MIL Fabric tensors

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Behdad Pouran

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May 6, 2015, 6:38:07 AM5/6/15
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Dear Michael,

After activating the record eigen in anisotropy window I received a few numbers including the elements of eigenvector and eigenvalues. Could you please clarfiy if these numbers represent the MIL fabric tensor or do I have to add something else in the code to enable getting MIL fabric tensor?


Thank you very much.


Kind regards,
Behdad



Michael Doube

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May 6, 2015, 7:07:14 AM5/6/15
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Hi Behdad,

> After activating the record eigen in anisotropy window I received a few numbers including the elements of eigenvector and eigenvalues. Could you please clarfiy if these numbers represent the MIL fabric tensor or do I have to add something else in the code to enable getting MIL fabric tensor?

Yes, these values are the eigenvector and eigenvalue matrices of the fabric tensor. The eigenvectors indicate the orientation of the tensor (and thus, the orientation of the texture in your input image), while the eigenvalues relate to the spacing of the texture elements in each direction indicated by the columns of the eigenvectors. DA is calculated from the eigenvalues, while the eigenvectors are helpful for understanding the directionality of the anisotropy (e.g., to rotate the image so that the fabric tensor is aligned with the image (x, y, z) coordinate frame). For more details of the DA calculation have a look at the harriganMann() method in Anisotropy.java

https://github.com/mdoube/BoneJ/blob/master/src/org/doube/bonej/Anisotropy.java#L733

And have a read of Harrigan & Mann (1984)

http://dx.doi.org/10.1007/BF00540446

Cheers,

Michael

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