  We reconstruct a 3D model of the surface of a material undergoing fatigue
testing and experiencing cracking. Specifically we reconstruct the surface
depth (out of plane intrusions and extrusions) and lateral (in-plane) motion
from multiple views of the sample at the end of the experiment, combined with a
reverse optical flow propagation backwards in time that utilizes interim single
view images. These measurements can be mapped to a material strain tensor which
helps to understand material life and predict failure. This approach offers an
alternative to the commonly used Digital Image Correlation (DIC) technique
which relies on tracking a speckle pattern applied to the material surface. DIC
only produces in-plane (2D) measurements whereas our approach is 3D and
non-invasive (requires no pattern being applied to the material).
