Triangulation-based camera calibration for machine vision systems

This paper describes a camera calibration procedure for stereo-based machine vision systems. The method is based on geometric triangulation using only a single image of three distinctive points. Both the intrinsic and extrinsic parameters of the system are determined. The procedure is performed only once at the initial set-up using a simple camera model. The effective focal length is extended in such a way that a linear transformation exists between the camera image plane and the output digital image. Only three world points are needed to find the extended focal length and the transformation matrix elements that relates the camera position and orientation to a real world coordinate system. The parameters of the system are computed by solving a set of linear equations. Experimental results show that the method, when used in a stereo system developed in this research, produces reasonably accurate 3-D measurements.