Time slicing, an image processing technique to visualize the temporal development of fabrics

Thinking of a sequence of images (or of frames of a film) as a three-dimensional x-y-t stack with two length dimensions (x, y) parallel to the image plane and one time dimension (t) perpendicular to it, we propose to cut this stack parallel to the time axis, thus producing so-called time slices. On these time slices, the horizontal dimension is length: a straight line parallel to any direction in the x-y plane of the images. The vertical dimension is time. The one-dimensional movements of particles parallel to the plane of section can be observed as straight or curved time traces, depending on whether the displacement rates of the particles are constant or variable. onstrate practical applications of this idea, we use three sets of images that were recorded in the course of see-through simple shear experiments on norcamphor: two stacks of polarization images and one stack consisting of c-axis orientation images. The stacks were cut parallel to the shear zone boundary. Techniques for the acquisition of the original image sequences, the steps of digital image preprocessing and the preparation of the time slices (x-t images) are described in detail. Problems associated with the temporal calibration, the derivation of true bulk strain and bulk strain rates, and the distinction of artefacts receive special attention. The influences of strain localization and grain boundary migration are discussed. On time slices of orientation images, the spatial evolution of texture domains, passive lattice rotation and lattice reorientations associated with nucelation can be distinguished.