基于正弦和三角波条纹投影的三维测量方法

Three-dimensional shape measurement method based on sinusoidal and triangular fringe projection

在现有的针对复杂物体表面形貌的三维测量方法中,为了完成绝对相位的测量,通常需要处理至少6幅条纹图像,限制了测量速度。提出了采用2幅正弦条纹和2幅三角波条纹图来获得物体三维形貌的方法。利用两步相移正弦条纹和两步相移三角条纹得到截断相位,再利用两步相移三角波条纹得到条纹级次,减少了投影条纹幅数,提高测量速度。在得到条纹级次时,计算三角波条纹强度调制和强度对比度,与计算相位相比,可以减少数据处理的时间,进一步提高测量速度,同时能减小物体表面反射率的影响,提高了测量精度。测量最大高度为39mm的阶梯状标准块,得到的最大绝对误差和最大的RMS误差分别为0.045mm和0.041mm。验证了该方法的有效性和实用性,在高速实时的复杂形貌三维测量中有广泛的应用前景。

In the existing three-dimensional measurement method for the surface topography of complex objects,in order to complete absolute phase measurement,it is usually necessary to process at least 6 fringe images,which limits the measurement speed.A method for obtaining three-dimensional shape of object by using two sinusoidal fringes and two triangle wave fringe patterns was proposed.The two-step phase-shifting sinusoidal fringe and two-step phase-shifting triangular wave fringe were calculated to obtain the wrapped phase,then the two-step phaseshifting triangular wave fringe was used to determine fringe order.Due to the decrease in number of projection images,the speed of measurement increased.In order to obtain the fringe order,the triangular wave fringe intensity modulation and intensity ratio were calculated.Compared with the calculation of the phase,the data processing time can be reduced,and the measurement speed can be further increased.At the same time,the influence on the surface reflectance can be reduced,and the measurement accuracy can be improved.For measuring the stepped standard block with maximum height of 39 mm,the maximum absolute error and the maximum root-mean-square（RMS）error are 0.045 mm and 0.041 mm,respectively.Experimental results demonstrate that the proposed method is effective and practical,the benefits are seen in the highspeed,real-time 3-D shape measurement of complex objects.