Designation & Implementation Of Camera Calibration And Distortion Image Correction Algorithm

Camera calibration and distortion image correction are important research topics in the areas of photo grammetry, visual inspection, computer vision, it have been greatly applied in the survey mapping, industrial control, navigation, military and other fields.The purpose of camera calibration is to build the relationship of three-dimensional objects and two-dimensional images and recover the information of space points by image. Wide-angle camera lens can get much information in large field of video features, but it has large distortion, and the distortion correction degree greatly affect the accuracy of the measurement system.The shape of deformed image correction is divided into two types:linear and nonlinear deformation, now more people research the correction of linear deformation and it is successfully resolved, however the nonlinear deformation is still an unsolved question. To address this issue, a method of nonlinear distortion correction is put forward in this paper. First of all, the principle of distortion is analysised. Then a dual high-end nonlinear equation is get by the distortion model. At last, the equation is solved by Newton iterative, it can calculate the corresponding images without distortion on the point, and the images are corrected well.In order to calibrate the extrinsic parameters of the camera on the intelligent car based on the visual navigation, a method of calibrate extrinsic parameters is introduced in this paper, the extrinsic parameters include pitch, yaw and roll angle and the height. First according to the principle of the camera lens projection, three parallel lines on the ground have the same vanishing point and different slopes in the image. First, because of the principle of perspective projection, the three parallels on the ground have the same vanishing point and different slopes. Then the expression of extrinsic parameters based on pixels is established by the relationship between of extrinsic parameters and vanishing point and slopes. At last, after mathematical analysis and coordinate transformation, the extrinsic parameters calibration of a vehicle-mounted cameras is completed.The great distortion of the wide-angle image is corrected using the above method, and the experimental results show that this approach can correct the distortion images quickly and accurately. It has been illustrated by the theoretical analysis and experiments that camera calibration and distortion image correction have some advantages, such as a principle of simple, easy to operate, high universality, the way to achieve diversity and integration in the automotive machine-vision system medium.