[vtkusers] extent, spacing and origin propagation problem through filters

[Matei MANCAS]

Hi, all!

    I thought that if first I have a ImageData having some extent, spacing, etc and than if I applay a filter on it, I will keep the same extent and spacing... But it seems to be wrong!

    I have the following example :



  int a,z,e,r,t,y;
  data->VolReader->GetExtent(a,z,e,r,t,y);                                 //here I have the good Z extent (0 100) (VolReader is a vtkImageData)
 
  vtkImageShiftScale *my_shift = vtkImageShiftScale::New();         //a filter  
             my_shift->SetInput(data->VolReader);
             my_shift->SetScale(my_shift->GetScale()/256.0);
             my_shift->SetOutputScalarTypeToUnsignedChar();
 
data->VolReader=my_shift->GetOutput();                                       // I have the same bad results using DeepCopy method...
 
data->VolReader->GetExtent(a,z,e,r,t,y);                                     //here I have a bad Z extent (0 -1)

 my_shift->GetOutput()->GetExtent(a,z,e,r,t,y);                            //here I have a bad Z extent too : (0 -1)
 my_shift->GetInput()->GetExtent(a,z,e,r,t,y);                            //here I have the good Z extent (0 100)




    This problem seems to be common to all vtkImageToImageFilter, so I would really need help on this subject : I would want to apply to a vtkImageData one or more filters before rendering it.

I really thanks you a lot for your help!!!


Matei
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