[Insight-users] "Forbidden area" in Level Set?

[Sah Rayman]

Joshua,

I got the idea! Thanks.

--- Joshua Cates <cates at sci.utah.edu> wrote:
> Hello Sah,
> 
> Your instincts are correct.  To keep the time step
> reasonable, try
> modifying your speed term so that it goes more
> smoothly to zero at the
> boundaries of the regions you that you don't wish
> the surface to enter.  
> See also the itkAntiAliasBinaryImageFilter for clues
> on how to apply
> constraints to the evolution of the level-sets
> (you'll have to override
> some methods in your subclasses of
> SegmentationLevelSetImageFilter).
> 
> Josh.
> 
> ______________________________
>  Josh Cates			
>  Scientific Computing and Imaging Institute
>  University of Utah
>  (801) 587-7697
>  http://www.sci.utah.edu/~cates
> 
> 
> On Fri, 5 Mar 2004, Sah Rayman wrote:
> 
> > I wish my level set never evolve to some area in
> the
> > image. Those area was obtained by another
> application.
> > What can I do?
> > 
> > I tried to put a negative speed for those areas.
> But
> > level set will balance with other factors, and
> still
> > enter those region. 
> > 
> > When I increase the negative speed to a very large
> > value(compared to other speeds), it now don't
> enter
> > those region. But whenever the edge touches those
> > region, speed for everywhere else decrease a lot.
> > (Because "timeStep =
> > df->ComputeGlobalTimeStep(globalData)" will be
> very
> > small so that it's stable)
> > 
> > Is there any other way mark a region
> "non-enterable"?
> > 
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> 


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