[Insight-users] elongation implementation not matching its definition

[Bradley Lowekamp]

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
> _____________________________________
> Powered by www.kitware.com
> 
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
> 
> Kitware offers ITK Training Courses, for more information visit:
> http://www.kitware.com/products/protraining.php
> 
> Please keep messages on-topic and check the ITK FAQ at:
> http://www.itk.org/Wiki/ITK_FAQ
> 
> Follow this link to subscribe/unsubscribe:
> http://www.itk.org/mailman/listinfo/insight-users

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20130822/7c509a99/attachment.htm>