A New Camera Calibration Method Based on Two Stages Distortion Model

To improve accuracy of computer visual inspection, a new camera calibration method is proposed. A mathematical camera model is set up based on theory of perspective projection and vector algebra, which takes into account both the first order radial distortion and disinterring distortion, and actual image point is regarded as the result point to which ideal image point is moved under the influence of radial and disinterring distortion one by one. Based on this model, disinterring distortion coefficients are solved firstly according to invariability in projection translation, and actual image points are corrected firstly to obtain intermediate image points. Then most of the external parameters are calibrated by using of RAC constraint, and other parameters are solved by nonlinear optimization method. Because the calibration of disinterring distortion coefficients is carried out independently, the calibration accuracy of CCD camera is increased remarkably with minimal impact upon efficiency. Both the simulative and real experiments show validity and practicability of this method.