Fringe projection profilometry (FPP) has been extensively used to measure three-dimensional (3D) shape in recent years. Generally, high-frequency fringe patterns ensure high accuracy, while fewer patterns mean higher measuring speed in FPP. However, simultaneously meeting the high-frequency and few-patterns without any constraints are still big challenges, because several additional unwrapping patterns are needed to unwrap the high-frequency patterns. We propose a novel high-accuracy high-speed unconstrained method to obtain the 3D shape by projecting only four fringe patterns. The period of the fringe patterns in the proposed method reaches 70. The high frequency ensures the high measuring accuracy. Besides, only one additional pattern is used to unwrap the high-frequency patterns, ensuring the high measuring speed. This method calculates the absolute phase pixel by pixel independently without any pre-work or constraints, which is suitable for complex and isolated objects. The experimental results verify the high-speed and high-accuracy performance of our method.

近年来，条纹投影轮廓仪（FPP）已被广泛用于测量三维（3D）形状。通常，高频条纹图案可确保高精度，而更少的图案意味着FPP中的测量速度更高。然而，同时满足高频和少量模式而没有任何限制仍然是很大的挑战，因为需要几个附加的展开模式来展开高频模式。我们提出了一种新颖的高精度高速无约束方法，通过仅投影四个条纹图案来获得3D形状。所提出的方法中条纹图案的周期达到70。高频确保了高测量精度。此外，仅使用一种附加图案即可解开高频图案，从而确保高测量速度。该方法可以独立地逐像素计算绝对相位，而无需任何前功或约束，适用于复杂且孤立的对象。实验结果证明了我们方法的高速和高精度性能。