A novel approach to planar camera calibration

Camera calibration is an important step in 3D reconstruction of scenes. Many natural and man made objects are circular and form good candidates as calibration objects. We present a linear calibration algorithm to estimate the intrinsic camera parameters using at least three images of concentric circles of unknown radii. Novel methods to determine the projected center of concentric circles of unknown radii using the projective invariant, cross ratio, and calculating the vanishing line of the circle are proposed. The circular calibration pattern can be easily and accurately created. The calibration algorithm does not require any measurements of the scene or the homography between the images. Once the camera is fully calibrated the focal length of zooming cameras can be estimated from a single image. The algorithm was tested with real and synthetic images with different noise levels.