阵列式高空间分辨率三维数字图像相关方法研究

In recent years, as a non-contact, three-dimensional and full-field deformation measurement technique, three-dimensional (3D) digital image correlation (DIC) has been widely used in both scientific and engineering fields. With the deepening of research on applications of DIC, researchers have raised higher requirements on the spatial resolution of deformation measurement, such as deformation measurement of rock, concrete and weld. To improve the spatial resolution of DIC measurements, during the doctoral period of the applicant, relevant research has been carried out. The two-dimensional (2D) camera array technique and sub-pixel image stitching technique were combined to improve the spatial resolution of imaging, so the spatial resolution of 2D deformation field can be improved. However, the 2D camera array can only be used to measure in-plane deformation of planar objects, so it is unable to meet the urgent needs of 3D deformation measurement. Meanwhile, due to the arbitrariness of the stereo camera pair, the calibration method, reconstruction method and deformation analysis method of 3D camera array are quite different with 2D camera array, these issues are subject to further research. The establishment of 3D camera array method will help to improve the spatial resolution of 3D deformation measurement greatly. This project is engaged in the research of camera array-based high-spatial resolution 3D digital image correlation method, to provide a high-resolution, non-contact, 3D and full-filed deformation measurement method for research on the deformation and failure mechanism of materials and the mechanical behavior of structures under complex conditions.

近年来，作为非接触式三维全场变形测量技术，三维数字图像相关被广泛应用于科研和工程领域。随着数字图像相关应用研究的不断深入，研究人员对变形测量的空间分辨率提出了更高要求，如岩石、混凝土、焊缝的变形测量等。为了提高数字图像相关变形测量的空间分辨率，申请人博士期间开展了相关研究，通过二维相机阵列和亚像素图像合成技术来提高成像分辨率，进而提高二维变形场测量的空间分辨率。但是，二维相机阵列只能用于平面物体的面内变形测量，无法满足三维变形测量的迫切需求。同时，由于三维相机阵列中立体相机对组合的任意性，其标定方法、重构方法和变形解析方法都与二维相机阵列有很大的不同，这些问题都有待于进一步研究。三维相机阵列方法的建立将会大大提高三维变形测量的空间分辨率。本项目拟从事阵列式高空间分辨率三维数字图像相关方法研究，为复杂条件下材料的变形与破坏机理及结构的力学行为研究提供一种高分辨、非接触、三维全场变形测量手段。

物体表面变形场测量是分析材料力学参数、研究结构力学性能、认知力学行为、探索自然奥秘的直接手段。变形测量空间分辨率的提高，将进一步拓宽测量技术的应用范围，为复杂条件下材料和变形与破坏机理及结构的力学行为研究提供更为有效的测量手段。本研究针对三维数字图像相关方法变形测量空间分辨率的提高，提出阵列式高空间分辨率变形测量方法，研制了三维相机阵列测量变形测量仪器，最终实现了项目的研究目标。同时，针对三维相机阵列中的技术问题，提出并实现了一种基于编码标定法的阵列相机标定与拼接方法；提出并实现了一种基于变形传递的大变形和选择的实时三维数字图像相关方法；提出并实现了三维相机阵列数据融合方法和变形解析方法。在基于方法研究的基础上，将所提出三维相机阵列测量技术在混凝土断裂参数测量和电子芯片热翘曲变形测量中进行了应用。在混凝土断裂参数测量中，基于测量得到的高分辨率位移场与虚主应变场，理论分析了虚主应变场和裂纹张开位移的关系，通过激光条纹中心线识别的Steger算法，实现了裂纹中心线的提取和裂纹宽度的高精度测量，裂缝宽度识别精度可达0.02像素。在电子芯片热翘曲变形测量中，实现了600mm×600mm视场下面内位移1微米、离面位移2微米的高分辨测量，指标超过国际同类设备。