The Study Of Camera Calibration Based On Geometric Constraint Of Application Environment

The basic principle and main purpose of the camera calibration is to calculate the relationship between the three-dimensional object and the images which are obtained from the camera, to reconstruct and identify them. However, the relationship between the 3D points of the three-dimensional object and its 2D image points is determined by the geometric models of the camera which are called camera parameters. Calibrating a camera need precisely retrieve these parameters from the geometric models, optical parameters and physical location.In this paper, on the basis of wide range analysis and comparison about the existing classical methods on the conventional calibration, the relevant knowledge of the camera calibration was analyzed in-depth. In order to overcome the defects of the existing methods and combine the actual application environment, two different camera calibration methods, which base on two vanishing points constraint and single vanishing point constraint separately, are proposed for particular application scenarios. The calibration reference object is abandoned in these methods.Many vision-based automatic traffic monitoring and surveillance systems require a calibrated camera for computing speeds and classifications of tracked vehicles. A number of techniques, both manual and automatic, have been proposed for performing such calibration, yet these methods all have application limit. This paper presents a novel calibration method for a camera overlooking a traffic scene. The proposed approach automatically uses a set of parallel lane markings and the lane length to compute two orthogonal vanishing points to retrieve the camera parameters, The swing angle is also considered and included in this approach.The position and attitude parameter of a UAV at autonomous landing can be obtained from a calibrated camera. This paper offer a method to obtain UAV's flight parameters at auto-landing period based on single vanishing point constraint. According to the geometry features of landing ground to obtain vanishing point, the focal length function is established from the u and v axis scale of the image plane, then the position and attitude of UAV, are achieved from the calibration result.Experimental results of all proposed methods are presented that demonstrate the satisfied robustness and accuracy.