Difference between Axis Euler Angles and Average Euler Angles

[Maliesha Kalutotage]

Hi,

I use both the "Find Feature Average Orientations" and "Find Feature Shapes" filters in my pipeline, where I'm trying to extract individual grain statistics using 2D EBSD data in a .ctf file. In the output CSV file, I can see three columns for Axis Euler Angles and another three columns for Average Euler Angles. I noticed that all the values in the three columns of Average Euler Angles are greater than zero, but in the Axis Euler Angles, only one column (AxisEulerAngles_0) has values greater than zero, while the other two columns have zeros for all the features.

I read the description in the documentation, but I'm still struggling to understand the difference between these two statistics. Can you explain the difference between these two statistics and why there is only one non-zero value for Axis Euler Angles? I feel like there should be two values since this is 2D data, so two axes.

Thanks and regards,

Maliesha

[Michael Jackson]

Dear Maliesha,

 The “Average Euler Angle” is the average crystallographic orientation of the grain/feature. 

The “Axis Euler Angle” is the orientation of the major axis of an ellipsoid fit around the feature. It describes the morphological orientation of the feature/grain. 

In 2D, the orientation of the major axis of the ellipsoid will always be co-planar with the XY plane which means that a simple rotation around the Z Axis is all that is needed to describe the orientation. Since the Euler angles are expressed in the Bunge convention(ZXZ), then you will ONLY get a non-zero value in the first component of the Axis Euler Angle.

--
Mike Jackson                    mike.j...@bluequartz.net
BlueQuartz Software         www.bluequartz.net

President/Owner               Dayton, Ohio

Principal DREAM.3D Developer

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[Maliesha Kalutotage]

Hi Michael,

Got it, thank you for the explanation.

Regards,

Maliesha