基于多频外差的相位误差校正方法

Phase-Error Correction Based on Multifrequency Heterodyning

  • 摘要: 在多频外差结构光三维测量技术中,相位误差严重影响了测量的准确性。针对这一问题,本文提出了一种基于多频外差的相位误差校正方法。首先对投影设备进行非线性校正,使用多项式逆向推导输出光强和输入光强关系,利用该多项式对输入相移条纹图像进行反演校正;并提出高斯自适应双边滤波算法,用于对相机拍摄的相移条纹图像进行去噪处理;随后对处理后的图像使用相移法生成截断相位,通过优化正向构造连续辅助相位和逆向推导截断相位级数约束过程进行绝对相位恢复。实验结果表明,校正后的非线性平均绝对误差和均方根误差分别减少了74.58%和77.65%,有效降低了绝对相位的非线性误差。此外,所提方法对相位跳跃性误差的抑制效果明显,得到的点云模型表面更加平滑,且在测量标准块阶梯高度差时,绝对误差和相对误差分别降至0.034 mm和0.38%,提升了结构光三维测量系统的测量精度和鲁棒性。

     

    Abstract: In multifrequency heterodyne-structured light three-dimensional measurement technology, phase errors significantly affect the measurement accuracy. Hence, this paper proposes a phase-error correction method based on multifrequency heterodyne. First, a nonlinear correction was performed on the projection device using a polynomial to deduce the relationship between the intensities of the output and input lights. Subsequently, this polynomial was used to correct the input phase-shifted fringe pattern. A Gaussian adaptive bilateral filtering algorithm was proposed for denoising the phase-shifted fringe pattern captured by the camera, and the processed images were used to generate a truncated phase using the phase-shifting method. Absolute phase recovery was performed by optimizing the forward construction of the continuous auxiliary phase and the inverse derivation of the truncated phase-series constraint process. Experimental results show that, after correction, the nonlinear average absolute error and root mean square error were reduced by 74.58% and 77.65%, respectively, thereby effectively reducing the nonlinear error of the absolute phase. Additionally, the proposed method effectively suppressed the phase-jump error, thus resulting in a smoother surface for the point-cloud model. When measuring the step height difference of the standard block, the absolute error and relative error were reduced to 0.034 mm and 0.38%, respectively, thus enhancing the measurement accuracy and robustness of the structured light three-dimensional measurement system.

     

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