[vtk-developers] Fwd: About constructing a 3D geographical surface

[Soeren Gebbert]

Hi John,
i dont know java so i can only provide some C++ code snips.
But i guess you can do something like this:

double x, y, z, value;
vtkIdList *ids = vtkIdList::New();
vtkPoints *points = vtkPoints::New();
vtkDoubleArray *values = vtkDoubleArray::New();
values->SetNumberOfTuples(NumberOfPointsInDataset);
values->SetNumberOfComponents(1);
values->SetName("resistivity");

for(i = 0; i < NumberOfPointsInDataset; i++)
{
  // Read your data into x, y and z coordiantes
  points->InsertPoint(i, x, y, z);

  //Read your resistivity values
  values->InsertValue(i, value);

  //Create point ids for the cells
  ids->InsertNextId(i);
}

// Build PolyData
vtkPolyData *poly = vtkPolyData::New();
poly->Allocate(NumberOfPointsInDataset);
poly->SetPoints(points);
points->Delete();
poly->GetPointData()->SetScalars(values);
values->Delete();

//Now build the cells. You can build triangles if you know the order
//of your points. If you dont know the order than just create a PolyVertex
cell to render the points in VTK
//use the delaunay triangulator: to triangluate the data

poly->InsertNextCell(VTK_POLY_VERTEX, ids);
ids->Delete();
poly->Sqeeze();

//Now use the delaunay triangulator to triangulate the poly data set
vtkDelaunay2d ....

//The code is untested and without any warranty :)

//END

References:
http://www.vtk.org/doc/release/5.0/html/a01872.html
http://www.vtk.org/doc/release/5.0/html/a01335.html
http://www.vtk.org/doc/release/5.0/html/a01867.html
http://www.vtk.org/doc/release/5.0/html/a01322.html
http://www.vtk.org/doc/release/5.0/html/a01880.html

Best regards
Soeren

2007/10/11, John Ownsoul <mongwarrior at yahoo.com>:
>
>
> Hi Soeran;
>
> Thanks for your attention and help. I can write my own program to map the
> geographical data to java. But, what must i do after than getting the
> values
> and coordinates? Could you send me a sample code or a reference about
> this?
> Thanks again; (I want to use only java and vtk)
>
> Best regards;
>
> John Ownsoul
>
>
>
>
>
>
>
>
> Soeren Gebbert-2 wrote:
> >
> > Hi John,
> > just an idea. If you have geographical data which you want to visualize
> > with
> > vtk
> > than try the combination of the gis grass and paraview. There are many
> > options
> > in grass to get your x,y,z ascii data into it. You can process the data
> > there and export it with the grass module r.out.vtk into the vtk format
> to
> > visualize
> > the data with paraview, visit or mayavi.
> >
> > Or you can build in java a poly dataset with x,y,z point coordinates
> > connected with triangles to
> > each other and store the resistivity values in an point data double
> array.
> > If you have
> > an ordered point set the triangulation should be no problem.
> > AFAIC you have to import the data with your own program. There is no
> > x,y,z,value import module in vtk. But im not sure.
> >
> > Best regards
> > soeren
> >
> > Link to grass:
> > grass.itc.it
> >
> > Link to some grass/vtk modules and related stuff:
> > www-pool.math.tu-berlin.de/~soeren/grass/modules<
> http://www-pool.math.tu-berlin.de/%7Esoeren/grass/modules>
> >
> > 2007/10/11, John Ownsoul <mongwarrior at yahoo.com>:
> >>
> >>
> >> Dear Fellows;
> >>
> >> I have some data about a geographical surface, and i want to show an
> >> image
> >> in VTK (with Java).
> >> But i am a beginner, so i don't know the syntax very well. I practice
> >> with
> >> VTK, but i don't know the file operations. Could you help me to
> construct
> >> the file and show the image in vtk??
> >>
> >> I use these datas at the below:
> >>
> >> x(m)   y(m)   z(m)    resistivity value(ohm.m)
> >> 2        1    -1,406           204,934
> >> 3        1    -1,406           108,021
> >> 4        1    -1,406             62,275
> >> 5        1    -1,406             47,608
> >>                     ...
> >>
> >>
> >> Thanks for everything...
> >>
> >> --
> >> View this message in context:
> >>
> http://www.nabble.com/About-constructing-a-3D-geographical-surface-tf4605431.html#a13150408
> >> Sent from the VTK - Dev mailing list archive at Nabble.com.
> >>
> >> _______________________________________________
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> >> vtk-developers at vtk.org
> >> http://www.vtk.org/mailman/listinfo/vtk-developers
> >>
> >
> > _______________________________________________
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> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/About-constructing-a-3D-geographical-surface-tf4605431.html#a13152207
> Sent from the VTK - Dev mailing list archive at Nabble.com.
>
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