For running fitglobalgrain.py or fitgloball.py, to refine the global parameter of the far-field detector from an undeformed polycrystalline sample the following commands are mandatory:
xyz | 1 # refine positions |
rod | 1 # refine orientaions |
eps | 0 # do not refine strains, use undeformed material! |
w | fit omega stage tilt parameter wy (0=no/1=yes), default: 0 |
tilt | fit detector tilt parameters tx, ty, tx (0=no/1=yes), default: 0 |
pixel | fit pixel size py and pz (0=no/1=yes), default: 0 |
center | fit detector centre along y-axis, cy (0=no/1=yes), default: 0 |
L | fit sample-to-detector distance (0=no/1=yes), default: 0 |
title | same use as stated earlier: 'my very special farfield global parameter fit' |
structure_file | name of file containing crystallographic information, possible formats: .cif or .pdf |
res_file | name of .gff file from which to read starting grain parameters (optional, NB! overrules information from log_file) |
tol_rotpos | tolerance for orientation and position refinement, default: 1e-2 |
tol_global | tolerance for global parameter refinement, default: 1e-2 |
rej_ia | outlier rejection limits, rej_multi and overlap same meaning and defaults as stated for fitallb.py |
rej_vol | |
rej_resmedian | |
rej_resmean | |
rej_multi | |
overlap | |
min_refl | minimum number of reflections to considered refinement meaningful, value in [1,inf], default: 9, but should be increased to around 80% of the expected average number of reflections |
skip | skip refinement of the named grains from the grainspotter.log, values in {1,2,...}, default: None |
The above input files can be used for both fitglobalgrain.py and fitgloball.py.
The fit of the global parameters is performed for 5 grains of undeformed IF steel simulated within an illuminated volume of 0.7x0.7x0.01 mm with random orientations and grain sizes.
The input file of global parameters, if100_globals_wedge.par, has a slight offset in all of these as compared to the values used to simulate the diffraction images.
NB! Note that min_refl is set to 45 for the global parameter refinements while it was 36 for the strain refinement examples above that are performed for the same material and omega ranges.
This is done to only refine the global parameters from the largest and by assumption best determined grains.