Solving camera intrinsic parameter by using image of center of sphere and orthogonality

Abstract

The invention relates to a method for solving camera intrinsic parameter by using the image of the center of a sphere and orthogonality. The method comprises: firstly, taking three pictures of a calibrated sphere from different directions and reading the images, extracting coordinates of three quadratic curves from the three images; according to imaging process of the sphere and the center of the sphere under the camera, solving to obtain image coordinates of three centers of spheres, and according to projections of the centers of spheres, calculating end points on orthogonal directions, and finally by using the end points on orthogonal directions, solving images of absolute conics, and according to the images of quadratic curves, and solving a constraint matrix of camera intrinsic parameters, so as to obtain the camera intrinsic parameter. By using the spheres which are targets, full-automatic calibration can be realized, and errors caused by measurement in a calibration process are reduced. Since the quadratic curve is a simpler and more global element, and projection contours of the spheres can be completely extracted from the images, calibration precision is improved in a camera calibration process.

Description

technical field [0001] The invention belongs to the field of computer research and relates to a method for solving internal parameters of a camera. Using the sphere in space as a calibration template, according to the projection of the center of the sphere, the vanishing point in the orthogonal direction is obtained, and the internal parameters of the camera are solved linearly. Background technique [0002] One of the basic tasks of computer vision is to restore the geometric information of objects in three-dimensional space from the two-dimensional image information obtained by the camera, so as to recognize and reconstruct the geometric shape of objects in three-dimensional space. In this process, the relationship between the three-dimensional geometric position of the spatial object point and its corresponding point in the image must be determined, and this relationship is determined by the geometric model of the camera imaging, and the parameters of these geometric mode...

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Problems solved by technology

The document "Camera Calibration Algorithm Based on Spheres under Rank 1 Constraints", (Jia Jing, Wu Chengke. Journal of Xidian University (Natural Science Edition), 2013, 40 (2)) proposes to use a camera based on spheres under rank 1 constraints Calibration algorithm, which explains the geometric meaning of the constraint, combines the plane with the sphere, which is also a linear algorithm, but the calculation process needs to be optimized, and the calculation is relatively large

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