utype for STC region in SIAP query response

[Francois Bonnarel]

Hi Markus, all,
Markus Demleitner a écrit :
> Hi Thomas, hi List,
>
> [utype for region withing SIAP]
>
> On Mon, Aug 29, 2011 at 02:44:06PM +0200, Thomas Boch wrote:
>   
>> I wish this is something that could be standardized in a forecoming
>> revision of the SIAP document, so that clients can easily find out
>> which FIELD support the STC-S description.
>>     
> Well, I'd say: the utype should reflect whatever place the region has 
> within the the "Simple Image" data model.  Since there's no such
> thing as far as I know, there should be no utype at all (though a UCD
> might come in handy)..
>   
This is not totally true actually and has been discussed during first 
discussions around SIA2.
The draft posted in Novembre 2009 (by the Garching IVOA meeting) has 
utypes proposals
for images (and cubes) which are actually nothing different from the 
Observation data model
as it was seen at that time... Apart from the mapping (wcs ) part and a 
few other details most
of it is also valid for generic datasets or observation descriptions...

In the mean time the Observation data Model Core components have been 
reworked within
the frame of ObsTap. There is an ObsCore utype for the kind of stuff 
Thomas is looking for, as I
Told allready...

What should be done now is to review the 2009 SIA draft and make the 
utypes totally
consistent with Obscore
> However, we do have an STC data model, and there's a Note [1] on how
> to embed the mapping of data in VOTables to it [disclaimer: mainly
> written by yours truly].  So, what I'd suggest is to just use that.
> If I may say so, it's much easier in implementation than one might
> think, and it'll remain the way it is even if we decide to define a
> Simple Image data model.
>
> In the note, there's already an example for embedding a region.  I
> think a future SIAP spec would profit from recommending a full STC
> record, and I'll be happy to figure one out -- just not right now
> since I'm on vacation.
>   
I think this is an option as long as you use the correct obs/sia2 utype 
on one of the
Fieldref/GROUPS... But as it is not that consistent with SIA/Obstap 
query response
structure (which don't say anything about defining GROUPS in the 
response VOTABLE) a field with
xtype : STC-S and utype "sia:Char.SpatialAxis.Coverage.Support.Area"

Best Regards
François
> Cheers,
>
>       Markus
>
> [1] http://www.ivoa.net/Documents/Notes/VOTableSTC/
>
>   


-- 
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François   Bonnarel           Observatoire Astronomique de Strasbourg
CDS (Centre de données        11, rue de l'Université
astronomiques de Strasbourg)  F--67000 Strasbourg (France)

Tel: +33-(0)3 68 85 24 11     WWW: http://cdsweb.u-strasbg.fr/people/fb.html
Fax: +33-(0)3 68 85 24 25     E-mail: francois.bonnarel at astro.unistra.fr
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