Multi-pattern Embedded Phase Shifting Using a High-Speed Projector for Fast and Accurate Dynamic 3D Measurement

Abstract

The goal of this study is to achieve high-speed and high-accuracy 3D measurement of a moving object using phase shifting. Phase shifting is a multi-shot method that uses structured light and enables high-accuracy and highresolution measurement with few projections. However, this method requires projecting a multi-tone pattern, which causes the projection speed of the projector to become a bottleneck. This in turn makes performing high-speed measurements difficult. Furthermore, because phase shifting is a multi-shot method, reduced measurement accuracy for moving objects becomes another concern. In this study, we overcome these problems by using a newly developed highspeed projector. First, this projector enables high-speed 3D measurement, as it can project 8-bit tone images at frame rates of 1000fps. Second, proposed method improves the measurement accuracy of moving objects by enabling phase unwrapping, while minimizing the number of projected patterns through pattern embedding. Through experiments, we demonstrate that, by embedding a Gray-code pattern within an interval of 100is, we can measure a object moving at a speed of approximately 30-50cm/s with a frame rate of 500fps and an average error of less than 1mm.