(r27) CharacterisationDataModel < IVOA

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<H1> DM work package : Characterisation Data Model</H1>
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 %RED% !!!New page(Feb 2010)!!! %ENDCOLOR% %GREEN%Work in progress : Site under re construction %ENDCOLOR%                

   * coordination :  [[IVOA.FrancoisBonnarel][François Bonnarel]] 
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<H2>Goal </H2>
   This workpackage is aiming at defining the high level metadata necessary to describe the
astronomical data sets on their physical axes, either observed or simulated,
for various types of data like 2D-images, data cubes, X-ray event lists, IFU
data, etc.. 
   The goal is to provide an abstraction which contains structured
information for all these types of data so that discovery and interpretation
is feasible in a general framework, and can be used jointly for science cases.
The model aims at facilitating the manipulation of heterogeneous data in VO
portals. A VO Characterization instance can include descriptions of the data
axes, the range of coordinates covered by the data, and information on the
data sampling and resolution on each axis. These descriptions are in terms of
physical variables, with the specific instrumental signature abstracted away.
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<H2>Characterisation 1 Legacy</H2>

    * Characterisation Data Model effort led to a publication of a version 1 of the Data Model in 2008 [[CharacLegacyPage][(see legacy page)]]

<H2>Towards Characterisation version 2</H2>

    From September 2007 on, a new effort started to take into account both dissemination of the model in Data centers and completion of the model for some complex use cases.

<H3>List of participants</H3>
Mireille.Louys, Alberto.Micol, Igor.Chilingarian, Peter.Skoda, Fabien.Chereau, Carlos.Rodrigo, Miguel.Cervino, Juan De Santander, François Bonnarel, Anita Richards, J.Mc Dowell, Gerard Lemson.
After October 2008 Interop meeting work mainly involved I.Chilingarian , M. Louys and F.Bonnarel

<H3>Sorting out the issues</H3>

   In April May 2008 we started to [[%ATTACHURL%/AfterTrieste.pdf][discuss the issues]] and Fabien proposed a [[%ATTACHURL%/Chereau.pdf][new definition of the characterisation concept]].
 
<H3>Building Examples</H3>

    A couple of examples in XML were developed by extending Characterisation schema 1.11 to fullfill following use cases:

    * Polarization images : with 3 flux axes ([[%ATTACHURL%/polarization.xml][xml]],[[%ATTACHURL%/Grid-polarization.xml.png][Grid view]])    

    * Polarization images : with one complex flux axis

    * Complex characterisation (CCD mosaic case)

Discussion on these examples can be read there.

<H3>Model Simplification</H3>   

     The discussion also enhanced the difficulties to implement the data models in services and archives due to ill-definition of some concepts, complexity of xml definition or lack of protocols to transport model-consistent metadata. Summary of the discussion can be found here. Fabien Chereau presented his own views at the baltimore Interop, and some [[%ATTACHURL%/CharacInJSON.txt][JSON serialisation of the characterisation datamodel]] has been proposed by T.Boch. 

    
 

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Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who	Comment
pdf	AfterTrieste.pdf	r1	manage	51.0 K	2010-02-19 - 18:38	FrancoisBonnarel	Characterisation Issues Spring 2008
txt	CharacInJSON.txt	r1	manage	2.4 K	2010-03-12 - 17:52	FrancoisBonnarel	example of characterisation in JSON format
pdf	Chereau.pdf	r1	manage	193.2 K	2010-02-22 - 11:04	FrancoisBonnarel	Staistical Characterisation definition
png	Grid-polarization.xml.png	r1	manage	105.4 K	2010-02-22 - 15:06	FrancoisBonnarel	polarization char grid
pdf	NewChar2.pdf	r1	manage	569.3 K	2011-07-31 - 11:35	FrancoisBonnarel	Characterisation 2 data model Draft
xml	polarization.xml	r1	manage	9.4 K	2010-02-22 - 13:25	FrancoisBonnarel	Polarized image data characterization example 1
xml	polarizationbis.xml	r1	manage	7.2 K	2010-02-22 - 13:26	FrancoisBonnarel	Polarized image data characterisation example 2

Topic revision: r27 - 2011-07-31 - FrancoisBonnarel

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