[vtkusers] Try Again - vtkImageActor shearing distortion

[Dean Inglis]

Hi,

my original post has gone unanswered:
http://public.kitware.com/pipermail/vtkusers/2003-November/021035.html

so in the interim, I have done some more tests.
I constructed the following pipeline to read in a raw 2D
image of signed short data with a header offset and pass the
data through a filter to a vtkImageActor in two separate
renderers/windows:

<intitalize>

  m_reader = vtkImageReader::New();

  m_reader->SetDataScalarTypeToShort();
  m_reader->SetDataByteOrderToLittleEndian();
  m_reader->SetFileDimensionality(2);
  m_reader->FileLowerLeftOff();
  m_reader->SetDataOrigin(0,0,0);
  m_reader->SetHeaderSize(1609);
  m_reader->SetDataSpacing (0.2, 0.2, 1.0);
  m_reader->ReleaseDataFlagOff();

  m_inputImageActor = vtkImageActor::New();
  m_outputImageActor = vtkImageActor::New();

<snip>

<read the data, toggle between tow files with the same extent>

  String fname;
  if(i1ori2)
    {
    fname = "I0021251.m01";
    }
  else
    {
    fname = "I0021251.m02";
    }

  i1ori2 = !i1ori2;

   struct stat statbuf;
   FILE *stream;
   if ((stream = fopen(fname.c_str(), "rb"))
       == NULL)
   {
      return;
   }

  fstat(fileno(stream), &statbuf);
  fclose(stream);

  int extent = static_cast<int>(sqrt((statbuf.st_size - 1609)/2))-1;

  m_reader->SetFileName(fname.c_str());
  m_reader->SetDataExtent(0,extent,0,extent,0,0);
  m_reader->Update();

<snip>

<setup pipeline 1>

  vtkImageMapToWindowLevelColors* m_WLMap =
vtkImageMapToWindowLevelColors::New();
  m_WLMap->ReleaseDataFlagOn();
  m_WLMap->SetInput(m_reader->GetOutput());
  m_WLMap->SetWindow(255);
  m_WLMap->SetLevel(127.5);
  m_WLMap->Update();

  m_inputImageActor->SetInput(m_WLMap->GetOutput());

  m_inputImageActor->VisibilityOn();

  m_inputImageActor->SetDisplayExtent(
m_inputImageActor->GetInput()->GetWholeExtent());
  m_inputImageActor->Modified();

  vtkWindow1->Repaint();  // a Borland vtk renderer, render window and
interactor all in one

  m_WLMap->Delete();

<snip>

<setup pipeline 2>

  vtkImageMapToWindowLevelColors* m_WLMap2 =
vtkImageMapToWindowLevelColors::New();
  m_WLMap2->ReleaseDataFlagOn();
  m_WLMap2->SetInput(m_reader->GetOutput());
  m_WLMap2->SetWindow(255);
  m_WLMap2->SetLevel(127.5);
  m_WLMap2->Update();

  m_outputImageActor->SetInput(m_WLMap2->GetOutput());

  m_outputImageActor->VisibilityOn();

  m_outputImageActor->SetDisplayExtent(
m_outputImageActor->GetInput()->GetWholeExtent());
  m_outputImageActor->Modified();

  vtkWindow2->Repaint();  // a Borland vtk renderer, render window and
interactor all in one

  m_WLMap2->Delete();

<snip>


Ok so far these pipelines execute properly and toggling between different
images
with the same extent is error free.  If I replace one of the
vtkImageMapToWindowLevelColors filters to vtkImageShiftScale or
vtkImageClamp
in either of the pipelines, I get shearing distortion!!!!

Please help!

Dean