[vtkusers] Cannot make unstructured points isosurface

[Randy Heiland]

Try doing a:

isoMapper->SetTableRange(-.006,.002)

--Randy

On Nov 5, 10:36pm, Chris Scharver wrote:
> Subject: Re: [vtkusers] Cannot make unstructured points isosurface
> At 6:26 PM +0530 11/02/2002, Prabhu Ramachandran wrote:
> >From what I understand you are simply assigning a bunch of points as
> >vertices into an Unstructured grid.  This will not result in a volume.
> >All your data will contain is a bunch of points.  Hence contouring the
> >data will not produce anything.  If you need to contour the data you
> >need to specify volumes which means you need to know the topology.  If
> >that is hard to get in your case try investigating these classes:
> >
> > vtkShepardMethod
> > vtkGaussianSplatter
> > vtkProbeFilter
>
> The vtkShepardMethod did the trick! It did exactly what I needed by
determining the topology based on the points read from the dataset. It
resampled onto a grid with different bounds than the original dataset, but that
should be okay. Thanks tremendously!
>
> Now that I have the surface, I still have to determine why resulting contours
are always red... I only have two contours, but their colors should be based on
the scalar values used to make the surfaces. I tried setting a color lookup
table, but I always end up with the same color for both surfaces.
>
>   vtkContourFilter* iso = vtkContourFilter::New();
>   iso->SetInput(shepard->GetOutput());
>   iso->SetValue(0, -0.006f);
>   iso->SetValue(1, 0.002f);
>   iso->ComputeScalarsOn();
>   iso->UseScalarTree();
>   vtkLookupTable* lut = vtkLookupTable::New();
>   lut->SetNumberOfColors(256);
>   lut->SetTableRange(shepard->GetOutput()->GetScalarRange());
>   lut->Build();
>   vtkPolyDataMapper* isoMapper = vtkPolyDataMapper::New();
>   isoMapper->SetInput(iso->GetOutput());
>   isoMapper->SetLookupTable(lut);
>   isoMapper->SetColorModeToMapScalars();
>   isoMapper->SetScalarRange(shepard->GetOutput()->GetScalarRange());
>   isoMapper->ScalarVisibilityOn();
>   vtkActor* isoActor = vtkActor::New();
>   isoActor->SetMapper(isoMapper);
>   isoActor->GetProperty()->SetOpacity(0.5f);
>
> The scalar data is obviously there since the contours are built correctly.
The scalars are 'small', but shouldn't the SetTableRange() and SetScalarRange()
methods account for that?
>
> Chris
> --
> Chris Scharver
> Electronic Visualization Laboratory
> The University of Illinois at Chicago
> Ph: 312-996-3002   FAX: 312-413-7585
> <http://www.evl.uic.edu/scharver/>
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>-- End of excerpt from Chris Scharver