Modelling and calibration of a precise optical positioning system based on four linear cameras

This study is intended for modeling and calibration of a precise optical positioning system for tracking 3D positions of remote targets in a large space. This system is made up of four linear cameras, which are equipped with cylindrical lenses. The four cameras are paired up as two identical groups. Each camera group is composed of two linear cameras that are packaged together with their imaging orientations normal to each other. The specially designed structure makes the system superior to existing three-linear-CCD-camera systems used for position tracking, in the efficiency of eliminating distortion of cylindrical lenses, a long-standing problem in precise calibration of linear cameras with cylindrical lenses. During the modeling and calibration process, each camera group is treated as an integrated 2D image sensor. A complete imaging model is established for each camera group, and the object-space error is used in calibration for obtaining optimal camera parameters. Simulative and real experiments have verified that, when the two cameras in each group have a good distortion consistency, the proposed calibration approach can effectively fit the model of linear cameras and correct the distortion of cylindrical lenses, thus leading to a significant improvement of positioning accuracy