[vtkusers] vtkImageReslice question

[Andi2008]

The program crashes in vtkImageShiftScale in the vtkImageShiftScaleExecute
method. Because it wants to loop through the output which isn't allocated.
To get such an error i have to drive my program to the limit and load a
massive amout of data like 1.3 to 1.5 Gb. I run my program in 32bit. The
point is that my program provide such a possibility and i think i will limit
it and maybe switch to 64bit.
But i have another question about the errorhandling. Isn't it possible to
prevent this crashes by adding an observer which handles
vtkCommand::ErrorEvent?
I already wrote a class which is inherite from vtkCommand and in there i
only override the Execute methode like:

 void CImageVtkErrorObserver::Execute(vtkObject *caller, unsigned long
nEvent, void* pData) 
{
	switch (nEvent)
      {
				case vtkCommand::ErrorEvent:
					{				
					   //errorhandling
                                          int nBreakpoint =0;
					}
					break;
				case vtkCommand::WarningEvent:
					{
					//handle warnings 
                                        int nBreakpoint =0; 
					}
					break;
	}
}

Im this methode i could stop the reslicing. I added this observer to the
vtkImageScale and also vtkImageReslice objects:
        m_pErrorObserver = CImageVtkErrorObserver::New();  //class inherite
from vtkCommand
	m_vtkShiftscale = vtkImageShiftScale::New();
	m_vtkShiftscale->SetInput(volumedata->getImageData());
	m_vtkShiftscale->SetShift(0.5*m_nWindow - m_nLevel);
	m_vtkShiftscale->SetScale(255.0/m_nWindow);
	m_vtkShiftscale->ClampOverflowOn();
	m_vtkShiftscale->SetOutputScalarTypeToUnsignedChar();
	m_vtkShiftscale->AddObserver(vtkCommand::ErrorEvent, m_pErrorObserver,
1.0);
	m_vtkShiftscale->AddObserver(vtkCommand::WarningEvent, m_pErrorObserver,
1.0);	

	m_vtkImageReslicer = vtkImageReslice::New();
	m_vtkImageReslicer->SetInput(m_vtkShiftscale->GetOutput());
	m_vtkImageReslicer->SetOutputDimensionality(2);
	m_vtkImageReslicer->SetInterpolationModeToCubic();
	m_vtkImageReslicer->SetOutputSpacing(spacing);
	m_vtkImageReslicer->AutoCropOutputOn();
 	m_vtkImageReslicer->AddObserver(vtkCommand::ErrorEvent, m_pErrorObserver,
1.0);
	m_vtkImageReslicer->AddObserver(vtkCommand::WarningEvent, m_pErrorObserver,
1.0);


But still the OutputWindow appears and it doesn't step into the execute
methode. Did I forgot something? 

Andi



David Gobbi-3 wrote:
> 
> Hi Andi,
> 
> A memory allocation error on a 10MB allocation sounds suspicious.  You
> might have to dig deeper to see exactly why the call is failing,
> because it probably isn't an actual "out of memory" problem.  If you
> run inside a debugger, can you get a stack trace for when the "new"
> call fails?
> 
> When I'm doing oblique slicing, I usually call UpdateWholeExtent() on
> the filter before the reslice (in your case, this is the shiftscale).
> This is necessary because, as you have seen, oblique slicing generates
> large UpdateExtents that are always changing.  This won't help the
> memory issue, but it will make your app run faster.
> 
>    David
> 
> 
> On Fri, Dec 18, 2009 at 4:29 AM, Andi2008 <mail-andi at web.de> wrote:
>>
>> Hi,
>>
>> thank you for the answer. I use one vtkImageReslice for one single view
>> and
>> i extract always a single slice. I agree with you that the output extent
>> of
>> axial/sagittal and coronal views is always the same and I checked my code
>> for this and found out my program doesnt crashes when I just display the
>> three orthogonal views.
>> But I implemented also the ablility to reslice in any possible direction
>> and
>> angles. In this case it happens what you descibe. In every time Render is
>> called the outputextent is recalculated because it is always different. I
>> implemented the pipeline like:
>>
>>        m_vtkShiftscale = vtkImageShiftScale::New();
>>        m_vtkShiftscale->SetInput(volumedata->getImageData()); //<--
>> vtkImageData
>> with the volume
>>        m_vtkShiftscale->SetShift(0.5*m_nWindow - m_nLevel);
>>        m_vtkShiftscale->SetScale(255.0/m_nWindow);
>>        m_vtkShiftscale->ClampOverflowOn();
>>        m_vtkShiftscale->SetOutputScalarTypeToUnsignedChar();
>>
>>        m_vtkImageReslicer = vtkImageReslice::New();
>>        m_vtkImageReslicer->SetInput(m_vtkShiftscale->GetOutput());
>>        m_vtkImageReslicer->SetOutputDimensionality(2);
>>        m_vtkImageReslicer->SetInterpolationModeToCubic();
>>        m_vtkImageReslicer->SetOutputSpacing(spacing);
>>        m_vtkImageReslicer->AutoCropOutputOn();
>>        m_vtkImageReslicer->Update();
>>
>> I perform the reslicing by calculating a new transformationmatrix by
>> given
>> centerpoint and angles around x,y and z axis. I call the SetResliceAxis
>> method to set the new transformationmatrix the call Update to perform the
>> reslice. During the update it crashes if there is not enough memory. The
>> amount of needed memory is not that much(usually around 10mb) but it can
>> happend that it can't be allocated. I know that the outpuextent is not
>> exact. Therefore I call the imageshiftscale before the reslice. Otherwise
>> i
>> get gray areas in the resultimage in cause of the window/level
>> calculation.
>>
>> How can I prevent this crash?
>> Kind regards
>> Andi
>>
>>
>>
>>
>>
>> David Gobbi-3 wrote:
>>>
>>> Check the WholeExtent of the output from reslice.  By default, the
>>> size of the OutputExtent is set to be large enough to fully contain
>>> the transformed input Extent.  Try to imagine a rotated cube inside of
>>> larger enclosing cube.  The volume of the outer cube can be many times
>>> larger than that of the inner cube, especially for rotations of 45
>>> degrees.
>>>
>>> You need to set the OutputExtent of reslice to something reasonable
>>> for your application.  Don't rely on the default output extent.  If
>>> you are doing the reslicing so that you can view individual slices,
>>> then set the output extent to just a single slice.
>>>
>>> I'm not sure whether you are guilty of this, but I've seen several
>>> people who use ImageReslice to rotate the whole volume, and then use
>>> VOI or ImageClip or ImageActor to extract slices in the three
>>> directions (axial, sagittal, coronal).  This is bad design, because
>>> one of two things will happen: 1) on each render, each view requests a
>>> different update extent, which forces reslice to re-execute on each
>>> and every render. 2) if reslice.UpdateWholeExtent() is called, the
>>> unnecessary re-executions don't occur, but a lot of memory is used.
>>> The proper way to use reslice is to use one reslice per view
>>> orientation.
>>>
>>>    David
>>>
>>>
>>> On Thu, Dec 17, 2009 at 9:00 AM, Andreas Brüning <mail-andi at web.de>
>>> wrote:
>>>> Hello,
>>>>
>>>> ich have a problem when i use vtkImageReslice on a very large volume.
>>>> Sometimes when i don't have enough memory for the reslice operation the
>>>> global warningwindow appears. In there is written that vtk is unable to
>>>> allocate an amount of memory. After this my program crashes immediately
>>>> and i would like to catch this before it crashes. Is there a way get a
>>>> notification when there is not enough memory? (maybe a callback
>>>> function)
>>>>
>>>> Thanks in advance
>>>> Andi
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>>
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> 
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> 
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