Dual-frequency fringe projection for 3D shape measurement based on correction of gamma nonlinearity

In the fringe projection three-dimensional (3D) shape measurement, the gamma nonlinearity of the digital projector leads to measurement errors, a novel method based on the dual-frequency fringe projection using correction of gamma nonlinearity is proposed. In the proposed method, the pre-coded gamma values of computer generated fringe patterns in digital projector can guarantee the sinusoidal waveforms of the captured fringe pattern, and alleviate the measurement errors caused by the gamma nonlinearity. After the correction of gamma nonlinearity, the shape measurement results by dual-frequency grating projection are analyzed in detail. By combining the advantages of both low frequency and high frequency gratings, the object surface profile is obtained accurately. The simulation and experiment results are presented to validate the proposed method.