Char DM and Sim DM: a use case

[Francois Bonnarel]

Dear all,

    As I was looking to the SIM data model, I was asked about the characterisation
of some specific derived  data coming out of the Horizon simulation. I am
speaking of these "maps" (either cubes or images) where the observable is a
physical quantity (density, temperature, metalicity, etc ....). These data look 
much closer to observational images and cubes than let's say ... snapshots of
particules. But indeed the physical quantity playing the role of Observable is
definetly a "property" in the sense of SIM DM, as far as I understand. 
 
     Presently the characterization class of Sim DM related to individual
properties and gathering some figures such as nominal value, min, max,
mean value, stdv is actually not inferred from the IVOA char DM. The
statistical moments needed by Sim DM are not currently present in Char
DM. But I am wondering if in the long term it could not be a problem for
IVOA to have this kind of discrepancy between two classes sharing the
same name and playing very similar roles. The use case I adressed above:
"Metallicity-kind maps" typically belongs to the two worlds. 

As we, in the "Observation subgroup" of the DM WG are trying to upgrade 
Characterisation data model in the direction of a fine grain description
with correct definitions and as SimDM is not yet recommended I am wondering
if it would not be possible to work on an harmonization .... What do you think ?

Cheers
François

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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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