[vtkusers] Vol.cxx example + vtkImageWriter + vtkImageReader

[Paul McGuinness]

Mathieu,

The reason why I am interested in using vtkImageReader/Writer is to create
data files like the data files headsq/quarter.* such I can use them in
data parallelism. I have tried your method below but the data from one
file 'voldata.vtk' cannot be divided among multiple processors to my
knowledge. Do you know how I can create data files like headsq/quarter?

This is what I am trying to do exactly:
Use vtkImageWriter to write a sphere (or any object) of a specific
size to mulitple files like the files of headsq/quarter.*

Then use a data parallelism program similar to that of ParallelIso.cxx to
read in these files, and measure the time difference between this
parallel program and a similar serial program.

Use the vtkImageWriter again to write the same object of a different size,
and do the whole procedure again.

I hope to get a graphs of data size, number of processors, and time.

Paul



On Wed, 23 Jul 2003, Mathieu Malaterre wrote:

> Paul,
> 	Is there any particular reason why you are using vtkImageReader/Writer ?
>
> Try this instead:
>
> <snip>
> //------------------ Write Data ---------------------------
> //vtkImageWriter *writer =   vtkImageWriter::New();
> vtkStructuredPointsWriter *writer = vtkStructuredPointsWriter::New();
>     writer->SetInput(vol);
>     writer->SetFileName("voldata.vtk");
>     writer->Write();
>
> //----------------- Read Data ---------------------------
> //vtkImageReader *reader  = vtkImageReader::New();
> vtkStructuredPointsReader *reader = vtkStructuredPointsReader::New();
> //   reader->SetDataExtent(0,25, 0, 25, 0, 25);
>     reader->SetFileName("voldata.vtk");
> //   reader->SetDataSpacing(sp, sp, sp);
> //   reader->SetDataOrigin(-0.5,-0.5,-0.5);
> <snip>
>
> HTH
> mathieu
>
> Paul McGuinness wrote:
> > Hi vtk users,
> >
> > I am creating a sphere using vtkImageData and then using vtkContourFilter.
> > This is the simple example Vol.cxx that can be found from the vtk website.
> > The problem I am having is to write the vtkImageData using vtkImageWriter
> > to files, and then reading these files back using vtkImageReader and then
> > contouring the data. I don't obtain the sphere I originally got but a
> > cubic shape that looks like a sponge.
> > Can someone please help me understand what I am doing wrong and how I can
> > fix this.
> > I have attached the code below so you can see what I am talking about.
> >
> > Many thanks,
> > Paul
> >
> >
> > #include "vtkImageWriter.h"
> > #include "vtkImageReader.h"
> > #include "vtkPointData.h"
> > #include "vtkRenderer.h"
> > #include "vtkRenderWindow.h"
> > #include "vtkRenderWindowInteractor.h"
> > #include "vtkStructuredPoints.h"
> > #include "vtkFloatArray.h"
> > #include "vtkContourFilter.h"
> > #include "vtkPolyDataMapper.h"
> > #include "vtkActor.h"
> > #include "vtkImageCast.h"
> >
> > main ()
> > {
> >
> >   float sp, z, y, x, s;
> > int i, j, k,  kOffset, jOffset, offset,h;
> >
> >   vtkImageData *vol = vtkImageData::New();
> >   vol->SetDimensions(26,26,26);
> >   vol->SetOrigin(-0.5,-0.5,-0.5);
> >   sp =1.0/25.0;
> >   vol->SetSpacing(sp,sp,sp);
> >
> >   vtkFloatArray *scalars =vtkFloatArray::New();
> >                      for(k=0;k<26;k++)
> >                      {
> >                      z = -0.5 + k*sp;
> >                      kOffset = k*26*26;
> >
> >                      for(j=0; j<26; j++)
> >                      {
> >                      y = -0.5 +j*sp;
> >                      jOffset = j*26;
> >
> >                      for(i=0;i<26;i++)
> >                      {
> >                      x = -0.5 + i*sp;
> >                      s = x*x + y*y + z*z - (0.4*0.4);
> >                      offset = i + jOffset + kOffset;
> >                      scalars->InsertTuple1(offset,s);
> >                      }
> >                      }
> >                      }
> >
> >   vol->GetPointData()->SetScalars(scalars);
> >
> > //------------------ Write Data ---------------------------
> > vtkImageWriter *writer =   vtkImageWriter::New();
> >   writer->SetInput(vol);
> >   writer->SetFilePrefix("voldata");
> >   writer->Write();
> >
> > //----------------- Read Data ---------------------------
> > vtkImageReader *reader  = vtkImageReader::New();
> >    reader->SetDataExtent(0,25, 0, 25, 0, 25);
> >    reader->SetFilePrefix("voldata");
> >    reader->SetDataSpacing(sp, sp, sp);
> >    reader->SetDataOrigin(-0.5,-0.5,-0.5);
> >
> >
> >
> >   vtkContourFilter *contour = vtkContourFilter::New();
> > //    contour->SetInput(vol);            //original
> >       contour->SetInput(reader->GetOutput());
> >       contour->SetValue(0,0);
> >
> >   vtkPolyDataMapper *volMapper = vtkPolyDataMapper::New();
> >       volMapper->SetInput(contour->GetOutput());
> >       volMapper->ScalarVisibilityOff();
> >   vtkActor *volActor = vtkActor::New();
> >       volActor->SetMapper(volMapper);
> >
> >
> >
> >   vtkRenderer *renderer = vtkRenderer::New();
> >   vtkRenderWindow *renWin = vtkRenderWindow::New();
> >     renWin->AddRenderer(renderer);
> >   vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
> >     iren->SetRenderWindow(renWin);
> >
> >
> >   renderer->AddActor(volActor);
> >       renderer->SetBackground(1,1,1);
> >   renWin->SetSize(200,200);
> >
> >   // interact with data
> >
> >   renWin->Render();
> >   iren->Start();
> >
> >   // Clean up
> >   renderer->Delete();
> >   renWin->Delete();
> >   iren->Delete();
> >   vol->Delete();
> >   scalars->Delete();
> >   contour->Delete();
> >   volMapper->Delete();
> >   volActor->Delete();
> > }
> >
> >
> >
> >
> > _______________________________________________
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>
>
> --
> Mathieu Malaterre
> CREATIS
> 28 Avenue du Doyen LEPINE
> B.P. Lyon-Montchat
> 69394 Lyon Cedex 03
> http://www.creatis.insa-lyon.fr/~malaterre/
>
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