[Insight-users] Obtaining shape information from a region

[Aster.Wardhani at csiro.au]

Thanks for your help & suggestion of using a mesh. I am trying now to
use the BinaryMask3DMeshSource and trying to input the result from
connectedThresholdFilter to this object. This does not seem to work to
directly connecting them in the pipeline. Do I have to somehow convert
the filter output to a binary image first? I use casting but still not
working.

-----Original Message-----
From: Luis Ibanez [mailto:luis.ibanez at kitware.com] 
Sent: Wednesday, 24 August 2005 1:33 AM
To: Wardhani, Aster (ICT Centre, e-Health Res Centre)
Cc: insight-users at itk.org
Subject: Re: [Insight-users] Obtaining shape information from a region


Hi Aster,

There are filters that will extract the pixels from
the boundary and set them on in an outptu image:

SimpleContourExtractorImageFiler
http://www.itk.org/Insight/Doxygen/html/classitk_1_1SimpleContourExtract
orImageFilter.html

You can also use the BinaryMaskToNarrowBandImageFilter
that will return you a PointSet with all the points
that are located at a selected distance from the edge
of your segmented object.
http://www.itk.org/Insight/Doxygen/html/classitk_1_1BinaryMaskToNarrowBa
ndPointSetFilter.html


However, I would strongly discurage you from encoding
the information of your segmentation in a simple list
of points, because you will lose all the connectivity
information, which is very expensive to recover from
just a cloud of points.


Of course, it all depends on what is your final goal....


If you are looking for a Mesh representation of your
object, then you should consider to include not only
the points (locations of pixels as returned by the
IndexToPhysicalPoint() method in the itk::Image), but
also the neighborhood information.


You may want to read the "Data Representation" Chapter
from the ITK Software Guide:

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


in order to get familiar with the mechanisms for
representing Meshes.



   Regards



      Luis




------------------------------
Aster.Wardhani at csiro.au wrote:
> Hi Luis,
> 
> After I extract a region say using region growing, I'd like to store
points that belong to the region's boundary and also points that belong
to the internal region's areas. Does that make sense? Does the filter
provide a method to return a list of points? Or do I need to do manually
interate all pixels in the output image then push each pixel as a point
into a list ?
> 
> Thanks,
> 
> Aster.
> 
> -----Original Message-----
> From:	Luis Ibanez [mailto:luis.ibanez at kitware.com]
> Sent:	Tue 8/23/2005 9:09 AM
> To:	Wardhani, Aster (ICT Centre, e-Health Res Centre)
> Cc:	insight-users at itk.org
> Subject:	Re: [Insight-users] Obtaining shape information from a
region
> 
> Hi Aster,
> 
> I'm afraid that you question is too vague in
> order for us to give you any useful feedback.
> 
> Shape analysis is a wide field and you should
> usually start by framing the goal/purpose of
> your shape analysis task.
> 
> Maybe a description of the context of your problem
> would help....
> 
> 
>    Regards,
> 
> 
> 
>      Luis
> 
> 
> -------------------------------
> Aster.Wardhani at csiro.au wrote:
> 
>>Hi,
>>
>>I've just done some segmentation using connected component filter 
>>(region grow with a seed point). What's the best way to analyse the 
>>shape of the region, i.e getting:
>>
>>-       its boundary
>>-       points that belong to the region.
>>
>>
>>----------------------------------------------------------------------
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>>
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> 
> 
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