一种基于重投影和3D-DIC的曲面变形测量方法

A surface deformation measurement method based on reprojection and 3D-DIC

传统双目立体视觉测量基于立体校正进行三维重建,测量精度受标定参数精度、插值精度以及双目传感器结构的影响很大。在进行曲面尤其是大曲率ROI变形测量时,立体校正过程会导致立体图像对中不均匀变形信息的损失或者过度拟合,进而影响测量精度。为此,本文发展了一种基于重投影和3D-DIC,适用于曲面变形测量的无需立体校正或外极几何约束校正的高精度立体匹配方法。同时,这种方法也可推广用于含有不均匀变形的时序图像对的高精度匹配。具体地,本文提出了二阶变形参数初值估计方法,二阶变形参数初值生长匹配策略,全局立体匹配和时序匹配策略;进一步,给出了不依赖于立体校正和极线校正的特征点三维重建方法,全局变形场及局部应变场的计算方法。实验证明本文所提方法可实现一定曲率曲面的高精度变形测量,测量系统在一定景深内能够实现小于1μm的平均测量误差。

The traditional binocular stereo vision measurement is based on stereo rectification for 3D reconstruction.The measurement accuracy is greatly influenced by the calibration parameter accuracy,interpolation accuracy and binocular sensor structure.When measuring the deformation of surface,especially large curvature ROI,the stereo rectification process could cause the loss or over-fitting of the non-uniform deformation information in the stereoscopic image pairs,which further affects the measurement accuracy.To address this issue,a high-precision stereo matching method is proposed based on reprojection and 3D-DIC,which is suitable for surface deformation measurement without stereo rectification or epi-polar geometric constraint correction.Meanwhile,this method can also be extended to high-precision matching of time series image pairs containing non-uniform deformation.Specifically,this article proposes the estimation method of second-order deformation parameters,the growth matching strategy of second-order deformation parameters,and the global stereo matching strategy and the time series matching strategy.Furthermore,the 3D reconstruction method of feature points independent of stereo rectification and epi-polar correction,and the calculation method of global deformation field and local strain field are given.Experiments show that proposed method can achieve high precision deformation measurement of a curved surface,and the measuring system can achieve an average measurement error of less than 1μm in a certain depth of field.