Frederic V. "Rick" Hessman wrote:
> On 1 Jun 2005, at 3:54 pm, Pierre Didelon wrote:
>
>> It was only my point of view (friendly i assume, at least when
>> writing it)
>> and certainly not "THE" UCD-SCI board pov, and I didn't want to hurt
>> you,
>
>
> No problem at all :-)
Ouf/Ah!
>
>> just express a (my?) difficulty when defining new UCD (similar to the
>> one we had
>> when trying to define UCD for planetology) which is related to the
>> definition of the "good level of abstraction" to be enoughly high to
>> be widely re-usable but at the same time enoughly precise to be
>> usable at all!
>
>
> This is why I probably sound somewhat exasperated: I keep feeling that
> something
> which sounds so simple, so necessary, and so obvious is meeting such
> resistance.
> I didn't join to partake in abstract philosophical discussions about
> ontological
> problems but to be able to teach my software how to handle events and
> observing
> requests. Thus, the whole goal has to be defining something which is
> exactly
> what you want: "good (enough) level of abstraction", "widely
> re-useable" and
> certainly "precise enough to be useful at all".
;-)
But something obvious or "natural" for somebody in a specific context
can have diff. meaning for somebody else in another context.
That's also why trying to convince colleagues of the usefullness of terms
is important, it force to express the implicit part of the definition.
See comment below on calib. The pb of galaxy.spiral is diff. I agree.
> On 1 Jun 2005, at 4:50 pm, Sebastien Derriere wrote:
[SNIP]
>> Currently, most of the existing UCD words are used to identify
>> the *properties* of the astronomical objects (detected sources).
>
>
> Exactly, except properties like "being a spiral galaxy" are not yet
> allowed
> even though properties like "being the rotation rate" are.
>
> Being a spiral galaxy in the VO universe shouldn't be tied to the string
> "spiral galaxy" but to an official VO concept, e.g.
> src.class.galaxy.spiral.
>
:-(
src.class.galaxy is perhaps ok (if I understand correctly the mail of Rob Seaman
http://www.ivoa.net/forum/ucd-sci/0506/0015.htm) then spiral can be an "additional"
property extracted from an enumerated list... official or project specific?
Not clear for me.
>
[snipp]
>
> This is getting away from "concepts" and toward "processes" and "models".
> Don't want to touch this can of worms! Suffice it to say that something
> like
>
> obs.image.calibrated
> obs.image.uncalibrated
Calibrated means astrometrically and/or phtometrically calibrated? Relative or absolute?
in which reference system? ...
What about spectral data, interferogramm, cosmic ray and neutrino detection?
All these data have diff. level of calibration, completly diff. one from the other.
Do we need to define all these in UCD, or something more general like
meta.dataset.status a property which can take values like raw, astrom.calib, photomCalib...
or whatever needed by a project or a context.
>
> would be handy, but connecting this to the correct
>
> obs.calib.flatfield
>
> isn't the job of UCD.
>
Agree ;-).
SY
PiR
Received on 2005-06-01Z18:44:10