VEP-006: Discussion summary

[Mireille LOUYS]

Hi every one ,

Sorry for this late answer .

As shown in the latest paragraph , as it has been discussed in examples 
on the list , and at interop splinter meeting recently,
it seems we should have a split between two notions and do not live for 
an intermediate fuzzy annotation , that would be difficult to change 
afterwards.

Confusion today for some datalink services would mean confusion 
tomorrow, when we reuse existing examples to build new services .

So better clarify *now* the split between progenitor and calibration.

this is the datalink's  semantics labels tree I would go for :

#data
     #progenitor  data used to create #this

     #auxiliary data use to facilitate the interpretation of #this: for 
understanding data quality or reprocessing , etc .
         #calibration-applied
         #calibration-applicable

and it would solve the pb of mixing  #progenitor and #calibration 
labels, which is a situation we want to avoid.

Best , Mireille

Le 08/06/2021 à 10:05, Markus Demleitner a écrit :
> Dear Semantics community,
>
> At the interop, we had a side meeting on VEP-006 (#calibration
> definition).  I *think* we reached a sufficient consensus here, as
> usual with some reservations.  I have tried to summarise the
> discussion in VEP-006,
> https://volute.g-vo.org/svn/trunk/projects/semantics/veps/VEP-006.txt
>
> I'm also reproducing it below.  Do people feel their contributions
> sufficiently considered and represented?  If not, what changes would
> you like to see (direct commits to Volute cordially invited)?
>
> Thanks,
>
>               Markus
>
> And here's VEP-006 as of rev. 5976:
>
> Vocabulary: http://www.ivoa.net/rdf/datalink/core
> Author: Markus Demleitner <msdemlei at ari.uni-heidelberg.de>
> Date: 2020-09-09
>
> Term: #calibration
> Action: Modificiation
> Label: Applicable Calibration
> Description: Data products that can be used to remove instrumental
>    signatures from #this.  Note that the calibration steps such data
>    products feed have not been applied to #this yet.   To link
>    calibration data already reflected in #this, use #progenitor.
> Used-in: http://dc.g-vo.org/kapteyn/q/dl/dlmeta?ID=ivo%3A//org.gavo.dc/~%3Fkapteyn/data/fits/POT015_000317.fits
>
> Term: #bias
> Action: Modification
> Description: Data products that can be used to remove detector offset levels
>    from #this.
>
> Term: #dark
> Action: Modification
> Description: Data products that can be used to remove detector dark
>    current from #this.
>
> Term: #flat
> Action: Modification
> Description: Data products that can be used to remove the signature of
>    non-homogeneous detector sensitivity from #this.
>
> Rationale:
>    In a discussion on the semantics mailing list (see
>    http://mail.ivoa.net/pipermail/semantics/2020-June/002735.html
>    and follow-ups) it was found that the existing descriptions of
>    #calibration and its narrower terms are ambiguous; "resource used
>    to calibrate" could mean both "resource that has been used" or
>    "resource that can be used".  This VEP tries to make it clear that the
>    "has been used" interpretation is for #progenitor, wheras #calibration
>    is for "can be used".
>
> Discussion:
>    On the Semantics mailing list
>    (http://mail.ivoa.net/pipermail/semantics/2021-March/002774.html and
>    followups), concerns were brought forward that excluding calibration
>    data already applied would unnecessarily complicate the vocabulary;
>    the temporal aspect ("has been applied" vs. "can be applied") should,
>    if possible, be kept out of it.  Against that it was put forward that
>    doing this would leave parts of #calibration within #progenitor (the
>    "has been applied" part), other parts essentially in what some people
>    suggested is #auxiliary (the "can be applied" part").  This violates
>    the conditions for keeping the concepts organised in a tree, which
>    was considered undesirable.
>
>    On the other hand, it was recognised that being able to trace "science
>    data" (as opposed to auxiliary resources like calibration data)
>    through the provenance chain is valuable.  A method proposed to effect
>    this, given that with VEP-006 #calibration is not available for this,
>    could be to narrow the definition of #progenitor to "less calibrated
>    science data".  But even if this step is not taken and #progenitor
>    remains "anything upstream in the provenance chain", a new term
>    #calibration-applied would seem useful (an example given was: when
>    fusing 50 images, people want to tell those apart from, for instance,
>    a master PSF that also went into the fusion).  Parties having use for
>    such a concept are encouraged to author a VEP for it.
>
>    In the end, after a side meeting at the May 2021 Interop consensus was
>    found that #calibration should certainly not contain elements both in
>    and outside of #progenitor; it was agreed that while, if we started
>    again today, we would call the VEP-006 #calibration something like
>    #calibration-applicable.  However, given the label is there, and that
>    the level of detail below #calibration (with #bias, #dark, and #flat)
>    probably mainly is useful (as far as datalink with its focus on
>    actionable semantics is concerned) when a client wants to
>    semi-automatically perform the calibration itself, it was decided that
>    #calibration is kept with its label changed to "Applicable
>    Calibration" and a corresponding definition.
>
>    As we sharpen the definition of #auxiliary ("resources aiding the
>    scientific exploitation of #this"), #calibration should probably
>    become a child of it.  This, however, would be part of a VEP on
>    #auxiliary.

-- 
--
Mireille Louys,  MCF (Associate Professor)
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