CN114166150B - Stripe reflection three-dimensional measurement method, system and storage medium - Google Patents
Stripe reflection three-dimensional measurement method, system and storage medium Download PDFInfo
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Abstract
A stripe reflection three-dimensional measuring method, system and storage medium, get the display image of many horizontal and longitudinal binary stripes according to the gray code; respectively acquiring a plurality of binary stripe reflection images; respectively extracting second edge lines of the plurality of horizontal and longitudinal binary stripe reflection images; carrying out Gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of a second edge line; acquiring an image coordinate of a point to be measured and a second gray code coordinate, and acquiring a display screen coordinate corresponding to the second gray code coordinate; acquiring gradient data of a point to be measured according to the display screen coordinates and the image coordinates; three-dimensional topographic data of the first surface is reconstructed. Therefore, the binary stripes are used for coding the coordinates of the displayed image, errors caused by the Gamma effect of a camera and a display with continuous phase modulation are immunized in principle, the states of the binary stripes are only 0 and 1, no intermediate state exists, the anti-noise capability is improved, and the three-dimensional reconstruction quality is improved.
Description
Technical Field
The invention relates to the technical field of three-dimensional measurement, in particular to a stripe reflection three-dimensional measurement method, a stripe reflection three-dimensional measurement system and a storage medium.
Background
The traditional fringe reflection three-dimensional measurement has higher requirements on the sine property and the contrast of phase fringes, and the high requirements on the sine property and the contrast have great difficulty in realizing in mirror-like workpieces (surfaces of semitransparent objects, light-color mirror-like surfaces and the like).
In the measurement, a camera is directly focused on the surface of an object to be measured, at the moment, a fringe image is blurred due to defocusing, so that the contrast of fringes is reduced, the signal-to-noise ratio is reduced, and the phase measurement precision is influenced.
In order to reduce the errors caused by low phase fringe quality, it is common practice to increase the number of steps of phase shift and to increase the exposure time or to increase the brightness of the display, for example, 8 steps of phase shift or even higher, and these parameters increase significantly to reduce the measurement rate or to increase the hardware cost greatly, and for the mirror-like surface with rich color, local overexposure or too dark occurs, resulting in undesirable reconstruction effect.
Disclosure of Invention
The invention mainly solves the technical problem that the existing fringe reflection three-dimensional measurement reconstruction effect is not ideal.
According to a first aspect, there is provided in an embodiment a fringe reflection three-dimensional measurement method, comprising:
obtaining a plurality of horizontal and longitudinal binary stripe display images according to gray code coding; the method comprises the steps that a plurality of binary stripe display images are used for determining the serial number of a first edge line of a stripe, and the first edge line comprises transverse edge lines and longitudinal edge lines; the first edge line forms a first gray code coordinate;
respectively acquiring a plurality of transverse and longitudinal binary stripe reflection images of a plurality of transverse and longitudinal binary stripe display images reflected by a first surface of an object to be detected;
respectively extracting second edge lines of the plurality of transverse and longitudinal binary fringe reflection images, wherein the second edge lines comprise transverse and longitudinal edge lines; carrying out Gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of a second edge line; the second edge line forms a second gray code coordinate, the second edge line corresponds to the first edge line, and the second gray code coordinate corresponds to the first gray code coordinate;
acquiring the image coordinate of the point to be measured and a second gray code coordinate in the binary stripe reflection image, and acquiring the display screen coordinate corresponding to the second gray code coordinate in the binary stripe display image;
acquiring gradient data of the point to be measured in a preset orthogonal direction according to the display screen coordinate and the image coordinate;
and reconstructing three-dimensional topography data of the first surface according to the gradient data.
According to a second aspect, there is provided in an embodiment a fringe reflection three-dimensional measurement system comprising:
the display is used for receiving the plurality of horizontal and longitudinal binary stripe display images sent by the processing terminal and displaying the binary stripe display images;
the object to be detected is used for reflecting the binary stripe display image to the shooting range of the camera;
the camera is used for acquiring an image of the first surface of the object to be detected and generating a binary fringe reflection image corresponding to the binary fringe display image;
the processing terminal is used for obtaining a plurality of horizontal and longitudinal binary stripe display images according to gray code coding, wherein the plurality of binary stripe display images are used for determining the sequence number of a first edge line of a stripe, and the first edge line comprises the horizontal and longitudinal edge lines; the first edge line forms a first gray code coordinate; sending a binary stripe display image to a display to obtain a binary stripe reflection image; respectively acquiring a plurality of transverse and longitudinal binary stripe reflection images of a plurality of transverse and longitudinal binary stripe display images reflected by a first surface of an object to be detected; respectively extracting second edge lines of the plurality of transverse and longitudinal binary fringe reflection images, wherein the second edge lines comprise transverse and longitudinal edge lines; carrying out Gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of a second edge line; the second edge line forms a second gray code coordinate, the second edge line corresponds to the first edge line, and the second gray code coordinate corresponds to the first gray code coordinate; acquiring the image coordinate of the point to be measured and a second gray code coordinate in the binary stripe reflection image, and acquiring the display screen coordinate corresponding to the second gray code coordinate in the binary stripe display image; acquiring gradient data of a point to be measured according to the display screen coordinates and the image coordinates; and reconstructing three-dimensional topography data of the first surface according to the gradient data.
According to a third aspect, an embodiment provides a computer-readable storage medium having a program stored thereon, the program being executable by a processor to implement the fringe reflection three-dimensional measurement method according to the first aspect.
According to the stripe reflection three-dimensional measurement method, the stripe reflection three-dimensional measurement system and the storage medium of the embodiment, a plurality of horizontal and longitudinal binary stripe display images are obtained according to gray code coding by the stripe reflection three-dimensional measurement method; respectively acquiring a plurality of transverse and longitudinal binary stripe reflection images of a plurality of transverse and longitudinal binary stripe display images reflected by a first surface of an object to be detected; respectively extracting second edge lines of the plurality of transverse and longitudinal binary fringe reflection images, wherein the second edge lines comprise transverse and longitudinal edge lines; carrying out Gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of a second edge line; the second edge line forms a second gray code coordinate, the second edge line corresponds to the first edge line, and the second gray code coordinate corresponds to the first gray code coordinate; acquiring an image coordinate of a point to be measured in the binary stripe reflection image and a second gray code coordinate, and acquiring a display screen coordinate corresponding to the second gray code coordinate in the binary stripe display image; acquiring gradient data of the point to be measured in a preset orthogonal direction according to the display screen coordinate and the image coordinate; and reconstructing three-dimensional shape data of the first surface according to the gradient data. Therefore, the binary stripes are used for coding the coordinates of the displayed image, errors caused by the Gamma effect of a camera and a display with continuous phase modulation are immunized in principle, the states of the binary stripes are only 0 and 1 without intermediate states, the anti-noise capability is improved theoretically, and the improvement of the three-dimensional reconstruction quality is realized.
Drawings
Fig. 1 is a schematic structural diagram of a fringe reflection three-dimensional measurement system according to an embodiment;
FIG. 2 is a flowchart of a fringe reflection three-dimensional measurement method according to an embodiment;
fig. 3 and 5 are schematic diagrams of a binary fringe display image/a binary fringe reflection image according to an embodiment;
FIGS. 4 and 6 are schematic diagrams of a first edge line/a second edge line according to an embodiment;
FIG. 7 is a diagram of first/second Gray code coordinates according to an exemplary embodiment;
FIG. 8 is a schematic diagram of a binary fringe display image and a binary fringe reflection image provided in one embodiment;
FIG. 9 is a schematic illustration of a positive sequence of reflected images and a negative sequence of reflected images provided by an embodiment;
FIG. 10 is a schematic illustration of a centerline provided by one embodiment;
fig. 11 is a schematic diagram of a fringe reflection three-dimensional measurement method according to an embodiment.
Reference numerals: 10-a display; 20-an object to be measured; 30-a camera; and 40, processing the terminal.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
In the traditional fringe reflection measurement, a phase shift method is used for carrying out phase coding on display coordinates, the measurement precision is influenced by phase precision, the phase precision is influenced by random noise and nonlinear errors, the largest source of the nonlinear errors is nonlinear response of a display and a camera, the nonlinear response is generally called as Gamma effect, the measurement precision of the phase shift method is easily interfered by low-frequency ambient light, the measurement environment has obvious requirements, and the popularization of the method in the field of online detection is limited.
In conventional fringe reflectometry, the LCD display projects sinusoidal fringes. The CCD camera records a virtual fringe image, in order to realize accurate measurement of the surface of an object to be measured, the CCD camera is directly focused on the surface of the object to be measured in an experiment, at the moment, the fringe image becomes fuzzy due to defocusing, so that the fringe contrast is reduced, the signal-to-noise ratio is reduced, and the phase measurement precision is influenced.
As shown in fig. 1 and fig. 2, the present invention provides a fringe reflection three-dimensional measurement method and system based on binary fringes, which theoretically eliminate the non-linear error caused by the Gamma effect of the display 10 and the camera 30, thereby improving the global measurement accuracy of the system.
In the present application, the binary stripe display image is an image displayed by the display 10, the pixel resolution of the image is determined according to the specific display 10, and the source of the image may be generated by the processing terminal 40 such as a display stripe controller or a computer, or may be a preset image that is sent to the display 10 through the processing terminal 40 for displaying.
In the present application, the binary fringe reflection image is an image obtained by shooting the first surface of the object 20 to be measured by the camera 30, and each binary fringe display image correspondingly forms one binary fringe reflection image.
In the present application, the binary stripe display image and the binary stripe reflection image are both stripe images, for example, the stripes are black and white stripes, and there are edge lines between the stripes, and the first edge line or the second edge line in the binary stripe display image and the binary stripe reflection image includes the edge line of the stripe, and may further include other lines generated based on the edge line of the stripe, such as a center line, a bisector. Corresponding to the transverse and longitudinal binary stripes, the first edge line and the second edge line are also provided with transverse and longitudinal edge lines correspondingly, and the edge lines are coded by Gray code coding to form Gray code coordinates correspondingly.
In the present application, any point in the binary stripe display image displayed on the display screen of the display 10 can be represented in the form of display screen coordinates, and is defined as the display screen coordinates. Each display pixel point in the display screen has a pixel coordinate, each pixel has a pixel size, and the display screen coordinate is the product of the pixel coordinate and the pixel size. Any point in the binary fringe reflection image captured and formed by the camera 30 can also represent the position in the binary fringe reflection image in the form of the pixel coordinate of the pixel point on the binary fringe reflection image, and is defined as the image coordinate.
The first embodiment is as follows:
referring to fig. 1, the present application provides a fringe-reflection three-dimensional measurement system, which includes a display 10, an object 20 to be measured, a camera 30 and a processing terminal 40.
The display 10 is configured to receive the plurality of horizontal and vertical binary stripe display images transmitted from the processing terminal 40, and display the binary stripe display images. Wherein, depending on the actual usage scenario, the display 10 may be a color display, and the corresponding camera 30 is a color camera.
The object 20 is configured to reflect the binary stripe display image to the shooting range of the camera 30, and the first surface of the object 20 is a mirror surface or a mirror-like surface.
The camera 30 is configured to acquire an image of the first surface of the object 20 to be measured, and generate a binary fringe reflection image corresponding to the binary fringe display image.
The processing terminal 40 is configured to obtain a plurality of horizontal and vertical binary stripe display images according to gray code coding, where the plurality of binary stripe display images are used to determine a sequence number of a first edge line of a stripe, where the first edge line includes horizontal and vertical edge lines; the first edge line constitutes a first gray code coordinate, and the display screen coordinate is obtained according to the conversion relation between the gray code and the decimal code and the pixel size of the display screen of the display 10; sending a binary stripe display image to the display 10 to obtain a binary stripe reflection image; respectively acquiring a plurality of transverse and longitudinal binary stripe reflection images of a plurality of transverse and longitudinal binary stripe display images reflected by a first surface of the object 20 to be measured; respectively extracting second edge lines of the multiple horizontal and longitudinal binary stripe reflection images, wherein the second edge lines comprise horizontal and longitudinal edge lines; carrying out Gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of a second edge line; the second edge line forms a second gray code coordinate, the second edge line corresponds to the first edge line, and the second gray code coordinate corresponds to the first gray code coordinate; acquiring a second gray code coordinate and an image coordinate of a point to be measured in the binary stripe reflection image, and acquiring a display screen coordinate corresponding to the second gray code coordinate in the binary stripe display image; according to the coordinates of the display screen and the image coordinates and in combination with parameters calibrated by the system, gradient data of the point to be measured in a preset orthogonal direction can be obtained; three-dimensional topographic data of the first surface may be reconstructed from the gradient data and the integral reconstruction algorithm. The processing terminal 40 may include a portion for generating a binary fringe display image, such as a display fringe controller or a computer generated by software, and may further include a computer for processing the image to reconstruct three-dimensional topographic data of the first surface.
Therefore, gray code coordinates of corresponding points of the binary fringe display image and the binary fringe reflection image can be directly obtained through fringe decoding, the pose relationship between the camera 30 and the reference plane and the pose relationship between the camera 40 and the display 40 can be determined according to geometric calibration of a fringe reflection measurement system, display screen coordinates and image coordinates are obtained, gradient information in the preset orthogonal direction of the object surface can be solved according to the deformation of fringe edges on the object surface, and three-dimensional appearance information of the object surface can be reconstructed through an integral reconstruction algorithm.
The following explains a specific process of the fringe reflection three-dimensional measurement method performed by the fringe reflection three-dimensional measurement system, as shown in fig. 2, including the following steps:
step 1: obtaining a plurality of horizontal and longitudinal binary stripe display images according to gray code coding; the method comprises the steps that a plurality of binary stripe display images are used for determining the serial number of a first edge line of a stripe, and the first edge line comprises transverse edge lines and longitudinal edge lines; the first edge line constitutes a first gray code coordinate.
As shown in fig. 3 and 5, taking four horizontal and vertical binary stripe display images as an example, according to the gray code encoding rule, 4 vertical binary stripe display images shown in fig. 3 can be obtained, each binary stripe display image includes black and white stripes, and for the convenience of observing the edge lines of the stripes, the black stripes are shown by shading in the drawings. For convenience of description, the binary stripe display image is used for illustration, and may be represented as a horizontal or vertical binary stripe display image, or may be represented as a horizontal or vertical binary stripe display image. For an RGB three-channel image, white fill may also represent the three colors red, green, and blue.
As shown in fig. 3 to 6, for each binary stripe display image, an edge line may be determined between a black stripe and a white stripe, and an edge line may also be determined between a black stripe and a white stripe between each two binary stripe display images, in this application, a first edge line may include edge lines determined in the above two cases, and a coordinate shown in fig. 7 may be constructed through the first edge line; each firstAnd the edge line can be written by a gray code for coding the serial number, and the coordinate system determined by the binary stripe display image is defined as a first gray code coordinate. As shown in the figure, the total of the four binary stripe display images contains 24-1-15 edges.
Therefore, for each binary stripe display image, each first edge line has a serial number, and the intersection point of the horizontal and vertical first edge lines can be represented by a first gray code coordinate. The gray code number may be obtained according to the following formula, where the number k is: k is 2n-i+((G0G1G2…Gi-1)2)10*2n-i+1N is the number of frames of the binary-stripe display image, i is the ordinal number of the binary-stripe display image, and i is 1,2 … n.
Because each binary stripe display image is displayed through the display 10, the spatial dimension of the binary stripe display image is determined by the dimension of the display screen of the display 10, the intersection point of two first edge lines in the horizontal direction and the vertical direction corresponds to a pixel coordinate position in the display 10, and then the display screen coordinate can be obtained according to the pixel dimension of the display 10, and for the determined binary stripe display image, the correspondence relationship between the display screen coordinate and the first gray code coordinate can be understood. That is, the first gray code coordinate can be obtained according to the conversion relationship between the gray code and the decimal code, and the display screen coordinate can be obtained according to the first gray code coordinate and the pixel size of the display screen.
Step 2: a plurality of horizontal and vertical binary stripe reflection images of the horizontal and vertical binary stripe display images reflected by the first surface of the object 20 to be measured are acquired, respectively.
Specifically, a preset binary stripe display image is displayed through the display 10 according to a gray code coding sequence, and when one binary stripe display image is displayed, the camera 30 is used for shooting the first surface of the object 20 to be detected once, so that the horizontal and longitudinal binary stripe reflection images are obtained. The binary stripe display images may be displayed in the order of gray code encoding, or the acquired binary stripe reflection images may be arranged in the order of gray code encoding.
And step 3: respectively extracting second edge lines of the plurality of transverse and longitudinal binary fringe reflection images, wherein the second edge lines comprise transverse and longitudinal edge lines; carrying out Gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of a second edge line; the second edge line forms a second gray code coordinate, the second edge line corresponds to the first edge line, and the second gray code coordinate corresponds to the first gray code coordinate.
The second edge line corresponds to the first edge line, the edge line included therein corresponds to the first edge line, and for each binary fringe reflection image, an edge line may be determined between a black fringe and a white fringe, and an edge line may also be determined between a black fringe and a white fringe between every two binary fringe reflection images.
As shown in fig. 9, the display 10 of the fringe reflective system reflected by the object 20 to be measured is often out of focus on the image of the camera 30, and the fringe spacing is too small, which results in edge blurring, thereby reducing the positioning accuracy, and for this problem,
in one possible implementation, the binary stripe display image may include a positive sequence display image (e.g., a in fig. 9) and a negative sequence display image (e.g., B in fig. 9); the binary fringe reflection images may include corresponding positive sequence reflection images and reverse sequence reflection images; the above-mentioned second edge lines of the plurality of horizontal and vertical binary fringe reflection images are extracted respectively, and include:
step 31: and determining the positions of the edge lines of the transverse stripes and the longitudinal stripes according to the transverse positive sequence reflected images and the transverse reverse sequence reflected images and the longitudinal positive sequence reflected images and the longitudinal reverse sequence reflected images respectively, wherein the second edge lines comprise the edge lines of the stripes.
Step 32: and extracting the position of a second edge line of the positive sequence reflection image or the reverse sequence reflection image.
Therefore, the embodiment provides an edge intersection point positioning method based on positive and negative stripes, and the edge intersection point positioning method can accurately position even if the stripes are blurred and overexposed. The specific implementation is as follows: the edge gray value of the positive sequence reflection image is gradually changed from 0-255, the edge gray value of the reverse sequence reflection image is gradually changed from 255-0, each two-value stripe display image has a corresponding reverse pattern, the gray value intersection point of the positive and the reverse stripes is a real edge point, as shown in fig. 9, the edge of the actual stripe shot by the camera 30 becomes fuzzy due to the defocusing effect, and the position of the edge line can be accurately positioned through the gray value intersection point of the positive and the reverse stripes. The edge lines of the transverse stripes and the edge lines of the longitudinal stripes can be obtained according to the transverse and longitudinal positive sequence reflected images and the transverse and longitudinal negative sequence reflected images respectively. As shown in fig. 9, the vertical forward-sequence display image and the vertical reverse-sequence display image can be used to obtain the edge lines of the vertical stripes.
In one possible implementation, as shown in fig. 10, the first edge line includes an edge line of a stripe of the binary stripe display image and a center line of the edge line of the stripe; the corresponding second edge line includes an edge line of the stripe of the binary stripe reflection image and a center line of the edge line of the stripe. Based on the above-mentioned edge line positioning using the binary stripes, this embodiment provides a technical solution for increasing the edge line density.
The extracting of the second edge lines of the plurality of horizontal and vertical binary fringe reflection images, respectively, may include:
step 33: and respectively extracting fringe lines of fringes in the horizontal and vertical binary fringe images.
Step 34: and obtaining the center line of the edge line of the stripe according to the edge line of the stripe, wherein the second edge line comprises the edge line of the stripe and the center line of the edge line of the stripe.
It can be seen that by using the center line as well as the edge line, the measurement point density measured by the reflectometry method (i.e. deflection) is improved. Based on the edge lines (including the first edge line and the second edge line) determined by the Gray code coding of the reflection measurement method, the center line positioning of the combination line movement is proposed, the point density is improved by 2 times, the 0.5 stripe interval is achieved, and the number of measurement points is enlarged by 4 times.
And 4, step 4: and acquiring the image coordinate of the point to be measured in the binary fringe reflection image and the second gray code coordinate, and acquiring the display screen coordinate corresponding to the second gray code coordinate in the binary fringe display image.
As shown in fig. 8, the binary fringe reflection image reflected by the first surface of the object 20 to be measured has a general outline related to the object 20 to be measured, and the position of the corresponding binary fringe display image cannot be known for any point to be measured of the binary fringe reflection image. Therefore, the application performs gray code decoding through a plurality of binary fringe reflection images in a gray code encoding mode, and can obtain the serial number of the second edge line, so that the second gray code coordinate of the intersection point of the horizontal and vertical second edge lines can be obtained. The second gray code coordinate corresponds to the first gray code coordinate, so that the display screen coordinate of the point to be measured of the binary fringe reflection image in the binary fringe display image can be obtained. The processing terminal 40 may directly obtain the pixel point position (i.e., image coordinate) of the point to be measured of the binary fringe reflection image in the binary fringe reflection image.
And 5: and acquiring gradient data of the point to be measured in the preset orthogonal direction by combining geometric calibration parameters of the fringe reflection system according to the display screen coordinates and the image coordinates. Specifically, obtaining a reference display screen coordinate according to an image coordinate and a geometric calibration parameter of a fringe reflection system; and acquiring gradient data of the point to be measured in the preset orthogonal direction according to the reference display screen coordinate and the display screen coordinate corresponding to the first gray code coordinate.
On the basis that the edge of the stripe in the binary stripe reflection image is straight and has no deformation under the condition that the first surface of the object 20 to be measured is a plane, the corresponding relationship between the image coordinate of any pixel point of the binary stripe reflection image and the display screen coordinate of the corresponding pixel point in the binary stripe display image can be determined through geometric calibration of the system, that is, the corresponding relationship between the image coordinate and the display screen coordinate can be determined. At this time, in the case where the first surface is a plane, display screen coordinates corresponding to the image coordinates are defined as reference display screen coordinates.
Specifically, assuming that the size of the display screen of the display 10 is 50cm × 50cm, each point of the binary stripe display image is represented by the display screen coordinates (X1cm, Y1cm) from the origin for a preset origin. For the binary fringe reflection image, a preset origin point is defined, and each point of the binary fringe reflection image can be represented by image coordinates (X2, Y2) from the origin point. It can be seen that for a fixed fringe reflection three-dimensional measurement system, the binary fringe display image of the display screen of the display 10 is reflected and then acquired by the camera, and the image coordinates of the binary fringe reflection image are determined values. For example, the image coordinates assume a point to be measured of (0.5 ), and in the case of a planar first surface, the ideal reference screen coordinates are (1cm ) in conjunction with geometric calibration of the system.
As shown in fig. 8, when the first surface of the object 20 to be measured is not flat, the corresponding relationship is changed, and the gradient change amount of the first surface, i.e. the gradient data, can be determined by calculating the change amount and combining with the geometric calibration of the system.
For example, as shown in fig. 11, the system geometric parameters and camera parameters have been calibrated, and the specific calculation process may be: encoding pixel coordinates of the display screen into a horizontal and vertical stripe sequence, after the horizontal and vertical stripes are projected on the display screen, reflecting the horizontal and vertical stripes to the camera through the first surface, after the camera collects a reflection pattern, decoding a binary stripe reflection image by the processing terminal to obtain the pixel coordinates of the display screen corresponding to each point to be measured in the image obtained by the camera, namely, when the image is in a reference plane, the display screen coordinates corresponding to the camera image coordinate point C are S1 (corresponding to the reference display screen coordinates). When the first surface of the object to be measured is a curved surface, the display screen coordinate S2 corresponding to the second gray code coordinate of the point C (corresponding to the display screen coordinate corresponding to the first gray code coordinate), the difference between S1 and S2 is the reflection variation caused by the gradient of the surface of the object to be measured, the incident light S1P, the reflected light PC, the incident light S2P of the first surface and the reflected light PC in the reference plane can be obtained by connecting the points, the angular bisector N1 of S1-P-C is the normal vector of the reference plane point P, the angular bisector N2 of S2-P-C is the normal vector of the point P according to the principles of space geometry and optical reflection, and the gradient value can be easily obtained by only solving the normal vector N2 of the first surface according to the principles of differential geometry.
That is to say, an ideal reference display screen coordinate can be obtained through the image coordinate, the normal vector evaluation of the corresponding reflected light is carried out with the display screen coordinate actually measured (decoded according to the gray code), and the gradient data of the point to be measured in the preset orthogonal direction is obtained.
Step 6: three-dimensional topographic data of the first surface is reconstructed from the gradient data.
After the gradient data are obtained, the three-dimensional topography data of the first surface can be reconstructed. For example, an integral reconstruction algorithm is used to integrate gradient data, such as the formula: z ═ gxdx+gydy。
In a possible implementation manner, in the binary stripe display image, each stripe width corresponds to a binary stripe display image with three RGB channels, and when a binary stripe display image with one stripe width is displayed, at least two binary stripe display images with different channels are simultaneously displayed. The stripe projection and the image acquisition of the display 10 are main factors for restricting the stripe reflection measurement beat, and besides improving the frame rate of the camera 30 and the refresh rate of the display 10, we can improve the measured morphology reconstruction beat by improving the stripe projection efficiency, so this embodiment proposes an RGB three-channel stripe projection method based on the color camera 30 and the color display 10, that is, R, G, B three channels of the display 10 project independent stripe patterns, so that three stripes can be projected onto the surface to be measured simultaneously in one projection period, and the three pictures are acquired by combining the color camera 30, because of the binary stripes, the method is not affected by the nonlinear difference between the channels, but the projection efficiency is obviously improved, and the projection time is reduced to the original 1/3.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by computer programs. When all or part of the functions of the above embodiments are implemented by a computer program, the program may be stored in a computer-readable storage medium, and the storage medium may include: a read only memory, a random access memory, a magnetic disk, an optical disk, a hard disk, etc., and the program is executed by a computer to realize the above functions. For example, the program may be stored in a memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above may be implemented. In addition, when all or part of the functions in the above embodiments are implemented by a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a removable hard disk, and may be downloaded or copied to a memory of a local device, or may be version-updated in a system of the local device, and when the program in the memory is executed by a processor, all or part of the functions in the above embodiments may be implemented.
The present invention has been described in terms of specific examples, which are provided to aid in understanding the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (10)
1. A fringe reflection three-dimensional measurement method is characterized by comprising the following steps:
obtaining a plurality of horizontal and longitudinal binary stripe display images according to gray code coding; wherein the plurality of binary stripe display images are used to determine a sequence number of a first edge line of a stripe, the first edge line comprising lateral and longitudinal edge lines; the first edge line forms a first gray code coordinate;
respectively acquiring a plurality of transverse and longitudinal binary stripe reflection images of the transverse and longitudinal binary stripe display images reflected by the first surface of the object to be detected;
respectively extracting second edge lines of the plurality of transverse and longitudinal binary stripe reflection images, wherein the second edge lines comprise transverse and longitudinal edge lines; performing gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of the second edge line; the second edge line forms a second gray code coordinate, the second edge line corresponds to the first edge line, and the second gray code coordinate corresponds to the first gray code coordinate;
acquiring the image coordinate of a point to be measured in the binary fringe reflection image and a second gray code coordinate, and acquiring the display screen coordinate corresponding to the second gray code coordinate in the binary fringe display image;
acquiring gradient data of the point to be measured in a preset orthogonal direction according to the display screen coordinate and the image coordinate;
and reconstructing three-dimensional topography data of the first surface according to the gradient data.
2. The fringe reflection three-dimensional measurement method of claim 1, wherein the first edge line comprises an edge line of a fringe and a center line of the edge line of the fringe.
3. The fringe reflection three-dimensional measuring method according to claim 2, wherein extracting the second edge lines of the plurality of horizontal and vertical bi-level fringe reflection images, respectively, comprises:
respectively extracting edge lines of stripes in the horizontal and longitudinal binary stripe images;
and obtaining the central line of the edge line of the stripe according to the edge line of the stripe, wherein the second edge line comprises the edge line of the stripe and the central line of the edge line of the stripe.
4. A fringe reflection three-dimensional measuring method according to any one of claims 1 to 3, wherein said binary fringe display image comprises a positive sequence display image and a negative sequence display image; the binary fringe reflection image comprises a corresponding positive sequence reflection image and a corresponding negative sequence reflection image; the extracting of the second edge lines of the plurality of horizontal and vertical binary fringe reflection images, respectively, includes:
determining the position of an edge line of the stripe according to the positive sequence reflection image and the negative sequence reflection image, wherein the second edge line comprises the edge line of the stripe;
and extracting the position of a second edge line of the positive sequence reflection image or the reverse sequence reflection image.
5. The fringe reflection three-dimensional measurement method according to claim 1, wherein each fringe width in the binary fringe display image corresponds to a binary fringe display image having three RGB channels, and when the binary fringe display image of one fringe width is displayed, the binary fringe display images of at least two different channels are simultaneously displayed.
6. A fringe reflection three-dimensional measurement system, comprising:
the display is used for receiving a plurality of horizontal and longitudinal binary stripe display images sent by the processing terminal and displaying the binary stripe display images;
the object to be detected is used for reflecting the binary stripe display image to the shooting range of the camera;
the camera is used for acquiring an image of the first surface of the object to be detected and generating a binary fringe reflection image corresponding to the binary fringe display image;
the processing terminal is used for obtaining a plurality of transverse and longitudinal binary stripe display images according to Gray code coding, wherein the plurality of binary stripe display images are used for determining the sequence number of a first edge line of a stripe, and the first edge line comprises a transverse edge line and a longitudinal edge line; the first edge line forms a first gray code coordinate; sending the binary stripe display image to the display to obtain a binary stripe reflection image; respectively acquiring a plurality of transverse and longitudinal binary stripe reflection images of the transverse and longitudinal binary stripe display images reflected by the first surface of the object to be detected; extracting second edge lines of the plurality of horizontal and vertical binary stripe reflection images respectively, wherein the second edge lines comprise horizontal edge lines and vertical edge lines; performing gray code decoding according to the plurality of horizontal and longitudinal binary fringe reflection images respectively to obtain the serial number of the second edge line; the second edge line forms a second gray code coordinate, the second edge line corresponds to the first edge line, and the second gray code coordinate corresponds to the first gray code coordinate; acquiring an image coordinate of a point to be measured in the binary fringe reflection image and a second gray code coordinate, and acquiring a display screen coordinate corresponding to the second gray code coordinate in the binary fringe display image; acquiring gradient data of the point to be measured in a preset orthogonal direction according to the display screen coordinate and the image coordinate; and reconstructing three-dimensional topography data of the first surface according to the gradient data.
7. The fringe reflection three-dimensional measurement system of claim 6, wherein the first edge line comprises an edge line of a fringe and a centerline of the edge line of the fringe.
8. The fringe-reflection three-dimensional measurement system of claim 7, wherein the processing terminal is configured to extract edge lines of the fringes in the horizontal and vertical binary fringe images, respectively; and obtaining the central line of the edge line of the stripe according to the edge line of the stripe, wherein the second edge line comprises the edge line of the stripe and the central line of the edge line of the stripe.
9. The fringe-reflective three-dimensional measurement system of claim 6, wherein each fringe width in the binary fringe display image corresponds to a binary fringe display image having three RGB channels, and wherein when the binary fringe display image of one fringe width is displayed, the binary fringe display images of at least two different channels are simultaneously displayed.
10. A computer-readable storage medium, characterized in that the medium has a program stored thereon, the program being executable by a processor to implement the fringe reflection three-dimensional measurement method according to any one of claims 1-5.
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