A calibration method, apparatus, device, and storage medium for a tetranocular imaging system

Abstract

This application discloses a calibration method, apparatus, device, and storage medium for a quad-lens imaging system, belonging to the field of image processing technology. The quad-lens imaging system includes a first camera, a second camera, a third camera, and a fourth camera; the second and third cameras constitute a first visual group, and the first and fourth cameras constitute a second visual group. The method includes: identifying the distance between a calibration board and the quad-lens imaging system; if the distance is within a first range, then using the first visual group to capture an image of the calibration board, and calibrating the first visual group based on the marker points on the calibration board in the image; if the distance switches to a second range, then using the second visual group to capture an image of the calibration board, and calibrating the second visual group based on the marker points on the calibration board in the image. This technical solution can achieve accurate positioning of marker points at different distances over a wider range by calibrating the quad-lens imaging system, thereby expanding the applicability of the quad-lens imaging system.

Description

Technical Field

[0001] This application belongs to the field of image processing technology, and specifically relates to a calibration method, apparatus, device and storage medium for a four-eye imaging system. Background Technology

[0002] Today, binocular vision technology is developing rapidly and is gradually playing a role in various industries, bringing a certain degree of impact to people's daily work and life. Especially for some fields that require precise positioning, such as the medical field, the need for precise positioning is becoming increasingly urgent.

[0003] In existing technologies, a binocular vision positioning system is typically used, in which two cameras are fixed to the same rigid body at a certain distance and angle. During operation, the two cameras respectively acquire mapped images of the same feature point within their field of view. Then, based on the placement of the two cameras and the positions of the feature point obtained in the images, the specific position of the feature point in three-dimensional space is calculated using the principle of triangulation.

[0004] However, when using a binocular positioning system for optical positioning, there is a problem of difficulty in accurately locating the marked point in a large field of view or in long-distance observation. Summary of the Invention

[0005] This application provides a calibration method, apparatus, device, and storage medium for a quad-lens imaging system. The purpose of the invention is to enable accurate positioning of marker points at different distances over a wider range by calibrating the quad-lens imaging system, thereby expanding the applicability of the quad-lens imaging system.

[0006] In a first aspect, embodiments of this application provide a calibration method for a quad-eye imaging system, the method comprising:

[0007] Identify the distance between the calibration plate and the quad-eye imaging system;

[0008] If the distance is within a first range, the first vision group takes an image of the calibration board, and the first vision group is calibrated according to the marking points of the calibration board in the image.

[0009] If the distance is switched to the second range, the second vision group is used to capture an image of the calibration board, and the second vision group is calibrated according to the marking points of the calibration board in the image;

[0010] Furthermore, before identifying the distance between the calibration plate and the quad-lens imaging system, the method further includes:

[0011] The first range and the second range are determined jointly based on the lens focal lengths of the first vision group and the second vision group.

[0012] Furthermore, before identifying the distance between the calibration plate and the quad-lens imaging system, the method further includes:

[0013] The effective field of view of the first visual group is determined based on the field of view angles of the second camera and the third camera;

[0014] as well as,

[0015] The effective field of view of the second visual group is determined based on the field of view angles of the first camera and the fourth camera.

[0016] Furthermore, based on the field of view angles of the second camera and the third camera, the effective field of view of the first visual group is determined, including:

[0017] Construct a discrete set of spatial points along the shooting direction of the first visual group;

[0018] If a discrete point in the discrete spatial point set has a projection point in both the second and third cameras of the first visual group, it is retained; if a discrete point in the discrete spatial point set does not have a projection point in either the second or third camera of the first visual group, it is deleted.

[0019] Based on the retention results, the effective field of view of the first visual group is determined;

[0020] as well as,

[0021] The effective field of view of the second visual group is determined based on the field of view angles of the first camera and the fourth camera, including:

[0022] Construct a discrete set of spatial points along the shooting direction of the second visual group;

[0023] If a discrete point in the discrete spatial point set has a projection point in both the first and fourth cameras of the second visual group, it is retained; if a discrete point in the discrete spatial point set does not have a projection point in either the first or fourth camera of the second visual group, it is deleted.

[0024] Based on the retention results, the effective field of view of the second visual group is determined.

[0025] Furthermore, the first visual group is calibrated based on the marker points on the calibration board in the image, including:

[0026] Obtain the distance between the calibration board and the first vision group;

[0027] Extract the sub-pixel coordinates of the marker points on the calibration board in the image;

[0028] Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, the second camera and the third camera of the first vision group are calibrated.

[0029] Furthermore, the second visual group is calibrated based on the marker points on the calibration board in the image, including:

[0030] Obtain the distance between the calibration board and the second vision group;

[0031] Extract the sub-pixel coordinates of the marker points on the calibration board in the image;

[0032] Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, the first camera and the fourth camera of the second vision group are calibrated.

[0033] Secondly, embodiments of this application provide a calibration device for a quad-eye imaging system, the device comprising:

[0034] Distance recognition module: used to identify the distance between the calibration board and the four-nozzle imaging system;

[0035] First calibration module: used to capture images of the calibration board using a first vision group, and to calibrate the first vision group based on the marked points of the calibration board in the images;

[0036] The second calibration module is used to capture images of the calibration board using the second vision group and to calibrate the second vision group based on the marker points on the calibration board in the images.

[0037] Furthermore, the device also includes:

[0038] Range determination module: used to jointly determine a first range and a second range based on the lens focal length of the first visual group and the lens focal length of the second visual group.

[0039] Thirdly, embodiments of this application provide a control device, which includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the steps of the method described in the first aspect.

[0040] Fourthly, embodiments of this application provide a readable storage medium on which a program or instructions are stored, which, when executed by a processor, implement the steps of the method described in the first aspect.

[0041] Fifthly, embodiments of this application provide a chip, the chip including a processor and a communication interface, the communication interface being coupled to the processor, the processor being used to run programs or instructions to implement the method as described in the first aspect.

[0042] In this embodiment, the distance between the calibration board and the four-lens imaging system is identified. If the distance is within a first range, a first vision group is used to capture an image of the calibration board, and the first vision group is calibrated based on the marker points on the calibration board in the image. If the distance switches to a second range, a second vision group is used to capture an image of the calibration board, and the second vision group is calibrated based on the marker points on the calibration board in the image. This technical solution can achieve equally accurate positioning of marker points at different distances over a wider range. Attached Figure Description

[0043] Figure 1 This is a schematic flowchart of the calibration method for the four-eye imaging system provided in Embodiment 1 of this application;

[0044] Figure 2 This is a flowchart illustrating another calibration method for a four-eye imaging system provided in Embodiment 2 of this application;

[0045] Figure 3 This is a flowchart illustrating another calibration method for a four-eye imaging system provided in Embodiment 3 of this application;

[0046] Figure 4 This is a flowchart illustrating the method for determining the effective field of view of the first visual group provided in Embodiment 3 of this application;

[0047] Figure 5 This is a flowchart illustrating the method for determining the effective field of view of the second visual group provided in Embodiment 3 of this application;

[0048] Figure 6 This is a flowchart illustrating the method for calibrating the first visual group provided in Embodiment 4 of this application;

[0049] Figure 7 This is a flowchart illustrating the method for calibrating the second vision group provided in Embodiment 4 of this application;

[0050] Figure 8 This is a schematic diagram of the calibration device for the four-eye imaging system provided in Embodiment 5 of this application;

[0051] Figure 9 This is a schematic diagram of the control device provided in Embodiment Six of this application. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining this application and not for limiting it. It should also be noted that, for ease of description, only the parts relevant to this application are shown in the drawings, not all of them. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0053] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0054] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0055] The calibration method, apparatus, device, and storage medium of the quad-lens imaging system provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0056] Example 1

[0057] Figure 1 This is a schematic flowchart of the calibration method for a quad-eye imaging system provided in Embodiment 1 of this application. Figure 1 As shown, the specific steps include the following:

[0058] S101. Identify the distance between the calibration plate and the quad-eye imaging system.

[0059] This solution is used in scenarios where a four-camera imaging system (first, second, third, and fourth cameras) is used for calibration. All cameras are sequentially mounted on the main axis, and a first vision group and a second vision group are configured. Switching between the first and second vision groups will be involved during calibration and actual use.

[0060] In this scheme, during the calibration and actual use of the quad-lens imaging system, the first and second visual groups of the quad-lens imaging system can be switched via a control terminal, as well as the movement of the calibration board can be controlled. The description will take the control terminal as the executing entity.

[0061] A calibration plate can be a flat plate with a fixed-spacing pattern array. It can be used to correct lens distortion and 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, thus improving the accuracy of image measurement in machine vision applications. In this scheme, the calibration plate is positioned on the normal line. It can be moved within a certain range by installing a driving device, or its position can be moved manually. The calibration plate has calibration holes, and the switching between the first and second vision groups can be performed by calculating the number of pixels passing through these holes.

[0062] A quad-camera imaging system is an imaging system composed of four cameras used to achieve precise positioning over a large area. It can include a first camera, a second camera, a third camera, and a fourth camera. The four cameras are located on the same baseline, with the first, second, third, and fourth cameras each tilted at a certain angle from their upper ends towards the center. The second and third cameras are set at a certain distance from each other, and the distance between the first and second cameras is equal to the distance between the third and fourth cameras. The distance between the second and third cameras is greater than the distance between the first and second cameras. For example, the distance between the second and third cameras is 490mm, and the distance between the first and second cameras is 80mm. The first and fourth cameras are symmetrical about the normal, and the second and third cameras are symmetrical about the camera axis.

[0063] This solution utilizes a ranging device, such as a laser rangefinder, to measure the position of the marker points. This laser rangefinder is connected to the control terminal via a data cable and mounted on the main axis, aligned with the camera baseline, which helps reduce distance measurement errors. A coordinate system is used to accurately represent the coordinates of each camera calibration point. Specifically, the coordinate values ​​of the marker points for the second and third cameras are first determined based on the measurement results. This establishes a coordinate system, designated as the first coordinate system, and the coordinates of the marker points in this first coordinate system can be denoted as... Next, determine the coordinate values ​​of the first and fourth camera points respectively, and construct another coordinate system, which is called the second coordinate system. The coordinates of the marker point in the second coordinate system can be denoted as... The transformation relationship between the first and second coordinate systems can be represented by the rotation matrix R and the translation matrix T, and can be calculated using the following formula:

[0064]

[0065] In the formula, the rotation matrix R and the translation matrix T represent the rotation and translation matrices from the camera 2 coordinate system to the camera 1 coordinate system. Generally, at least three points are needed to calculate the values ​​of R and T. By representing the first and second coordinate systems in the same coordinate system, the coordinate system of the four-lens imaging system is obtained. The Z-coordinate in the camera system coordinate system represents the distance between the four-lens imaging system and the calibration board. Furthermore, by identifying this Z-coordinate through the four-lens imaging system, the distance between the four-lens imaging system and the calibration board can be determined.

[0066] S102. If the distance is within a first range, the first vision group takes an image of the calibration board and calibrates the first vision group according to the marking points of the calibration board in the image.

[0067] The first vision group consists of a second camera and a third camera. The first range can be used to represent the distance between the calibration board and the baseline, and can be determined based on the distance between the four-eye imaging system and the calibration board. In this scheme, the first range can be represented as a small distance range, such as 800mm to 1500mm. The marker points on the calibration board can be used to identify the positions of the images captured by the cameras.

[0068] In this scheme, if the distance between the quad-vision imaging system and the calibration board is within a first range, the second and third cameras are activated and simultaneously capture images of the calibration board. The first vision group is calibrated based on the marked points on the calibration board in the images captured by the first vision group.

[0069] S103. If the distance is switched to the second range, the second vision group is used to capture an image of the calibration board, and the second vision group is calibrated according to the marking points of the calibration board in the image.

[0070] The second vision group consists of the first camera and the fourth camera. The second range can also be used to represent the distance between the calibration board and the baseline, and can be determined based on the distance between the four-eye imaging system and the calibration board. In this scheme, combined with the above example, the second range can be represented as a distance range larger than the first range, for example, 1500mm to 2500mm.

[0071] If the distance between the quad-vision imaging system and the calibration board is within the second range, then the first and fourth cameras are activated and simultaneously capture images of the calibration board. The second vision group is calibrated based on the marked points on the calibration board in the images captured by the second vision group.

[0072] In this real-time example, if the distance between the calibration board and the quad-lens imaging system is within a first range, the first vision group is used to capture images of the calibration board. If the distance between the calibration board and the quad-lens imaging system exceeds the first range but falls within a second range, the system can switch to the second vision group to capture images of the calibration board automatically, manually by pressing a switch, or via a touchscreen button. Alternatively, a recognition device can be installed to automatically identify the boundary between the first and second ranges and send the identified data to the control terminal, enabling automatic switching between the first and second vision groups. In another possible embodiment, the number of pixels passing through the calibration aperture in the image will vary depending on the distance between the calibration board and the quad-lens imaging system, and can be set according to actual conditions. For example, when the number of pixels passing through the calibration aperture in the image is greater than or equal to 10, the first vision group is used to capture images of the calibration board. When the number of pixels passing through the calibration aperture in the image is less than 10, the image clarity will be relatively reduced, and the system switches to the second vision group to capture images of the calibration board. The switching of vision groups can also be done manually or automatically. Specifically, when the recognition device detects that the number of pixels has changed to a certain value, it automatically switches between the first visual group and the second visual group.

[0073] In this embodiment, the conversion relationship between the first visual group and the second visual group can be calibrated at the boundary between the first range and the second range corresponding to the first visual group and the second visual group, respectively, so as to obtain the spatial transformation relationship between the two visual groups.

[0074] In this embodiment, the distance between the calibration board and the four-nozzle imaging system is identified. If the distance is within a first range, an image of the calibration board is captured using a first vision group, and the first vision group is calibrated based on the marker points on the calibration board in the image. If the distance switches to a second range, an image of the calibration board is captured using a second vision group, and the second vision group is calibrated based on the marker points on the calibration board in the image. This solution selects either the first or second vision group based on the distance between the calibration board and the four-nozzle imaging system, thereby achieving equally accurate positioning of marker points at different distances over a wider range.

[0075] Example 2

[0076] Figure 2 This is a flowchart illustrating another calibration method for a quad-eye imaging system provided in Embodiment 2 of this application. Figure 2 As shown, the specific steps include the following:

[0077] S201. Determine the first range and the second range together based on the lens focal length of the first visual group and the lens focal length of the second visual group.

[0078] The focal length of the lenses in the first vision group can include the focal lengths of the second and third cameras, where the second and third cameras have the same focal length. The focal length of the lenses in the first vision group can be a close focal length, providing a wide angle of view. In this scheme, the focal length of the lenses in the first vision group can be used to photograph the calibration board within a relatively small area. The focal length of the lenses in the second vision group can include the focal lengths of the first and fourth cameras, where the first and fourth cameras have the same focal length. The focal length of the lenses in the second vision group can be a telephoto focal length, providing a relatively narrower angle of view. The focal length of the lenses in the second vision group is greater than that of the lenses in the first vision group.

[0079] In this embodiment, the first range and the second range are determined jointly based on the focal lengths of the lenses of the first visual group and the second visual group. Specifically, if the focal length of the lens of the first visual group is 8mm and the focal length of the lens of the second visual group is 16mm, the first range and the second range can be determined based on the maximum and minimum distances at which the 8mm lens can capture images and the maximum distance at which the 16mm lens can capture images. If the minimum distance at which the 8mm lens can capture images is 800mm and the maximum distance is 1500mm, and the maximum distance at which the 16mm lens can capture images is 2500mm, then the first range can be determined to be 800mm to 1500mm, and the second range to be 1500mm to 2500mm.

[0080] S202. Identify the distance between the calibration plate and the quad-eye imaging system.

[0081] S203. If the distance is within a first range, the first vision group takes an image of the calibration board and calibrates the first vision group according to the marking points of the calibration board in the image.

[0082] S204. If the distance is switched to the second range, the second vision group is used to capture an image of the calibration board, and the second vision group is calibrated according to the marking points of the calibration board in the image.

[0083] In this embodiment, the first range and the second range are determined by jointly determining the focal length of the lens of the first visual group and the focal length of the lens of the second visual group. The switching between the first visual group and the second visual group is then performed based on the first range and the second range, which is beneficial to achieve the same level of accurate positioning of marker points at different distances over a larger range.

[0084] Example 3

[0085] Figure 3 This is a flowchart illustrating another calibration method for a quad-eye imaging system provided in Embodiment 3 of this application. Figure 3 As shown, the specific steps include the following:

[0086] S301. Determine the effective field of view of the first visual group based on the field of view angles of the second camera and the third camera; and determine the effective field of view of the second visual group based on the field of view angles of the first camera and the fourth camera.

[0087] The field of view (FOP) represents the range of fields of view that a camera can capture. The size of the FOP determines the range of fields of view captured by the camera. Generally, the longer the focal length of the camera, the smaller the FOP and the farther the field of view. The effective field of view of the first visual group represents the area that can be captured within the first visual group, i.e., the area that the second and third cameras can capture. The effective field of view of the second visual group represents the area that can be captured by the second visual group, i.e., the area that the first and fourth cameras can capture.

[0088] In this scheme, since the first visual group consists of the second and third cameras, and the second visual group consists of the first and fourth cameras, the field of view angles of the first, second, third, and fourth cameras will be acquired separately. The area where the field of view angles of the second and third cameras overlap is defined as the effective field of view. Similarly, the area where the field of view angles of the first and fourth cameras overlap is defined as the effective field of view.

[0089] S302. Identify the distance between the calibration plate and the quad-eye imaging system.

[0090] S303. If the distance is within a first range, the first vision group takes an image of the calibration board and calibrates the first vision group according to the marking points of the calibration board in the image.

[0091] S304. If the distance is switched to the second range, the second vision group is used to capture an image of the calibration board, and the second vision group is calibrated according to the marking points of the calibration board in the image.

[0092] In this embodiment, by determining the effective field of view of the first visual group based on the field of view angles of the second and third cameras, and by determining the effective field of view of the second visual group based on the field of view angles of the first and fourth cameras, it is beneficial to ensure that the calibration board image can be completely captured by the first and second visual groups, and further achieve accurate positioning.

[0093] Figure 4 This is a flowchart illustrating the method for determining the effective field of view of the first visual group provided in Embodiment 3 of this application. Figure 4 As shown, the specific steps include the following:

[0094] S401. Construct a set of discrete spatial points in the shooting direction of the first visual group.

[0095] The shooting direction of the first visual group can be the same as that of the second and third cameras. The discrete spatial point set can be distributed in a cuboid shape in front of the camera, and the number of spatial points can be determined according to the pinhole imaging principle and the number of pixels of each camera. The number of spatial points will vary depending on the distance between the calibration plate and the camera, which affects the number of pixels passing through the calibration hole.

[0096] For example, in this scheme, the camera in the first vision group has a pixel size of 8mm, and the Z-coordinate of the marker point is between 800mm and 1500mm. Therefore, the calibration board can be moved to a position Z = 800mm away from the line connecting the two camera principal points, defining a first spatial discrete point surface. Since the Z-coordinate value remains unchanged, all spatial discrete points are at the same distance from the line connecting the two camera principal points, thus forming a spatial discrete point surface. This first spatial discrete point surface can be a spatial discrete point surface formed by all spatial discrete points at Z = 800mm. Subsequently, a spatial discrete point surface can be set every 10mm. The last spatial discrete point surface of the first vision group is located at a distance Z = 1500mm from the line connecting the two camera principal points. The width and height of each surface are W = 1500mm and H = 1500mm, respectively, avoiding the judgment and processing of unnecessary discrete points. Therefore, a set of discrete spatial points can be constructed as the distance between the four-eye imaging system and the calibration board changes.

[0097] S402. If the discrete points in the discrete spatial point set have projection points in both the second and third cameras of the first visual group, then retain them; if the discrete points in the discrete spatial point set do not have projection points in either the second or third camera of the first visual group, then delete them.

[0098] A projection point represents a projected pixel in the camera. In this scheme, this projection point is used to determine whether discrete points should be retained. Based on the pinhole imaging principle, the correspondence between spatial points and pixels determines the projection point of each discrete point in the camera. Specifically, based on the pinhole imaging principle, the correspondence between spatial points and pixels is as follows:

[0099]

[0100] Where (u,v) are pixel coordinates, f x =f / d x f y =f / d y It is the focal length of the camera in the x, y direction of the image pixel coordinates, P(X w Y w Z w Let p be the coordinates of a point in space. The coordinates of a point p in space are calculated using equation (2). i The projected pixels on the left and right cameras, if a point has a projection point p on both the left and right cameras. iIf pi is true, then point pi is retained; otherwise, point p is not. i If a point is not within the field of view of the binocular system, it is removed. The resulting spatial point pi is within the field of view of the binocular system. Therefore, the space occupied by the remaining spatial point is the field of view of the binocular system.

[0101] S403. Based on the retention results, determine the effective field of view of the first visual group;

[0102] The retained result can be the combination of discrete points retained after deleting projection points that do not exist in the second and third cameras in the above steps. This result is the result of excluding invalid fields of view in the first visual group, and can be determined as the valid field of view of the first visual group.

[0103] In this embodiment, a discrete spatial point set is constructed along the shooting direction of the first visual group; it is determined whether each discrete point in the discrete spatial point set has a projection point in both the second and third cameras of the first visual group, and the non-existent discrete points are deleted; based on the retention results, the effective field of view of the first visual group is determined. Eliminating marker points that cannot be captured within the first visual group helps to eliminate invalid positioning fields of view, narrow the positioning range, and improve the positioning accuracy of the calibration points.

[0104] Figure 5 This is a flowchart illustrating the method for determining the effective field of view of the second visual group provided in Embodiment 3 of this application. Figure 5 As shown, the specific steps include the following:

[0105] S501. Construct a set of discrete spatial points in the shooting direction of the second visual group.

[0106] The shooting direction of the second vision group can be the same as the orientation of the first and fourth cameras.

[0107] For example, in this scheme, the camera pixels in the second vision group are 16mm, and the Z-coordinates of the marker points are 1500mm to 2500mm. Therefore, the calibration plate can be moved to a position Z = 1500mm from the line connecting the two camera principal points, defining the first spatial discrete point surface of the second vision group. Subsequently, a spatial discrete point surface can be set every 10mm. The last spatial discrete point surface of the second vision group is located at a position Z = 2500mm from the line connecting the two camera principal points. The width and height of each surface are W = 1500mm and H = 1500mm, respectively, avoiding unnecessary judgment and processing of discrete points.

[0108] S502. If the discrete points in the discrete spatial point set have projection points in both the first and fourth cameras of the second visual group, then retain them; if the discrete points in the discrete spatial point set do not have projection points in either the first or fourth camera of the second visual group, then delete them.

[0109] For details on the implementation of this step, please refer to S402. It will not be repeated here.

[0110] S503. Based on the retention results, determine the effective field of view of the second visual group.

[0111] The retained result can be the combination of discrete points retained after deleting projection points that do not exist in the first and fourth cameras in the above steps. This result is the result of excluding invalid fields of view in the second visual group, and can be determined as the valid field of view of the second visual group.

[0112] In this embodiment, a discrete spatial point set is constructed along the shooting direction of the second visual group; it is determined whether each discrete point in the discrete spatial point set has a projection point in both the first and fourth cameras of the second visual group, and the non-existent discrete points are deleted; based on the retention results, the effective field of view of the second visual group is determined. Eliminating marker points that cannot be captured within the second visual group helps to eliminate invalid positioning fields of view, narrow the positioning range, and improve the positioning accuracy of the calibration points.

[0113] Example 4

[0114] Figure 6 This is a flowchart illustrating the method for calibrating the first visual group provided in Embodiment 4 of this application. Figure 6 As shown, the specific steps include the following:

[0115] S601. Obtain the distance between the calibration board and the first vision group.

[0116] The control terminal sends a data request command to the ranging device. After receiving the data request command, the ranging device sends the distance information between the calibration board and the first vision group to the control terminal, and the control terminal receives the distance information.

[0117] S602. Extract the sub-pixel coordinates of the marker points on the calibration plate in the image.

[0118] Subpixel coordinates represent the position of a pixel in an image. These subpixel coordinates are non-integer values ​​and are more precise than traditional pixel coordinates, further improving the positioning accuracy of calibration points. These subpixel coordinates can be generated from data measured by a laser rangefinder and displayed on the screen of the terminal device. The control terminal can wirelessly connect to the terminal device. The terminal device sends images captured by the second and third cameras to the control terminal, which receives the images and extracts the subpixel coordinates of the marker points on the calibration board within the images.

[0119] S603. Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, calibrate the second camera and the third camera of the first vision group.

[0120] This scheme uses the relative distance and sub-pixel coordinates of the marked points on the calibration board obtained through the above steps, as well as the pinhole imaging principle, to calibrate the second and third cameras respectively, and establish a first coordinate system based on the calibration points of the second and third cameras.

[0121] In this embodiment, the distance between the calibration board and the first vision group and the sub-pixel coordinates of the marker points of the calibration board in the image are obtained respectively. Then, based on the distance and the sub-pixel coordinates of the marker points, the second camera and the third camera of the first vision group are calibrated according to the imaging principle, which helps to improve the calibration accuracy of the cameras in the first vision group.

[0122] Figure 7 This is a flowchart illustrating the method for calibrating the second visual group provided in Embodiment 4 of this application. Figure 7 As shown, the specific steps include the following:

[0123] S701. Obtain the distance between the calibration board and the second vision group.

[0124] The control terminal sends a data request command to the ranging device. After receiving the data request command, the ranging device sends the distance information between the calibration board and the second vision group to the control terminal, and the control terminal receives the distance information.

[0125] S702. Extract the sub-pixel coordinates of the marker points on the calibration plate in the image.

[0126] The control terminal can be wirelessly connected to the terminal device. The terminal device sends the images captured by the first and fourth cameras to the control terminal. The control terminal receives the images and extracts the sub-pixel coordinates of the marker points on the calibration board in the images.

[0127] S703. Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, calibrate the first camera and the fourth camera of the second vision group.

[0128] This scheme uses the relative distance and sub-pixel coordinates of the marked points on the calibration board obtained through the above steps, as well as the pinhole imaging principle, to calibrate the first camera and the fourth camera respectively, and establish a second coordinate system based on the calibration points of the first camera and the fourth camera.

[0129] In this embodiment, the distance between the calibration board and the second vision group and the sub-pixel coordinates of the marker points on the calibration board in the image are obtained respectively. Then, based on the distance and the sub-pixel coordinates of the marker points, the first camera and the fourth camera of the second vision group are calibrated according to the imaging principle, which helps to improve the calibration accuracy of the cameras in the second vision group, thereby achieving accurate positioning of the long-distance calibration point.

[0130] Example 5

[0131] Figure 8 This is a schematic diagram of the calibration device for the quad-eye imaging system provided in Embodiment 5 of this application. Figure 8 As shown, the device includes:

[0132] Distance recognition module 81 is used to identify the distance between the calibration board and the four-eye imaging system;

[0133] The first calibration module 82 is used to capture an image of the calibration board using a first vision group, and to calibrate the first vision group based on the marking points of the calibration board in the image.

[0134] The second calibration module 83 is used to capture images of the calibration board using the second vision group, and to calibrate the second vision group based on the marking points of the calibration board in the images.

[0135] Furthermore, the device also includes:

[0136] Range determination module: used to jointly determine a first range and a second range based on the lens focal length of the first visual group and the lens focal length of the second visual group.

[0137] Furthermore, the device also includes:

[0138] Effective field of view determination module: used to determine the effective field of view of the first visual group based on the field of view angles of the second camera and the third camera;

[0139] Used to determine the effective field of view of the second visual group based on the field of view angles of the first camera and the fourth camera.

[0140] Furthermore, the effective field of view determination module is specifically used for:

[0141] Construct a discrete set of spatial points along the shooting direction of the first visual group;

[0142] If a discrete point in the discrete spatial point set has a projection point in both the second and third cameras of the first visual group, it is retained; if a discrete point in the discrete spatial point set does not have a projection point in either the second or third camera of the first visual group, it is deleted.

[0143] Based on the retention results, the effective field of view of the first visual group is determined;

[0144] The effective field of view determination module is also specifically used for:

[0145] Construct a discrete set of spatial points along the shooting direction of the second visual group;

[0146] If a discrete point in the discrete spatial point set has a projection point in both the first and fourth cameras of the second visual group, it is retained; if a discrete point in the discrete spatial point set does not have a projection point in either the first or fourth camera of the second visual group, it is deleted.

[0147] Based on the retention results, the effective field of view of the second visual group is determined.

[0148] Furthermore, the first calibration module 82 is specifically used for:

[0149] Obtain the distance between the calibration board and the first vision group;

[0150] Extract the sub-pixel coordinates of the marker points on the calibration board in the image;

[0151] Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, the second camera and the third camera of the first vision group are calibrated.

[0152] Furthermore, the second calibration module 83 is specifically used for:

[0153] Obtain the distance between the calibration board and the second vision group;

[0154] Extract the sub-pixel coordinates of the marker points on the calibration board in the image;

[0155] Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, the first camera and the fourth camera of the second vision group are calibrated.

[0156] In this embodiment, the distance between the calibration board and the four-nozzle imaging system is identified. If the distance is within a first range, an image of the calibration board is captured using a first vision group, and the first vision group is calibrated based on the marker points on the calibration board in the image. If the distance switches to a second range, an image of the calibration board is captured using a second vision group, and the second vision group is calibrated based on the marker points on the calibration board in the image. This solution selects either the first or second vision group based on the distance between the calibration board and the four-nozzle imaging system, thereby achieving equally accurate positioning of marker points at different distances over a wider range.

[0157] Example 6

[0158] This application also provides an electronic device that can integrate the calibration device of the tetranocular imaging system provided in this application. Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. (Reference) Figure 9The computer device includes: an input device 93, an output device 94, a memory 92, and one or more processors 91; the memory 92 is used to store one or more programs; when one or more programs are executed by one or more processors 91, the one or more processors 91 implement the calibration method of the four-lens imaging system as described in the above embodiment. The input device 93, output device 94, memory 92, and processor 91 can be connected via a bus or other means. Figure 9 Taking the example of a connection between China and Israel via a bus.

[0159] Example 7

[0160] This application also provides a readable storage medium storing a program or instructions. When the program or instructions are executed by a processor, they implement the various processes of the above-described calibration method embodiment for the four-eye imaging system and achieve the same technical effect. To avoid repetition, they will not be described again here.

[0161] The processor is the processor in the control device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0162] Example 8

[0163] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the above-described calibration method embodiment for the four-eye imaging system, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0164] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0165] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0166] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0167] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0168] The above description is merely a preferred embodiment and the technical principles employed in this application. This application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions that can be made by those skilled in the art will not depart from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of this application, the scope of which is determined by the scope of the claims.

Claims

1. A calibration method for a tetranocular imaging system, characterized in that, The quad-camera imaging system includes a first camera, a second camera, a third camera, and a fourth camera. The distance between the first camera and the second camera is equal to the distance between the third camera and the fourth camera. The distance between the second camera and the third camera is greater than the distance between the first camera and the second camera. The second camera and the third camera form a first visual group, and the first camera and the fourth camera form a second visual group. The focal length of the lens in the second visual group is greater than the focal length of the lens in the first visual group. The method includes: The first range and the second range are determined jointly based on the lens focal length of the first vision group and the lens focal length of the second vision group. Identify the distance between the calibration plate and the quad-eye imaging system; If the distance is within the first range, the first vision group is used to capture an image of the calibration board, and the first vision group is calibrated according to the marking points of the calibration board in the image. If the distance switches to the second range, the second vision group is used to capture an image of the calibration board, and the second vision group is calibrated according to the marking points of the calibration board in the image.

2. The method according to claim 1, characterized in that, Before identifying the distance between the calibration plate and the quad-lens imaging system, the method further includes: The effective field of view of the first visual group is determined based on the field of view angles of the second camera and the third camera; as well as, The effective field of view of the second visual group is determined based on the field of view angles of the first camera and the fourth camera.

3. The method according to claim 2, characterized in that, The effective field of view of the first visual group is determined based on the field of view angles of the second camera and the third camera, including: Construct a discrete set of spatial points along the shooting direction of the first visual group; If a discrete point in the discrete spatial point set has a projection point in both the second and third cameras of the first visual group, it is retained; if a discrete point in the discrete spatial point set does not have a projection point in either the second or third camera of the first visual group, it is deleted. Based on the retention results, the effective field of view of the first visual group is determined; as well as, The effective field of view of the second visual group is determined based on the field of view angles of the first camera and the fourth camera, including: Construct a discrete set of spatial points along the shooting direction of the second visual group; If a discrete point in the discrete spatial point set has a projection point in both the first and fourth cameras of the second visual group, it is retained; if a discrete point in the discrete spatial point set does not have a projection point in either the first or fourth camera of the second visual group, it is deleted. Based on the retention results, the effective field of view of the second visual group is determined.

4. The method according to claim 1, characterized in that, The first visual group is calibrated based on the marker points on the calibration board in the image, including: Obtain the distance between the calibration board and the first vision group; Extract the sub-pixel coordinates of the marker points on the calibration board in the image; Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, the second camera and the third camera of the first vision group are calibrated.

5. The method according to claim 1, characterized in that, The second visual group is calibrated based on the marker points on the calibration board in the image, including: Obtain the distance between the calibration board and the second vision group; Extract the sub-pixel coordinates of the marker points on the calibration board in the image; Based on the distance and the sub-pixel coordinates of the marker point, and based on the imaging principle, the first camera and the fourth camera of the second vision group are calibrated.

6. A calibration device for a tetranocular imaging system, characterized in that, The quad-camera imaging system includes a first camera, a second camera, a third camera, and a fourth camera. The distance between the first camera and the second camera is equal to the distance between the third camera and the fourth camera. The distance between the second camera and the third camera is greater than the distance between the first camera and the second camera. The second camera and the third camera form a first visual group, and the first camera and the fourth camera form a second visual group. The focal length of the lens in the second visual group is greater than the focal length of the lens in the first visual group. The device includes: Range determination module: used to jointly determine a first range and a second range based on the lens focal length of the first visual group and the lens focal length of the second visual group; Distance recognition module: used to identify the distance between the calibration board and the four-nozzle imaging system; First calibration module: used to capture images of the calibration board using the first vision group, and to calibrate the first vision group based on the marking points of the calibration board in the images; The second calibration module is used to capture images of the calibration board using the second vision group and to calibrate the second vision group based on the marker points of the calibration board in the images.

7. A control device, characterized in that, It includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor, wherein the program or instructions, when executed by the processor, implement the steps of the calibration method for a quad-eye imaging system as described in any one of claims 1-5.

8. A readable storage medium, characterized in that, The readable storage medium stores a program or instructions that, when executed by a processor, implement the steps of the calibration method for the quad-eye imaging system as described in any one of claims 1-5.

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