[Insight-users] question on fast marching

[Luis Ibanez]

Hi Quan,

It is not surprising that when you introduce the Laplacian filter
between the reader and the FastMarching filter, your segmentation
will not work as before.

Have you looked at the output of the Laplacian filter ?

You will see that this is equivalent to the trace of the Hessian
of the original image. Therefore, the parameters that you used
for creating the Feature (speed image) that you feed into the
FastMarching filter must be modified accordingly.

Please the ITK Software Guide

    http://www.itk.org/ItkSoftwareGuide.pdf

in particular the section on the FastMarching filter
for a description of what makes a good speed image to
be passed as input to the FastMarching level set method.

If you were planning to use the Laplacian filter as an edge
detector, then you still have to rescale the intensities of
its output in order to make it a suitable speed image for
the FastMarching filter.


   Regards,


       Luis


-------------------------
qxue at jouy.inra.fr wrote:
> Hello, ITK users:
> 
>     I am using FastMarchingImageFilter to do segmentation.
>     If I use it directly after reading the file, everything is fine. However,
> when  I add LaplacianRecursiveGaussianImageFilter into the pipeline
> (ReadFileFilter->LaplacianGaussianFilter->FastMarchingFilter->WriterFileFilter),
> there will be result, that is, the whole image is black.
>     Thanks in advance.
> 
> Quan
> 
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk.org
> http://www.itk.org/mailman/listinfo/insight-users
>