[vtkusers] Create Structured Point Set?

[Bryn Lloyd]

You need cells and data on the cells (e.g. voxels, tetrahedra or 
something) for contouring.

If your points are dense you could generate an image with values that 
correspond to distance to clostest point. Then contour this image.

Else use delaunay and extract surface from it...




David Doria wrote:
> The data in the vtp is just a set of points (vertices). I wanted to get 
> a surface from the points.
> 
> Here's what I've tried:
> 
> 
>     vtkSmartPointer<vtkXMLPolyDataReader> reader = 
> vtkSmartPointer<vtkXMLPolyDataReader>::New();
>     reader->SetFileName(InputFile.c_str());
>     reader->Update();
>     cout << "NumPoints: " << reader->GetOutput()->GetNumberOfPoints() << 
> endl;
> 
>     vtkSmartPointer<vtkContourFilter> CF = 
> vtkSmartPointer<vtkContourFilter>::New();
>     //CF->SetValue(0,128);
>     double range[2];
>     range[0] = 0;
>     range[1] = 1000;
>     CF->GenerateValues(0, range);
>     CF->SetInputConnection(reader->GetOutputPort());
>     CF->Update();
>    
>     vtkSmartPointer<vtkXMLPolyDataWriter> writer = 
> vtkSmartPointer<vtkXMLPolyDataWriter>::New();
>     writer->SetInputConnection(CF->GetOutputPort());
>     writer->SetFileName(OutputFile.c_str());
>     writer->Update() ;
> 
> but it just makes an empty file. Where have I gone wrong?
> 
> Thanks,
> 
> David
> 
> 
> On Wed, Mar 4, 2009 at 10:00 AM, Bryn Lloyd <blloyd at vision.ee.ethz.ch 
> <mailto:blloyd at vision.ee.ethz.ch>> wrote:
> 
>     Is your data a surface? Is there data associated with the polydata?
> 
>     What do you expect marching cubes to give you? (lines?)
> 
> 
>     You could use vtkContourFilter, it works on any kind of vtkDataSet,
>     i.e. polydata...
> 
>     http://www.vtk.org/doc/nightly/html/classvtkContourFilter.html
> 
>     --Bryn
> 
> 
> 
> 
>     David Doria wrote:
> 
>         I am reading in a vtp file and then trying to run the
>         vtkMarchingCubes filter. It says the input is of type
>         vtkPolyData, but a vtkImageData is required.
> 
>         I tried to use vtkMarchingContourFilter and it says no data to
>         contour.
> 
>         It makes sense that the points should be on a structured grid,
>         but how do I create one?
> 
>         Thanks,
> 
>         David
> 
> 
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> 
>     -- 
>     -------------------------------------------------
>     Bryn Lloyd
>     Computer Vision Laboratory
>     ETH Zürich, Sternwartstrasse 7
>     CH - 8092 Zürich, Switzerland
>     Tel: +41 44 63 26668
>     Fax: +41 44 63 21199
>     -------------------------------------------------
> 
> 


-- 
-------------------------------------------------
Bryn Lloyd
Computer Vision Laboratory
ETH Zürich, Sternwartstrasse 7
CH - 8092 Zürich, Switzerland
Tel: +41 44 63 26668
Fax: +41 44 63 21199
-------------------------------------------------