Method for obtaining focal length of zoom camera containing first-order radial distortion

Abstract

The invention discloses a method for obtaining the focal length of a zoom camera containing first-order radial distortion. The method comprises the following steps that: obtaining two object points ofwhich the physical coordinates are known to independently serve as a first control point and a second control point, regulating the gesture of the zoom camera to enable a first image point and a camera main point to coincide, and enabling the second control point to be positioned in the field of view of the zoom camera, wherein the first image point is the image point of the first control point in an imaging plane; observing the pixel coordinate of a distortion image point in the imaging plane to obtain the radial length of the distortion image point, and according to the radial length of thedistortion image point, obtaining the radial length of the second image point, wherein the distortion image point is the image point, which contains the first-order radial distortion, of the second control pint in the imaging plane, and the second image point is the image point, which does not contain the first-order radial distortion, of the second control point in the imaging plane; and according to a spatial position relationship, utilizing the zoom camera, the physical coordinates of two control points and the radial length of the second image point, obtaining the focal length of the zoomcamera. By use of the method, accuracy for obtaining the focal length of the zoom camera can be improved.

Description

technical field [0001] The invention belongs to the field of camera calibration, and more specifically relates to a method for obtaining the focal length of a zoom camera with first-order radial distortion. Background technique [0002] Zoom cameras have the ability to work normally under various field of view, depth of field and lighting conditions, and have been widely studied and applied in the fields of visual tracking, depth reconstruction and security monitoring. In practical applications, the focal length of the zoom camera will change, and other camera internal parameters do not change with the change of the camera focal length. Therefore, other camera internal parameters except the camera focal length can be accurately calibrated in the experimental environment in advance, while the camera focal length is It needs to be re-acquired in practical applications. [0003] The S.Gedikli method can calculate the focal length of the zoom camera through two control points, ...

AI Technical Summary

Problems solved by technology

[0003] The S.Gedikli method can calculate the focal length of the zoom camera through two control points, but the S.Gedikli method does not take into account the distortion of the camera and the situation that the width and height of the pixel are not equal, so it is obtained by the S.Gedikli method in practical applications There will be a large error in the focal length of the camera

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