[vtkusers] to pipeline or not to pipeline, that is the question

[Nico Vermaas]

Hi,

There may be a bug in my understanding of VTK, can somebody enlighten me?

I have build a reader (fitsReader) that gives back a vtkImageData.

It works fine when I define a new vtkImageData (as a member) and (deep)copy the scalars from the reader's result to this new vtkImageData. Like this:

vtkImageData *dataFits = vtkImageData::New();
dataFits=this->fitsReader->GetOutput();
this->myImageData->GetPointData()->DeepCopy(dataFits->GetPointData());
dataFits->Delete();
mapper->SetInput(this->myImageData);
etc...

It also works when I insert a vtkExtractVOI in the pipeline before the Mapper.

But... when I just connect my reader's output to that same new vtkImageData then I do not get any data, like this: 
 
myImageData=fitsReader->GetOutput(); 

Also....
When I do use the 'deepcopy' solution (I get data in myImageData then) and when I then insert a vtkShiftScale into the pipeline (to go from floats to unsigned chars) I lose my data again. Like this:

myImageData->Update(); 
myShiftedScaledData->SetInput(myImageData);
myShiftedScaledData->SetShift(-range[0]);
myShiftedScaledData->SetScale(255./(range[1]-range[0]));
myShiftedScaledData->SetOutputScalarTypeToUnsignedChar();

And this gives an error then ('pixel not in memory'):
value=(float*) myShiftedScaledData->GetOutput()->GetScalarPointer(x,y,z);

Ergo:
I have the feeling that I forget something crucial.
q: is that deepcopy necisary or a dumb solution?
q: should that 'myImageData=fitsReader->GetOutput()' work? (should myImageData contain the scalar data?)
q: does anybody see anything wrong?

Some insight would be much appreciated, Thanks,

Nico 
 



====================================================
Nico Vermaas
ASTRON - Westerbork Synthesis Radio Telescope
Schattenberg 1 - 9433 TA Zwiggelte - The Netherlands

tel: +31 593 598710                 
vermaas at astron.nl 
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