new characterization schema: STC Concerns and Proposal
Francois Bonnarel
bonnarel at alinda.u-strasbg.fr
Wed Sep 27 16:03:25 PDT 2006
The content of this (partial) answer has been discussed with Mireille
Igor and Anita, although the words are totally mine.
There are other things which we have been working on, not included
here but maybe later.
Here we describe why ObsDataLocation which we are reluctant to use
because it doesn't contain characterization semantics and even content
is not necessary in our context.
>I promised an example. I didn't do Anita's (though, if anyone
>insists, I can do it), but here is an optical image description that I
>fixed up (ignore the stylesheet info, the silly brightness units, and
>the many missing UCDs):
> http://hea-www.harvard.edu/~arots/nvometa/v1.30/M81image.xml
> - Arnold
>Arnold Rots wrote:
> When I asked yesterday why Characterisation wasn't using higher-level
> structures from STC, I was actually serious and even more so after
> Anita's presentation and some of the concerns that Igor voiced.
> I realized that the Characterisation schema is going through the same
> issues now, that I went through in the development of the STC schema,
> in terms of required axes, elements, and references. It seems
> unnecessary to have to rehash all of that again.
> In particular, by rebuilding the STC-related elements from lower level
> STC components the integrity of the coordinate metadata in the related
> axes is lost and it will be a major effort to regain it.
What the characterization axis first xml schema uses for coverage
is AstroCoordSys, AstroCoords and AstroCoordArea, either directly or as
derivation. We will have one instance per Axis.
AstroCoords and AstroCoordArea have a pointer to a coordsystem as
an attribute (coord-system_id). So I think these are correctly defined
STC structures.
> The thing is that all of the axis-related stuff in Characterisation is
> contained in the ObsDataLocation element in STC, with the exception of
> sensitivity.
ObsDataLocation is the gathering of one ObservatoryLocation ,one
ObservationLocation and one PixelLocation
1 We actually do not need the PixelLocation in Characterization , because
we always consider the data at some level of calibration only.
2 ObservatoryLocation will be generally borrowed from the library
3 So the only part to be considered is "ObservationLocation"
ObservationLocation gathers (several) AstroCoordSys, (several) AstroCoords
and (several) AstroCoordArea. Lack of any of them is also allowed.
It doesn't appear to me where this solution provides any additional
linkage between all these structures compared to the referencing provided
by the coord-system_id attribute in AstroCoords and AstroCoordArea
which are exactly the structures we use in Characterisation (see above)
So, for me it doesn't add anything to the rigor of the xml
serialization to use such a high level ObsDataLocation in the schema.
>It would be a rather simple thing to add the sensitivity
> concept to stc:AstroCoordArea.
>When that is done you would have a
> complete implementation of the axis-related characterisation in
> stc:ObsDataLocation,
>complete with all the proper structure and added
> value in a fully implemented referencing mechanism.
> It is easy to see that Anita's example would be completely represented
> in this - I'll provide an example of it next week.
>
> I am not proposing any change in the Characterisation _model_, only in
> the XML schema implementation by simply plugging in ObsDataLocation
> which is a ready, complete, and tested element.
> Note that this same ObsDataLocation element is also used in the
> VOEvent schema.
>
> I know that the organization of the information is different - the
> matrix is transposed, so to speak. But that was done to facilitate an
> easier implementation of the related coordinates. And it is only a
> matter of code: it should not be harder to present the information in
> a transposed view.
>
> And I don't think it would delay the process, either. As I said, the
> model (and hence the WD) is not affected, while the schema development
> will be easier since all coordinate concerns are taken care of. I
> promise to add the sensitivity components right away to STC since it
> does not seem like that will be difficult since I should be able to
> take it from the current Characterisation schema.
>
> Cheers,
>
> - Arnold
>
> Francois Bonnarel wrote:
> [ Charset ISO-8859-1 unsupported, converting... ]
> >
> > Hi all,
> > Version 0.95 of the characterization xml schema (axis first) is available
> > following this link :
> > http://Model/Characterisation/schema/characterisation.0.95.xsd
> > It has been properly validated, importing stc1.3 schema and using
> > xmlspy. So it could be possible to use it to develop validated examples.
> >
> > Best regards
> > Fran?ois
> >
> > =====================================================================
> > Francois Bonnarel Observatoire Astronomique de Strasbourg
> > CDS (Centre de donnees 11, rue de l'Universite
> > astronomiques de Strasbourg) F--67000 Strasbourg (France)
> >
> > Tel: +33-(0)3 90 24 24 11 WWW: http://cdsweb.u-strasbg.fr/people/fb.html
> > Fax: +33-(0)3 90 24 24 25 E-mail: bonnarel at astro.u-strasbg.fr
> > ---------------------------------------------------------------------
> >
> --------------------------------------------------------------------------
> Arnold H. Rots Chandra X-ray Science Center
> Smithsonian Astrophysical Observatory tel: +1 617 496 7701
> 60 Garden Street, MS 67 fax: +1 617 495 7356
> Cambridge, MA 02138 arots at head.cfa.harvard.edu
> USA http://hea-www.harvard.edu/~arots/
> --------------------------------------------------------------------------
>
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Arnold H. Rots Chandra X-ray Science Center
Smithsonian Astrophysical Observatory tel: +1 617 496 7701
60 Garden Street, MS 67 fax: +1 617 495 7356
Cambridge, MA 02138 arots at head.cfa.harvard.edu
USA http://hea-www.harvard.edu/~arots/
--------------------------------------------------------------------------
=====================================================================
Francois Bonnarel Observatoire Astronomique de Strasbourg
CDS (Centre de donnees 11, rue de l'Universite
astronomiques de Strasbourg) F--67000 Strasbourg (France)
Tel: +33-(0)3 90 24 24 11 WWW: http://cdsweb.u-strasbg.fr/people/fb.html
Fax: +33-(0)3 90 24 24 25 E-mail: bonnarel at astro.u-strasbg.fr
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