Select EBSD data edit page

In this section we discuss how to select specific EBSD data by certain properties. Let us first import some example EBSD data using the command mtexdata.

mtexdata forsterite
ebsd = EBSD
 
 Phase  Orientations     Mineral         Color  Symmetry  Crystal reference frame
     0   58485 (24%)  notIndexed                                                 
     1  152345 (62%)  Forsterite  LightSkyBlue       mmm                         
     2   26058 (11%)   Enstatite  DarkSeaGreen       mmm                         
     3   9064 (3.7%)    Diopside     Goldenrod     12/m1       X||a*, Y||b*, Z||c
 
 Properties: bands, bc, bs, error, mad
 Scan unit : um
 X x Y x Z : [0 36550] x [0 16750] x [0 0]
 Normal vector: (0,0,1)

These data consist of three indexed phases, Forsterite, Enstatite and Diopside. The not indexed phase called not Indexed. The phases can be visualized by

close all; plotx2east
plot(ebsd)

Selecting a certain phase

After import the EBSD data are stored in the variable ebsd which is essentially a long list of x and y values together with phase information and orientations. In order to restrict this list to a certain phase just use the mineral name as an index, i.e.

ebsd('Forsterite')
ans = EBSD
 
 Phase   Orientations     Mineral         Color  Symmetry  Crystal reference frame
     1  152345 (100%)  Forsterite  LightSkyBlue       mmm                         
 
 Properties: bands, bc, bs, error, mad
 Scan unit : um
 X x Y x Z : [0 36550] x [0 16750] x [0 0]
 Normal vector: (0,0,1)

contains only the Forsterite measurements. In order to extract a couple of phases, the mineral names have to be grouped in curled parenthesis.

ebsd({'Fo','En'})
ans = EBSD
 
 Phase  Orientations     Mineral         Color  Symmetry  Crystal reference frame
     1  152345 (85%)  Forsterite  LightSkyBlue       mmm                         
     2   26058 (15%)   Enstatite  DarkSeaGreen       mmm                         
 
 Properties: bands, bc, bs, error, mad
 Scan unit : um
 X x Y x Z : [0 36550] x [0 16750] x [0 0]
 Normal vector: (0,0,1)

As an example, let us plot the Forsterite data.

close all
plot(ebsd('Forsterite'),ebsd('Forsterite').orientations)

The data is colorized according to its orientation. By default color of an orientation is determined by its position in the 001 inverse pole figure which itself is colored as

ipfKey = ipfColorKey(ebsd('Forsterite'));
plot(ipfKey)

Restricting to a region of interest

If one is not interested in the whole data set but only in those measurements inside a certain polygon, the restriction can be constructed as follows:

First define a region by [xmin ymin xmax-xmin ymax-ymin] 

region = [5 2 10 5]*10^3;

plot the ebsd data together with the region of interest

close all
plot(ebsd)
rectangle('position',region,'edgecolor','r','linewidth',2)

The command inpolygon checks for each EBSD data point whether it is inside a polygon or not, i.e.

condition = inpolygon(ebsd,region);

results in a large vector of TRUE and FALSE stating which data points are inside the region. Restricting the EBSD data by this condition is done via

ebsd = ebsd(condition)
ebsd = EBSD
 
 Phase  Orientations     Mineral         Color  Symmetry  Crystal reference frame
     0    4052 (20%)  notIndexed                                                 
     1   14093 (69%)  Forsterite  LightSkyBlue       mmm                         
     2   1397 (6.9%)   Enstatite  DarkSeaGreen       mmm                         
     3    759 (3.7%)    Diopside     Goldenrod     12/m1       X||a*, Y||b*, Z||c
 
 Properties: bands, bc, bs, error, mad
 Scan unit : um
 X x Y x Z : [5000 15000] x [2000 7000] x [0 0]
 Normal vector: (0,0,1)

plot

close all
plot(ebsd)

Note, that you can also select a polygon by mouse using the command

poly = selectPolygon

Remove Inaccurate Orientation Measurements

By MAD (mean angular deviation) in the case of Oxford Channel programs, or by CI (Confidence Index) in the case of OIM-TSL programs

Most EBSD measurements contain quantities indicating inaccurate measurements.

close all
plot(ebsd,ebsd.mad)
mtexColorbar

or

close all
plot(ebsd,ebsd.bc)
mtexColorbar

Here we will use the MAD to identify and eliminate inaccurate measurements.

% plot a histogram
close all
histogram(ebsd.mad)
% take only those measurements with MAD smaller then one
ebsd_corrected = ebsd(ebsd.mad<0.8)
ebsd_corrected = EBSD
 
 Phase  Orientations     Mineral         Color  Symmetry  Crystal reference frame
     0    4052 (21%)  notIndexed                                                 
     1   13359 (69%)  Forsterite  LightSkyBlue       mmm                         
     2   1333 (6.9%)   Enstatite  DarkSeaGreen       mmm                         
     3    676 (3.5%)    Diopside     Goldenrod     12/m1       X||a*, Y||b*, Z||c
 
 Properties: bands, bc, bs, error, mad
 Scan unit : um
 X x Y x Z : [5000 15000] x [2000 7000] x [0 0]
 Normal vector: (0,0,1)
close all
plot(ebsd_corrected)