光栅投影三维测量系统标定技术研究

Study on calibration method of grating projection 3D measuring system

  • 摘要: 相机与投影仪的标定是影响光栅投影三维测量系统精度的因素之一,且标定所得参数的精度直接影响系统的测量精度。分析标志点边缘成像时的退化模型,提出了基于高斯曲线拟合与边缘局部区域效应相结合的亚像素边缘检测方法,获取高精度边缘,提高标志点检测精度;使用基于透视变换图像矫正的标志点快速排序匹配方法,进行相机快速高精度标定。分析投影仪标定时的相位误差,提出了一种基于径向基的线性插值方式,提高标志点圆心相位获取精度。实验验证,使用上述亚像素边缘检测方式,标志点的边缘残差为0.0871,对比基于高斯曲线的拟合方式,精度提高了41%,相机标定重投影误差均值为0.0524像素;使用上述相位插值方式,投影仪标定重投影误差均值为0.1203像素,对比使用双线性插值方式,标定精度提高23.9%。

     

    Abstract: The calibration of both camera and projector becomes the key element to decide the accuracy of 3D fringe projection measurement, and accuracy of parameter calibration directly affects accuracy of the measurement. By analyzing the imaging degradation model of mark points, a sub-pixel edge detection method was proposed to obtain the high-precision edges based on the combination of Gaussian curve fitting and edge partial area effect, and thus to improve the accuracy of mark point detection. A quick sort matching method of mark points was presented based on the image rectification technic by way of perspective transformation, and the high-precision camera calibration was finished rapidly. Furthermore, by analyzing the phase error in projector calibration, a linear interpolation method was proposed based on radial basis function in order to improve the phase accuracy of circle center of mark points. Then the experimental results show that the edge residual error of mark points is 0.087 1. Compared to the Gaussian curve fitting method, its accuracy is improved by 41%, the average re-projection errors of camera calibration is 0.052 4 pixels, and the re-projection error of projector is 0.120 3 pixels. Compared to the bi-linear interpolation method, its calibration accuracy is increased by 23.9%.

     

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