单周期条纹双四步相移投影仪的标定方法

针对投影仪标定方法中存在畸变及倾斜投影引起条纹周期、条纹级数变化的问题,提出一种单周期条纹双四步相移投影仪的标定方法.设计生成横向和纵向各两组单周期条纹图像,经投影仪投影到带有圆形标识的标定板上,相机同步采集标定板图像,叠加由双四步相移获得的两幅相位主值图,对叠加相位主值图相位展开,利用展开的绝对相位值计算投影仪像素坐标值,最终将投影仪标定转换为成熟的相机标定.实验结果表明:仿真投影仪标定实验准确度的最大重投影误差约为0.4pixel,均方根误差为0.132 96pixel;实际投影仪标定实验准确度的最大反投影误差约为0.46pixel,均方根误差为0.143 12pixel;实验结果与仿真结果的最大反投影误差相差15%,均方根误差相差7.6%.与现有的采用三频相位展开进行投影仪标定的方法相比,投影光栅图像数可减少8幅.该方法改善了现有投影仪标定方法的不足,标定准确度和标定效率均得到提高.

Projector Calibration Method with Single Period Fringe and Double Four-step Phase Shifting

Aiming at the projector distortion and the change of fringe periods and fringe series, a calibration method of single period fringe and double four-step phase-shifting algorithm was proposed.Designing and generating two groups of horizontal and vertical single period grating fringe images respectively, the camera captures the single period grating fringe images which projected onto the calibration plate with circular logo at the same time, and superposes the two phase master maps which obtained by double four-step phase shift and unwrapping the phase master map.Then the pixel coordinate of projector is calculated by the unwrapping absolute phase.Finally, the projector calibration is converted into a mature camera calibration.Experimental results indicate that the maximum re-projection error and the root mean square error of the projector calibration precision of simulation experiment are about 0.4 pixel and 0.132 96 pixel respectively.The maximum re-projection error and the root mean square error of the projector calibration precision of simulation experiment are about 0.46 pixel and 0.143 12 pixel respectively.Compared with the existing projector calibration methods of projecting fringes by tri-frequency phase unwrapping, 8 grating images can be reduced by the proposed method.The shortcomings of projector calibration method by projecting grating fringes and the calibration accuracy and the calibration efficiency can be improved.