Geometric calibration of a camera or a stereoscopic vision sensor. (Optique Pour l'Ingénieur : Imagerie)

Orteu Jean-José

The geometric calibration of a camera consists in determining the existing mathematical relation between the coordinates of the 3D points of the scene observed and the 2D coordinates of their projection in the image (image-points). This step of calibration represents the initial point for several applications of the artificial vision, such as for instance: recognition and objects localization, control procedure for the dimensional measurement of cast parts, reconstruction of the environment for the navigation of a mobile robot, etc. Calibrating a camera is about choosing a model of camera a priori and then determining the parameters of that model. We will describe the main models of camera used as well as the main methods suggested in order to determine the parameters of the model chosen. To get tridimensional information, it is necessary to combine two cameras in order to constitute a stereoscopic vision sensor. The calibration of such a sensor is a specific problem and is also described.