[Insight-users] Crash in ShapeDetectionLevelSetImageFilter

[Luis Ibanez]

Hi Nils,

You are right in your interpretation of the
behavior for the ShapeDetectionLevelSetFilter.

Increasing the curvature scaling while decreasing
the propagation scaling should make the contour
collapse (contract).

I just verified this behavior using a syntethic
image of a sphere.

Note that in version 1.2 this filter is expecting
the input level set to conform to the convention
of "negative inside" which means that the level
set has negative values 'inside' the contour and
positive values outside the contour.

You may have to push the curvature scaling to
a value higher than 1.0. (e.g. 5.0 or so).

I would avoid to use 0.0 for the propagation
scaling ( in part just for superstition  against
zeros values as parameters). You may want to
try something like 0.1 for the propagation
scaling.

Please verify the convention used by your initial
level set. That may be the cause for the contour
not behaving as expected.


Regards,


    Luis



---------------------
Nils Hanssen wrote:
> Hi Luis,
> 
> I am using the 1.2.0 web release.
> 
> Regards,
> Nils
> 
> 
>>-----Original Message-----
>>From: insight-users-admin at itk . org 
>>[mailto:insight-users-admin at itk . org]On
>>Behalf Of Luis Ibanez
>>Sent: Tuesday, July 08, 2003 3:55 PM
>>To: Nils Hanssen
>>Cc: Insight-users at public . kitware . com
>>Subject: Re: [Insight-users] Crash in 
>>ShapeDetectionLevelSetImageFilter
>>
>>
>>
>>Hi Nils,
>>
>>Are you using a very recent checkout of ITK  ?
>>
>>The level set filters have been reworked in
>>recent days, so it will help us to know if you
>>are experiencing this behavior with the current
>>version or with the version as it was two weeks
>>ago (or before that).
>>
>>Please let us know,
>>
>>    Thanks
>>
>>
>>      Luis
>>
>>
>>------------------------
>>Nils Hanssen wrote:
>>
>>>Hi,
>>> 
>>>I am trying to understand the behaviour of the ShapeDetectionLSIF.
>>>Therefore, I set the propagation-weighting to zero. By setting the 
>>>curvature-weighting to a value of one I would expect that 
>>
>>the inital 
>>
>>>surface is shrinking to a point (I set the MaxRMSError to 
>>
>>zero) and the 
>>
>>>number of iterations very high.
>>> 
>>>The filter is crashing in
>>>SegmentationLevelSetFunction<TImageType, TFeatureImageType>
>>>::PropagationSpeed(const NeighborhoodType &neighborhood, const 
>>>FloatOffsetType &offset) const
>>>[...]
>>>-->  else return ( 
>>
>>static_cast<ScalarValueType>(m_SpeedImage->GetPixel(idx)) ); 
>>// crashing here
>>
>>>[...]
>>> 
>>>When I set the propagation-weighting to - for instance - 0.0001 the 
>>>filter is not crashing, but the contour is not shrinking 
>>
>>according to 
>>
>>>the mean curvature.
>>> 
>>>Is that the correct behaviour of the filter?
>>> 
>>>I would appreciate any suggestions. Thanks!
>>> 
>>> 
>>>Regards,
>>>Nils
>>> 
>>>
>>>-------------------------
>>>Nils Hanssen
>>>Surgical Systems Laboratory
>>>research center c ae sa r
>>>Ludwig-Erhard-Allee 2
>>>53175 Bonn
>>>fon: +49-228-9656-197
>>>fax: +49-228-9656-117
>>>___http://www . caesar . de/ssl_
>>>
>>>
>>> 
>>
>>
>>
>>_______________________________________________
>>Insight-users mailing list
>>Insight-users at itk . org
>>http://www . itk . org/mailman/listinfo/insight-users
>>
> 
> _______________________________________________
> Insight-users mailing list
> Insight-users at itk . org
> http://www . itk . org/mailman/listinfo/insight-users
>