基于光栅投影测量改进的类双目系统标定方法

Revised system calibration method of analogy binocular based on fringe projection profilometry

  • 摘要: 系统标定是光栅投影测量系统中的关键一步。将投影仪看成相机的类双目系统标定方法具有操作简单、精度高、可靠性强的优势。在此系统标定方法的基础上,提出一种提高测量系统精度的系统标定方法。根据提取的标定板上圆标识的圆心坐标,利用计算机生成含有相对应十字标识的图像,用于相机标定,可避免圆标识轮廓对角点提取的影响,从而提高相机标定精度。同时,推导快速求取投影仪伽马的表达式用于相位校正,可建立投影仪像素与相机像素精确的对应关系,从而提高投影仪标定精度。结合投影仪和相机的标定结果,建立统一的世界坐标系完成整体系统的标定。实验结果表明:采用上述标定方法,可将投影仪和相机标定精度分别达到0.25 pixel和0.15 pixel;同时测量了一个长方体,精度达到0.142 7 mm。

     

    Abstract: System calibration is a key procedure in fringe projection profilometry. The system calibration method of analogy binocular which regards projector as camera has the advantages of simple operation, high precision and high flexibility. Based on this method, a calibration method for accuracy enhancement of measurement system was presented. According to the extracted center coordinates of circle marks onto calibration board, the images for camera calibration which included the corresponding cross marks, were generated by a computer to avoid the influence of circle mark profile on corner extraction and improve camera calibration accuracy. In the meanwhile, the theoretical expression of fast calculating projector Gamma for phase correction was derived. Then pixel-to-pixel mapping between projector and camera can be accurately set up for projector calibration accuracy enhancement. Combined with the calibration results of projector and camera, it need establish unified world coordinate system for system calibration. The experiment results show by using the above calibration method, the calibration precisions of projector and camera can achieve 0.25 and 0.15 pixel, respectively, and the precision of a cuboid block measured can achieve 0.142 7 mm at the same time.

     

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