用于高反表面测量的分块平滑自适应条纹投影方法  

Block-smoothed adaptive fringe

作　　者：何信欣 刘斌[1,2] 王春柳[1] 吴冠豪 He Xinxin;Liu Bin;Wang Chunliu;Wu Guanhao(Tianjin Key Laboratory for Control Theory&Applications in Complicated Systems,School of Electrical Engineering and Automation,Tianjin University of Technology,Tianjin 300384,China;State Key Laboratory of Precision Measurement Technology and Instruments,Department of Precision Instruments,Tsinghua University,Beijing 100084,China)

机构地区：[1]天津理工大学电气工程与自动化学院天津市复杂系统控制理论及应用重点实验室,天津300384 [2]清华大学精密仪器系精密测试技术及仪器国家重点实验室,北京100084

出　　处：《红外与激光工程》2023年第5期316-329,共14页Infrared and Laser Engineering

基　　金：国家自然科学基金(51835007);天津市自然科学基金(21JCZDJC00760),(21JCQNJC00910);天津市“项目+团队”重点培养专项(XC202054)。

摘　　要：条纹投影轮廓术用于测量高反表面时,相机成像会出现饱和区域,区域内相位信息难以提取,进而造成三维重建错误。为此,文中提出了一种分块平滑自适应条纹投影方法。首先,通过投影少量均匀灰度图,对饱和区域进行分块,根据各块的饱和程度,计算相应的初始投影强度。随后,在不饱和情况下,投射亮暗两种强度的条纹图,通过在饱和区域融合两者相位信息,实现相机到投影仪的坐标匹配,获取初始映射投影强度;然后,对初始映射投影强度进行多项式拟合,构建平滑的投影强度曲线,用于逐像素获取最佳投影强度值,同步填补了因相机与投影机分辨率差异引起的映射孔洞,最终生成自适应条纹。最后,将生成的自适应条纹投射至被测物体,进行了相位解算和三维重建。实验结果表明:所提方法只需投影少量灰度图就能生成高动态范围的自适应条纹,实现了饱和区域相位信息的完整提取。相比于现有改进方法,面形三维重建的标准偏差分别减少了40%和28.6%,有效地提高了高反表面形貌测量精度。Objective Fringe projection profilometry(FPP)has been established in a wide range of industrial applications.Its key advantages include high accuracy,fast speed,robustness,and non-contact operation.However,image saturation occurs inevitably in measuring high-reflective surface due to the light intensity exceeding the dynamic range of camera sensor.It leads to absolute phase errors and 3D reconstruction failures.It is not an effective approach to address this issue by roughly reducing the exposure time of the camera or shrinking the size of the lens aperture because the SNR of the fringe patterns would decrease.Therefore,measuring high-reflective surface is still a challenging task for conventional FPP.In this paper,we propose a block-smoothed adaptive fringe projection method for high-reflective surface measurement to achieve accurate 3D reconstruction.Methods Firstly,the saturated region is extracted and then divided into several blocks by projecting several uniform gray patterns.The initial projection intensity of each block is calculated according to the saturation degree.Secondly,the surface is illuminated by one set of bright fringe patterns and one set of dark ones in the unsaturated condition.The absolute phase map in the extracted saturated region is obtained by fusing the phase maps of the bright and dark fringe patterns.The coordinate mapping between the camera pixels and the projector units is carried out by the integrated phase map.And the initial mapping projection intensity on the projector is gathered.Thirdly,the polynomial function is fitted to the initial mapping projection intensity.The function is utilized to construct the smooth projection intensity curve.The optimal projection intensity of each saturated pixel is refined.And the mapping holes caused by the inconsistent resolution of the camera and projector are filled simultaneously.The adaptive fringe patterns are eventually generated.Finally,the adaptive fringe patterns are projected to the high-reflective surfaces to implement accurate pha

关 键 词：自适应条纹投影 三维测量 最佳投影强度 多项式拟合 孔洞填补 

分 类 号：O436[机械工程—光学工程]