[Insight-users] level set stopping criteria

[Burak Özkalaycı]

Dear all,

I am making some level set evolution experiments using ITK and I could
not figure out how the RMS change is calculate to stop iteration. I
just initialized the level set with a signed distance function to a
cube and assigned a velocity map which is a bigger cube inside all 0.5
and outside -0.5. The initial cube grows to the bigger one and stops
correctly. In the level set function formulation I just used the
propagation term. The algorithm stops with a RMS error equal to zero.
If the RMS error is just calculated by summing ( Phi(t+1)-Phi(t) )^2
terms at all nodes, than the RMS error may not decrease I think.
Because the other levels like Phi=1 or Phi=-1 should continue to
propagate, if I am not wrong. Can anyone make clear how the RMS error
is calculated? Thank you in advance.


 Burak Ozkalayci

 PhD Student
 Electronic and Information Systems (ELIS-MEDISIP)
 Ghent University Hospital - IBITECH