Real-time three-dimensional shape measurement of moving objects without edge errors by time-synchronized structured illumination.

Structured-light illumination is a process of three-dimensional imaging where a series of time-multiplexed, striped patterns are projected onto a target scene with the corresponding captured images used to determine surface shape according to the warping of the projected patterns around the target. In a real-time system, a high-speed projector/camera pair is used such that any surface motion is small over the projected pattern sequence, but regardless of acquisition speed, there are always those pixels near the edge of a moving surface that capture the projected patterns on both fore- and background surfaces. These edge pixels then create unpredictable results that typically require expensive processing steps to remove, but in this Letter, we introduce a filtering process that identifies motion artifacts based upon the discrete Fourier transform applied to the time axis of the captured pattern sequence. The process is of very low computational complexity, and in this Letter, we demonstrate that in a real-time structured-light illumination (SLI) system, the process comes at a cost of 15 frames per second (fps), where our SLI system drops from 180 to 165 fps after deleting those edge pixels where motion was detected.