Experiment on Precision of Camera Calibration of Non-metric Digital Cameras

Although many camera calibration methods for a non-metric digital camera have been proposed, there are few reports on the precision of calibration results. Therefore, we conducted a field experiment in order to examine the precision of calibration results of a non-metric digital camera. We adopted a calibration method using a set of calibration points distributed on the 2-D plane with no ground survey. Four non-metric digital cameras were calibrated in the filed experiment. A round of camera calibration utilized a set of eight convergent images acquired from eight different directions with four different camera frame rotation angles of 0°, +90°, +180° and −90° around the optical axis of the camera. 32 rounds of camera calibration for each camera were conducted. The experimental results demonstrate that dispersions of image distortions between obtained image distortion models cannot be neglected. The most part of the difference between estimated image distortions was the difference of the estimated position of the principal point, while the differences of another components of the image distortion model were small enough to be negligible. Furthermore, the experiment results show that the error estimates of the obtained camera parameters cannot indicate the precision of the obtained image distortion model.