[Insight-users] SignedDanielssonDistanceMapImageFilter

[Ghassan Hamarneh]

Hello Siqi,

You write: "The input is only a binary image with boundary points at  
0, and all other points at 1."
However, according to he documentation: "As a convention, the distance  
is evaluated from the boundary of the ON pixels."
(from http://www.itk.org/Doxygen/html/classitk_1_1SignedDanielssonDistanceMapImageFilter.html 
  )
So, your input image should have boundary pixels set to 1 and all  
other points to 0 (and not the other way around).
HTH,
/Ghassan



On 9-Dec-08, at 7:24 PM, chensiqi wrote:

>
> Hi, ITKers
>
> I got two questions regarding SignedDanielssonDistanceMapImageFilter.
>
> 1. The result I have is not "signed", both the inside and outside  
> distance values are negative.  The input is only a binary image with  
> boundary points at 0, and all other points at 1.  I was wondering  
> how I was wondering how SignedDanielssonDistanceMapImageFilter   
> determine the region of inside and outside.
>
> 2. In Examples of SignedDanielssonDistanceMapImageFilter. cxx,  I  
> notice that the OutputImageType of filter is unsigned short, which I  
> don't quite understand.  The output should contains both negative  
> and positive distance, why use "unsigned" here?
>
> Thanks
> Siqi
>
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