Computer vision researchers have proved the feasibility of camera self-calibration —the estimation of a camera's internal parameters from an image sequence without any known scene structure. Various self-calibration algorithms have been published. Nevertheless, all of the recent sequential approaches to 3D structure and motion estimation from image sequences which have arisen in robotics and aim at real-time operation (often classed as visual SLAM or visual odometry) have relied on pre-calibrated cameras and have not attempted online calibration.