[Insight-users] Hi everyone about volume fraction from levelset

[Luis Ibanez]

Hi Wediong,

First of all, please note that the concept of pixel in ITK is different from
the one used in VTK, and in descriptions similar to the marching cubes
method, for example.

You seem to be assuming that a pixel is the cubic-like volume surrounded
by eight values.  In ITK this is not what we call a pixels. Instead we
assume that a pixel is cubic-like volume surrounding one data point, as
you would do in sampling theory.

That said,

If you want to compute the volume fraction defined inside that space
in-between eight nodes (eight ITK pixels) an cut by the Zero level
surface, you may want to reuse the cases of the Marching Cubes
algorithm.

             http://en.wikipedia.org/wiki/Marching_cubes

We don't quite have a ready-to-use implementation of those calculations,
therefore, if you implement one, that will be a great contribution to
submit to the Insight Journal

                    http://www.insight-journal.org/


     Regards,


          Luis


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On Mon, Oct 19, 2009 at 4:53 AM, Wei-Dong Lian <weidong.lian at gmail.com> wrote:
> Hi everyone,
>
> I am employing LevelSet Image segmentation to segmente a 3D image for a
> two-phases material and then predict the volume fraction of each phase. The
> problem is that , for example, I know eight levelset values of corner points
> of a cube. So theoretically, we could get the zero level set surface by
> which the cube was divided into two phases, so we could have the volume
> fraction of one phase. Now I am wondering if these exists some formulas to
> do this, or in itk these exists some "objects" to calculate the volume
> fraction.
> Any suggestion will be appreciated.
> Thanks in advance,
> Regrads,
> wediong
>
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