[vtkusers] Reading ITK Deformation Field in VTK

[Sajendra N]

Hi everyone,

After performing a deformable registration using ITK, I saved the
resulting deformation field to disk in MetaImage format using
itkImageFileWriter.
I later read the deformation field from disk into VTK using
vtkMetaImageReader and set that as the input to a vtkGridTransform
which I use to transform points, however the point locations after
transformation are wrong.
If I do everything in ITK (reading the metaimage file, transforming
points), I get the correct transformation.
At least part of the problem was the the "POSITION" tag was not
written in the header, it was written as "OFFSET" instead. I fixed
that manually but I am still having problems.
Is there a further incompatibility in the file formats? I am hoping
someone has done this successfully in the past and had some ideas.
I can provide sample data and code to reproduce the issue, but the
data set might be rather large.

Thank you,
Sajendra

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