[vtkusers] Centering image display

[TJ Wilkinson]

I am displaying an image volume via an Actor2D, Mapper, Imager, and
ImageWindow. The data appears in the lower left corner of the imager.  How
can I get the image to have its center at the center of the imager?  I
know I can reset the Actor2D's PositionCoordinate, but is there not a
better way to do this?  Is there somewhere where I can reset the origin of
the data so that it is at the center of a slice rather than in the corner?

Also, when I change the resampling factor, the ZSlice of the mapper
remains constant though the underlying data changes as it moves through
it.  I would like to keep the displayed slice constant as I change the
resampling factors.  Any suggestions on the best way to do this?

Thanks.

Todd