[vtkusers] Exception on vtkImageCacheFilter after modifying the pipeline

[Emiliano Beronich]

Hi all,

I have a pipeline formed by a vtkImageReader2, a vtkImageResample, a
vtkMapToColors and a vtkImageCache, connected in this order to show the
slices of a 3D image.
This code works well while I change the ZSlice parameter of the
vtkImageMapper. But when I modify the pipeline, an exception is thrown.

Reviewing the code of method UpdateData of vtkImageCache, I found that
the algorithm verifies if the pipeline is still valid. If not, it
deletes every image generated previous to the time of pipeline. The
images are deleted but the array Data[i] is not assigned NULL. After
that an exception is thrown in line 148.
       ext = this->Data[i]->GetExtent();

I found a solution to my problem adding the following line to 
vtkImageCacheFilter.cxx version 1.19

136:    if (this->Data[i] && this->Times[i] < pmt)
137:      {
138:      this->Data[i]->Delete();
139:      this->Times[i] = 0;
140:      this->Data[i] = NULL;        // added line
141:      }

Is this a bug? am I doing something wrong o missing something? is it a
known issue?
I made a simple test program to show the exception.

Thanks,
Emiliano



//---------------------------------------------------------------------------


#include "vtkImageReader2.h"
#include "vtkImageResample.h"
#include "vtkImageMapToColors.h"
#include "vtkImageMapper.h"
#include "vtkActor2D.h"
#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkLookupTable.h"
#include "vtkImageData.h"
#include "vtkImageCacheFilter.h"
#include "vtkPointData.h"
#include "vtkRenderWindowInteractor.h"

int main(int argc, char* argv[])
{

   vtkImageReader2 * reader = vtkImageReader2::New();
     reader->ReleaseDataFlagOff();
     reader->SetDataByteOrderToLittleEndian();
     reader->SetDataExtent(0, 63, 0, 63, 1, 93);
     reader->SetDataSpacing(3.2, 3.2, 1.5);
     char VtkDataRoot[256];
     strcpy(VtkDataRoot, getenv("VTK_DATA_ROOT"));
     strcat(VtkDataRoot, "\\Data\\headsq\\quarter");
     reader->SetFilePrefix(VtkDataRoot);
     reader->SetNumberOfScalarComponents(1);
     reader->Update();

   int Zoom = 4;
   vtkImageResample * reslice = vtkImageResample::New();
     reslice->SetInput(reader->GetOutput());
     reslice->SetAxisMagnificationFactor(0,Zoom);
     reslice->SetAxisMagnificationFactor(1,Zoom);

   float range[2];
   reader->GetOutput()->GetPointData()->GetScalars()->GetRange(range);
   vtkLookupTable *lut = vtkLookupTable::New();
     lut->SetTableRange(range[0], range[1]);
     lut->SetHueRange(0.6667, 0.0);
     lut->Build();

   vtkImageMapToColors *color = vtkImageMapToColors::New();
     color->SetInput(reslice->GetOutput());
     color->SetOutputFormatToRGB();
     color->SetLookupTable(lut);

   vtkImageCacheFilter *cache = vtkImageCacheFilter::New();
     cache->SetCacheSize(90);
     cache->SetInput(color->GetOutput());

   vtkImageMapper *mapper = vtkImageMapper::New();
     mapper->SetInput(cache->GetOutput());
     mapper->SetZSlice(12);
     mapper->SetColorWindow(255);
     mapper->SetColorLevel(127.5);

   vtkActor2D *actor = vtkActor2D::New();
     actor->SetMapper(mapper);

   vtkRenderer *renderer = vtkRenderer::New();
     renderer->AddActor(actor);

   vtkRenderWindow *renderwindow = vtkRenderWindow::New();
     renderwindow->AddRenderer(renderer);
     renderwindow->SetSize(64*Zoom, 64*Zoom);

   renderwindow->Render();
   for(int j=0; j<5; j++){
     for(int i=0; i<90; i++){
       mapper->SetZSlice(i);
       renderwindow->Render();
     }
     //Modify the pipeline after loading images in cache
     reslice->SetAxisMagnificationFactor(0,Zoom-1);
     reslice->SetAxisMagnificationFactor(1,Zoom-1);
     // Next call to UpdateData() of cache will throw an exception
   }

   vtkRenderWindowInteractor *interactor =
vtkRenderWindowInteractor::New();
   renderwindow->SetInteractor(interactor);
   interactor->Initialize();
   interactor->Start();

   interactor->Delete();
   renderwindow->Delete();
   renderer->Delete();
   lut->Delete();
   actor->Delete();
   mapper->Delete();
   cache->Delete();
   color->Delete();
   reslice->Delete();
   reader->Delete();
   return 0;
}
//---------------------------------------------------------------------------