CN216772458U - Rotating mechanism and system for camera calibration - Google Patents

Abstract

The application discloses a rotary mechanism and system for camera is markd, rotary mechanism includes: a load-bearing platform; a first rotating mechanism having a first rotating shaft; the second rotating mechanism is provided with a second rotating shaft, the second rotating mechanism is arranged on the bearing platform, and the first rotating mechanism is fixed on the second rotating mechanism; the camera fixing frame is fixed on the first rotating mechanism and used for mounting a camera, the center lines of the rotating shafts of the first rotating shaft and the second rotating shaft are vertically intersected, the intersection point is overlapped with the optical center of the camera, the optical axis of the camera is coaxial with the first rotating shaft, so that the target can be obtained by the camera through the target after the camera is shot and amplified through the range extender, a virtual target image is formed through the rotation of the rotating mechanism, the target does not need to be moved when the camera is calibrated, the image only needs to be collected in the rotating process of the rotating mechanism, the camera calibration difficulty is reduced, and meanwhile, the camera is calibrated in a smaller calibration space quickly and accurately.

Description

Rotating mechanism and system for camera calibration

Technical Field

The present application relates to the field of camera calibration technologies, and in particular, to a rotating mechanism and a system for camera calibration.

Background

The camera calibration is one of key technologies in the work of machine vision, photogrammetry, 3D imaging, image geometric correction and the like, and the main function of the camera calibration is to estimate internal and external parameters of the camera. The accuracy of the calibration result and the stability of the calibration algorithm directly affect the accuracy of subsequent work. In a general calibration method, because a plurality of images in different postures need to be acquired, a calibration plate or a camera needs to be manually moved, and the distance between a target and the camera during calibration also needs to meet the working distance of the camera, so that a large target and a large calibration space are caused.

SUMMERY OF THE UTILITY MODEL

The application provides a rotary mechanism and camera calibration system that camera was markd, in this system, can reduce the cost of manufacture of mark target through this mark target, only gather the image through rotary mechanism's rotation and realize the quick high accuracy of camera demarcation when reducing the demarcation space.

The embodiment of the application is realized as follows:

the embodiment of the application provides a rotating mechanism for camera calibration, which comprises a bearing platform, a first rotating mechanism and a second rotating mechanism, wherein the first rotating mechanism is provided with a first rotating shaft; a second rotating mechanism having a second rotating shaft, the second rotating mechanism being mounted to the load-bearing platform, the second rotating shaft being perpendicular to the load-bearing platform, the first rotating mechanism being fixed to the second rotating mechanism, the first rotating shaft being perpendicular to the second rotating shaft and parallel to the load-bearing platform; and a camera mount fixed to the first rotating mechanism for mounting the camera, the camera mount being configured such that when the camera is mounted to the camera mount, an intersection of the axes of rotation of the first and second axes of rotation coincides with an optical center of the camera, an optical axis of the camera being coaxial with the first axis of rotation.

In an embodiment of the present application, the rotating mechanism further includes a connecting bracket, and the first rotating mechanism and the second rotating mechanism are fixed to the connecting bracket.

In this application embodiment, the above-mentioned linking bridge includes mutually perpendicular's horizontal stand and vertical support, the horizontal stand with vertical support fixed connection, first rotary mechanism is fixed in vertical support, second rotary mechanism connect in the horizontal stand with between the load-bearing platform.

The embodiment of the application provides a camera calibration system, which comprises a target carrier, a range extender, a camera, a rotating mechanism calibrated by the camera, a servo driver and electronic equipment, wherein the range extender is arranged between the camera and the target carrier; the camera is arranged on the rotating mechanism and electrically connected with the electronic equipment, the intersection point of the rotating shafts of the first rotating shaft and the second rotating shaft is superposed with the optical center of the camera, and the optical axis of the camera is coaxial with the first rotating shaft; the target carrier includes a planar surface for forming a target; the servo driver is electrically connected with the electronic equipment and used for driving the rotating mechanism to rotate and sending the position information of the rotating mechanism to the electronic equipment; the electronic equipment is used for calibrating the camera according to a target image and the position information, and the target image is obtained by shooting the target through the range-extended mirror by the camera.

The rotating mechanism and the system for camera calibration provided by the embodiment of the application comprise a bearing platform and a first rotating mechanism with a first rotating shaft; a second rotating mechanism having a second rotating shaft, the second rotating mechanism being mounted to the load-bearing platform, the second rotating shaft being perpendicular to the load-bearing platform, the first rotating mechanism being fixed to the second rotating mechanism, the first rotating shaft being perpendicular to the second rotating shaft and parallel to the load-bearing platform; and a camera mount fixed to the first rotating mechanism for mounting the camera, the camera mount being configured such that when the camera is mounted to the camera mount, an intersection of the rotating axes of the first rotating axis and the second rotating axis coincides with an optical center of the camera, and an optical axis of the camera is coaxial with the first rotating axis, so that the camera can photograph the enlarged target through the range-extending mirror to obtain a target image, and when the camera having a longer working distance is calibrated, a size of the target and a distance between the target and the camera are controlled, and a virtual target image is formed by rotation of the rotating mechanism, so that the camera photographs the virtual target image to complete calibration of the camera, without moving the target, only photographing an image during rotation of the rotating mechanism is required, and while difficulty in calibration of the camera is reduced, the camera calibration method has the advantages that the camera calibration with long working distance can be completed in a small calibration space, and the camera can be calibrated quickly and accurately.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the embodiments of the utility model. The objectives and other features of the utility model will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic view illustrating a rotation mechanism for camera calibration provided in an embodiment of the present application;

FIG. 2 is a schematic diagram illustrating a camera calibration system provided by an embodiment of the present application;

FIG. 3 is a schematic diagram illustrating a camera calibration system provided by an embodiment of the present application;

fig. 4 shows a schematic view of a target provided by an embodiment of the present application;

fig. 5 shows a schematic view of another target provided by embodiments of the present application;

fig. 6 shows a schematic view of yet another target provided by an embodiment of the present application;

fig. 7 shows a schematic view of some of the targets provided by embodiments of the present application;

FIG. 8 illustrates a schematic diagram of a board target provided by an embodiment of the present application;

FIG. 9 is a schematic diagram illustrating a virtual sphere provided by an embodiment of the present application;

FIG. 10 is a schematic diagram of a virtual sphere provided by another embodiment of the present application;

fig. 11 shows a projection schematic diagram of a virtual image of a marker provided in an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "middle", "upper", "lower", "front", "back", "vertical", "inner", "outer", etc. indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that are usually placed when the products of the present invention are used, and are only used for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.

Furthermore, the terms "horizontal", "vertical" and the like do not imply that the components are required to be absolutely horizontal or pendant, but rather may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "connected," and "connected" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The camera calibration is one of key technologies in the work of machine vision, photogrammetry, 3D imaging, image geometric correction and the like, and the main function of the camera calibration is to estimate internal and external parameters of the camera. The accuracy of the calibration result and the stability of the calibration algorithm directly affect the accuracy of subsequent work. In the calibration process of the camera, the working distance of the camera in normal use needs to be considered, and when the camera is calibrated, the distance between the camera and the target should be approximately the same as the working distance of the camera in normal use.

Currently, the calibration method related to the camera may be a planar target, and tool software based on the planar target is available, for example: matlab toolbox and Opencv toolkit software. In these methods, a planar calibration plate is placed in front of a camera at different positions to acquire multiple target images, so as to obtain calibration raw data with a large distribution range. The method needs to place the calibration plate at different positions and acquire target images for many times, or rotate the camera at different directions and acquire the target images for many times. This kind of mode is not only wasted time and energy, and when calibrating the camera, the distance between camera and the mark target need be roughly the same with the work when camera normal use, and when calibrating the longer camera of working distance like on-vehicle camera, the distance between mark target and the camera is great, leads to the operating space increase of demarcation, and the size of mark target also can be great, has not only increased the cost of manufacture of mark target, has also increased the degree of difficulty of demarcation.

Therefore, the inventor provides the rotating mechanism and the system for calibrating the camera, which can enable the camera to shoot the amplified target through the range extender to obtain a target image, control the size of the target and the distance between the target and the camera when calibrating the camera with longer working distance, and form a virtual target image through the rotation of the rotating mechanism, so that the camera shoots the virtual target image to complete the calibration of the camera without moving the target, reduce the difficulty of the calibration of the camera, simultaneously realize that the image is shot only in the rotating process of the rotating mechanism, and finish the quick and high-precision calibration of the camera in a smaller calibration space.

The rotating mechanism and the system for camera calibration provided in the embodiments of the present application will be described in detail through specific embodiments.

Referring to fig. 1, the present embodiment provides a rotation mechanism 100 for camera calibration, which includes a supporting platform 110, a first rotation mechanism 120, a second rotation mechanism 130, and a camera 140. Specifically, the second rotating mechanism 130 is installed on the bearing platform 110, the second rotating mechanism 131 is perpendicular to the bearing platform 110, the first rotating mechanism 120 is fixed to the second rotating mechanism 130, and the first rotating mechanism 121 is perpendicular to the second rotating mechanism 131 and parallel to the bearing platform 110.

In some embodiments, the load-bearing platform 110 may have a recess adapted to the second rotation mechanism 130, and the recess is used to mount the second rotation mechanism 130 on the load-bearing platform 110. In some embodiments, the bearing platform 110 and the second rotation mechanism 130 have spiral grooves with the same size, and the second rotation mechanism 130 can be mounted on the bearing platform 110 by screws.

As one mode, the first rotating mechanism 120 may be directly fixed to the second rotating mechanism 130, wherein the first rotating mechanism 120 may be fixed to the second rotating mechanism by an in-mold injection molding method. The first rotating mechanism 120 may also be fixed to the second rotating mechanism by screws, and the specific fixing manner is not limited herein.

Alternatively, the rotating mechanism 100 may further include a connecting bracket 150, and the first rotating mechanism 120 and the second rotating mechanism 130 are fixed to the connecting bracket 150. Specifically, the connecting bracket 150 includes a horizontal bracket 152 and a vertical bracket 151 that are perpendicular to each other, the horizontal bracket 152 and the vertical bracket 151 are fixedly connected, the first rotating mechanism 120 is fixed to the vertical bracket 151, and the second rotating mechanism 130 is connected between the horizontal bracket 152 and the bearing platform 110.

Specifically, the horizontal bracket 152 and the vertical bracket 151 may be synthesized as the connection bracket 150 by means of in-mold injection. The horizontal bracket 152 and the vertical bracket 151 can also be connected and combined into the connecting bracket 150 by means of screws.

The vertical bracket 151 may have a groove adapted to the first rotating mechanism 120, the first rotating mechanism 120 may be fixed to the vertical bracket 151 through the groove, and the horizontal bracket 152 may have a groove adapted to the second rotating mechanism 130, and the second rotating mechanism 130 may be fixed to the horizontal bracket 152 through the groove. As still another way, the vertical bracket 151 may have a spiral groove having the same size as that of the first rotating mechanism 120, the first rotating mechanism 120 may be fixed to the vertical bracket 151 by a screw, the horizontal bracket 152 may have a spiral groove having the same size as that of the second rotating mechanism 130, and the second rotating mechanism 130 may be fixed to the horizontal bracket 152 by a screw.

The camera 140 is mounted on the first rotating mechanism 120 through a camera mount (not shown), and the camera 300 is configured to shoot a virtual target formed by the target after being amplified by the range finder to obtain a target image, where the target image includes mark points in the virtual target. The camera mount is configured such that when the camera 140 is mounted to the camera mount, an intersection of the rotational axes of the first rotational axis 121 and the second rotational axis 131 coincides with an optical center of the camera 140, and an optical axis of the camera 140 is coaxial with the first rotational axis 121.

Specifically, the first rotating mechanism 120 may have a groove adapted to the camera fixing frame, and the groove is used to fix the camera fixing frame to the first rotating mechanism 120. The camera fixing frame and the first rotating mechanism 120 have the same size of spiral grooves, and the camera fixing frame can be fixed to the first rotating mechanism 120 by screws. The camera fixing frame and the first rotating mechanism 120 can also be fixed by in-mold injection.

The camera fixing frame may be a camera clip through which the camera is fixed to the camera fixing frame. The camera fixing frame can also be a groove, the groove is provided with a knob capable of adjusting the size of the groove, the size of the groove is adjusted through the knob to enable the groove to be matched with the size of the camera, and the camera is installed on the camera fixing frame in a mode that the camera is clamped into the groove.

Further, the direction of the optical axis of the camera 140 is determined by the rotation angle of the rotation mechanism 100, and the camera 140 rotates with the first rotation mechanism 120 and the second rotation mechanism 130 in a small range, which is equivalent to that the camera 140 does not rotate, and the target rotates on a large-range spherical surface, thereby solving the problems that a camera with a long working distance needs a long working distance, a large environment and a large target when the camera is calibrated.

Referring to fig. 2 and 3, a schematic diagram of a camera calibration system shown in conjunction with fig. 2 and 3 is shown. The present embodiment provides a camera calibration system, which may specifically include a rotation mechanism 100, a camera 140, a range-extended mirror 300, a target carrier 400, a servo driver 500 and an electronic apparatus 600. The range-extending mirror 300 is disposed between the camera 140 and the target carrier 400, the servo driver 500 is electrically connected to the electronic device 600, the servo driver 500 sends the position information of the rotating mechanism 100 to the electronic device 600, the electronic device 600 is configured to calibrate the camera 140 according to a target image and the position information, and the target image is obtained by shooting the target by the camera 140 through the range-extending mirror 300.

Further, the camera 140 may include a camera with a long working distance, such as a vehicle-mounted camera, which is not limited herein.

Further, the electronic device 600 may preset and store a preset amplitude, one or two servo drivers 500 may drive the first rotating mechanism 120 to rotate for one circle and drive the second rotating mechanism 130 to rotate within a preset amplitude range, or drive the first rotating mechanism 120 and the second rotating mechanism 130 respectively. For example, after the first rotation mechanism 120 is driven to rotate for one circle, the second rotation mechanism 130 is driven to rotate, or the second rotation mechanism 130 is driven to rotate first, and then the first rotation mechanism 120 is driven to rotate.

The servo driver 500 may transmit the rotation angle Φ of the first rotation mechanism 120 and the rotation angle θ of the second rotation mechanism 130 to the electronic apparatus as position information. The preset width is determined by the field angle of the camera to be tested, and is within a range of ± one-half of the field angle with the first rotation axis 120 as the central axis.

Further, the rotating mechanism 100 further includes a first rotary encoder installed on the first rotating mechanism 120 and a second rotary encoder installed on the second rotating mechanism 130, both of which are electrically connected to the servo driver 500, the first rotary encoder is used for obtaining the rotation angle position of the first rotating mechanism 120, and the second rotary encoder is used for obtaining the rotation angle position of the second rotating mechanism 130.

Further, the target carrier 400 includes a planar surface for forming the target 410. The target at least comprises one marking point, and the marking point can comprise one or a combination of more of but not limited to round spot, field lattice, BMW (horse-horse drawing), checkerboard and ChAruco. Referring to fig. 4, fig. 4 shows a schematic diagram of a target according to an embodiment of the present disclosure, in which the target 410 shows one or more circular spot shaped mark points 411A, and the circular spot shaped mark points 411A may be arranged in rows, columns, or matrixes, without limitation. Referring to fig. 5, fig. 5 is a schematic diagram of another target provided in the embodiment of the present application, in which the target 410 displays field-shaped mark points 411B, which may also be arranged in rows, columns, or matrixes, without limitation. Referring to fig. 6, fig. 6 is a schematic diagram of another target according to an embodiment of the present disclosure, in which the target 410 shows a field mark 411C and a circle spot 412C.

It is understood that the shape and number of the mark points displayed by the target 410 may be any one or combination of the patterns shown in a, b, c, d, e, and f in fig. 7, or a checkerboard pattern shown in fig. 8, which is not limited herein.

In the embodiment of the present application, the center of the target 410 and the center of the range-extending mirror 300 are on the same reference line, the optical axis of the range-extending mirror 300 is perpendicular to the plane, the distance between the range-extending mirror 300 and the target carrier 400 is smaller than the focal length of the range-extending mirror 300, so that the target can be enlarged by the range-extending mirror 300 to form a virtual target enlarged relative to the target, and the distance between the virtual target and the range-extending mirror 300 is greater than the focal length of the range-extending mirror 300, wherein the size of the virtual target is greater than the target, so that when a camera with a longer working distance, such as an on-board camera, is calibrated, a clear image of the target image can be obtained through the range-extending mirror 300 and also at a shorter physical distance, which not only meets the requirement of calibrating the camera at the working distance, but also controls the size of the target, the difficulty of camera calibration is reduced.

The camera 140 rotates along with the first rotating mechanism 120 and the second rotating mechanism 130, which is equivalent to that the camera 140 does not rotate, the target image rotates around the camera 140 in the rotating direction of the first rotating mechanism 120 and the rotating direction of the second rotating mechanism 130, and the motion track of the mark point forms a virtual spherical surface with the optical center of the camera 140 as the spherical center. The camera 140 takes a virtual image of the marker point through the range finder 300, so that the motion trajectory of the marker point forms a virtual sphere with the optical center of the camera 140 as the center of the sphere. After a plurality of target images collected by the camera are superposed, a target composite image containing a plurality of virtual images of the mark point can be obtained, and the image coordinates of the mark point in the target composite image can be determined according to the target composite image. Each mark point has a different distance from the optical center of the camera 140, so the radius of the virtual spherical surface formed by each mark point is different, if there are multiple mark points, multiple virtual spherical surfaces are formed, and the radius of each virtual spherical surface is the distance from the corresponding mark point to the optical center of the camera 140. It is understood that the number of the marker points included in the target image corresponds to the number of the virtual spherical surfaces.

Referring to fig. 9, fig. 9 shows a virtual sphere (fig. 9 left) and a projection diagram of the virtual sphere (fig. 9 right) formed when there is one marker 411. Fig. 10 shows that when the number of the marker points 411 is two, each marker point corresponds to one virtual sphere, the virtual sphere located at the upper part in fig. 10 corresponds to a marker point farther from the optical center of the camera, and the virtual sphere located at the lower part corresponds to a marker point closer to the optical center of the camera.

The camera 140 rotates with the first rotating mechanism 120 and the second rotating mechanism 130, which is equivalent to that the camera 140 does not rotate, and the target image includes a feature point that rotates around the camera 140 in the direction in which the first rotating mechanism 120 rotates and the direction in which the second rotating mechanism 130 rotates, and the motion trajectory of the feature point forms a spherical surface with the optical center of the camera 140 as the center of sphere. The camera 140 takes a virtual image of the feature point through the range finder 300, and therefore the motion trajectory of the feature point forms a spherical surface with the optical center of the camera 140 as the center of sphere as a virtual spherical surface.

Further, when the target includes at least two feature points, the camera 140 rotates with the first rotating mechanism 120 and the second rotating mechanism 130, which is equivalent to that the camera 140 does not rotate, the target image includes at least two feature points that rotate around the camera 140 in the direction of the rotation of the first rotating mechanism 120 and the direction of the rotation of the second rotating mechanism 130, and the motion trajectories of the at least two feature points form at least two spherical surfaces with the optical center of the camera 140 as the center of sphere. The camera 140 takes a virtual image of the feature point through the range finder 300, and therefore the motion trajectory of the feature point forms at least two virtual spherical surfaces with the optical center of the camera 140 as the center of sphere. It will be appreciated that there are a corresponding number of virtual spheres for the number of feature points included in the target image.

Please refer to fig. 11, fig. 11 shows a schematic projection diagram of a virtual image of a marker provided in an embodiment of the present application, where the marker 421 is on a latitude line 422 and a longitude line 423 on the image. When the first rotating mechanism 120 rotates, the motion trail of the virtual image of the feature point relative to the camera 140 is just coincident with the latitude line of the spherical coordinate system, when the second rotating mechanism 130 rotates, the motion trail of the virtual image of the feature point relative to the camera 140 is just coincident with the longitude line of the spherical coordinate system, and the longitude and latitude lines of the virtual spherical coordinate system formed by the rotation of the camera 140 around the first rotating mechanism 120 and the second rotating mechanism 130 can cover the whole spherical surface in the field of view of the camera 140, so that enough feature points are generated, and enough information is provided for the calibration of the camera.

Further, the plane of the target carrier 400 may be used to carry physical targets, or to display target images, or to carry electronic cards displaying target patterns.

In summary, the present invention provides a rotation mechanism and a system for camera calibration, and relates to the field of camera calibration technology. The rotating mechanism includes: a load-bearing platform; a first rotating mechanism having a first rotating shaft; the second rotating mechanism is provided with a second rotating shaft, the second rotating mechanism is arranged on the bearing platform, and the first rotating mechanism is fixed on the second rotating mechanism; the camera fixing frame is fixed on the first rotating mechanism and used for mounting the camera, so that the camera can shoot the amplified target through the range extender to obtain a target image, a virtual target image is formed through rotation of the rotating mechanism, the camera shoots the virtual target image to finish camera calibration, the target does not need to be moved, the camera calibration difficulty is reduced, meanwhile, the image is shot only in the rotating process of the rotating mechanism, and quick and high-precision calibration of the camera is finished in a small calibration space.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not necessarily depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims (10)

1. A rotation mechanism for camera calibration, comprising:

the bearing platform is arranged on the base plate,

a first rotating mechanism having a first rotating shaft;

a second rotating mechanism having a second rotating shaft, the second rotating mechanism being mounted to the load-bearing platform, the second rotating shaft being perpendicular to the load-bearing platform, the first rotating mechanism being fixed to the second rotating mechanism, the first rotating shaft being perpendicular to the second rotating shaft and parallel to the load-bearing platform; and

a camera mount secured to the first rotation mechanism for mounting the camera, the camera mount configured such that when the camera is mounted to the camera mount, the axes of rotation of the first and second axes of rotation intersect vertically, the intersection coinciding with the optical center of the camera, the optical axis of the camera being coaxial with the first axis of rotation.

2. The rotary mechanism of claim 1, further comprising an attachment bracket, wherein the first rotary mechanism and the second rotary mechanism are secured to the attachment bracket.

3. The rotating mechanism according to claim 2, wherein the connecting bracket comprises a horizontal bracket and a vertical bracket which are perpendicular to each other, the horizontal bracket and the vertical bracket are fixedly connected, the first rotating mechanism is fixed to the vertical bracket, and the second rotating mechanism is connected between the horizontal bracket and the bearing platform.

4. A camera calibration system comprising a target carrier, a range finder, a camera, a rotation mechanism as claimed in claim 1 or 2, a servo driver and electronics,

the range extender is arranged between the camera and the target carrier;

the camera is mounted on the rotating mechanism and electrically connected with the electronic equipment, the intersection point of the rotating shafts of the first rotating shaft and the second rotating shaft is superposed with the optical center of the camera, and the optical axis of the camera is coaxial with the first rotating shaft;

the target carrier includes a planar surface for forming a target;

the servo driver is electrically connected with the electronic equipment and used for driving the rotating mechanism to rotate and sending the position information of the rotating mechanism to the electronic equipment;

the electronic equipment is used for calibrating the camera according to a target image and the position information, and the target image is obtained by shooting the target through the range-extended mirror by the camera.

5. The system of claim 4, wherein the servo driver is configured to drive the first rotating mechanism and the second rotating mechanism to rotate within a preset range of amplitude, and to send a rotation angle φ of the first rotating mechanism and a rotation angle θ of the second rotating mechanism as position information to the electronic device.

6. The system of claim 5, wherein the predetermined range of amplitudes is determined by the field angle of the camera under test, and is ± one-half of the field angle range with the first rotation axis as the central axis.

7. The system of claim 5, wherein the rotating mechanism further comprises a first rotary encoder mounted to the first rotating mechanism and a second rotary encoder mounted to the second rotating mechanism, the first rotary encoder and the second rotary encoder each being electrically connected to the servo drive, the first rotary encoder being configured to obtain a rotational angular position of the first rotating mechanism, the second rotary encoder being configured to obtain a rotational angular position of the second rotating mechanism.

8. The system of claim 4, wherein an optical axis of the range mirror is perpendicular to the plane, and a distance of the range mirror from the target carrier is less than a focal length of the range mirror.

9. The system of claim 4, wherein the plane of the target carrier is used to carry a physical target, or to display a target image, or to carry an electronic card displaying a target pattern.

10. The system of claim 4, wherein the camera is a vehicle-mounted camera.

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