[Insight-users] Re: [Insight-developers] bug report on DeformableModelSimplexMesh application

[Luis Ibanez]

Hi Defeng,

Can you please post in a public web site the image that
you are using as input, and the full set of parameters
that you are using for running this application ?

Otherwise it is very hard for us to figure out how far
from the edge of the image you are seeing the final
contour stopping.

Please give use a very clear sequence of step that we
could follow to reproduce your experience here.



   Thanks


      Luis


-------------------
Defeng WANG wrote:
> Hi, Leila,
> 
> Thanks for your reply. It seems that the parameters in the UI of
> DeformableModelSimplexMesh are not related to the gradient calculation. I
> read the source code involved in DeformableModelSimplexMesh. As for the
> gradient calculation, three filters are used successively as follows,
> 
>  m_GradientMagnitude->SetInput(m_CastImage->GetOutput() );
>  m_GradientMagnitude->SetSigma(0.5);
> 
>  m_SigmoidImage->SetInput( m_GradientMagnitude->GetOutput());
>  m_SigmoidImage->SetOutputMinimum(0);
>  m_SigmoidImage->SetOutputMaximum(1);
>  m_SigmoidImage->SetAlpha(230);
>  m_SigmoidImage->SetBeta(1300);
> 
>  m_GradientFilter->SetInput( m_SigmoidImage->GetOutput());
>  m_GradientFilter->SetSigma( 0.5);
> 
> 
> I have taken a look at the final gradent image. It seems that it is good 
> enough to describe the
> edge or boundary of a sphere. So what do you think of this problem existing
> in this simple example?
> 
> 
> Look forard to your response.
> 
> Best wishes,
> Defeng
> 
> ----- Original Message ----- From: "Leila Baghdadi" 
> <baghdadi at phenogenomics.ca>
> To: "Defeng WANG" <dfwang at cse.cuhk.edu.hk>
> Cc: <insight-developers at itk.org>; <insight-users at itk.org>
> Sent: Thursday, January 31, 2008 10:54 PM
> Subject: Re: [Insight-developers] bug report on 
> DeformableModelSimplexMesh application
> 
> 
>> Hi Defeng,
>>
>> Yes I have used that code many a times. I am not sure if I understand
>> what you mean by "it does not converge".
>>
>> My understanding of deformable models is
>>
>> 1. you must make sure your gradient image is created properly. Use
>> paraview to look at the vector image
>>
>> 2. you must play with the parameters to get the model to converge,
>>
>> This is a specific type of deformable models which uses simplex mesh.
>> I suggest you read about this algorithm first. This is developed based
>> on the paper by Herve Delingette of INRIA france.
>>
>>
>> Leila
>>
>> On Thu, 2008-31-01 at 22:29 +0800, Defeng WANG wrote:
>>
>>> Hello, ITK users and developers,
>>>
>>> I found that DeformableModelSimplexMesh, provided in
>>> InsightApplications-3.4.0, does not converge. It seems that the
>>> deformable mesh will not stop near the boundary of one object to be
>>> segmented. I tried a very simple volume data set containing a sphere
>>> only. The initial mesh I used is a spherical simplex mesh inside it.
>>> However, by increasing the number of iterations, the mesh will
>>> continue to expand until it reaches outside of the image and the
>>> program reports error.
>>>
>>> Is there anybody tried this program successfully before? Or anybody
>>> knows how to adjust the parameters properly to get right segmentation?
>>>
>>> Best wishes,
>>> Defeng
>>> _______________________________________________
>>> Insight-developers mailing list
>>> Insight-developers at itk.org
>>> http://www.itk.org/mailman/listinfo/insight-developers 
> 
> 
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