(r1) DataModel23012003 < IVOA

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---++ Data Modeling Meeting 

ESO, Garching, Jan. 23/24, 2003

|*Initials* |*Participant* |
|PB |Pascal Ballester|
|FB |Francois Bonnarel|
|PD |Pierre Didelon|
|MD |Markus Dolensky, chair|
|JH |Jonas Haase|
|ML |Marco Leoni|
|MIL|Mireille Louys|
|JMD|Jonathan McDowell|
|AM |Alberto Micol, minutes|
|BP |Benoit Pirenne|
|BV |Bruno Voisin|


---+++ Agenda

 Day 1, Room 231, 1:30 pm - open ended (~5 pm)

|   *#*   |   *Time*   |   *Moderator*   |*Topic* |
|  1| 13:30|   MD   |Intro, report on IVOA working groups |
|  2|  9:45|   PF   |status of Aladin |
|  3| 11:00| |coffee break |

 M Dolensky: report on IVOA meeting conclusions
 J McDowell: status of data modeling efforts
 M Louys:    start an open discussion of
              - reduction pipelines
              - data quality
              - hierarchy/granularity in the metadata
              - versioning

 AOB

 Day 2: room 232, 9am - max 12pm

- F. Bonnarel: how data model + VOTable was used in AVO GOODS
               first light demo

AOB (P.Didelon ?)

-M.Dolensky:   events 2003, plans
               wrap up


---++ Notes About Individual Agenda Items

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


JMD: VO Data Models: status

     boston meeting goals were: 
          compare existing models
          ...
          ...
     compliant data model:
       first: to write the concept one wants to describe
       second: UML or equivalent based model
       third: convert UML to XMI or equiv. and verify model schema
              satisfies VO DM standards (see below)
       fourth(optional): provide a reference XSD schema and
                         XML instance examples.
                         IVOA InterOp. group can adopt model as
                         a recommended VO model for the given concept.

     Conforming IVOA Data Models
     unique URI
     unique name
     version
     description
     curation metadata
     url for white paper
     class descriptions: 
        - name and description
        - attributes, name,type,quantity,cardinality,defaults, units?
        - properties
        - methods

bandpass methods and attributes
 effective lambda
 min and max lambda/freq/energy/wave numbers
 transmission curve (add or multiply?)
 theoretical transmission curves (also as function of time, temperature)

 uncertainties on each number!
 quality object (non numerical description)
 
 problems: red leaks, periodic filters,
           wedge and band stop (notch) filters
           multiple filters
           atmospheric transmission ?

  bandpass attributes
   - name, generic name, waveband name
   - central and end wavelengths
   - measured ot theoretical transmission function
    what about zeropoints ?

  bandpass classes  NOT DISCUSSED

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

  or

  <WAVELENGTH UNIT="nm">512.02</WAVELENGTH>

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

  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 better 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

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

ML: open discussion
    - reduction pipelines
    - data quality
    - hierarchy/granularity in metadata
    - versioning

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

Granularity: BV? better having XSLTs onto your XML DM ?
             
---------------------------------------------------------------------
Day 2
---------------------------------------------------------------------

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
 

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.


AM: HST pipeline
    ...

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


MD: IVOA Data Modeling Standardisation WG

Forum: dm@ivoa.net

Lead:    Jonathan McDowell (CfA)
Members: Alberto Micol (ST-ECF),
         Mireille Louys (CDS),
         ?Dave Giarretta (ASTROGRID)?,
         ? someone else ?        

Remarks (scope, goal, ...)

for events 2003 see Avo:AvoEvents

us-vo Nashville, June aas meeting (but sidney ...)
NVO team meeting, ?, March, status reports

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.




<small>(created by IVOA.MarkusDolensky %GMTIME{"$day.$mo.$year@$hours:$minutes:$seconds"}%)</small>
<br><br><br>

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Topic attachments
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: r1 - 2003-01-29 - MarkusDolensky
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