On-spot camera calibration method based on flexible planar target

A flexible planar target method was proposed to perform on-spot camera calibration. In this method, only several characteristic points with known 3D coordinates are needed to be preset on the planar target, and among these preset characteristic points, the ones which are collinear could determine a straight line, so a number of straight lines can be determined. Furthermore, under the perspective projecting transformation, straight line and the intersection point of two straight lines are invariables. So, based on the above mentioned properties, a great amount of points which differ from the preset characteristic points on the planar target can be obtained for on-spot camera calibration. Detailed error analysis of the obtained calibration points was conducted based on error propagation law. A real flexible planar target, which is of the size of 100 mm×100 mm and the accuracy of 0.01 mm, was made to perform the experiments of on-spot camera calibration, and the calibration accuracy is 0.032 mm.