Checkerboard angular point automatic extraction method, system and device and medium

Abstract

The invention provides a checkerboard angular point automatic extraction method, system and device and a medium, and the method comprises the steps: obtaining a checkerboard image, the checkerboard image comprises at least one marking pattern, and the marking pattern is located in a checkerboard region of the checkerboard image; identifying a marked graph area in the checkerboard image, and further extracting position information of a marked graph in the checkerboard image; determining the positions of each black lattice area and each white lattice area according to the position information of the marked pattern; and determining the position of each checkerboard angular point in the checkerboard image according to the position information of each black checkerboard area and each white checkerboard area. According to the invention, the mark pattern is arranged on the checkerboard image, and the positions of each black lattice area and each white lattice area are determined in sequence through extraction of the mark image, so that extraction of the position of each checkerboard corner is realized, the problem that when the whole camera visual field is filled with the checkerboard image, the recognition of the corner is often wrong is avoided, and the recognition accuracy is improved. Rapid calibration of the camera is realized.

Description

Background Art

[0002] In the image measurement process and machine vision applications, in order to determine the relationship between the three-dimensional geometric position of a point on the surface of a spatial object and its corresponding point in the image, a geometric model of camera imaging must be established. These geometric model parameters are the camera parameters. Under most conditions, these parameters must be obtained through experiments and calculations. The process of solving the parameters is called camera calibration.

[0003] When calibrating a camera, a calibration plate is usually used. By shooting a flat plate with a fixed-pitch pattern array and calculating it with a calibration algorithm, the geometric model of the camera can be obtained, thereby obtaining high-precision measurement and reconstruction results.

[0004] Commonly used calibration plates include checkerboard calibration plates, circular mark point calibration plates, QR code calibration plates, and coded mark point calibration plates. When using a checkerboard calibration plate for camera calibration, the corner points of the captured checkerboard image need to be manually marked in the prior art, or when the number of grids in the checkerboard image is small and only occupies part of the camera's field of view, the corner points can be detected by image recognition to identify the corner points of the checkerboard image. However, when the checkerboard image fills the entire camera's field of view, errors often occur when identifying the corner points, so that each grid area in the checkerboard image cannot be labeled. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a method, system, device and medium for automatically extracting checkerboard corner points.

[0006] The method for automatically extracting chessboard corner points provided by the present invention comprises the following steps:

[0007] Step S1: Acquire a checkerboard image, wherein the checkerboard image includes at least one marking graphic, and the marking graphic is located in a square area of ​​the checkerboard image;

[0008] Step S2: identifying the marked graphic area in the chessboard image, and then extracting the position information of the marked graphic in the chessboard image;

[0009] Step S3: determining the position of each of the black grid area and the white grid area according to the position information of the marking pattern;

[0010] Step S4: determining the position of each checkerboard corner point in the checkerboard image according to the position information of each black checkerboard area and the white checkerboard area.

[0011] Preferably, step S1 comprises the following steps:

[0012] Step S101: obtaining a checkerboard image, and if the image is a multi-channel image, converting the checkerboard image into a first checkerboard grayscale image;

[0013] Step S102: downsampling or upsampling according to the resolution of the first chessboard grayscale image to generate a second chessboard grayscale image;

[0014] Step S103: binarizing the second checkerboard grayscale image to generate the checkerboard image.

[0015] Preferably, step S2 comprises the following steps:

[0016] Step S201: corroding each white grid area in the checkerboard image so that any adjacent white grid areas in the checkerboard image are separated from each other, thereby fitting a first contour of each white grid area;

[0017] Step S202: corroding each black grid area in the checkerboard image so that any adjacent black grid areas in the checkerboard image are separated from each other, thereby fitting a second contour of each black grid area;

[0018] Step S203: identifying the position of the marking graphic according to the topological relationship between the marking graphic and the first contour or the second contour.

[0019] Preferably, step S3 comprises the following steps:

[0020] Step S301: according to the position information of the marking graphic, four white grid areas and four black grid areas closest to the center of the marking graphic are found through the nearest neighbor relationship, and the four white grid areas and four black grid areas are used as a subgrid;

[0021] Step S302: Determine a grid area adjacent to the seed grid by expanding outwards from the seed grid through a cross ratio method, and then use the seed grid and the grid area adjacent to the seed grid as another sub-grid;

[0022] Step S303: Step S303: Repeat step S302 to continuously expand the seed grid to determine the position of each of the black grid areas and the white grid areas.

[0023] Preferably, step S4 comprises the following steps:

[0024] Step S401: determining the position of each checkerboard corner point of the checkerboard area where the mark pattern is located according to four white checkerboard areas and four black checkerboard areas closest to the center of the mark pattern;

[0025] Step S402: Whenever a sub-grid is generated, the position of each chessboard grid corner point inside the seed grid is determined according to each black grid area and the white grid area in the seed grid;

[0026] Step S403: As the seed grid expands, the position of each checkerboard corner point of the checkerboard image is determined in sequence.

[0027] Preferably, the method further comprises any one or more of the following steps:

[0028] Step S5: verifying the position area of ​​each chessboard corner point to determine whether the position area is the position area of ​​the chessboard corner point;

[0029] Step S6: extracting sub-pixels of the position area of ​​each checkerboard corner point, and adjusting the position of each checkerboard corner point according to the sub-pixels of the position area of ​​each checkerboard corner point;

[0030] Step S7: generating two-dimensional coordinates of the checkerboard corner points according to the positions of the checkerboard corner points, and generating three-dimensional coordinates of the checkerboard corner points according to the two-dimensional coordinates of the checkerboard corner points.

[0031] Preferably, the marking graphic includes any one or more of the following graphics:

[0032] - round shape;

[0033] - Ring-shaped;

[0034] -triangle;

[0035] -rectangle;

[0036] - Arbitrary polygons.

[0037] The automatic extraction system of chessboard corner points provided by the present invention is used to implement the automatic extraction method of chessboard corner points, and comprises:

[0038] An image acquisition module, used for acquiring a checkerboard image, wherein the checkerboard image includes at least one marking graphic, and the marking graphic is located in a square area of ​​the checkerboard image;

[0039] A marking pattern extraction module, used to identify the marking pattern area in the checkerboard image, and then extract the position information of the marking pattern in the checkerboard image;

[0040] A grid area recognition module, used to determine the position of each of the black grid area and the white grid area according to the position information of the marking pattern;

[0041] The corner point extraction module is used to determine the position of each checkerboard corner point in the checkerboard image according to the position information of each black checkerboard area and the white checkerboard area.

[0042] The chessboard corner point automatic extraction device provided by the present invention comprises:

[0043] processor;

[0044] a memory storing executable instructions of the processor;

[0045] Wherein, the processor is configured to perform the steps of the automatic extraction method of checkerboard corner points by executing the executable instructions.

[0046] The computer-readable storage medium provided by the present invention is used to store a program, and when the program is executed, the steps of the automatic extraction method of chessboard corner points are implemented.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The present invention sets a marking pattern on a chessboard image, extracts the marking image, sequentially determines the position of each black grid area and the white grid area, and further realizes the extraction of the position of each chessboard corner point, avoids the problem that errors often occur in the identification of corner points when the chessboard image fills the entire camera's field of view, and realizes quick calibration of the camera. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings in the following descriptions are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without creative work. By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, purposes and advantages of the present invention will become more obvious:

[0050] Figure 1 A flowchart of the steps of the method for automatically extracting chessboard corner points in an embodiment of the present invention;

[0051] Figure 2 A flowchart of the steps of generating a checkerboard image in an embodiment of the present invention;

[0052] Figure 3 is a schematic diagram of a checkerboard image with a marking pattern in an embodiment of the present invention;

[0053] Figure 4 A flowchart of steps for identifying a marked image in an embodiment of the present invention;

[0054] Figure 5 A schematic diagram of a chessboard image in which the outline of a grid area is fitted in an embodiment of the present invention;

[0055] Figure 6 A flowchart of steps for identifying each black grid area and each white grid area in an embodiment of the present invention;

[0056] Figure 7 A schematic diagram of a checkerboard image in which each black grid area and each white grid area are identified in an embodiment of the present invention;

[0057] Figure 8 A flowchart of the steps of extracting each chessboard corner point in an embodiment of the present invention;

[0058] Fig. 9 A schematic diagram of a chessboard image for extracting each chessboard corner point in an embodiment of the present invention;

[0059] Fig.10 is a flowchart of the steps of the automatic extraction method of chessboard corner points in a modified example of the present invention;

[0060] Fig.11 Schematic diagram of modules of a system for automatically extracting chessboard corner points according to an embodiment of the present invention;

[0061] Fig.12 is a schematic diagram of the structure of a device for automatically extracting chessboard corner points in an embodiment of the present invention; and

[0062] Fig.13 Schematic diagram of the structure of a computer-readable storage medium in an embodiment of the present invention. DETAILED DESCRIPTION

[0063] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0064] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein, for example, can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0065] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0066] The invention provides a method for automatically extracting chessboard corner points, aiming to solve the problems existing in the prior art.

[0067] The following specific embodiments are used to describe in detail the technical solutions of the present invention and how the technical solutions of the present application solve the above-mentioned technical problems. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0068] Figure 1 FIG. 1 is a flowchart of the steps of the automatic extraction method of chessboard corner points in an embodiment of the present invention. Figure 1 As shown, the automatic extraction method of chessboard corner points provided by the present invention comprises the following steps

[0069] Step S1: Acquire a checkerboard image, wherein the checkerboard image includes at least one marking graphic, and the marking graphic is located in a square area of ​​the checkerboard image.

[0070] Figure 2 FIG. 1 is a flow chart of steps for generating a checkerboard image in an embodiment of the present invention. Figure 2 As shown, step S1 includes the following steps:

[0071] Step S101: obtaining a checkerboard image, and if the image is a multi-channel image, converting the checkerboard image into a first checkerboard grayscale image;

[0072] Step S102: downsampling or upsampling according to the resolution of the first chessboard grayscale image to generate a second chessboard grayscale image;

[0073] Step S103: binarizing the second checkerboard grayscale image to generate the checkerboard image.

[0074] In an embodiment of the present invention, the number of the marking graphics is multiple to ensure that there is a marking graphic in each field of view of the camera as the field of view of the camera moves. The marking graphics are set in the middle area of ​​the checkerboard and try not to be biased towards the side to ensure that the marking image is within the field of view of the camera. The resolution threshold can be set to 540×270. When the image resolution of the first checkerboard grayscale image is 1080×540, the number of downsampling is once. When binarizing the second checkerboard grayscale image, adaptive image binarization is used, and attention is paid to the selection of template size to try not to have oversaturation in the checkerboard.

[0075] In a variation of the present invention, the marking graphic includes any one or more of the following graphics:

[0076] - round shape;

[0077] - Ring-shaped;

[0078] -triangle;

[0079] -rectangle;

[0080] - Arbitrary polygons.

[0081] Figure 3 FIG. 1 is a schematic diagram of a checkerboard image with a marking pattern in an embodiment of the present invention. Figure 3 As shown, the marking pattern is a circle. The chessboard image includes black grid areas and white grid areas alternately arranged in sequence, like a chessboard.

[0082] Step S2: Identify the marked graphic area in the checkerboard image, and then extract the position information of the marked graphic in the checkerboard image.

[0083] Figure 4 FIG. 1 is a flow chart of steps for identifying a marked image in an embodiment of the present invention. Figure 4 As shown, step S2 includes the following steps:

[0084] Step S201: corroding each white grid area in the checkerboard image so that any adjacent white grid areas in the checkerboard image are separated from each other, thereby fitting a first contour of each white grid area;

[0085] Step S202: corroding each black grid area in the checkerboard image so that any adjacent black grid areas in the checkerboard image are separated from each other, thereby fitting a second contour of each black grid area;

[0086] Step S203: identifying the position of the marking graphic according to the topological relationship between the marking graphic and the first contour or the second contour.

[0087] In an embodiment of the present invention, the topological relationship is a containment relationship. The OpenCV function findContours() is used to find the contours of each grid area and the marked figure, and RotatedRect rect=fitEllipse(contours_w) is used to fit the contour of each grid area and calculate the center, radius and area occupied by each contour; the hierarchy contour number in the findContours function is used to identify the containment relationship between the first contour or the second contour according to the containment relationship between the contours to identify the marked figure.

[0088] In the embodiment of the present invention, when fitting the white grid area, the checkerboard image is color-flipped, and then the black grid area is fitted. And the white grid area and the black grid area that are misidentified are excluded according to the area threshold of each grid area. The area threshold of the grid area can be the average area of ​​all the grid areas.

[0089] Figure 5 FIG. 1 is a schematic diagram of a chessboard image in which the outline of the grid area is fitted in an embodiment of the present invention. Figure 5 As shown, each black grid area and white grid area is framed by an elliptical outline or a circular outline.

[0090] Step S3: Determine the position of each of the black grid area and the white grid area according to the position information of the marking graphic.

[0091] Figure 6 FIG. 1 is a flowchart of steps for identifying each black grid area and each white grid area in an embodiment of the present invention, as shown in FIG. Figure 6 As shown, step S3 includes the following steps:

[0092] Step S301: according to the position information of the marking graphic, four white grid areas and four black grid areas closest to the center of the marking graphic are found through the nearest neighbor relationship, and the four white grid areas and four black grid areas are used as a subgrid;

[0093] Step S302: Determine a grid area adjacent to the seed grid by expanding outwards from the seed grid through a cross ratio method, and then use the seed grid and the grid area adjacent to the seed grid as another sub-grid;

[0094] Step S303: Repeat step S302 to continuously expand the seed grid to determine the position of each of the black grid areas and the white grid areas.

[0095] In an embodiment of the present invention, each grid area is numbered. For example, if the grid area where the marking pattern is located is numbered (26, 26), then the multiple grid areas surrounding the grid area where the marking pattern is located are (25, 26), (25, 27), (26, 27), (27, 27), (27, 26), (27, 25), (26, 25), and (25, 26) clockwise from the left side.

[0096] The cross ratio method specifically determines the center point of the fourth grid area according to the extension line of the line connecting the center points of three grid areas arranged in sequence on the same straight line, and then determines the fourth grid area, so that each grid area can be determined by expanding the seed grid.

[0097] Figure 7 FIG. 1 is a schematic diagram of a checkerboard image for identifying each black grid area and each white grid area in an embodiment of the present invention. Figure 7 As shown, each black grid area and white grid area is identified and marked with dots, and then connected in sequence with lines.

[0098] Step S4: determining the position of each checkerboard corner point in the checkerboard image according to the position information of each black checkerboard area and the white checkerboard area.

[0099] Figure 8 FIG. 1 is a flowchart of the steps of extracting each chessboard corner point in an embodiment of the present invention. Figure 8 As shown, step S4 includes the following steps:

[0100] Step S401: determining the position of each checkerboard corner point of the checkerboard area where the mark pattern is located according to four white checkerboard areas and four black checkerboard areas closest to the center of the mark pattern;

[0101] Step S402: Whenever a sub-grid is generated, the position of each chessboard grid corner point inside the seed grid is determined according to each black grid area and the white grid area in the seed grid;

[0102] Step S403: As the seed grid expands, the position of each checkerboard corner point of the checkerboard image is determined in sequence.

[0103] In the embodiment of the present invention, the position of each chessboard corner point is determined according to the intersection of four adjacent grid areas in the horizontal direction and the vertical direction. In step S402, the inside of the seed grid is the position of the chessboard corner point excluding the outer frame of the seed grid.

[0104] The checkerboard corner points are numbered to mark the upper right corner of the figure as (0,0), the upper left corner as (-40,0), the lower left corner as (-40, -40), and the lower right corner as (0, -40). As the seed grid grows, the entire checkerboard image is spatially positioned and numbered for all checkerboard corner points.

[0105] In the embodiment of the present invention, the fourth checkerboard corner point may be determined by extending the line connecting three checkerboard corner points arranged in sequence and on the same straight line, thereby verifying the position of the checkerboard corner point determined above.

[0106] Fig. 9 FIG. 1 is a schematic diagram of extracting a checkerboard image of each checkerboard corner point in an embodiment of the present invention. Fig. 9 As shown, each chessboard corner point is marked by a dot and connected in sequence by lines.

[0107] In an embodiment of the present invention, a marking pattern is set on a checkerboard image, and the position of each of the black grid areas and the white grid areas is sequentially determined by extracting the marking image, thereby realizing the extraction of the position of each checkerboard corner point, thereby avoiding the problem of errors that often occur in the identification of corner points when the checkerboard image fills the entire camera's field of view, and realizing quick calibration of the camera.

[0108] Fig.10 FIG. 1 is a flowchart of the steps of the automatic extraction method of chessboard corner points in a modified example of the present invention. Fig.10 As shown, the automatic extraction method of chessboard corner points provided by the present invention further includes any one or more of the following steps:

[0109] Step S5: verifying the position area of ​​each chessboard corner point to determine whether the position area is the position area of ​​the chessboard corner point;

[0110] In the embodiment of the present invention, the first contour and / or the second contour are sampled, and the grayscale values ​​of the sampling points are spatially distributed to check whether the distribution satisfies the alternation of black edges or symmetry, that is, whether the condition of the checkerboard corner point is met.

[0111] Step S6: extracting sub-pixels of the position area of ​​each checkerboard corner point, and adjusting the position of each checkerboard corner point according to the sub-pixels of the position area of ​​each checkerboard corner point;

[0112] In the embodiment of the present invention, the subpixel of the position area of ​​each checkerboard corner point is extracted by using the OpenCV function subpixel refine, and then the position of each checkerboard corner point is adjusted.

[0113] Step S7: generating two-dimensional coordinates of the checkerboard corner points according to the positions of the checkerboard corner points, and generating three-dimensional coordinates of the checkerboard corner points according to the two-dimensional coordinates of the checkerboard corner points.

[0114] In an embodiment of the present invention, a two-dimensional coordinate system can be established on the plane where the chessboard is located to determine the two-dimensional coordinates of each corner point of the chessboard, and then the value of the Z axis is determined according to the distance between the plane where the chessboard is located and the camera to generate the three-dimensional coordinates of each corner point of the chessboard.

[0115] Fig.11 FIG. 1 is a schematic diagram of a module of a chessboard corner point automatic extraction system according to an embodiment of the present invention. Fig.11 As shown, the automatic extraction system of chessboard corner points provided by the present invention is used to implement the automatic extraction method of chessboard corner points, including:

[0116] An image acquisition module, used for acquiring a checkerboard image, wherein the checkerboard image includes at least one marking graphic, and the marking graphic is located in a square area of ​​the checkerboard image;

[0117] A marking pattern extraction module, used to identify the marking pattern area in the checkerboard image, and then extract the position information of the marking pattern in the checkerboard image;

[0118] A grid area recognition module, used to determine the position of each of the black grid area and the white grid area according to the position information of the marking pattern;

[0119] The corner point extraction module is used to determine the position of each checkerboard corner point in the checkerboard image according to the position information of each black checkerboard area and the white checkerboard area.

[0120] The present invention also provides a chessboard corner point automatic extraction device in an embodiment, comprising a processor and a memory, wherein executable instructions of the processor are stored, wherein the processor is configured to execute the steps of the chessboard corner point automatic extraction method by executing the executable instructions.

[0121] As described above, in this embodiment, the present invention sets a marking graphic on the checkerboard image, and by extracting the marking image, sequentially determines the position of each of the black grid areas and the white grid areas, thereby realizing the extraction of the position of each checkerboard corner point, thereby avoiding the problem of errors that often occur in the identification of corner points when the checkerboard image fills the entire camera's field of view, and realizing quick calibration of the camera.

[0122] It will be appreciated by those skilled in the art that various aspects of the present invention may be implemented as systems, methods or program products. Therefore, various aspects of the present invention may be specifically implemented in the following forms, namely: complete hardware implementation, complete software implementation (including firmware, microcode, etc.), or a combination of hardware and software implementations, which may be collectively referred to herein as "circuits", "modules" or "platforms".

[0123] Fig.12 This is a schematic diagram of the structure of the automatic extraction device for chessboard corner points of the present invention. Fig.12 The electronic device 600 according to this embodiment of the present invention is described. Fig.12 The electronic device 600 shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present invention.

[0124] like Fig.12 As shown, the electronic device 600 is in the form of a general computing device. The components of the electronic device 600 may include, but are not limited to: at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including the storage unit 620 and the processing unit 610), a display unit 640, etc.

[0125] The storage unit stores program codes, which can be executed by the processing unit 610, so that the processing unit 610 executes the steps of various exemplary embodiments of the present invention described in the above-mentioned chessboard corner point automatic extraction method section of this specification. For example, the processing unit 610 can execute the following steps: Figure 1 Follow the steps shown in .

[0126] The storage unit 620 may include a readable medium in the form of a volatile storage unit, such as a random access memory unit (RAM) 6201 and / or a cache memory unit 6202 , and may further include a read-only memory unit (ROM) 6203 .

[0127] The storage unit 620 may also include a program / utility 6204 having a set (at least one) of program modules 6205, such program modules 6205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0128] Bus 630 may represent one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0129] The electronic device 600 may also communicate with one or more external devices 700 (e.g., keyboards, pointing devices, Bluetooth devices, etc.), one or more devices that enable a user to interact with the electronic device 600, and / or any device that enables the electronic device 600 to communicate with one or more other computing devices (e.g., routers, modems, etc.). Such communication may be performed through an input / output (I / O) interface 650. Furthermore, the electronic device 600 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) through a network adapter 660. The network adapter 660 may communicate with other modules of the electronic device 600 through the bus 630. It should be understood that although Fig.12 Not shown, other hardware and / or software modules may be used in conjunction with electronic device 600, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms.

[0130] In an embodiment of the present invention, a computer-readable storage medium is further provided for storing a program, and the steps of the method for automatically extracting checkerboard corner points are implemented when the program is executed. In some possible implementations, various aspects of the present invention may also be implemented in the form of a program product, which includes a program code. When the program product is run on a terminal device, the program code is used to enable the terminal device to execute the steps of various exemplary implementations of the present invention described in the above-mentioned method for automatically extracting checkerboard corner points of this specification.

[0131] As shown above, when the program of the computer-readable storage medium of this embodiment is executed, the present invention sets a marking graphic on the checkerboard image, and sequentially determines the position of each of the black grid areas and the white grid areas by extracting the marking image, thereby realizing the extraction of the position of each checkerboard corner point, thereby avoiding the problem of errors that often occur in the identification of corner points when the checkerboard image fills the entire camera's field of view, and realizing quick calibration of the camera.

[0132] Fig.13 Schematic diagram of the structure of the computer-readable storage medium of the present invention. Fig.13 As shown, a program product 800 for implementing the above method according to an embodiment of the present invention is described, which can adopt a portable compact disk read-only memory (CD-ROM) and include program code, and can be run on a terminal device, such as a personal computer. However, the program product of the present invention is not limited thereto. In this document, a readable storage medium can be any tangible medium containing or storing a program, which can be used by or in combination with an instruction execution system, an apparatus or a device.

[0133] The program product may use any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of readable storage media (a non-exhaustive list) include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0134] Computer readable storage media may include data signals propagated in baseband or as part of a carrier wave, wherein readable program codes are carried. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The readable storage medium may also be any readable medium other than a readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, device, or device. The program codes contained on the readable storage medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination thereof.

[0135] Program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., through the Internet using an Internet service provider).

[0136] In an embodiment of the present invention, a marking pattern is set on a checkerboard image, and the position of each of the black grid areas and the white grid areas is sequentially determined by extracting the marking image, thereby realizing the extraction of the position of each checkerboard corner point, thereby avoiding the problem of errors that often occur in the identification of corner points when the checkerboard image fills the entire camera's field of view, and realizing quick calibration of the camera.

[0137] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will comply with the widest range consistent with the principles and novel features disclosed herein.

[0138] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for automatically extracting chessboard corner points, characterized in that: The following steps are included Step S1: Acquire a checkerboard image, wherein the checkerboard image includes at least one marking graphic, and the marking graphic is located in a square area of ​​the checkerboard image; Step S2: identifying the marked graphic area in the chessboard image, and then extracting the position information of the marked graphic in the chessboard image; Step S3: determining the position of each black grid area and white grid area in the chessboard image according to the position information of the marking pattern; Step S4: determining the position of each checkerboard corner point in the checkerboard image according to the position information of each black checkerboard area and the white checkerboard area; Wherein, the step S2 comprises the following steps: Step S201: corroding each white grid area in the checkerboard image so that any adjacent white grid areas in the checkerboard image are separated from each other, thereby obtaining a first outline of each white grid area; Step S202: corroding each black grid area in the checkerboard image so that any adjacent black grid areas in the checkerboard image are separated from each other, thereby obtaining a second contour of each black grid area; Step S203: identifying the position of the marking graphic according to the topological relationship between the marking graphic and the first contour or the second contour.

2. The method for automatically extracting chessboard corner points according to claim 1, characterized in that: The step S1 comprises the following steps: Step S101: obtaining a checkerboard image, and if the image is a multi-channel image, converting the checkerboard image into a first checkerboard grayscale image; Step S102: downsampling or upsampling according to the resolution of the first chessboard grayscale image to generate a second chessboard grayscale image; Step S103: binarizing the second checkerboard grayscale image to generate the checkerboard image.

3. The automatic extraction method of chessboard corner points according to claim 1, characterized in that: The step S3 comprises the following steps: Step S301: according to the position information of the marking graphic, four white grid areas and four black grid areas closest to the center of the marking graphic are found through the nearest neighbor relationship, and the four white grid areas and four black grid areas are used as a subgrid; Step S302: Determine a grid area adjacent to the seed grid by expanding outwards from the seed grid through a cross ratio method, and then use the seed grid and the grid area adjacent to the seed grid as another sub-grid; Step S303: Step S303: Repeat step S302 to continuously expand the seed grid to determine the position of each of the black grid areas and the white grid areas.

4. The automatic extraction method of chessboard corner points according to claim 3, characterized in that: The step S4 comprises the following steps: Step S401: determining the position of each checkerboard corner point of the checkerboard area where the mark pattern is located according to four white checkerboard areas and four black checkerboard areas closest to the center of the mark pattern; Step S402: Whenever a sub-grid is generated, the position of each chessboard grid corner point inside the seed grid is determined according to each black grid area and the white grid area in the seed grid; Step S403: As the seed grid expands, the position of each checkerboard corner point of the checkerboard image is determined in sequence.

5. The method for automatically extracting chessboard corner points according to claim 1, characterized in that: It also includes any one or more of the following steps: Step S5: verifying the position area of ​​each chessboard corner point to determine whether the position area is the position area of ​​the chessboard corner point; Step S6: extracting sub-pixels of the position area of ​​each checkerboard corner point, and adjusting the position of each checkerboard corner point according to the sub-pixels of the position area of ​​each checkerboard corner point; Step S7: generating two-dimensional coordinates of the checkerboard corner points according to the positions of the checkerboard corner points, and generating three-dimensional coordinates of the checkerboard corner points according to the two-dimensional coordinates of the checkerboard corner points.

6. The automatic extraction method of chessboard corner points according to claim 1, characterized in that: The marking graphics include any one or more of the following graphics: - round shape; - Ring-shaped; -triangle; -rectangle; - Arbitrary polygons.

7. A chessboard corner point automatic extraction system, used to implement the chessboard corner point automatic extraction method according to any one of claims 1 to 6, characterized in that: include: An image acquisition module, used for acquiring a checkerboard image, wherein the checkerboard image includes at least one marking graphic, and the marking graphic is located in a square area of ​​the checkerboard image; A marking pattern extraction module, used to identify the marking pattern area in the checkerboard image, and then extract the position information of the marking pattern in the checkerboard image; A grid area recognition module, used to determine the position of each of the black grid area and the white grid area according to the position information of the marking pattern; A corner point extraction module, used for determining the position of each checkerboard corner point in the checkerboard image according to the position information of each black checkerboard area and the white checkerboard area; The marking graphic extraction module comprises the following steps during processing: Step S201: corroding each white grid area in the checkerboard image so that any adjacent white grid areas in the checkerboard image are separated from each other, thereby obtaining a first outline of each white grid area; Step S202: corroding each black grid area in the checkerboard image so that any adjacent black grid areas in the checkerboard image are separated from each other, thereby obtaining a second contour of each black grid area; Step S203: identifying the position of the marking graphic according to the topological relationship between the marking graphic and the first contour or the second contour.

8. An automatic extraction device for chessboard corner points, characterized in that: include: processor; a memory storing executable instructions of the processor; Wherein, the processor is configured to perform the steps of the automatic checkerboard corner point extraction method described in any one of claims 1 to 6 by executing the executable instructions.

9. A computer-readable storage medium for storing a program, characterized in that: When the program is executed, the steps of the automatic extraction method of checkerboard corner points described in any one of claims 1 to 6 are implemented.

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