Using Geometric Constraints for Fisheye Camera Calibration

This paper presents a technique to linearly calibrate a fisheye camera using the fact that the distortion is in the radial direction (angle preservation on the X-Y plane). First, a linear equation based on this constraint is proposed for estimating intrinsic/extrinsic parameters. The skewness in the intrinsic parameters is assumed to be zero in this paper. Second, a pure rotation for the fisheye camera is applied to recover the depth of the principal plane. Last, distortion parameters are estimated based on least squares polynomial fitting. Our method provides a linear and closed-form solution. Besides, all the parameters can be estimated in the least squares sense, which largely reduces the errors created by the existing noise in the measurement. Our method can be applied for both circular and full-frame imaging with a fisheye lens. In comparison with classical techniques, our method does not require precise scene arrangement or any prior information such as the field-of-view of the lens or the location of the camera center.