Calibration of Ring Multicamera System With Transparent Target for Panoramic Measurement

The calibration of a multicamera system is a prerequisite for high-accuracy measurement. In this study, a method for calibrating a ring multicamera system with a transparent target combined with digital image correlation (DIC) technology is proposed to achieve panoramic dynamic and static measurement of the object. The transparent target is placed in the middle of the ring camera array, and the target can be driven by the turntable to calibrate multiple cameras simultaneously. A complete refraction correction model is built on the transparent side of the target, and the corrected calibration data are integrated into the multicamera DIC system. The global optimization further improves the overall calibration accuracy of the system. Special markers are attached to the target surface to automatically identify the refractive and nonrefractive surfaces of the target. This type of camera can establish a coordinate relationship with the cameras on the other side of the target although no overlapping field of view exists between adjacent cameras on the same side of the target. The calibration data are analyzed, and dynamic and static experiments are implemented to verify the measurement accuracy of the system. All experimental results show that the calibration and measurement accuracies of the proposed method are high, and the system can be fully used for high-precision panoramic dynamic and static measurements.