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FABLE-3DXRD / ImageD11

ImageD11 is a python code for identifying individual grains in spotty area detector X-ray diffraction images.
https://imaged11.readthedocs.io/
GNU General Public License v2.0
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makemap.py introduces a rotation to grain positions in the lab frame for hexagonal systems #282

Closed jadball closed 5 months ago

jadball commented 6 months ago

While processing some recent DLS data (using latest ImageD11 stable from PyPI), I found an interesting discrepancy between our indexing for a cubic symmetry sample and a hexagonal symmetry sample.

For a cubic symmetry sample, the grain map and the tomography seem to match well:

image

However, for a hexagonal symmetry sample, it appears that the grain map is rotated somehow:

image

Each of these grain maps were produced using ImageD11.grid_index_parallel from a merged flt file.

jonwright commented 6 months ago

How are you getting the omega angles for the diffraction scan? Does the tomo start/end at the same angles?

To look for an effect of symmetry in makemap, you can just turn it off and use P1 for everything. For now I don't have any idea why the symmetry would have any effect. The co-ordinate system comes from the angles that are input with the frames.