Complex data, Cube data

[Doug Tody]

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