B.2 Contents of the DDT file

DDT file format, for each voxel, with vij the eigenvector entries and eigenvalues λ1 > λ2 > λ3, there are 12 values:

[                                                  ]
 v1x  v1y  v1z  v2x  v2y  v2z  v3x v3y  v3z λ 1 λ2  λ3

If you want to reconstruct the tensor D, use the following:

DE =
(              )
  Dxx  Dxy  Dxz
( Dyx  Dyy  Dyz)
  Dzx  Dzy  Dzz(            )
 v1x  v2x v3x
(v1y  v2y v3y)
 v1z  v2z v3z = (            )
 v1x  v2x v3x
(v1y  v2y v3y)
 v1z  v2z v3z(           )
  λ1   0  0
(  0  λ2  0 )
   0   0  λ3
and
DEET = D = EΛET
ET = Λ = ETDE.