[Insight-users] Signed distance map?

[karl at bwh.harvard.edu]

Hi,

You can use itkIsoContourDistanceImageFilter without a narrow band,
and then use itkFastChamferDistanceImageFilter without a narrow band
on the result,
this will give you an approximated (Chamfer) signed distance from
the isocontour that you choose.

For example, if your image is binary (0 or 255), you can choose 128
as the isocontour value:

Parameters for IsoContourDistance:
LevelSetValue --> 128
FarValue --> higher than the maximal distance you want to compute

Parameters for the Chamfer Distance:
input --> result of IsoContourDistance
MaximalDistance --> Maximal distance you want to compute

itkIsoContourDistanceImageFilter will estimate the distance to the
isocontour only for the points very close to it,
itkFastChamferDistanceImageFiler will compute a signed Chamfer distance
based on the previous result.

Hope this help,

Karl Krissian


P.S.: another option is to run twice Danielsson distance, inside and outside
and to shift the results by 0.5 for better accuracy.



> Is there a class in ITK that produces a signed distance map from an
> unsigned image (binary or otherwise)? The Danielsson map filter doesn't
> seem to do so, and the IsoContourDistanceImageFilter requires a signed
> level set image as an input.
>
> It's easy enough to do this with two applications of the Danielsson
> filter on an image and its inverted pair, and subtract the results; I
> was just wondering if there is already a class to do this.
>
> Thanks,
>
> Zach Pincus
>
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