Re: PROV-ISSUE-6 (define-location): Definition for Concept 'Location' [Provenance Terminology]

Dear Graham,

This phrase: "Typically a location is a physically fixed point" I copied from the OGC definition Carl provided.
I agree it is not a lucky formulation.

In ISO21127 we say: "Any object can serve as a frame of reference for E53 Place determination"

If we dig deeper in semantics, a location is an extent in space "geometrically fixed relative to a persistent material object" larger than the
extent. The notion of location makes only sense, if it preserves some meaning across time. In other words, if
I can find "the same place" again. This implies that the object of reference, for instance, the surface of earth,
is suffiently unaltered to say "I am at the same place", even though the local constellation of matter has changed.
I believe this is meant by OGC speaking about an "identifiable place".
Taking into account continental drift, there is actually no diachronically fixed point for the earth as a whole.
If I ask "what was here at the time of the dinosaurs" I refer to a piece of continental plate I stand on, not to
earth as a whole. The recent jumps of Indonesia and Honshu confirm the point.

The notion of location is useful either to verify what was there at the time of observation which lead to some data,
which we may take from other descriptions or going there at another time, or to verify material changes at that place
over time.

We may also be interested in relative movements of things outside the object on which we fix our reference system, for instance
the movement of Indonesia relative to Greenwhich. But I'd argue, that these are data for us, and not a notion of location in
the sense we need for Provenance, i.e., this is from "there". On other words, I expect no one to say "this is from there where
my house was before the earthquake" - which is several meters from its current position relative to Greenwich or so.

I'd add to your list:
  "geometrically fixed relative to a persistent material constellation " larger than the
extent.

Then we may even include astronomical intertial frames of reference fixed to a set of moving objects.

Best,

Martin



On 5/24/2011 11:29 PM, Graham Klyne wrote:
> Carl,
> Martin,
> and all,
>
> I think we're all broadly agreed in principle. So it comes down to what we actually have to say about location?
>
> Some particular topics I pick out of the discussion:
> - a location is an extent in space
> - location may be expressed with respect to any frame of reference, which may be terrestrial (or other planet based), or based (ultimately)
> on some arbitrary object
> - a frame of reference may occur at scales ranging from atomic to galactic and beyond
> - location may be expressed within its frame of reference by a metric scheme (coordinates, etc.) or by qualitative relation to
> characteristic features of the reference object.
>
> There's one thing in Martin's description I'd like to question: "Typically a location is a physically fixed point"; i.e. the reference to a
> "point". I suspect this was not meant to imply a location can be a point, though it is common to see an extent implied by some (unspecified)
> proximity to a given point (e.g. saying one's home lies at a given map reference). While this may be a common usage, I don't think it should
> form part of our definition of location. And if we do need to express point locations as well as extents, I think that needs careful handling.
>
> #g
> --
>
> Carl Reed wrote:
>> Martin -
>>
>> All you state is correct. Since then, the OGC definition work in the has gone much more "relative" :-) This because we now have folks
>> implementing OGC standards for brain scan applications, blood circulatory systems, the moon, Mars, inside buildings (local engineering
>> CRS) and so forth.
>>
>> However, please note that a CRS does not mean earth centric! A CRS can be an engineering coordinate system for a building design, local
>> such as in surveying, dynamic such as for moving satellite platforms, and so forth.
>>
>> There is a very interesting ISO standards that I have been involved in on ubiquitous location and spatial reference systems. The are
>> looking at a model that allows for easy transition say from the usual earth centric reference system (such as WGS 84-2d) into a shipboard
>> reference and so forth.
>>
>> Cheers
>>
>> Carl
>>
>> ----- Original Message ----- From: "martin" <martin@ics.forth.gr>
>> To: "Graham Klyne" <GK@ninebynine.org>
>> Cc: "Carl Reed" <creed@opengeospatial.org>; <public-prov-wg@w3.org>
>> Sent: Tuesday, May 24, 2011 11:18 AM
>> Subject: Re: PROV-ISSUE-6 (define-location): Definition for Concept 'Location' [Provenance Terminology]
>>
>>
>>> I agree with the points given by Graham, with minor exceptions.
>>> The ISO21127 elaboration is not a specialization of the OGC definition for
>>> a community, just the opposite. When we discussed in the CRM working Group adopting the OGC definition,
>>> we found it too narrow because it seems to be restricted to locations that can
>>> be expressed in coordinate reference systems and geographic-scale,
>>> but ISO21127 explicitly intended to comprise
>>> OPENGIS at that time, in particular for dealing with relative coordinate systems.
>>>
>>> We found that references to locations in terms of characteristic features of an object, such as
>>> "bow of a ship", "inner side of a wedding ring" "room G161" "front of a house" are not only culturally but also technically
>>> important. They are referred to in ontological literature as segments, sections, portions or parts.
>>> There are elaborate ontologies of such kind. In the proceedings of the ER Conference series,
>>> many of these are published.
>>>
>>> This is exactly example (2) by Graham below, and I strongly support it. .
>>>
>>> I'd suggest something like that:
>>>
>>> "A location is an identifiable extent in space, in particular on the surface of the earth, in the sense of physics.
>>> Typically a location is a physically fixed point, typically on the surface of the
>>> Earth, though locations can be relative to other, local or global non-earth centric coordinate reference systems
>>> or be relative to persistent features on material objects other than the earth. Non-earth centric coordinate reference systems may be
>>> fixed on persistent mobile material objects."
>>>
>>> cheers,
>>>
>>> martin
>>>
>>>
>>> On 5/24/2011 1:33 PM, Graham Klyne wrote:
>>>> I think the notion of location should be as generic as possible.
>>>>
>>>> To this end, I'd like to pose an additional example, which comes from a real scenario I've worked with, which suggests possible further
>>>> uses
>>>> of location provenance.
>>>>
>>>> I raise this because I think it's important that whatever definition we adopt for location does not rule out using the information
>>>> suggested
>>>> by this use case as part of a record of provenance information.
>>>>
>>>> ...
>>>>
>>>> Researcher H is investigating genomics in Drosophila (fruit flies), specifically genetic factors affecting spermatogenesis that may cause
>>>> sterility. To this end, she creates in situ hybridization (http://en.wikipedia.org/wiki/In_situ_hybridization) images of Drosophila testes.
>>>> Location information arises in a number of different ways:
>>>>
>>>> (1) starting from a microscopic image of testes treated to reveal gene expression, the researcher looks for occurrences of interesting and
>>>> clearly exposed gene expression patterns. These occurrences are recorded as a slide number and a coordinate location within the slide
>>>> image.
>>>>
>>>> (2) the spatial location of the gene expression within the testis structure gives a direct visual indication of the sperm development stage
>>>> at which a target gene is being expressed. This location is observed and recorded as a keyword from a controlled vocabulary that relates
>>>> the
>>>> gene expression to a developmental stage.
>>>>
>>>> As well as creating microscopic images, the tissue samples are subjected to a real-time PCR process
>>>> (http://en.wikipedia.org/wiki/Polymerase_chain_reaction) that gives a quantitative indication of the levels of a particular gene expression
>>>> product present in a sample. PCR is a batch process, where preparations based on different samples (targetting different genes, or
>>>> different
>>>> Drosophila species) are placed into different wells in a tray. This leads to:
>>>>
>>>> (3) The PCR analyzer presents by reference to the location of the various wells (identified by label or row/column position). The well
>>>> locations are in turn linked to details of the sample that has been placed in that well.
>>>>
>>>> Of these examples, I think that (1) and (3) are definitely part of the provenance information for a result. (2) is less clear, and I'd
>>>> judge
>>>> it to be part of the data rather than provenance information. But researcher H has also performed some follow-on research to analyzes
>>>> particular spatial patterns of gene expression, in which the location-based developmental stage might conceivably be considered to be
>>>> provenance information, in the sense of where the phenomenon was observed to occur.
>>>>
>>>> #g
>>>> --
>>>>
>>>>
>>>> Carl Reed wrote:
>>>>>
>>>>> Martin -
>>>>>
>>>>> A shorter version as defined in ISO 19112 and used by the OGC (since this was a jointly developed definition) is:
>>>>>
>>>>> Location: Identifiable geographic place [ISO 19112]. Typically a location is a physically fixed point, typically on the surface of the
>>>>> Earth, though locations can be relative to other, non-earth centric coordinate reference systems.
>>>>>
>>>>> I also noticed that the the European INSPIRE community working on cultural heritage sites are using CIDOC/21127 as well as additional OGC
>>>>> references, such as the URN syntax for spatial reference systems.
>>>>>
>>>>> Suffice to say, the definition for location in 21127 is a community elaboration of the more general OGC/ISO definition. We may need some
>>>>> such additional clarification for the provenance work - such as dealing with data provenance for articles, maps, charts, etc for the moon,
>>>>> Mars, and so forth.
>>>>>
>>>>> Regards
>>>>>
>>>>> Carl
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>>
>>> --------------------------------------------------------------
>>> Dr. Martin Doerr | Vox:+30(2810)391625 |
>>> Research Director | Fax:+30(2810)391638 |
>>> | Email: martin@ics.forth.gr |
>>> |
>>> Center for Cultural Informatics |
>>> Information Systems Laboratory |
>>> Institute of Computer Science |
>>> Foundation for Research and Technology - Hellas (FORTH) |
>>> |
>>> Vassilika Vouton,P.O.Box1385,GR71110 Heraklion,Crete,Greece |
>>> |
>>> Web-site: http://www.ics.forth.gr/isl |
>>> --------------------------------------------------------------
>>>
>>>
>>
>>
>
>


-- 

--------------------------------------------------------------
  Dr. Martin Doerr              |  Vox:+30(2810)391625        |
  Research Director             |  Fax:+30(2810)391638        |
                                |  Email: martin@ics.forth.gr |
                                                              |
                Center for Cultural Informatics               |
                Information Systems Laboratory                |
                 Institute of Computer Science                |
    Foundation for Research and Technology - Hellas (FORTH)   |
                                                              |
  Vassilika Vouton,P.O.Box1385,GR71110 Heraklion,Crete,Greece |
                                                              |
          Web-site: http://www.ics.forth.gr/isl               |
--------------------------------------------------------------

Received on Wednesday, 25 May 2011 11:20:30 UTC