Design And Application Of Monocular Vision Measurement System Based On Reference Points In The Same Field Of View

A single camera model used to measure space three-dimensional coordinates was given in this paper. This model can be used to calibrate the camera parameters by using the perspective projection geometrical relationship and to build the relation between reference points and measured points based on the same field of view. Using the two restriction condition to set up a corresponding mathematical model and using the image coordinates of the monocular CCD camera, the three-dimension coordinate can be rebuilt.This model successfully solutes the problem that the coordinate measuring system of bomb-fall which bases on the principle of binocular vision may have some dead angles when the system is used in some complex areas such as mountainous regions and knaps. Additionally, the monocular vision system also solute the problem that binocular vision system needs to match the corresponding key points.The following work is mainly introduced in the paper:Design of the whole system. As an integrated computer vision system, this system includes a hardware system which can be divided into optics system, CCD sensing device and controlling & processing unit(computer), and a corresponding software for the image capturing and controlling. A fixed interconnection base is designed for the camera calibration, from which the camera achieves the image of the reference points, so as to calculate the internal-external parameter of the camera. Measurement model of the system and its calibration. The measurement method of the landing coordinate mainly contains three parts: (1) calibration of the camera parameter; (2) calibration of the plane in which the reference points and measured points locate; (3) build of the 3-D information. The calibration of the camera parameter sets up the relation between camera coordinate system and space coordinate system; the calibration of the plane in which the reference points and measured points locate builds the plane equation of the reference points of the space coordinate system; the build of the 3-D information realizes the transformation from 2-D computer image coordinate to 3-D information.Distortion of the image captured by CCD camera. The source of the system error,the effect on the system induced by the precision of the fixed interconnection base and the small hole camera model based on the lens radial distortion are introduced in this paper, in which the optical error and the photoelectrical error are analyzed and calculated. The camera parameters are calibrated at the condition of the lens radial distortion, through which the spin matrix, the translation matrix, the effective focal length f and the distortion factor k are calculated. The model built is proofed by experiments.