Complex data, Cube data

[Arnold Rots]

STC is not a specific document format.  There is a model behind it.
STC-S and STC-X are specific implementations.  Because the XML
implementation is crucial, it is included in the PR.

But, in order to clarify the model aspects, I created a document that
highlights those specifically.

	http://hea-www.harvard.edu/~arots/nvometa/v1.30/STC-Model.pdf

I would recommend navigating the document through the bookmarks, first
closing all trees from the bottom up.  That may clarify the structure of
the model and the relations between the various components.

  - Arnold

Doug Tody wrote:
> Hi Arnold -
> 
> On Mon, 15 May 2006, Arnold Rots wrote:
> > Several months ago I sent some examples of how STC elements would give
> > a proper metadata description of data cubes and how to ask for such a
> > cube using STC metadata.
> > Could that information be merged into what you are doing in this area?
> 
> Possibly.  The chief issues are that a data cube is a fairly constrained
> problem (N-D image matrix plus a WCS) which is already adequately by FITS
> WCS, and FITS and FITS WCS is what is already in use to store, transport,
> access, and analyze cube data.  Anything we use for cube coordinates has
> to either be based on FITS or at least have a clear mapping to FITS WCS to
> provide reasonable support for existing data and software.  The remaining
> issues of describing cube data can already be dealt with by the generic
> dataset metadata (Characterization etc.) being developed with SSA.
> 
> The issue with the use of STC to "ask" for a cube (cutout,
> projection, etc.) is that this is a specific document format
> and we have a parameter-based interface.  The relatively simple,
> implementation-independent parameter-based interface has worked well, and
> we have already demonstrated that this can handle cutouts and reprojections
> for the 2D case.  We should see whether the parameter-based approach can
> be extended to describing an operation on 3-D data before we consider
> alternative approaches such as document or language-based.
> 
> 	- Doug
> 
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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 head.cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
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