[Insight-users] Fast Marching for arbitrary interfaces

[Karthik Krishnan]

As Luca mentioned, you can assign time crossing values to the seeds (trial
points).

As an analogy, assigning a seed a value of "-10" in time is roughly
equivalent to translating the initial zero level set at a distance of 10
units away from that seed.

On Mon, May 25, 2009 at 6:25 AM, Luca Antiga <luca.antiga at gmail.com> wrote:

> Hi Armadeep, you should be able to initialize your front with
> FastMarchingImageFilter with different time-crossing values for every trial
> point (i.e. the initial front doesn't have to binary). In your case, you may
> want to set the value of each trial point to the value of the level set at
> that point.
> When you fill your list of trial points, you have to fill out a list of
> "nodes": just call node.SetValue(someValue) in addition to
> node.SetIndex(someIndex) to set the initial time-crossing value at that
> index.
> FastMarchingExtensionImageFilter does more, in that it also extends
> auxiliary variables in addition to the "time-crossing map".
> I hope this helps
>
> Luca
>
>
> On May 25, 2009, at 12:10 PM, Amardeep Singh wrote:
>
> Dear Luis
>
> Thank you very much for your answer!
> I have also thought about using the ShapeDetectionLevelSetImageFilter. But
> in my application, I'm afraid, I am
> interested in the time-crossing map, initialized from an arbitrary front. I
> need to
> use level-sets with an exact narrow-band (for post-processing). So, the
> chamfer distance function which
> is currently used is not exact enough in my case. Instead, I would like to
> use fast marching for reinitialization.
> Therefore I would like to repeat my question:
> Is it correct that the itkIsoContourDistanceImageFilter is a good starting
> point?
> What is the use of the "FastMarchingExtensionImageFilter"?
>
> Thanks a lot!
>
> Best regards
> Amardeep
>
> Luis Ibanez wrote:
>
>
> Hi Amardeep
>
>
>
> The implementation of FastMarching in ITK is initialized using
>
> seed points.
>
>
> If you already have an initial front (as opposed to a set of
>
> seed points) then you can use the
>
>
>              ShapeDetectionLevelSetImageFilter
>
>
> and set the curvature weight to zero. In those conditions this
>
> filter will preform a front propagation similar to Fast Marching.
>
>
>
>
>    Regards,
>
>
>
>       Luis
>
>
>
>
>
> -------------------
>
> Amardeep Singh wrote:
>
> Dear ITK-users
>
>
> In the current implementation of the fast marching filter, the initial
> surface that is to be propagated
>
> has to be a binary interface (Please, correct me if I'm wrong).
>
> I am wondering if there is a way to apply the fast marching filter in ITK
> to arbitrary inital fronts as it is described
>
> by Sethian in his paper "A fast marching level set method for monotonically
>
> advancing fronts" (PNAS, February 1996). If such a functionality does not
> exist at the moment:
>
> Would you agree that the itkIsoContourDistanceImageFilter might be a good
> starting point to implement the initial
>
> calculation of the signed distances to some arbitrary isosurface? These
> distances might then be used for the fast marching propagation as described
> by Sethian.
>
>
> Thanks a lot!
>
>
> Best regards
>
> Amardeep
>
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>
> --
> Luca Antiga, PhD
> Head, Medical Imaging Unit,
> Biomedical Engineering Department,
> Mario Negri Institute.
> mail: Villa Camozzi, 24020, Ranica (BG), Italy
> phone: +39 035 4535-381
> email: antiga at marionegri.it
> web: http://villacamozzi.marionegri.it/~luca<http://villacamozzi.marionegri.it/%7Eluca>
>
>
> _____________________________________
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>
> Visit other Kitware open-source projects at
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