1. An apparatus for calibrating a camera comprising: a camera configured to generate an image by photographing an environment quadrangle; an input unit configured to receive a segmentation diagonal ratio of the environment quadrangle; a memory configured to store a program for camera calibration; and a processor configured to perform camera calibration based on the program, wherein the program is configured to: extract diagonal parameters of a centered quadrangle from the image; estimate length of a projection center line based on the segmentation diagonal ratio of the environment quadrangle and the diagonal parameters of the centered quadrangle; estimate a projection angle corresponding to each diagonal of the centered quadrangle based on the length of the projection center line; estimate an angle between diagonals of a projection quadrangle based on the projection angle and an angle between diagonals of the centered quadrangle; estimate 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 estimate extrinsic and intrinsic parameters of the camera corresponding to the projection center point and the centered quadrangle.