Camera external parameter calibration method of multi-camera system

A calibration method and multi-camera technology, applied in the field of computer vision, can solve problems such as complex calibration process, and achieve the effects of high calibration accuracy, simple production and high calibration efficiency

Inactive Publication Date: 2017-09-08
XIDIAN UNIV
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Problems solved by technology

[0007] The purpose of the present invention is to provide a method for calibrating extrinsic camera parameters of a multi-camera system, aiming at solving the problems of complex calibration process and accumulated errors in existing multi-camera extrinsic parameter calibration methods

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  • Camera external parameter calibration method of multi-camera system

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Embodiment 1

[0024] In the camera extrinsic parameter calibration method of the multi-camera system, the existing method of using a ball as the calibration object rarely involves the calibration of the multi-camera extrinsic parameters, while the early method needs to use an accurate three-dimensional calibration object. The disadvantage is that precise calibration objects need to be used, and the calibration cost is relatively high; in the calibration method using planes as calibration objects, since the plane cannot be visible to multiple cameras in all directions at the same time, it is necessary to first obtain the coordinates of each camera relative to different world coordinate systems. External parameters, and then transform the external parameters relative to different world coordinate systems into external parameters relative to the same world coordinate system. The calculation process is complicated and has cumulative errors.

[0025] For this reason, the present invention propose...

Embodiment 2

[0035] The camera extrinsic parameter calibration method of the multi-camera system is the same as in embodiment 1, wherein, in step (1), the quadratic curve matrix of the spherical projection taken by each camera in the multi-camera system is obtained by fitting, including:

[0036] Assuming that there are M cameras in the multi-camera system, each camera in the multi-camera system shoots three spherical images with different spatial positions and known radii from different angles of view, see figure 2 , where on the image plane corresponding to the i-th camera, the edges of the three shot spherical projections are obtained, and the sub-pixel edge extraction algorithm is used to extract the edge points of the three shot spherical projections, and the i-th shot is obtained through the quadratic curve fitting algorithm The conic matrices of three spherical projections captured by a camera are denoted as For other cameras in the multi-camera system, the quadratic curve method ...

Embodiment 3

[0041] The camera extrinsic parameter calibration method of the multi-camera system is the same as embodiment 1-2, the specific steps of the non-homogeneous coordinates of the center of the three shooting spheres in the camera coordinate system of each camera in the multi-camera system described in step (2) Including:

[0042] 2.1 Clarify the relationship between the spatial spherical projection and the internal parameters of the camera: see image 3 , using the plane homography, the relationship between the conic curve of the shooting spherical projection and the internal parameters of the camera, the relationship between the camera coordinate system and the world coordinate system, the origin of the camera coordinate system is the camera optical center O c , let the origin of the world coordinate system be O w , the world coordinate system is in O w -X w Y w Z w Indicates that O w Z w Axis, the center of the sphere projected through the space that forms the camera ima...

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Abstract

The invention discloses a camera external parameter calibration method of a multi-camera system for solving the problems that a three-dimensional precise calibration object is difficult to manufacture, the efficiency of a multi-camera external parameter calibration process is low, and that accumulative errors are generated in the existing method. The method comprises the following steps: performing fitting to obtain quadratic curve matrixes of shooting ball projections of cameras; solving inhomogeneous coordinates of three spherical centers in a camera coordinate system; establishing a world coordinate system in which the three spherical centers are located on the same plane through the plane where the three spherical centers are located and the positions of the spherical centers; solving external parameters of a plurality of cameras in the world coordinate system in which the three spherical centers are located on the same plane, and accomplishing the external parameter calibration of the cameras in the multi-camera system, wherein the two coordinate systems are overlapped. By adoption of the camera external parameter calibration method disclosed by the invention, the external parameters of the plurality of cameras in the same world coordinate system are calculated quickly, conveniently and accurately without requiring more conversion, no accumulative error is generated, and the camera external parameter calibration precision is high. The camera external parameter calibration method is applied to the fields of image measurement, three-dimensional reconstruction, unmanned aerial vehicle navigation, etc.

Description

technical field [0001] The invention belongs to the technical field of computer vision, and mainly relates to space target positioning and photogrammetry, in particular to a method for calibrating external camera parameters of a multi-camera system. It is used in image measurement, UAV navigation, 3D reconstruction and other fields. Background technique [0002] Camera calibration is a fundamental step in recovering object 3D geometry information from 2D images. Currently, a variety of camera calibration methods have been proposed. Camera calibration is divided into camera internal parameter calibration and camera external parameter calibration. Camera internal parameters describe the internal geometric structure parameters of the camera, while camera external parameters describe the rotation and translation relationship between the camera coordinate system and the established world coordinate system. Currently, camera calibration methods mainly include: [0003] One is t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06T7/80
CPCG06T7/85G06T2207/30204
Inventor 贾静李小平张逸勇邱世赟布芳
Owner XIDIAN UNIV
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