[ImageDM] Mapping

[Arnold Rots]

If it's any consolation, I didn't have any trouble getting the document
through you original link.
Using Firefox.

  - Arnold

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Arnold H. Rots                                          Chandra X-ray
Science Center
Smithsonian Astrophysical Observatory                   tel:  +1 617 496
7701
60 Garden Street, MS 67                                      fax:  +1 617
495 7356
Cambridge, MA 02138
arots at cfa.harvard.edu
USA
http://hea-www.harvard.edu/~arots/
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On Mon, Dec 9, 2013 at 3:42 PM, CresitelloDittmar, Mark <
mdittmar at cfa.harvard.edu> wrote:

> All,
>
> I've been wanting to get this out for discussion before we get too close
> to the holidays.
>
> In the hopes of settling the debate about whether or not STC provides the
> capabilities encapsulated in the Mapping object, I have gone through the
> trouble of making a step-by-step transition of Mapping elements to an STC
> based model.
>
> You can find the document in Volute.  I have also posted the link on the
> twiki.
>
> https://volute.googlecode.com/svn/trunk/projects/dm/ImageDM/doc/Mapping-STC.pdf
>
> I'm not sure if this will help or hinder my point in the end, Mapping
> takes a LOT of information about Frames, Axis linkages, Transforms, etc..
> and flattens it to an encapsulation of the FITS WCS serialization (for the
> most part).  Pulling that out gets somewhat complicated, but in my opinion,
> anything not in the diagram would need to be explained in the text.
>
> ImageDM (and other earlier models) simplified STC elements (Frames),
> cutting off the complicated inter-system relations that are in the STC
> objects.  I hope this shows pretty definitively that by NOT simplifying
> them we get the desired capability, but properly modeled and more
> flexible.  I think this scenario provides some important benefits:
>   - uses established IVOA recommendation, so ImageDM can spend its space
> with use-case diagrams rather than re-defining objects
>   - enables the 'intermediate' axis set to be realized as actual axes.
>   - enables scaling of 'Observable' data values
>   - reduces redundant info.  The Mapping object provides partial WCS Frame
> information, presumably the full definitions would have to be stored
> somewhere else.
>   - reduces irrelevant attributes.
>   - provides a consistent framework from which we can generalize for
> general hypercube data and specialize/reuse in the Spectral model to enable
> 'virtual' columns (which are currently not possible).
>
> Please have a look.. hopefully we can have some good discussion over the
> next couple weeks.
> Francois and I had some discussion about this approach back in July.. I'll
> need to dig up those comments and see how they relate to this effort.
>
> Mark
>
>
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