Changing the scalar value of a region

Ron Inbar rinbar at
Tue Aug 10 15:50:30 EDT 1999

Hello all!

I have a stack of CT scans of someone's chest.  I'm trying to extract a
model of the lungs using Marching Cubes.  I use a low threshold value to
detect the boundary between air and anything denser than air.  This way I
get the lungs all right, but I also get the outer surface of the man's body.
I was thinking about the following approach to get rid of this unwanted
surface: take a point known to be outside the body, and proceed by
connectivity to identify the region of air surrounding the body.  Then
change the scalar value of every point in this region to something higher
than the threshold.  Marching Cubes can take it from here.

What filter(s) should I use to do this?  I saw that vtkConnectivityFilter
can identify the region, but how can I use it to obtain a
vtkStructuredPoints with the same dimensions as the original volume, but
with different scalars?

Your help will be greatly appreciated,


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