DataModel23012003 < IVOA

IVOA Web>IvoaDataModel>DataModel23012003 (2003-01-29, MarkusDolensky) (raw view)
---++ Data Modeling Meeting 

ESO, Garching, Jan. 23/24, 2003

|*Initials* |*Participant* |*Affiliation* |
|PB |Pascal Ballester|ESO |
|FB |Fran&ccedil;ois Bonnarel|CDS |
|PD |Pierre Didelon|Terapix |
|MD |Markus Dolensky, chair|ESO |
|JH |Jonas Haase|ST-ECF |
|ML |Marco Leoni|ESO |
|MIL|Mireille Louys|CDS |
|JMD|Jonathan <nop>McDowell</nop>|<nop>CfA</nop> |
|AM |Alberto Micol, minutes|ESA |
|BP |Beno&#238;t Pirenne|ESO |
|BV |Bruno Voisin|Astrovirtel visitor |


---+++ Agenda

 Day 1, Room 231, 1:30 pm - 5:15 pm

|   *#*   |   *Time*   |   *Moderator*   |*Topic* |
|  1| 13:30|   MD   |Intro, report on IVOA working groups |
|  2| 14:00|   JMD   |IVOA data models |
|   | 15:00| |break |
|  3| 15:20|   MIL   |start open discussion of ... |
|   | | |- reduction pipelines |
|   | | |- data quality |
|   | | |- hierarchy/granularity |
|   | | |- versioning |

 Day 2, Room 232, 9 am - 12 am

|   *#*   |   *Time*   |   *Moderator*   |*Topic* |
|  4|  9:00|   FB   |Aladin GOODS tree and IDHA data model |
|  5|  9:50|   JMD   |Chandra pipeline architecture |
|  6| 10:30|   AM   |HST pipeline architecture |
|   | 11:10| |break |
|  7| 11:25|   MD   |Formation of IVOA Data Modeling Standardization Group |
|   | |   MD   |Events 2003 |

Meeting split for informal discussions within ESO.


---++ Notes About Individual Agenda Items

   *1 [MD]: [[%ATTACHURL%/ivoa_wg.txt][IVOA meeting conclusions]]*

-----------------------------------------------------------------

   *2 [JMD]: VO Data Models: status*

[[%ATTACHURL%/dmtmin.txt][report on boston meeting]], Oct 2002

See above minutes for meaning of conforming data model and modelling exercise on spectral bandpass.

Wavelength/Frequency model
<verbatim>
  <ENERGY>
   <MODE>Wavelength</MODE>
   <VALUE>512.02</VALUE>
   <UNIT>nm</UNIT>
  </ENERGY>
</verbatim>

or

<verbatim>
  <WAVELENGTH UNIT="nm">512.02</WAVELENGTH>
  (#PC: <FRAVERGY TYPE="wavelength" UNIT="nm">512.02</WAVELENGTH>?)
</verbatim>

What is an image?
   * sparse (with bad pixel map) is ok
   * must have regular pixellated array
   * must have pixels with scalar simple data types (int, real, complex, char?)
   * can have n dimensions, n arbitrary

Aggregation is generally better/simpler than inheritance (HAS-A instead of IS-A)

What is data, hypermaps, images, tables, documents, code, plots, links, etc?

[[http://hea-www.harvard.edu/~jcm/vo/dmtm][related documents]]

-------------------------------------------------------------------

   *3 [MIL]: open discussion on ...*

   * reduction pipelines
   * data quality
   * hierarchy/granularity in metadata
   * versioning

IDHA (Images Distribu&eacute;es H&eacute;t&eacute;rog&egrave;nes pour l'Astronomie) team:
   * CDS FB, A.Oberto, et al
   * LSIIT ML, C.Collet
   * IAP, PD, Y.Mellier, E.Bertin
   * QUB: F.Murtagh

images in astronomy
   * A. metadata definition for image sets in diverse arch.
   * B. multicolor image analysis for obj. recognition and cross identification

Goal: provide a mode for astronomical image data
http://alinda.u-strasbg.fr/IDHA/datamodel.html

a) reduction pipeline
   * [JMD] 'region object' to describe FOV 
   * make more general object which has a common concept for raw and processed images

b) data quality

   * measure for quality: dm richness (detailed), traceability (raw<=>publi.)

c) granularity

   * [BV] How about applicability XSLTs to manipulate XML DMs?
   * raw - cal. - mosaic - rgb ...

d) versioning

   * feedback loop: obs. - reduc. - visual. - interpret. (and back to obs.)
   * software versioning/data versioning

      
---------------------------------------------------------------------
Day 2
---------------------------------------------------------------------

   *4 [FB]: How data model + votable was used in AVO GOODS demo*

Bonnarel, Louys, Boch, Fernique, Schaaf, Derriere, Ochsenbein

from datamodel to xml
   * visions of data model must be translated in documents for describing
  metadata (different scenarii for different users/applications)
   * xml good for exchanging
   * votable or some other dtd ? -> votable because already accepted
   * how to code a Tree (partial view of a DM) into a table oriented DTD?
   * chance: definition of VOTable RESOURCE is recursive (1->n links)
   * each class of the model is defined as a RESOURCE (fixed name, no ID in order to allow multi-occurance), with a specific table part
   * children classes as nested resources 
   * [JMD]: How to link a filter in the Observing_group table to the filter given in the filter resource? 
   * GOODS image server has more functionalities than public aladin; public aladin will inherit those, but not before summer
   * SIAP is flat, no hierarchy, output = single table
 
-----------------------------------------------------------------

   *5 [JMD]: Chandra pipeline*

 chandra -> telemetry -> fits files with mnemonics (Level 0)

 Level 1: takes level 0 data -> calibrated scientific file

     Events
     ASOL (Aspecs solution, geometry vs time ra,dec,roll(t)),
          spacecraft attitude, bending of telescope tube, 
           (1 arcsec within an observation!)
     HK, temperature, radiation environment, etc
     -> ra, dec for all photons, 

 between level 1 and 2:
    observation can be split up -> level two combines them

    typical exptime: 50ksec to 100ksec (some 1ksec, some 1Msec)

    level 2 removes garbage: L2 data is just a starting point
                             used by naive users, experts will go back to L1

      L1->L2 pipeline is publicly available 

  L3 pipeline (not yet in place): to generate uniform source catalogs, etc

L2 event list (EVT) -> binned on the fly to provide an image
                       of requested resolution/size

dmcopy evt2.fits[energy=2000,5500][time=from,to][bin x=3000:4000:4,y=...]
produces the requested image.

IDHA covers some part of Chandra calibration system, but not the bookkeeping.

-----------------------------------------------------------------

   *6 [AM]: HST pipeline*
   
in contrast to Chandra ...<br>
   * pixel info and header info come from different sources (files + DBs) when assembling raw files
   * science and engineering streams are separated for HST, but not for Chandra

[PB] reports that IAU interferometry WG exists to define data format for interferometry

-----------------------------------------------------------------

   *7 [MD]: Forming IVOA Data Modeling Standardisation WG*

   * Forum: dm@ivoa.net
   * Lead:    Jonathan <nop>McDowell</nop> (<nop>CfA</nop>)
   * Members 
      * Alberto Micol,
      * Mireille Louys,
      * ?Dave Giarretta?,
      * others...        

-----------------------------------------------------------------

For events 2003 see Avo:AvoEvents

further ...
   * NVO meeting in Nashville with AAS in June
   * NVO team meeting, where?, March, 

-----------------------------------------------------------------

Meeting adjourned. Splinter discussions followed on:
   * a possible model for a distributed Aladin, to access both data and metadata directly from the VO data centres, without the need of storing them in the Aladin server.
   * UCD discussion
   * a possible design for a Data Model suitable for an ASTROVIRTEL Exposure-Time-Calculator-based archive search engine. Version 0.2 will be drafted and sent to participants.


-----------------------------------------------------------------

   *Action Items*

   * [JMD] announce creation of DM group to ivoa@ivoa.net
   * [MD] register below members with dm@ivoa.net: Haase, Micol, Leoni, Didelon, Bonnarel, <nop>McDowell</nop>, Louys, Dolensky, Voisin



<small>(minutes written by A. Micol; edited by M. Dolensky)</small>

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I	Attachment	History	Action	Size	Date	Who	Comment
txt	ivoa_wg.txt	r1	manage	1.1 K	2003-01-29 - 14:00	MarkusDolensky	initiating IVOA standardization working groups
Topic revision: r2 - 2003-01-29 - MarkusDolensky
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