unwrapping algorithm, so that it can project fringe patterns of any wavelength under any given projector resolution and can perform phase unwrapping accurately and without error, and make full use of the projector's Resolution improves the measurement range and accuracy of the fringe projection phase unwrapping algorithm.

As shown in Figure 2, step S100 includes:

S110. The size of the color fringe pattern is the same as that of the projected fringe pattern;

S120. Design the color stripe pattern by the design formula, the design formula is as follows:

r ₂ =λ ₁ λ ₂ ,

r ₁ =R-(n-1)r ₂ ,

The number of color bars is n, R is the resolution of the projector, the color area of the color bar at the bottom is r ₁ , and the color area of the remaining color bars is r ₂ ,

Indicates rounding up, λ ₁ and λ ₂ are the wavelengths of the projected fringes.

In the above embodiment, taking the projector resolution R=256, the fringe wavelength of the projection fringe pattern λ ₁ = 8, λ ₂ = 15 as an example, the specific steps are as follows:

The size of the color fringe pattern is the same as the projected fringe pattern; the color fringe pattern is designed by the projector resolution and the projection fringe pattern. The color area of the remaining color bars is r ₂ ＝λ ₁ λ ₂ ＝8*15=120, color fringe The number of color bars in the figure

The color range of the color bar at the bottom is r ₁ =R-(n-1)r ₂ =256-(3-1)*120=16.

Step S300 includes:

The number of divisions of the color area is the same as the number of color bars, the number of deformed monochrome areas is the same as the number of divisions of color areas, and the number of divided fringe patterns is the same as the number of deformed monochrome areas.

In the above embodiment, the number of color bars determines the number of divisions of the color area. Each time the color area is divided, a deformed monochrome area is obtained, and the number of divided fringe patterns is the same as the number of deformed monochrome areas.

As shown in FIG. 3, performing at least two color area divisions on the deformed color image and obtaining the corresponding deformed monochrome area in step S300 includes:

Steps to divide the color area:

S310. Set the color segmentation threshold δ, take any point a in the deformed color map, and find the color approximate value D(z, a) of each point z and point a of the deformed color map. If D(z, a) ≤ δ, then The color of point z is similar to that of point a;

S320. All points z whose colors are similar to point a are formed to obtain an unprocessed divided area;

S330: Perform denoising processing on the unprocessed divided area to obtain a deformed monochromatic area;

S340. Delete the deformed monochrome area in the deformed color map and replace the original deformed color map.

In the above embodiment, according to the steps of dividing the color area, each time the color area is divided, a deformed monochrome area is obtained from the deformed color map; then the deformed monochrome area in the deformed color map is deleted to become a new deformed color map .

As shown in FIG. 3, calculating the approximate color value D(z,a) of each point z and point a of the deformed color image in step S310 includes:

The calculation formula for the approximate color value D(z,a) of point z and point a is:

The subscripts R, G, and B represent the RGB components of point z and point a, respectively.

In the above-mentioned embodiment, the calculation formula for the approximate value of the color of the point z and the point a is given, and related operations can be performed.

As shown in FIG. 4, performing denoising processing on the unprocessed divided area in step S330 includes:

S331. Filling holes in the untreated divided area;

S332: Filter out areas with smaller connected domains in the unprocessed divided areas.

In the foregoing embodiment, the holes existing in the unprocessed divided areas are filled, and then the areas with smaller connected domains in the unprocessed divided areas are filtered out, and the areas with smaller connected domains are uniformly divided into the same deformed monochrome area.

As shown in Fig. 5, step S400 includes:

S410. For each segmented fringe image, obtain the corresponding phase image that is distributed between -π and π through fringe analysis technology

Then the lookup table of the corresponding area is established by solving the inequality. The header of the established lookup table includes: m ₁ , m ₂ , m ₂ λ ₂ -m ₁ λ ₁ , where m ₁ , m _{2 are required} to restore the three absolute phases. Required fringe order,

The inequality is as follows:

0≤m ₁ ＜R/λ ₁ , 0≤m ₂ ＜R/λ ₂ ,

Where λ ₁ , λ ₂ are the fringe wavelengths, m ₁ , m _{2 are the} order of the fringes,

Is the wrapped phase map, and R is the resolution of the projector;

S420. Establish a one-to-one correspondence between the wrapped phase image and the fringe order required for phase unwrapping according to the obtained wrapped phase image and the look-up table, and calculate

The value of [m ₂ λ ₂ -m ₁ λ ₁ ] is rounded to the nearest whole number, and the closest row is found in the corresponding lookup table, and the m ₁ and m ₂ values of the same line are recorded;

S430. According to the calculation formula of absolute phase,

Value and the obtained m ₁ , m ₂ values are substituted into the above formula for phase expansion, and the absolute phase of the segmented fringe pattern is restored,

Absolute phase calculation formula:

Among them, φ ₁ and φ ₂ are the absolute phases to be restored.

In the above embodiment, taking the projector resolution R=256, the fringe wavelength of the projected fringe pattern λ ₁ = 8, λ ₂ = 15 as an example, the specific steps are as follows: The design consists of three color bars of red, green, and blue alternately arranged The color fringe pattern is composed of: the color fringe pattern is projected into a deformed color map, and the projected fringe pattern is projected to obtain a deformed fringe map; the deformed color map is divided into three color areas to obtain three deformed monochrome areas, and then according to the deformed monochrome area The position of the deformed fringe image is divided into three corresponding segmentation fringe images;

Obtain the wrapped phase image from -π to π from the first segmented fringe image

And the first area of the lookup table established by inequality is as follows:

m 1 (y)

m 2 (y)

m 2 (y)λ 2 -m 1 (y)λ 1

0	0	0
1	0	-8
1	1	7
2	1	-1
3	1	-9
3	2	6
4	2	-2
5	2	-10
5	3	5
6	3	-3
7	3	-11
7	4	4
8	4	-4
9	4	-12
9	5	3
10	5	-5
11	5	-13
11	6	2
12	6	-6
13	6	-14
13	7	1
14	7	-7

Obtain the phase image wrapped between -π and π from the second segmented fringe image

And the second area of the lookup table established by inequality is as follows:

m 1 (y)	m 2 (y)	m 2 (y)λ 2 -m 1 (y)λ 1
15	8	0
16	8	-8
16	9	7
17	9	-1
18	9	-9
18	10	6
19	10	-2
20	10	-10
20	11	5
twenty one	11	-3
twenty two	11	-11
twenty two	12	4
twenty three	12	-4
twenty four	12	-12
twenty four	13	3
25	13	-5
26	13	-13
26	14	2
27	14	-6
28	14	-14
28	15	1
29	15	-7

Obtain the wrapped phase image from -π to π from the third segmented fringe image

And the third area of the lookup table established by inequality is as follows:

m 1 (y)	m 2 (y)	m 2 (y)λ 2 -m 1 (y)λ 1
30	16	0
31	16	-8
31	17	7
32	17	-1
33	17	-9

For each segmented fringe pattern, calculate

The value of [m ₂ λ ₂ -m ₁ λ ₁ ] is rounded to the nearest whole number, and the row closest to the value is found in the corresponding area of the lookup table, and the m ₁ and m ₂ values of the same line are recorded; according to the absolute The calculation formula of the phase will be obtained

Values and the obtained m ₁ and m ₂ values are substituted into the above formula for phase expansion, and the absolute phase of the segmented fringe pattern is restored.

In the second embodiment of the present invention, as shown in FIG. 6, the dual fringe projection phase expansion device 100 based on color segmentation includes but is not limited to: an initialization module 110, a projection module 120, a segmentation module 130, and a table building operation module 140 and restore topography module 150.

Wherein, the initialization module 110 is used to design a projection fringe pattern by selecting a suitable fringe wavelength according to the resolution of the projector. The corresponding color fringe pattern is designed from the projector resolution and the projection fringe pattern. The color fringe pattern consists of at least two different colors. The color bars are arranged alternately;

The projection module 120 is used to project the color fringe pattern onto the object to be measured to obtain a deformed color image, and project the projected fringe pattern onto the object to be measured to obtain the deformed fringe pattern;

The segmentation module 130 is configured to perform at least two color area divisions on the deformed color image to obtain the corresponding deformed monochrome area, and divide the deformed fringe image into at least two segmented fringe images according to the position of the deformed monochrome area;

The table building operation module 140 is configured to obtain the wrapped phase image for each segmented fringe pattern and establish a lookup table for the corresponding region, and restore the absolute phase of the segmented fringe pattern from the wrapped phase image and the lookup table according to the absolute phase calculation formula;

The shape restoration module 150 is used to restore the three-dimensional shape of the object to be measured from the absolute phases of all the segmented fringe patterns.

It should be noted that, since the double fringe projection phase expansion device 100 based on color segmentation in this embodiment and the above-mentioned double fringe projection phase expansion method based on color segmentation are based on the same inventive concept, the corresponding content in the method embodiment The same applies to the embodiments of the device, and will not be described in detail here.

In the third embodiment of the present invention, as shown in FIG. 7, the double fringe projection phase unwrapping device 200 based on color segmentation can be any type of smart terminal, such as a mobile phone. , Tablet computers, personal computers, etc.

Specifically, the double fringe projection phase unwrapping device 200 based on color segmentation includes: one or more control processors 210 and a memory 220. In FIG. 7, one control processor 210 is taken as an example.

The control processor 210 and the memory 220 may be connected through a bus or in other ways. In FIG. 7, the connection through a bus is taken as an example.

As a non-transitory computer-readable storage medium, the memory 220 can be used to store non-transitory software programs, non-transitory computer-executable programs and modules, such as the double fringe projection phase expansion based on color segmentation in the embodiment of the present invention The program instructions/modules corresponding to the method, for example, the initialization module 110, the projection module 120, the segmentation module 130, the table creation calculation module 140, and the shape restoration module 150 shown in FIG. 6. The control processor 210 executes various functional applications and data processing of the double fringe projection phase unwrapping device 100 based on color segmentation by running the non-transitory software programs, instructions, and modules stored in the memory 220, thereby realizing the foregoing method embodiments Phase unwrapping method of double fringe projection based on color segmentation.

The memory 220 may include a storage program area and a storage data area. The storage program area can store an operating system and an application program required by at least one function; The created data, etc. In addition, the memory 220 may include a high-speed random access memory, and may also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory 220 may optionally include memories remotely provided with respect to the control processor 210, and these remote memories may be connected to the color segmentation-based double fringe projection phase unwrapping device 200 via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

The one or more modules are stored in the memory 220, and when executed by the one or more control processors 210, the double fringe projection phase expansion method based on color segmentation in the foregoing method embodiment is executed, for example, Perform the above-described method steps S100 to S500 in FIG. 1, method steps S110 to S120 in FIG. 2, method steps S310 to S340 in FIG. 3, method steps S331 to S332 in FIG. 4, and method steps in FIG. 5 S410 to S430 realize the functions of the modules 110-150 in FIG. 6.

An embodiment of the present invention also provides a computer-readable storage medium that stores computer-executable instructions, and the computer-executable instructions are executed by one or more control processors 210, for example, as shown in FIG. 7 One of the control processors 210 is executed to enable the one or more control processors 210 to execute the double fringe projection phase unwrapping method based on color segmentation in the foregoing method embodiment, for example, to execute the method steps in FIG. 1 described above S100 to S500, method steps S110 to S120 in FIG. 2, method steps S310 to S340 in FIG. 3, method steps S331 to S332 in FIG. 4, method steps S410 to S430 in FIG. 5, implements module 110 in FIG. 6 -150 features.

The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

Through the description of the above implementation manners, those skilled in the art can clearly understand that each implementation manner can be implemented by means of software plus a general hardware platform. Those skilled in the art can understand that all or part of the processes in the methods of the foregoing embodiments can be implemented by computer programs instructing relevant hardware. The programs can be stored in a computer readable storage medium. At this time, it may include the flow of the embodiment of the above-mentioned method. Wherein, the storage medium may be a magnetic disk, an optical disc, a read-only memory (Read Only Memory, ROM), or a random storage memory (Random AccesSS Memory, RAM), etc.

The above is a detailed description of the preferred implementation of the present invention, but the present invention is not limited to the above-mentioned embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. Equivalent modifications or replacements are all included in the scope defined by the claims of this application.

Claims (10)

1. The double fringe projection phase expansion method based on color segmentation is characterized in that it includes:

   Choose two fringe wavelengths to design the projection fringe pattern, which is composed of the color fringe pattern corresponding to the projector resolution and the projection fringe pattern design, and the color fringe pattern is composed of at least two color bars with different colors arranged alternately;

   Project the color fringe pattern onto the object to be measured to obtain a deformed color image, and project the projected fringe pattern onto the object to be measured to obtain a deformed fringe pattern;

   Perform at least two color area divisions on the deformed color image to obtain a corresponding deformed monochrome area, and divide the deformed fringe image into at least two segmented fringe images according to the position of the deformed monochrome area;

   For each segmented fringe image, obtain the wrapped phase image and establish a look-up table for the corresponding area, and restore the absolute phase of the segmented fringe image from the wrapped phase image and the look-up table according to the absolute phase calculation formula;

   The three-dimensional shape of the object to be measured is recovered from the absolute phase of all the segmented fringe patterns.
2. The double fringe projection phase expansion method based on color segmentation according to claim 1, wherein the corresponding color fringe pattern is designed by the projector resolution and the projection fringe pattern, and the color fringe pattern consists of at least two colors that are different from each other. The composition of the same color bars arranged alternately includes:

   The size of the color fringe pattern is the same as that of the projected fringe pattern;

   The color stripe diagram is designed by the design formula, the design formula is as follows:

   r ₂ =λ ₁ λ ₂ ,

   

   r ₁ =R-(n-1)r ₂ ,

   The number of color bars is n, R is the resolution of the projector, the color area of the color bar at the bottom is r ₁ , and the color area of the remaining color bars is r ₂ ,

   

   Indicates rounding up, λ ₁ and λ ₂ are the wavelengths of the projected fringes.
3. The double fringe projection phase expansion method based on color segmentation according to claim 2, characterized in that, the deformed color image is divided into at least two color regions to obtain the corresponding deformed monochromatic region, and the deformed monochromatic region is Location, the deformed fringe pattern is divided into at least two divided fringe patterns including:

   The number of divisions of the color area is the same as the number of color bars, the number of deformed monochrome areas is the same as the number of divisions of color areas, and the number of divided fringe patterns is the same as the number of deformed monochrome areas.
4. 5. The double fringe projection phase expansion method based on color segmentation according to claim 1, wherein said performing at least two color area divisions on the deformed color image to obtain the corresponding deformed monochrome area comprises:

   Steps to divide the color area:

   Set the color segmentation threshold δ, take any point a in the deformed color map, and find the approximate color D(z,a) of each point z and point a in the deformed color map. If D(z,a)≤δ, then point z Similar to the color of point a;

   All the points z whose colors are similar to the point a are composed to obtain an unprocessed divided area;

   Perform denoising processing on unprocessed divided areas to obtain deformed monochrome areas;

   Delete the deformed monochrome area in the deformed color map and replace the original deformed color map.
5. The double fringe projection phase expansion method based on color segmentation according to claim 4, wherein said calculating the color approximate value D(z, a) of each point z and point a of the deformed color image comprises:

   The calculation formula for the approximate color value D(z,a) of point z and point a is:

   

   The subscripts R, G, and B represent the RGB components of point z and point a, respectively.
6. The double fringe projection phase expansion method based on color segmentation according to claim 4, wherein the denoising processing on the unprocessed divided area comprises:

   Fill holes in untreated divided areas;

   Filter out the areas with smaller connected domains in the unprocessed divided areas.
7. The double fringe projection phase expansion method based on color segmentation according to claim 1, characterized in that, for each segmented fringe pattern, the wrapped phase image is obtained separately and the lookup table of the corresponding area is established, according to the absolute phase calculation formula , The absolute phase of the segmented fringe pattern recovered from the wrapped phase image and the look-up table includes:

   For each segmented fringe image, through fringe analysis technology, obtain the corresponding phase image that is distributed between -π and π

   

   Then the lookup table of the corresponding area is established by solving the inequality. The header of the established lookup table includes: m ₁ , m ₂ , m ₂ λ ₂ -m ₁ λ ₁ , where m ₁ , m _{2 are required} to restore the three absolute phases. Required fringe order,

   The inequality is as follows:

   

   0≤m ₁ ＜R/λ ₁ , 0≤m ₂ ＜R/λ ₂ ,

   Where λ ₁ , λ ₂ are the fringe wavelengths, m ₁ , m _{2 are the} order of the fringes,

   

   Is the wrapped phase map, and R is the resolution of the projector;

   Establish a one-to-one correspondence between the package phase image and the fringe order required for phase unwrapping according to the obtained package phase image and look-up table, and calculate

   

   The value of [m ₂ λ ₂ -m ₁ λ ₁ ] is rounded to the nearest whole number, and the closest row is found in the corresponding lookup table, and the m ₁ and m ₂ values of the same line are recorded;

   According to the calculation formula of absolute phase,

   

   Value and the obtained m ₁ , m ₂ values are substituted into the above formula for phase expansion, and the absolute phase of the segmented fringe pattern is restored,

   Absolute phase calculation formula:

   

   

   Among them, φ ₁ and φ ₂ are the absolute phases to be restored.
8. The dual fringe projection phase unwrapping device based on color segmentation is characterized in that it comprises:

   The initialization module is used to select two fringe wavelengths to design the projection fringe pattern, which is composed of the color fringe pattern corresponding to the projector resolution and the projection fringe pattern design, and the color fringe pattern is composed of at least two color bars with different colors alternately arranged;

   The projection module is used to project the color fringe pattern onto the object to be measured to obtain a deformed color image, and project the projected fringe pattern onto the object to be measured to obtain the deformed fringe pattern;

   The segmentation module is used to divide the deformed color image into at least two color regions and obtain the corresponding deformed monochrome region, and divide the deformed fringe image into at least two segmented fringe images according to the position of the deformed monochrome region;

   The table building operation module is used to obtain the wrapped phase image for each segmentation fringe image and establish a lookup table for the corresponding area. According to the absolute phase calculation formula, the absolute phase of the segmentation fringe image is restored from the wrapped phase image and the lookup table;

   The shape restoration module is used to restore the three-dimensional shape of the object to be measured from the absolute phase of all the segmented fringe patterns.
9. The double fringe projection phase unwrapping device based on color segmentation is characterized in that it includes:

   At least one processor; and,

   A memory communicatively connected with the at least one processor; wherein,

   The memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor, so that the at least one processor can execute any one of claims 1-7 Methods.
10. A computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to make a computer execute the method according to any one of claims 1-7 .

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