Importing EBSD data collected from Oxford AZtec

[Ryann Rupp]

Hi, 

I am having some difficulty understanding how to properly import EBSD data collected from Oxford Aztec using MTEX's import wizard. I have been reading the help files regarding the ctf interface flag and issues with absolute orientations, but I still cannot figure out which is option is correct. I have been trying to follow the advice of checking the ipf maps with those produced by AZtec AND checking that the points on the corners have the correct map orientation and Euler angles. However none of the options on the import wizard appear to meet these criteria. 

For example, I have a scan that is 598 um x 318 um. From the .ctf file, I know these points have the following Euler angles.

Spatial Coordinates/ Euler Angles

(0,0)/(341.78, 35.626, 37.988)

(598,0)/(176.58, 46.554, 37.926)

(0,318)/(187.61, 52.273, 48.084)

(598, 318)/ (46.072, 49.463, 48.641)

When using the 'convertEuler2SpatialReferenceFrame'

(0,0)/(198, 144, 218)

(598, 0)/ (3, 133, 218)

(0, 318)/ (352, 128, 228)

(598,318)/ (134, 131, 229)

Selecting this option flips the ipf in the y direction compared to the ipf produced by AZtec. The Euler angles in MTEX also are obviously not identical to the .ctf file. The spatial coordinates do match. 

When using the 'convertSpatial2EulerReferenceFrame'

(0,0)/(342, 36, 38)

(598,0)/(177, 47, 38)

(0,-318)/(188, 52, 48)

(598, -318)/ (46, 49, 49)

Selecting this option creates the same ipf as the one produced by AZtec. The Euler match the .ctf file but now the spatial coordinates do not. The spatial coordinates seem to take the form (x, -y).

Can anyone please help me figure out what is the correct way to import my EBSD data? Are either of these options better than the other or is there an even better option I am not aware of to import my data? I believe this is probably related to the fact that the origin for the EBSD data collected using AZtec begins in the top left corner and works its way down (similar to reading a book).

Thank you for your time. I really appreciate the help.

Sincerely, 

Ryann  

[Rüdiger Kilian]

Hi Ryann,
the issue is that in many ebsd systems, the coordinate system of the map and the one of the euler angles may not be identical, for example, one some (many?) Aztec systems the map is displayed in beamview (and the top edge is the deepest point in the chamber) but the orientations (and polefigures and ipf colors) are displayed with respect to the camera view (so what you see in Aztec - unless it's fixed by now, I don't know - is not correct);  in in that case one would have to rotate either the map or the orientations by 180* in Aztec to be correct and that's how they should then also be in mtex if you picked the correct import options. Also note that some versions of Channel5 Aztec offered to specify the coordinate system  when exporting ctf (does not apply for crc) which turned out to not work properly for some versions of that software. I also cannot confirm if it does something by now.
I personally wouldn't rely on the manual of the manufacturer but do one of the tests (a) either use a benchmark sample with a known orientation with preferentially is oriented in a way to be able to detect any rotations or (b) do on of the rotation or tilt tests that have been suggested here (and also on the geotectonics mailing list, some moment in January 2016, and I guess there's a paper https://doi.org/10.1016/j.matchar.2016.04.008).

Cheers,
Rüdiger

[David Mainprice]

Typically for importing using MTEX Import wizard Below see Specimen Reference Frame options.

The use CTF interface flag ‘convertEuler2SpatialReferenceFrame'

The X-Y-Z convention will depend on your SEM setup - in the example the x-axis is parallel to x-axis and z-axis to normal to specimen surface

One of 8 options should work for you.

all the best David

 

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[Rüdiger Kilian]

I guess that could be a working link, sorry:
https://doi.org/10.1016/j.matchar.2016.04.008
http://www.sciencedirect.com/science/article/pii/S1044580316300924