The indexing of EBSD patterns is a quite secret business. It is clear that the band detection is done by Hough or Radon transform. It is known that the indexing uses the angles between planes described by the extracted bands. It is somehow known as well that these angles are compared with a table of theoretically determined angles using the lattice parameters of the phase. It is also published how the voting scheme of TSL works, but how the indexing really works is nowhere described (as far as I know). Does it has been published somewhere, or does anybody knows it more precisely?
While there have been some improvements over the years, the core indexing algorithms used in our (EDAX-TSL) software have been pretty well documented:
• “Automatic Analysis of Electron Backscatter Diffraction Patterns” S.I. Wright and B.L. Adams. Metallurgical Transactions A 23, 759-767 (1992).
• “Advances in Automatic EBSP Single Orientation Measurements” K. Kunze, S.I. Wright, B.L. Adams and D.J. Dingley. Textures and Microstructures 20, 41-54 (1993).
• “Chapter 5 Fundamentals of Automated EBSD” S. I. Wright, in Electron Backscatter Diffraction in Materials Science, eds. A.J. Schwartz, M. Kumar and B.L. Adams, Kluwer Academic/Plenum Publishers: New York, 51-64 (2000).
As well as in my PhD thesis:
"Individual Lattice Orientation Measurements. Development and Application of a Fully Automatic Technique" Yale University (1992)
To my knowledge, the indexing algorithms used by other vendors have not been published but perhaps their software documentation provides some detail.
While there have been some improvements over the years, the core indexing algorithms used in our (EDAX-TSL) software have been pretty well documented:
• “Automatic Analysis of Electron Backscatter Diffraction Patterns” S.I. Wright and B.L. Adams. Metallurgical Transactions A 23, 759-767 (1992).
• “Advances in Automatic EBSP Single Orientation Measurements” K. Kunze, S.I. Wright, B.L. Adams and D.J. Dingley. Textures and Microstructures 20, 41-54 (1993).
• “Chapter 5 Fundamentals of Automated EBSD” S. I. Wright, in Electron Backscatter Diffraction in Materials Science, eds. A.J. Schwartz, M. Kumar and B.L. Adams, Kluwer Academic/Plenum Publishers: New York, 51-64 (2000).
As well as in my PhD thesis:
"Individual Lattice Orientation Measurements. Development and Application of a Fully Automatic Technique" Yale University (1992)
To my knowledge, the indexing algorithms used by other vendors have not been published but perhaps their software documentation provides some detail.
Hi Stuart, just now I could finally look through the literature you recommended and more than general and quite obvious equations (cross product) for the determination of plane normals derived from band positions I could not find. What I am missing is anything about the derivation of the normals from the Hough peak positions (rho,theta), which are the extracted information about the band positions, but also any detailed algorithms, how the indexing based on the correctly described plane normals really works, i.e. how the software finally matches the theoretical look-up-table angles with the experimental angles in order to identify one possible orientation. The evaluation of all solutions using the confidence index is clear.
Specifically, what I am looking for is, how I can determine an orientation by a set of (rho,theta) values, i.e. how the planes or their normal vectors can be derived. In the referred publications a band (line) is only described by two points P and Q but actually you do not have these points but only rho and theta so that there must be another description for the determination of the normal vectors n.
@ Rohan: The second paper only describes, how to determine the bands but does not tell anything about possible indexing algorithm. Nevertheless, many thanks.
As far as I remember there is only described how to detect bands but not how to index EBSD patterns.
As Stuart stated in his documents, I think EDAX use the 'Triplet Voting' to index the patterns and Oxford Instruments embraces a similar algorithm called "Class Indexing", which I found in their software brochure, it uses a group of 4 bands in the voting scheme instead of triplets.
I am also curious about the exact codes in their indexing algorithms, but maybe it's some kind of business confidentiality they don't want to make public, I have also search the patents but nothing was found.
Thanks Xin, therefore I was asking. The EDAX indexing is in principle described but only "in principle". The interesting part is actually missing (how it really works). But this is certainly confidential. Otherwise it would be written somewhere. The voting however is quite clear. From the other companies I don't know anything, only some rumors...
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