[Insight-users] VTK to ITK Transform

[Luis Ibanez]

Hi Neilson,


1) ITK and VTK image should be flipped along the "Y" axis,
    not the "X" axis.

    What file format are you using ?

    In order to work consistenty between ITK and VTK you
    should "think" on physical space. That includes to
    be aware of the position and orientation of the
    vtkCamera.  You want to put the vtkCamera in the location
    and orientation of the physician that is looking at the
    images. (a neurosurgeon will be above the patient head
    looking down to the patients' feet, a radiologist will
    be at the patient's feet, looking towards the patient's
    head, .. in both cases the patient will be lying on his
    back on a horizontal table.

    If you are actually developing a medical application
    you probably should use the DICOM default coordinate
    system in order to organize the scene visualization.



2) Transforms in VTK are applied to actors, and they
    *actually* move the image in space. Transforms in ITK
    map from the original space to the space of the image,
    so, most of the time, the ITK transform that you use
    in a resample image filter should be the inverse of
    the VTK transform that you want for visualization
    purposes.



   Regards,



      Luis



----------------------
Neilson Mackay wrote:
> Hello,
> 
> I am having some difficulty using the same transform in VTK and ITK.   I 
> have two problems:
>     1.  Images read in VTK and ITK are flipped along the 'X' axis.
>     2.  The transforms I use to translate a image in VTK doesn't seem 
> to  position the image in the same position in ITK.
> 
> Has anyone else ran into similar difficulties?  I assume the 2nd  
> problem of mine has something to do with how rotation is applied in  VTK 
> vs ITK.
> 
> As a reference I am using "vtkTransform" in vtk and  "Euler3DTransform" 
> in ITK.  Also, the images I am comparing are of  different spacing.  To 
> confirm where Image A is on image B in itk I  am using the 
> "ResampleImageFilter".
> 
> I could go on with more code if it would help shed some light.
> 
> I am open to any suggestion,
> Cheers,
> Neilson
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