分区域Gamma预编码校正的相位误差补偿

Subregional Gamma Pre-coding Correction for Phase Error Compensation

针对现有结构光视觉测量中普通投影仪亮度不均匀引起系统Gamma非线性畸变值分布差异,从而导致相位误差问题,提出了一种自适应分区域Gamma预编码校正方法。首先,介绍了结构光双目视觉测量原理以及标准N步相移法。接着,分析了投影仪和相机的Gamma非线性畸变对光栅正弦性的影响以及预编码校正方法。然后,在获取Gamma值分布规律的基础上,根据Gamma值的变化与相位误差的关系确定分区域阈值大小。最后,根据确定的阈值对测量视场进行区域划分,获取各区域Gamma值,并对标准白板和汽车挡泥板进行了实际测量。实验结果表明:本文方法比相同条件下采用单一Gamma值预编码校正方法在相位误差的补偿精度上提高了约30%,在三维数据的测量精度上提高了约15%。该方法能更好地减小相位误差,提高结构光视觉测量系统的精度。

In structured light vision measurement, since non-uniformity of brightness of the common projector caused nonlinear distortion Gamma value distribution difference resulting in phase error problem, a self-adaptive subregional Gamma value pre-coding correction method was proposed. First, the principle of structured light stereo vision measurement and standardN step phase shifting method is introduced. Second, the projector and the camera＆#39;s nonlinear distortion of sine grating and the Gamma value pre-coding correction method are analyzed. Then, on the basis of Gamma value distribution, according to the relationship between the change of Gamma value and the phase error, subregional threshold was calculated. Finally, according to the threshold, the measurement field was divided and subregional Gamma pre-coding correction method was implemented, and actual measurement was carried out on a standard white plate and a fender. Experimental results indicate, under the same conditions, compared with single Gamma pre-coding correction method, the proposed method can further improve phase error compensation about 30%, and the measurement accuracy increase by about 15% in the 3D data.