Zhu Sijie, Cao Yiping, Zhang Qican, Wang Yajun
Opt Express. 2022 Sep 26;30(20):35539-35553. doi: 10.1364/OE.472642.
By utilizing 1-bit binary fringe patterns instead of conventional 8-bit sinusoidal patterns, binary defocusing techniques have been successfully applied for high-speed 3D shape measurement. However, simultaneously achieving high accuracy and high speed remains challenging. To overcome this limitation, we propose a high-efficiency and robust binary fringe optimization method for superfast 3D shape measurement, which consists of 1D optimization and 2D modulation. Specifically, for 1D optimization, the three-level OPWM technique is introduced for high-order harmonics elimination, and an optimization framework is presented for generating the 'best' three-level OPWM pattern especially for large fringe periods. For 2D modulation, a single-pattern three-level OPWM strategy is proposed by utilizing all the dimensions for intensity modulation to decrease the required projection patterns. Thus, the proposed method essentially belongs to the 2D modulation technique, yet iterative optimization is carried out along one dimension, which drastically improves the computational efficiency while ensuring high accuracy. With only one set of optimized patterns, both simulations and experiments demonstrate that high-quality phase maps can be consistently generated for a wide range of fringe periods (e.g., from 18 to 1140 pixels) and different amounts of defocusing, and it can achieve superfast and high-accuracy 3D shape measurement.
通过使用1位二进制条纹图案而非传统的8位正弦图案，二进制散焦技术已成功应用于高速三维形状测量。然而，同时实现高精度和高速度仍然具有挑战性。为克服这一限制，我们提出了一种用于超快速三维形状测量的高效且稳健的二进制条纹优化方法，该方法由一维优化和二维调制组成。具体而言，对于一维优化，引入了三电平OPWM技术以消除高次谐波，并提出了一个优化框架来生成特别是对于大条纹周期的“最佳”三电平OPWM图案。对于二维调制，提出了一种单图案三电平OPWM策略，通过利用所有维度进行强度调制以减少所需的投影图案。因此，所提出的方法本质上属于二维调制技术，但沿一个维度进行迭代优化，这在确保高精度的同时极大地提高了计算效率。仅使用一组优化图案，仿真和实验均表明，对于广泛的条纹周期（例如，从18到1140像素）和不同程度的散焦，均可一致地生成高质量的相位图，并且它可以实现超快速和高精度的三维形状测量。
