The internal parameter calibration based on sub-pixel threshold segment algorithm

Abstract

The internal parameters is one of the important calibration parameters of visual measurement, which shows the accurate corresponding relation of the space point and the imaging point in computer image coordinate. Based on fiber optic imaging characteristics, the paper proposed the circular array targets and sub-pixel threshold segmentation algorithm to extract target feature points as to help the follow-up the accurate calibration of camera internal parameters. In contrast to some commonly uesd algorithm to extract the sub-pixel edge contour using interpolation and fitting, the proposed sub-pixel threshold segment algorithm is more small computational complexity and execution time. The experimental results show that the camera internal parameters have been obtained precisely with low execution time, which provides important guarantee for subsequent fiber length measurement based on visual measurement.