[vtkusers] GetOrientation()

[David Gobbi]

Hi Sean,

I agree with you 100%, but I would go even farther.  The vtkDataObject
supports a vtkFieldData that more-or-less allows you to put whatever data
you want inside of the object.  It would be great if there was an
"InformationData" or some such associated with the object that
carried information about how to interpret the data.  A vtkFieldData
object could be used to store the information.

For example, if you wanted to associate an "Orientation" with a
vtkImageData, you could add a 3x3 data array named "Orientation" to the
InformationData that held the orientation.  A filter would be able to
read and modify the Orientation info as desired in the
ExecuteInformation() method.

This information would be exactly as you say: it would be "metadata"
that could be stored in the files just like the image extent, spacing,
etc. are currently stored in the files.

 - David


On Tue, 17 Aug 2004, Sean McInerney wrote:

> It might be a nice extension to the vtkImageData or vtkStructuredPoints
> classes to include an RAS permutation matrix or, at least, to make some
> provision for axis labeling. This metadata could also be an extension to
> the VTK image file format(s). This should be easy to add without
> breaking backwards compatibility (except probably binary) and with
> minimal memory overhead. It seems like such a basic part of imaging work
> that it need not be application specific. Seems like a good candidate
> for a library API ... like VTK. Doing this right within the library
> would be a real boon.
>
> -Sean
>
> David Gobbi wrote:
> > Hi Pallavi,
> >
> > There is no "orientation" for vtkImageData.  The data is always arranged
> > according to an x,y,z data coordinate grid: column number increases with
> > x, row number increases with y, slice number increases with z.  (Unless
> > spacing is negative, in which case col number decreases with x etc)
> >
> >  - David
> >
> > On Tue, 17 Aug 2004, Pallavi Joshi wrote:
> >
> >
> >>Hi,
> >>Is it possible to get the orientation of a grid or a vtkImageData ?
> >>
> >>-------------------------------------------------------------------
> >>Pallavi Joshi
> >>Graduate Student
> >>Medical Image Processing Lab
> >>
>