Efficient 3-D Measurement Based on De Bruijn Nonuniform Periodic Phase-Shifting

The fringe projection profilometry (FPP) has become a research hotspot both domestically and internationally in recent years due to its high precision and noncontact nature. However, reconciling measurement efficiency and accuracy has remained a challenging issue in FPP. Therefore, this article proposes a 3-D measurement method based on De Bruijn nonuniform phase shifting (DBNU-PS), which is efficient and highly accurate without the need for any additional patterns. In the encoding phase, multiple single-frequency fringes with different frequencies are combined according to the De Bruijn (DB) sequence to generate a set of nonuniform phase-shifted fringes. In the decoding phase, the approximate phase obtained from phase gradient is locally unwrapped, and the phase order is calculated by minimizing the nonlinear error on the mapped phase to achieve unambiguous phase unwrapping. Additionally, the proposed method does not require additional equipment, ensuring low-cost measurements. Experimental results demonstrate that the proposed method achieves measurement accuracy equivalent to multifrequency (MF) phase-shifting (PS) with only 1/3 of the projection patterns. This method provides a promising solution for improving the efficiency of high-speed 3-D measurements.