[Insight-users] elongation implementation not matching its definition

[Cagatay Bilgin]

I just corrected this and submitted for review. Thank you for the help.

Cheers,
C. Cagatay Bilgin


On Thu, Aug 22, 2013 at 3:08 PM, Bradley Lowekamp <blowekamp at mail.nih.gov>wrote:

> I agree this is a documentation error. Wikipedia seems to agree with the
> source code:
>
>
> http://en.wikipedia.org/wiki/Shape_factor_(image_analysis_and_microscopy)#Elongation_shape_factor
>
> On Aug 22, 2013, at 5:13 PM, Cagatay Bilgin <bilgincc at gmail.com> wrote:
>
> Hello everyone,
>
> Either I am missing something or the write up about the elongation is not
> matching the actual implementation.
>
> "elongation is computed as the ratio of the largest principal moment by
> the smallest principal moment. "
>
> however in itkShapeLabelMapFilter.hxx elongation is defined as largest
> principal moment / second largest principal moment. In 3D the definition
> and the implementation becomes inconsistent.
>
> from itkShapeLabelMapFilter.hxx
> 331  elongation = vcl_sqrt(principalMoments[ImageDimension - 1] /
> principalMoments[ImageDimension - 2]);
> 332  flatness = vcl_sqrt(principalMoments[1] / principalMoments[0]);
>
> Cheers,
> C. Cagatay Bilgin
>
> --
> Cemal Cagatay Bilgin, PhD
> Life Sciences Division
> Lawrence Berkeley National Lab
> MS977, One Cyclotron Road
> Berkeley, CA 94720, USA
> Email: ccbilgin at lbl.gov
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-- 
Cemal Cagatay Bilgin, PhD
Life Sciences Division
Lawrence Berkeley National Lab
MS977, One Cyclotron Road
Berkeley, CA 94720, USA
Email: ccbilgin at lbl.gov
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