[Insight-users] Where is the Polygon Scan Converter?

[Luis Ibanez]

Hi Frank,

Then filter that you may want to use is the

    PolylineMask2DImageFilter

http://www.itk.org/Insight/Doxygen/html/classitk_1_1PolylineMask2DImageFilter.html

It uses the BresenhamLine iterator internally
in order to fill in the regions of a polygon.

You will find a test for it under

     Insight/Testing/Code/BasicFilter/
              itkPolylineMask2DImageFilterTest.cxx


Regards,


    Luis



---------------------
Frank Miller wrote:
> James,
> 
> Thanks for the reply.  I knew there must be a way to do this with code 
> currently in the library.
> 
> The polygon scan converter code crashed for me too until I made a few 
> changes. I haven't taken the time to really understand what was wrong 
> and what I did but it seems to work for me now.  If I find some free 
> time I might take a closer look at what I did and if it turns out to 
> actually be a solution Ill submit a patch.
> 
> For now Im going to give your suggestion a try because I am interested 
> in trying it in the 3D case and speed is not critical to my application.
> 
> Thanks again,
> 
> Frank
> 
> Miller, James V (Research) wrote:
> 
>> Frank,
>>
>> The polygon scan converter code needed some work before it could be
>> incorporated into the toolkit. I tried to do it quickly before the 
>> last release but couldn't finish it in time.  It currently crashes
>> when I try to use it. 
>> I will try to get this operational and included in the toolkit for
>> the next release which is scheduled for the end of November.
>>
>> A brute force way to do what you want is to construct a 
>> PolygonSpatialObject
>> and use a SpatialObjectToImageFilter to generate the initial implicit
>> function.  This is not very efficient when polygon is small relative 
>> to the size of image, but it will do what you need.
>>
>> Jim
>>
>>
>>
>> -----Original Message-----
>> From: insight-users-bounces+millerjv=crd.ge.com at itk.org
>> [mailto:insight-users-bounces+millerjv=crd.ge.com at itk.org]On Behalf Of
>> Frank Miller
>> Sent: Friday, October 21, 2005 10:16 AM
>> To: insight-users at itk.org
>> Subject: [Insight-users] Where is the Polygon Scan Converter?
>>
>>
>> Greetings,
>>
>> Im using level set methods to work on a segmentation problem and wrote 
>> a little function that I think this community would be interested in.
>>
>> Problem
>> -------
>>
>> The standard way to generate an initial implicit function is to create 
>> a distance map from a set of seed points using the 
>> FastMarchingImageFilter or the DanielssonDistanceMapImageFilter. It 
>> would be nice to be able to generate the initial implicit function 
>> given a level set. In other words, to have a method to generate an 
>> implicit function that has an arbitrary polygon for its zero level set.
>>
>> Solution
>> --------
>>
>> I would expect many people would want to implement something like this 
>> and it is possible the solution is already in ITK and I just have not 
>> found it.  If this is the case, please point me in the right direction.
>>
>> My solution is to create an image with zeros everywhere outside the 
>> polygon, and non-zeros inside the polygon, and feed this to the 
>> SignedDanielssonDistanceMapImageFilter.  I generate this binary image 
>> from a polygon scan conversion iterator written by Benjamin King and 
>> submitted in this post.
>>
>> http://public.kitware.com/pipermail/insight-users/2005-June/013614.html
>>
>> Questions
>> ---------
>>
>> The code for the polygon scan conversion iterator does not seem to be 
>> in the library (I checked the 2.0.0 release and the current version in 
>> CVS).  Has the name been changed or has it not been integrated yet?
>>
>> Does someone need to volunteer to add this code to the library?  I 
>> might be able to do this.
>>
>> Frank
>> _______________________________________________
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>> Insight-users at itk.org
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> 
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