WD-AccessData-1.0-20140312

[Petr Skoda]

>
>> but letters and devise the way how to request multiple ranges => BAND=B,V,R
>
> Some folks don't like list-valued parameters (likewise POL=I,Q,U), but
> it does seem more natural and convenient for the client doesn't it?

At least for scientist who should be tought to use the VO stuff it is the 
most natural way - of course something like [U,B,V] or other formalism 
might be accepted.



>> meters explicitly) - but how the user will know the units of original data?
>
> By a prior queryData and/or getMetadata.  In particular, for most
> advanced image access via accessData, one will need to know the image
> geometry and WCS, which will be returned with getMetadata (which is not
> yet fully defined, and requires more work on the Image data model).

well this returns to philosophy about rectangular circle for SIAP query or 
cutout ....
But I had in mind the BAND units - suppose several X-ray channels (similar 
to photometric band like U,B,V) - will I extract 50/100 What ? KeV, 
Angstroms ? Hz ?  (for nu - frequency)

Is this to be said by queryData ? Well it may say the units=Anstrom but 
how to define range for special channel (again the analogy with filter - 
it may even have leakage and some opaque ranges (whis is explicitly 
rejected in this version of proposal by Pat)

I would prefer to recive from query to IRAS - we have 10, 25 mu zones or 
from X-ray we have bands .....hard,soft
which one would you like to get  ?

The client can easily build the interactive menu for choosing such 
selection options.
It is still resembling rather the Carlos's S3 protocol.


>
> Several people have expressed interest in image sections as in IRAF,
> CFITSIO, etc.  This is a pixel space expression such as "[101:105,*]"
> (spatial cutout of a 3-cube), "[*,5,*]" (plane 5 of a cube), etc.  In
> general, WCS-space and pixel-space operations are equally important and
> the client might prefer either.  AccessData is WCS-space initially as we
> already have to support this for the discovery query, whereas supporting
> pixel-space

I see the only application of pixel space for mosaics. Otherwise it might 
be used for reducing size of images to conserve space - like thumbnails of 
individual galaxies from SDSS ....
But it will be always very rough experimental size to select (well if I 
have CDELT1 I can compute pixel scale - but IMHO all reasonable science 
request will be driven in WCS space - in physical units ....

But I do not want to restart the discussion again....


thanks for support of BAND names