Reference direction for IPF colors?

[Philip Noell]

Hi, 

I'm confused about the reference directions in DREAM3D. I'm working with DCT data of a cylindrical sample. When importing the data, the "X" axis, as defined in Create Geometry, is parallel to the fiber direction (the long axis of the cylinder). When generating IPF colors, do I need to define my reference direction as (100) to have the grains colored relative to the X axis?

Regards,

Philip

[Michael Jackson]

If I am understanding your setup correctly, then this does seem correct. Also, where is the crystal data (Euler Angles) coming from? What instrument is taking the data? You may need to perform some additional manipulations of the Crystal data in order to bring the data into compliance with DREAM.3D reference system. Take a look at this page http://www.dream3d.io/1_UsingDREAM3D/%5BE%5D_Reference_Frame_Notes/ for more information.

 

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[Philip Noell]

Mike, thanks for the information. The diffraction contrast tomography data is collected using a LabDCT system, the Zeiss Xradia Versa 620. I'm a little confused about orientation of the data. The output from DREAM3D seems flipped 180 degrees compared to that shown using the Xnovo software, see the attached images. Why would that be?

Regards,

Philip

[Philip Noell]

Apologies, I forgot the comparison image. The image in my last post is from the Xnovo software. Attached is what DREAM3D gives, this is from the same slice as that shown in the lower left corner of the image in the previous message'

Philip

[Michael Jackson]

Essentially DREAM3D and Xradia are generating images from different relative eye points. Xradia looks like it is looking from the +Z direction onto the bottom layer of data. Now, based on the image form the Xradia system, it looks like they have the long axis of the cylinder oriented along the Z direction with the first layer at Z=0. In reality if the data is encoded into the file as ZYX, where the X Axis is moving the fastest and at the same is the long cylinder axis then to get the same visuals that Xradia is giving you, you will need to rotate the “Sample Reference Frame” inside of DREAM3D. This would be 90 degrees about the 010 axis. That should align the “long axis” with the Z Axis. Export the image or use ParaVIew to view the data from DREAM3D. When you do IPF colors you will have to keep in mind what crystallographic axis you want: X, Y, or Z.

 

Also note that the orientation data that Xradia exports may not be in the same reference frame that DREAM.3D is expecting. Take a look at < http://www.dream3d.io/1_UsingDREAM3D/%5BE%5D_Reference_Frame_Notes/> where we specifically talk about LabDCT systems.

 

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Mike Jackson

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