| Central catadioptric cameras are composed of the traditional camera and lens equipment.After ensure that the field of view has only a single point,in the central of catadioptric image planes,lines and spheres are all projected into conics.We call these conics as line images or sphere images.There is an imaginary conic in the central catadioptric image plane,called it as the image of the absolute conic(IAC).If we can get the image of the absolute conic using fitting conic,the camera intrinsic parameters can be obtained.This thesis has proposed two methods to evaluate the camera parameters.The first is to use the three lines of world,then we can get three line images.Every two line images intersect in two points,and the two points can compose a line.Then we can get three lines which intersect in a common point.The common point is the principal point of the image plane.For each line image,compute the polar line of the principal point,intersecting in two points.Then we get six points,and they are also in the IAC.We can use the six points to fitting the IAC,then using the method of cholesky to decompose the IAC and we can get the camera intrinsic parameters.The second is to use three spheres of world.The projection of sphere on the mirror surface is a small circle.First,computing the image of the sphere and the image of the sphere’s center.Secend,for each sphere image,computing the polar line of the image of its center,intersecting in two points.Then we also can get six points,and they are also in the IAC.We can use the six points to fitting the IAC,then using the method of Cholesky to decompose the IAC and we can get the camera intrinsic parameters.Compared to the first method,the result of the second method is more accurate,because the line images only have one third can be seen under the central catadioptric image plane.In the end,with a parabolic catadioptric camera,we demonstrate the two methods by both simulated experiment and real experiment,and compare with other methods. |
