Fwd: IVOA Trieste: Possible VOTable-JSON discussion?

[Marco Molinaro]

Hello Jean-Christophe,
I forward your contribution to the lists, while waiting how to
start/setup this splinter/meeting.

Personally I think that your suggestion in probably  a step further
than what's actually thought, but it's definitely worth keeping in
mind.

Cheers,
     Marco


---------- Forwarded message ----------
From: Malapert Jean-Christophe <Jean-Christophe.Malapert at cnes.fr>
Date: 2016-10-18 12:48 GMT+02:00
Subject: RE:IVOA Trieste: Possible VOTable-JSON discussion?
To: Marco Molinaro <molinaro at oats.inaf.it>


Hello Marco,

I think it should be useful to convert to GeoJson rather than json.
In addition, I have already a first implementation (must be improved)
: https://github.com/malapert/JsVotable, here exactly :
https://github.com/malapert/JsVotable/blob/master/app/converter/geojson.js
The only one problem is to define correctly the coordinate reference system.

The keyword (CRS) for the coordinate system was defined here initially :
http://geojson.org/geojson-spec.html

but this keyword was removed in the RFC7946
(https://tools.ietf.org/html/rfc7946) because of some problems between
OGC (Equivalent to IVOA for Earth) and the writer of the GeoJson
format. Actually in GeoJSON format, a position is defined by
[longitude, latitude] whereas in OGC is [latitude, longitude].

If we talk about coordinate system, we need to talk about STC because
it defines correctly a coordinate system. However, I do not think to
have XML in GeoJSON to define a coordinate system is good. A better
solution should be to reused WKT2 standard :
http://docs.opengeospatial.org/is/12-063r5/12-063r5.html. The WKT is
used here in spatialreference.org. Software uses spatialreference.org
to get the definition of a CRS in order to make projections (ex:gdal).
In addition, I know OGC has some discussions about WKT2 to describe
coordinate systems for planets.

Unfortunately, I will not be to IVOA to discuss about this topic.

Regards,
Jean-Christophe Malapert


________________________________________
De : dal-bounces at ivoa.net [dal-bounces at ivoa.net] de la part de Marco
Molinaro [molinaro at oats.inaf.it]
Envoyé : mardi 18 octobre 2016 00:49
À : François Bonnarel
Cc : apps at ivoa.net; <dal at ivoa.net>
Objet : Re: IVOA Trieste: Possible VOTable-JSON discussion?

Hi Stelios,
I agree with François, moreover I think that Apps should be contacted,
even if I'm not sure about program clashes.
Cheers
    Marco

Il 17 ott 2016 23:15, "BONNAREL Francois (OBS)"
<francois.bonnarel at astro.unistra.fr<mailto:francois.bonnarel at astro.unistra.fr>>
ha scritto:
>
>
> Dear Stelios,
>
>     This is exactly the kind of things we had in mind with the "DAL"  future discussion. Not sur it will be in DAL1 or DAL3 yet. We can add a lunch together if necessary, but i think it worth wheile to be discussed in full session.
>
>
> Regards to all
>
> François
>
> Le Lundi 17 Octobre 2016 22:12 CEST, Stelios Voutsinas <stv at roe.ac.uk<mailto:stv at roe.ac.uk>> a écrit:
>
> > Hello DAL,
> >
> > Following from some offline discussions we had during the IVOA Interop in South Africa, as well as discussions on the mailing list regarding a JSON VOTable output, I've compiled some notes into a wiki page which can be found here: http://wiki.ivoa.net/twiki/bin/view/IVOA/VOTable-JSONdiscussion
> >
> > Would there be interest in organizing an unofficial discussion for anyone interested in this during the Interop in Trieste? If there is enough interest, perhaps we could schedule something after the main sessions.
> >
> > Cheers,
> >
> > Stelios Voutsinas
> > WFAU, University of Edinburgh
>
>
>