[vtkusers] vtkResliceImageViewer::SetInputData() slow when executed after vtkDICOMImageReader::Update()

[ochampao]

Hi Sankhesh, thanks for the reply.

Please note that I am not doing both in my function i.e. I tried either the
code:

// loads whole dicom series in 2 seconds 
data = reader->GetOutput(); 
resliceImageViewer1->SetInputData(data); 
resliceImageViewer2->SetInputData(data); 
resliceImageViewer3->SetInputData(data); 
reader->Update(); 
// ---------------------------------------------

 -OR-

// Loads whole dicom series in ~22 seconds
data = reader->GetOutput(); 
reader->Update(); 
resliceImageViewer1->SetInputData(data); 
resliceImageViewer2->SetInputData(data); 
resliceImageViewer3->SetInputData(data); 
// ---------------------------------------------

>> As for slowness you see, could you please provide details on the data
>> type and size and how much time is spent in SetInputData? <<

I am loading a CT image volume from a DICOM series (743 slices, ~400MB). If
I place the SetInputData() calls before Update() the whole function
addImage() completes in about 2seconds, whereas if I place SetInputData()
after Update(), the whole function takes ~22seconds. 

When stepping through the code in the slow case, I have noticed that
execution spends about 2seconds on Update(), ~18seconds on the first
SetInputData() and then about 2 seconds on the rest of the code in the
function. So it's the first call to SetInputData() that is slowing down the
execution.

I have also tried the following sequence that calls Update() before
GetOutput(), but it is still equally slow (~22seconds) which I find
counter-intuitive.

// reader->GetOutput() has the data now... Still takes about 22 seconds
reader->Update(); 
data = reader->GetOutput(); 
resliceImageViewer1->SetInputData(data); 
resliceImageViewer2->SetInputData(data); 
resliceImageViewer3->SetInputData(data); 
// ---------------------------------------------

Any suggestions as to why this is happening?

Thanks,
Panos



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