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tend-evq - Man Page

quantize directions of diffusion


tend evq [-c <evec index>] -a <aniso> [-ns] [-i <nin>] [-o <nout>]


Quantize directions of diffusion. Because VTK doesn’t do multi-dimensional colormaps, we have to quantize directions of diffusion (usually just the principal eigenvector) in order to create the usual XYZ<->RGB coloring. Because eigenvector directions are poorly defined in regions of low anisotropy, the length of the vector (pre-quantization) is modulated by anisotropy, requiring the selection of some anisotropy metric.


-c <evec index>

Which eigenvector should be quantized:

0” for the direction of fastest diffusion (eigenvector associated with largest eigenvalue), “1” or “2” for other two eigenvectors (associated with middle and smallest eigenvalue) (int); default: “0

-a <aniso>

Which anisotropy metric to scale the eigenvector with. All the Westin metrics come in two versions. Currently supported:

  • cl1”, “cl2”: Westin’s linear
  • cp1”, “cp2”: Westin’s planar
  • ca1”, “ca2”: Westin’s linear + planar
  • cs1”, “cs2”: Westin’s spherical
  • ct1”, “ct2”: GK’s anisotropy type (cp/ca)
  • ra”: Basser/Pierpaoli relative anisotropy/sqrt(2)
  • fa”: Basser/Pierpaoli fractional anisotropy
  • vf”: volume fraction = 1-(Basser/Pierpaoli volume ratio)
  • tr”: trace

Don’t attenuate the color by anisotropy. By default (not using this option), regions with low or no anisotropy are very dark colors or black

-i <nin>

input diffusion tensor volume; default: “-

-o <nout>

output image (floating point) (string) default: “-

See Also


Referenced By


April 2021