Method for linearly solving intrinsic parameters of camera by aid of three tangent circles

Abstract

The invention relates to a method for calibrating a camera by means of solving two vanishing points in orthogonal directions by the aid of three externally or internally tangent circles on a plane. The method includes that three images are taken for a target from different directions, equations of various curves on the images and coordinates of tangent points of the images are extracted, projection coordinates of centers of the various circles are solved, a corresponding point of an image of each tangent point relative to an image of each circle center on a projection curve and a tangent line of the image of the tangent point and the corresponding point relative to the projection curve are solved, and the two vanishing points in the orthogonal directions are solved according to a principle of cross-ratio invariance and intersection points of the tangent lines; and the two vanishing points in the two orthogonal directions on the three images are computed, constraint equations of intrinsic parameters of the camera are established, and the five intrinsic parameters of the camera are linearly solved. The method has the advantages that full-automatic calibration can be realized owing to the target, and errors caused by measurement in a calibration procedure are reduced; and as the quadratic curves are concise and comprehensive elements, the calibration precision is improved in the camera calibration procedure.

Description

technical field [0001] The invention belongs to the field of computer research, and relates to three tangent circular targets used for solving internal parameters of a camera. Using any three mutually circumscribed circles or two circumscribed and inscribed circles as a calibration template, the internal parameters of the camera are determined linearly by solving the vanishing points in the orthogonal direction on the three images. 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 came...

AI Technical Summary

Problems solved by technology

[0003] Although the traditional camera calibration method can obtain high precision, it is difficult to make the calibration block and it is not easy to operate

Aiming at this problem, the document "A flexible new technique for camera calibration", (Zhengyou Zhang, IEEE Transactions on Pattern Analysis and Machine Intelligence, vol.22, no.11, pp.1330-1334, 2000.) proposes a planar template Instead of the traditional calibration block method, this method is simple, convenient, low cost, and can obtain high accuracy, but it needs to accurately locate the physical coordinates of the dot matrix on the template

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