Rotatable camera calibration system and method

Abstract

The invention provides a rotatable camera calibration system and method, and the system comprises a target which is used for providing a feature map; the following assembly is used for driving the camera to reversely follow the rotation of the optical axis of the camera head of the camera; the control device is used for controlling the camera to rotate by a preset angle in a preset reverse direction, controlling the following assembly to drive the camera to rotate by the preset angle in a direction opposite to the preset direction, and controlling the camera to acquire a calibration image after the camera rotates along with the rotation, and calibrating the rotation of the camera based on the calibration image and the reference image. According to the rotatable camera calibration system and method, the camera is controlled to reversely follow the rotation of the optical axis of the camera in the calibration process, so that the visual field of the camera is always aligned with the feature pattern on the target, a large-size feature pattern is not needed, and a complex and expensive alignment mechanism is not needed due to the fact that the camera automatically follows the optical axis to rotate.

Description

Technical Field

[0001] The present application relates to the technical field of camera calibration, and in particular to a rotatable camera calibration system and method. Background Art

[0002] With the development of technology and the needs of various application scenarios, rotatable cameras or rotatable cameras have appeared on the market, which can rotate within a certain range to obtain a larger field of view. Compared with conventional cameras, the optical axis of rotatable cameras changes continuously and gradually within the rotation range, so that the field of view that the camera can cover is increased by N times. However, since the optical axis of the rotatable camera changes continuously and gradually within the rotation range, there will be multiple optical axis centers. Calibration of such cameras requires not only calibration of camera internal and external parameters, but also calibration of the camera's rotation accuracy. In the calibration process, a very large feature map (chart) is required, and the calibration and test equipment is complex and bulky, so the cost is high. Summary of the invention

[0003] In order to solve the above technical problems, the present application provides a rotatable camera calibration system and method. The system and method can control the camera to reversely follow the rotation of the optical axis of the camera during the calibration process, so that the field of view of the camera is always aligned with the feature map on the target, so there is no need for a large-sized feature map, and because the camera automatically rotates with the optical axis, there is no need for a complex and expensive alignment mechanism.

[0004] In a first aspect, the present application provides a rotatable camera calibration system, comprising:

[0005] A target, used to provide a feature map;

[0006] A following component, used to drive the camera to follow the rotation of the optical axis of the camera head in the opposite direction;

[0007] A control device is used to control the optical axis of the camera to rotate in a predetermined direction by a predetermined angle, and to control the following component to drive the camera to rotate in the opposite direction of the predetermined direction by a predetermined angle, and to control the camera to obtain a calibration image after the camera follows the rotation, and to calibrate the rotation angle of the camera based on the calibration image and the reference image.

[0008] According to the first aspect, the rotatable camera calibration system of the present application can control the camera to reversely follow the rotation of the optical axis of the camera through the following component during the calibration process, so that the field of view of the camera is always aligned with the feature map on the target, so there is no need for a large-size feature map, and because the camera automatically follows the rotation of the optical axis, there is no need for a complex and expensive alignment mechanism, thereby reducing costs and improving efficiency.

[0009] According to the first aspect, or any implementation of the first aspect above, calibrating the rotation angle of the camera based on the calibration image and the reference image includes: determining the actual rotation angle of the camera according to the calibration image and the reference image; and calibrating the rotation angle of the camera according to the actual rotation angle of the camera. This method is simple and efficient.

[0010] According to the first aspect, or any implementation of the first aspect above, determining the actual rotation angle of the camera according to the calibration image and the reference image includes:

[0011] Processing the calibration image so that the calibration image is consistent with the actual shape of the feature map;

[0012] Recognize the processed calibration image to determine the marking points in the calibration image;

[0013] Obtaining the center coordinates of the marking point in the calibration image;

[0014] The actual rotation angle of the camera head is determined according to the central coordinates of the marking point in the calibration image and the central coordinates of the corresponding marking point in the reference image.

[0015] This method is simple and efficient.

[0016] According to the first aspect, or any implementation of the first aspect above, the control device is further used to:

[0017] The camera is controlled to capture the reference image of the feature map, and the center coordinates of the marking point in the reference image are determined. In this way, the rotation angle of the camera can be calibrated by comparing with the reference image, which is simple and efficient.

[0018] According to the first aspect, or any implementation of the first aspect above, the following component includes:

[0019] A following mechanism, used to drive the camera to follow in reverse direction after the optical axis of the camera head rotates;

[0020] The clamping mechanism is used to fix the camera on the following mechanism and clamp the camera during the rotation process. This arrangement can be applied to a variety of products.

[0021] According to the first aspect, or any implementation of the first aspect above, the following mechanism includes:

[0022] A first rotating mechanism, used for driving the camera to rotate around a first direction;

[0023] A second rotating mechanism, used for driving the camera to rotate around a second direction, wherein the second direction is perpendicular to the first direction;

[0024] The angle measuring unit is used to measure the rotation angles of the first rotating mechanism and the second rotating mechanism, so that the following component drives the camera to rotate by the predetermined angle.

[0025] This setting enables the follow-up component to achieve accurate follow-up, making it easier to calibrate the rotation angle of the camera.

[0026] According to the first aspect, or any implementation of the first aspect above, the following mechanism further includes:

[0027] An adjustment unit is used to adjust the positions of the first rotating mechanism and the second rotating mechanism so that the center of the optical axis of the camera is aligned with the center of the marking point on the feature map.

[0028] This setting makes it easy to determine the basic relative position relationship between the camera and the feature map, thereby making it easy to obtain the coordinates of the marked points in the reference image and the calibration image.

[0029] In a second aspect, the present application provides a rotatable camera calibration method, the method applying the rotatable camera calibration system according to the first aspect, the method comprising:

[0030] Controlling the camera to capture a reference image of the feature map, and determining the center coordinates of the marking point in the reference image;

[0031] Control the optical axis of the camera to rotate in a predetermined direction and at a predetermined angle;

[0032] Controlling the follower component to drive the camera to rotate in the opposite direction of the predetermined direction by a predetermined angle;

[0033] Controlling the camera to capture the feature image to obtain a calibration image, and determining the actual rotation angle of the camera head according to the reference image and the calibration image;

[0034] The rotation angle of the camera is calibrated according to the actual rotation angle of the camera.

[0035] According to the second aspect, the rotatable camera calibration method of the present application can control the camera to reversely follow the rotation of the optical axis of the camera during the calibration process, so that the field of view of the camera is always aligned with the feature map on the target, so there is no need for a large-size feature map, and because the camera automatically follows the rotation of the optical axis, there is no need for a complex and expensive alignment mechanism, thereby reducing costs and improving efficiency.

[0036] According to the second aspect, or any implementation of the second aspect, determining the actual rotation angle of the camera according to the calibration image and the reference image includes:

[0037] Processing the calibration image so that the calibration image is consistent with the actual shape of the feature map;

[0038] Recognize the processed calibration image to determine the marking points in the calibration image;

[0039] Obtaining the center coordinates of the marking point in the calibration image;

[0040] The actual rotation angle of the camera head is determined according to the central coordinates of the marking point in the calibration image and the central coordinates of the corresponding marking point in the reference image.

[0041] According to the second aspect, or any implementation of the second aspect, calibrating the rotation angle of the camera according to the actual rotation angle of the camera includes:

[0042] Determine the difference between the actual rotation angle of the camera and the predetermined angle according to the actual rotation angle of the camera;

[0043] The camera is controlled to continue rotating according to the difference between the actual rotation angle of the camera and the predetermined angle, and the rotation of the camera is recalibrated based on the calibration image and the reference image until the rotation angle of the camera reaches the predetermined angle.

[0044] In a third aspect, the present application provides an electronic device, comprising: a memory and a processor, wherein the memory and the processor are coupled; the memory stores program instructions, and when the program instructions are executed by the processor, the electronic device executes the rotatable camera calibration method in the second aspect or any possible implementation of the second aspect.

[0045] In a fourth aspect, the present application provides a computer-readable medium for storing a computer program, wherein the computer program includes instructions for executing the method in the second aspect or any possible implementation of the second aspect.

[0046] In a fifth aspect, the present application provides a computer program comprising instructions for executing the method in the second aspect or any possible implementation of the second aspect.

[0047] In a sixth aspect, the present application provides a chip, the chip comprising a processing circuit and a transceiver pin, wherein the transceiver pin and the processing circuit communicate with each other through an internal connection path, and the processing circuit executes the method in the second aspect or any possible implementation of the second aspect to control the receiving pin to receive a signal and control the sending pin to send a signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A structural block diagram of a rotatable camera calibration system provided in an embodiment of the present application:

[0049] Figure 2 A schematic diagram of the structure of a rotatable camera calibration system provided in an embodiment of the present application;

[0050] Figure 3 A schematic diagram of the structure of a follower component provided in an embodiment of the present application;

[0051] Figure 4 A schematic diagram of the structure of a follow-up mechanism provided in an embodiment of the present application;

[0052] Figure 5 A schematic flow chart of a rotation-following calibration method for a rotatable camera provided in an embodiment of the present application;

[0053] Figure 6 An example of a feature diagram provided for an embodiment of the present application;

[0054] Figure 7 A schematic flowchart of a method for determining an actual rotation angle of a camera head provided in an embodiment of the present application;

[0055] Figure 8 A conversion comparison diagram of a reference image and a calibration image according to an embodiment of the present application;

[0056] Fig. 9 A schematic diagram of the marking point recognition principle of an embodiment of the present application;

[0057] Fig.10 A schematic block diagram of a device according to an embodiment of the present application. DETAILED DESCRIPTION

[0058] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0059] The term "and / or" in this article is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0060] The terms "first" and "second" in the description and claims of the embodiments of the present application are used to distinguish different objects rather than to describe a specific order of objects. For example, a first target object and a second target object are used to distinguish different target objects rather than to describe a specific order of target objects.

[0061] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0062] In the description of the embodiments of the present application, unless otherwise specified, the meaning of "multiple" refers to two or more than two. For example, multiple processing units refer to two or more processing units; multiple systems refer to two or more systems.

[0063] Camera (camcorder or camera) calibration is one of the most basic and important tasks in photogrammetry, computer vision and videography. Camera calibration refers to the determination of camera parameters, including intrinsic and extrinsic parameters, through experiments and calculations. For some high-precision measurement applications, the aberration coefficients need to be calibrated. The accuracy of the calibration results and the stability of the calibration algorithm directly affect the accuracy of subsequent work. The current active vision calibration method based on controllable rotation reduces the coupling between camera parameters by controlling the camera to rotate around the optical center (or near the optical center). It can separate the equivalent focal length from the camera parameters containing the aberration coefficients to achieve high-precision calibration. Then this method is combined with the traditional calibration method to achieve accurate calibration of other camera intrinsic and extrinsic parameters. Experiments show that this camera calibration technology based on controllable rotation and two-step method is not only simple and feasible to operate, but also can achieve high accuracy. In addition, if a simplified linear imaging model with equal equivalent focal lengths in horizontal and vertical directions and the image principal point as the image center is adopted, only one rotation movement is required to calibrate the camera linear parameters, and a satisfactory calibration effect can also be obtained.

[0064] For rotatable cameras or cameras, it is necessary not only to calibrate the internal and external parameters of the camera, but also to calibrate the rotation accuracy of the camera. The field of view that a rotatable camera or camera can cover increases by N times. Calibration of such cameras requires a very large feature map (chart), and the calibration and testing equipment is complex and bulky. For example, the collimator test solution used in the laboratory has a complex auxiliary alignment structure, large equipment size, low test efficiency, and high test cost.

[0065] Based on the above, the embodiment of the present application provides a rotatable camera calibration system and method, and a rotation follower device. The rotatable camera calibration system and method, and the rotation follower device can be applied to the calibration test of a rotatable camera or a camera with a large field of view, so that it no longer requires a complex alignment adjustment structure, improves the test efficiency, reduces the volume of the test equipment, and can reduce the size of the feature map required for the test. In the following, a rotatable camera will be used as an example to illustrate the structure and principle of the rotatable camera calibration system and method of the present application.

[0066] Figure 1 A structural block diagram of a rotatable camera calibration system provided in an embodiment of the present application.

[0067] like Figure 1 As shown, the rotatable camera calibration system provided in the embodiment of the present application includes 100 including a control device 101, a following component 102 and a target 103. The control device 101 is used to send instructions to the following component 102 and the camera 200, and receive the calibration image taken by the camera 200, determine the rotation angle of the camera 200 according to the calibration image, and then calibrate the rotation angle of the camera 200. The following component 102 is used to fix the camera 200, and when the camera 200 rotates the camera head, the camera 200 follows the camera head to rotate in the opposite phase, so that the field of view of the camera is always kept on the target 103. The target 103 is used to provide a feature map for the camera 200 to shoot. There are a number of marking points on the feature map, and the features of the marking points can adopt various suitable types as needed, which are not specifically limited here.

[0068] The control device 101 can be implemented as various electronic devices, such as a desktop computer, a portable computer, etc., which implements the calibration test of the rotatable camera by running a corresponding test program or application. The control device 101 is connected to the follower component 102 and the camera 200 in communication, and can send instructions to the follower component 102 and the camera 200, such as a rotation instruction, to indicate the rotation direction and rotation angle of the camera 200. The control device 101 can also receive a calibration image taken by the camera 200, so as to determine the actual rotation angle of the camera 200 according to the calibration image taken by the camera 200, so as to calibrate the rotation angle of the camera 200 according to the actual rotation angle of the camera 200.

[0069] The following component 102 is used to carry the camera 200 to be calibrated, and performs reverse following rotation when the camera 200 rotates the camera head, so that the field of view of the camera is always aimed at the target 103. For example, if the camera 200 rotates downward by 10 degrees according to the instruction of the control device 101, the following component 102 controls the camera 200 to rotate upward by 10 degrees according to the instruction, so that the field of view of the camera is still aimed at the target 103.

[0070] Figure 2 The structure of a rotatable camera calibration system provided in an embodiment of the present application is shown in FIG. Figure 2 The control device 101 is not shown in FIG. Figure 2 The direction perpendicular to the target 103 is the Y-axis direction, the vertical direction is the Z-axis direction, and the direction perpendicular to the YZ-axis plane is the X-axis direction.

[0071] like Figure 2 As shown, the following component 102 includes a first rotating mechanism 1021 and a second rotating mechanism 1022. The first rotating mechanism 1021 is used to rotate the camera 200 around a first direction. The second rotating mechanism 1022 is used to rotate the camera 200 around a second direction. The first direction is perpendicular to the second direction. Taking the target 103 as the front as an example, the first rotating mechanism 1021 drives the camera 200 to rotate up and down, and the second rotating mechanism 1022 can drive the camera 200 to rotate left and right. The camera 200 is mounted on the first rotating mechanism 1021, and the first rotating mechanism 1021 is mounted on the second rotating mechanism 1022. The specific implementation forms of the first rotating mechanism 1021 and the second rotating mechanism 1022 can adopt different structures as needed, as long as the rotation in the set direction is satisfied.

[0072] like Figure 2 As shown, the target 103 has a characteristic map, and the characteristic map has preset marking points. The following component 102 and the target 103 are installed on the same working platform and have a determined relative position relationship, so the relative position relationship between the camera 200 and the target or the characteristic map can be predetermined, so as to facilitate the subsequent calibration of the rotation angle of the camera 200.

[0073] In the embodiment of the present application, when the camera 200 is installed on the following component 102 , the rotation axis center of the first rotating mechanism 1021 and the rotation axis center of the second rotating mechanism 1022 are aligned with the camera head center (ie, optical center) of the camera 200 .

[0074] Figure 3 A schematic diagram of the structure of a follower component provided in an embodiment of the present application.

[0075] like Figure 3As shown, in one embodiment of the present application, the following component 102 includes a following mechanism 1023 and a clamping mechanism 1024. The following mechanism 1023 includes a servo motor, a hollow rotating platform and a fixed mounting structure, which is used to reversely follow the rotational movement of the optical axis of the camera 200. The hollow rotating platform is used to achieve the following rotation. For example, the aforementioned hollow rotating platform may include a first rotating mechanism and a second rotating mechanism, which are used to achieve rotation in two directions (for example, up and down rotation and left and right rotation). The fixed mounting structure is used to install and fix the hollow rotating platform. The servo motor is used to drive the hollow rotating platform to rotate a desired angle. The following mechanism 1023 can adopt various suitable structures to achieve the above functions.

[0076] The clamping mechanism 1024 includes a flip cylinder, a clamping and pressing claw, and a fixing pin, which are used to clamp the camera 200 when the following mechanism 1023 makes the camera 200 rotate along the optical axis. The flip cylinder is connected to the clamping and pressing claw to control the clamping and releasing of the clamping and pressing claw. The fixing pin is used to fix the flip cylinder and the clamping claw. The clamping mechanism 1024 can adopt various suitable shapes and structures according to the above principles, which are not specifically limited here.

[0077] The clamping mechanism 1024 is installed on the following mechanism 1023. Exemplarily, the clamping structure and the following mechanism 1023 are detachably connected.

[0078] Figure 4 A schematic diagram of the structure of a following mechanism provided in an embodiment of the present application.

[0079] like Figure 4 As shown, the following mechanism of the embodiment of the present application includes a 90-degree rotation position sensor 1, a 90-degree sensor mounting sheet metal 2, a turntable sensor plate 3, a hollow rotating platform fixed vertical plate 4 and 17, a transmission connecting member 5, a 0-degree sensor mounting sheet metal 6, a 0-degree rotation position sensor 7, an X-axis hollow rotating platform 8, a first fixed reinforcement 9, a second fixed reinforcement 10, a Z-axis hollow rotating platform 11, a Z-axis rotation servo motor 12, a rotation following component alignment adjustment plate 13, a following mechanism mounting base 14, a fixture mounting base 15, an X-axis first rotation limiter 16, a fixing member 18, a rotating connecting member 19, an X-axis second rotation limiter 20, a gyroscope 21, a third fixed reinforcement 22, a fourth fixed reinforcement 23, a support plate 24, an angle adjuster 25, a Z-axis first rotation limiter 26, and a Z-axis second rotation limiter 27.

[0080] The rotation follower assembly centering adjustment plate 13 is mounted on the follower mechanism mounting base plate 14, and the Z-axis hollow rotating platform 11, the Z-axis rotating servo motor 12, the Z-axis first rotating stopper 26 and the Z-axis second rotating stopper 27 are mounted on the rotation follower assembly centering adjustment plate 13. The rotation follower assembly centering adjustment plate 13 is used to adjust the relative position of the center (camera optical axis center) of the product to be calibrated (e.g., camera 200) mounted on the follower assembly 102 and the center of the feature map on the target 103, so that the two are aligned, thereby facilitating the acquisition of the basic relative position relationship between the product to be calibrated and the feature map. The Z-axis hollow rotating platform 11 is used to rotate around the Z-axis direction, and it may include a rotating shaft and its related connecting parts. The Z-axis rotating servo motor 12 is connected to the Z-axis hollow rotating platform 11, and is used to drive the Z-axis hollow rotating platform 11 to rotate around the Z-axis direction. The Z-axis first rotating stopper 26 is used to limit the Z-axis hollow rotating platform 11 when it rotates counterclockwise. The second Z-axis rotation limiter 27 is used to limit the Z-axis hollow rotating platform 11 when it rotates clockwise.

[0081] The support plate 24 is connected and fixed to the Z-axis hollow rotating platform 11 , and when the Z-axis hollow rotating platform 11 rotates around the Z-axis direction, the support plate 24 can be driven to rotate around the Z-axis direction.

[0082] The first fixing reinforcement 9, the second fixing reinforcement 10, the third fixing reinforcement 22, and the fourth fixing reinforcement 23 are installed on the support plate 24 for fixing the hollow rotating platform fixed vertical plates 4 and 17. Specifically, the first fixing reinforcement 9 is installed on one side of the support plate 24, and the hollow rotating platform fixed vertical plate 4 is fixed on the first fixing reinforcement 9. A pair of second fixing reinforcements 10 are installed and fixed on the support plate 24, and are respectively fixedly connected to the two ends of the hollow rotating platform fixed vertical plate 4, thereby strengthening the connection and fixation of the first fixing reinforcement 9 and the support plate 24. The fourth fixing reinforcement 23 is installed and fixed on the other side of the support plate 24, and the hollow rotating platform fixed vertical plate 17 is installed and fixed on the fourth fixing reinforcement 23. A pair of third fixing reinforcements 22 are installed and fixed on the support plate 24, and are respectively fixedly connected to the two ends of the hollow rotating platform fixed vertical plate 17, thereby strengthening the connection and fixation of the fourth fixing reinforcement 23 and the support plate 24.

[0083] The X-axis hollow rotating platform 8 is installed and fixed on the outer side of the hollow rotating platform fixed vertical plate 4 (the side away from the hollow rotating platform fixed vertical plate 17), and includes a reducer and an X-axis rotating servo motor connected to the reducer. The transmission connecting member 5 is installed on the inner side of the hollow rotating platform fixed vertical plate 4 (the side facing the hollow rotating platform fixed vertical plate 17), and is connected to the X-axis hollow rotating platform 8. The transmission connecting member 5 is rotatably connected to the hollow rotating platform fixed vertical plate 4, and it can rotate relative to the hollow rotating platform fixed vertical plate 4 under the drive of the X-axis hollow rotating platform 8 (reducer and servo motor). The transmission connecting member 5 is roughly semicircular, and a roughly circular hole is formed thereon, which is used to form a rotational connection with the hollow rotating platform fixed vertical plate 4. The rotating connecting member 19 is installed on the inner side of the hollow rotating platform fixed vertical plate 17 (the side facing the hollow rotating platform fixed vertical plate 4), and the rotating connecting member 19 is roughly cylindrical. The fixing member 18 is sleeved on the rotating connecting member 19 and forms a rotating connection with the rotating connecting member 19, that is, the fixing member 18 can rotate relative to the rotating connecting member 19. The line connecting the rotation center of the rotating connecting member 19 and the rotation center of the transmission connecting member 5 is parallel to the X-axis, forming the rotation axis of the X-axis.

[0084] In the embodiment of the present application, the axis centerline of the X-axis rotation shaft intersects with the axis centerline of the Z-axis hollow rotation platform 11 , which becomes the rotation center of the follower mechanism in this article.

[0085] The fixture mounting base 15 is fixedly connected to the transmission connector 5 and the fixing member 18. Driven by the X-axis hollow rotating platform 8, the fixture mounting base 15 can rotate around the axis of the X-axis, thereby driving the clamping mechanism 1024 mounted thereon to rotate around the axis of the X-axis, and further driving the product to be calibrated (such as the camera 200) to rotate around the axis of the X-axis.

[0086] A 90-degree sensor mounting sheet metal 2 and a 0-degree sensor mounting sheet metal are also mounted on the hollow rotating platform fixed vertical plate 4. The 90-degree sensor mounting sheet metal 2 is mounted on the top of the hollow rotating platform fixed vertical plate 4, and the 90-degree rotation in place sensor 1 is mounted on the 90-degree sensor mounting sheet metal 2. The 0-degree sensor mounting sheet metal 6 is mounted on the front end of the hollow rotating platform fixed vertical plate 4, and the 0-degree rotation in place sensor 7 is mounted on the 0-degree sensor mounting sheet metal 6. The line passing through the 90-degree rotation in place sensor 1 and parallel to the Z axis and the line passing through the 0-degree rotation in place sensor 7 and parallel to the Y axis are perpendicular to each other.

[0087] A turntable sensor sheet 3 is also installed on the transmission connection member 5. The turntable sensor sheet 3 can rotate with the transmission connection member 5, and the position of the turntable sensor sheet 3 can be obtained by shielding the sensor by the turntable sensor sheet 3, so as to determine the rotation angle of the transmission connection member 5.

[0088] The first X-axis rotation limiter 16 and the second X-axis rotation limiter 20 are installed on the inner side of the hollow rotating platform fixed vertical plate 17, which are used to limit the rotation of the fixture mounting base 15 around the X-axis. Among them, the first X-axis rotation limiter 16 is located at the top of the hollow rotating platform fixed vertical plate 17, and the second X-axis rotation limiter 20 is located at the front end of the hollow rotating platform fixed vertical plate 17. The line passing through the first X-axis rotation limiter 16 and parallel to the Z axis and the line passing through the second X-axis rotation limiter 20 and parallel to the Y axis are perpendicular to each other. The line connecting the first X-axis rotation limiter 16 and the 90-degree rotation position sensor 1 is parallel to the X-axis. The line connecting the second X-axis rotation limiter 20 and the 0-degree rotation position sensor 7 is parallel to the X-axis.

[0089] A gyroscope 21 is installed on the fixture mounting base 15, which can be used to detect the rotation angle of the fixture mounting base 15, and cooperate with the turntable sensor sheet 3 to determine the rotation angle of the fixture mounting base 15 to provide accuracy.

[0090] An angle adjuster 25 is installed on the fixture mounting base 15, which is used to adjust the angle of the product to be calibrated (such as camera 200) relative to the fixture mounting base 15 to match the posture of the product to be calibrated (such as camera 200) during the test, because different test items have different posture requirements / camera center posture requirements.

[0091] The following mechanism provided in the embodiment of the present application can more accurately control the rotation of the product to be calibrated, thereby accurately achieving reverse following of the rotation of the camera optical axis.

[0092] Figure 5 A schematic flowchart of a rotation and following calibration method for a rotatable camera provided in an embodiment of the present application.

[0093] like Figure 5 As shown, the rotation following calibration method of a rotatable camera provided in an embodiment of the present application includes:

[0094] S501, instructing the camera to capture a reference image of the feature map, and determining the center coordinates of the marking point in the reference image;

[0095] S502, instructing the camera head to rotate in a predetermined direction and by a predetermined angle;

[0096] S503, instructing the follower component to drive the camera to rotate in the opposite direction of the predetermined direction by a predetermined angle;

[0097] S504, instructing the camera to capture the feature map to obtain a calibration image, and determining the actual rotation angle of the camera according to the calibration image;

[0098] S505: Calibrate the rotation angle of the camera according to the actual rotation angle of the camera.

[0099] Examples of pre-made feature maps are Figure 6 As shown, there are several marking points on it. Figure 6 For example, there are 5 marking points. Before step S501, refer to Figure 2 , by adjusting e.g. Figure 3 and Figure 4 The following component shown aligns the optical axis center (i.e., optical center) of the camera 200 with the center of the marked point of the feature map, thereby obtaining the initial relative position relationship between the camera 200 and the feature map. The center of the marked point of the feature map refers to the average center position of multiple marked points, which can generally be designed as the center of the feature map. Initially, the camera optical axis is perpendicular to the feature map. When the optical axis center (i.e., optical center) of the camera 200 is aligned with the center of the marked point of the feature map, since the distance between the camera and the feature map is determined, the basic relative position relationship between the camera and the feature map can be determined, and the basic relative position relationship can transform the marked point on the feature map into a point on the camera image.

[0100] In step S501, the control device sends a command to the camera, instructing the camera to capture a reference image of the feature map and determine the center coordinates of the marking point on the reference image.

[0101] The determination of the center coordinates of the marking points on the reference image may include the following steps: first, determining the correspondence between the marking points on the reference image and the marking points on the feature map based on the basic relative position relationship, and then determining the center of each marking point through an algorithm, thereby determining the center coordinates of each marking point.

[0102] In step S502, the control device sends a command to the camera, instructing the camera head to rotate in a predetermined direction and at a predetermined angle. That is, the camera is instructed to rotate the optical axis in a predetermined direction and at a predetermined angle, for example, to rotate downward 10 degrees relative to the camera around the X axis (in degrees). Figure 2 The positions shown are for reference, i.e. the camera optical axis is rotated 10 degrees clockwise around the X-axis).

[0103] In step S503, the control device sends a command to the follower component, instructing the follower component to drive the camera to rotate in the opposite direction of the predetermined direction by a predetermined angle. That is, the rotation direction of the camera is opposite to the rotation direction of the optical axis, and the rotation angle is the same, which is referred to as reverse following in this article. For example, in step S502, the optical axis rotates downward 10 degrees around the X-axis, then in step S503, the follower component drives the camera to rotate upward 10 degrees around the X-axis (by Figure 2 The position shown is for reference, that is, the follower assembly drives the camera to rotate 10 degrees counterclockwise around the X axis). In this way, since the camera rotates in the reverse direction, the optical axis of the camera still faces the characteristic map on the target in front. Even if the camera rotates continuously or significantly within the rotation angle range, due to the reverse following of the follower assembly, the optical axis of the camera always faces the characteristic map, so that the camera's field of view always remains in the front (with Figure 2This allows the entire calibration test process to be completed without the need for a large-sized feature map.

[0104] Since the rotation angle of the following component is accurate, that is, the actual rotation angle is the same as the indicated rotation angle, if the actual rotation angle of the camera optical axis is the same as the indicated rotation angle, then after the following component reverses, the center of the camera's optical axis is still aligned with the center of the marker point on the feature map, and the coordinates of the marker point are the same as those on the reference image. On the contrary, if the optical axis rotation is inaccurate, then after the following component reverses, the center of the camera's optical axis is no longer aligned with the center of the marker point on the feature map, and the coordinates of the marker point are different from those on the reference image. Therefore, the actual rotation angle of the optical axis can be determined based on the coordinates of the marker point on the feature map taken after rotational following, and calibration is performed based on the actual rotation angle of the optical axis.

[0105] It should be understood that steps S502 and S503 may be performed successively or simultaneously.

[0106] In step S504, after the following component completes the following rotation, the control device instructs the camera to shoot the feature map to obtain a calibration image, and determines the actual rotation angle of the camera according to the calibration image. That is, after the following component completes the following rotation, the camera shoots the feature map to obtain an image of the feature map after the following rotation, which is called a calibration image. The calibration image is then sent to the control device, and the control device determines the actual rotation angle of the camera optical axis according to the calibration image.

[0107] How to determine the actual rotation angle of the camera optical axis will be described in detail later.

[0108] In S505, the rotation angle of the camera is calibrated according to the actual rotation angle of the camera. Specifically, the rotation angle of the camera is calibrated according to the difference between the actual rotation angle of the camera (that is, the actual rotation angle of the camera optical axis) and the predetermined angle indicated by the control device. For example, if the camera is instructed to rotate downward by 10 degrees, and then the actual rotation angle of the camera is determined to be 8 degrees, the camera is instructed to continue to rotate downward by 2 degrees, and then it is determined based on the calibration image after the camera is rotated whether the actual rotation angle of the camera is 2 degrees. If not, continue to execute steps S502, S504, S505 or steps S502, S503, S504, S505 until the final rotation angle of the camera reaches the initial predetermined angle.

[0109] As for whether the following component follows during the subsequent camera calibration rotation during this process, it is determined according to actual needs. For example, if the subsequent rotation of the camera may cause the camera field of view to exceed the range of the feature map, the following component will continue to follow. If it does not exceed the range of the feature map, the following component may not follow.

[0110] Figure 7 A schematic flowchart of a method for determining the actual rotation angle of a camera head provided in an embodiment of the present application.

[0111] like Figure 7 As shown, the method for determining the actual rotation angle of the camera head provided in the embodiment of the present application includes:

[0112] Step S701, processing the calibration image to make the calibration image consistent with the actual shape of the feature map.

[0113] Since the optical axis is no longer perpendicular to the feature map after the camera is rotated, the calibration image taken after the rotation is deformed, such as Figure 8 As shown, A is the reference image of the feature map, and B is the calibration image of the feature map.

[0114] In order to obtain the actual rotation angle of the camera optical axis, the calibration image needs to be processed first to restore it to an image consistent with the actual shape of the feature map. In S701, the calibration image is restored to an image consistent with the actual shape of the feature map by a corresponding restoration algorithm. Figure 8 As shown, image B is restored to image C.

[0115] Step S702: Recognize the processed calibration image and determine the marking points in the calibration image.

[0116] For example, the marker points may be segmented by using a local dynamic segmentation method, and the sizes of the marker points in the processed calibration image may be matched with the marker points in the reference image to identify the marker points. Fig. 9 shown.

[0117] It should be understood that various suitable marking point recognition methods can be used as needed, and this application does not make any specific limitation on this.

[0118] Step S703, obtaining the center coordinates of the marking points in the calibration image.

[0119] Exemplarily, image segmentation, detection and recognition technology may be used to locate the center position of each of the marking points, and then the center coordinates of each of the marking points may be obtained.

[0120] Step S704, determining the actual rotation angle of the camera head according to the center coordinates of the marking point in the calibration image and the coordinates of the corresponding marking point in the reference image.

[0121] The conversion relationship between the center coordinates of the marking point in the calibration image and the coordinates of the corresponding marking point in the reference image is related to the actual rotation angle of the camera optical axis. The relative tilt angle between the image plane and the plane where the feature map is located or the target can be determined based on the center coordinates of the marking point in the calibration image and the coordinates of the corresponding marking point in the reference image. This angle is related to the difference between the actual rotation angle of the camera optical axis and the predetermined angle. Therefore, the relative tilt angle between the image plane and the plane where the feature map is located or the target after the rotation is determined, and the actual rotation angle of the camera can be determined. As for the specific algorithm processing process, various known or subsequently developed algorithms can be used for processing, and no specific limitation is made here.

[0122] It should be understood that the actual rotation angle of the camera can be determined based on the center coordinates of a marking point on the calibration image and the center coordinates on the reference image, and the actual rotation angle of the camera can be determined based on the center coordinates of multiple marking points on the calibration image and the center coordinates on the reference image.

[0123] In one example, Fig.10 A schematic block diagram of a device 300 according to an embodiment of the present application is shown. The device 300 may include: a processor 301 and a transceiver / transceiver pin 302 , and optionally, a memory 303 .

[0124] The components of the device 300 are coupled together via a bus 304, wherein the bus 304 includes a power bus, a control bus, and a status signal bus in addition to a data bus. However, for the sake of clarity, all buses are referred to as bus 304 in the figure.

[0125] Optionally, the memory 303 may be used for instructions in the aforementioned method embodiment. The processor 301 may be used to execute instructions in the memory 303, and control the receiving pin to receive a signal, and control the sending pin to send a signal.

[0126] The apparatus 300 may be the electronic device or a chip of the electronic device in the above method embodiment.

[0127] Among them, all relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module, and will not be repeated here.

[0128] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A rotatable camera calibration system, It is characterized in that include: A target, used to provide a feature map; A following component, used to drive the camera to follow the rotation of the camera head in the reverse direction; A control device is used to control the optical axis of the camera to rotate in a predetermined direction by a predetermined angle, and to control the following component to drive the camera to rotate in the opposite direction of the predetermined direction by a predetermined angle, and to control the camera to obtain a calibration image after the camera follows the rotation, and to calibrate the rotation angle of the camera based on the calibration image and the reference image.

2. The rotatable camera calibration system according to claim 1, It is characterized in that The step of calibrating the rotation angle of the camera based on the calibration image and the reference image includes: Determine an actual rotation angle of the camera head according to the calibration image and the reference image; The rotation angle of the camera is calibrated according to the actual rotation angle of the camera.

3. The rotatable camera calibration system according to claim 2, It is characterized in that Determining the actual rotation angle of the camera head according to the calibration image and the reference image comprises: Processing the calibration image so that the calibration image is consistent with the actual shape of the feature map; Recognize the processed calibration image to determine the marking points in the calibration image; Obtaining the center coordinates of the marking point in the calibration image; The actual rotation angle of the camera head is determined according to the central coordinates of the marking point in the calibration image and the central coordinates of the corresponding marking point in the reference image.

4. The rotatable camera calibration system according to claim 1, It is characterized in that The control device is also used for: The camera is controlled to capture a reference image of the feature map, and the center coordinates of the marking point in the reference image are determined.

5. The rotatable camera calibration system according to any one of claims 1 to 4, It is characterized in that The following component comprises: A following mechanism, used to drive the camera to follow in reverse direction after the optical axis of the camera head rotates; The clamping mechanism is used to fix the camera on the following mechanism and clamp the camera during the rotation process.

6. The rotatable camera calibration system according to claim 5, It is characterized in that The following mechanism comprises: A first rotating mechanism, used for driving the camera to rotate around a first direction; A second rotating mechanism, used for driving the camera to rotate around a second direction, wherein the second direction is perpendicular to the first direction; The angle measuring unit is used to measure the rotation angles of the first rotating mechanism and the second rotating mechanism, so that the following component drives the camera to rotate by the predetermined angle.

7. The rotatable camera calibration system according to claim 6, It is characterized in that The following mechanism also includes: An adjustment unit is used to adjust the positions of the first rotating mechanism and the second rotating mechanism so that the center of the optical axis of the camera is aligned with the center of the marking point on the feature map.

8. A rotatable camera calibration method, the method being applied to the rotatable camera calibration system according to any one of claims 1 to 7, It is characterized in that The method comprises: Controlling the camera to capture a reference image of the feature map, and determining the center coordinates of the marking point in the reference image; Control the optical axis of the camera to rotate in a predetermined direction and at a predetermined angle; Controlling the follower component to drive the camera to rotate in the opposite direction of the predetermined direction by a predetermined angle; Controlling a camera to capture the feature map to obtain a calibration image, and determining an actual rotation angle of the camera head according to the reference image and the calibration image; The rotation angle of the camera is calibrated according to the actual rotation angle of the camera.

9. The rotatable camera calibration method according to claim 8, It is characterized in that The step of determining the actual rotation angle of the camera head according to the calibration image and the reference image comprises: Processing the calibration image so that the calibration image is consistent with the actual shape of the feature map; Recognize the processed calibration image to determine the marking points in the calibration image; Obtaining the center coordinates of the marking point in the calibration image; The actual rotation angle of the camera head is determined according to the central coordinates of the marking point in the calibration image and the central coordinates of the corresponding marking point in the reference image.

10. The rotatable camera calibration method according to claim 8, It is characterized in that The step of calibrating the rotation angle of the camera according to the actual rotation angle of the camera includes: Determine the difference between the actual rotation angle of the camera and the predetermined angle according to the actual rotation angle of the camera; The camera is controlled to continue rotating according to the difference between the actual rotation angle of the camera and the predetermined angle, and the rotation of the camera is recalibrated based on the rotated calibration image and the reference image until the rotation angle of the camera reaches the predetermined angle.

11. An electronic device, It is characterized in that include: a memory and a processor, the memory and the processor being coupled; The memory stores program instructions, and when the program instructions are executed by the processor, the electronic device executes the rotatable camera calibration method as described in any one of claims 8 to 10.

12. A computer-readable storage medium, It is characterized in that It comprises a computer program, characterized in that when the computer program is run on an electronic device, the electronic device executes the rotatable camera calibration method as described in any one of claims 8 to 10.

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