SIAP postprocessing

[Douglas Tody]

Hi Petr -

Offhand I don't know how many of the existing SIA services have a cutout
or reprojection capability; there are a number, although most SIA
services are of the "archival" type, returning whole images as stored in
the archive.

The main use case we had for this is for distributed image analysis, so
that a client analysis program can get only the spatial region of
interest and not have to download the entire image.  This is especially
important for scaling up, either to get cutouts from many regions, or to
access portions of very large images.  The extreme case of this is
access to large data cubes, which SIAV2 is addressing.

> And what about the connection between image and catalogue - e.g. lists of 
> object available on image and restriction of catalogue rows when image is 
> cutout on-the fly..

Well you just limit the catalog query to the spatial region covered by
the image or cutout.  Some applications will do this for you automatically
but at the query level it is quite simple.  One thing we don't have yet
is support for multi-position queries, which would allow queries for
the many-region (e.g., cutout) use case.

> BTW I see the another usage for DataLink here - Image and associeted 
> catalogue - e.g. list of objects displayed - something like sextractor log 
> converted to magnitudes etc ....

Sure; obstap has the capability as well as it can associate images and
catalogs derived from the same observation.

 	- Doug



On Wed, 26 Sep 2012, Petr Skoda wrote:

> Hi all
> another question I have concerning involvement of my students in VO.
>
> There is a buch of SIAP servers and plans for SIAP2.
> As I was not until now interested in images and catalogues I do not have 
> personal experience with their operations and interoperability with Aladin 
> etc.
>
> So a naive question - how many of SIAP services has implemented the 
> postprocessing - i.e. makin cutout of requested field (in rectangle or 
> circle) and rebinnig, rotation, rescaling and format conversion - e.g from 
> FITS to jph, gif .....
>
> And how it is intended to use this in clients ?
> Namely Aladin
>
> And what about the connection between image and catalogue - e.g. lists of 
> object available on image and restriction of catalogue rows when image is 
> cutout on-the fly..
>
> BTW I see the another usage for DataLink here - Image and associeted 
> catalogue - e.g. list of objects displayed - something like sextractor log 
> converted to magnitudes etc ....
>
> Clever robotic telscopes have already the astrometry in WCS of raw frames so 
> most of the work could be automatized.
>
> Best regards,
>
> Petr
>
>
>
> *************************************************************************
> *  Petr Skoda                         Phone : +420-323-649201, ext. 361 *
> *  Stellar Department                         +420-323-620361           *
> *  Astronomical Institute AS CR       Fax   : +420-323-620250           *
> *  251 65 Ondrejov                    e-mail: skoda at sunstel.asu.cas.cz  *
> *  Czech Republic                                                       *
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