Development of 3-D Digital Image Correlation Using a Single Color-Camera and Diffractive Speckle Projection

A method for performing three-dimensional (3-D) Digital Image Correlation (DIC) using a single color-camera is described. The method takes advantage of the three independent Red-Green-Blue (RGB) color signals available on a color-camera sensor to gain 3-D displacement information. Conventional two-dimensional (2-D) DIC of an applied surface pattern is recorded using the pixels of one color to obtain in-plane surface displacements. Out-of-plane displacements are measured using telecentric speckle projection, illuminated in a second color. Separate 2-D DIC measurements of the two color pattern images provide full-field 3-D displacement measurements. This approach significantly reduces the spatial computations compared to conventional dual-camera 3-D DIC. This single color-camera method is expanded upon to enable the technique to measure 3-D displacements of non-planar specimens. The technique provides sufficient additional information to enable independent measurement and correction of camera perspective errors. Results of rigid body displacements for a planar and cylindrical surface are presented as well as a complex 3-D deformation of a rubber sample.