[vtkusers] convert polydata to volume

[Karl]

David and others,

Thanks for the response.  I am moving in the right direction.  I have
implemented the vtkcutter but it only partially meets my needs.

1) I still end up with a polydata (a 2d one) and need to convert it to a 2d
image.
2) The thickened lines produced by vtkTubeFilter are of a poor quality.  It
is speckled with very small black dots and cracks.  I suppose this occurs
where the line segments meet.

Any further suggestions.

Thanks,
KB
-----Original Message-----
From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf
Of David Gobbi
Sent: Saturday, December 19, 2009 12:26 PM
To: vtkusers
Subject: Re: [vtkusers] convert polydata to volume

Hi Karl,

The vtkCutter can generate contours directly from your surface mesh.
It takes a vtkPlane to describe the cut plane for the contours.  I
believe that there is an ImplicitPlane widget that you can use to
control the plane.

If the contour lines look too thin, you can use vtkTubeFilter to
thicken them before feeding them into the mapper.

   David


On Sat, Dec 19, 2009 at 10:04 AM, Karl <bulkmailaddress at gmail.com> wrote:
> Bill,
>
> Thanks for the response.  I have a VRML file with a single object
(triangle
> mesh, normal, colors).  I need to implement something that behaves like
the
> vtkImagePlaneWidget where GetResliceOutput can be used to create an image
> with the (colored) contours from a slice through the polydata.  My thought
> was to sample the polydata into a volume and then directly use the
> vtkImagePlaneWidget.  Any ideas?
>
> Thanks,
> KB
>
> -----Original Message-----
> From: Bill Lorensen [mailto:bill.lorensen at gmail.com]
> Sent: Saturday, December 19, 2009 10:41 AM
> To: bulkmailaddress at gmail.com
> Cc: vtkusers
> Subject: Re: [vtkusers] convert polydata to volume
>
> Karl,
>
> The ProbeFIlter takes each point in its input and samples the source
> the point attributes by interpolating the point position in the
> source.
>
> It cannot convert a polydata into a volume.
>
> Can you explain what your end goal is? What is the ultimate problem
> you are trying to solve? What is contained in the polydata?
>
> Bill
>
> On Sat, Dec 19, 2009 at 2:18 AM, Karl <bulkmailaddress at gmail.com> wrote:
>> Hi,
>> I am attempting to use vtkProbeFilter convert a polydata into a volume
> data
>> set that will have colored lines corresponding to the contours of the
>> polydata.  So far the produced image is always empty.  Can anyone see
>> anything wrong with the following code?  Any help would be appreciated?
>>
>> // polydata to be converted
>> vtkPolyData* polyData = ...
>> double bounds[6];
>> polyData->GetBounds(bounds);
>>
>> // identify sampling locations
>> int samples = 30;
>> vtkImageData* samplingArray = vtkImageData::New();
>> samplingArray->SetNumberOfScalarComponents(3);
>> samplingArray->SetScalarTypeToUnsignedChar();
>>
>
samplingArray->SetSpacing((bounds[1]-bounds[0])/samples,(bounds[3]-bounds[2]
>> )/samples,(bounds[5]-bounds[4])/samples);
>> samplingArray->SetDimensions(samples, samples, samples);
>> samplingArray->SetOrigin( bounds[0], bounds[2], bounds[3] );
>> samplingArray->Update();
>>
>> // sample polydata
>> vtkProbeFilter *probe = vtkProbeFilter::New();
>> probe->SetInput(samplingArray);
>> probe->SetSource(poly);
>>
>> // save results
>> vtkTIFFWriter* tiff = vtkTIFFWriter::New();
>> tiff->SetInputConnection(probe->GetOutputPort());
>> tiff->SetFilePrefix("sampled");
>> tiff->Write();
>>
>>
>> Thanks,
>> KB
>>
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