CN217543873U - Three-dimensional target and system for camera calibration - Google Patents
Three-dimensional target and system for camera calibration Download PDFInfo
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- CN217543873U CN217543873U CN202220155141.0U CN202220155141U CN217543873U CN 217543873 U CN217543873 U CN 217543873U CN 202220155141 U CN202220155141 U CN 202220155141U CN 217543873 U CN217543873 U CN 217543873U
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Abstract
The application discloses a three-dimensional target and a system for camera calibration. Wherein the stereotarget includes: a plurality of collimator tubes; built-in patterns built in the plurality of parallel light pipes, wherein each parallel light pipe is internally provided with one built-in pattern, and the built-in patterns are vertical to the optical axis of the corresponding parallel light pipe; the collimator carrier is used for supporting the plurality of collimators so that the plurality of collimators are configured to correspond to the built-in patterns within the field of view of the camera to be calibrated. The three-dimensional target and the system using the scheme can be realized in a smaller space and only one target image is acquired to finish the quick and high-precision calibration of the camera.
Description
Technical Field
The present application relates to the field of camera calibration technologies, and in particular, to a three-dimensional target 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 camera calibration mainly has the function of estimating 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, a plurality of images need to be acquired, so that a calibration plate or a camera needs to be manually moved, when the calibrated camera has a longer working distance, such as a vehicle-mounted camera, a larger calibration plate needs to be manufactured and a larger calibration space is required in the calibration process, in actual application, time and labor are wasted, and the production cost is increased.
SUMMERY OF THE UTILITY MODEL
The application provides a three-dimensional mark target for camera calibration, and the three-dimensional mark target can be used for only acquiring a mark target image to realize rapid high-precision calibration of a camera in a very small working space.
The embodiment of the application is realized as follows:
the embodiment of the application provides a three-dimensional target for camera calibration, which comprises a plurality of parallel light pipes, built-in patterns and parallel light pipe carriers, wherein the built-in patterns are built in the parallel light pipes; the collimator carrier is used for supporting and mounting the plurality of collimators so that the plurality of collimators are configured to correspond to the built-in patterns within the field of view of the camera to be calibrated; the collimator comprises a tube body, a lens arranged in the tube body, a reticle, frosted glass and a light source, wherein the built-in pattern is manufactured on the reticle and arranged between the lens and the frosted glass, the built-in pattern is positioned at the focus of the lens, and light emitted by the light source sequentially passes through the frosted glass, the built-in pattern and the lens; the collimator carrier comprises at least one bearing plate and a fixing piece, wherein each bearing plate bears at least one collimator, and the collimator is fixed on the bearing plate by the fixing piece; the bearing plate comprises a bearing surface which can be a plane or a curved surface; the built-in pattern of the collimator comprises a circular spot, a grid of a field character, a BMW graph, a checkerboard, chArUco or other specially customized patterns. The built-in patterns of the plurality of parallel light pipes are used for forming a plurality of characteristic mark points; the characteristic mark points are used for forming image coordinates; and one of the parallel light pipes is used as a reference light pipe, and the world coordinates of the characteristic mark points are formed by utilizing the relative position relationship among the parallel light pipes.
Optionally, in the embodiment of the present application, the plurality of collimator positions are distributed and assembled such that the collimator built-in patterns are distributed at the angle of the maximum field of view of the camera to be calibrated as much as possible.
The embodiment of the application provides a system for camera calibration, and the system comprises a three-dimensional target, a camera and electronic equipment. The stereo target comprises a plurality of parallel light pipes, built-in patterns and parallel light pipe carriers, wherein the built-in patterns are arranged in the parallel light pipes, and each parallel light pipe is internally provided with one built-in pattern which is vertical to the optical axis of the corresponding parallel light pipe; the collimator carrier is used for supporting and mounting the plurality of collimators so that the plurality of collimators are configured to correspond to the built-in patterns within the field of view of the camera to be calibrated; the collimator comprises a tube body, a lens arranged in the tube body, a reticle, frosted glass and a light source, wherein the built-in pattern is manufactured on the reticle and arranged between the lens and the frosted glass, the built-in pattern is positioned at the focus of the lens, and light emitted by the light source sequentially passes through the frosted glass, the built-in pattern and the lens; the collimator carrier comprises at least one bearing plate and a fixing piece, wherein each bearing plate bears at least one collimator, and the collimator is fixed on the bearing plate by the fixing piece; the bearing plate comprises a bearing surface which can be a plane or a curved surface; the camera is used for shooting the three-dimensional target and collecting a target image, and the target image comprises the three-dimensional target and an image formed by combining built-in patterns of a collimator arranged on the three-dimensional target; the electronic equipment is used for extracting the characteristic mark points of the patterns built in the collimator in the target image according to the target image and determining the image coordinates of the characteristic mark points in the target image; the electronic equipment is also used for obtaining the longitude and latitude coordinates of each collimator relative to the reference collimator by taking one collimator as the reference collimator according to the relative position relationship among the plurality of collimators. Obtaining world coordinates of the feature mark points according to respective longitude and latitude coordinates of the multiple collimator tubes and a preset distance corresponding to each collimator tube, wherein the preset distance is the distance from a preset point in the axial direction of the collimator tube to the camera; the electronic equipment is further used for calibrating the camera according to the image coordinates and the world coordinates.
The embodiment of the application provides a three-dimensional target and a system for camera calibration. The stereo target comprises a plurality of parallel light pipes, built-in patterns and parallel light pipe carriers, wherein the built-in patterns are arranged in the parallel light pipes; the collimator carrier is used for supporting and mounting the plurality of collimators so that the plurality of collimators are configured to correspond to the built-in patterns within the field of view of the camera to be calibrated; the collimator carrier comprises at least one bearing plate and a fixing piece, wherein each bearing plate bears at least one collimator, and the collimator is fixed on the bearing plate by the fixing piece; the built-in patterns of the plurality of parallel light pipes are used for forming a plurality of characteristic mark points; and one of the parallel light pipes is used as a reference light pipe, and the world coordinates of the characteristic mark points are formed by utilizing the relative position relationship among the parallel light pipes. The camera acquires a target image by shooting the three-dimensional target, analyzes and processes the target image through electronic equipment to acquire image coordinates of the characteristic mark points, and can calibrate the camera by combining world coordinates, so that the camera can be calibrated quickly and with high precision by acquiring only one target image in a small working space.
Additional features and advantages of the present application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the embodiments of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof 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 shows a schematic diagram of a system for camera calibration according to an embodiment of the present application.
Fig. 2 shows a perspective target diagram for camera calibration according to an embodiment of the present application.
FIG. 3 is a schematic diagram of a built-in pattern of a collimator according to an embodiment of the present application.
Fig. 4 shows a longitude and latitude schematic diagram corresponding to a feature marker point obtained by extracting internal patterns of a plurality of collimator tubes from a target image after the target image is acquired according to 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 part", "upper", "lower", "front", "rear", "vertical", "inner", "outer", etc. indicate the position or positional relationship based on the position or positional relationship shown in the drawings, or the position or positional relationship which is usually placed when the product of the present invention is used, and are only for convenience of description of the present invention and simplification of description, but do not indicate or imply that the device or element referred to must have a specific position, 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 absolutely horizontal or hanging, but 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 explicitly stated or limited otherwise, the terms "disposed," "connected," and "connected" are to be construed broadly, and may be, for example, 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 meaning 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 recent years, vehicle-mounted module cameras are widely applied to the fields of panoramic vision, video monitoring, automobile navigation, virtual reality and the like due to the ultra-large view field range and the long working distance. However, the large field of view also brings about severe image distortion, which affects the visual perception of human eyes and the utilization of image information, so that the camera needs to be calibrated. On the other hand, because the working distance is longer, the distance between the camera and the target needs to be controlled within the normal working distance of the camera, so that the size of the target is larger, the manufacturing cost of the target is increased, and the difficulty of calibration is also increased.
The current method that has been developed is to use planar targets, and there are tool software based on planar targets, such as: 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. These methods are not suitable for some applications where it is necessary to quickly install the camera and perform calibration in a small working space, such as a mass production or camera assembly line.
Therefore, the inventor proposes the stereoscopic target and the system for camera calibration of the application. The camera shoots a three-dimensional target consisting of a plurality of collimator tubes, patterns arranged in the collimator tubes and collimator tube carriers within a short distance, a target image is collected, the target image is analyzed and processed through electronic equipment to obtain image coordinates of characteristic mark points, and the camera can be calibrated by combining world coordinates. Utilize the three-dimensional mark target formed by many collimator to mark the camera, shortened the camera and markd required working space, also saved the cost of preparation mark target simultaneously, through gathering three-dimensional mark target image, do not need removal mark target or camera to gather many mark target images, only gather a mark target image and can realize the quick and high accuracy of camera and mark, reduced the required time of mark by a wide margin, really played the effect of saving time and energy.
The stereoscopic target and the system for camera calibration provided in the embodiments of the present application will be described in detail by specific embodiments.
Referring to fig. 1, the present application provides a camera calibration system based on a stereo target, and specifically, the system may include a stereo target 100, a camera 110, and an electronic device 120. The stereo target 100 includes a plurality of collimator tubes, built-in patterns built in the plurality of collimator tubes, and collimator tube carriers, wherein a built-in pattern is built in each collimator tube, and the built-in pattern is perpendicular to an optical axis of the corresponding collimator tube; the collimator carrier is used for supporting and mounting the plurality of collimators, so that the plurality of collimators are configured to correspond to the built-in patterns within the field of view of the camera to be calibrated. The collimator carrier comprises at least one bearing plate and a fixing piece, wherein each bearing plate bears at least one collimator, and the collimator is fixed on the bearing plate by the fixing piece. The target image, which is an image formed by combining a stereo target and a collimator built-in pattern provided in the stereo target, is obtained by photographing the stereo target 100 through the camera 110.
The camera 110 may transmit the photographed target image to the electronic device 120, and the camera 110 and the electronic device 120 may be one device or two devices. The electronic device 120 extracts the feature mark points of the internal patterns of the collimator in the target image according to the target image, and determines the image coordinates of the feature mark points in the target image; and according to the relative position relationship among the plurality of parallel light pipes, one of the parallel light pipes is used as a reference light pipe, and the longitude and latitude coordinates of each parallel light pipe relative to the reference light pipe are obtained. Obtaining world coordinates of the feature mark points according to respective longitude and latitude coordinates of the multiple collimator tubes and a preset distance corresponding to each collimator tube, wherein the preset distance is the distance from a preset point in the axial direction of the collimator tube to the camera; and calibrating the camera 110 according to the image coordinates and the world coordinates corresponding to the acquired feature mark points.
Referring to fig. 2, the stereo target 100 includes a plurality of collimator 101 and a collimator built-in pattern 102. The plurality of collimator 101 are rigidly fixed together by a collimator carrier 103, or rigidly fixed together after fine adjustment, and the plurality of collimator are configured to correspond to the built-in pattern within the field of view of the camera by the collimator carrier 103.
Further, the collimator built-in pattern can be formed by a circular spot, a grid, a mare, a checkerboard, chAruco and other customized patterns with certain characteristics, and the plurality of collimator built-in patterns can be the same or different. Referring to fig. 3, fig. 3 is a schematic diagram illustrating an embodiment of a collimator built-in pattern 102 provided in the present application, wherein the collimator built-in pattern 102 may be displayed as a circular spot pattern 102A, a field-shaped pattern 102B, a mare pattern 102C, a checkerboard pattern 102D, and a chracuco pattern 102E, and may also display other customized patterns with certain features, which are not limited herein.
The relative position relationship among the multiple parallel light tubes can be determined according to the actual calibrated field angle of the camera, so that the built-in patterns of the parallel light tubes are distributed at the maximum field angle as far as possible. And taking one of the parallel light pipes as a reference light pipe, and obtaining the longitude and latitude coordinates of each parallel light pipe relative to the reference light pipe according to the relative position relationship among the parallel light pipes. Specifically, the longitude and latitude values of the plurality of collimator tubes can be set as required, and specifically, referring to fig. 4, a plane view in which the plurality of collimator tubes can be distributed in the three-dimensional target is shown. The latitude line 104 is a circle in the figure, and the longitude line 105 is a straight line passing through the center of the circle in the figure. Wherein, each collimator 101 can be placed at the intersection point of any latitude line and any longitude line.
To sum up, the three-dimensional target and the system for camera calibration provided by the embodiment of the application relate to the technical field of camera calibration. The stereo target comprises a plurality of parallel light pipes, built-in patterns and parallel light pipe carriers, wherein the built-in patterns are built in the parallel light pipes, and each built-in pattern is built in each parallel light pipe and is perpendicular to the optical axis of the corresponding parallel light pipe. The collimator carrier is used for supporting and mounting the plurality of collimators so that the plurality of collimators are configured to correspond to the built-in patterns within the field of view of the camera to be calibrated; the three-dimensional target is shot through the camera, and a target image is collected, wherein the target image comprises the three-dimensional target and an image formed by combining built-in patterns of a collimator arranged on the three-dimensional target. Extracting the characteristic mark points of the internal patterns of the collimator in the target image according to the target image through the electronic equipment, and determining the image coordinates of the characteristic mark points in the target image. And obtaining the world coordinates of the characteristic mark points according to the relative position relation among the parallel light pipes. And calibrating the camera according to the image coordinate and the world coordinate corresponding to the acquired feature mark point. The camera is calibrated by utilizing the three-dimensional target consisting of the plurality of collimator tubes, the working space used for calibration is greatly shortened, the cost for manufacturing the target is saved, meanwhile, the camera can be calibrated simply, quickly and highly accurately by acquiring the three-dimensional target image without moving the target or acquiring a plurality of target images by the camera and acquiring one target image, the time required by calibration is greatly shortened, and the effects of saving time and labor are really achieved.
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, it will be understood by those of ordinary skill in the art 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 (9)
1. A stereoscopic target for camera calibration, comprising:
a plurality of collimator tubes;
built-in patterns built in the plurality of parallel light pipes, wherein each parallel light pipe is internally provided with one built-in pattern, and the built-in patterns are vertical to the optical axis of the corresponding parallel light pipe;
the collimator carrier is used for supporting and installing the plurality of collimators so that the plurality of collimators are configured to correspond to the built-in patterns within the field of view of the camera to be calibrated.
2. The stereotarget of claim 1, wherein the collimator comprises a tube, a lens disposed within the tube, a reticle, ground glass, and a light source, wherein the built-in pattern is formed on the reticle and disposed between the lens and the ground glass, wherein the built-in pattern is located at a focal point of the lens, and wherein light emitted by the light source passes through the ground glass, the built-in pattern, and the lens in sequence.
3. The stereotarget of claim 1, wherein the collimator carrier comprises at least one carrier plate and a fixture, each carrier plate carrying at least one collimator thereon, the collimators being secured to the carrier plate by the fixture.
4. The stereotarget of claim 3, wherein the collimator carrier comprises at least one carrier plate, each carrier plate carrying at least one collimator thereon.
5. The stereotarget of claim 4, wherein the carrier plate comprises a bearing surface, the bearing surface being a flat surface or a curved surface.
6. The stereotarget of claim 1, wherein the collimator build-in pattern comprises a circle spot, a grid, a marquee, a checkerboard, or a ChArUco.
7. A system for camera calibration, comprising the stereoscopic target of any one of claims 1-6 and a camera, and further comprising an electronic device:
the stereo target comprises a plurality of parallel light pipes, built-in patterns and parallel light pipe carriers, wherein the built-in patterns are built in the parallel light pipes, each parallel light pipe is internally provided with one built-in pattern, the built-in patterns are perpendicular to the optical axis of the corresponding parallel light pipe, and the parallel light pipe carriers are used for supporting and mounting the parallel light pipes, so that the parallel light pipes are configured to correspond to the built-in patterns in the field range of the camera to be calibrated;
the camera is used for shooting the three-dimensional target and collecting a target image, and the target image comprises the three-dimensional target and an image formed by combining built-in patterns of a collimator arranged on the three-dimensional target;
the electronic device is used for calibrating the camera according to the target image.
8. The system of claim 7, wherein the collimator comprises a tube, a lens disposed within the tube, a reticle, ground glass, and a light source, the built-in pattern is etched on the reticle between the lens and the ground glass, the built-in pattern is located at a focal point of the lens, and light emitted from the light source passes through the ground glass, the built-in pattern, and the lens in sequence.
9. The system of claim 7 wherein said collimator carrier comprises at least one carrier plate and a fixture, each of said carrier plates carrying at least one collimator thereon, said collimators being secured to said carrier plate by said fixture.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202220155141.0U CN217543873U (en) | 2022-01-20 | 2022-01-20 | Three-dimensional target and system for camera calibration |
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| CN202220155141.0U CN217543873U (en) | 2022-01-20 | 2022-01-20 | Three-dimensional target and system for camera calibration |
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