[Insight-users] make an initial level-set

[Joshua Cates]

You may also use the binary image directly and set the isosurface value
for the interface to an appropriate value.  For example, if you have a
binary image of 0s and 1s, then you can call
filter->SetIsoSurfaceValue(0.5), where "filter" is your level-set based
segmentation filter. The same positive-negative convention applies.  You 
can call filter->ReverseExpansionDirection() to effectively reverse the 
positive-negative convention.

Josh.

______________________________
 Josh Cates			
 Scientific Computing and Imaging Institute
 University of Utah
 (801) 587-7697
 http://www.sci.utah.edu/~cates


On Wed, 26 May 2004, Charl P. Botha wrote:

> Toon Huysmans wrote:
> >     I think I have a very simple question: how do I make an initial 
> > level-set form a binary image, where black is outside and white is 
> > inside the initial segmentation.
> >  
> >     Can I directly use the binary image or should I make it a disctance map?
> 
> The 0-value level-set of you initial level-set function should be the 
> interface that you want to involve. Your initial level-set function does 
> not have to be a distance field (the ITK level set code will take care 
> of creating the distance field).
> 
> In other words, for your specific binary image, change the white inside 
> your object to -1 and the black outside to 1.  The convention is < 0 on 
> the inside and > 0 on the outside.  This means for example that a 
> positive propagation factor will result in an outwards (i.e. 
> inflationary) propagation speed term.
> 
> HTH,
> Charl
> 
> -- 
> charl p. botha http://cpbotha.net/ http://visualisation.tudelft.nl/
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