cleanUpPseudoSym

cleanUpPseudoSym edit page

cleanUpPseudoSym Corrects pseudo-symmetry artifacts in a single phase using tortuosity.

A pseudo symmetry is a rotation which is not a symmetry of the crystal but maps the diffraction pattern almost onto itself, such that the indexing picks between the two solutions at random. The resulting boundaries follow the indexing noise and are therefore much more tortuous, i.e. much longer relative to the distance between their end points, than real grain boundaries. This command merges all grains separated by such a boundary and rotates the affected pixels by the pseudo symmetry.

Since the phase to be corrected is determined by the symmetry of mori, only one phase is treated per call. To clean up pseudo-symmetries in multiple phases, run this function for each phase individually. Grain boundaries should not have been smoothed before, as this destroys exactly the tortuosity the detection is based on.

Syntax

[ebsd, grainsM, numChanged] = cleanUpPseudoSym(ebsd, grains, mori)
[ebsd, grainsM, numChanged] = cleanUpPseudoSym(ebsd, grains, mori, 'threshold', 1.5)

Input

`ebsd`	`EBSD object, with grainId set by EBSD.calcGrains`
`grains`	`grain2d object`
`mori`	`rotation or orientation (array of pseudo-symmetries, same CS and SS)`

Output

`ebsd`	`updated EBSD object`
`grainsM`	`merged grain2d object`
`numChanged`	`number of pixels that changed orientation`

Options

`'delta'`	`Tolerance for boundary misorientation angle to match pseudo-symmetry (default: 2*degree)`
`'threshold'`	`Minimum tortuosity (boundary length / straight distance) to trigger merge (default: 1.5)`

Example

mtexdata forsterite
ebsd = ebsd('indexed');
[grains,ebsd] = calcGrains(ebsd,'angle',10*degree,'minPixel',5);

ebsd = EBSD (y↑→x)
 
 Phase  Orientations     Mineral         Color  Symmetry  Crystal reference frame
     0   58485 (24%)  notIndexed          none                                   
     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)

the pseudo hexagonal oxygen sublattice of olivine

psSym = orientation.byAxisAngle(Miller(1,0,0,ebsd('Fo').CS,'uvw'),[60 120]*degree);

[ebsd,grains] = cleanUpPseudoSym(ebsd,grains,psSym)