An algorithm is presented based on curvature variance to calibrate the lens distortion of digital camera.

By discussing the theory on camera calibration with vanishing points and analysing the errors resul- ted from calibration based on vanishing points,a novel approach to camera calibration by vanishing points in muhi images is proposed to acquire orientation parameters,even radial lens distortion and thereby to improve the precision of interior and exterior orientation parameters.

In 3D visual inspection applications, there usually exists a distortion error of the CCD camera s pin hole image of ellipse center.

For the slanting installation of optical system,the distortion error models are established and the simulations are done.

The ellipse curre equation of circular image is derived based on the theory of spatial analytic geometry and rotation matrix s representation with unit quaternion then a mathematical model of the distortion error is established which relates the distortion error to the foca length of the used CCD camera,the radius as well as the position and the attitude of the inspected circle directly.

A distortion measurement system,which is composed of high-precision goniometer,microscope measurement system,mini doublegrating interferometer,collimator and star point,is used to measure the distortion of the NFOV long-focus lens precisely.

The distortion measurement technology for digital video used computer-aided method was described based on building distortion model.