[vtkusers] Reading ITK Deformation Field in VTK

[Luis Ibanez]

Hi Sajendra,


a) From what type of ITK Deformable registration did you
    generate this deformation field ?

    (e.g. Demons ?, FEM ?, BSplines ?)


b) If it was from using BSplines,
    did you used a Bulk transform ?


c) The points that you are transforming, are they located
    in the coordinate system of the Fixed image ?
    and are you trying to map them to the coordinate
    system of the moving image ?


d) What is your frame of reference for determining that
    the mapped points are wrong ?  have you loaded one of
    the images into ParaView ? Does this image has an origin
    different from Zero ?


e) What specific version of ParaView are you using ?


    Please let us know,


       Luis


----------------
Sajendra N wrote:
> 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
>