[vtkusers] Re: isosurface extraction question

[Bill Lorensen]

Look at vtkDiscreteMarchingCubes. It works with labelled volume data rather
than grayscale data. Once you have extracted the selected label, you can
smooth the resulting mesh with vtkWindowedSincPolyDataFilter.

Bill


On 10/5/06, Goodwin Lawlor <goodwin.lawlor at ucd.ie> wrote:
>
> kdsfinger at gmail.com wrote:
> > hi, all
> > Assuming I have two neighboring regions, marked as 1 and 2 and the
> > background is 0. I want to find the contour surface of each region.
> > How can I get the contour surface of the region marked as 1? When I
> > use the surface extraction or marching cube methods, I always get the
> > contour of (1 And 2) when I tried to find the contour of region marked
> > as 1. There is no problem to get the contour of region marked as 2.
> > Thanks for comments.
> > zl2k
>
> The answer to that was from the old frog example, still here on the web:
> http://dit.lbl.gov/VTK/GlCache/vtk.cache/examplesTcl/frog/segmented8.tcl
>
> You threshold the segmentation mask to give you a new binary (as in b&w)
> volume containing only the region you want to isocontour. For example:
>
> vtkImageThreshold selectTissue
>      selectTissue ThresholdBetween $TISSUE $TISSUE
>      selectTissue SetInValue 255
>      selectTissue SetOutValue 0
>
> To extract a region of value 1, just set TISSUE to 1. Marching cubes
> then extracts your surface with a value of 127.5
>
> Its worth looking at the full example above.
>
> hth
>
> Goodwin
>
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