[vtkusers] Displaying Oblique Orientation Image Correctly?

[David Gobbi]

Hi Constantine,

Dealing with oriented images in VTK is not easy.  I usually do a
combination of things.  First, I use vtkImageReslice to extract slices
in the orientation that I need, and then use vtkImageActor with a
transform that ensures they are displayed in the right coordinate
system (I match the VTK world coordinate system with the DICOM
patient coordinate system).  The vtkImageReslice class has a
SetInformationInput() method that can be used to reslice one image to
match another in terms of grid size while applying a transform, this
can be used before blending images or checkerboarding them.

I'm writing some more advanced image display classes for VTK that
should help to simplify the issue.  You can read about them here:
http://www.vtk.org/Wiki/VTK/Image_Rendering_Classes, comments are
welcome.

 - David


On Wed, Feb 16, 2011 at 7:56 AM, Constantine Zakkaroff <mnkz at leeds.ac.uk> wrote:
> Hello ALL.
>
> Can someone please help me out with a clarification?
>
> Say, a volume with double-oblique orientation (short-axis cardiac stack)
> from DICOM is loaded. Then itk::ImageToVTKImageFilter<SomeImageType> is used
> to obtain vtkImageData. So far so good.
>
> Now, since vtkImageData has no knowledge of the original oblique orientation
> of the image as it exists in itk::OrientedImage<TPix, TDim>, when displaying
> the resulting vtkImageData in vtkImageViewer2 none of the voxels appear in
> their correct physical location apart from the voxel at vtkImageData origin.
> This is (obviously) because advancing along the grid of our vtkImageData has
> a different/incorrect meaning without the original double-oblique
> orientation; the grid of vtkImageData does not correspond to the original
> physical space of the image.
>
> I realise one way to display an image like that is to use vtkImageActor with
> an appropriate transform set to it, but this is not suitable when
> visualising registration outcomes with vtkImageCheckerboard.
>
> What is the process of displaying such images correctly? Is this is the case
> where one would use vtkGridTransform? Or is there something else I'm
> missing?
>
> Many thanks,
> Constantine
>
>
>
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