Research On Camera Calibration Technology In The Asphalt Pavement Surface Inspection

This dissertation was firstly discussed the radical theory of the camera calibration in detail, including the measurement principal of the laser triangulation, the ideal mathematics model of the camera, the actual mathematics model of the camera and the important significance of the camera calibration. Secondly, introduced several common camera calibration methods, including the closed-form solution, the direct nonlinear minimization, the two-step method and the two-plane method. Otherwise, discussed their virtues and flaws, thirdly debated a new camera calibration method, the nonlinear iterative algorithm, and use this method to calibrate the long-focus and short-focus camera, and compare the calibration result with that of the two-step method. In the end, gain the conclusion that, for the sake of this item, we should adopt this method to calibrate the short-focus camera in the lab, and this method is also valid to the long-focus camera. Finally designed two types of sensor and analyze their characteristic such as their metrical range and resolving power. This dissertation was also discussed how to adopt the II-type sensor to measure the structure depth of the road.In the dissertation a proper calibration means to calibrate the wide-range-lens camera accurately and rapidly was used. It meets the need of the item and can be divided into two steps. The first step consists of using a non-iterative algorithm to directly compute a closed-form solution for all the external parameters and some major internal parameters based on a distortion-free camera model. The second step is a nonlinear optimization based on a camera model that incorporates distortion using the first step as initial guess. Otherwise, the two types of cameras in the lab. the I-type sensor to measure the track of the asphalt road, and the II-type sensor to measure the structure depth of the asphalt road and rebuild the road surface.