EBSD Spherical Indexing

EBSD Spherical Indexing [released along with EMsoft 5.0]

Please note that an extensive tutorial for dictionary indexing can be obtained in the Complete Examples section (item 7) of this wiki collection. Except for the very last step, Spherical Indexing and Dictionary Indexing use the same workflow.

Spherical Indexing, or SphInx for short, is a new technique for diffraction pattern indexing that employs the complete pattern instead of extracting features from the pattern. In the traditional Hough-based indexing for EBSD patterns, individual Kikuchi band orientations and locations are extracted from the pattern and then processed to extract interplanar or interzonal angles that are then compared against a lookup table. In the SphInx approach, no feature extraction is performed and complete patterns are compared to simulated patterns; hence the need for a good forward model to predict patterns.

The complete algorithm description for spherical indexing can be found in W.C. Lenthe, S. Singh, and M. De Graef. "A Spherical Harmonic Transform Approach to the Indexing of Electron Back-Scattered Diffraction Patterns". Ultramicroscopy 207, 112841 (2019).

The indexing programs are not part of EMsoft; instead, they are available in 0.9 beta form from aseparate repository and they are GPL licensed (as opposed to EMsoft which has a BSD3 license).