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为实现动态物体的实时三维测量,提出了一种基于经验模式分解的三频彩色条纹投影轮廓术。将低、中、高三种频率的正弦条纹分别经投影仪红(R),绿(G),蓝(B)通道同时投影至被测物面,CCD在另一角度拍摄变形条纹图。将变形条纹图R、G、B三分量互减消减背景干扰,用经验模式分解进行颜色解耦,分离各载频项,进而以傅里叶变换解调相位。以变精度去包裹算法按低、中、高频依次完成包裹相位展开,得到高频载频项的展开相位。计算机模拟时相位解调的标准差小于0.0417rad,具有较高的测量精度;对比实验和面部表情变化实验进一步说明了方法的可靠性。该方法在单次拍摄下实现了相位的解调及高精度相位的精确展开,为动态物体的高精度轮廓测量提供了有效的手段。
In order to realize real-time three-dimensional measurement of dynamic objects, a tri-color color fringe projection profilometry based on empirical mode decomposition was proposed. Sine fringes of low, middle and high frequencies will be projected onto the measured object surface through the red (R), green (G) and blue (B) channels of the projector at the same time, and the CCD will shoot the deformed fringe pattern at another angle. Degenerate fringe patterns R, G, B three-component subtraction of background interference reduction, empirical mode decomposition for color decoupling, the carrier frequency separation, and then Fourier transform phase demodulation. The variable-precision unwrapping algorithm completes the phase unwrapping of the package according to the low, medium and high frequency to obtain the unwrapping phase of the high frequency carrier frequency term. The standard deviation of the phase demodulation in computer simulation is less than 0.0417rad, which has higher measurement accuracy. The experiment of contrast and facial expression variation further demonstrate the reliability of the method. The method realizes phase demodulation and precise phase unwrapping under a single shot, which provides an effective method for high-precision contour measurement of dynamic objects.