Trouble Matching IPF Colors Between MTEX and DREAM.3D After Exporting Orientations

[WenxiLee]

Hello,

I have a trigonal-structured Al₂O₃ with the crystal symmetry defined as crystalSymmetry('-3m', [4.8, 4.8, 13.0], 'mineral', 'Al₂O₃') and space group 167.
I directly exported EBSD orientations (in radians) from MTEX to a CSV file.
However, when I load this CSV into DREAM.3D and generate the IPF color map with respect to the [001] direction, the colors do not match my MTEX results, and the image appears inverted.
I have attached my CSV file just in case.

Could you please give me some advice on this issue?
Do I need to apply some coordinate transformation or make other adjustments?

Thank you very much!
my_matrix_v2.csv

[imikejackson]

@WenxiLee

The "inversion" can be double checked by using DREAM3D-NX's visualization and displaying the Axes Grid option.

In that screen shot the Origin is located in the lower left hand corner and agrees with MTEX/MATLAB. When we write out the images ITK may be encoding the data to put the Origin in the Upper Left corner instead. And then your image viewer may be misinterperting the origin location that could potentially be store in the image file (Tiff images).

I am also including here the EBSD Legend for the Trigonal -3m Laue group from DREAM3D-NX. I would like to see the same legend from MTEX? That also might explain the coloring differences.

[WenxiLee]

Thank you for the quick reply and detailed explanation! I have copied the IPF convention here for reference, and I believe we are using the same convention.
I have also attached my data and MTEX file here(Zip). Actually, even when I directly load the .ctf file and calculate the IPF color in MTEX, the colors are still inconsistent with DREAM.3D. I do not think I need to apply an orientation transformation for this file, as it is already formatted similarly to HEDM data format
tmap-al2o3_data.zip
.

[imikejackson]

@WenxiLee

In the below image, the arrows point to an area that I cropped out and exported just the Euler Angles.

I then generated a polefigure for those data points. You can see a tiny black dot near the upper left area of the pole figure.

If we now look at where the corresponds to on the full IPF Legends considering the correct orientation of the labels,

you can see from the grey dots on each of the full IPF Legend colored pole figures, that the colors generated by both DREAM3D and MTEX agree with their respective legends.

The take away here is that you probably cannot compare IPF colors between different software packages but instead need to use the specific IPF Legends from each software package.

[WenxiLee]

Hi Michael,

Thanks for putting so much effort into comparing the results — it makes a lot more sense now. I feel confident moving forward!