1. A method for calibrating a camera comprising: (a) obtaining a two-dimensional (2D) homography that maps each of parallelograms projected onto two images taken by the camera into a rectangle, wherein the 2D homography is defined as a rectification homography and wherein new cameras that have virtual images are defined as rectified cameras and a new infinite homography is generated between the two rectified cameras under the assumption that all the edges of each parallelogram are on the same planes of 3D space, the virtual images being transformed from original images using the rectification homography; (b) obtaining an original infinite homography by using the correlation among the new infinite homography, the rectification homography and the original infinite homography; and (c) obtaining intrinsic camera parameters based on the correlation between the original infinite homography and the intrinsic camera parameters, thereby calibrating the camera.