1. An apparatus for calibrating a camera comprising: a camera configured to generate an image quadrangle in an image by photographing an environment quadrangle; an input unit configured to receive a segmentation diagonal ratio of the environment quadrangle; a processor; a non-transitory computer-readable medium whose contents, when executed by the processor, cause the processor to perform camera calibration operations, the camera calibration operations comprising: generating a centered quadrangle using first and second vanishing lines, the first and second vanishing lines connecting a center of the image to a pair of vanishing points; extracting diagonal parameters of the centered quadrangle from the image estimating a length of a projection center line based on the segmentation diagonal ratio of the environment quadrangle and the diagonal parameters of the centered quadrangle; estimating a projection angle corresponding to each diagonal of the centered quadrangle based on the length of the projection center line; estimating an angle between diagonals of a projection quadrangle based on the projection angle and an angle between diagonals of the centered quadrangle; estimating a projection center point based on the projection angle, the angle between diagonals of the centered quadrangle and the angle between diagonals of the projection quadrangle; and estimating extrinsic and intrinsic parameters of the camera corresponding to the projection center point and the centered quadrangle, wherein the centered quadrangle is generated by: detecting first extension intersection points, the first extension intersection points being intersections of extension lines of each side of the image quadrangle and a segment connecting two vanishing points; detecting second extension intersection points, the second extension intersection points being intersections of the vanishing lines and one of the extension lines; and detecting third extension intersection points, the third extension intersection points being intersections of the centered vanishing lines and lines connecting the first and second extension intersection points, and wherein the second and third extension intersection points are vertices of the centered quadrangle.