基于双目结构光的肝脏表面三维重建系统标定研究

Calibration of 3D reconstruction system for liver surface based on binocular structured light

针对术中结构光肝脏表面三维重建存在标定难的问题,本文提出了一种针对肝脏表面三维重建系统的高精度标定方法。对手术过程中肝脏三维重建系统的双目模型和手术视场进行分析,确定双目相机和投影仪摆放的位姿。对双目相机之间的位姿转换进行分析,并完成其标定。同时提出基于三频四步解相法的投影仪标定方法,进而从三频四步解相原理出发,制定解相流程。对投影仪标定过程中存在的标定板质心求解困难的问题,提出了基于亚像素坐标线性插值的椭圆质心求解方法。根据实际的手术需求,选择合适的硬件,搭建了肝脏表面三维重建系统的实验平台。在此基础上通过多组标定实验,获得的系统的平均标定误差为0.078 mm,最大标定误差为0.099 mm。本文提出的肝脏三维重建系统的标定方法具有较高的标定精度,符合医生手术过程中的实际需求。

To address the difficulty of liver surface 3 D reconstruction system based on structured light during operation, this paper proposes a high-precision calibration method for liver surface 3 D reconstruction system. First, the binocular model and surgical field of view of the 3 D reconstruction system of the liver during the operation are analyzed, and the positions of the binocular camera and the projector are determined. Then, the pose conversion between binocular cameras is analyzed, and its calibration is completed. A projector calibration method based on the three-frequency and four-step phase solution method is proposed, and the phase solution process is formulated based on the principle of three-frequency and four-step phase solution. To address the difficulty of solving the centroid of the calibration plate in the process of projector calibration, an elliptic centroid solving method based on linear interpolation of subpixel coordinates is proposed. Finally, according to the actual surgical requirements, the appropriate hardware is selected to build an experimental platform for the three-dimensional reconstruction system of the liver surface. On this basis, several groups of calibration experiments indicate that the average calibration error of the system is 0.078 mm, and the maximum calibration error is 0.099 mm. Therefore, the proposed calibration method of the 3 D liver reconstruction system has high calibration accuracy and meets the actual needs of doctors during the operation process.