[vtkusers] a sinple question about vtkMarchingcubes

[Goodwin Lawlor]

I could be wrong but...  if its a segmented volume and the values 100 and
200 arbitrarily denote different objects, is it not better to threshold to a
binary B&W volume (values of 0 and 255) for each "tissue mask" and then use
a Marching Cubes value of 127.5 ? Mcubes uses the Value and linear
interpolation to extract the isosurface so using the original "tissue mask"
value may give (slightly) arbitrary results. A volume from a CT dataset
would be different, though, and wouldn't necessarily have to be thresholded
(unless you wanted to get rid of some artifacts....)

(e.g., from segented8.tcl)
.
.
.

vtkImageThreshold selectTissue
    selectTissue ThresholdBetween 100 100; # or 200 200
    selectTissue SetInValue 255
    selectTissue SetOutValue 0
    selectTissue SetInput [reader GetOutput]

vtkMarchingCubes mcubes;
    mcubes SetInput [selectTissue GetOutput]
   eval mcubes SetValue 0 127.5



Goodwin

Mech Eng Dept
University College Dublin

----- Original Message -----
From: Wenqin Wang <wenqin_w at yahoo.com>
To: <vtkusers at public.kitware.com>
Sent: Monday, December 04, 2000 9:25 PM
Subject: [vtkusers] a sinple question about vtkMarchingcubes


> Hi, all,
>   I am new in VTK. I am trying to visualize a volume
> in VTK. The valume is already segmented, with one
> value is 100, and the other is 200. What I tried to do
> is to extract those two surfaces using marching cubes.
>
>   But I cann't understand how to set the value for the
> marching cubes, the value I should use is 50.0 or
> 100.0?
>
>   Thanks for help.
>
>   Wendy
>
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