[tdwg-content] [tdwg-tag] DwC change review: geo terms

[Hilmar Lapp]

(Sorry if you receive this twice - John asked to repost here.)

Where is adopting these terms now going to put us with respect to OGC  
standards, which, I think, will ultimately be more authoritative than  
an informal W3C vocabulary.

I don't have enough insight into OGC standards for vocabularies for  
describing geolocations, but I have also learned earlier this year  
from Flip Dibner (copied here) that there are efforts underway within  
OGC to create RDF vocabularies (presumably corresponding to OGC's XML  
standards?).

	-hilmar

On Sep 6, 2011, at 6:33 PM, Javier de la Torre wrote:

> Hi John,
>
> As you mention from previous discussion I would still adopt option  
> number 1 as I believe there is enough tools out there to handle  
> transformations. The current situation I think is much worst on the  
> consumer part and I think is time to think more on data use than on  
> data mobilization.
>
> Best,
>
> Javier.
>
> On 07/09/2011, at 00:00, John Wieczorek <tuco at berkeley.edu> wrote:
>
>> Perhaps my message was too long for easy digestion and action, as  
>> I've
>> received no responses. I will take the initiative to initiate option
>> 3. No further action from the TAG on this at this point. Be prepared
>> though, VOTES by the TAG on publicly resolved issues are forthcoming
>> very soon.
>>
>> On Sat, Sep 3, 2011 at 9:34 AM, John Wieczorek <tuco at berkeley.edu>  
>> wrote:
>>> Hi TAGers,
>>>
>>> I am deep in the review process for the proposed changes to Darwin
>>> Core, trying to do due diligence. Some of the change requests are
>>> challenging to summarize to determine if there is consensus, in  
>>> spite
>>> of, or because of the discussions. One of the requests on which I’d
>>> like some TAG help before proposing a solution is the request for  
>>> the
>>> inclusion of the terms from the geo: namespace
>>> (xmlns:geo="http://www.w3.org/2003/01/geo/wgs84_pos#").
>>>
>>> Support in tdwg-content for this request comes from multiple
>>> independent sources. There has been a long history of discussion
>>> (http://lists.tdwg.org/pipermail/tdwg-tag/2010-August/000050.html),
>>> beginning in anticipation of the 2010 TDWG BioBlitz. The proposal  
>>> has
>>> gone through the minimum 30-day public review and discussion on the
>>> forum tdwg-content at lists.tdwg.org:
>>>
>>> http://lists.tdwg.org/pipermail/tdwg-content/2011-July/002581.html
>>>
>>> There seems to be general support for the additions, however, after
>>> reviewing the discussions and the references. I have the following
>>> observations/concerns:
>>>
>>> 1) The discussions presented geo:lat and geo:lng as W3C standards.
>>> This is not actually the case. These terms were created by the W3C
>>> Semantic Web Interest Group in 2003. The documentation for these  
>>> terms
>>> (http://www.w3.org/2003/01/geo/) states:
>>>
>>> "This document was created as an informal collaboration within W3C's
>>> Semantic Web Interest Group. This work is not currently on the W3C
>>> recommendation track for standardization, and has not been subject  
>>> to
>>> the associated review process, quality assurance, etc. If there is
>>> interest amongst the W3C membership in standards work on a
>>> location/mapping RDF vocabulary, this current work may inform any  
>>> more
>>> formal efforts to follow."
>>>
>>> These terms do seem to have widespread usage in the semantic web.
>>> Should we be concerned that they are not part of a standard?
>>>
>>> 2) geo:lat and geo:lng are not semantically equivalent to the  
>>> existing
>>> Darwin Core terms decimalLatitude and decimalLongitude, which have
>>> been a part of the Darwin Core since it 2003 (or before, if we  
>>> ignore
>>> the missing Datum term in earlier versions). The addition of the  
>>> geo:
>>> terms as a third set of geolocation terms for Darwin Core raised
>>> concerns about confusion. I share this concern. An option would be  
>>> to
>>> adopt these terms and deprecate dwc:decimalLatitude, dwc:Longitude,
>>> and dwc:geodeticDatum. Data that would have occupied these terms  
>>> would
>>> go instead to dwc:verbatimLatitude dwc:verbatimLongitude, and
>>> dwc:verbatimSRS. I see a couple of problems with this. First, most  
>>> of
>>> the time the data in the decimal coordinate fields are not the
>>> verbatim originals, so this would be a misuse of the Darwin Core
>>> terms. Second, this change would make it more difficult for data
>>> consumer’s to use existing georeferences. Here’s how. Right now the
>>> verbatim fields are meant to hold the original coordinate  
>>> information,
>>> which means they have a wide variety of content - everything from  
>>> UTMs
>>> to custom-encoded coordinates, in any conceivable format. Meanwhile,
>>> the data in the decimal coordinates fields can be much more readily
>>> transformed into the desired standardized spatial reference system
>>> afforded by the geo: terms, because the values are at least
>>> standardized on decimal degrees and only a datum transformation  
>>> has to
>>> be done on them.
>>>
>>> Do we abandon the dwc: terms decimalLatitude, decimalLongitude, and
>>> geodeticDatum? Do we abandon them now? Do we build the simplest
>>> possible tools necessary for anyone to do the transformations so  
>>> that
>>> these terms are no longer needed? If so, do we wait until those  
>>> tools
>>> exist?
>>>
>>> 3) Additional concern was expressed that the term geo:alt should  
>>> also
>>> be added. No one has made a formal request for this. However, if the
>>> other geo: terms were adopted, it might be silly not to adopt this  
>>> one
>>> as well. Doing so would raise a host of issues similar to those  
>>> raised
>>> for lat and lng.
>>>
>>> I don’t have a good solution. The best short-term one, in my  
>>> opinion,
>>> is to leave Darwin Core as it is, and to recommend that if
>>> applications (or aggregators) want to share “cleansed” point-based
>>> georeferences, that they do so with the geo: tags, the values for
>>> which they derive through transformations to WGS84 of the DwC  
>>> decimal
>>> coordinates and geodeticDatum.
>>>
>>> Options:
>>>
>>> 1) Accept the proposal, adding geo:lat, geo:lng, and geo:alt to the
>>> list of recommended terms for DwC.
>>>
>>> 2) Reject the proposal pending further directed research into a
>>> comprehensive solution that considers all geospatial terms in Darwin
>>> Core (including footprintWKT, for example).
>>>
>>> 3) Reject the proposal for now, reopening the public discussion with
>>> these concerns.
>>>
>>> Others?
>>>
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-- 
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: Hilmar Lapp  -:- Durham, NC -:- informatics.nescent.org :
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