Novel calibration method for structured-light system with an out-of-focus projector

A structured-light system with a binary defocusing technique has the potential to have more extensive application due to its high speeds, gamma-calibration-free nature, and lack of rigid synchronization requirements between the camera and projector. However, the existing calibration methods fail to achieve high accuracy for a structured-light system with an out-of-focus projector. This paper proposes a method that can accurately calibrate a structured-light system even when the projector is not in focus, making it possible for high-accuracy and high-speed measurement with the binary defocusing method. Experiments demonstrate that our calibration approach performs consistently under different defocusing degrees, and a root-mean-square error of about 73 μm can be achieved with a calibration volume of 150(H) mm×250(W) mm×200(D)mm.