A position compensation method and system based on an array-type feature pattern

Abstract

The present application provides a position compensation method and system based on an array of feature patterns. The method includes: selecting four peripheral reference dots in a calibration plate with a reference dot and a reference circle dot, and connecting them in sequence to form a reference quadrilateral; calculating the distance from the reference circle dot corresponding to a row or a column to the corresponding reference side; statistically determining the maximum value of the distances as a threshold; solving an affine transformation matrix according to the four peripheral reference dots and the corresponding reference points of the workpiece; performing an affine transformation on the contours of all the reference circle dots according to the obtained matrix to obtain an ellipse fitting center, and performing a fitting based on a circle contour on the contour trajectory after the affine transformation to obtain a circle fitting center; performing position compensation according to the threshold, and the ellipse fitting center and the circle fitting center to remove positioning errors and obtain the coordinates of the circle fitting center of the calibration plate; remapping the reference circle dots after position compensation according to the affine transformation matrix to obtain the compensated actual positions. In the present application, the calibration accuracy of the camera is improved.

Description

Technical Field

[0001] This application relates to the technical field of computer vision - camera calibration, and particularly to a position compensation method and system based on an array - type feature pattern. Background Art

[0002] Computer vision is a discipline about how to use cameras and computers to obtain the data and information of the objects we need in the captured images, and camera calibration is to establish the mapping relationship between the pixel positions in the camera image and the corresponding objects in the world coordinate system. Therefore, camera calibration is the basis of computer vision, and the accuracy of the calibration result will directly affect the positioning accuracy of the entire vision system.

[0003] Camera calibration mainly consists of three aspects: image acquisition, feature point extraction, and camera calibration.

[0004] In camera calibration technology, feature point extraction is mainly divided into two categories according to the different forms of the calibration board: sub - pixel corner position extraction based on checkerboards and center position extraction based on circular calibration boards. The circular calibration board is superior to the checkerboard calibration board in terms of anti - noise and anti - blurring, and can avoid the reduction of detection accuracy caused by pixel changes at the corners of the checkerboard. Therefore, the circular calibration board is usually selected in occasions with high - precision requirements.

[0005] When extracting feature points from a circular calibration board, it is necessary to perform fitting based on circles, ellipses or other methods according to the feature contour to obtain the center point of the contour. The center point is directly used as a feature point and brought into the camera calibration algorithm to obtain the internal and external parameters of the camera and the distortion coefficients. Such a processing process determines that the positioning accuracy of the feature points will overly depend on the accuracy of graphic fitting. And when the calibration board has a pose change and there is an angle between its plane and the image plane of the camera, affected by the perspective transformation, the positioning accuracy of its feature points will decrease. Summary of the Invention

[0006] Based on the above - mentioned purpose, this application proposes a position compensation method based on an array - type feature pattern, including:

[0007] Select four peripheral reference dots in a calibration board with reference dots and reference circles, and connect them in sequence to form a reference quadrilateral;

[0008] Calculate the distance from the reference circles in the corresponding row or column to the corresponding reference sides;

[0009] Statistical maximum value of the distances as a threshold;

[0010] Solve the affine transformation matrix according to the four peripheral reference dots and the corresponding reference points of the workpiece;

[0011] Perform an affine transformation on the contours of all reference dots according to the obtained matrix, obtain the ellipse fitting center, and perform a circle contour-based fitting on the contour trajectory after the affine transformation to obtain the circle fitting center;

[0012] According to the threshold, as well as the ellipse fitting center and the circle fitting center, perform position compensation to remove the positioning error and obtain the coordinates of the circle fitting center of the calibration plate;

[0013] Remap the reference dots after position compensation according to the affine transformation matrix to obtain the compensated actual positions.

[0014] Furthermore, the calibration plate includes:

[0015] Five reference dots and multiple reference dots, and the dot regions and the background color are opposite colors; among them,

[0016] Among the five reference dots, the connections of four of the outer reference dots form a quadrilateral with a perspective relationship, serving as the reference for all reference dots, and the outer reference dots are arranged in the central area of the calibration plate; the fifth reference point is located in the middle of the two lower outer reference dots and is set as the origin of the calibration plate coordinate system, used to record the pose information of the calibration plate and the sorting information of the reference dots.

[0017] Furthermore, the reference dots on the calibration plate are arranged in an array, with each row parallel, each column parallel, perpendicular to each other between rows and columns, and at equal distances between reference dots.

[0018] Furthermore, use the method of vector dot product to calculate the distance from the reference dots in the corresponding row or column to the corresponding reference edge.

[0019] Furthermore, the formula for solving the affine transformation matrix is as follows:

[0020]

[0021] Where a i , {i = 1, 2, 3, 4} are rotation parameters, t x , t y are translation parameters, x, y are the original image positions, and x′, y′ are the positions after the affine transformation.

[0022] Furthermore, the position compensation includes position compensation based on distance weights or position compensation based on the shortest distance.

[0023] Furthermore, the position compensation based on distance weights includes:

[0024]

[0025] where T is the threshold value, and e i is the center coordinate of the ellipse fitting, and c i is the center coordinate of the circle fitting. dis represents the distance between two points, and d i represents the center coordinate of the reference point of the calibration plate.

[0026] According to another aspect of the present application, there is also provided a position compensation system based on an array feature pattern, including:

[0027] A reference selection module for selecting four peripheral reference dots in a calibration plate with reference dots and fiducial dots, and connecting them in sequence to form a reference quadrilateral;

[0028] A distance calculation module for calculating the distance from the reference dots in the corresponding row or column to the corresponding reference side;

[0029] A threshold statistics module for statistically calculating the maximum value of the distances as the threshold value;

[0030] A matrix solution module for solving an affine transformation matrix according to the four peripheral reference dots and the corresponding reference points of the workpiece;

[0031] A center fitting module for performing an affine transformation on the contours of all the reference dots according to the obtained matrix, obtaining an ellipse fitting center, and performing a circle contour-based fitting on the contour trajectory after the affine transformation to obtain a circle fitting center;

[0032] A position compensation module for performing position compensation according to the threshold value, and the ellipse fitting center and the circle fitting center, removing the positioning error, and obtaining the calibration plate circle fitting center coordinate;

[0033] A remapping module for remapping the reference dots after position compensation according to the affine transformation matrix to obtain the compensated actual position.

[0034] Generally speaking, the advantages of the present application and the experience brought to users are as follows:

[0035] The position compensation method involved in the present application improves the calibration accuracy of the camera by compensating for the positioning error of the center point of the graphic contour caused by the pose change of the calibration plate. Brief Description of the Drawings

[0036] In the drawings, unless otherwise specified, the same reference numerals throughout the several views refer to the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed according to the present application, and should not be regarded as limiting the scope of the present application.

[0037] Appendix Figure 1Flowchart of a position compensation method based on an array of feature patterns according to the present application;

[0038] Appendix Figure 2 Schematic diagram of the selection of the reference benchmark according to the present application;

[0039] Appendix Figure 3 Schematic diagram of solving the distance from a point to a line based on the vector method according to the present application;

[0040] Appendix Figure 4 Schematic diagram of the threshold range according to the present application;

[0041] Appendix Figure 5 Schematic diagram of the position compensation of the reference origin point according to the present application;

[0042] Appendix Figure 6 Schematic diagram of the actual position of the reference origin point after remapping according to the present application;

[0043] Appendix Figure 7 Structural diagram of a position compensation system based on an array of feature patterns according to the present application;

[0044] Appendix Figure 8 Schematic diagram of the structure of an electronic device provided by an embodiment of the present application;

[0045] Appendix Figure 9 Schematic diagram of a storage medium provided by an embodiment of the present application. Detailed implementation manners

[0046] The present application will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the related invention, rather than limiting the invention. Additionally, it should be noted that for the sake of description, only parts related to the relevant invention are shown in the drawings.

[0047] It should be noted that, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the drawings and embodiments.

[0048] In the present application, the distance is calibrated with an array of circles. Four reference points are selected on the calibration board, and these four reference points are connected in sequence as the reference baseline. The threshold of each row (column) is statistically obtained from the distance from the reference origin point of each row (column) to the baseline; according to the obtained threshold, projective transformation is used to perform position compensation on each reference origin point in the front view, so as to obtain a more accurate position of the reference origin point of the calibration board.

[0049] (It should be noted that the protection scope of the present application is not limited to the type of the calibration board and the selection of the reference point position, nor is it limited to the arrangement mode, size, shape, color, etc. of the pattern.)

[0050] Example 1: A circular calibration board with a reference.

[0051] As Figure 1 shown in the figure is the illustration of the calibration board used in this application. The calibration board consists of the following aspects: It is composed of 5 reference dots and several reference dots (the number and shape formed by the arrangement of the reference dots are not restricted), and the dot area and the background color are opposite colors to each other. Among the 5 reference dots, the connection lines of 4 of the outer reference dots can form a quadrilateral with a perspective relationship, which is the reference for all reference dots and is arranged in the central area of the calibration board. And the fifth reference point is set as the origin of the calibration board coordinate system, which is used to record the pose information of the calibration board and the sorting information of the reference dots. And the reference dots on the calibration board are arranged in an array, with each row (column) parallel and perpendicular to each other between rows and columns, and the reference dots are spaced at equal distances from each other.

[0052] Example 2: A position compensation method based on an array feature pattern, as Figure 2 shown, includes the following steps:

[0053] Step1: As Figure 1 shown, select 4 outer reference dots 1, 3, 4, 5 and connect them in sequence to form a reference quadrilateral.

[0054] Step2: As Figure 3 shown, use the method of vector dot product to calculate the distance from the reference dots in the corresponding row (column) to the corresponding reference edge;

[0055]

[0056]

[0057] In the formula, AB is a reference edge of the reference quadrilateral, P is the center of the ellipse fitting, C is the foot of the perpendicular from P to AB. d is the length of the line segment AC, h is the height from point P to the line segment AC, that is, the distance from the reference dots in the corresponding row (column) to the corresponding reference edge.

[0058] Step3: As Figure 4 shown, count the maximum value of the distance h from the reference dots in the corresponding row (column) to the corresponding reference edge as the threshold T;

[0059] T = max(h), {i = 1, 2, …, n}

[0060] where h is the distance from the center point of the ellipse in each row (column) to the reference baseline of that row (column).

[0061] Step4: Solve the affine transformation matrix according to the four reference dots selected in Step1 and the corresponding reference points of the workpiece

[0062]

[0063] Among them, a i , {i = 1, 2, 3, 4} are rotation parameters, t x , t y is the translation parameter, x, y are the positions of the original image, and x′, y′ are the positions after affine transformation.

[0064] Step5: Perform affine transformation on the contours of all reference circular points according to the matrix obtained in step4, and perform fitting based on the circular contour on the contour trajectory after affine transformation, see Figure 5 .

[0065] Step6: As Figure 6 shown, according to the threshold calculated in Step3, comprehensively compensate the positions of the ellipse fitting center (denoted as e i ) and the circle fitting center (denoted as c i ) obtained by projective transformation in Step5 to remove the positioning error, so as to obtain the relatively accurate calibration plate circle fitting center coordinates (denoted as d i ). The core algorithms can be divided into two categories:

[0066] 1. Position compensation based on distance weight

[0067]

[0068] In the formula, d i is the center coordinate of the calibration plate reference point, e i is the ellipse fitting center coordinate, c i is the circle fitting center coordinate, T i is the threshold, and dis() is to solve the distance between two points.

[0069] 2. Position compensation based on the shortest distance

[0070] Connect the ellipse center e i and the circle center c i , solve the foot of the perpendicular from the ideal point i i of the calibration plate reference circular point to the line segment e i c i , which is the center coordinate d i of the calibration plate reference point.

[0071] d i = min(i i , |e i - c i |)

[0072] In the formula, d i is the center coordinate of the calibration plate reference point, ii is the ideal position of the calibration plate reference point without distortion and positioning error, e i is the center coordinate of the ellipse fitting, c i is the center coordinate of the circle fitting.

[0073] Step7: Remap the reference dot points after position compensation according to the affine transformation matrix in Step4 to obtain the compensated actual position.

[0074] Example 3, A position compensation system based on an array of feature patterns.

[0075] The embodiment of the present application provides a position compensation system based on an array of feature patterns. This system is used to execute the position compensation method based on an array of feature patterns described in the above embodiment, as Figure 7 shown, this system includes:

[0076] A reference selection module 501, which is used to select four peripheral reference dot points in a calibration plate with reference dot points and reference dots, and connect them in sequence to form a reference quadrilateral;

[0077] A distance calculation module 502, which is used to calculate the distance from the reference dot points in the corresponding row or column to the corresponding reference edge;

[0078] A threshold statistics module 503, which is used to statistically calculate the maximum value of the distance as the threshold;

[0079] A matrix solving module 504, which is used to solve the affine transformation matrix according to the four peripheral reference dot points and the corresponding reference points of the workpiece;

[0080] A center fitting module 505, which is used to perform an affine transformation on the contours of all reference dot points according to the solved matrix to obtain the ellipse fitting center, and perform a circle contour-based fitting on the contour trajectory after the affine transformation to obtain the circle fitting center;

[0081] A position compensation module 506, which is used to perform position compensation according to the threshold, and the ellipse fitting center and the circle fitting center, remove the positioning error, and obtain the circle fitting center coordinates of the calibration plate;

[0082] A remapping module 507, which is used to remap the reference dot points after position compensation according to the affine transformation matrix to obtain the compensated actual position.

[0083] The position compensation system based on an array of feature patterns provided by the above embodiment of the present application and the position compensation method based on an array of feature patterns provided by the embodiment of the present application are based on the same inventive concept and have the same beneficial effects as the methods adopted, run or implemented by the application programs stored therein.

[0084] Embodiments of the present application also provide an electronic device corresponding to the position compensation method and calibration method based on an array feature pattern provided in the foregoing embodiments to execute the position compensation method and calibration method based on an array feature pattern. Embodiments of the present application are not limited thereto.

[0085] Please refer to Figure 8 , which shows a schematic diagram of an electronic device provided in some embodiments of the present application. As Figure 8 shown, the electronic device 2 includes: a processor 200, a memory 201, a bus 202, and a communication interface 203. The processor 200, the communication interface 203, and the memory 201 are connected through the bus 202. A computer program that can run on the processor 200 is stored in the memory 201. When the processor 200 runs the computer program, it executes the position compensation method and calibration method based on an array feature pattern provided in any of the foregoing embodiments of the present application.

[0086] Among them, the memory 201 may include a high-speed random access memory (RAM: Random Access Memory), and may also include a non-volatile memory, such as at least one disk memory. Through at least one communication interface 203 (which may be wired or wireless), a communication connection between the system network element and at least one other network element can be realized, and the Internet, a wide area network, a local area network, a metropolitan area network, etc. can be used.

[0087] The bus 202 may be an ISA bus, a PCI bus, an EISA bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. Among them, the memory 201 is used to store a program. After receiving an execution instruction, the processor 200 executes the program. The position compensation method based on an array feature pattern disclosed in any of the foregoing embodiments of the present application can be applied to the processor 200 or implemented by the processor 200.

[0088] The processor 200 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit of the hardware in the processor 200 or the instructions in the form of software. The above-mentioned processor 200 may be a general-purpose processor, including a central processing unit (CPU for short), a network processor (NP for short), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed and completed by the hardware decoding processor, or executed and completed by a combination of the hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory 201, and the processor 200 reads the information in the memory 201 and combines its hardware to complete the steps of the above method.

[0089] The electronic device provided in the embodiments of the present application and the position compensation method based on the array-type feature pattern provided in the embodiments of the present application are based on the same inventive concept and have the same beneficial effects as the method adopted, run, or implemented by it.

[0090] The embodiments of the present application also provide a computer-readable storage medium corresponding to the position compensation method based on the array-type feature pattern provided in the foregoing embodiments. Please refer to Figure 9 , which shows that the computer-readable storage medium is an optical disc 30, on which a computer program (i.e., a program product) is stored. When the computer program is run by a processor, it will execute the position compensation method and the calibration method provided in any of the foregoing embodiments.

[0091] It should be noted that examples of the computer-readable storage medium may also include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or other optical and magnetic storage media, which will not be elaborated here one by one.

[0092] The computer-readable storage medium provided by the above embodiments of the present application and the position compensation method and calibration method based on the array-type feature pattern provided by the embodiments of the present application are based on the same inventive concept and have the same beneficial effects as the methods adopted, run or implemented by the application programs stored therein.

[0093] It should be noted that:

[0094] The algorithms and displays provided herein are not inherently related to any particular computer, virtual system, or other device. Various general-purpose systems can also be used in conjunction with the teachings provided herein. The structure required to construct such a system will be apparent from the above description. In addition, the present application is not directed to any particular programming language. It should be understood that the content of the present application described herein can be implemented using various programming languages, and the description of a particular language above is for the purpose of disclosing the best mode of the present application.

[0095] In the specification provided herein, a large number of specific details are set forth. However, it can be understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures, and technologies have not been shown in detail so as not to obscure the understanding of this specification.

[0096] Similarly, it should be understood that, in order to streamline the present application and assist in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting an intention that the claimed present application requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, the inventive aspects lie in less than all the features of the single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate embodiment of the present application.

[0097] Those skilled in the art can understand that the modules in the devices in the embodiments can be adaptively changed and set in one or more devices different from the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and in addition, they can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and / or processes or units are mutually exclusive, any combination can be adopted to combine all the features disclosed in this specification (including the accompanying claims, abstract and drawings) and all the processes or units of any method or device so disclosed. Unless otherwise clearly stated, each feature disclosed in this specification (including the accompanying claims, abstract and drawings) can be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0098] In addition, those skilled in the art can understand that although some of the embodiments described herein include certain features included in other embodiments rather than other features, the combination of the features of different embodiments means that it is within the scope of this application and forms different embodiments. For example, in the following claims, any one of the claimed embodiments can be used in any combination.

[0099] Each component embodiment of the present application can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art should understand that a microprocessor or a digital signal processor (DSP) can be used in practice to implement some or all of the functions of some or all of the components in the virtual machine creation system according to the embodiments of the present application. The present application can also be implemented as a device or system program (such as a computer program and a computer program product) for executing part or all of the methods described herein. Such a program for implementing the present application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0100] It should be noted that the above embodiments are illustrative of the present application rather than restrictive thereof, and those skilled in the art can design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The present application can be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In the unit claims listing several systems, several of these systems can be embodied by the same item of hardware. The use of the words first, second, and third, etc. does not denote any order. These words can be interpreted as names.

[0101] As described above, the specific embodiments of the present application are merely illustrative, but the protection scope of the present application is not limited thereto. Those skilled in the art can easily conceive various changes or substitutions within the technical scope disclosed in the present application, and all of these should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A position compensation method based on an array of characteristic patterns, characterized in that, Including: Select four peripheral fiducial dots in a calibration board with a fiducial dot and a reference dot, and connect them in sequence to form a fiducial quadrilateral; Calculate the distance from the reference dot in the corresponding row or column to the corresponding fiducial edge; Statistically determine the maximum value of the distances as the threshold; Solve the affine transformation matrix according to the four peripheral fiducial dots of the calibration board and the corresponding fiducial points of the workpiece; Perform an affine transformation on the contours of all the reference dots according to the obtained matrix, obtain the ellipse fitting center, and perform a circle contour-based fitting on the contour trajectory after the affine transformation to obtain the circle fitting center; Perform position compensation according to the threshold, and the ellipse fitting center and the circle fitting center, remove the positioning error, and obtain the coordinates of the circle fitting center of the calibration board; Remap the reference dots after position compensation according to the affine transformation matrix to obtain the compensated actual position; The calibration board includes: Five fiducial dots and multiple reference dots, and the dot areas and the background color are opposite to each other; among them, Among the five fiducial dots, the connection of four peripheral fiducial dots forms a quadrilateral with a perspective relationship, serving as the reference for all reference dots, and the peripheral fiducial dots are arranged in the central area of the calibration board; the fifth fiducial point is located in the middle position between the two lower peripheral fiducial dots and is set as the origin of the calibration board coordinate system for recording the pose information of the calibration board and the sorting information of the reference dots; The position compensation includes position compensation based on distance weights, including: Among them, is the said threshold value, is the center coordinate of the ellipse fitting, is the center coordinate of the circle fitting, dis represents the distance between two points, represents the center coordinate of the calibration plate reference point; The reference dots on the calibration board are arranged in an array, each row is parallel, each column is parallel, the rows and columns are perpendicular to each other, and the reference dots are spaced at equal distances from each other.

2. The method according to claim 1, characterized in that, Use the method of vector dot product to calculate the distance from the reference dot in the corresponding row or column to the corresponding fiducial edge.

3. The method according to claim 1, characterized in that, The formula for solving the affine transformation matrix is as follows: is the rotation parameter, is the translation parameter, is the position of the original image, is the position after affine transformation, and z is the coordinate in the axis direction perpendicular to the image plane.

4. A position compensation system based on an array of characteristic patterns, using the method according to any one of claims 1-3, characterized in that, Including: A fiducial selection module for selecting four peripheral fiducial dots in a calibration board with a fiducial dot and a reference dot, and connecting them in sequence to form a fiducial quadrilateral; A distance calculation module for calculating the distance from the reference dot in the corresponding row or column to the corresponding fiducial edge; A threshold statistics module for statistically determining the maximum value of the distances as the threshold; A matrix solution module for solving the affine transformation matrix according to the four peripheral fiducial dots of the calibration board and the corresponding fiducial points of the workpiece; A center fitting module for performing an affine transformation on the contours of all the reference dots according to the obtained matrix, obtaining the ellipse fitting center, and performing a circle contour-based fitting on the contour trajectory after the affine transformation to obtain the circle fitting center; A position compensation module for performing position compensation according to the threshold, and the ellipse fitting center and the circle fitting center, removing the positioning error, and obtaining the coordinates of the circle fitting center of the calibration board; A remapping module for remapping the reference dots after position compensation according to the affine transformation matrix to obtain the compensated actual position.

5. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor runs the computer program to implement the method according to any one of claims 1-3.

6. A computer-readable storage medium, on which a computer program is stored, characterized in that, The program is executed by the processor to implement the method according to any one of claims 1-3.

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