Discriminating large lattice rotations from strain
In the situation where the measured lattice rotations are large then infinitesimal strain theory does not apply. Remapping is a procedure introduced to remove large rotations so that infinitesimal strain theory can be once again used to measure elastic strain values.
In the remapping procedure the initially measured rotation is used to back rotate each pixel within each ROI to present the EBSD pattern without the rotation. A second XCF pass is then performed to obtain the improved measure of the strain tensor. In practice the remapping is performed at the subpixel level effectively taking into account the change in pixel shape produced by the rotation. It is necessary to apply remapping for primary measured rotations greater than 1 degree.
1st pass XCF processing strain results 2nd pass Remapped strain results
Fig 1. E11 Normal Strain Sample Axis
HR EBSD measurements of a single grain of Titanium showing how Remapping removes the interference of lattice rotations in strain measurements