[vtkusers] Visualizing multiple isosurfaces using vtkContourFilter

[Christian Lackas]

* Bill Lorensen <bill.lorensen at gmail.com> [110223 14:49]:

Hi Bill,

would you mind explaining option 2 a little further?
I still fail to convince a mapper to make use of a lookup table:

    Surface rendering of multiple objects
    http://www.vtk.org/pipermail/vtkusers/2011-February/115044.html

Currently, all contours are rendered in the same color.

Thanks,
 Christian


> There are two ways to do this:
> 
> 1) Create two ContourFilters. Use cf1->SetValue(0,val1) and
> cf2->SetValue(0,val2).
>     You will need 2 mappers and actors.
> 2) Create one ContourFilter. Use cf->SetValue(0,val1) and cf->SetValue(1,val2).
>     You will need 1 mapper and actor.
> 
> Both use share the same memory.
> 
> Coloring is easier in case 1).
>   mapper1->SetInput(cf1->GetOutput());
>   mapper1->ScalarVisibilityOff();
>   actor1->SetMapper(mapper1);
>   actor1->GetProperty()->SetDiffuseColor(r,g,b);
>   mapper2->SetInput(cf2->GetOutput());
>   mapper2->ScalarVisibilityOff();
>   actor2->SetMapper(mapper2);
>   actor2->GetProperty()->SetDiffuseColor(r,g,b);
> 
> Case 2 is trickier and involves mucking with lookup tables.
> 
> 
> 
> On Wed, Feb 23, 2011 at 1:16 AM, Thommen Korah <thkorah at hotmail.com> wrote:
> > Hi,
> > I have a pointcloud on which I perform segmentation to extract different
> > structures projecting out of a flat surface (a table for example). The
> > pointcloud is stored in a voxel data structure. I would now like to
> > visualize these segmented regions by creating  isosurfaces using
> > vtkContourFilter for each object. How can I generate multiple surfaces (eg.
> > book and a cup lying on the table) using the same shared data in memory? I
> > would also like to visualize each segmented region in a different color.
> > Thanks.
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