Calibration Method for Ultra‐Wide FOV Fisheye Cameras Based on Improved Camera Model and SE(3) Image Pre‐Correction

ABSTRACT The severe radial distortion of ultra‐wide field of view (FOV) fisheye camera results in poor model fitting and challenges in calibration board detection. In this paper, a novel calibration method for ultra‐wide FOV fisheye cameras is proposed based on improved camera model and SE(3) image pre‐correction. Initially, a method to extend the maximum fitting FOV of the camera model to over 180 degrees is proposed. Subsequently, a calibration board detection approach is proposed using SE(3) image pre‐correction. Specifically, image pre‐correction is incorporated into the camera calibration process, utilizing SE(3) to define the pre‐correction plane. Calibration boards are detected within the pre‐corrected images, enhancing the reliability, accuracy and speed of board detection in distorted images, consequently increasing the control point's maximum FOV. Lastly, the improved camera model and SE(3) image pre‐correction are integrated into a feedback‐based camera calibration system for ultra‐wide FOV fisheye cameras. Operating with real‐time or offline video streams as input, this system autonomously selects calibration key frames, optimizes camera parameters and calibration board poses in real‐time. Simulation and real‐world experiments verify the effectiveness of the proposed method, leading to a 62% increase in the achievable maximum FOV.