PROJECTIVE CALIBRATION OF A LASER-STRIPE RANGE FINDER

We discuss the calibration of a laser triangulation range system mount ed on a robot vehicle. Range sensing in general is briefly reviewed, f ollowed by a description of the Oxford/NEL range finder, a sensor moun ted on the Oxford AGV for use in object recognition and acquisition ta sks. Calibration of the range sensor is achieved by modelling it as a projectivity between two planes: the plane of the light stripe and the plane of the camera's detector array. The vehicle is driven to a know n location where there exists an arrangement of orthogonal planes whos e equations expressed in world coordinates have been premeasured accur ately. Known vehicle position relative to world coordinates, known sen sor position relative to vehicle coordinates, and a set of world plane to image point correspondences lead to an overdetermined set of linea r equations which can be solved to give the required eight unknown par ameters of the projectivity.