Background

With the recent increase in digital image correlation (DIC) applications, it is important to improve the computational efficiency of DIC and realize the closed loop control of systems.

Objective

A real-time three-dimensional (3D) DIC method for large deformation and rotation measurements is proposed in this paper.

Methods

To solve the problem of initial guess estimation under large deformation and rotation, the convergence radius of the inverse compositional Gauss-Newton (IC-GN) algorithm considering large rotation and deformation is analyzed. Then, a temporal-spatial deformation transfer scheme is proposed for efficient temporal and stereo matching in 3D-DIC. The highly efficient IC-GN algorithm with an improved interpolation look-up table is proposed to further improve the computational efficiency. The multipoint and full-field real-time 3D deformation measurements are performed by parallel CPU computation.

Results

The convergence radius of IC-GN are estimated to be below 3 pixels for rotation and below 5 pixels for tensile deformation. The accuracy of the initial guess estimation by deformation transfer is improved and can meet the requirements of large deformation and rotation measurements. Benefiting from the temporal-spatial deformation transfer scheme, the efficient IC-GN algorithm, the efficient temporal and stereo matching strategy and the parallel computation, real-time multipoint deformation measurements at 60 Hz with 50 points and full-field deformation measurements at 15 Hz with 5000 points are realized.

Conclusions

Real-time multipoint and full-field 3D deformation measurements for large deformations and rotations are realized. High-accuracy, real-time and fully automatic 3D deformation measurement sensors are expected.

中文翻译：

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基于变形传递方案的大变形和旋转测量的实时3D数字图像相关

背景

随着近来数字图像相关性（DIC）应用的增加，重要的是提高DIC的计算效率并实现系统的闭环控制。

客观的

本文提出了一种用于大变形和旋转测量的实时三维（3D）DIC方法。

方法

为了解决大变形和大旋转情况下的初始猜测估计问题，分析了考虑大旋转和大变形的逆成分高斯-牛顿算法（IC-GN）的收敛半径。然后，提出了一种时空变形传递方案，以实现3D-DIC中的有效时空和立体匹配。提出了一种具有改进的插值查找表的高效IC-GN算法，以进一步提高计算效率。多点和全场实时3D变形测量是通过并行CPU计算执行的。

结果

估计IC-GN的会聚半径对于旋转而言小于3个像素，对于拉伸变形而言小于5个像素。通过变形传递进行初始猜测估计的准确性得以提高，并且可以满足大变形和旋转测量的要求。得益于时空变形传递方案，高效的IC-GN算法，高效的时空和立体声匹配策略以及并行计算，60 Hz的实时多点变形测量（50个点）和15 Hz的全场变形测量5000点的实现。

结论

实现了大变形和旋转的实时多点和全场3D变形测量。预计将需要高精度，实时和全自动的3D变形测量传感器。