[vtkusers] segmentation fault with vtkImageData and vtkMetaImageReader

[Laurent Mundeleer]

Yes thank you, that's a solution :)
And actually with this I can keep smartPointers.

Best regards,

++
Laurent


On Wed, 2011-06-08 at 17:45 +0200, Jérôme wrote:
> That's much clearer now!
> If your reader and cast filter are not in the same place (focus), 
> the smart pointer has deleted the reader. Now it's sure. The simplest
> work around (but not the fanciest/cutest) would be:
> 
> reader->Update( );
> vtkImagedata* readerOutput =
> vtkImageData::SafeDownCast( reader->GetOutputDataObject( 0, 0 ));
> vtkImageData* myImage = vtkImageData::New( );
> myImage->DeepCopy( readerOutput );
> 
> Then you can use myImage everywhere you want. Don't forget to
> Delete( ) it, since it is not a SmartPointer but a simple New()
> allocation.
> 
> HTH
> Jerome
> 
> 
> 2011/6/8 Laurent Mundeleer <laurent.mundeleer at uclouvain.be>
>         Hi Jerome,
>         Thank you for your answer.
>         
>         The problem is that the reader and the cast are not done at
>         the same
>         place so that's why I have a vtkImageData which is transmitted
>         in
>         another parts of the code.
>         I use a vtkImageData to have some informations such as
>         dimensions,
>         center, etc and because we use other types so we have
>         sometimes to
>         translate from vtkImageData to another image type (custom
>         image types or
>         QImage for instance).
>         
>         I understand I break the pipeline doing this as I have :
>         reader->imageData | break
>         imageData->cast->mapper-> etc
>         instead of : reader->cast->mapper-> etc
>         But if I want to keep the pipeline complete, I have to
>         transmit a
>         vtkAlgorithm pointer which is less usable outside of vtk, and
>         actually I
>         don't need the beginning of the pipeline, I have enough with
>         the
>         vtkImageData.
>         
>         Actually if I delete the reader pointer I have the same
>         problem, so that
>         means using the setInput() method as I do involves somewhere a
>         call to
>         myVtkImageData->GetProducerPort() which is became null...
>         
>         That means also I guess I can't use the same reader to read a
>         lot of
>         vtkImageData for instance (which would solve my leak problem),
>         because
>         somewhere it keeps a reference to the reader which has done
>         the import
>         in the vtkImageData.
>         I can't imagine what happen if I read a first vtkImageData,
>         and then a
>         second, and try to display or apply a filter to the first one.
>         
>         Thanks,
>         
>         Laurent
>         
>         
>         On Wed, 2011-06-08 at 16:42 +0200, Jérôme wrote:
>         > Hi,
>         >
>         > You should use
>         cast->SetInputConnection( reader->GetOutputPort( ) );
>         > instead of the old fashion SetInput.
>         > IMHO, the problem is that your smart pointer, for some
>         reasons
>         > (reference count becomes null), decided to deallocate the
>         reader, and
>         > thus the underlying output.
>         >
>         > HTH,
>         > Jerome
>         >
>         > 2011/6/7 Laurent Mundeleer <laurent.mundeleer at uclouvain.be>
>         >         Hi everyone,
>         >         I have a strange problem in reading a MetaImage.
>         >         I have a segmentation fault when I access the
>         vtkImageData,
>         >         but if I use a direct pointer instead of a
>         smartPointer on the
>         >         vtkImageReader it's ok (but I have a memory leak).
>         >
>         >         What am I doing wrong ?
>         >         Here are some code extracts of what is working :
>         >
>         >         // in reader method :
>         >         ...
>         >         vtkImageData *imageData = 0;
>         >         ...
>         >
>         >         vtkMetaImageReader* reader =
>         vtkMetaImageReader::New();
>         >         //add to replace :
>         vtkSmartPointer<vtkMetaImageReader> reader
>         >         = vtkSmartPointer<vtkMetaImageReader>::New();
>         >         // and have no delete at the end of the reading
>         >         ..
>         >         reader->Update();
>         >         ...
>         >         imageData = reader->GetOutput();
>         >
>         >         // no delete on the reader
>         >
>         >         /------------------------------------------
>         >
>         >         // in renderer method :
>         >            vtkSmartPointer<vtkImageCast> castSource
>         >         =vtkSmartPointer<vtkImageCast>::New();
>         >            castSource->SetOutputScalarTypeToUnsignedChar();
>         >            castSource->SetInput(imageData); // seg fault
>         >            castSource->Update();
>         >
>         >         /---------------------------------------------
>         >         // or in unit test :
>         >         vtkImageData*volume = readingMethod();
>         >         ...
>         >         double *origin = volume->GetOrigin(); // seg fault
>         >
>         >
>         >         Thank you for any help,
>         >         Best Regards,
>         >
>         >         ++
>         >         Laurent
>         >
>         >
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