A linear self-calibration approach for camera focal length estimation

This paper comes up with a linear self-calibration approach for camera focal length estimation. Compared with other linear techniques, the advantage of this method is that no priori information of motion is needed. From the degenerated equations (one quadratic and two linear), the essential constraints are generated on calibration of camera intrinsic parameters. Thus the focal length of camera is conveniently obtained in closed form on the reliable assumption that only the focal length is unknown but constant, and the skew factor is zero. Synthetic object/image, real images of indoor and outdoor generic scenes and 3D model reconstruction are involved in our experiments to analyze the accuracy of the estimated focal length. The experimental results indicate that our proposed method is both robust and efficient.