Optimization of influencing factors of camera distortion calibration

The camera distortion is affected by many factors such as the calibration environment, the size of the calibration object, and the number of captured images, which lead to reducing the measurement accuracy of image detection. The experimental analysis of the calibration accuracy is carried out from both the number of photos and the area division of the calibration board. The experiment of the number of photos used three different sizes of calibration board. The number of pictures with the effective focal length of the photo calibration tends to be stable is 10-18. Another experiment was used cross-division to calculate of distortion coefficient and distortion correction by cross-ratio invariance. Take the points which on the diagonal of Calibration plate image after distortion correction to calculate the average linear offset. The linear offset without partition is 0.8651 and 0.6439. And the linear offset after the sub-region is 0.6439 and 0.2817. Therefore dividing the area can improve the accuracy of distortion correction.