SIAP details

[Doug Tody]

On Wed, 7 Jul 2004, Guy Rixon wrote:

> 1. How must the URLs for image query and image retreival be related to be
> valid?  Currently, I have http://my.server/path/to/siap/queryImage
> and http://my.server/path/to/siap/getImage, i.e. the two web methods are
> siblings; is this valid?

The acref URL (for the getImage) can be anything as long as it fetches
the image described in the query response.  It does not have to be
related to the base URL for the query method, although in implementation
terms it often is.
 
> 2. If the implementation does not support the INTERSECT parameter, what
> constraints are placed on how I determine the relevant data?  Can I just pick
> one of the values of INTERSECT and implement that?

Yes.  In general you err on the side of including candidate images and
let the client sort out the query response.
 
> 3. How do we deal with lacunarity?  My data has groups of four images with
> gaps between them.  Is it OK to check for intersection of the ROI and the
> overall footprint and disregard the cases where the ROI falls into one of the
> gaps?

It is ok, but if there is actually no data in the ROI then probably you
should omit the image.

Consider implementing a cutout service if your images are large.
 
> 4. Is there an official version of the SIAP standard on the IVOA site?  I've
> only found
> 
> http://us-vo.org/pubs/files/ACF8DE.pdf

Yes, SIAP is on the IVOA site under "documents".  The URL is

    http://www.ivoa.net/Documents/WD/SIA/SIA.html

Doug