Robust calibration of a reconfigurable camera array for machine vision inspection (RAMVI): Using rule-based colour recognition

This paper describes a Reconfigurable Array for Machine Vision Inspection (RAMVI) that is able to produce spatially-accurate images combining information obtained from several cameras. Automatic camera calibration is essential for minimizing the changeover time required to reconfigure the array. This paper describes an automatic calibration method that uses a colour coded calibration grid (CCG) to determine the field of view of each camera relative to the other cameras. Since colour is integral to the calibration process, robust colour recognition is essential, particularly since several cameras are involved. Hence, a rule-based colour recognition methodology is described. Results are presented demonstrating the effectiveness of this approach under varying lighting conditions.