[vtkusers] Why don't reader origin, spacing, extent propogate?

[TJ Wilkinson]

I've been working with vtkImageReader, vtkImageData (of course), and
vtkImageReslice quite a bit, and I'm curious as to why I would care to set
the origin and spacing of the ImageReader object when those values are not
passed along to either the output in the form of ImageData settings or to
the next filter, in terms of Reslice settings.  If anyone has any insight
as to why, I'd love to understand.

Thanks all.

Sincerely,

Todd