Importing and Exporting ODF Data

Explains how to read and write ODFs to a data file

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Define an Model ODF
Save as .mat file
Export as an generic ASCII file
Export an ODF to an MTEX ASCII File
Export to VPSC format
Import ODF Data using the import wizard
Importing EBSD data using the method loadODF

MTEX support the following formats for storing and importing of ODFs:

Define an Model ODF

We will demonstrate the the import and export of ODFs at the following sample ODF which is defined as the superposition of several model ODFs.

cs = crystalSymmetry('cubic');
mod1 = orientation('axis',xvector,'angle',45*degree,cs);
mod2 = orientation('axis',yvector,'angle',65*degree,cs);
model_odf = 0.5*uniformODF(cs) + ...
  0.05*fibreODF(Miller(1,0,0,cs),xvector,'halfwidth',10*degree) + ...
  0.05*fibreODF(Miller(0,1,0,cs),yvector,'halfwidth',10*degree) + ...
  0.05*fibreODF(Miller(0,0,1,cs),zvector,'halfwidth',10*degree) + ...
  0.05*unimodalODF(mod1,'halfwidth',15*degree) + ...
  0.3*unimodalODF(mod2,'halfwidth',25*degree);
plot(model_odf,'sections',6,'silent')

Save as .mat file

The most simplest way to store an ODF is to store the corresponding variable odf as any other MATLAB variable.

% the filename
fname = fullfile(mtexDataPath, 'ODF', 'odf.mat');
save(fname,'model_odf')

Importing a .mat file is done simply by

load(fname)

Export as an generic ASCII file

By default and ODF is exported in an ASCII file which consists of a large table with four columns, where the first three column describe the Euler angles of a regular 5� grid in the orientation space and the fourth column contains the value of the ODF at this specific position.

% the filename
fname = fullfile(mtexDataPath, 'ODF', 'odf.txt');

% export the ODF
export(model_odf,fname,'Bunge')

Other Euler angle conventions or other resolutions can by specified by options to export. Even more control you have, if you specify the grid in the orientation space directly.

% define a equispaced grid in orientation space with resolution of 5 degree
S3G = equispacedSO3Grid(cs,'resolution',5*degree);

% export the ODF by values at these locations
export(model_odf,fname,S3G,'Bunge','generic')

Export an ODF to an MTEX ASCII File

Using the options MTEX the ODF is exported to an ASCII file which contains descriptions of all components of the ODF in a human readable fassion. This format can be imported by MTEX without loss.

% the filename
fname = [mtexDataPath '/ODF/odf.mtex'];

% export the ODF
export(model_odf,fname,'Bunge','MTEX')

Export to VPSC format

TODO!!!

Import ODF Data using the import wizard

Importing ODF data into MTEX means to create an ODF variable from data files containing Euler angles and weights. Once such an variable has been created the data can be analyzed and processed in many ways. See e.g. ODFCalculations. The most simplest way to import ODF data is to use the import wizard, which can be started either by typing into the command line

import_wizard('ODF')

or using from the start menu the item Start/Toolboxes/MTEX/Import Wizard. The import wizard provides a gui to import data of almost all ASCII data formats and allows to save the imported data as an ODF variable to the workspace or to generate a m-file loading the data automatically.

Importing EBSD data using the method loadODF

A script generated by the import wizard typically look as follows.

% define crystal and specimen symmetry
cs = crystalSymmetry('cubic');

% the file name
fname = [mtexDataPath '/ODF/odf.txt'];

% TODO: write about halfwidth and the missing 1-1 relationship between ODF
% and single orientations.
% the resolution used for the reconstruction of the ODF
res = 10*degree;

% load the data
odf = loadODF(fname,cs,'resolution',res,'Bunge',...
  'ColumnNames',{'Euler 1','Euler 2','Euler 3','weights'});

% plot data
plot(odf,'sections',6,'silent')
  Interpolating the ODF. This might take some time...
   maximum error during interpolating ODF: 0.052
   mean error during interpolating ODF   : 0.0081
progress: 100%

So far ODFs may only exported from and imported into ASCII files that consists of a table of orientations and weights. The orientations may be given either as Euler angles or as quaternions. The weight may either represent the value of the ODF at this specific orientation or it may represent the volume of a bell shaped function centered at this orientation.