【摘要】 为了减少所需投影的条纹帧数，希尔伯特变换已经被运用于基于条纹投影的三维测量技术中。然而对于非平滑反射率信号，基于希尔伯特变换的计算将会引入较大的相位误差，从而影响相位展开的准确性。文中提出了一种面向非均匀反射率彩色物体四帧双频条纹投影的相位提取方法，通过将非连续的正弦信号转换成纯交流分量，从而巧妙避免了反射率带来的影响。该算法将前三帧高频图样用来计算高频包裹相位和背景直流分量；将一帧低频图样分别减去和除以直流分量后来提取纯交流分量。基于希尔伯特变换，低频包裹相位被准确计算，从而在几何约束方法的辅助下展开低频相位。最后采用双频方法展开高频相位，从而获取物体的三维形貌。实验结果验证了所提方法在非平滑反射率的彩色物体上的有效性，扩展了传统方法的适用范围。更多还原

【Abstract】 To reduce the number of required projected stripe frames, the Hilbert transform has been employed in fringe projection-based three-dimensional(3D) measurement techniques.However, for non-smooth reflectivity signals, the Hilbert transform will introduce large phase errors, which will affect the accuracy of phase unwrapping.In this paper, a phase extraction method for four-frame dual-frequency fringe projection of color objects with non-uniform reflectivity was proposed, and it avoided the effect of reflectivity by converting a non-continuous sinusoidal signal into a pure AC signal.The first three frames of the high-frequency patterns were used to calculate the high-frequency wrapped phase and the background DC component.And meanwhile, one frame of the low-frequency pattern was respectively subtracted and divided by the DC component to extract the pure AC low-frequency component.Based on the Hilbert transform, the low-frequency wrapped phase was calculated accurately, and thus the low-frequency phase was unwrapped with the aid of the geometrical constraint method.Finally, the high-frequency phase was unwrapped by the dual-frequency method to obtain the 3D shape of the measured object.The experimental results verified the effectiveness of the proposed method on colored objects with non-smooth reflectance, expanding the applicability of the conventional method.更多还原