The Research On Calibration Of The Non-Metric Digital Camera

In recent years, with the continuous progress of digital technology, computer performance will continue to improve and hardware prices decline, digital camera also gained popularity. Therefore, digital camera calibration gradually becomes the one of the hotspot in the field of computer vision and photogrammetry.Whether it was a former film camera or a popular digital camera, the image they have received must have a large or small distortion, which is caused by the camera imaging principle and the camera structure. So if you want to high precision measurement based on image, we must measuring and compensating camera distortion, also needs to be determined accurately out like some elements such as the principal point coordinates and the camera’s distance, in the research content mainly includes:1. Summarize the content and method of camera calibration. Based on the analysis of the principle of digital camera imaging, and the camera calibration items, namely photo orientation elements, exterior orientation elements and optical distortion difference are introduced in detail; according to different calibration, camera calibration points for traditional camera calibration method and self calibration method and like vanishing point of camera calibration method based on, and with the introduction of the various methods.2. Examples of the more commonly used three kind of camera calibration method that space resection based camera calibration method, based on the chessboard of the camera calibration method, like vanishing point of camera calibration method based on, and the principle and model of the three methods are introduced in detail.3. Research and development of camera calibration system and test. Will space resection based camera calibration method, based on the chessboard of the camera calibration method, based on like a vanishing point the camera calibration method and three kinds of camera calibration method to compile into a camera calibration system, and use with a camera, select three different focal length (24mm,35mm,50mm) the three methods experiment was carried out.4. The calibration results are compared and analyzed. According to the results obtained from the camera calibration, the results are compared and analyzed from the following aspects:(1) the results of distortion parameters are compared and analyzed. (2) comparative analysis of the results of aberration difference. (3) comparative analysis of the results of two camera calibration. (4) the influence of the number and distribution of the control points on the calibration results of the space resection method. (5) the effect of photo number and attitude on the chessboard method of camera calibration results. (6) the influence of the main distance on the camera distortion. (7) the comparative analysis of single space resection and multiple space resection. Among them, in the single space resection and multiple space resection of the comparative analysis, from the addition of distortion correction and do not join the distortion correction two aspects of the analysis.Through the comparative analysis of the calibration results obtained:radial distortion influence on the calibration result is greater than the focal length of the eccentric distortion; with the increase of camera lens distortion parameters more and more small; the distortion of the optical changes like changes in the two principal distance curve; distance closer to the center of the image point coordinates, the distortion is more small; the number and distribution of control points will have an impact on the space resection method of camera calibration results, so the choice of control points, the best number of about 10, the distribution is evenly distributed throughout the photo; photo pose and photo number has a certain effect on the chessboard method of camera calibration. Take photos when you select multiple camera angles, the number of photos to take the best in 15; it also proved that the camera technology developed today, the space resection method calibration accuracy There was a slightly higher than based on vanishing point method and method based on checkerboard; behind the space rendezvous to than monolithic rear space rendezvous and high reliability.