INFLUENCE ANALYSIS OF THREE DIFFERENT CAMERA CALIBRATION METHODS ON A CAMERA-PROJECTOR MEASURING SYSTEM

Abstract

The challenges arising from mass production with high quality level require advanced error measurement systems and optical metrology systems. Nowadays, it is more frequent to find this type of controls at the manufacturing industry into the quality control procedures as long as the need for a faster capture speed and precision has increased. However, these techniques can be improved. The accuracy of 3D measurement systems formed by a camera-projector pair depends directly on the calibration procedure used. The projector is usually modelled as the inverse projection of a pin-hole camera, which presents the option to calibrate the system by two different approaches: as a whole system or separately. The most common approach is the use of a camera previously calibrated, followed by the calibration of the projector. Studies show that the uncertainty of the camera parameters from its calibration propagates to the projector parameters and several authors conclude that the three most widespread are: Tsai, Zhang and Direct Linear Calibration. The objective of this study is to have a clear comprehension of the relationships between the camera and projector parameters and of how uncertainty is propagated to the measurement system error. Therefore, the three calibration methods previously mentioned and some of them possible combinations are analyzed.