[vtkusers] correction of spacing

[Bartosz Wiklak]

I found post (posted in 2003) stating that:

"To truly change the spacing [... for vtkImageData and vtkImageViewer
which is my case ...], you must resample the pixel or voxel data on a
new sampling grid. Take a look at vtkImageResample."

On Mon, Nov 24, 2008 at 11:25 PM, Bartosz Wiklak <bwiklak at gmail.com> wrote:
> Hi, thanks for answear
>
> If I understand, you suggested to use reader->Update() or
> reader->GetOutput()->Update().
> It doesn't work for me, I still can see that spacing is wrong.
>
> I'm not sure, but after some actions UpdateInformation is called automatically.
> Sample code:
>
>  spacing[2] = 1.5;
>
>  reader->GetOutput()->SetSpacing(spacing);
>
>  reader->Update();
>
>  reader->GetOutput()->UpdateInformation();
>
>  reader->GetOutput()->GetSpacing(spacing);
>
>
> or
>
>  spacing[2] = 1.5;
>
>  reader->GetOutput()->SetSpacing(spacing);
>
>  reader->GetOutput()->Update();
>
>  reader->GetOutput()->UpdateInformation();
>
>  reader->GetOutput()->GetSpacing(spacing);
>
> Gives me spacing[2]==1.0
>
>
> What can I do?
>
> Bartek
>
>
> On Mon, Nov 24, 2008 at 7:58 PM, Dominik Szczerba <dominik at itis.ethz.ch> wrote:
>> Haha! - see my recent posts.
>> Try updating the pipeline with the correct spacing.
>>
>> Dominik
>>
>> Bartosz Wiklak wrote:
>>>
>>> Hello,
>>>
>>> I'm using GDCM  ( vtkGDCMImageReader ) to read some MR data.
>>> I switched  SetComputeZSpacing on, set SetZSpacingTolerance to 1e-2
>>> and used IPPSorter.
>>> This is my code:
>>>
>>>  vtkGDCMImageReader *reader = vtkGDCMImageReader::New();
>>>
>>>
>>>
>>>        std::vector<std::string> filenames;
>>>
>>>
>>>
>>>        gdcm::Directory d;
>>>
>>>
>>>
>>>        d.Load( "/home/basiek/Dokumenty/dcms/testGLOWA/1", false );
>>>
>>>
>>>
>>>        filenames = d.GetFilenames();
>>>
>>>        gdcm::IPPSorter s;
>>>
>>>        s.SetComputeZSpacing( true );
>>>
>>>        s.SetZSpacingTolerance( 1e-2 );
>>>
>>>        bool b = s.Sort( filenames );
>>>
>>>        if( !b )
>>>
>>>                {
>>>
>>>                std::cerr << "Failed to sort:" << "s" << std::endl;
>>>
>>>                return 1;
>>>
>>>                }
>>>
>>>
>>>
>>>        std::cout << "Sorting succeeded:" << s.GetZSpacing() << std::endl;
>>>
>>>        //s.Print( std::cout );
>>>
>>>
>>>
>>>        const std::vector<std::string> & sorted = s.GetFilenames();
>>>
>>>
>>>
>>>        vtkStringArray *files = vtkStringArray::New();
>>>
>>>        std::vector< std::string >::const_iterator it = sorted.begin();
>>>
>>>        for( ; it != sorted.end(); ++it)
>>>
>>>        {
>>>
>>>        const std::string &f = *it;
>>>
>>>        files->InsertNextValue( f.c_str() );
>>>
>>>        }
>>>
>>>        reader->SetFileNames( files );
>>>
>>>        reader->Update();
>>>
>>> I'm getting zspacing 1.5 whitch is ok, but in the
>>> reader->GetOutput()->GetSpacing(spacing) I'm getiing spacing[2]==1.0 !
>>>
>>> What am I doing wrong?
>>> I tried to set pixelspacing manually but after
>>> reader->GetOutput()->UpdateInformation() I'm with old, wrong value
>>> again.
>>>
>>> When I make reslice in coronal I have eyes shaped like ellipses. I
>>> tired to set pixelspacing for vtkImageReslice:
>>> reslice->SetOutputSpacing( spacing[0], spacing[1], 1.5 );
>>>
>>> but this also makes no difference regardless
>>> reslice->GetOutput()->UpdateInformation().
>>>
>>> Can someone point me in the right direction?
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>>
>> --
>> Dominik Szczerba, PhD
>> Computational Physics Group
>> IT'IS Foundation
>> http://www.itis.ethz.ch
>>
>