A practical self-calibration method of rotating and zooming cameras

We propose a practical self-calibration method of rotating and zooming cameras. The problem of previous methods occurs when the camera motion is almost all zooming with very little rotation, which we call the degenerate configuration. In that case, the solutions become unstable and rotation angles cannot be calculated. When we adopt a pan-tilt camera (without z-axis rotation) and simplify intrinsic camera parameters, we can overcome the degenerate configuration and we can get a closed form solution. As pan-tilt cameras can be assumed for most stationary cameras (i.e. without translation) and not seem to affect the self-calibration, our method provides a simple, practical solution to the self-calibration problem. In addition, we introduce a nonlinear algorithm that adjusts not only camera parameters but also inter-image homography so that more accurate image registration is made possible. Simulations and experiments with real images are presented.