[Insight-users] Fast marching to calculate distance map

[siqi chen]

Hi, ITKers,

I am using FastMarchingImageFilter to calculate a distance map to a set of
points which have non-integer coordinates and I want the result to be as
accurate as possible. Here is what I did, but the result is not very
accurate.

First I find the integer points which are the neighbors of the target points
and set these integer points as trial points. Then I use some interpolation
method to initialize the distance from these trial points to the target
points, which are assumed to be exactly correct. The TrialPoints in the
FastMarchingImageFilter is defined as this set of trial points and their
corresponding distances to the target points. The AlivePoints is empty. When
I check the result distance map, I find that the distance value of these
trial points are changed, they are no longer what their initial states are.
Therefore, the iso curve deviate the original input a little bit.

Am I missing something?

Thanks
Siqi
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