Calibration Of Camera By Using The Properties Of Pole-polar And Conjugate Diameters In Two Planar Mirrors

Computer vision has high requirements for the accuracy of 3D reconstruction relative to the camera intrinsic parameters.In general,the double plane mirrors catadioptric system consists of two plane mirrors and a traditional camera.The imaging system can generate multiple views of an object,and the multiple views of the object can not only complete the camera calibration,but also reconstruct a more accurate three-dimensional model through them.A double plane mirrors catadioptric system is used to generate five views of an object.Five points are extracted on the perspective images,one of which is the point on the real object,and the other four points are the points on the four virtual objects.These five points form a conic,which is the image of the circle in space.By analyzing the geometric relationship of the five points,two linear methods are proposed to calibrate the camera.The two calibration methods are as follows:According to the principle of polar and projective invariance,the image of the center of a circle can be solved by using five corresponding points.A vanishing line on the image plane can be obtained by using the image of the center of the circle.The intersections of vanishing line and circular image are two imaged circular points.On the basis of obtaining the image of the center of the circle,according to the definition of antipodal image points and the projective invariance,the two pairs of antipodal image points can be determined in the image plane.The two pairs of antipodal image points are images of four vertices of a rectangle.And the two opposite sides of the rectangle are parallel to a pair of conjugate diameters of the circle,respectively.Based on the properties of conjugate diameters,a pair of orthogonal vanishing points can be obtained on the image plane.In the simulation experiment,the accuracy of the proposed algorithm can be verified by the noise sensitivity test.In the real experiment,the object is reconstructed in three dimensions through its five silhouette contour,and the results of three-dimensional reconstruction show that the proposed method is feasible and effective.